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Monday 08 May , Dr Thomas Kluyver, Soton Uni : The Southampton Sailing Robot Project
26 people , 1.5hr
I was asked to get involved with a robotic sailing project as I'd done a bit of
sailing and I liked fiddling with computers. 9 months after that I was on the
way to Satanstead airport , to fly to Portugal for the World Robotic
Sailing Championship , 2016, a whole lot of fun.
With me tonight are Tony and Sim who were also part of the team,
and a number of other people , 9 in total and 7 of us
went to Portugal. Of the 9 in our team , all were of different
The first thing you need is a boat. We initially thought we'd build a boat,
but that is difficult and time-consuming. There is a community who
do remote control sailing , including a class called the 1m class,
1m long . Plenty of these already made and we bought a secod-hand one,
for something like 200GBp. There are 3 sets of sails, for different
wind conditions, smallest for strongest wind and smallest for weak winds.
Nice thing about an r/c sailing boat , it already has the servo motors
to move sails and rudder , a chunk of the work already
done for us. So the bits are radio receiver with aerial , about an inch long.
2 servos, the one with the large round bit is the sail servo, pulling the sail
in to the boat centre , then a more standard servo that turns the rudder.
Then you need a computer to control the robots. So a Raspberry Pi,
a tiny computer 2x3 inches with processor , memory plus a removable
memory card for the programs. You can connect it up to a
network , no screen or keyboard but once its connected
to a network we can talk to it from standard computers, move the
programs onto it, get data off it, tell it what to do next.
A lot of exposed electronics, which don't mix with water
, especially salt water where the competion is held. So Tupperware
boxes to keep most of the water out of it. Wires through holes made in the
box to the servos and sensors, holes sealed with gummy stuff.
We roughly cut a large hole in the hull side , so we could
slot the computer inside . When sailing the joins to that panel
covered in tape , as waterproofing. And more tape over
other places where water could get in. The brain of the operation got
called Brian. The boat is called the Black Python , like the
Pirates of the Caribean , Black Pearl, but the computer language we use
For the sensors we made one from an off the shelf windvane, glued to
2 ring shaped magnets to it, coupled to a board that senses magnetic fields
so we can detect what orientation the magnets are in , and so which
direction the wind is blowing across the boat. Mounted on the
top of the mast about 2m obove the deck, to avoid the sensed wind being distorted by the
sails. Under the hull is a weighty blade like keel to counterbalance the
lean from wind pressure on the sails ,across the hull.
We need a GPS . Al lthe competion challenges require negotiating
around marker bouys that we are given
GPS co-ordinates, Lat and Long. The boat needs to know where it is
, to go to where it needs to go. This GPS is also on the mast,
about 2 inches long , this one otherwise used for high altitude
ballooning , apparently that type works well for this sort of app.
Cost is only something like 7 or 8 GBP.
A compass to show which way the boat is pointing, an accelerometer
to tell if the boat is leaning and you need that to adjust the compass,
a board about an inch square, MEMS micro-electro-mechanical sensors.
A way to get physical data into a form that can be electronically
processed. We have to calibrate the compass for each use, 2 people
holding the boat and turning it in a circle, the calibration dance.
Now how do we put the bits together and make it sail.
Why is this an interseting challenge, why difficult for a robot.
There are othe rchallenges where the boat has motors, there is a Soton
team called hydro-team , boats with motors. So the control to go
from A to B is pretty straightforward. Point it in hte right
direction and tell it to go.
For sailing , it is dependent on the wind direction , it can't go
straight into the wind, 90 degrees to the wind or have it behind
and modern boats can go 45 deg to the wind. A better boat will
let you go closer to the wind. You have to zig-zag to go into the
wind, tacking. 45 deg to the wind one way , go about 90 deg
across the wind and sail on the opposite tack .
Eventually you get where you need to go. This is where control
of the sail position comes in . Running in front of the wind,
you can let the sail out as far as it will go , near enough. It acts
as a big bag, like Viking long ships with a big square sail .
These boats go fastest at about 90 deg to the wind by
putting the sails at about 45 deg, then the sail is acting like an
aerofoil , like the wing of a plane. The wind is perturbed around the
curves and pushes the boat forwards efficiently.
If you want to sail close to the wind , you pull the sail closer in ,
it will keep you going forwards. This is partly the function of the keel .
If going across the wind , you don't want to drift in the direction of the
wind, sideways. The keel blade helps to keep you straight.
We did most of our tests at Eastleigh Lakes near the airport.
We also borrowed anothe rboat , to test out our control
systems before our competition boat was ready. That boat was
simpler with 1 sail, our main boat has 2, mainsail and jib.
Some boats the sails are controlled separately but our boat
, the 2 sails are controlled from 1 servo, they move together.
There is asome ability to adjust them separately
, for when we set-up the boat , we can adjust where the sheets are
connected . Once its on the water they go togehter.
We ended up with 2 borrowed r/c Lasers and we could test the
r/c on one and the control systems on the other.
A big pole has a wifi antenna on the top so it gets us
better range and stay in contact with the boat during
testing. Requiring keeping rain and sun off the control
laptop. The antenna is very directional , requiring it
being pointed to the boat , which can get a bit tedious.
During the competition , this kind of contact was intermittant
, we were trying to keep a wifi connection from the bank
but the challenge area was several 100m away from us
and a dodgey connection. But the boat does not actually
need the wifi connection , it was just for us to know what
was going on onboard. Once we set it going its then totally
autonomous. We have the original r/c system still in place as an
override. Also , in the competition, you are allowed someone in a chase
boat who could intervene if things go wrong, like crashing into something ,
other than tht you have to let it do its own thing.
We used open source stuff for the Pi, the Python language our source
code in GitHub, a www repository of it contains all our code ,
and you can see what we're doing wrong. The key component,
to make it work is ROS, the Robot Operating System, the version
we used was Indigo Turtle with ? shell . ROS principle is there
are nodes which are separate programs , running things, and they
talk to each other. One program just controls the servo motor,
one that just gets data from the wind sensor, they send out ROS
messages which the other programs can listen to . It makes it easier
to separate out the bits needed for the robot, so if the compass bit crashes then
ROS knows how to restart that , so it does not mean everything has crashed,
just that one part has crashed. A lot of people program robots and end
up re-writing everything from scratch, so ROS means you have
pre-written bits which can be shared between multiple robots
. So if we've written something that works particularly well, say
determining how to tack up-wind, then someone else could use that and
plug it in to their own sensors and things, which might use data in a different
format. But a standardised interface that lets you take and combine
different bits of code.
Q: With the sail servo , do you have a position sensor for sensing the
At present we only know how much sheet there is in or out.
So if the servo drives to one extreme, you don't know about that until
other things start happening?
Yes, the wind sensor we can see which way the wind is coming from
but in the edge cases , where you jibe, then you don't know exactly
how the sail is set.
ROS lets you define the launch file , which tells all the nodes that
we want to start. There are different launch files for testing of
calibration of sensors and then for actual sailing in ernest.
There are parameter files , containing settings for different sets
of sails , for different courses . The co-ordinates we want to go to
are programmed in , via the parameter files . ROS makes
easy ,the monitoring and the analysis. Al lvery well putting the
boat in the water and try nd make it work , but often when
you are sailing , there is no time to work out what is going
wrong. Without that, when you get the boat back , you would
not have the details of during the error performance,
you would then only have the memory contens of the boat
turning round in weird circles and would then hacve
to try and piece together , what the system was doing that
made that happen. ROS has a bunch of useful stuff to
give you more info about what the boat was doing , centred around the
tech calles ROS-Bag ? a way of recording all the messages of the
different parts of the boat are saying to each other , wind is 20deg, compass is
170deg at a particular moment, all recorded on the Pi .
Then we get the boat back , we can pull that data off and plug it
into various things to analyse it, tools like ARCU2? that can show us plots
of angles over time , a map of where the boat is, relative to markers
for the course. We also wrote our own stuff to help with theis ,
an HTML dashboard , a live view of what was going on the boat, on
computer or a phone. This was helpfull a couple of times in the
challenges, people in the chase boat could pull out their smart phone
, connect to the boats wifi , and view some of the key parameters from thr
boat. We also wrote a set of ROS nodes for simulating what the boat was
doing , so we could test the boat code without having to place it
on water every time. The nodes for the boat itself take the inputs
of where the boat is, what the wind is doing, and polls? output of what the
boat should do now. The simulation nodes can complete the circle.
Take the input of what the boat wants to do now , and then update the
posistion and heading of the boat. In the simulation we make the wind non constant , as happens a lot in reality , which makes sailing so much more
confusing than the simple diagrams of wind just from one direction,
A map view video of the waypoints the boat was going through, from the
recording of Rosbag messages along with other data to work out what the
boat was doing at that point, why it was nit doing what we expected
it to do. Sept 2016 in Viana del Costelo ? in north Portugal.
The River Lima? with a bridge designed by the designer of the
Eifel Tower. We launched from the bankside. There were 12 teams ,
2 classes ours was in the micro-sailboat class which is up to
1.5m long, 7 teams in our class, 5 teams in bigger boats up to 5m
tending to be from Spain and Portugal as large boats.
The competition has been going for a number of years, moving
each year. 2015 it was ? islands between Finland and Sweden
and 2017 will be in Norway I think. Theya ske dus if we'd like to
host it in 2017 but we felt we could not arrange that in time.
There are no physical bouys to collide with and we have no
collision detection on board. In the first day they all
sail together . You are allowed momentarily to take control
via r/c to avoid a crash. 5 days of sailing, the first day was for testing,
getting used to local conditions. We discovered that waterproofing is
difficult, electronics and saltwater don't mix well.
The part that switches between automatic control
and the r/c , liuckily we brought 2 of those as the first got
destroyed by saltwater . We aquired some sanitary towels in
Portugal to soak up excess water in the hull, which worked well incidently.
The box duct-tped to the outside of the hull , that contains the
competition's own GPS tracker, for a separate log of the boat
track, so they can score the competition.
The first race was to go round 4 marker s , the quickest to go round
al l4 , would get the highest score. Not for us though.
The second day was station marking, just 1 marker and stay as close
to the marker as possible for 5 minutes. This sounds easy on land
but whan sailing there is no stop for a sailing boat, always blown by
the wind and pushed by the current . THere was a very strong current in this river, we found on the test day. You have to keep moving to stay in
one place, like Alice in Wonderland.
Q: Any detection for current?
No , the boat judges where it should be going and judge it by that.
Q: you don't get it via the gPS system?
You can try and work out I'm not going where I think i'm
going . We did not do that as a lot of other things to do, but you could
in theory pick up some measure of the tide via the GPS.
The third day was a grid search an L-shaped grid of 27 boxes
and we had to get into as many of the boxes as possible.
The fourth day was a collision avoidance day, going back and forth
along a narrow course ajd at some point they towed a line of
big orange buoys across the middle of the course.
The boat had to detect these , swerve round them , then return
to course and continue.
By the 5th race everyone had by now discovered the current is
really strong . At the start the wind was going one way
with the current as well , so very challenging .
Of the 12 boats in that competition 2 boats managed to start
the race and one boat managed to finish .
The boat that started made it past 2 markers but failed to
turn at the third. Our boat was not at all successful.
Partly due to the current . 2 servo motors, one controllint the
sail , one the rudder and on this day we managed to plug the
rudder servo into the sail servo system and vice-versa.
We had a boat that went round and round in beautiful circles ,
wiht a lot of exasperated humands on the bank.
That was something you have no hope of diagnosing from the
computer logs, because the boat is doing everything as it should,
its entirely a hardware problem. As a result of that, we added
some code, so when we start the boat, it wiggles the rudder in a distinctive
pattern and then puts out the sail a few seconds and then all
the way in for a few seconds. We never made that mistake again, but we
did make other mistakes.
A whiteboard i nthe clubhouse with co-ordinates written
on it, lat and longitude. Most of the other boats did much like we did,
lucky for us in the overall scoring. An amazing GPS log of the French boat
that managed to finnish, because it did very tight zigzags all
the way up a few hundred metres up one side, about 1/2 hour ,
then zoomed around the rest of the course.
Day 2 , staying on station, that part of Portugal gets sudden
fogs that turn up from the river. A new meaning for getting data out of the
cloud. We were sitting on the bank, numbers coming in , but we could not
see the boat at all. For the first minute stay in one small circle around the
point and then 5 minutes staying within a circle that contains 95%
of the track. Fiddly to work out, but done by computer.
We managed to get a 25.3m radius , could enough for second place in that
challenge. THe welsh team won that challenge, staying within a 5m radius.
Day 3 , getting into the most squares, we managed a fair few of the
squares and again good enough for second place, the Spanish
team did the best there. We discovered its not a good idea to use the
launch file from yesterday , as it started off in a loop
to where it had been doing the position keeping , the
day before. The large squares were 60x60m divided into 10m
squares. Luckily they allowed us a second go, after our boat
sailed off in the wrong direction, otherwise it would have
been nul point for that.
Day 4 , obstacle avoidance. We got a USB webcam , same as
simple skiping one. Fitted it to the bow, cable running back
to the boat computer . We could look at the bouys beforehand
, so we knew what they would look like. We wrote a simple bit
of computer vision code , that basically just counted how
many pixels were orange. So we had to define the range of
colours for that orange. Then we had to decide the minimum number of
orange pixels before it decided to avoid. For the camera we had brought,
was not suited to outdoors bright Portugese sun , getting very
washed out pics from it, the solution was a trip to a supermarket
for some cheap sunglasses , popped out a lens and selotaped it
over the lens. It worked. The camera was put in a plastic bag to
keep the water off.
It sailed back and forth along 150m course, they towed the bouys into the
path of our boat . We were sitting on the bank, watching the
dashboard , a figure saying not detected, repeating , then just about
as we were to hit the buoy , detected , but unfortunately too late
to swerve out of the way . The proportion of the image , to be
orange , may have been set too high . Also they had told us the
buoys would be in the middle 50m section of the 150m course,
according to their GPS they did , but according to our
GPS the bouys were to one end of the course. Our boat had
just left the area we had set for it to decide whether or not to
swerve. We collided with a buoy. This may not seem good but it
was good enough for us to get first place in that challenge.
As the course was very long and narrow, none of the
other boats managed to stay in the course. It may have been pure luck
that our spot was just as the tide was at low tide and the current was not
pushing the boat.
Q: Perhaps you should have collision avoidance for all times.?
We have to go round bouys at other times and we did not want them
detected by that ststem then. Perhaps we should have made the
observation area more generous. GPS is very consitent with the
same unit but there was questionable GPS reading between our GPS
reading and their GPS reading. After all that we managed to get a win
in our class. If you did not managae a valid run on a given day you got
8 points, 7 boats in a class plus1. First place gets 1 point
, second 2 and so on and the lowest score wins. So getting 3 valid
entries we managed to come in first over all, which we all
were surprised by, as none of us had done this sort of comp[etion
before. We learned a lot doing this, had a lot of fun .
My take-away from this is , reliability beats performance.
That your boat works is better to focus on , than make it work well.
It did not do any of the challenges brilliantly, but it do
all those challenges, which was a lot of the scoring.
Lots of really simple things can go wrong, plug the wrong thing into the
wrong thing, you can use the wrong file misdirecting it, water getting in
because you've not sealed it well enough. We had one day when the boat
was doing something funny, the chase boat went after it , to pick it
out of the water and it was noticeably heavier because it was full of water.
This was a spare time project for all of us, we all work on other things
at the uni. My work is software, programming stuff and this project
brought home to me how challenging it is doing hardware stuff.
A whole new array of things that can go wrong when dealing with
hardware, that otherwise a computer deals with .
We will be doing it again , we returned the boat to the water for the
first time since the competition only a few weeks ago
with lots of ideas on how to make it go better.
Are you using the heel sensor data for anything?
It does get published but its not of much direct use. It does get used
in the same nodes that publish it, because the compass data
Do you have any plans for optimising for the wave condsitions?
Its not something we've done anything with yet, something we wish to
investigate more. Particulrly in choppy waves , a sa small boat
doesn't have much momentum it finds it difficult to tack.
As soon as it turns into the wind it looses momentum , loses
steerage. So we have some ideas for optimising by tacking on
the down slope of the waves.
I was thinking of sailing freer, sails farther out and lower? , to pick up speed before tacking?
We've not thought about that. Making the boat longer would help with this.
A physical solutiion to this sort of problem is often better than
some smart algorithm.
If you truly roboticed it , you'd do as a human would do and
you'd set the sails farther out , to pick up speed, so the VMG?
would be the same possibly as going furthe r, off the wind. This
happens in small human crewed boats?
We don't have very accurate velocities, just based on the GPS.
So we need a way to integrate the GPS sensor to something
loike accelerometers, to work out accurate velocity feedback.
Then that would be possible, a good idea. How to tell if the
sea is choppy or not , maybe a camera system, certainly anothe r
sensor required. THen experimenting between human observations
and trial runs to find correlations.
Do you have different sets of polar diagrams for different
sets of conditions?
When your tacking up wind , how do you decide on lots of short tacks
or longer tacks, based on how far you are waway from your straight line
course, or set distances maybe?
The initial thinking was to detect the ley lines. This is where we
found the changing wind direction makes it trickey. The wind changes
and the boat thinks the ley lines have swung out 90 degrees, so we have
some code that tries to average the wind direction. As we get closer to the
waypoint we are trying to go to, we have a thing called tackvoting?
cuts in , so rathe rthan considering am I past the ley line at this moment
it keeps a 10 second rolling count , sampled every 1/10 second, did I
think I was over the ley line and ready to turn. Once that number
hits 75 then it will turn , which has the nice side effect
then once its doing that, then it wont turn more often than every
7.5 seconds , because you want some gap betweeen your tacks,
to let it build up a bit of speed.
Do you know the French boat did this, lots of little tacks?
They were using a vector-field approach , a vector flow approach. They set
up some kind of virtual obstacle and a point of attraction ,
and between those you can work out optimum fields, and point out the
direction you want to sail. Hence that team doing lots of small
tacks all the way round, artificial potential theory, well accepted in general
robotics control) gives that.
The french boat was in a different class , about 1.6m long ,
super light , which means it can easily tack in difficult
situations. The net effect was their boat stuck much closer to
the line betweeen waypoints.
Do you have a sensor for how much the boat heels over?
Yes, from the accelerometers , sensing gravity. At the moment its
only used to corrdct the compass.
Are you allowd a second remote sensing sytem , in the water to
detect tidal current and transmit that to the boat?
I don't think in the rules there is outlawed remote sensors on the
shore or whatever. I don't think any team are doing that.
We did not have a reliable radio link either.
Could you use a parabolic dish rather than the usual wifi thing?
I don't kow what the internal geometry inside the white box , it
is long range and highl;y directional , but the range was not enough
For your servo systems do you have something more subtle
than the normal proportional control, a suck it and see a marginal
shift , to test out and then back off , someting more sophisticated
as you have a computer on board?
No, the servo control is the standard pulse-width modulation .
One thing we've been thinking about is , a human sailor will
look a tthe sail and if he sees it fluttering , you need to pull
in a bit more . Could we have a vibration sensor mounted
on the sail itself , also measuring the tension in the sheet .
So you are sailing at a specific angle to a relative wind rather
than looking for the point of flapping/luffing point. So sailing at
a conservative 45 degrees say instead?
At the moment just a hard coated? angle , a hard-coated table
of if the relative wind is 90 degree then the sail angle is x
and it adjusts within the angles it knows about.
Did you ever get involved with strategies of stealing other boats
wind or that sort of thing?
No ther ewas 1 day of compete racing scheduled, all
tyhe other challenges were individual boats at a time.
Even at the fleet race, no one was at the point of being
capable of stealing anothe rboats wind, just going in the
right direction was quite enough.
Is it the same challenges each year?
Similar each year but not the same. The organisers a the site get to
organise what the challenges are. The computer vision challenge
with bouys was new last year, replacing a challenge from
the previous year that involved collecting data from added sensors
on the boat.
You know aboout the challenges before the event?
Yes, we could practise them beforehand.
So you would know in advance they would be orange bouys?
We could do calibration with the Go-pro with real
objects on the water a tthe site, to check our coding
recognoises the object.
How many algorithms have you got running?
Each line with a node is one bit running, so 15
to 20 things running .
That is the tasks, but the algorithms to interact , data from
multiple sensors , an algorithm to manage that?
Each sensor has its own thing pulling the data from it, there is
really only one core algorithm that is deciding where to go next
So one algorithm taking all the dat ain and deciding how to
set the sails at any 1 point in time?
Yes, try to go in this heading and the sail control
goes separately, keeping track of the relative wind.
Its smart enough to know it cant go directly into the wind
and different tasks that can switch in, what should the boat be
doing now . A different bit of code for the obstacle
avoidance for example.
They always choose tidal rivers and not nice quiet reservoirs?
The previos year it was in the Baltic Sea,next year will
be in Norway presumably a fiord.
If you don't use the heeling sensor , could you not turn it
90 degrees and use it as a pitching sensor. ?
The accelerometer is 3-axis so we have pitch as well. So pitch
and roll off that , not yaw. It gives 3 acceleration readings and
we convert that to pitch and roll.
How long did you spend on the project?
We started in Jan 2016 and the competition was in Sept.
We had meetings 1 evening a week and occassional weekend day
of working on it or testing it.
Apart from being a bit of fun , is there anything to be learnt
for sailing in general.?
A challenge called Microtransit , a boat smaller than 2.4m
, must be wind-powered to sail from the UK to the USA .
Loads of people try it every year , but no successes yet.
If we got a boat like 2.4m , what can we di with it. We can
collect environmental data , monitor sea levels, check
water quality and waves across the atlantic. Wind energy
is virtually unlimited , no fossil fuel consumed.
We're not advancing humanity at the present stage bu tin
the longer term, we open source all the projects, to anybody
interested . We could monitor fish populations, water quality , that
sort of thing. It would be interesting and cost effective.
All our kit costs are second hand boat about 200 quid and all the
electronics add up to no more than 100, the Raspberry Pi
at 30 quid is hte most expensive bit, all hobbiest sort of stuff.
Are you satisfied with the data from entry-level kit?
We've stared with envy at a much higher quality
accelerometer on display at Ocean Business at the NOC
recently. All sorts of hitec gizmos. A lot of the stuff we are happy
with . We are currently trying to integrate the GPS
and accelerometer so we have a speed reading.
Do all the teams share their data and ideas?, perhaps
binocular or sonar for instance?
One team was doing a sonar thing, not underwater but
ultrasonic in air . Sonar under water there is so many
reflections . Most teams were like us with a camera on the
Do the rules permit wing-masts and hydrofoils?
I think the rule was anything as long as it was powered by the wind.
A wing-mast might be simpler to control than a pair of sails,
a double-sided sail wrapped around the mast?
A couple of teams did wing-sails, so allowed.
A Flechner Rotor type thing that required mechanical power to
rotate the rotor , to then grab wind energy, would not be allowed?
You're allowed a linkage from a wind-capturing something like a
propellor, as long as the only source of motive power is the wind.
Have you any contacts with the big-boy autonomous , huge trading/cargo
sailing ships that are just coming off the drawing boards, multi-mast and
huge sail arrays but just 1 human on board ? Wherever there is reliable
trade winds around the world.?
We must share something in common, in the way of the control
systems , but have no direct contact.
You've not found any use in conformal coatings over the electronic
gizmo boards, just waterproof boxes?
We did use Plastidip on some of the electronic boards that gives it a
kind of waterproof coating. More recently we were told of stuff called
Magic-Gel. You put your electronics inside a box , fill it with t he
gel , goes solid and is not conductive. Its a bit like Argo-Floats and
immersing all the electronics in oil , so nowhere for the water to get to.
Wondered if you hada problem with consendation as much as seawater
We've not had condensation problems.
Do the organisers allow you to see their GPS system beforehand,
as you said yours and theirs were different? A fixed offset all the
time or varying?
There was nothing secret about their GPS. We didn't get to
look into it as their boxes were taped shut. As there was something like
30m difference between the two in the collision avoidance
challenge, it may be sensible to place their system and ours in
one position , prior to the race next year, to check for any offset.
Were the grids the same for the different classes?
I think the bigger classes had bigger grids to search, 20x20m grids ,
we had 10x10m boxes.
We're the bigger boats better at the tasks?
In some tasks yes, not necessarily due to the size of the boats.
Teams bringing bigger boats were possibly better resourced,
more experienced , like the French team.
Generally the bigger boats wwere better at picking up speed
before tacking and the speed is relativw to the boat size.
The Froude number is much larger for the larger boats.
What are the challenges to get one of these such boats to cross the
Atlantic, just funding for a more robust boat or?
Getting a tiny boat cross the sea has many problems. We know of
a boat being kept by some fishermen, another attacked by a shark.
Some the servos did not last even 24 hours, because of severe sea
conditions. Waves of 7 or 8m with a boat that is only 2m , not nice.
There isa team near London that launched a mircotransit
attempt from this area , got into the channel but with the tides and
things it never got out of the channel, just being pushed back
and forth, and eventually washed up on shore.
You need the endurance of power for the computers as well.
We currently use a USB power-bank that would otherwise be used to
boost a mobile-phone power, works well. Alsoa set of AA batteries for the
servos. The Microtransit boys have solar panels on theirs and
batteries so it doesn't die in the night.
Just the ability to keep going without stuff breaking ,
for the lenght of time involved and make headway against wind and tide
and big waves. A number of teams start out each year, west and east
going across the Atlantic and so far no success.
How does the robotic control fare against human control, say via
When everything is going smoothly , then the robotic is comparable to
someone without much experience of r/c sailing. A good r/c sailor
could always beat our boat.
Monday 12 June , Dr Roeland de Kat, Soton Uni : Forces and
turbulence in avian flight .
27 people, 1.5 hours
Over about 10years I've done bits and pieces on avian flight.
Today I'll talk on forces and turbulence. A lot of this work
has been done with David Lanthing? who now has his own lab
at Stanford. I'll squeeze in some Par-avian flight and finish
with avian turbulence. The main reason I'm into this , is because these
little creatures are amazing. You see them flash by and you don't fully
appreciate what is going on . I spend a day with a high-speed camera
chasing gulls on Southampton Common. A 400 fps video of one in slo-mo,
flares off, stops in mid-air, drops down seeing something I could
not see , takes a fish in the beak and goes straight up and out.
A lot of things going on there and a lot is beyond my expertise,
thata why we need to work with different types of people.
My background is aero-space enginering and so I can figure out
some of the elements of its flight. A pic of a swift, amazing
fliers. David Lanthing picked the swift because of its intermittant
flapping and level flight. As soon as you see something flapping,
engineers and biologists say thats way too difficult.
So we need to know a bit more about what is happening.
One thing David observed, in seeing them fly , they change their
wings, have them spread out or swept back. I was doing my
masters in Delft and David asked me to work on this, swift flight.
So we looked at morphing wings, how they control the glide
performance of swifts. What are the forces that act on the wings
, how the forces change as they change wing shap[e and what does that
mean for flight. We both had engineering backgrounds is the gait?,
thats not right 5 degrees, 50 deg , its meant to be 0 degrees,
60 degrees. But somewhere in the process of removing the
body of the bird, freeze-drying the wings, the wings did something by
themselves. When we put the wings in the freeze drier , they thought they
had them at 0, 15,30,45,60 degrees, but we needed to quantify it.
So part of the wrist , the sweep angle and that changes. We don't always get
what we want. A colleague a true biologist , we said to her this is not
true 0 degrees , she said its within 15%, that is biological variation it
explains everything. We went about quantifying different sweep
angles and a few other things we care about when talking
about aircraft and flight. The aspect ratio , generally linked to
how efficiently the wing performs and the wing area as the bigger then the
more lift produced. Classically these are just parameters; you pick,
you set and then forget about it and design your aircraft. Our flight
machine includes multple wing areas , multiple aspect ratios .
The first tests were forces, classically drag and lift , we want he
highest lift possible for the lowest drag. If you want to compare
a swept back wing to a straight wing , one bird , one wing ,
can change it. So instead of going at it , like an engineer and
normalising everything into non-dimensional things , we need to
take into account , it can change its wing area. If you put the
wing area back into the equation , then you see the differences between
the different stances becomes much larger. The envelope
plot , going from wings straight all the way to swept back.
If you change the flow velocity , keeping the medium (what is
flown through) the same, keeping the size the same , change of
velocity changes the Reynaulds Number, the paramete rthat tells
you how difficult it is to deal with the flow. The higher the Reynolds number,
the more complex the flow gets. The lower the number , less complex the
flow gets. If you add particles it may get more complex again ,
one of my colleagues work there.
Adding this in , we have to take into account , this occurs in a flow
regime , where things change. They change from lamina to turbulent .
If we add those different velocities int play, 5metres per s to 30mps, cranking
up the wind in the wind tunnel, the dashed envelope line , changes
further. We can scan the parameter space of what we expected these
birds could do. A bunch of numbers, that don't necessarily
mean anything . We took those numbers and put them into a glide
model. They are flying in different poses and we know trhey
are fully balanced. We have the lift and the drag from our
equations , an estimate for the weight , then say if it flew with this
velocity what can it do, and at a different velocity what it can do.
Not just a glide but what if it flies in a spiral. Swifts swirling across
streets , they glide and like to turn rapidly as well, quickly
changing their sweep angle.
Generally in aerospace engineering , we ignore a few things. Generally
we say gamma is small , a small angle, so we can neglect a whole load
of terms. But we needed this , to fully describe bird flight.
Equations , looking at performance indicators, how far forwards can it fly
with a 1m drop. Or 1m down , what is the slowest I can go down. The sink
velocity , the glide ratio. Maybe it wants to escape a predator, maybe you
want the ground speed to be the highest. Then some turning velocities
and performances as well. Whats the largest turning angle we can
get per m of descent, what is the tightest turn we can make , wha tis the
quickest we can turn. Below 45 degrees , gacefully falling , about 45 degrees
gliding ? flight. An easy cut-off , 45 degrees. Most follow the
same trend efficency peak at the lower velocities. Anything more on
efficacies or group-power can peak at the higher velocities.
Looking at the glide ratio, we can already see a few interesting things.
Peak is exactly where we expected. At undergrad level aerospace , for
straight wing, highest aspect ratio , is the best. Glide ratio of
about 11 . Estimates for albatroses don't go much higher , 15 or so.
So a pretty good glider. As we increase velocity , straight wing is
not the best any more. Initially this was a surprise, why is that happening.
Looking a bit closer into this, that is what we could expect.
If you take into account , the area of the wing, wing area changes.
Return to the curve with high lift, low drag, that needs to balance with
its weight in flight. Increase velocity , the coefficient goes down ,
poorer performance. As we go to swept back wings , performance gets
better again . Performance improves at higher velocity
purely due to the area change. Change your area, you can stay at the
better performing part.
Q: Does the angle of the wing vary over the wingspan as well, in this change?
Likely. But thats an additional challenge, not included in this
presentation. We looked at the deflection of the wings, from the
rear, at different velocities and they do deflect a lot. Lots of pics show
that swift wings a pretty well planks as wings , not a lot of
twist present. With our prepared wings, the twist was not
big enough to quantify.
Q: When you say whan the aspect ratio is very high , it changes the
wing area ?
Wing area plays role as well
Q: But on an aircraft , wing area is always the same, irrespective
of sweeping the wings back , so why is this different?
THe feathers overlap , when they start overlapping more , the
area changes. The benefit is, instead of having the small
difference between straight and swept back wing, here there is a huge
difference because area plays a role. At equilibrium balance at about
7mps, if it goes faster and faster , there isa curve that says
, equilibrium is lift^2 + drag^2 = weight^2. When that moves down ,
it shows how swept back wings perform better at higher velocities.
But does it really fly at those speeds. We tok data from a
different study Beckman & Alistahn? , the most probable flight
velocities, the most observed flight velocities.
The velocity swifts are recoreded at , fall in this range , and fall
in the range of all the efficiency parameters, not the efficacy parameters.
A lot of measurements , a lot of observing a wing in a wind tunnel
doing nothing at all, for about 2.5 weeks, 9am to 3am, very
tiring . Now for the vortices. If we take these wings , placed in a
wind tunnel, what I found intriguing , sold me on it, we have
leading-edge vortices. Before I started my internship 2004, showed
on a model wing with vortices. But engineers would say in the
1950s we had such vortices on swept back wings. Something else with
wings may have a role, they are porous. So do the LEVs make the
wing more efficient. We need a way to capture them and measure them.
So took a tin can, cut a hole, weld something into it, take a cigar,
put it in , high pressure air added . have a rake on the other end,
hold the rake in front of the wing, puff the smoke and you can see
the vortex. That failed miserably because cigar smoke is very
moist , a lot of tar, so imediately clogged up the tubing.
Trying loads of things, took a tuft of my hair and we used that to
visualise the flow. If you see rotation, then the flow is pushing my
hair around, ie a vortex. You can follow it into the tip vortex ,
the key is it started turning in the position of a LEV.
So we logged , moving of the hair around and whether we saw
rotation or not. Pictures of where there was a cone and not a cone,
and showing , for the rake used, it does not create it by that and what
we were doing. So there were LEVs but not present in any of the cases
where there was peak efficiency. So wherever the swift flies most
often , there is no LEVs. Where it did show up and where 1950s
engineers designed it around as well , you have increased efficacy.
A peak lift that you can create , you can turn very quickly .
If in a dog-fight or chasing insects , and the target goes off in one direction
, you need to go after it. Thats where it comes into use, where they use their
LEVs. We've only touched the tip of the iceberg of research
into bird flight. A lot of current research into capturing what living things
do , and build them ourselves.
I moved to Soton, to look at turbulent boundary layers and develop
experimental techniques. The first thing I looked at was a feathered
dinosaur. So a small dinosaur and similar approach to the
swift research. Take a model, place in a wind tunnel , get forces,
make predictions as to what it could do.
From the fossil record, such creatures are flattened out, feather
material . So a crow of its day, irridescent feathers , but could it
fly, how well did it fly. Some previous researches CL of 1
sounds good , glide ratio of 15 sounds good, combine and a very
good flier. So a colleague Colin Palmer found a pigeon in his yard,
bought a duck and created a model. A long tail, feathers on the
legs, and feathers on the wings. Whats this with hte legs.
Paleantologists bamboozled, perhaps everything was spread out.
Some people whan young can put their feet behind their head,
projected reasonable extremes, given the bones, what it could do.
Legs sprawleded or legs down and asked does it fly.
We put it upside down , because the balance in the wind tunnel is
at the top . 2.5 x 1.5 m with the animal in there of about .6m span.
Something at the rear thtat pushes it up and down, changes the
angle of attack , little weights and servos to capture the forces.
Lift and drag as before , but this time we add the moment.
With centre of gravity and moment at non-zero , it will
rotate. We wanted to make surre that whatever we say it can do,
as it doesn't turn like a leaf and roll or flutter down.
So the moment about the cofg needs to be 0.
We tried to measur ethe moment with the earlier swift work
but we failed. Luckily there are plenty of accounts that
swifts can fly and do so without their tails spread, in the vast majority
of poses. For swifts we could ignore the tail and it was fine, the findings
not affected by not having a moment.
Other researchers avoided this also, saying there were various points
it could fly. We accounted for it , with speed specific dynamic force
, which is basically the total force and then splitting into lift and drag.
The glide ratio, speed specific moment, and regions where it could fly and
some areas where it is not stable. If it moves up, makes the moment
larger , keps moving up and you get a confetti effect. To fly there
it would need a big brain, which is up for debate.
Elsewhere it is stable , not requiring a brain, and just jump out
of a tree and fly.
So jump out of a tree, make your pose and see what happens.
With fairly simple assumptions you get to glide paths. Initially showing
legs down is clearly better than legs sprawled. Then the engineer comes in
and maybe it could move its arms back and forth, so we need to
account for that. We modelled that by saying it could move its cofg
wrt the lifting surfaces. That tilts/ shifts the moment up and down .
As the big/small brain debate is still ongoing, we just say there is an
unstable part and a stable part. If small brain and not a good
flier , it can fly in that section. With big brain, advanced controls ,
it can fly there as well. Stable areas, no thinking required, areas where
it could glide but needs to work hard. Compare the 2 plots and
its not that different. Jump out of a 30m tree , glide-path, if you want to go
farther with legs sprawled, we think it hasa bigger liufting surface.
Go to the side, with the wing feathers, it goes up.
I started loking at turbulent boundary layers TBL on bird wings.
A flat plate is boring com[ared to a bird wing. We thought
behind this was some meaning as to how flight evolved in
feathered creatures. A wing is not a flat plate, the feathers overlap,
and in the overlapping there is a roughness. Feathers are not all
smooth or not flat at the top. To get a good force out of an
aerofoil , first year students are told it needs to be flat, a sealed
plane, flattness 0.000 something % flatness. So how does the
roughness work here. The lakidys? with the veins around it.
Shone a laser with lens in front, take a picture and get a cross-section.
Fairly smooth and as we move outwards, gradually gets more
corrugated, looks more like a dragonfly wing than bird wing.
They fly much faster than dragonflies , a different flow
regime. Measure them, abstract the average curvature , because it
has nothing to do with the surface roughness, colour code the
height , then compare that to the average chord, about 37.5mm
, peak to peak it is 0.8mm , 2% of the chord instead of those zeros something %.
So very rough, it must have an effect on the flow, must be fully
turbulent. So wing in the wind tunnel , to find where it is
turbulent flow and where it is lamina flow, skip the bit in the
midddle as too difficult to deal with, but there is something other than
those 2 flow regimes. If we used a hot-wire as for measuring velocities,
it would probably cut the wing. Use smoke and you might create
a wet wing, very different to dry birds. The best thin we came up
with was a microphone, with a very long tube on it. Build it right
and its only sensitive to pressure fluctuations at the tip of the tube.
Traversing the wing , patches of single pitch
noise , not turbulent. The hissing sound is lamina separation .
So we move our listening tube along the wing to find whare the sound
changes. It does not change randomly as turbulence is
quite well defined i na broad band signal. The tonal noise we were not
sure what to with that , I'll come to. Put it in Fourier transform
analyser and you getr what frequencies in there, high low, broad or nothing.
You look for where there is extreme change, that is where we go
from lamina to turbulent. Mark with dots where the changes are, do the same
thing for 4 angles of attack, times 3 wings. We take 0 , half way and
maximum lift to drag, which is whare its interesting. Also where there
is maximum lift , or stall , whare you'd expect changes to happen.
So we locate where the changes are, but thats not where the
roughness is. Where the roughness is, no transition .
Everyone tells you , going through aeronautics, wheere its rough
there is transition to turbulent flow, the worst thing you can do to your
aircraft. Swifts don't care about this , they just do their own thing.
Flow is not changing instantaneously , turbulence is not
something , clicks over now lamina, now turbulent.
There is a transition process, in one place with a certain Reynaulds
Number, transition may only occur later on.
So an area with lamina flow , and whaet
that means for the bird.
For different angles , its primarily lamina. The peak is almost 75%
lamian , or at least non-turbulent, where it wiull perform its
best. Thats where it flies most , unsurprisingly. How do we
know its not just a thing with swifts. How do we know its the
roughnes, by testing. The swift wing , with calipers trying to find
where the ridges and valleys are, then I used a laser scan.
We built a wing with thin pieces of tape attached. It has one
width and tibs and one without. We used the listening tube
again on this. The rough has more lamina area than the smooth,
low reynolds numbers. As we increase velocity we get
back to normal. Big aircraft with big Reynolds numbers,
flying fast. Aswift isa small bird , fast in bird terms but slow
in airliner terms. Right about the range where these birds fly ,
rough wings are not bad, in terms of lamina area.
What does that mean in terms of performance. Mor elamina
area means better performance, not necessarily.
Our wing, lower reynolds we do get bettewr performance.
What is going on in the flow, we still needed an answer.
A masters student in Delft took the roughest lines measured
profiles of the wing, averaged them , measured under a microscope
the leading edge radius of one of the feathers , estimated the thickness,
to produce a 3D printed model. Then remove the roughness, make a smooth model, 3D print it . Now anything you machined
or 3D modelled will be as you intended it to be.
Its not far off. Placed in a water tunnel. Luckily a low velocities
, air behaves as water , as long as you match the reynolds numbers.
With water, the forces are 4 to 5 times higher, so easier to measure,
or so we thought. 3 cameras looking at it, placed a load of
particles in there , watch where they go and we get velocit y
fields. We tested 3 angles of attack, for 4 different reynolds numbers
and the range where we expected changes to happen.
Not much obvious differences. So w etook snapshots , summin g
and dividing by n . Looking at vorticity, so
rotating 1 way or the other, or shear. Low angles of attack nothing
there, intermediate angles a little hint of something there,
high angle of attack , definitely something going on .
Vorticity is not too natural a thing to look at. We zoomed into
small area and looked at vector representations, much easier to
interpret. The vortices that get induced are the
tonal bursts you heard on the video recording.
Vortices move , they're periodic. In the global view we might not see
it. In aeronautics we reduce it to a bunch of numbers, describing what the
flow is doing. Boundary layer grows as it goes over an aerofoil , it has a shape
and it can be quantified in multiple ways. Generally we pick
boundary layer thickness, about 99% of the external flow.
Then we can determine how much velocity you would need , rathe rthan
a curve , you make it a straight line, the displacement thickness.
Then you can work on how much energy is lost.
With the boundary layers , you get an inflection , a separated
flow , flow is not attached for poor performance.
There ar efluctuations around the average profile. Boundary layer
thickness. not much difference rough or smooth. The shape
factor , one of the indicators of whether flow is turbulent
, lamina or separated. The bigger wake is generally
indicative of a separated regio n as well .
For the rough, we get vortex trains for intermediate
angles of attack where peak performance is.
Low angles of attack, no vortices , lamina flow over a rough
wing. High reynolds nubers, they both go turbulent.
For high angles of attack , smooth and rough wings are little different.
This is where a swift wing performs and a smooth wing does not.
The beginning of the wing, kicks the flow , it gets agitated and stays
attached. It does not separate , it follows the wing.
Although turbulent flow is bad in causing drag, its a lot
better than having a separated flow as that would mean
I have a PhD student also interested in feathers but he comes at it
from a different direction , as a biologist. So we loooked inside
feathers. Taking a swan feather to pieces , placed in a
syncratron a large particle accelerator . The particles shoot through
the feather and a scintilator , turning radiation into
light and look at it with a microscope. Move around 40
times. The core has a patterning , but move to
the outside no patterning. The material properties change.
Also there are multiple layers in a feather. So beyond
avian aerodynamics , one of the most
complex advanced composite structures i nthe world.
So the next research is trying to determine what the layers are, which way
the fibres are pointing . We could then model the composite, tear it
apart again, and see if we can tell something about it.
Hopefully allow us to build better structures, maybe improve
small-scale flying objects, wind-turbines or whatever.
You said the wings were porous , so with bats where its just a membrane,
would htat behaviour be more like conventional aerodynamics. ?
Feathers are porous but for most lifting purposes
We try to model the porosity , and we failed. Wheras swift wings
use roughness to keep the flow and keep the flow
attached, what membranes might do , is changing the camber, the
curvature and more lift, but it vibrates more.
With a vibrating membrane, it does the same thing as roughness,
energises the flow, it creates vortices , keep the flow
attached. A completely different phenomena but the effect is the
How much air goes through the feathers.?
There are people that look at the permitivity, its very little.
The latest model I've seen , they've tried to 3D print .
From the bones you have the feathers, from the radius? you get the
barbs. Optically it would seem to be porous but when you pressurise
it , it tends to flap and close, and closes. People apply pressure
differences , to see how much goes through.
They try to model that in 3D printed wings, by creating simple
holes, and they are not the answer ,as the flow goes through,
resulting in fully separated flow. There is some work on the outermost
primaries of storks,where there isa hole and the rest seems closed
, if they close that gap with wax , the feather which is a single aerofoil.
performs worse. Little holes may have jets emerging, that may keep the flow
attached on top of the roughness. But that varies, species to species and so
many species out there, its difficult to say, this is how feathers work.
There is likely some flow coming through, its too small for us to
With the albatros , a high aspect ratio?
Its about the same as the swift.
Can the albatros change the shape of its wing, for more speed?
The albatros has a little ligament in there, places it, and it locks.
Without any effort it remains straight. Swifts have loose wings, and they
have to force it. Different species have different mechanical
solutions built in, to help with their flight behaviour.
The albatros flies much faster than the swift, bigger ,so its in a place
where it will not benefit from a rough wing.
A barn owl flew in front and across me , one dark night, with a
wingtip just 1 or 2 feet from my head, and I did not hear a thing,
whats going on there , a very downy wing surface?
Multiple things, the easiest one, its very slow.
Slower means less drag nd so less sound. The second is flexible
wings, the feathers are less rigid than other birds, so
creates less or lower tone. The design is such that it gets the sound
generated but out of the range of hearing by its prey.
There is sound , just that its not audible to humans. There are
pressure fluctuations, but they're not audible.
It has a velvety surface, the precise texture is difficult to say.
May have some porosity ads well , so the pressure passes through
it rather than creates sound. It has a large wing and so a low
So infrasound or just sound below our hearing range?
Found a journal article, "Features of owl wings that promote
silent flight". They say the shape changes, wing area is large
compared to the overal bird. There is a little serration at the
leading edge, that probably creates vortices that keep the flow
attached , as separated flow makes sound, and any unsteady
flow makes sound. Another article measuring the sound from a
wing at different frequencies. One of the influences is the
comb, the serrations, of the leading edge. A lot of people
are interested in owls as they desire to reduce noise in other
areas of flight. They use an acoustic array, a bunch of
microphones and arrange flypasts. With some maths you
can reconstruct where the sound may have come from
at a particular frequency. Repaeated with different types
of birds. There was a BBC doc on the silent flight of owls,
where they compared 3 of them flying around.
Everything in biology is designed towards a goal, but its always a
trade-off against other things like mechanical structure .
Do you feel the roughness of wings is an exploitation of the
fact they've not managed to evolve smooth wings or do you
think it was very deliberate selected for the ideal shape or some
combination in between?
In the water tunnel experiments the forces were comparable
between smooth and rough wings. So if you don';t have a penalty
for hving a rough wing or in some cases it may be beneficial
for performance, then its always better to have structural elements
that have some bulk , in the direction of loading , rather than a flat plate.
So probably why little bird-like fliers, millions of years ago
might have taken advantage of having something strong enough
, but still bulky , without losing too much aerodynamic performance.
Its not necessarily driven to that goal as the main thing that
drives evolution is where is my dinner and I need a mate.
When you can satisfy those 2 , then you're good enough, or maybe
escape predators. That does not mean it drives for perfection ,
drives towards suitability for its environment.
One thing that peaks the swift , is they are pretty much always on
the wing, eat, sleep and have sex o nthe wing. Only landing to
sit on eggs or feed the offspring. After first taking off they fly for about
3 years before finding a nest.
How do they sleep?
Like dolphins , brain one side off , one side on
On the opposite side to noise , one thing I've admired about
swifts and swallows is their ability to just turn on a sixpense i nflight.
The onl;y fixed wing aircraft I can think of that does anyyhing like it
is the typhoon and even that cant turn as quickly, for the speed its
going at. Your research on angleof attack and roughness and
sweep-back , does that account for the fact they can turn so swiftly
at its speed or is there something else going on? eg can it stall
one wing and produce maximum lift on the other, in order to
turn as quickly as we see it do?
It might be able to do that, but it might be able to do
better than that. Someone buit a robo-swift , mimmicking what it
does. It uses asymetric control and move. I-morph / Bluebear? systems
, uses a similar structure to move the whole wing, what they don't change
is turning one up and one down and turn like a corkscrew.
So fly the plane sideways . If you end up turning on your own axis then
you do have to use fifferent angles of attack . What they seem to do is
swept back in dive , flare-out completely, catch up a bit , tail full
out to keep control and then continue. So if an insect made a basic
manoeuvre it could pounce on.
Some of turning-on-a-sixpence may be an illusion because they are moving
really fast, take it out, and may be more of the curvature of a football.
Its difficult to tell at a distance, we just see it turns.
When tohe paper on leading edge vortices came out , 2 of my
colleagues wrote a commentary, turning on a dime. Instead of comparing
with the typhoon they compared to the F14. The F14 has very different
reasons to sweep its wings, than swifts.
The hole in the stork wing, is the hole intentionally there?
Slotted wingtips with spread out feathers , you can treat
them as single aerofoils , rather than needing to worry about
how much they overlap . Take one feather, place in a wind tunnel
and see what happens. A little hole just before the turn .
They tested by closing those holes with wax and find the difference.
When there are holes in the feather , it performs better.
So it comes down to , a bit of passing air might be beneficial.
Its not that dissimilar to when we take off or land.
Take all the slats and flaps out, there is more air going through .
Probably tested at one speed only. Not just wind tunnel tests
but stuck it on a car and drove at thre correct speed, to make sure
the ? speed turbulance was not affecting the result.
The reason behind that is sound, even if it sounds odd.
Have you looked at commercial applications of your research?
What is of interest right now is the morphing wings,
lots of different people. My interest is not necessarily
commercialisation , just figuring out what is going
on. With morphing wings we know it performs slightly better.
It can do multiple functions at the same time, but the best design
of how to malke it better , we have a masters student looking into
right now. What strategy of morphing wings is beneficial for
performance. Also the composite structure has potentials.
I've heard the albatros is the most efficient animal in the world,
in some sort of terms. Is there some sort of a ratio between what
birds have achieved and the most efficient human wing ever developed. ?
Roughly speaking, the faster you go , staying below mach trans-sonic range,
the more efficient wings become. Humans can make wings that go much faster than birds
so they are more efficient.
Its a bit comparing lemons and pears. A human built plane will
weigh more than a bird, but for an equivalent speed to weight
ratio , how are we doing in comparison, to evolution?
Go down the scale from birds and bats, to insects. Everyone is
raving about flapping wings. Except they forget one thing, did you
try swimming in molasses. They need to do that , as there is no other way they
can fly. It doesn't mean its efficient , it does mean its the only
way to fly. For biology , sometimes, its not a matter of flying the
most efficient , its flying enough to get you eels . Flying enough to
have the edge. For the microraptor it is probably the equivalent
of a flying squirrel today, just flies from one tree to the next.
I notice bird wings seem to shed water with remarkable efficiency,
water off a ducks back?
Depends on the species. Owls can't fly in rain.
The wings don't function because they get water logged.
The cormorant needs to dry its wings , to fly well.
Some underwater flying birds don't have oil, don't preen
the feathers with oil, because it makes them too bouyant.
In bad wether owls are grounded. Probably due to
extra weight and destroying flight characteristics.
They have to wait until it gets dry. In dutch we call them
church owls because we first noticed them appearing
in churches rather than barns.
Birds fly slow compared to things we make , considering
dimensionless numbers, is there something that charactises the
different regimes slow flight v fast flight . Do wind-turbines come
under the heading of slow flight or are they fast?
To characterise what the flow does, is the Reynolds number,
has the density, the velocity , a length scale divided by viscosity.
Viscosity is water v honey . The bigger it gets, the higher the
Reynolds number , the more chaotic the flow becomes .
Or in terms of TBL the reynolds number is the ratio beteween the
largest scale and the smallest scale, how complicated the flow gets.
So fly very fast if very small and still have the same
Reynolds Number. Go very slow and be big and have the same Reynolds
Number. So take a F1 car , scale it down , put it in a wind tunnel
, you need to run the tunnel faster , to match the flow conditions.
So swifts are at the wrong end as they are small and slow ,
but luckily there is a lot of interest in micro-air vehicles,
drones , UAVs .
Monday 10 July 2017, Dr Tony Curran, Soton Uni : The Carbon Footprint of Food
36 people, 2 hours, audience interactive competition sections not transcribed
The burger apocolypse. A graph , on the x axis how many C tons you can
potentially save by doing different interventions in your lifestyle, to reduce
your impact on the environment.
so changing your diet, saving about 2 tons of your C arbon footprint (CF).
The average CF is 15 tons per year in the UK. The y axis is how much
money you could save. Its more than any other intervention like changing your
transport , how hot your house is.
What would be your perfect burger, typically its a beefburger, by
sales anyway. The Heart-Attack Grill , in the USA, their slogan is
taste worth dying for. They use it as part of their marketing, that
people regularly get hospitalised , directly from their restaurant
because f the food they eat there. They have the bypass burger,
very big. The double bypass burger , the triple and quadruple bypass
burger, 10,000 calories, 4 to 5 days foodworth for the average human.
This is Las Vegas ,sin city, so they now do the quintuple burger and up
to the octuple burger. If you want bacon on it , not a couple of rashers but
40 added to it. When you go in you get weighed and if you weigh in at
over 25 stone or 160Kg you eat for free, the American dream.
Its become part of the UK culture, steak nights or burger challenges
and overconsume especially meat . It didn'y used to be this way,
now its trendy. Leading to a lot of negativ econsequences, both for the
environment and human health and also financially.
The environmental argument. Beef cattle like lamb, are ruminant
animals, the digestion process means they generate a lot of
methane. About 34 times as potent a greenhouse gas as CO2.
It also takes up lots of land and lots of water, about 70% of
all the water we use in the world is for farming .
in terms of land about 3/4 of all deforestation is driven
by forest clearing for soya production often, to feed to cattle.
A graphic of the weight of all the animals on the earth, section
for all the humans, much larger section for al the cattle we keep
for our consumption. Also the lambs pigs,horses and then marginalised
is all the wild animals. We've pushed out wild animals by monopolising the
earth for our own ends. Maybe we could reduce how much beef
we eat. There are some trends to move to a lower meat diet, compared to
2006 beef consumption will go up by 95% by 2050, largely due to
a more affluent China.
Businesses and governments habve a roll to play but individuals as
consumers have a bigger roll. So the ABC of low-C eating.
A = Avoid wasting food, about 1/3 of all food produced is wasted.
That is about the same in the UK or globally, total food waste, in the home and supermarkets, about
7 million tons pe ryear in the UK. Globally 1.3 billion tons yearly.
How much do food safety laws impact on that statistic, sell before dates etc,
or the seller is liable to legal proceedings?
Yes directly and also indirectly as people will throw away food that is
perfectly healthy, just because of the date on the packet, I'll return to this topic.
most of the food is wasted beyond the retail point, mor ein the home than
in manufacture or farms or supermarkets, about 20% wasted in the home.
So if we go to a supermarket and buy 5 bags of shopping we effectively
chuck one of those bags into the waste bin.
Half a ton of CO2 equivalent for the food that is wasted. About 28%
of all the agricultural land is used to grow the food that we throw into the
bin. Considering we hope to feed 9million people in the next few decades.
Again huge amounts of water used on this thrown away food. Valued at somethong
like 5 billion GBP per year.
B= Buy in season food
The CF of a lot of fruit and veg can be 10 times higher i nthe off-season.
A lot of people say buy local, but the research I've done is whether it is
in seasoon is more important for CF .
Take the example of bananas, come from 5,000 miles away , but tens of
millions on a single ship and so lowC. The same with oranges from
Spain. So both are healthy things to eat all year round. Don't tell
people , not to eat them, just because they are not local.
Spin that on its head and consider strawberries, between April and sept
are in season . Fine to eat, lowCF, cheaper , tastier and perhaps more nutritious then. Out of season probably hot-house grown
in Kent, using artificial heat , so way higher CF than bananas from
5000 miles away.
April to Sept is a very long season, I live in a strawberry growing
area . Growing them under plastic in April and Sept monthes must be a
lot more expensive than just eating them in June and July?
If you use polytunnels , yes it would add something to the CF, but
little compared to artificial heating. but it will extend the season,
the same with tomatoes.
Conversely take the example of asparagus. It is atiny growing season
about mid april to end of june. A week ago i na supermarket , some was still
from the UK. Go now onwards , all the varieties of it you see all the
way to april next year , they will be grown in Peru.
Because it perishes quickly , it will be flown in , so the CF out of season
is about 30 times higher. Enjoy them in season, then eat something else,
there is always something else in season.
What if the season was not july, i've constructed a food
seasonality chart, along the term each month of the year.
Look down and see what fruits and what veg are in season in that
month. Place the chart, downloadable from
on your fridge, also the interactive games are on that site .
C= Choose low CF food more
Its difficult to know , often , which foods are high and which low CF.
Between 20 and 30% of all greenhouse gas emissions are in growing
our food or in the food system. Its the area we can make most savings
, relatively easy, without masssive lifestyle changes.
70% o fall the fresh water we use , is for growing our food
75% of all the deforestation is driven by land clearance for
agriculture. So if we change the kind of foods we eat, we don't waste it,
then we can make big inroads into reducing these numbers.
For many years I've been involved with economic developement in
the third world. They earn a lot of money exporting products to the
UK. So if we moved to a more basic lifestyle, cutting back on imported
food, grown in the third world, we are reducing their economic take.
How do you balance those 2 things. ?
There is no simple answer . Its much more general than just
food. We are a global economy now and such things will have
consrewquences. We can reduce our effects on the environment is
be a bit more local, in our production. In my ABC
, biased towards seasonality rather than buy local . If we have a
big transport footprint , millions of bananas on a boat , which
will be producing greenhouse gases, more so with flying.
Articulated green trucks , in the future, interesting to see how
that develops . In the near future thats not a solution.
We should not eat the same foods throughout the year , but have a seasonal
diet and then local products?
If we go back 100 years, or 70 years, wartime, nothing
was wasted. Most of it was local and self sustaining. People grew their
own food out of need, and was a low CF lifestyle.
Wouldn't it be great if we had urban food growth, self sufficiency
i nthe local economy, it would be low CF, the greem ethic.
Thats true and would be nice if we had it, but its not the
reality. We're moving to 9 billion people, becoming more urbanised
population . We don't have the space and most people don't have the
inclination to grow their own food. Hence we will still be
dependent on a marlket system. We have to be carfeul how we do
that and mindful of the impact on other places. To some extent there will
be a local element and that must have an effect on other areas.
It does not have to be too big an impact as I say seasonality
is the primary changer. Bad working conditions in banana plantations
is an issue that must be tackled , but it vcan be a healthy
source of lowC food. Lets not cut that off , just because its not local.
Balancing the ? , factory farming produces much less CO2 , but then
it also uses antibiotics , terrible animal ethics . Organic farming
uses much more land. Mor ewater and more CO2 produced, otherwise if
you want to eat meat. ?
There is no right answer , you cant tell someone where their
priorities should lie . A lot of people going vegetarian or vegan
, do so for ethical reasons and others for environmental reasons.
Its true, if you mass produce , especially something like chicken for
factory farming or for eggs. Or cattle in horrible indoor conditions,
that is unethical and low animal welfare. But the CO2 is lower,
so where do your priorities lie. If you want a lowC diet and want to eat meat
then it would be better to go down the unethical route. The if at the
end of your question, we can eat less meat. Everything in moderation thing,
eat meat less frequently then you could say you will eat free-range meat
, at a sustainable level, if you consume at sufficiently low quantities.
I give talks on energy and general consump[tion and I always have to say
to people, reduce our CF and we'll be back into the stone-age.
We want to reduce it to the level that is sustainable
, stil 5 to 7 tons of CO2 per person, but its not 15 tons.
Get your overal CF down to that level , could be via lower
meat consumption that is ethically produced.
Theres a technology that may well be coming in soon, where on
brownfield sites around cities, they'll be putting converted
shipping containers and hydroponics inside to grow salad crops.
I can't fathom whether that is advantageous in CO2 terms
or the present large-scale growing and large transport costs?
The scientific answer is you have to do a life-cycle assesment
of this option compared to the current and see which comes out
better. Its comparing apples and oranges. There is this argument of a
move to locally produced food and in theory it can be sustainable.
Lots of examples around the world of urban gardening or urban
farms . The community has risen up , we will not be dependent
on food coming in from other places, unknown inclusions, unknown
effects . Help to produce it, pick it when you want. I'm synical
myself that they can rack up to feeding anywhere near
65 million in the UK, potentially to 70 plus in a decade or so.
A dreadful cycle, we must feed this lot , more children, more
food required, where is the limit?. If you are not prepared
to declare a boundary then there is an infinite line needing food?
Always touchy, what can you do about population growth.
It would be a really good way to overall reduce our CF, and impact on
environment. There is birth control and other ways of not forcing
people not to have children. For food there is easily enough space to
grow it, 1/3 is wasted, then there is over-eating.
We eat too much food in the Uk and globally . 800 million
people are clinically obese, of BMI of above 25/30 you are clinically
obese, above 40 and you are morbidly obese. But 2.2 billion
are classed as overweight, whether based on BMI , I don't know.
The stats that global organisations are using now.
1 in 3 adults, many children as well . This includes the people
who don't get enough food. Perhaps partly due to lifestyles
, not enough exercise, but mainly due to excess food intake.
Some people work so many hours, there is stress , and no time to
make soups out of chicken carcaces. We used to do it , but have we
the time these days?
And the convenience lifestyle has led to quick food , which is oftn
highly procesed .
In war most of the men were at war, women in the factories, on a massive scale.
People did not have time then. The government had control of the
food supply . These days we can consume what w ewant, when we want
and so we do.
So is food too cheap?
This was raised by Molly Kato? the MEP green party member.
Food is too cheap , you could say. But another tricky issue. About
1million people dependent on foodbanks in the UK. Bu tthat means the other
64 out of 65 million , have a high CF , because they are affluent enough
to be able to do so. Then all the knock-on effects, the health
service along with lack of exercise. Built around consumeism
a lot of issues.
I went to a do at Reading and there was loads of different insects to try,
but when I went on line , very small packets available, for ten pounds or so,
what is the CF there?
Eating insects. A speaker here on that Jenny Josephs. The CF is very low,
nutritious for the protein content. It has the potential to be
sustainable. Also with some energy solutions, we're not quite there yet,
bu tthe potential is really good. They can be stacked so little land use.
Hardly any water .
So why are they so expensive?
Like anything early on in the market staging. Not selling enough to be
able to produce at a cheap rate. We can talk about artificial meat,
meat substitutes is another one, insects is one option.
This is the impossible burger. Its new a meat free burger. The difference with
quorn burger , lowC but unpleasant taste, so not bought.
You don't buy such , because its a highC burger , you want something
tastey. Thats what will dominate people's purchases when it comes to foood.
The impossible burger launched in US , last year. It is plant based.
After 5 years of research , they've got haeme, as in haemoglobin , the
thing that gives it meaty texture, now harvestable from plants.
They even sizzle when cooked, the correct texture, burger-lovers,
meat lovers are tasting them and giving positive reviews.
This kind of thing can be the future. 1/8 the greenhouse gases of
a normal burger, hardly any water or land requred.
Is it heavily patented?
I suspect it is. They're quite open about the ingredients,
potatoe protein, coconut. A small start-up company in San Fransisco.
In regular burger joints its about the same price as meat ones.
Not mass-produced yet, and there are competitors. Meat free
pasties etc are becoming more common in UK shops and becoming
more tasty, so we're getting there.
In Oz there is a chain of takeway shops called Lord of the Fries.
They diversified from chips to burgers, but they never said it was all
mock meat. They've now admitted its been vegan , the whole
time thet've been serving it. Its of couse now a selling point
and thery're expanding exponentially. ?
A nice point. Jenny Josephs who gavea talk here . I was with her
Saturday where we both gave a talk at a festival. I did the general
stuff and she focused on insects. She did taste tests with meatballs
, sausage rolls, 50% pork , 50% mealworm or whatever, crickets etc.
People usually cant tell the difference between full meat and
mixed with insects, or prefer the insect ones as more texture
or just nicer. So don't knock it until you've tried it.
For a meat eater , more than 100gm of meat a day on average,
your CF is so much, for a vegan its about 40% of that.
More and more people are eating less meat these days, but still
a vast majority are committed meat eaters. We think only
3% of people are vegetarian , less than 1% are vegan.
Fish is a very lowC source of protein so the pescatarians
are only saving another 2.5% by going totally vegan, cutting out the fish.
You can save 12% by staying meat-eater but switching from
beef and lamb , the methane producers, to pork and chicken, the same amount.
On fish, the actual CO2 evaluation. They are wild caught are different
to farmed fish, with added nutrients. Is there full account made?
The data is based on real assesments that have happened.
We won't know the exact CF of every single fish, depends where its caught
etc. But generally wild-caught fish have very lowCF because
they feed themselves , compared to chickens say , where they need fields and
fields of soya and othe rgrains , to just feed the chickens.
Sending a boat out to ctch a load of fish, its not a huge amount of
diesel. There are fish that should be taken from farmed sources, halibut
is one species. Halibut is a popular fish, high demand. It takes a long time to
mature, 8 to 10 years. We've stopped intentionally fishing them
wild now , quite a lot as by-catch though. Good in many ways, it gives the
wild halibut the chance to recover. Farmed fish can be done at a
sustainable level, possible to factor in ethical measures, whether happen
or not is enother debate.
Fish farmed or in the wild still produce the same amount of faecal matter ?
They are cold, so their metabolism is much more efficient. Cows are chucking away lots of their energy , just to stay warm. It is an inefficient
process to get protein for us, using anmals that use a lot of the energy
just to keep themselves warm.
Would it be advantageous to consume wild game, as compared to ? game
Possibilly, its never cut and dry, it depends on the specific situation.
My stock answer for this, is do it at a low enough level, then its sustainable.
If sustainable in the ecosytem ,those wild game have enough food
and all part of their normal habitat , then fine. But more often than
not, the population of humans , going up exponentially and dominating the
Earth, in the last 100 years, it tends not to be sustainable. So we have farmed
or mass produced alternatives to meet demand.
At the moment we are over-run with deer in the countryside.
People are talking about reintroducing lynx to try to keep the deer
population down? so a good argument saying eat more venson?
Wolves in Scotland . Same with kangaroos in Oz.
Cutting down forests for soya production , is that the main driver or
cutting down for the sale of timber being the main driver?
Mostly the driving is for agriculture. For some tropical areas its for
logging , for the timber as well. But mor eoften its so the land can be
quickly cleared, to grow food as that is where the money is.
Eating organic. I beleive it is preferable as artificial fertilisers
ar ecut out, soil is preserved. There is a question about how much you
can get from the land. Permaculture with mixed crops , get more from
the land used in intensive agriculture. Could you give more clarity?
The film Tomorrow, a recent film. Its basically saying our current
system is broken. Not susstainable , we're having impacts at all
levels we need to reset society and think locally again.
Not just the food system , educataion, the economy what we
spend goes out to big multinationals rather than local.
Permacultur eis one aspect of that. A certain amout of land can be so
much more productive, but its labour intensive.
Again it comes back to busy lifestyle, it will come back to just 1%
of people who care enough , to do permaculture and have a minuiscule CF.
In my mind it will only be a small percentage, not the majority.
Permaculture is a nice idea, do it where we can.
With organics , yes an absence of fertilisers is a good point.
CO2 going into the atmosphere from all our energy and transport use.
Methane the cows are producing , that the paddi fields are producing,
the landfill is producing . Its 25 to 40 times higher than CO2 .
The nitrous oxide from fertilisers is 300 times more than CO2.
I was told fertilisers were the biggest contributor within food production?
Not true , its the biggest in terms of 1kg of fertiliser used ,
mor eglobal warming potential than 1Kg of methane emitted, true.
ut overall there is a lot mor emethane emitted than nitrous oxide.
Artificial fertilisers are bad in that sense but on the other
hand allows food to be grown quicker , or bigger or mass produced.
A second thing, not fully understood at the moment , is the soil.
Soil degradation, mass agriculture intensively, is damaging the
soil . Again ok in the short term , but like deforestation, short term we can
have fewer trees and we'll survive. It means our total ecological
footprint on the Earth is way beyond 1 planet earth.
We know hte oceans absorb a lot of the CO2 trhat would otherwise
cause global warming. The rest goes into the atmosphere and that is
driving GW. The third big C sink of GHG emmissions is the soil.
That bit is not well understood yet and intensive agriculture,
degrading the soil , is reducing its ability to store the C.
Potentially a big crunch point that will lead to runaway climate
No mention of GMOs. For example producing a better shelf life
and less wastage. Or produce rice that requires less water etc. ?
Again GM products are poorly understood. A bad time in the press.
Also a failure of science communication, badly comunicated to the
public and so generally the feeling is that GMOs are bad.
What might happen , and so a fear around it. But
actually it is scientific progress, solving real-world issues .
So developing a more resistant strain of a grain or veg , can
potentially feed starving people and do it where there may be drought
or flood tendency, and not loosing a whole crop.
A great potential for GM. There will be legitimate counter
arguments and exceptions.
As consumers we need to accept more responsibility, for what we
consume, more conscious of environmental impact, but there is also
a role for marketing to be controlled. The BOGOF business
and continual encouragement to buy more all the time, and then
throw it out. Can you see legislation to stop some of this
over-marketing of things? The wrong shape cucumbers thrown out
on the farm, even back in the 1960s?
There isa role for governments certainly. Brexit will mean we'll
lose a lot of the regulations, the EU currently has.
So implications there on environment and bio-diversity.
There is also a role for culture. There isa slight shift in culture.
Competing supermarkets are attuned to this , one supermarket is
marketting funny shaped cucumber and bananas and making that
a marketing thing now. Someothers are dealing with waste, Tesco
and Sainsbury, there. In France the government has told supermarkets
they are no longer allowed to waste food, they have to do something about it.
Legislating to make that happen there. I believe personal
actions can make a bigger difference overall.
The environmental argument tends not to be the main driver
for most people, hence my interest in the impossible burger.
Its usually taste that is the bigger factor with most people.
More than ethics, more than environment, nail that one.
Adopt some of my ABC measures of LowC eating , you can
potentially save something like 500 to 1000 GBP a year as a family.
Avoid the avoidable food waste, not have no food waste as not
realistic. Buying in-season food and switching to lowC foods more.
not extreme veganism , just beef to chicken change, modrate
amounts etc. A recent study showed that if we reduced our meat
consumption not to vegetarian or to vegan , just to the level the WHO
is saying is healthy for us. That would cut our CF by 1/3.
Go vegetarian it would be 63% off your food CF and going to
vegan is just another 7% to 70%.
When wil lwe see the CF printed on packaging?
Its unrealistic unfortunately. Some people have done
red amber,green markings but that is more to do with health.
Consumers want to know if its tasty, then whether it s
healthy or not for you, fat/protein/carbo breakdowns.
Peartly not enough appetite for it . Also too difficult as not only
depending on exactly what piece of fruit it is, whether
it was in-season when picked, the time it was shipped ,
refrigerated , th eboat route.
How many smokers wanted to see death warnings on their fag packs?
Ultimately it is legislation but I doubt there is enough political will
to make it happen. It becomes important to think of the health
arguments. THere is a good correlation , cheaper foods
generally are lower C foods. Also a reasonable correlation
between the health of food and CF of food. If you wan tto move to
a lowC diet , that cuts out a lot of meat, almost certain to be
cheaper , but also healthier for you.
The carcinogenic properties of red meat and processed meat,
and other comparisons can be made.
What is hte CF of beer?
Beer's a funny one, and also is it vegetarian. They often use
fish guts/ininglass to fine the beer. There is an alternative
used by Budweisser etc. The CF of beer is not easy to
answer . You could do a C analysis of a particular beer.
It has grains in it . For 1Kg of beef the CO2 equivalent is about 18Kg,
for cheese about 12, go to chicken or pork another third off,
about 6. Go to rice its about 4Kg. Wheat comes in at about 1.3Kg.
It will be higher than average fruit or veg in-season, but much
lower than meat or dairy products.
Fruit based alcohol , might be lower than beer.
Banana wine, the ultimate solution.
Could there be a cultural movement to wards beef and lamb
being considered a treat rathe rthan routine, as a way of moving
people towards less meat?
Some chefs have hooked onto the concept of meat-free monday.
I don't think it goes far enough but one good thing about it
is it gets people realising they'te not dependent on meat.
Its become normalised to have meat, if you have a meal
it must have meat. One of my main take-away concepts I emphasise
is move away from beef. A beefburger is 3 times CF of a chicken-
burger. Move away from the methane-producing ruminents of beef and lamb, and go
to chicken and pork.
An average cow doing its thing in a field , eating grass, regurgitating it ,
generated something like 300 Litres of methane a day. So much the same
asthe CF of a car use in one day , just from a cow being alive in a
field for a day. Lamb raising tends to be on uplands and poor grazing land
not useable by anything else.
If we go back to the sustainable level and have lamb once a month,
as a treat, then maybe that scenic upland life is the reality. But if we have it in the
quantities that we currently consume lamb, there is the hidden
reality of tens of thousands of sheds for raising sheep. Certainly so
for beef and pork.
Is there anything you could use the methane for, if you could harvest it?
Its not feasible. Its one of those out-there ideas. When we consider landfill
and waste management we do use the methane now.
Its sealed landfill these days , capturing the methane and it generates
electricity, relatively small quantities ,but mainly its not going
into the atmosphere. Change what you feed cattle can
bring a reduxtion of methane down about 50%.
A specific mix of plant foods will produce a specific micro-flora
in the gut , the metabolic pathway changes and less methane produced.
A common misconception is cows farting out the methane, but a higher
percentage is belched out. A bag over the rear end maybe possible but
the more necessary bag over the eating and breathing end is not possible.
Changing the diet of animals, you have to again consider the CF
of that alternative low-methane food.
A chef friend of mine , his dream is to produce vegetarian meals that
people would find captivating to look at and be tasty.?
Another way is via rice mechanisms. Say at Glastonbury there are loads
of vegetarian and vegan options , but what I do like
is where the vegie burger or curry is a bit cheaper. That often
does not translate down because of mass-production issues.
Composting query. Garden compost heap it breaks down , releasing
gases to the atmospher. Compare to going to landfill and anaerobic
We have loads of people working on composting and also anaerobic
digestion as a future solution for waste management.
I don't really like it as a solution in this context as it basically
legitimises food waste. Whereas high C , human grade food ,
should be eaten and not wasted.
Monday 14 August 2017: Dr Alex Dickinson, Soton Uni -
Engineering Replacement Limbs - a Global Challenge
19 people, 1.5 hours
Injured vetarans and services people have raised the profile of the
people without 4 limbs. This interest has allowed us to generate funding
for research into lower limb prosthetics(P).
But they don't represent the majority of cases, people who have lost
limbs through trauma or infection . Such as Johny Peacock represent only about 20% of the population who've lost limbs. Diabetes and vascular disease
account for 80% in this country. So we try to learn as much as we can
from the highly functional amputees, to develop technplogies to
help everybody. The clinical need , is from someone who has
just woken up from lower limb amputation to someone who
is fully rehabilitated. Still in 2017 , the majority of ways that a P limb
is designed , is through a process of plaster casting.
So a negative cast from the remaining limb, turned into a positive mould.
Then a series of rectifications to the shape. Changing in a very strategic way
to get a target load transfer. Below the knee amputation, trans tibial
and posterior view. The prosthetist (Pt) has a few target areas , where they're
trying to load the limb. Feel around one of your kneecaps , the bony kneecap
and then a bit farther down another bony lump, the tibial tuberosity,
where your quad muscles from the front of your leg join
onto your shin. Between those 2 boney lumps , there is a soft
spongey bit, this is the patella tendon where your kneecap
attaches to your tibia. That is a very low-tolerant area
, you can press on that all you like. The pt makes a change of shape
so you can bear load there. They want to avoid bearing load on the
resitual tip of the stump, because that is very sensitive.
A GRP tibia with the load bearing ends are relatively large,
but do amputation surgery , cutting through the middle, the
cross-sectional area is much reduced. So you would expect the
pressure to go up . Also if you feel on the inside of your arm ,
its similar to the skin oon the back of your calf, its very soft and delicate
in comparison to the skin on the palm of your hand or sole of
your foot. The tissue is not designed to take the pressur eof walking thousands of
steps a day. So requires an experienced Pt to do this rectification
process . Take the positive mould and with a file or surform
, remove material from under the kneecap , and then perhapsa tub
of plaster of Paris and build-up material o nth etip of the cup.
Once she is happy witht he shape , she'll try a trial socket.
Polypropolene , still in 2017, a big sheet of it, in a frame, placed in
an oven at 200 degrees until the centre dips a couple of inches.
|Place it over the mould, suck out the air via vacuum, so vacuum-forming
a trial socket. So you can see the indentation that will go under the kneecap.
A square cut-out at the back , so the subjec tcan flex their knee.
Then an ireative process, by which the Pt, gives it to the person its
designed for and see how happy they are with it. Much like snowboard
boots, with a heat gun can make modifications to regions that are too
tight or are not pressing hard enough. The problem is, a lot of people
who have lower limb amputation , from vascular disease, they loose
their sensitivity i n the soft tissues, so they don't know they are
pressing too hard. So we make it transparent , so as normal with pressing
anywhere on human skin it goes white. But people with vascular
disease often loose that response aswell. The result is that in the first year
after amputation the average is returning to your Pt , 9 times.
That is data from across Europe. In the Uk perhaps not so many
as difficulty in getting the appointment. The rehabilitation success-rate
via this sort of process is about 50 to 60%. People with this setup,
have a dilemma , do I tell my Pt there is a problem or put up
with it ,bearing in mind I'd be without my leg during the 7 weeks
of modifications. It seems wrong that in 2017 people are having to
make that kind of decision.
In 2012 I thought, as a mechanical engineer , how could I help
ways around this. I was in the position , many find themselves at uni,
where I have to justify myself into staying there instead of a post-doc
role contract of 18 months if you're lucky. My prof who took me thru
the PhD was an expert in artificial joints . So what other area might
the techniques I'd developed , be useful. What tools do I have that may
be of use. The goto quote , for mechanics, is from Lord Kelvin.
"To measure is to know, and if you can't measure it,
you can't improve it". So how much of what Pts do, is actually measurements
of what they do. Extra data they could take out of the processes they are
using, so at least they have a record of it. What I thought was a brilliant idea,
I soon found others had thought of this also. So CAD/CAM techniques
in Ps. We no longer draw stuff on paper any more . CAM is a collection
of technologies, CNC a lot Computer Numeric Control conventional
machining methods controlled by computer. 3D printing/ additive
manufacturing is the latest. Pts started to develop this in 1980s
and until 2000 until use in any number. The Pt will use a scanner
to capture the shape of a residual limb , digitizing it, create a computer
model , then they can progress the rectification process in a CAD
environment. So the under-knee indentation they can create, and at the
front of the tibia they can remove material away from the limb,
so not pressing on the shin bone. Also the fibula head on the outside
, a nice structure that can be presses avoiding a nerve that passes over the
top of there. They can now make more accurate and quantitive changes to
the limb shape. Then CAM via milling , start with a large polyurethane
block , placed on a turntable and a multi-axix robotic arm with
rotating milling bit, carving out, in theiry, exactly the same shape
as in the design. These robots tend to be in their own room so the
dust generated is not inhaled by the operator. The robot does a rough
machining operation , including a sneeze function , to clear dust.
So I looke d at how we and th Pt could do more with this.
They would use these new processes but carry them out in the same
way as plaster-casting. They'll know the regions they are looking at ,
for changes. While they can make quantative changes, they are still
like free-hand sketches on the limb-shape. So we take an
aquisition, a scan, we could bring in 2 computer-shape files ,
represented as meshes , a series of points or vertices, joining the
points into triangles. The 2 colours represent 2 scans of the same
shape . Then we can do imprecise alignment by translation and
rotation , by hand. Then we can do a more accurate alignment
by iteration of a process called closest-point matching. This gives an
automated process by which we can align the shapes. Being automated,
it is less likely to be subjected to human error, ie I don't have to
be a fully trained technician to use this. You can see different regions with
mor emismatch . If exactly the same shapes, al you'd see was
noise, no mixture. Thena final process called registration where we
map one shape onto the other, allowing a point to point comp[arison
between the 2 shapes, w ecalculate the Euclidean error.
Pythagoras in 3D, RMS in 3D. We need to present the data in an
interesting or at least accessible way. We produce a colour map of the
shape deviation , just 1 colour is slightly higher deviation.
We only have high errors around the interfaces, the place where there
is some human input, so the case for automation.
We used this with a project from archaeologists, comparing different
teeth. A P socket is more or less the same shape as a tooth.
How might the P community be interested in this research.
Were we using the right kit. Same technoique using state-of-the-art
scanner , relatively few NHS clinics have been convinced to use
so far. Its a structured laser scanner , about 30,000 GBP .
Inevitibly a barrier to it being taken up. We are then using something
very technological in clinics compared to something that was very
tangible , manual and experienced based procesing. So we need to
introduce such changes in a sensitive way , so it does not come across
that we are trying to replace the Pt experience and skill. It has to
be a tool to allow application . Such scanners are usually deployed
on automated car production lines , scanning pressed panels for example,
so extremely accurate. So we though we'd try characterising how
accurate. So we 3D printed a test piece, so we had a good idea
of its accuracy, at least we know what shape we sent to the 3D printer.
So colour scale-bar 0 to 1mm , 95% of the surface comes within 0.16mm
, comfortably more accurate than 1mm.
So an Amazon purchase for a 300 GBP scanner, but is it good enough.
Extended colour map now 0 to 3mm and the accuracy is about 1.5mm .
We can see a systematic error, along the length , which is interesting.
We can correct for such systematic errors , but its still imp[ortant to
try and characterize what the error is. At that stage we did not know what
error is important. Prod some soft tissue on your hand , it takes very little
force to move it 1mm, so maybe 1.5mm error is good enough.
Secondly we thought it might help the centres that already
have this kind of technology, to develop best practise in their
limb fabrication. S oafter they've designed the limb , does what comes out
of the fancy robot, actually match the original shape. We can take the
shape we sent to the cutter, we can subract the socket shape that came off the
mould and use the same colour map . We can then see how errors
manifest across the surface, so this is relatively reassuring.
In the concave regions we have a larger surface error, gives some
confidence as the shape is created under vacuum , release the vac and
some of the material will spring back. Around the periphery a "blue"
negative colour, some interference, causing the shape to spring back.
A sanity check - where we put some real physical data into our
computer programme. Also can we try to inform socket design .
instead of telling a Pt how to do it, we can take in large amounts of
data from previously designed socketys, which have achieved a successful
outcome and give them info on what is a good first-guess socket
for an individual.
So an example showing blue , where pressed in under the kneecap
and the red regions where the socket is larger than the limb , where
material is added to bear load. On a population scale we put in a
lot of stats, work just progressed into a recent paper.
What is the effect of the design on the soft tissues. These soft tissues
have to change the job they're doing, between healthy pre-amputated state
to when having to bear full body weight, on the nice soft skin that
was on the back of your calf, not used to bearing any load.
How to change the tissue for this new job, to become more durable and
tough. Like learning to play guitar and callouses on your finger-tips.
With that , if painful, you can leave the guitar for a few days and then
pick up again , but not really an option here. Any pus ein the
rehabilitation process affects other aspects.
So if there is different prpcesses adopted by Pts , can we put some
evidence-base behind the design process.
3 design processes a Pt might consider
The Total Bearing Socket TSB, very little change between socket
The Patella Tendon Bearing, particularly relying on the press
fit withthe bearing surface under the knee, we make focal changes,
technically more of a demanding socket to create.
Not used so much these days KBM socket from the 1990s , a German
name. Some marked press-fit regions above the knee, grips the limb
side to side, a much more bulbous shape around the residual limb.
So we can describe these shapes by looking at the outsides of the limb
and the design of socket. We can use imaging to try and understand
what is happening insode the limb, how the socket is being
reconfigured by the socket design. Using MRI scan slices , showing
ups contrastining between different soft tissues. The bones, residual tibia ,
femur and knee cap, tendon , the layer of skin and some of the
muscles , some calf muscles wrapped around the end of the limb
and sutured onto the front and the fat-pad on the tip of the limb.
So well established amputee where the muscle starts to atrophy
, as not used in an established way, and transforms into fat-pad.
We can see the marks of the more marked rectifications in a couple
of cases. The KBM socket has manipulated the soft
tissues to move upwards and backwards.
Then the triangular shape of the PTB socket , pressing either side of the
shin so we dont load on the shin. There is very little change of shape
to the vacuum formed.
So taking measurements to see what those changes of shape actually
cause. Unlike designing a piece of Aluminium airframe, that has been
heat-treated the right way , we can say wityh a great deal of confidence
when it would fail. A lot of mechanical engineering is structural and stress
analysis . We know hte stresses, compare to the material strength
and know if its strong enough. Soft tissue material vary dramatically.
Vary person to person . Just because something does not actually fail,
doesn't mean it will be comfortable. Some people have a diminsihed
sense of what is comfortable, and these people may be the ones we
have most concern about, in having soft tissue problems.
So we also take a series of biophysical measurements, to understand the
effects on the residual limb in compression and shear, in terms of changing
tissue oxygenation for example. And inhibiting the lymphatic flow,
the way waste products are removed from more distant tissues away from the
body centre. We just today submitted our ethics application
, as even just self-experimentation , it need ethics approval.
So as an engineer , who else migth be interested in such techniques.
This is a global problem . There are predictions that by 2035 there will
be a half billion people with diabetes worldwide, disproportionately
affectring the developing world . 100 million people worldwide need some
sort of Pt device , and 90% of those don't have access to the services
providing them. The access problems include lack of funding
and infrastructure and also personel training. Finding certified
Pts to provide these limbs is a real challenge.
We went to Campodia, somewhere infrastructures that may be
starting to be in place, and be at least receptive to what we have in mind.
Could our crazy ideas be useful. Between 1975 and 1979
about 1/5 of the population diesd in genocide . The polpot regime
determined that the population should return to their agricultural
origins , closing down all school, universities and hospitals/.
The borders with Viet Nam and Thailand were covered with landmines , to
stop the population leaving. Not just the people trying to cross
the borders but also the soldiers patrolling the borders, ended up with
lower limb amputations. So homebrewed peg-legs , very basic,
but people wearing them every day. Even the soldiers , the majority
prior to Polpot, had been agricultural workers. Once they wer einjured
they had ro return to agriculture, trying to work with 1 limb or even both limbs
missing. So not just walking the streets but working in padi-fields
for 12-14 hours a day. In 1990s the Cambodia trust was set up
, providing Pt limbs to anyone in hte country free of charge.
A Pt broken at the angle, held together by tape, turned up
a tthe clinic , and repaired and he returned to the very physical work.
They are all produced by a Red Cross unit in the capital Pnom Pen.
Standardised limbs , example passed around. So someone is injured, they
have medical treatment, they go home to a different part of the
country to convalesce with family . So you take your Pt with you
and can then walk into any clinic and have components replaced,
there and then. All the brown polypropelene components
of the limb are completely recycled. The condition that allows you to
take away a new limb with you , is you leave your previous one withthem.
A large box at the rear of the factory with a lawn-mower engine on the
side , and a blade inside. It turns the plastic back into granule size pieces
that can go straight back into the injection moulders, for new ones.
Nearby is the artificial leg and rubber processing company, 12 grandchildren
and grandfather produce 500 Pt feet per week, the foot on the
limb passed around. These Pt feet have proven to be the strongest available
for use in a rugged environment. They start with various grades of
synthetic rubber , in shhet form. Roll them on a table and produce a
pre-form , then an injection moulded nylon heel , and the rest from sheet
black rubber . Then squares of more flesh coloured rubber , around the
outside, placed in moulds and placed in an oven, then tidy up the edges.
This process runs continuously . 500 a week produced by just 1 family.
The first challenge is funding. One of thesePt limbs does not do the
job for the rest of your life. In the UK its estimated at 1000GBP
per year for a single limb repair and replacement, for the
rest of your life. If you have govt or national funding , then economics come in.
For a given pot of money its better to fund road safety measures, as now a lot
of the minefields in Cambodia have been cleared, the main way people
ar einjured from road accidents. Road use is increasing dramatically
and exceeds the infrastructure in place. Peole doing agricultural
work , the money they earn today, is spent on food for tomorrow.
They can't simply take 2 or 3 days off work , to go for treatment
at one of the 11 clinics across the country. There are many there who are
completely unaware that Pts are available and schemes in place.
Even medical doctors can be unaware of the services available.
There is a clear difference between what is considered medical
and what is considered disability. So can some of our developed
techniques advance the access. So would the 300 GBP scanners be
sufficient to characterise the shape of the residual limb. So why
are we talking about this extra cost when a sack of plaster
can be bought for next to nothing. The Arts and Humanities Council put a
nice statement together on this , which summarises a lot of past
experience. Many scientific and technical interventions
continue to fail, due to a lack of understanding of the social ,
cultural and historical contexts and their likely reception
be th e people they are intended to benefit. Some notorious
examples of this- The National Formula milk scandals from the 50s/60s,
where people sent formula milk to Africa. Then people were unable to produce their
own milk , to nurse children. When the formula project ran
out , there wa s a famine. More recently some of the ways the
Ebola outbreak was managed, without consideration of some of
the cultural , social and traditional aspects that were very important .
So we have to make sure, that just because we have a bit of tech that
works in the UK, and if we find a funding for other parts of the
world; it doesn't do more harm than good.
A lower and middle income issue , in general. We try to take an inter-
disciplinary approach to understand what the requirements are ,
in other countries, without making assumptions involving what
we have access to. Also sustainable business implimentation.
Tools and spare parts have to be considered. We have the mechanical
engineer, the physiotherapist for the scanning, a health-care
psychologist a qualitive researcher. I was trained as to being
purely quantitive . Its a process of understanding what people
really need, as a mechanical engineer , I never saw that aspect.
Also an entrerprise fellow , in the faculty of health sciences,
who understands business modelling techniques , how a business
case can be built for this kind of tech.
We are in Soton, how do we test any ideas with the people who
really matter. So we work with the International Society
of Prosthetics and Orthotics, and also th eCambodian School
of Prosthetics and Orthotics. The first fully certified by ISPO
asa training school in SE Asia.
(Orthotic are an addition to assist the body like hearing-aids Orthopedics are
replacing missing parts of a body)
They now train the whole sub-continent , who end up in Africa ,
the Pacific Islands and across S America. These people have the
influence to implement ideas, we eventially came up with . are
actually workable. We've been able to answer questions that
we could not ask in the UK.
The casting process, the most important element is the Pt
thumbs. He identifies the regions around the knee, around the
patella, the tendons. When they are roughly confident about the
shape , they press either side of the patella tendon with
their thumbs. Blinking between the 2 images , you can see the
shadow created by the thumbs. They are already rectifying
the socket , when they are taking the original cast
when the plaster is still wet. When they take the cast off
and lokk inside , the residual limb is covered in
cling-film , they draw around the regions of interest with a felt-tip
pen , which transfers to the inside of the socket.
A human very much involved in this process , so whenever
we have a human, we probably have some variability.
A question answered in Cambodia, not available in the UK,
just how repeatable is the casting process.
So 2 clinicians taking pairs of casts of a small group of volunteers.
So pairs of nominally identical casts . We feed them into our
shape comparison system. Repeat casts of the same person ,
done one immediately after the other . We can start to see the 2
thumb-prints , rendered blue in the images. Then we can see the red
zone where material is added on the tip of the stump.
Also the red stripe down the front where we've added material
, pressing on the sharp edge of the shin , the bit that hurts when
banged against a table. So does someone get the same result, one time after the
othr. So answering the fundamental question, how accurate do the
scanners have to be. How much do we need to spend on them.
So this is being used now in a couple of projects in africa .
Its important that the Pts tell us the reliability of the tools they've
been given . These results are hot off the press.
So is there scope for these technologies in Cambodia.
In the small local market selling chickens and edible tarantulas,
a booth selling second-hand mobile phones. So you can buy a
reconditioned Iphone, for 1/4 the cost in West Quay.
Their technological development bypassed the dial-up
period we went through. They've gone straigh tto 4G connection,
they've got beeter 4G than I can get in my house
200m off a main road in the UK. So access to data , via
networks is far better . So we are trying to develop appropriate
data technologies around Pt and orthotic processes.
The interesting word is appropriate . The limb I passed around is
what I'd call appropriate tech. Its not the most advanced Pt limb
in the world , but it is appropriate to the communities in Cambodia.
So scanning systems that collect the right amount of info ,
ways of presenting it in the right way, feeding info back to the
users . You can often now connect the 300 GBP scanners to your Iphone
, certainly to an Ipad, transmit it back to the Pt clinic.
They can transmit back to the user on their Iphone, the info
for care of the residual limb tissues, how frequently they
need cleaning, and the socket. How often is too often to be cleaning.
Reminders about the rehabilitation process, via audio and
video demos. Tell them how to repeir their own Pt limb, so they
don't have to take 3 days off and return to the clinic.
The charity does reimburse people, loosing work , to have to
return to clinics. Techniques like this might prevent them having to
return to a clinic 1 time in 3, an enormous improvement.
We're not just looking at the technologies , but also ethnography ,
human factors in what people need and need to understand.
Courtesy of EPSRC , 1.5 billion nationwide towards
global challenges research funding , which includes the work explained
here. We've applied for some mor efunding, so diid 140 other
groups and they expect to fund 6 to 8 projects.
Acknowledgements to colleagues and students, collegues at
the Fraunhoffer Institute , Germany who wer e part of the
MRI study , part of a much bigger study . The clinicians
and participants in Cambodia .
If someone has had an amputation , do they ever add a
prosthetic that protrudes out of the body?
Dental implants is an area where thry have the same challenge.
So we use the the same process called osteo-integration , directly
to bone, used for knee replacements for a long time.
But you have something that goes through the skin, a wonderful
environment to cultivate bacteria and other things.
The dental implanters were the first area to try that. A 19%
infection rate, not just superficial skin infections but
nasty deep infections. If we had a 19% infection rate we'd
be in great trouble.
I thought it would be a good way of taking a lot of the load?
Yes that and the feedback. A lot of the challenge in the rehabilitation
process is the feedback , back from a prosthetic limb.
We have limb position awareness without having to see them.
Being able to sense where or where not a prosthetic limb is,
is a problem.
Connect directly to the skeleton and this feedback is very good.
Your skeleton adapts to load change , as well as the muscles.
Why the astronauts on the ISS lose some percentage of bone
and muscle. If you get an unexpected load, say fall over sideways,
bone is not adapted for such loads and get a fracture in the bone.
I met a boxer with a pair of osteo-integrated limbs and he carries on
doing boxing training
Does the phantom limb integrate with the prosthetic limb
The osteo-integrated process has allowed that. I was at a 2013
conference where they presented the first surgery , upper limb
prosthesis control. We can control a hand movement by
EMG sensors electrmyography, electrodes over the muscles.
You retrain the muscle group , that otherwise are no use becaus eof
the amputation . Stick the electrodes on the outside of the body
and use for controlling opening and closing the prosthetic hand.
If you go outside in the cold or the humidity rises the sensitivity
reduces and tendency to loose the control. So sensors are placed
inside the body. Still a relatively small number of people
I previously thought the matching process between the stump
and the prosthetic would be arranging so the pressures were
evenly distributed over the interface, but I gather that is not the
case. Not necessarily maximise the pressure , but increase in some areas and
decrease in other areas?
There are competing scjhools of thought . There is a further method.
The scanning and plaster casting techniques, the big diffwerence is
you are capturing the shape of the limb when its not under any load.
So things will change as soon as it bears weight. So there are some
clever, relatively simple tools . You can vacuum cast or sand cast the shape
while bearing the load of a dustbin of sand .
Is there anything coming from the area of animatronics , remotely
moving jaws and eyes etc for filmic purposes , but brought in to this.
Say someone is going through digging movements, then you can remotely
adapt , via pneumatic systems , when in the right place then lock it
in position. Then go through the casting process?
People are looking at adaptive sockets with sensors that can
change the stiffness, depending on the amount of load.
That is in a final socket, they are things the industry is working on.
Concerning the accuracies of the different technologies and you
get different results , if you have a subject who walks straight
in from the coldcompared to someone who has been sitting in the waiting room
for 15 minutes.
Is that a repeatable change, different people going throught he
same change of environment would have the same reaction?
Too many variables. From an experienced prosthetist, concerning a
subject with 3 new limbs produced, they compensated for limb loss
by adding socks t othe gap. So prosthetists talk in terms of
number of socks. With each of the 3 limbs , they needed 4 socks to
manage the pressure. So what was going on. They had diabetes and were on
diuretic meds. He lived a 3 mile cr journey from the centre, so they
did not take the diuretic before getting into the car, so they were larger.
So mechatronic control , to get the socket to adapt to the
limb. That is the area for people with very expensive private
healthcare. Thats where a lot of the exciting engineering seems to
happen . You can spend 30,000 on a limb but if the socket is not
Is there a system, not strain-gauges as such , but a mesh of perhaps thousands of very small-resolution strain elements on a flexible membrane , that can form into
the 3D shape. Place that in the interface and remotely monitor with the
subject walking or jumping, sitting or standing-up from sitting or whatever?
This was in a PhD paper only last week , so I'm not allowed to
say too much, but it comes down to how few "strain-gauges" you need for the
result. We as engineers would be comfortable with htat , but not so
a prsotheticist. So how to optimise the amount of data that comes out of such
as that and how you present it to a busy operative.
There are adaptive polymers that change their stiffness, according to the amount of current passed . Or sockets made of 4 or 5 arms , then webbing straps with
tension bands , that controls the bulk stiffness of the socket.
But the sensing inside , and whento change the settings , is the complex bit.
Are these fabrication techniques being used in our local hospitals or are
they just very specialist centres, are the scanning techniques readily available now?
Theya re starting to get some momentum . The techniques were developed
in the 1980s , but only mid 2000s did they start being used in real numbers.
A lot of prostheticists see this as getting a worse result much faster,
so a lot of training and a learning curve. Also a sense of threat, jobs replaced
by computer. So if I know I can get a pretty good result by plaster- casting
, from doing it for 20 years , why would I put a lump of
tech between and achieve a result of unhappy clients for 3 months
until we can sort out new problems. One of the ways we think we can use the
emerging data is to soften this learning curve. Help people to understand
how one process they did, went well and another thing they did , was not
successful. Most of the clinics in the UK are starting to
have one of these scanners. Many send the scans to a fabrication
company. So I'm involved with seeing now accurate the scanners are,
what amount of accuracy is required and what is good enough .
Wouldn't it be better to have the subject on a turntable , and a static
scanner , rather than hand-held, keeping constant distance and reducing the
variables before autostitching the images?
Yes. One of the early scanner versions was a halo with 7 or 8
cameras around it , moved over the limb. These single scanner units have
caught on though. The autostiching is done on the laptop that
powers the scanner, no requirement for greater processing power.
My first PhD student looking into how to get it to work on an NHS laptop.
A lot of the things we were doing would only run on a supercomputer
, greta for us in getting published , but ultimately our work
must result in something clinicians can use.