RESEARCH VOLUNTEERING 9 – MOTION CAPTURE AND ROBOTICS

This was a super-cool adventure in the biomechanics lab at Manchester University, which is located in, uh, the Optometry building.  There was nowhere else for it, ok?

The research is designed to understand the nuances of human movement, to apply the findings to humanoid robots. The aim is to make robots move in a more natural, less clunky way. I’m sure that somewhere along the way there will be some Uncanny Valley-like results, but it’s all a step (ha) on the path to more humanlike robots. On a more serious note, the work has applications in medicine, for rehabilitation and developing prosthetics. Often university research sounds rather arcane and peculiar (Ig Nobel awards, anyone?), but it has real and relevant applications.Before the testing day, I was informed that I needed to be of average fitness as I would be performing walking and jogging movements in a gym for three hours. I do consider myself pretty healthy and active, but I was worried that they were expecting some sort of endurance hero to turn up. Fortunately they weren’t, and it was just repeated brisk walking over short distances.
The Biomechanics Laboratory
The Biomechanics Laboratory

When I turned up, the lab was set up with tracks on the floor and motion capture cameras on the ceiling.  At this point I realised this was going to be pretty futuristic and fun, and I was so glad I’d taken an afternoon off to help with this work. As is the case with all research involving human participants, the session began with the completion of consent forms.  This is to comply with the requirements of the University Ethics Committee, and also gives a chance for questions to be answered, and a little more detail about the work to be revealed to the volunteer.  Unlike any other study I’ve taken part in, this activity was accompanied by coffee and cake.  Researchers, take note!  It was quite a long afternoon, so we also had breaks and chatter throughout the session, to break up the repetition.

Following the initial registration process, I changed into a vest and shorts provided by the lab (this was necessary because my limbs needed to be exposed and I had to have various items of electronics fixed to my body).  I was then weighed and my height was measured.  It seems that I have got heavier (by 1kg) and shorter (by 1cm), which is the worst combination.  Damn you, properly calibrated scales!  This was necessary to calculate my BMI (it was a requirement of the study that participants were of normal weight – BMI 18.5 to 24.5).

Then I had a multitude of sensors fixed about my person.  It took about half an hour to get all of the kit on, and the placing of the devices was meticulous.  There were three different types of sensor used:

EMG (electromyography) sensors, measuring the activity of muscles involved in walking.  I had a number of these placed on my legs and lower back, to identify which muscles are active during which movement activities.

Pressure-sensitive insoles to measure my gait.  I also had to wear shoes provided by the lab, and due to my totally non-ergonomic feet, I required a 7 on my left foot and a 6 on my right.

You can see the marker pen still on my wrists a few hours after the experiment
You can see the marker pen still on my wrists a few hours after the experiment

Reflective motion-capture markers, which were placed all over: my shoulders, elbows, knees, wrists, ankles, hips, chest and toes, plus a snazzy felt hat with markers for my head.  In order for these to be placed correctly, one of the researchers had to feel for the exact part of the joint to place the marker, and draw on me with a felt pen ready to glue the silvery reflective marker balls on to my skin.  they also precisely measured the length of my hands and feet in order to relate the position of some of these markers to the rest of my body – my left hand is 187mm long and my left foot 236mm long.  Not sure what I will ever do with this information, but it’s kinda cool.

In addition to the above, I needed to wear transmitters for the EMGs in a snazzy tool belt around my waist, plus transmitters for the insoles were strapped to my calves.

When all of the gear was on, my height and weight were remeasured, and I had gained a centimetre in height and two kilos in weight (not surprising, given how much of the damn stuff there was).

I then stood in front of the display screen in the middle of the lab, and I could see virtual me moving around in the form of a number of white dots (silly dance obligatory at this point).  The researchers also had two screens in which they could see the pressure maps of my feet and the electrical output of my muscles.  The motion capture data was collected by a number of cameras on the ceiling of the lab, and the pressure and movement signals were transmitted over the wi-fi to the recording equipment.

My first task was to stand on one leg and then switch to the other, for both feet.  This is surprisingly difficult, and I didn’t realise how crap my balance was until this point.  This was necessary for a baseline reading.  Then the movement tasks began.  I had to perform seven different actions, involving walking for a short distance, and only slightly energetic.  The researchers recorded the data output for each of the seven actions, repeated ten times each.

Walking around with all the gear on felt a bit strange at first, but none of it got in the way of my ordinary walking style, which was really important as they wanted to record people’s normal, unimpeded movements.  The type of movements that the researchers are interested in are to do with changes in speed and direction, the type of movements for which we can easily distinguish between the characteristics of man or machine.

The experiment took about three hours to complete; one of the longest studies I’ve taken part in.  I got paid £20 for my participation, which isn’t loads, but given that I got to feel like I was in Avatar for an afternoon, it was definitely worth it.  The team are still looking for more participants, aged 18 – 40 with a BMI between 18.5 and 24.9, to participate in trials starting in September.  Details will soon be published on the University’s Research Volunteering page.

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