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Engineer tails cheetahs for the human body’s secrets


Engineer tails cheetahs for the human body’s secrets

South African engineer builds on robotics research to develop a new model for athletes, doctors and others

Senior science reporter

Every time you walk across the road, lift a cup of tea to your mouth or swat a fly, your body is engaged in thousands of laws of physics without having to think about it.
Those instinctive movements are engineering marvels, and we never really have to know about them or understand them to keep doing what we’re doing.
For athletes, it’s different, however: there is much to be gleaned from the way they move their bodies out in the field because those movements hold every secret about improvement, injury, strain and success.
Now an electrical engineer at the University of Cape Town has transposed his brilliant work in the field of robotics – which had him obsessing over cheetahs’ tails – to the field of sports science. This has led him to create an accessible and affordable way of unlocking the secret of individual athletes’ bodies and how they move.
Let’s rewind to when Dr Amir Patel was a little boy. Even back then, he was spellbound by animals and the way they moved. He was equally as fascinated by robots, and these two passions came together in his work as an engineer and academic.
By studying precisely how a cheetah uses its tail for stability during high acceleration, quick turns and sudden braking, he was able to simulate its sophisticated design for robotics and, more specifically, robots that could help in search-and-rescue missions.
That in itself was a great innovation, but in the true spirit of being a “Renaissance man” – working as a master across disciplines – Patel was able to spin his research off into other directions too along the way, and that is where the human body comes in.
During the journey of studying how the cheetah’s tail works, Patel invented a way of capturing the movement of the human body.
Wanting to know more about how this lightning-fast animal moves, he very quickly realised how little research had been done on it.
He then took a multipronged approach: “First, I built simplified tails for two robots. This showed the effect of a tail on agility by replicating the movement of a cheetah’s tail.”
He then developed mathematical models that showed how tails stabilised movement, and after that, he was invited to an autopsy of a cheetah. It was here that he debunked the myth that a cheetah’s tail makes up 10% of its body weight.
“It is actually extremely light,” he says, adding it only accounted for less than 2% of it.
Patel also spent time studying cheetahs at wildlife sanctuaries near Cape Town and Johannesburg.
“At first, I just mounted GoPro cameras in the cheetahs’ enclosures. But of course, although the cheetahs did amazing manoeuvres, they didn’t do them in front of the camera,” he remembers.
Next, he created a special harness with a camera facing backwards that could be comfortably attached to the animals’ backs. “This worked much better, and we managed to capture how their tails moved,” says Patel.
Using smartphone technology, such as accelerometers, GPS and gyroscopes, Patel was able to capture a great deal of information in a short time.
This resulted in “some big datasets”, and Patel then formulated an algorithm that could combine all the pieces of information to produce a “coherent model of the skeletal movement of a cheetah”.
While discussing the invention with Saberi Marais, a staff member at UCT’s Research Contracts and Innovation department, they realised that “this way of capturing movement could also be applied to the human body”, says Patel.
Marais introduced Patel to scientists at the UCT Sports Science Institute
“Up until now, if a sports scientist wanted to study the movement of an athlete they would have had to do it on-site, in a custom setting, using motion-capture cameras,” explains Patel. This is often expensive and impractical.
The new system, on the other hand, uses multiple sensors that are “lightweight and economical”, yet very precise.
“Using a dozen such sensors attached to different parts of the body, I believe we can capture a very complex and nuanced picture of its movement – and we can do it remotely,” says Patel.
The invention promises to have a wide array of applications, including sports scientists analysing the movement of professional athletes and doctors gauging the effects of a stroke on a patient’s movement.

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