Rescue robot’s secret lies in cheetah tail
AS a boy, Amir Patel was fascinated by how animals moved. He was equally fascinated by robotics.
Today, after studying the secret life of a cheetah’s tail, he is a step closer to creating the ultimate search-and-rescue robot that could find and pull survivors and bodies from the scene of a mass disaster — without falling over.
By studying precisely how a cheetah uses its tail for stability during high acceleration, quick turns and sudden braking, he is able to simulate its sophisticated design for robotics.
Although it is known that the tail acts as a rudder or counterweight on the cheetah’s body, it took in-depth research to find out exactly how it worked.
It did not happen overnight. “First, I watched hours and hours of wildlife documentary footage — much in slow motion — to see how the cheetah was using its tail for stabilisation.”
He also contacted the cheetah sanctuary in Somerset West and became a regular “participant” in its weekly exercise regime.
“The cheetahs chase a rabbit skin and they go around in BIO-INSPIRED ROBOTICS: Amir Patel with the robotic ‘cheetah’ he built at the University of Cape Town circles to keep them well exercised. This was an opportunity to put cameras in different positions to see what the tail did when.”
Next was the more complicated task of writing the code for a programme that could simulate the tail’s design.
“We then modified a highspeed radio-controlled car based on what we had learnt, and took it down to the rugby field to test it.”
Patel also took part in a cheetah autopsy at the Pretoria zoo, which provided a vital clue.
“Up until that point, we thought the tail was thick and heavy and constituted about 10% of the body weight. But it is actually very skinny and light, only 2% of the body weight. But the bushiness of the fur on the tail is a key to how it works.”
Patel put some tail fur in a wind tunnel. It revealed that the aerodynamic properties of the fur create enough drag to assist enormously with stabilisation during sudden movements.
This, coupled with an understanding of what the various moves and swipes of the tail do in different situations, has taken Patel on his journey of what he calls “bio-inspired robotics”.
“We shouldn’t just mimic animal movement in robotics; we should first understand how and why they are designed like that.”
Part of his mission is to create robotics that can handle the rough terrain of real life.
He says robots “carefully calculate precise motions and operate in ideal conditions like laboratories”. Animals, however, are highly agile but must operate in rough landscapes.
For the cheetah, it is instinct: a flick of the tail to prevent falling over when braking quickly, a conical movement of the tail during a longer turn while at a gallop, and many other laws of physics that come naturally.
Johann Marais, of Wilderness Search and Rescue, said advances in robotics could make “a real difference to rescue missions”. He said sophisticated robots on the ground could work well with search drones.