Here’s how mathematicians might define the sport of wrestling. A system composed of two mechanical agents coupled via mechanical actions such as contact and collision. The aim of the contest is for one agent to floor the other while maintaining its own balance. The rest is just show business.
That’s more or less exactly how Katsutoshi Yoshida and pals at Utsunomiya University in Japan describe the sport in developing a mathematical model of wrestling which they go on to test in a numerical simulation.
The end result is a pair of autonomous mechanical wrestlers that compete to topple each other.
Their model is simple in principle. Each wrestler is an inverted pendulum on a cart that can move backwards and forwards, a bit like balancing a pencil on your finger.
These robot ‘wrestlers’ are joined at the tips by a spring that can stretch and compress. That means one wrestler can pull or push the other over.
However, the opposing wrestler can take evasive action by moving in a way that stabilises itself and unbalances its opponent. The contest is over when one wrestler or the other falls to the ground.