Science Article

A military reconnaissance robot being developed at a British lab can keep moving even if it gets damaged on the battlefield. When any of the snake-like robot's "muscle" segments are damaged, clever software "evolves" a different way for it to wriggle across any terrain. The serpentine spy is a research project funded by aerospace company BAE Systems to make a low-cost military robot that can be dropped out of helicopters to carry out reconnaissance missions. 

A self-healing robot has long been a dream of robotics engineers, not least because the machines are notoriously unreliable and absolutely terrible at dealing with unforeseen circumstances. The snakebot is made up of modular vertebral units that "snap" together to form a snake-like body (see picture). 

Shape-memory Alloy

Each unit contains three separate "muscles" running down its length. The muscles are made out of wires of a shape-memory alloy called nitinol, an alloy of nickel and titanium whose crystal structure shrinks when an electric current is applied to it. Usefully, it regains its original shape and length once the current is removed.

To make the snakebot move in a particular direction, a current is applied to certain wires. When the current is removed, the wires spring back and the robot will jump forward.

The software for making a robot wriggle like a snake is fairly straightforward. But ensuring that the snake will keep moving even if a segment is damaged is trickier, and relies on different segments taking over from the damaged ones.

Genetic Algorithm

The program starts off with a population of 20 digital chromosomes, with each consisting of an initially random binary digit that corresponds to a muscle wire - where a 1 represents its activation and a 0 its deactivation. Each of these chromosomes forms the basis of a series of movements in the robot.

The two best chromosomes are then saved, the remainder are mixed up or randomly mutated and the process is repeated. After a number of generations, the amount of improvement finally tends to taper off.

Bentley and his colleague Siavash Haroun Mahdavi at University College London borrowed a trick from evolution to allow their robot to adaptive ability and so tend to give up the ghost when circumstances change.

So, they make a bot like snake, thr name of is SNAKEBOT.