Thursday, 12 February 2015

Self-Organising Tiny Robots: Kilobots


I was simply awed by the sheer intelligence and simplicity when I read about Kilobots. The marvellous, small few centimetres in diameter robots, standing on three pin legs, powered by coin batteries were developed in the laboratory of Professor Radhika Nagpal and Fred Kavali of Harvard School of Engineering and Applied Sciences. A kilo or a swarm of 1024 autonomous robots assemble into two-dimensional pattern formation upon instructions without human intervention. An initial set of instructions are beamed to the robots via infrared following which the robots would work autonomously. Four robots mark out origin of a coordinate system and the remaining will receive a 2-D image they have to mimic. Using primitive behaviour, robots follow the edge of the group, track the distance and maintain a sense of relative position. They take turns in moving towards an acceptable position and assemble into the pre-directed shape. Kilobots communicate with its neighbour through and in built infrared transmitter. They have no sense about their broader outer environment. They can locate the position of their neighbours and their point of origin and are capable of assembling into a shape by gauging the position of its neighbour.

Kilobots are very simple in design and their abilities are variable and less reliable. They are basically designed to carry out collective tasks. Just as trillions of cells that constitute a complex organism communicate with each other and carry out complex tasks. These robots demonstrate how complexity can arise from simple behaviours performed enmasse.

The team basically drew inspiration from biological systems where individuals assemble to carry out tasks. An army of ants by relaying information among themselves construct bridges and rafts to cross difficult terrains. Similarly social amoebae cooperate with each other especially when food is scarce to form a huge fruiting body and escape the harsh external environment. Even the individual cells of cuttlefish change colours to blend into its surroundings. Nagpal has earlier developed a swarm of robots TERMEs inspired by termites but its algorthim for self-assembly wasn’t demonstrated. Kilobots were inspired by the collective functioning of a colony of ants. Till date robot swarms of around 100 were constructed. Kilobots are thus a unique creation wherein coordinated action of tiny 1024 robots is demonstrated.

To cut down the cost of constructing kilobots, certain tradeoffs are made. It has a simple design and moves with two vibrating motors which allows it to slide across a surface on its rigid legs. They have built in infrared receiver and transmitter to communicate with neighbouring robots. It is myopic and has no access to birds-eye view. It can’t move in a straight line as a result its abilities are more variable and less reliable. But the strength of the swarm overcomes individual weaknesses. With the smart algorithms it can overcome its limitations and can complete human-specified tasks of assembling into a particular shape with precision. These robots are capable of correcting mistakes. If they sense traffic jam, robots moves off the course, nearby robots sense the problem and cooperate to fix it.

Kilobots functioning can be represented as a milestone for the computer scientists in the development of collective Artificial Intelligence (AI). The development of kilobots is exemplary due to inherent difficulties of algorithmic limitations on coordinating large numbers and the cost of the labour involved in fabricating such tiny devices. Kilobots are test bed for Artificial intelligence and are manipulated to carry out collective tasks. Increasingly, robots are now required in coordinated tasks like environmental clean-up or disaster relief and for self-driving on highways. The potential for such swarms is huge in construction, agriculture, mining and medicine.
 
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