Working with large robot swarms
It is impossible to study swarm behaviour with just a couple of robots. That is why the team used at least three hundred in most experiments. Working with hundreds of tiny robots is a challenge in itself. They were able to do this thanks to a special setup which makes it easy to start and stop experiments, and reprogram all the robots at once using light. Over 20 experiments with large swarms were done, with each experiment taking around three and a half hours.
Furthermore, just like in biology, things often go wrong. Robots get stuck, or trail away from the swarm in the wrong direction. “That’s the kind of stuff that doesn’t happen in simulations, but only when you do experiments in real life”, says Ivica Slavkov, who shares first authorship of the paper with Daniel Carrillo-Zapata.
All these details made the project challenging. The early part of the project was done in computer simulations, and it took the team about three years before the real robot swarm made its first shape. But the robots’ limitations also forced the team to devise clever, robust mechanisms to orchestrate the swarm patterning. By taking inspiration from shape formation in biology, the team was able to show that their robot shapes could adapt to damage, and self-repair. The large-scale shape formation of the swarm is far more reliable than each of the little robots, the whole is greater than the sum of the parts.
Potential for real world applications
While inspiration was taken from nature to grow the swarm shapes, the goal is ultimately to make large robot swarms for real-world applications. Imagine hundreds or thousands of tiny robots growing shapes to explore a disaster environment after an earthquake or fire, or sculpting themselves into a dynamic 3D structure such as a temporary bridge that could automatically adjust its size and shape to fit any building or terrain. “Because we took inspiration from biological shape formation, which is known to be self-organised and robust to failure, such swarm could still keep working even some robots were damaged.“ says Daniel Carrillo-Zapata. There is still a long way to go however, before we see such swarms outside the laboratory.
James Sharpe (EMBL Barcelona) led the Swarm-Organ project, which was initiated at the Centre for Genomic Regulation (CRG) when Sharpe was a group leader there. Sabine Hauert (Bristol Robotics Laboratory and University of Bristol) was the key senior collaborator. Other collaborators were Fredrik Jansson (currently employed at Centrum Wiskunde & Informatica – CWI) and Jaap Kaandorp (University of Amsterdam – UvA).
The research leading to these results has received funding from the European Union Seventh Framework Programme (FP7) under grant agreement n° 601062, and the EPSRC Centre for Doctoral Training in Future Autonomous and Robotic Systems (FARSCOPE) at the Bristol Robotics Laboratory.