How Do Robot Swarms Behave Compliantly?

Conflicts often arise in swarm robotics between individual tasks related to environmental adaptation and the cooperative objective of maintaining a formation. For instance, obstacles may prevent robots from achieving a prescribed formation. Individual tasks, such as collision avoidance, are typically more urgent than the formation maintenance objective. As a result, it is necessary for the formation to compromise (i.e., be compliant) with these individual tasks, highlighting the need for swarm robots to behave compliantly. Inspired by the action principle of compliant control in physical robots, this paper proposes a distributed method that endows swarm robots with compliance. From the perspective of an individual robot, the method enables each robot to achieve its local tasks, allowing it to adapt to its environment. At the swarm level, the approach facilitates a compromise between formation maintenance and individual tasks, mitigating conflicts between individuality and collective objectives. Consequently, the swarm behaves compliantly, autonomously adjusting its formation shape. Finally, experimental results demonstrate the effectiveness of the proposed method, showing its ability to enhance the flexibility and adaptability of swarm formations.