Fault-Tolerant Flocking of Mobile Robots with Whole Formation Rotation

Consider a system composed of mobile robots (mobile sensors) that move on the plane, each of which independently executing its own instance of an algorithm. Given a desired geometric pattern, the flocking problem consists in ensuring that the robots form this pattern and maintain it while moving together on the plane. In this paper, we look at the flocking problem in the presence of faulty robots, where the desired pattern is a regular polygon. We propose a distributed algorithm assuming a semi-synchronous model with a k-bounded scheduler, in the sense that no robot is activated more than k times between any two consecutive activations of any other robot. The algorithm is composed of three parts: failure detector, ranking assignment and flocking algorithm. The rank assignment part is to provide a persistent ranking for the robots in the system. Then, the failure detector can select the set of correct robots from all the robots. Finally, the flocking algorithm handles the movement and reconfiguration of the flock, while maintaining the desired shape. The difficulty of the problem comes from the combination of the three parts together with the necessity to prevent collision and allow the rotation of the flock. Different from the existed work, our algorithm can make the formation rotate freely and has good maneuverability.