Modular Formation Control for Multi-Mobile Robots With Collision Avoidance and Communication Maintenance

To further improve the safety and reliability of multi-mobile robot systems, this paper investigates the formation control problem with considerations of collision avoidance, communication maintenance and robots’ actuator bias faults. A novel modular formation control scheme, which consists of two modules, is established. In Module I, a formation signal generator is constructed based on graph theory, acting as a virtual multi-agent system through a network of double-integrator dynamic nodes. The outputs of the virtual multi-agent system (i.e., the generator) are designed to asymptotically form the desired formation shape while satisfying some designed specific constraints. Then, in Module II, extended-state observers (ESOs) are firstly employed to estimate and compensate for the actuator bias faults. After embedding the corresponding node within each robot and taking its outputs as formation references, some constrained ESO-based tracking controllers are designed based on back-stepping method. In general, the proposed modular formation control integrates collision avoidance, connectivity maintenance and fault-tolerant functions, while realizing the desired formation shape with bounded convergence of formation errors. Simulations and experiments demonstrate the effectiveness of the proposed modular formation control scheme.