Hierarchical-security formation control of multiple wheeled mobile robots on multi-target surrounding with collision avoidance

This article investigates multi-target surrounding with collision avoidance for multiple wheeled mobile robots (WMRs) under a hierarchical-security formation control scheme. Multi-target surrounding requires WMRs to estimate and track targets’ center. Collisions happen between WMRs due to the estimator’s convergence errors or controllers’ tracking errors exceeding safety distance. Regarding this issue, a hierarchical-security control scheme is proposed for WMRs on multi-target surrounding task. In the first layer, a signal generator is constructed with primary security regulation to track the states of targets’ center estimator. In the second layer, a kind of trajectory tracking controllers containing secondary security regulation are designed for WMRs to track the reference signals from the previous layer. Compared with existing methods, the proposed control scheme improves the versatility of formation control methods for WMRs by modifying reference signals instead of controllers’ dynamic parts. Meanwhile, it uses local information to limit barrier function gains which ensures the smoothness of the generated reference trajectories. Finally, the effectiveness of proposed control scheme is verified by simulations and experiments.