Formation tracking control for a class of multiple mobile robots in the presence of unknown skidding and slipping

This study investigates the formation control problem for a class of multiple mobile robots considering unknown skidding and slipping, and torque saturation. The kinematics and dynamics of multiple mobile robots with skidding and slipping effects are considered. The proposed formation control scheme is derived from the dynamic surface design and virtual structure approach where the reference trajectories consisting of path parameters are employed to satisfy both the tracking control and the formation maintenance. The adaptive technique is used to compensate the unknown skidding and slipping effects. From Lyapunov-stability analysis, we prove regardless of unknown skidding and slipping that all signals of the total closed-loop system are semiglobally uniformly ultimately bounded and the point-tracking errors and the synchronisation error for the desired formation converge to an adjustable neighbourhood of the origin. In addition, it is analysed that the orientation error for each robot is related to the speed of the reference trajectory and the skidding effect. The performance and stability of the proposed approach are verified from simulation results.