Coordinated trajectory tracking for a group of mixed wheeled mobile robots

Coordination between a specific mobile robot types has been widely investigated, e.g coordination between unicycles. To extend the applicability of the system, coordinated trajectory tracking of mixed type of mobile robots is considered. We extend and prove the concept that if a certain type of wheeled mobile robot is able to individually track its own references, then coordination in tracking with other type of robots can be achieved simply by sharing individual tracking errors. Using two type of wheeled mobile robots namely unicycle type (a nonholonomic mobile robot) and omni wheels type (a holonomic mobile robot), a coordinated control algorithm can achieve a global asymptotically stable condition of the error dynamics of the systems. Although communication between robots has to be done bidirectionally, the overall group is able to maintain individual tracking while coordinating the movements with other robots regardless the occurring perturbations in the system. Simulation results suggest that information sharing between the robots increase the robustness in coordinating individual trajectories.