Robust Formation Tracking of Multiple Wheeled Mobile Robots Under External Disturbance.

In this paper, we focus on formation tracking problem of multiple wheeled mobile robots (MWMRs) under external disturbances. First, the MWMRs’ formation tracking problem is reduced conceptually to track a trajectory by a virtual wheeled mobile robot (WMR) with placeholders that describe the desired position of each WMR in formation. Therefore, the moving trajectories correspond to each WMR can be obtained with placeholders. Second, a constraint minimization scheme, which incorporates WMR’s velocity limit, trajectory tracking simultaneously, is formulated from the perspective of optimization, where velocity norm is chosen as cost function. In this minimization scheme, an integration-enhanced error functional evolution formulation is introduced, aiming at resisting external disturbances. Then, a Lagrangian-based controller is designed to solve and output the velocities of WMRs’ left and right tires to control each WMR. Finally, simulation experiments verify the effectiveness of the proposed control scheme and robustness against noise.