A unified motion control and low level planning algorithm for a wheeled skid-steering robot

In this paper a unified motion control and planning algorithm dedicated for the waypoint following task realized by a skid-steering is presented. In order to reduce excessive slip effects between robot wheels and ground it is assumed that the vehicle moves with bounded velocities and accelerations. The motion controller has been designed using formal methods to ensure asymptotically stable tracking of feasible reference trajectories. To account for practical motion tasks the trajectory tracking algorithm is complemented by a motion planner, which utilizes the differential flatness property of unicycle-like kinematics. During the motion planning stage an auxiliary trajectory connecting points in the configuration space and satisfying assumed phase constraints is generated. The resulting motion execution system has been implemented on a laboratory-scale skid-steering mobile robot, which served as platform for experimental validation of presented algorithms.