Simultaneous base and end-effector motion control of a nonholonomic mobile manipulator

This paper investigates the motion control for a nonholonomic mobile manipulator with the objective of simultaneously controlling the velocity of the mobile base and the motion of the end-effector. Both the reference velocity for the mobile base and the reference trajectory for the end-effector are specified in the task-space. A steering velocity is designed based on the steering system of the mobile base via dynamic feedback linearization, with the advantage of directly using the reference velocity set in task-space. A torque controller is subsequently designed via backstepping based on the dynamics of the mobile manipulator to ensure that the mobile base tracks the designed steering velocity and the end-effector tracks the reference trajectory. The asymptotic stability of both the velocity tracking error and the end-effector motion tracking error is achieved. Simulations are conducted to demonstrate the effectiveness of the proposed controller.