Robust position/force control of nonholonomic mobile manipulator for constrained motion on surface in task space

In this paper, a robust controller is developed for a mobile manipulator (MM) to track reference position/force trajectories. Nonholonomic and holonomic constraints are considered for the mobile platform and manipulator, respectively. Additionally, the control design considers the uncertainties in parameters of the dynamics of the mobile manipulator with a bounded time varying additive disturbance (unmodelled effects, external disturbances). A Lyapunov-based stability analysis is used to prove semiglobal uniform ultimate boundedness of the tracking error signals and the position/force of the system track to an arbitrarily small neighborhood of the reference trajectories. Numerical results for a mobile manipulator, which is formed from a differential drive mobile platform and 2 DOF Revolute-Revolute (RR) manipulator, show that the position of the end-effector and the applied force track the desired position and the force trajectories, respectively.