Adaptive Robust Trajectory and Force Tracking Control of Constrained Mobile Manipulators

This paper studies the simultaneous trajectory and force control problem of mobile manipulators subject to holonomic and nonholonomic constraints with uncertainties and external disturbances. The main feature of this paper is that 1) adaptive robust control strategies, which avoid complex regressor matrix, are presented based on a suitable reduced dynamic model, the defined references signals and the mixed tracking errors; 2) the proposed control schemes guarantee the states of the system asymptotically converge to the desired trajectory, and ensure the boundedness of the constrained force with controllable bounds at the same time; and 3) asymptotic stability in the Lyapunov sense is acquired and rigorously proven. A numerical example is presented to illustrate the developed method.

I. Introduction

A mobile manipulator consists of a mobile platform carrying a standard robotic arm. Such robotic system merges the dexterity of the manipulator with the increased workspace capabilities of the mobile platform, and thus is particularly suited for field and service robotic applications which require both locomotion and manipulation abilities [1] [2]. The nonholonomic kinematic constaints caused by the wheeled configuration, the complex physical structure, and the highly coupled dynamics between the mobile base and the mounted robotic arm are among the features that render the control of mobile manipulator very challenging.