ROBUST-CONTROL OF MOBILE MANIPULATORS

A mobile manipulator is basically a manipulator mounted on a mobile ve hicle. This arrangement has some advantages over stationary robots and mobile robots, such as the infinite workspace and the ability to avoi d singularities. However, the control problem becomes a sophisticated one. This is due to the nonlinear and nonholonomic constraints governi ng the motion of the vehicle. Moreover, the dynamics of the manipulato r and the vehicle are highly coupled; ground-surface irregularities, f or example, affect the motion of the end effector kinematically and dy namically. A mobile manipulator is expected to pass through different environmental conditions, a fact which calls for a robust control sche me. Unfortunately, the robust control problem for nonholonomic systems is not well defined yet. Since the ultimate goal of control is to con trol the motion of the manipulator's end effector, it is proposed in t his article to tackle the robustness issue by designing a manipulator decoupling controller. This controller aims at rejecting disturbances arising from the motion of the vehicle. (C) 1996 John Wiley & Sons, In c.