Motion and squeeze force control for omnidirectional wheeled mobile robots

For a redundantly-actuated wheeled mobile robot, the squeeze force between the robot body and its wheels does not contribute to the motion of the robot, but to squeeze the related rigid bodies each other. It is good to control the squeeze force, regulate it to zero if possible, from the view of energy efficiency or life span of joint components. Thus a scheme controlling robot motion while controlling squeeze force is proposed as the following procedure: After a stable controller is presented for robot motion control, a squeeze force controller is designed to regulate the squeeze force to zero. The proposed scheme is demonstrated in robot regulation and tracking control problem. A "PD+" controller is adopted for robot regulation, a modified inverse dynamics control is applied for robot tracking control. In both robot control problems, an integral feedback squeeze force controller is used to minimize the squeeze force. The presented simulation results verify the effect of the proposed scheme.