Balance control of ball-beam system using redundant manipulator

This paper proposes a control method of the redundant manipulator to balance the ball-beam system. Our system can be largely categorized as estimating the position and velocity of the ball, designing the controller to maintain the balance of the ball-beam system and controlling the redundant manipulator to move the beam. The Force/Torque sensor attached to the end-effector of the manipulator is used for estimating the ball position because the F/T sensor already attached to many manipulators in the service robots performs a variety of tasks. Estimated position of the ball involves significant noise because of the noise from the F/T sensor itself and estimating the ball position by using differentiation. We employ a state feedback controller with the observer to solve these problems. The control scheme of the redundant manipulator to control the ball-beam system is the based on the virtual spring-damper hypothesis. The proposed method enables the redundant manipulator to balance the ball-beam system even though the external forces are applied in both the elbow of the manipulator and the ball. Experiments to validate the proposed method to balance the ball-beam system are performed with the 7 degree-of-freedom redundant manipulator.