Force and motion control for cylindrical curved surface wall using a three-link arm

For operation of robot arm when its end-effector contacts the arm's environment, force and motion control is necessary. Force and motion control for cylindrical curved surface wall using a three-link arm having spring end-effector was carried out by experiments and simulations. Low stiffness of the end-effector's spring by converting the force into compression displacement can absorb unknown high stiffness of robot and environment such as robot flexible joints, a force sensor and a reaction wall. Experimental results of velocity based control and torque based control show that the spring on the end-effector is useful for controlling reaction force. Experiment results using wrong desired trajectory shows that force feedback is effective to modify to the correct motion and force. But controlled reaction force has some fluctuations. Mechanical damper or controller for damping will be needed for spring on the end-effector.