Stable force control of one degree-of-freedom manipulator in contact tasks

Force control in contact tasks is discussed, and the system stability is proved theoretically using the Lyapunov direct method. A one-degree-of-freedom manipulator representing simple linear manipulators is treated. Some numerical simulations are executed both for the analysis verification and for the discussion of transient responses. As manipulators are mostly designed to do tasks acting on the environment and their home positions are in free space, the tasks naturally include contact. If the motion is fast enough, the interaction becomes collisional, which has up to the present time dominated the speed of the task because the motion at the contact has been controlled very slowly to avoid collision. In this paper, the stability of the motion is proved theoretically, and the contact, or collision, can be controlled with attention to the control law.