Stable control of 1 degree-of-freedom linear manipulator based on force sensor in contact tasks

In this paper, contact motion control in force control is theoretically shown to be stable using sensor feedback information. The feedback for the manipulator consist of position and velocity of the manipulator and the impact/contact force. The system stability is analyzed by the Lyapunov direct method. Sufficient conditions for the stable control are suggested. The subject manipulator is a 1 degree-of-freedom linear system with force sensor, and it interacts a deformable wall with collision phenomena at the contact of tasks. The stability and the transient response of the system is examined by parameter studies of numerical simulation. As a manipulator´s “home” positions is in free space and does tasks acting on the environment, it naturally touches work pieces and includes contact. The contact becomes collision, if the motion is fast in any tasks. However, the contact phase dominate the speed of the whole task, because, so far, the motion at the contact is controlled to be very slow. In this paper, the stability of the motion is proved theoretically, and the contact, or collision, is shown to be controlled with stability using an ordinary feedback control law