Damping control with consideration of dynamics of environment

Most of the explicit force control algorithms published so far assume the switching of the control law from position control to force control when a transition occurs from a free motion to a constrained motion, but the ideal switching of the control law is impossible for a rapid transition. Implicit force control algorithms, such as stiffness control, damping control, impedance control, etc., can be applied to both free motion and constrained motion without switching the control law. However, precise force control is difficult, especially with nonrigid environments. The authors propose an alternative force control algorithm for nonrigid environments based on damping control, so that the transition occurs naturally. They model a damping control system with environmental dynamics and design a predictive control algorithm so that the force is precisely controlled when the motion of the robot is constrained. The proposed method is applied to a manipulator with one degree of freedom, and experimental results illustrate the validity of the method.