Best fit sensorless force control system considering environmental stiffness variation

This paper proposes a method of dynamic parameter tuning for a sensorless force control system with I-P(Integral-Proportional) current controllers. All free parameters of the whole system are determined theoretically by pole assignment method. This paper describes that gain of current controllers and estimation bandwidth of a disturbance observer have to be set according to stiffness of target environment, although gain of a force deviation and a quality factor of the disturbance observer are derived as constant values. In order to adapt to the stiffness variation, the proposed system changes dynamically the gain of I-P current controllers and the bandwidth of the disturbance observer. Furthermore, comparative experiments confirm that the force and I-P current control systems with dynamic parameter tuning is effective.