A Control Method Switching from Servo Automatic Transfer to Force Sensorless Impedance Control Manual Positioning

The applications of power-assist systems (PASs) to manufacturings have attracted special interest recently. Many PASs for industrial uses possess simple power-assisting function only. Conveyance of controlled objects is generally processed by another system. One of the authors has studied on the positioning method of a cart with motor using a smooth switching from the servo access control for the conveyance function to the impedance control for the power-assisting function. The nonstationary optimal control method and the nonstationary impedance control law are applied to obtain the smooth switching. However, this method requires a force sensor for detecting the operator´s force. To improve the usefulness and safety of the system, a force sensorless control method for the system is studied in this paper. This study utilizes the acceleration signal of the cart instead of the force signal. The method shows its effectiveness by experiments.