Positioning of a cart by means of a smooth switching function from servo access control to impedance control

Power-assist system technology and its applications to manufacturing systems, rehabilitation and welfare services have attracted special interest recently. In the field of manufacturing systems, automobile assembly processes utilizing power-assist systems exist. Many power-assist systems for industrial uses possess simple power-assisting function only. Conveyance of controlled objects is generally processed by another system. However, it seems that the progress of such actuators as linear motors produces single actuator which realizes both the functions. Taking the above expectation into account, this fundamental study proposes a positioning method of a cart with motor by means of a smooth switching from the servo access control for the conveyance function to the impedance control for the power-assisting function. We apply the idea of the nonstationary optimal control method to obtaining the smooth switching. The controller is formulated as a state feedback style utilizing time-varying feedback gains. The effectiveness of the method is verified by experiments.