A smooth switching from power-assist control to automatic transfer control and its application to a transfer machine

Power-assist system technology and its application to manufacturing systems have attracted special interest recently. For example, automobile assembly processes utilizing power-assist systems exist. Many power-assist systems for industrial uses possess simple power-assisting functions only. The transfer of controlled objects is generally processed by another system. This paper proposes a transfer control method for a cart with motor by means of a smooth switching from the impedance control realizing the power-assist to the servo control for automatic transfer. To obtain the smooth switching, this paper utilizes a nonstationary impedance control method whose impedance parameters are time varying. A linear quadratic integral control method based on time-varying feedback gains is also introduced. By considering the setting of the time-varying parameters, the control characteristic is smoothly varied without control input saturation. This method increases the efficiency of control processes and realizes comfortable work for operators. The effectiveness of the method is verified by experiments and simulations.