A method of change of force sense for series connection type master slave actuator (To change of force sense without changing mechanical component)

Abstract

In recent years, surgical robots have come into wider use. These robots do not yet provide a force sense to the surgeon, but such force sense will be necessary on the next generation of surgical robots. When the slave motor needs to generate a larger or smaller driving force than the master motor, mechanical gearing is normally used. This leads to large mechanical losses. A small force sensed at the slave cannot be transmitted back to the master. We have proposed a master-slave system of the series connection type that generates a force sense using conventional bilateral control. However, when linking together motors of different output power, the allowable current of the small power output motor is insufficient to drive the large power output motor. We now propose a method that combines a motor with a shunt resistor. If a resistor is connected to a motor in parallel, the allowable circuit current increases, removing the current limitation and increasing the circuit current. This approach also allows the variable force to be sensed by changing the shunt resistor. We experimentally confirmed the effectiveness of the proposed method. In this paper, the principles of using a shunt resistor for changing the force sense are explained, and our experimental results are presented.