Torque control of harmonic drive gears with built-in sensing

Force control is an important segment of intelligent motion control systems. To provide a high quality force control, it is necessary to make a bandwidth of the system as high as possible. Force or torque sensing therefore should be built into the existing components of a system. We study a possibility to build torque sensing into a harmonic drive gear reducer. Positioning of the strain gages to cancel the signal modulation is proposed. High linearity of sensing is achieved. Torque control by using a torque disturbance observer is implemented to improve static and dynamic characteristics of a control system with harmonic drive gear reducer. Experimental results of torque control are shown.