Torque control with nonlinear compensation for harmonic drive DC motors

By controlling the torsional angle of the torque sensing element without using the torque sensor output, a high stiffness torque control system for geared DC motors has been proposed. This torque control system is successful when the torque sensor and the harmonic drive gear are modeled as linear springs. This paper describes a drive system observer added to the previous torque control system in order to compensate for nonlinearities of the drive system such as harmonic drive gears. The effectiveness of the proposed method was demonstrated by the experiments