Disturbance Attenuation and Load Decouplingwith H 1 Positive Joint Torque

Positive joint torque feedback can compensate the detrimental eeects of load torques on position tracking performance. However, with (real world) non-ideal torque sources, simple unity gain positive torque feedback can actually deteriorate the performance, or even result in instability. An H 1 joint torque feedback is proposed which takes the dynamics and uncertainty of the actuator into account and minimizes the system's sensitivity to load torques. In our experimental direct-drive system, the H 1 positive torque feedback inner loop drastically improved the disturbance attenuation (25dB) and load decoupling properties of a simple PID position controller.