Motion control systems with ℋ∞ positive joint torque feedback

In this work, a new ℋ^∞ joint torque feedback approach is proposed which takes into account the actuator´s finite bandwidth dynamics, and minimizes the system´s sensitivity to load torque disturbances and load dynamics. We also address implementation issues such as the development of a hydraulic dynamometer testbed for measurement of the disturbance sensitivity and of an innovative method for identifying the actuator dynamics. Experiment results with our experimental direct-drive motor demonstrate that the additional ℋ ^∞ positive torque feedback greatly improves the disturbance attenuation and load decoupling properties of a simple PID motion controller. The optimal torque feedback also reduces the tracking error when dealing with a dynamic load while, unlike the conventional unity joint torque feedback, maintaining robust stability