Study on Passive Torque Servo System Based on H∞ Robust Controller

Regarding surplus torque as disturbance and considering various system uncertainties in a passive torque servo system, a controller is designed based on H-inflnity (H∞) robust control theory. Simulation works of system characteristic is finished using such a controller with various uncertainties as well as some static and dynamic characteristics experiments. Simulation and experimental results show that the controller not only works well for various dynamic set-point load, but reveals insensitive to the variation of parameters which change with work condition, to the unmodelled dynamics and disturbance. The controller provides sufficient stability and performance robustness to the system. The undisturbed closed-loop bandwidth of system reached at 15 Hz which assures the error of amplitude less than ±10% and the lag of phase less than 10°(double-ten index), and the disturbed closed-loop bandwidth of system reached at 10 Hz (double-ten index).