Robust H∞ control of a friction based electrohydraulic load simulator

In order to improve the torque tracking performance of a friction based electrohydraulic load simulator (FEHLS), first, the linear mathematical control model of the FEHLS is established according to its working principle. As an electrohydraulic servo system (EHSS), the FEHLS always has parameter uncertainties, measurement noise, external shock, etc. Besides, in practical applications, most of the state variables of the controlled EHSSs cannot be measured. In order to compensate for the aforementioned factors of the FEHLS and avoid the use of full-state feedback, a robust H
_∞
controller is designed to meet the requirements of highly accurate and highly dynamic torque tracking control. As compared with the proportionintegration-differentiation (PID) controller, the effectiveness of the robust H
_∞
controller is verified by the experimental results.