Torque control of electrohydraulic servo system based on /spl mu/-synthesis theory

mu-synthesis control theory is applied to design a robust controller to deal with various system uncertainties for controlling torque in electrohydraulic load simulator (EHLS). The uncertainties which affect system performances to some extent are stated by theoretical analysis. An electrohydraulic load simulator prototype is used in experiments to test validity of this robust controller. 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 10Hz (double-ten index) which assures the error of amplitude less than plusmn10% and the lag of phase less than 10deg