Mixed Sensitivity ∞ Controller Design for Force Tracking Control of Electro-hydraulic Servo System

The paper presents mixed sensitivity H-infinity controller design for force tracking control of electrohydraulic servo system. The system is inherently nonlinear and includes hard nonlinearity, like the nonlinear relationship between pressure and flow rate which effect system dynamics and deteriorate the nominal behavior of the system. To cope up with such a nonlinear function and enhancing the system performance, mixed sensitivity H-infinity controller is designed. A 3rd order linear time invariant model of system is identified based on input-output data from experimental setup. The weighting filters are included in the system in design phase and are tuned in such a way that the desire performance can be achieved. Simulation results on linear and nonlinear system show the better force tracking in comparison with linear quadratic regulatory control. The proposed technique is found robust in the presence of disturbance.