Hydraulic Servo System Control Using Differential Evolution Based Robust Structure Specified H∞ Controller

Synthesis of an H∞ controller usually produces a very high order of controller, and one which is much higher than the plant, causing difficulty in implementing the controller in practical applications, especially those using small microcontrollers. However, systems are always subject to disturbances and un-modeled dynamics. This research introduces modeling and simulations of lower order structures, specifically an H∞ robust controller, to control a hydraulic servo system. A low order controller shortens the gap between the complicated H∞ controllers to the practical embedded control system application. Simulation results show that the proposed controller gives satisfactory results with small settling times and no steady state error. The resulting controller also produced better responses than that of a full order H∞ controller generated using the Matlab Robust Control Toolbox.