An Adaptive Control of an Electro-Hydraulic Position Control System

In a hydraulic system input/output relation of the control valve is nonlinear and load dependent. An adaptive control would therefore be necessary for large changes in load parameter. The paper considers a position control system. This becomes a third order system under inertia load and with compressibility of oil considered. Load pressure and integration of the load pressure are suggested as additional feedbacks. PRBS is used as the input signal and the cross-corelation technique is used for identification of the impulse response. Performance parameters are defined and then they are brought to their respective model parameters by iteratively adjusting the gains of the additional feedback loops. An 8-bit microprocessor based system has been used for identification and control. The proposal seems practical and can be economically implemented.