Non-model based adaptive control of electro-hydraulic servo systems using prefilter inversion

In this paper, a novel non-model based adaptive controller “NMAC” is introduced. The algorithm developed for this controller takes place by inverting the inverse adaptive filter preceding the controlled plant. Two NLMS algorithms are run simultaneously in order to invert both the real plant and the obtained inverse prefilter. This algorithm has been used for position and tracking control of a hydraulic servo system. The control system performance was compared with that of a PPT₁ feedback controller, standard “FXLMS” algorithm, and a robust H-infinity controller. The proposed controller has shown that a final tracking accuracy can also be achieved in case of transients even in presence of disturbances and uncertain nonlinearities. This controller can also be implemented without using a plant model with parameter estimation to meet the adaptability requirement, which is considered the main advantage in comparison with the other controllers.