The present study deals with the adaptive control of an electrohydraulic servomotor system. A model reference adaptive controller has been designed to compensate for parameter changes such as load and oil viscosity. A digital system has been adopted because the controller has to carry out a lot of multiplyinga nd integrating operations, and a discrete-time theory is used to realize the precise control. An experimental apparatus was constructed consisting of an electrohydraulic servovalve, a servocylinder, an inertial load and the adaptive controller with a microcomputer. In order to evaluate the characteristics of this system, a simplep osition feedback system was also constructed. Experiments were carried out to compare the characteristics of the system with the adaptive controller to those of the simple feedback system. Simulation was also carried out using the microcomputer to facilitate the change in the parameters. The experimental and simulation results show that the system with the adaptive controller is proved to be much better at quality of control compared to the simple position feedback system; the former system responds very quick to the signal to be tracked, independent of the changes in inertial load and oil temperature.

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A method has been developed to decrease flow force by circulating the flow formed in compensation buckets of spoolv alves. Howevert, here is very little experimental and analytical data on the flow circulated in a compensation bucket. Thus, in this research, the effects of the geometric parameters of the bucket on the flow force have been measurede xperimentally. Three-dimensional visualization experiments to showt he relation betweenthe flow pattern and flow force compensation have also been carried out and the validity of conclusions obtained from flow force experiments was verified.

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