An adaptive controller which is robust against unknown load disturbance is proposed in an electrohydraulic velocity control system. Since the load disturbances degrade the performance of a controller such as a steady state error and rising time in the conventional control system, the appropriate adjustment of a controller is necessary in order to obtain the desired performance.
Thus the adaptation mechanism is designed to adjust the feedforward gain to optimum based upon the near time optimal performance. The unknown load disturbance can be identified by using an analog computer from the relationship between the velocity of the hydraulic motor and the load pressure.
The proposed controller shows a better performance than the conventional P-controller in terms of the steady state error despite of a large variation in load condition, and stability is improved in the designed adaptive system.
