ROBUST SPEED CONTROL OF A SECONDARY UNIT SYSTEM

Parameters of the secondary unit system, similar to other electrohydra ulic servo systems, change with the operating condition and time. It i s certain that the system performance will be affected. The applicatio n of the robust optimal controller in the speed control of a secondary unit system is examined in this paper. This controller consists of an optimal part and an auxiliary part. The optimal part is utilized for specifying the dynamic characteristic of the whole closed-loop system, which is designed based upon the ARMA (autoregressive moving-average) model. The auxiliary part is developed for rectifying the uncertainti es which a simple ARMA model is unable to handle. The robust optimal c ontroller is demonstrated from the results of a series of simulations and experiments to be superior to the suboptimal PI controller under t he situation of a change in working pressure and load inertia. The pro posed control scheme is also indicated by these results to be robust t o the external torque disturbance.