Study on compound control of high speed hydraulic torque-load simulator

With the rapid development of maneuverability of missile, the performance of hydraulic torque-load simulator that loads the air torque to the missile rudder becomes higher and higher. Especially to hydraulic torque-load simulator with high speed, the classical control method is difficult to reach the high performance. This paper presents a combined control method based on fuzzy, PID and phase-correction, which is suitable to high-speed (maximal speed is 500 degree per second) hydraulic load simulator. In the method, the fuzzy rules are modified to be sensitive to large error and large error-differential to increase the dynamic response, shorten the transition time. On the other hand, the fuzzy method is not sensitive to small error and small error-differential that can prevent to produce the small fluctuation in small range and avoid prolonging system response time. In the method, the integral coefficient of PID is used to improve the system stable accuracy. In order to enhance stiffness to exterior disturbance within operational frequency band (10Hz), a phase-correction unit is added to reduce the phase delay at 10Hz frequency point and the extraneous torque at high frequency is reduced rapidly. At the early stage of process of dynamic response, the modified fuzzy method is major to decrease the error and reduce the rising time, whereas the PID has major effect at the end of the stage of dynamic process to reduce the error within 5% error-band rapidly. The application with the new combined control method indicates that the transition time cuts down 40%. At 10 Hz frequency point,, phase delay is reduced from -10 degree to -3 degree. At the same time, extraneous torque generated by motion of missile rudder, reduces to 50%, that means no more than 20 N (.) m and the dynamic-tracing accuracy is close to 50% of classical method. In a word, the new combined control method not only is very effective in hydraulic torque-load simulator with high speed, but also is applied to those systems with large exterior disturbance.