Calibration taboo of electro-hydraulic servo system
1) The choice of lead and lag correction is taboo. In electro-hydraulic servo systems, series lag correction is often used to improve low-band gain and improve system accuracy. Or, under the condition of ensuring system accuracy, by reducing the mid-band gain of the system, the crossing frequency is reduced to ensure the stability of the system. Because for the hydraulic servo system with integral plus oscillation link as the main feature, the phase stability margin is easy to guarantee, and the assignment stability margin is not easy to guarantee, so it is not easy to use series advance correction mainly to improve the phase margin, but to use series Lag correction.
(2) Series lag correction should not be used alone. After using series lag correction, the response characteristics of the system have not been improved. The bandwidth of the actual system will also be reduced, and due to the reduction in phase margin and the change in the cut-off frequency during operation, it is possible to make the system into a stable system. Therefore, the series hysteresis correction should be used together with other correction measures.
(3) Don't ignore the difference between speed feedback correction and acceleration feedback correction. Speed ​​feedback correction is mainly to improve the rigidity and bandwidth of the system, and reduce the influence of interference and nonlinearity in the components enclosed in the speed feedback loop. The acceleration feedback is mainly to improve the damping of the system.
4) The effects of speed feedback correction and acceleration feedback correction are good. According to need, speed feedback correction and acceleration feedback correction can be used separately or simultaneously. Acceleration feedback can increase the system damping, and speed feedback can increase the natural frequency of the system, but reduce the gain and damping. If speed feedback and acceleration feedback are introduced at the same time, and K1 and K2 values ​​are appropriately selected, the damping ratio can be increased and the resonance peak can be lowered, so that the dynamic and static performance indicators can be comprehensively improved.
(5) Dynamic pressure feedback is better than pressure feedback. The use of dynamic pressure feedback electro-hydraulic servo valve can improve the damping ratio. If the structure of the electro-hydraulic servo valve is not changed, the load pressure is measured by the pressure sensor and converted into a voltage signal, and the proportional voltage signal is taken out through the differential circuit, and then the feedback loop surrounds more components, thereby improving Kyoto. Dynamic pressure feedback only plays a role in the dynamic process. The function of the pressure feedback is the same as that of the pressure feedback servo valve, which also generates an accessory pressure flow coefficient to make K. Increase, thereby increasing the damping ratio. However, the external disturbance force and the pressure signal can also be fed back to the input terminal to cause a larger static error of the system. Obviously, dynamic pressure feedback is better than pressure feedback.
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