HYDRAULICS IN MISSILES
Nowadays, the electro-hydraulic actuator plays an important role in some modern tactical missiles. High power, great robustness and high tracking precision are the most significant demands for the missile actuator. Therefore an advanced method of active disturbance rejection control (ADRC) is presented aiming at the dynamics of the system are highly nonlinear and have large extent of model uncertainties, such as tremendous changes in load. Firstly, a novel ADRC controller is designed for estimating and compensating disturbance based on the mathematical model of missile electro-hydraulic actuator. Then, the influence of rudder load on the system performance is analyzed in this paper. Simulation results show that the ADRC control approach can decrease the tracking error and enhance the robustness of missile electro-hydraulic actuator system when the rudder load changed tremendously. But the phenomenon of Anti-Control has disadvantageous effect on the transition period of actuator loop and evenly causes the system divergence.
HYDRAULIC SUSPENSION IN BOGIES
The application of oil-hydraulic actuators for active suspension of railway vehicles has been examined experimentally by using a 3-DOF half-vehicle model. The LQG control law was adopted, in which state variables were estimated from measurable ones on the actual railway vehicle. The results show the possibility that the controllable frequency range extends with the oil-hydraulic actuator. The addition of bogie acceleration measurement to body related measurement provides a significant advantage for the performance. When actual body weight becomes lighter than that of the controller design value, the control performance and the stability deteriorate. Therefore, it is recommended to use the empty car body weight for design of the active suspension controller. The control effect can reach to the maximum vibration isolation level by shortening the sampling period to 2 ms
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