Simulation And Test Study On Active Hydro-Pneumatic Suspension And Hydraulic System

Hydro-pneumatic suspension and launching pad is most important components to missile vehicle because theirs performances greatly affect the flexibility and veracity of missile vehicle directly. Hydro-pneumatic spring is a part which determines the ride comfort and handling stability of vehicle. Hydraulic system can adjust body attitude and launching angle. In order to analyze the overall vehicle performance, it's important to know how to construct the accurate model of hydro-pneumatic spring and hydraulic system. Therefore, it's a foundation and significance for dynamic research of vehicle.Based on the practical project, the study on simulation and test study on hydro-pneumatic spring and launching pad is presently in this dissertation. The main research includes:1. Simulation model and test study on Hydro-pneumatic springFirstly, by taking into account the nonlinear characteristics of spring stiffness and the dynamic friction between hydraulic piston and cylinder wall, the nonlinear mathematical model of hydro-pneumatic spring is built. The simulations are performed in different excitation frequencies and amplitudes. The accuracy of mathematical model is verified by comparing the simulation curves and the experimental data. Then, analyze the effect on characteristic of hydro-pneumatic caused by changing the main parameters of the structure. Finally, based on the established mathematical model, the spring stiffness, the damping characteristics in different speeds are respectively investigated.2. Control method and simulation of active hydro-pneumatic suspensionSuspension is one of the most important components of the vehicle, which connects the wheel and vehicle body flexibly,plays an important role in effecting the multiple performance of vehicle. Meanwhile, suspension is a very complex assembly, so it's necessary to construct the correct model. At first, analyze the electro-hydraulic servo system which acts as an actuator. Then, the nonlinear damping valve and the accumulator of the hydro-pneumatic spring are linearly simplified based on the stability analysis, and a linear quarter vehicle model with active hydro-pneumatic suspension is built. In the research into the suspension control theory, LQG theory is in the dominant position. First the road signal is random, so the acceleration of the road can be taken as white Gaussian noise, and the performance of the suspension can be expressed with quadratic functional differential equation. On the other hand LQG theory provide perfect tool for the state feedback and output feedback.3. Simulation of hydraulic system model of launching padFirstly, analyze the hydraulic system of launching pad. Hydraulic power, erecting system and leveling system are the most important subsystem according to the requirement of launching pad. So, balance valve and speed control valve should be put great emphasis on. However, proportional overflow valve response is slower than balance valve and speed control valve that the analysis of dynamic process was neglect in this chapter. Then, to construct the model in MATLAB/Simulink software to analyze the effect of hydraulic parts.