Pressure oscillation analysis of aircraft hydraulic braking system considering pipeline

Pressure servo-valve is usually used for aircraft hydraulic braking system, and the brake pipeline between the valve and the actuator is usually long. The long pipeline brings under damping frequency characteristic into the system, which will couple with the local close-loop pressure control structure of pressure servo-valve, and make pressure control oscillate easily. Based on a model considered pipeline for the hydraulic braking system, the reason of pressure servo-valve and pipeline coupling was analyzed. The influence of the changes in pipeline and oil parameters on pressure control was given. Simulations of the pressure control of aircraft hydraulic braking system were conducted to verify the frequency analysis. And three solutions for avoiding pressure oscillation, including matching design of pipeline, increasing the system damping and reducing the gain were also analyzed. Theoretical reference for the design and optimization of the aircraft hydraulic braking system was provided.