Analysis of the influence of braking control laws on gear walk

Abstract

The problem of gear walk on landing gear becomes increasingly serious. A rigid-flexible coupling dynamic half-axle main landing gear model, verified to be in accordance with the test data and the original deceleration control system, are built to study the gear walk problems. The co-simulation method is adopted. According to the severe gear walk phenomenon under the deceleration braking system, two modified braking control laws-only the reference speed-speed difference (with PBM) control and the one combining the PBM with the fuzzy control are designed for this type of airplane to weaken the gear walk. The simulating results show that the modified braking control law weakens the gear walk considerably. The braking frequency increases by about 17 %. The average wheel axle gear walk average amplitude decreases by 73 % and the longitudinal acceleration drops by about 91 %. The braking frequency decreases by 50 % so that the vibration frequency of the gear walk decreases by about 59 %. The combined braking control law is verified that is of great stability, adaptability and robustness under variable external conditions.