Semi-active control of aircraft landing gear system using H-infinity control approach

The landing of an aircraft is one of the most critical operations because it directly affects the passenger safety and comfort. During landing, the aircraft fuselage undergoes excessive vibrations that cause the safety and the comfort problem and hence need to be suppressed quickly. A semi-active control system of a landing gear suspension by using Magnetorheological damper can solve the problem of excessive vibrations effectively. In this paper, a switching technique is developed in the simulation of the landing procedure which enables the system to switch from the single degree of freedom to three degrees of freedom system in order to simulate the sequential touching of the two wheels of the main landing gears and the nose landing gear wheels with the ground. A semi-active Magnetorheological damper is developed using two different controllers namely linear quadratic regulator and the H∞. Spencer model is used to predict the dynamic behavior of the Magnetorheological damper. The results of the designed controllers are compared to study the performance of the controllers in reducing the overshoot of the bounce response as well as the bounce rate response. The simulation results validated the improved performance of the robust controller compared to the optimal control strategy when the aircraft is subjected to the disturbances during landing.