Mathematical Model and Vibration Analysis of Aircraft with Active Landing GearSystem using Linear Quadratic Regulator Technique

This paper deals with the study and comparison of passive and active landing gear system of theaircraft and dynamic responses due to runway irregularities while the aircraft is taxying. The dynamicload and vibration caused by the unevenness of runway will result in airframe fatigue, discomfort ofpassengers and the reduction of the pilot’s ability to control the aircraft. One of the objectives of thispaper is to obtain a mathematical model for the passive and active landing gears for full aircraft model.The main purpose of current paper is to design linear quadratic regulator (LQR) for active landing gearsystem that chooses damping and stiffness performance of suspension system as control object.Sometimes conventional feedback controller may not perform well because of the variation in processdynamics due to nonlinear actuator in active control system, change in environmental conditions andvariation in the character of the disturbances. To overcome the above problem, we have designed acontroller for a second order system based on Linear Quadratic Regulator. The performance of activesystem is compared with the passive landing gear system by numerical simulation. The results ofcurrent paper in compared with the previous work mentioned in reference, demonstrates 37.04%improvement in body acceleration, 20% in fuselage displacement and 13.8% in the shock strut travel.The active landing gear system is able to increase the ride comfort and good track holding by reducingthe fuselage acceleration and displacement and load induced to airframe caused by runway excitation.