Abstract: In this article active control landing gears are designed to alleviate vibration during aircraft taxiing. A nonlinear stochastic dynamic model is established which takes into consideration aircraft body pitch movements and the elastic vibration excited by the random runway. The statistical linearization method is adopted to ensure the linearity of the model near the balance point, and the Gaussian random process of the runway is generated from the Gaussian white noise by a shape filter. Based on the stochastic optimal control theory, a linear quadratic Gaussian (LQG) controller is designed with weighted quadratic performance index related to comfort, shock absorption, and less energy spending. The aircraft dynamic responses are obtained through the runway random process modeled by Monte-Carlo method. Simulation results show that，compared with the passive control landing gears，active control landing gears can effectively improve comfort and shock absorption of the aircraft. Finally, the influence of the weighted coefficients on performance index is discussed in detail.

Key words: active control, landing gear, stochastic optimal control, statistical linearization method, flexible aircraft