Research On The Time Delay Control System Based On Magnetorheological Shimmy Damper

Nose landing gear shimmy of aircraft is a kind of harmful self-excited vibration during take-off or landing,its front wheel or main wheel will sometimes have a violent swing away from the neutral position,which is a kind of wheel swing,accompanied by the fuselage movement and tire deformation.Shimmy exists widely in various types of aircraft,such as civil aircraft,military aircraft and unmanned aerial vehicle.Magnetorheological shimmy damper has many advantages such as wide range and controllable damping force,therefore,it is expected to achieve better shimmy suppression effect and make up for the deficiency of the current method.There is a response time delay in the aircraft nose landing gear shimmy damping system based on magnetorheological damper.The ideal damping force output by the controller can act on the landing gear shimmy motion only after a period of time delay,which will decrease the system’s effect of shimmy suppression.In order to design a control system which can ensure the stability of the nose landing gear shimmy damping system under different time delay conditions,the following aspects are studied in this paper.Firstly,based on the design parameters of landing gear of a light UAV and the dynamic experimental data of MR shimmy damper,the dynamical model of nose landing gear of aircraft was established,and the dynamical model of MR shimmy damper Bouc-Wen was identified.In the process of identification,the identification algorithm is improved to improve the identification efficiency.Secondly,the reasons and the value of the time delay in the aircraft nose landing gear shimmy damper system based on magnetorheological damper are analyzed.The electromagnetic response time delay of the magnetorheological damper is simulated.This paper presents a research idea that the nose landing gear shimmy suppression system is considered as a whole target,and the real-time total time delay estimation based on the measured current and the shimmy motion state of the landing gear.An online time delay identification system for magnetorheological shimmy suppression system was established by using firefly algorithm and BP neural network,and the accuracy of identification results was proved by verification.Thirdly,on the basis of modeling and time delay analysis,the control algorithm for stabilizing the system is calculated using the backstepping method.And the adaptive function is designed,and the adaptive control system is realized by using the adjustment adaptive function of online identificated time-delay.The control system can maintain stability under different time delay conditions and obtain good effect of shimmy control.Finally,the influence factors of the nose landing gear shimmy motion are analyzed by simulation.The control effectiveness and time-delay stability of the adaptive control system are verified by simulation.