Integrated Guidance And Control Design For High Speed Aircrafts Based On Second Order Sliding Mode Method

High-speed aircraft is a typical nonlinear,fast time-varying,strong coupling system with wide spatial variation,fast speed,complex environmental factors and strong external interference during the flight.The guidance system and control system is designed independently in the traditional guidance and control design method,but the coupling between them sets the limit on the maximal performance of the aircraft.In order to improve the guidance accuracy and control stability of the aircraft,an integrated guidance and control method for high-speed vehicle is proposed in this thesis.Firstly,based on the high-speed aircraft six degrees of freedom mathematical model,an integrated model of the guidance and control is derived in this thesis.It could consider the guidance loop and control loop as a whole;obtain the control output instruction from the relative motion information of the aircraft and the target,as well as the state information of the aircraft;drive the actuator to generate the desired force and torque;and adjust the attitude and trajectory of the aircraft online.Then,based on the guidance and control integrated model,a second order sliding mode controller is proposed to deal with the relative order limit in the traditional first order sliding mode controller.It avoids thetedious steps of traditional backstepping method which require the introduction of multiple virtual controls,the design of multilayer sliding surface,the inference of the actual control law and the adjustment of multiple parameters of sliding surface.Instead,it can directly obtain the control law representation of the integrated third order model.The simulation results prove that the method improve the control precision.In addition,a second order sliding mode controller is designed based on the super twisting algorithm for the chattering problem caused by switching functions.As switching functions is included in the integral terms in the controller,it is able to guarantee the system convergence in finite time,and suppress the chattering problem effectively.At last,the disturbance observer is designed for the modeling error and the aggregation disturbance caused by the external disturbance during the integrated modeling process of high-speed aircraft.The observation value of disturbance observer is introduced into the design phase of the controller,and the aggregation disturbance is compensated when designing the control law,so as to improve the stability and robustness of the aircraft.Also the system simulation and experiment of high-speed aircraft’s terminal guidance is established to verify the feasibility and effectiveness of the proposed method.A simulation control system of terminal motion control is established based on the above three control schemes.The feasibility and effectiveness of the proposed control method is verified by the control task of attacking the maneuvering target.