Research On Trajectory Characteristics And Flight Control Law Of Hyper Velocity Two Dimensional Trajectory Correction Projectile

Hyper Velocity Two Demensional Trajectory Correction Projectile(HVP)has been valued by many countries because of its fast flying speed and long range.But the uncertainty of its model and random disturbance makes guidance and flight control difficult.In this paper,the relevant guidance and flight control methods are studied for HVP which has been published abroad.In order to study the ballistic characteristics of HVP,a nonlinear spatial motion model of six-degree rigid-body is established according to its aerodynamic shape characteristics and and the trajectory is numerically simulated.And small disturbance linearization is carried out on the basis of nonlinear trajectory model.The coupling transfer functions of pitch channel and yaw channel are derived in the complex domain,and feed forward compensation method is used to decouple the system,the free motion of angle of attack under step disturbance and the flight dynamic stability is analyzed.A method of Impact Point Prediction(IPP)is proposed which combine the Extended Kalman Filtering(EKF)and the sensitivity Matrix to increase the guidance precision of projectile.Firstly,the three-degree-of-freedom mass point projectile model is employed,the discrete state equation of Kalman filtering and satellite measurement equation are deduced.Secondly,EKF filter is used to predict a disturbance trajectory,and a guidance law based on sensitivity matrix is designed according to the impact point.Finally,the guidance law is simulated and verified.The results shows that EKF can predict the impact point quickly,and the sensitivity matrix guidance law can decreace the Circular Error Probable(CEP)effectively.In order to realize the command tracking control of angular motion,the corresponding control laws are designed for linear and nonlinear angular motion systems respectively.Firstly,a linear PID controller is designed on the basis of decoupling of the linear system,and the robustness of the PID controller under the condition of time-varying model system and external interference is studied by simulation.The results show that the PID controller has poor robustness.Therefore,fuzzy control theory was introduced,and the Mamdani controller was designed for the angle of attack control system,and the simulation analysis was carried out.The results show that the fuzzy controller can overcome the influence of time-varying model and external disturbance positively,the robustness is strong.Secondly,the model of nonlinear angular motion system has been deduced.Introduced the differential geometry theory and Sliding mode variable structure control theory.Firstly,a control law is designed based on linearized feedback theory;Secondly,a compound control law is designed which conbine with linearized feedback theory and sliding mode theory,then use saturation function instead of sign function.Finally,two kinds of control laws are simulated respectively.The results show that the feedback linearization control decouples the nonlinear system,but cannot overcome the external disturbance,and its robustness is poor.While the sliding mode variable structure control law based on feedback linearization has great anti-interference and strong robustness.The high frequency chattering phenomenon of sliding mode control output signal is effectively reduced by using saturation function instead of symbol function.