Research On Optimal Terminal Guidance Law For Guided Projectile Under Multi-constraints

Modern warfare puts forward higher requirements for guided projectiles.In order to meet the damage efficiency of different targets,it is necessary to meet the dual requirements of landing accuracy and corner constraint.However,due to the overload restriction of the guided projectile itself,the measurement angle restriction of the sight angle of the seeker,the angle of attack restriction,lag,interference,mismatch of the control and guidance system and other reasons,it is difficult to achieve the guidance accuracy of the guided projectile.In this paper,optimal control theory and sliding mode variable structure control theory are used to solve the terminal guidance problem of guided projectiles under multiple constraints.Firstly,the motion model of guided projectile and target and the relative motion model of projectile and target are established.Then,the relative model of projectile and target is linearized under the hypothesis of small angle.The consistency between the linearized model and the guidance effect derived from the non-linearized model is verified by simulation,and the feasibility of linearization of the model is proved.Secondly,biased proportional terminal guidance law and optimal terminal guidance law with angle-of-attack constraints are designed respectively,and simulation results show that the optimal terminal guidance law not only has better guidance effect but also has the best process energy.To improve guidance stability,two kinds of terminal guidance models with angle-of-attack and angle-of-attack constraints with dynamic lag are designed,and the optimal control theory is used to obtain the optimal guidance law by trajectory shaping method.The optimal terminal guidance equation is constructed by designing the distance-weighted optimal performance index to solve the constraint problem of the angle of sight of the seeker.The variable weight method and the switching function method are used to realize the constraint of the angle of sight and overload of the seeker,and the simulation results verify the constraint effect.In addition,the operation caused by the seeker is verified.The influence of dynamic lag on guidance accuracy.Thirdly,in order to improve the robustness of the optimal terminal guidance law,the optimal sliding mode terminal guidance law is designed based on the sliding mode variable structure control theory.The trajectory angular rate is calculated according to the optimal control theory,and the sliding mode surface of the trajectory angular rate is designed by using the approach law.The simulation results show that the optimal sliding mode terminal guidance law can enhance the terminal guidance under white noise interference and targetmaneuver effect.Finally,in order to achieve the perfect coordination between control and guidance system,the integrated model of control and guidance with angle of attack and angle of fall constraints in second-order dynamics is designed.The solution of integrated control and guidance is obtained by optimal control theory and trajectory shaping solution method,and the feasibility and stability of integrated control and guidance are verified by simulation.