Research On Guidance And Control System Of A Reentry Vehicle

A reentry maneuverable warhead with a single moving mass is taken as the research objective of the article and several key technical problems including dynamics modeling,dynamics charactertistic analysis,guidance law with deceleration control and maneuvering penetration and roll controller design are researched.The reentry vehicle is composed of the outside shell and the inside moving mass.The shape of the ouside shell is a cutting circular cone whose angle of attack is constant when the flight state is stable.By driving the internal mass along the lateral rail,the centroid of the two body system will change and the aerodynamic trim moment generated could be used to control the attitude of the vehicle.The structural and aerodynamic charactertic of the vehicle are introduced as well as the coordinates and transformation matrixs involved in the dynamics modeling.On this basis,the interation forces between the shell and the internal mass under translational and rotational motion of the two body system are derived and the nonlinear 7-DOF equations of the single moving mass reentry vehicle are presented.By being compared with modeling results of integral method and the open loop simulation,the correctness of modeling results is verified.Analysis of dynamics charactertistic is the foundation of guidance and control system design.The interation forces and moments between the shell and the internal mass are key technical problems of the moving mass control.The interation forces and moments are classified based on which the concrete forms are derived and the physical meaning and action principle are analyzed.The influence of the interation forces and moments on the attitude of the reentry vehicle and the maneuver trajectory is researched by nonlinear trajectory simulations.By linearizing the dynamics equations,the roll channel transfer function is derived based on which roll controller is designed by classical method.The tracking ability of moving mass actuator to roll angle command is verified by nonlinear trajectory simulations.Due to its unique configuration and geometry,the magnitude of the angle of attack cannot be adjusted.The internal mass is moved laterally inside the warhead body to change the center of mass of the two-body system,whereas the direction of the lift vector acts in the symmetry plane of the warhead body.Therefore,a roll moment can be produced by laterally shifting the moving mass to control the roll angle of the warhead body at a desired value.Most of commonly used guidance law can not be applied to the special vehicle studied.By introducing a new coordinate,the relative motion between the vehicle and the target is described by line of sight,error angle and the angle between the trajectory vertical plane and the error plane.The feasibility of adjusting the portion of the lift contained in the error plane and the portion perpendicular to it to achieve precision guidance is analyzed.To achieve accurate control of the error angle,a new variable is introduced based on which the transfer function from the lateral position of the internal mass to the error angle is derived.The deceleration control scheme based on adjusting the magnitude of error angle is proposed and the logic and algorithm are described.The feasibility of deceleration control is validated by nonlinear 7-DOF trajectory simulation in typical reentry mission.By establishing the penetration-interception model,analytical solutions of maneuver radius and root-mean-square of miss distance when the vehicle maneuvers in spiral form are derived.The influence of the magnitude of the error angle and the performance parameter of intercept missile on the miss distance is analyzed by nonlinear trajectory simulations.Guidance law based on error angle control can not adjust the magnitude of the error angle when the lift is not big enough in high altitude while the predictor-corrector reentry guidance law can adapt to the high altitude.However,the constraint for the computational efficiency of calculator in the vehicle is high especially when the requirement for the precision is strict,therefore,the predictor-corrector law is not suitable as the terminal guidance law.Combining strategy with practical value is put forward in this article.When the altitude of the trajectory is higher,the predictor-corrector method is adopted and the constraints of the precision in the end of the predictor-corrector part of the whole trajectory are relaxed.When the altitude is low,the guidance law based on error angle control can be adopted for the terminal guidance.The guidance perameters are optimized by the genetic algorithm,the TLC method and ADRC method are adopted to design and optimize the roll controller.