Research On The Method Of Exterior Ballistic Control Of Electromagnetic Launch Guided Munitions

Electromagnetic launch guided munition is a kind of hyper-velocity projectile(HVP)suitable for electromagnetic railgun(EMRG).Its external ballistic process is a nonlinear time-varying system.In this paper,reasonable simplifications and assumptions are used to consider the external ballistic flight process of electromagnetic-launched munitions in sections,respectively,and carry out research on related external ballistic issues such as roll stability analysis,ballistic optimization and control system design.This paper proposes a flight transition strategy of active spin-up,high-speed roll,de-spinning and anti-swing,which can effectively solve the flight stability problem because of excessive initial velocity and high dynamic pressure at the muzzle.Combining the theory of the dynamic stability of the rotating projectile and the steering gear hinge torque limit,reasonable preset rudder deflection angle,roll angle rate limit,roll stability area,and control timing of anti-rotation and anti-sway control suitable for electromagnetic launching guided munitions are obtained through theoretical derivation and simulation analysis.In order to achieve precise strikes and effective damage to long-range fixed targets by electromagnetic launch guided munitions,this paper proposes a segmented trajectory optimization design method with the maximum dynamic pressure limit as the segmented node,which can obtain the optimal trajectory of the projectile during the rotating flight phase and the active control phase respectively.During the rotating flight phase,electromagnetic launch guided munitions fly freely according to the parabolic trajectory,without considering the changes in aerodynamic parameters caused by the flight attitude and rolling motion.During the active control stage,this paper discretizes the optimal control problem of the nonlinear system to obtain a nonlinear programming problem by hp adaptive pseudospectrum method,and designs for boundary conditions,state variables,control variables,path constraints and performance indicators,and obtains the trajectory optimization program against a fixed target in shortest time.Aiming at the active control stage of electromagnetic launch guided munitions,this paper adopts linearization method to obtain the longitudinal short-period linear time-invariant model at the working point of the ballistic characteristic,and further designs the pitch channel two-loop overload autopilot and the traditional gain scheduling controller,which basically meets the requirements of stable control and smooth switching requirements in large airspace and wide speed range.The traditional two-loop autopilot and the two-loop overload autopilot with PI correction designed for the characteristic operating point of the pitch channel can meet the expected control effect through simulation verification,but there are certain limitations.Furthermore,in order to enable the gain parameters of the two-loop overload autopilot with PI correction to be smoothly switched according to the changes of the flight status,this paper takes the flight height and flight speed as the scheduling variables,and designs the traditional gain scheduling controller and gives its gain schedule within a certain range.Finally,the MATLAB/simulink platform simulation verifies the control effect and interference suppression ability of the designed gain scheduling controller.In summary,this article is aimed at the external ballistic process of electromagnetic launch guided munitions,based on reasonable simplification and segmentation assumptions,and basically solves related key and difficult issues such as rolling flight stability,segmented trajectory optimization,and control system design.The research provided a certain reference and promoted the engineering application process of electromagnetic launch guided munitions.