On-line Trajectory Planning Based On Parameter Identification For Boost-glide Missile

Boost-glide missile has the advantages of rapid arrival,long range and wide range of maneuverability.It is an effective weapon to realize long range and quick response and strike timely targets.In order to overcome uncertainty of the flight environment and the vehicle’s parameter,improve the missile ability of accomplishing diversified task,this paper,aim to realize the online trajectory planning based on parameter identification,studied the missile’s propulsion system parameter identification problems during flight,high reliability calculating atmospheric parameters and aerodynamic parameter identification problems,the online trajectory planning problems for boost phase and glide phase.This paper analyzes the influence of various parameter deviations on the flight performance of the boost-glide missile during flight,considers the current development level of on-board sensors,summarizes which parameters are worth identifying and which parameters can be identified,and determines the scheme of identifying: propulsion system parameter in the boost phase and aerodynamic parameters in the glide phase.The simulation also shows that the glide trajectory mainly depends on lift-drag ratio.Since lift-drag ratio is not a constant value,this conclusion is generalized as relationship function between the lift-drag coefficients and used in the parameter identification and trajectory planning of gliding phase.Based on theinternal ballistics model of solid rocket motor and attitude dynamic model of boost rocket,the basic on-line identification method of engine parameters is established.According to the dynamic pressure,the identification strategy is discussed in two specific cases.In the small dynamic pressure phase,the thrust line deviation,vacuum specific impulse,mass and second consumption can be identified and the remaining combustion time can be estimated according to the pre-established mass model and the on-line measured apparent acceleration,attitude angular velocity,combustion chamber pressure and other information.In the high dynamic pressure phase,the angle of attack needs to be measured.Aiming at the identification of aerodynamic coefficients in the glide section,the dependence on Angle of attack was reduced by expressing the drag coefficient as a function of lift coefficient and Mach number,and relevant entries were identified by the recursive least square method.Deviation analysis shows that this model is closely related to the flight trajectory,and online trajectory planning can be directly based on this model.In this paper,a simplified three-degree-of-freedom model based on local parameters is proposed to solve the online trajectory planning problem in the boost phase.By convexifying the equation,the original problem can be approximated by a series of convex subproblems.For gliding section of the online trajectory planning problem,considering the highly nonlinear dynamic model and constraints,this paper refined the primary dynamic model by using trajectory arc length as independent variable and logarithmic velocity instead of speed as the state variable.The model greatly simplifies the dynamic equation with little loss of accuracy and reduces the nonlinear property obviously.Furthermore,the main dynamic pressure and heat flow constraints become linear constraints,which greatly reduce the difficulty of solving the whole problem.On this basis,the sequence of convex subproblems approximating the original problem is constructed by means of relaxation techniques,so that the problem can be solved efficiently by sequential convex optimization method.The work done in this paper can provide reference for online estimation of aircraft propulsion system parameters and atmospheric aerodynamic parameters,and provide technical support for online trajectory planning,online mission planning,overall and trajectory optimization of spacecraft.