Research On Multi-constrainted Terminal Guidance Laws And Target State Estimation Methods

According to the demand of missile detection and guidance technology,this paper mainly stuidies on advanced multi-constrainted guidance laws and target state estimation problems of passive bearing-only missiles.Firstly,the paper introduces the status and trend of multi-constrainted guidance laws including time control and angle control.The development technology of target estimation by single passive bearing-only missile and by multiple passive missiles is also summarized.Impact time control guidance laws are proposed considering different constraints such as filed-of-view(FOV),time-to-go and missile-missile communication.A new impact time control guidance law is devised based on the trajectory polynomial function.The optional scope of cooperative guidance time can be calculated by considering the limits of missile maneuvering acceleration and seeker’s FOV angle.To avoid the time-to-go estimation error effect on cooperative guidance accuracy,impact time control problem is transformed to look angle command tracking problem.The look angle command guarantees both flight time and FOV constraints.As considering the real time communication between missiles,another cooperative guidance law without time-to-go information is proposed based on multi-agent second order consistency theory to control missile-target distances and look angles of each missile.Analytical solutions of proportional navigation guidance(PNG),trajectory shaping guidance(TSG)and BPN guidance law are derived respectively.Impact angle control guidance laws based on biased proportional navigation(BPN)are stuided.Stability region of BPN is given by the phase plane trajectory curve.Analysis results also show the trajectory characteristic with different bias action time.Based on this,further study considers FOV limts in BPN guidance law.According to the relations between look angle and command bias,the time-varying bias is proposed to satisfy both impact angle constraint and seeker’s FOV limit.Results show that BPN is the normal form of PNG and TSG.Compared to TSG,the proposed guidance law BPN can choose different bias action time according to different tasks.Furthermore,BPN does not need time-to-go information and has easy form to use flexibly.Two multi-constrainted guidance laws are compared for both impact time and angle control.Firstly,an imapct time control guidance law is used to reduce the time-to-go error.Once the impact time error becomes smaller than the tolerance parameters,guidance law switches to the impact angle control guidance law.Another impact time and angle control guidance method establishes the relations between terminal angle and line-of-sight(LOS)angle.Then sliding mode surface is designed to track the desired LOS rate and desired time-to-go.Research shows that both two guidance methods can achieve terminal angle and flight time constraints.Compared to the switching method,the later sliding mode guidance law has higher control accuracy.Target states of passive bearing-only missile are established in cartesian coordinate system,polar coordinated system,and modified polar coordinate system respectively.Range-parameterised filter method is introduced to minimize the effect of Kalman filter initial distance error.The target observability when attacking stationary target and moving target is studied,and then analyze the target observability under different guidance laws such as PNG,TSG and BPN.Simulation results show that the convergence speed of three coordinate target states models is slow.The convergence speed and estimation accuracy can be improved significantly by using range-parameterised filter.The target observability mainly depends on navigation coefficients and initial parameters.Compared with PNG,TSG and BPN control trajectory to adapt terminal angle,these two guidance laws are able to guarantee target observability.Cooperative target state estimation problems with multiple passive bearing-only missiles are studied in two-dimensional plane and three-dimensional space respectively.By establishing the cooperative estimation model,target loaction can be estimated by missile-missile-target kinimatic relations.Interacting multiple model Kalman filter is introduced to track the non-constant maneuvering target.This paper also does reasearch on the maneuvering target cooperative estimation in three-dimensional space by estabilshing the mathematics model between two bearing-only missiles and one target.Research shows that cooperative estimation can improve the target observability dramatically and estimate guidance information such as missile-target distance,LOS rate and target acceleration quickly and accurately.