Cooperative Guidance On Aircraft Terminal Active Protection

Aircraft are vulnerable targets of missiles during air combat.Compared with the traditional passive countermeasures such as infrared decoys,active defense tactic is a more effective way to protect the aircraft.This essay conducted researches on the target-missile-defender three-body problems,including the detection of the incoming missile,the guidance law of the defensive missile,and the maneuver schemes of the aircraft.The main work includes:(1)A multi-model and multi-sensor data fusion tracking and estimation method was proposed to address the problem of the detection of incoming missiles.The kine-matics model and sensor measurement model of the three-body conflict problem are an-alyzed,and the optimal state estimation of complex maneuvering targets is achieved by using the interactive multi-model method combined with nonlinear filtering.Two fusion estimation methods are proposed on the radar and infrared sensor,including a centralized and a distributed method.Aiming at the maneuver estimation problem of the incoming missile,the interactive multi-model method was used to identify the guidance law of the incoming missile.(2)In order to design the defensive missile's guidance law,the optimal prediction guidance law is proposed for three performance indexes: the time-optimal,energy-optimal,and linear zero-effort-miss.The three-body conflict kinematics model and prediction model are established in the plane frame.Three optimal methods for solving the time-to-go information are proposed,and thus three corresponding prediction guidance laws are obtained.The numerical solution is used to efficiently and quickly obtain the optimal solution.Numerical simulations verify that the proposed predictive guidance laws have a small amount of calculation and guidance commands are generated quickly,which meets the performance requirements of modern on-board computers.(3)A three-dimensional virtual target-based predictive guidance law is proposed to address the problem of uncertain factors.Combining iterative calculations with classic guidance laws,a real-time prediction method on the interception point is pro-posed,and the predicted point is used as a virtual target.The speed of the virtual target is estimated by the Kalman filter.Then the defender is guided to the virtual target.There-fore,the problem of intercepting a high-speed missile is transformed into the problem of intercepting a low-speed virtual target,which simplifies the guidance difficulty and improves the interception performance.Numerical simulation proves that the proposed method is robust to unknown guidance law targets and nonlinear disturbances.(4)A cooperative maneuvering strategy of the aircraft is proposed.Two strate-gies including the three-point maneuver and the minimum effort cooperative maneuver are proposed,which make the aircraft not only ensure self-survival,but also help the defense missile to better complete the guidance and interception task.The maneuvering enve-lope that can guarantee the successful interception of defensive missiles is solved,and the optimal maneuver with the minimum guidance energy is calculated in the maneuvering envelope.(5)The optimal launching strategy of the defensive missile is proposed.A guid-ance model with launch time as the control input is established.The launch time window is calculated which guarantees the successful interception,and the optimal launching time is solved by optimization.Based on the predictive guidance law proposed in this paper,the optimal launching situation that can minimize the guidance effort is derived.The optimal launching time is obtained by optimizing the predictive heading deviation angle.