Research On Feature Aided Highly Maneuvering Target Interception

With the development of aviation and homing guidance,precision interception for the highly maneuvering targets gradually becomes a pressing need in many applications.Combining with some relative application backgrounds,this thesis aims to the deficiencies in existing guidance system design techniques for highly maneuvering target interception,and focuses main attention on the terminal guidance phase determining the guidance precision.By means of integrating radar target scattering signatures in the terminal guidance,this research studies fast realtime target motion mode identification based on radar signatures,feature aided state estimation and mix guidance law.The ultimate goal is to improve the guidance loop response speed to the target maneuver and acquire a suboptimal interception performance when the Certainty Equivalence Principle is untenable.By this means,the need of precision interception for highly maneuvering target with aforementioned backgrounds could be met.Chapter 1 firstly analyzes the significance of highly maneuvering targets interception.Some problems in existing guidance system are concluded.Then,based on the Separation Theorem,a comprehensive and up-to-date survey of the methods of estimator and guidance law design in terminal guidance is presented.Aiming to the major difficulties in current studies,we point out our thoughts and solutions,and give the organization of this thesis at last.Chapter 2 studies the performance evaluation of feature aided terminal guidance system.A mathematical model of feature aided terminal guidance system is presented firstly.Then the basic definition and physical meaning of observability analysis are introduced in detail.Combining with the application characteristics,a rationality analysis of existing observability analysis method and its deficiencies are presented.On this basis,a novel singular value decomposition observability analysis method of feature aided terminal guidance system is proposed.With a comprehensive consideration of observability matrix eigenvalue,the highest orders of measurement derivative and the state magnitude,the proposed method clearly shows which state or states combination observability is enhanced by integrating target features.It supplies a theory basis for the study on signature selection and target acceleration estimation in the following chapters.Chapter 3 studies the relationship between the relative orientation of missile-to-target and motion modes.From the perspective of relationship between the sensor coordinate system and the target body coordinate system,a basic model of sensor is stated and the definition of relative angular velocity between the two coordinate systems is introduced firstly.Then,the three dimensional analytic expressions of relative angular velocity for different motion modes are derived and simplified by analyzing the influences of target centroid motion,rotation around centroid and relative motion.Finally,the relationships of the relative angular velocity directions and values with motion modes are discussed.It is demonstrated that there are significant differences of the relative orientation in different motion modes.It provides theory guidelines for feature aided maneuver detection and maneuver direction discrimination which would bring a great improvement for interception performance.Chapter 4 studies maneuver information extraction from the pose sensitive radar signatures.Considering the planar interception against a skid-to-turn aerocraft as the scenario,firstly,the relationship between the slope of inverse synthetic aperture radar(ISAR)image and maneuver direction is derived.Then,the principle of maneuver direction discrimination using the ISAR images is fully explored.Secondly,the discriminator parameters selection and some important factors affecting the discrimination performance are discussed comprehensively.A novel and practical discriminator is developed with a rigorous analysis of the scenario characteristics afterward.Finally,the simulation confirms the rationality of the design procedure and makes a detailed statistical analysis of discrimination performance.Both the computer simulation and anechoic chamber measurement results demonstrate that the proposed discriminator performs better than the classical innovation-based maneuver discriminator in discrimination probability and delay.Chapter 5 studies the feature aided design of estimator and guidance law.Firstly,a comprehensive algorithm comparison and performance evaluation of estimators which are widely used in highly maneuvering target interception is presented.The merits and drawbacks,applicable conditions of different estimators are discussed.Then,a variable structure multiple model estimator integrated maneuver direction signature feature is proposed.Secondly,from the perspective of differential game solution and capture zone,a depth analysis on importance of maneuver direction discrimination and discrimination delay reduction for guidance law design is introduced.It is demonstrated by simulation that the interception performance is significantly improved after integrating the target maneuver direction information in guidance law design.Finally,according to the characteristics of different combinations of single estimator and guidance law,an integrated estimation and guidance design approach with target maneuver direction discrimination is proposed.The results show that integrating target maneuver direction would fully improves the highly maneuvering target interception performance both in estimation and guidance.Chapter 6 summarizes the results and conclusions of the thesis and points out the possible future work.