Study on cooperative missile guidance for area air defence

Abstract

This research investigates the necessary components to design cooperative guidance strategies for area air defense applications, as a part of a project supported by UK MoD and French DGA MCM-ITP (Materials and Components for Missile - Innovation and Technology Partnership) programme. The main considerations in developing the cooperative guidance scheme are the uncertainty of the target manoeuvre and the zone defence concept. For the interception of unpredictable targets before they reach any asset in the defended area, Earliest Intercept Geometry (EIG) and Intercept Geometry (IG) are introduced; EIG is analytically obtained and IG is numerically computed in consideration of physical constraints of the missile and target. Then, two mid course guidance laws are proposed using the geometries, termed the Earliest Intercept Geometry Guidance Law (EIGGL) and Intercept Geometry Guidance Law (IGGL). Since the EIG or IG represents a capture zone of the missile, the defended assets can be protected if the guidance law guarantees no overlapping between the geometry (EIG or IG) and the defended area. In many-on-many engagement scenarios, it is clear that the performance of the guidance scheme depends on the target allocation policy, thus an optimal target allocation algorithm is designed using the EIG and IG to maximize the reachability and safety margin. Multiple co-existing hypotheses about future target trajectory in the mid course and homing phase result in an initial angular di erence between actual flight path and the flight path demanded by the homing guidance law at handover, termed the heading error. Even if a hypothesis of future target trajectory is common to mid course and homing guidance laws, heading error can be caused by errors in uplink data because of radar/launcher misalignment, tracker lag, radar measurement error etc. Since this error might result in an abrupt change of the missile acceleration, it is undesirable. In order to resolve this problem, an optimal homing guidance law is developed by introducing a second order polynomial function into the cost function of the guidance problem. The performance of the optimal guidance law heavily depends on the accuracy of the time-to-go estimates. Because the optimal guidance laws are used in the calculation of the IG and the terminal homing guidance, a time-togo estimation algorithm is also proposed. The performance of each algorithm is demonstrated using simple numerical examples. Furthermore, the overall performance of the cooperative guidance algorithm is verified using scenarios in naval and ground context and a Simulink Common Model (CM). For the algorithm test and development, these scenarios and CM have been shared between partners and have evolved during the project. Future work within this research area is discussed further in the last chapter of this thesis, along with other applications for the cooperative guidance scheme ii