Meeting the challenges of modern interceptor guidance by non-conventional approaches
The challenge of intercepting threats with non conventional warheads, the major drive for the development of ballistic missile defense systems since the first Gulf War of 1991, became even more serious when the reentry vehicles were assumed to be capable of maneuvering. Successful interception of such targets, requiring very small miss distances, cannot be guaranteed by the classical guidance and estimation methods that have been used against manned aircraft. Future interceptor guidance strategy has to be based on pursuit-evasion game concepts and the estimator design has to be integrated with the guidance law. Following such non conventional approaches has the potential to achieve the requirement of hit-to-kill accuracy against randomly maneuvering threats.
Time-Varying Linear Pursuit-Evasion Game Models with Bounded Controls
Future end game interception scenarios of autonomous uncrewed e ying vehicles are expected to be characterized by variable velocities and lateral acceleration limits. A time-varying linear pursuit ‐evasion game model with bounded controls is presented that can be used to analyze such scenarios. The usefulness of this model is demonstrated by simulations of a realistic ballistic missile defense scenario, as an example. It is shown that a differential game guidance law derived using this time-varying model provides a signie cant improvement in the homing accuracy compared to a guidance law based on a model with constant velocities and lateral acceleration limits. Moreover, the time-varying linear model provides a much more accurate prediction of the miss distance, cone rming its validity. Also a general review of possible structures of the game space decomposition is presented. Oneofthese structuresimpliesthateven ifthepursuerdoesnot havea maneuverability advantage overtheevader, but has an agility advantage, a zero miss distance can still be achieved for some initial conditions.
New Interceptor Guidance Law Integrating Time-Varying and Estimation-Delay Models
The paper presents a synthesis of a new guidance law, derived using differential games concepts, for the interception of highly maneuvering targets. The synthesis is based on the integration of two recently demonstrated improvementfeatures:namely,theuseofa time-varying linearkinematicsgamemodelandthecompensationofthe inherent estimation delay of thetarget acceleration. The new guidance law is implemented in a genericyet realistic noise-corruptedthree-dimensionalnonlinearballisticmissiledefensescenariobyusingasuitablethree-dimensional estimator.Thetestagainstworst-casetargetmaneuversdemonstratesasignie cantimprovementcomparedto other known guidance laws indicating a potential breakthrough in interceptor guidance. I. Introduction H ISTORICALLY, the typical target of interceptor missiles has been a manned aircraft, against which the missile had substantial advantage in speed, maneuverability, and agility. Moreover, miss distances of a few meters, compatible with the lethal radius of the missile warhead, were considered admissible. Because of these facts, even a simple guidance law such as proportional navigation (PN) could guarantee the target destruction. The Gulf War introduced the tactical ballistic missile (TBM), able to carry nonconventional warheads, as a new type of target. Successful interception of a TBM, much less vulnerable than an aircraft, requires a very small miss distance or even a direct hit. Several ballistic missile defense systems are currently in development. Because of advances in technology, these systems (such as ARROW and PAC-3) succeeded to demonstrate, using conventionalguidance concepts, excellent homing accuracy against such nonmaneuvering targets. 1;2 Although known TBMs were not designed to maneuver because of their high reentry speed, they have a substantial maneuverability potential in the atmosphere. Moreover, this potential can be made applicable by a modest technical effort. The same is true for future high-speed antiship or cruise missiles.Paradoxically, the successful current development of ballistic missile defense systems can serve to motivate the future development of maneuverable antisurface missiles. Against such threats interceptor missiles will have only a marginal maneuverability advantage. Hence, the required small miss distances are not achievable by using conventional guidance laws even in a noise-free environment, as it was demonstrated by recent simulation studies. 3;4 Most missile guidance laws used at the present, including PN, were derived using a linear quadratic optimal control formulation assuming perfect information. 5 Such a formulation requires an assumption on the future evolution of the target maneuver. If this