Earliest Intercept Line Guidance Using a Game Theory Approach

Abstract

This paper demonstrates how the Earliest Intercept Line (EIL) can be employed to address the challenging SAM versus ASM problem where a boost-coast SAM defends a number of ships against a highly manoeuvrable supersonic sea-skimming ASM. The EIL, which is based on Dubins shortest path sub-strings, is employed to determine launch time and heading. It also determines SAM mid-course guidance manoeuvre to ensure the ships are protected. Finally the EIL helps generate a robust handover to maximise the likelihood of successful intercept. EILG is presented using a Game Theory approach in a Zerosum extensive game employing simultaneous missile moves to represent the uncertainty regarding the ASM manoeuvre. The EIL Guidance law employs a simple 3 level deferring hierarchy to determine the appropriate manoeuvre and specifically addresses the demonic non-deterministic aspect of manoeuvre uncertainty. The paper concludes with a number of examples illustrating where EILG can succeed where other missile genres might fail before suggesting the wider utility of the EIL in missile guidance. The concept of the Earliest Intercept Line (EIL) was developed to address perceived weaknesses with current missile guidance genres specifically with regard to active Surface to Air Missiles (SAM) which employ constrained data update rates during the mid-course phase due to sensor limitations. The goal was to help improve missile to missile single shot kill probability. As the concept has been developed it has become clear that the EIL could have wider utility to augment current guidance genres across a wide range of applications. This paper expands considerably the results described in, 1 , 23 on how the EIL can be used to address the complete engagement process. As the EIL concept is not well known, this paper will initially summarise the results of, 1 , 2 , 3 then explain the approach and terminology before addressing EIL guidance as a complete process. This is to obviate as much as possible any need to refer back to these papers except on matters of detail. The paper also includes a description of the specific problem being addressed which has been termed the SAM versus ASM (SvA) problem, as well as what an EIL is, how it can be generated, what information it provides and how it can be used in an AAW scenario. The new results will focus on addressing the SvA problem using a simple Game theory approach showing how the EIL can be used as a control mechanism in 3 phases, pre-launch, mid-course and then robust-handover to terminal guidance to enhance the probability of success. After describing each aspect, the paper will provide appropriate illustrations, from simple MATLAB simulations,