AimIdentification withaMinimalParameter Set

Thispaperconsiders theproblem ofusing pas- sive(line-of-sight angle) observations ofasurface toairor anairtoairmissile (pursuer) fromanaircraft (evader), to infer whether themissile isorisnotaimedattheaircraft. Theobservations areassumed tobemadeonlyonaninitial portion ofthepursuer's trajectory. Theapproach istomodel thetrajectory ofthemissile withanumberofkinematic and guidance parameters, estimate themandusestatistical tools toinfer whether themissile isguided toward theaircraft or not.A mathematical modelispresented foramissile under pureproportional navigation withachanging velocity (direc- tion change aswellasspeed change), tointercept anonma- neuvering aircraft. A maximumlikelihood estimator (MLE) isusedforestimating themissile's motion parameters anda goodness-of-fit test isformulated totest iftheaircraft isthe aimornot.Usingmeasurement datafromseveral realistic missiles aimedatanaircraft, itisshownthat theproposed methodcansolve this problem successfully. Thekeytothe solution, inaddition tothemissile modelparametrization, is theuseofareliable global optimization algorithm forthe MLE.Theestimation/decision algorithm presented herecan beusedforanaircraft todecide, inatimely manner, whether appropriate countermeasures arenecessary. Keywordsinterceptor parameter estimation, maximumlike- lihood estimation, proportional navigation guidance, missile aimidentification, MANPADs.