Pursuer Aim Identification for Evaders Using Bearing-only Measurements

Abstract

Identifying the aim of the pursuer accurately and timely is vital for evader taking appropriate countermeasures to avoid capture successfully. In order to determine whether the evader in a flying formation is aimed by the pursuer or not, an aim identification algorithm is proposed based on the stationarity difference of the mixed product of three direction vectors, i.e., the evader's velocity vector and the evader-to-pursuer line of sight (LOS) vector at the same instant as well as another such LOS vector at a subsequent instant. Due to the effect of the guidance law, the subsequent LOS always shows a tendency to keep coplanar with the velocity of the aim and the previous LOS such that the mixed product obtained by the aim changes very slowly. In another word, the mixed product sequence obtained by the aim based on the known velocity and the bearing measurements of the LOS has relatively good stationarity while the stationarity of the sequence obtained by the evader not being aimed at is poor. Based on the stationarity difference, the mixed product sequences are used to formulate a chi-square distributed statistic such that the aim identification is equivalently transformed into a hypothesis testing problem. Simulation results are given to verify the effectiveness of the proposed algorithm.