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Performance evaluation of multisensor track-to-track fusion

Track-to-track fusion is an important part in multisensor fusion. In practice, the process noise is not negligible due to target manoeuvring and sensors typically communicate infrequently to save communication bandwidth. In such situations, the measurements from two sensors are not conditionally independent due to the common process noise from the underlying system. This dependence phenomena was also observed by Bar-Shalom (1981) where a formula was derived to compute the cross-covariance of two track estimates obtained by different sensors. Based on the results, a fusion formula was subsequently derived (Bar-Shalom et al. (1986)) to combine the local estimates which took into account the dependency between the two estimates. This paper points out the implicit approximation made by Bar-Shalom et al. and shows that the result turns out to be optimal only in the maximum likelihood sense. A performance evaluation technique is then proposed to study the performance of various track-to-track fusion techniques. The results provide performance bounds of different techniques under various operating conditions which can be used in designing a fusion system.