Ground target tracking with variable structure IMM estimator

In this paper we present the design of a Variable Structure Interacting Mul tiple Model (VS-IMM) estimator for tracking groups of ground targets on con strained paths using Moving Target Indicator (MTI) reports obtained from an airborne sensor. The targets are moving along a highway, with varying obsc uration due to changing terrain conditions. In addition, the roads can bran ch, merge or cross-the scenario represents target convoys along a realistic road network with junctions, changing terrains, etc Some of the targets ma y also move in an open field. This constrained motion estimation problem is handled using an IMM estimator with varying mode sets depending on the top ography. The number of models in the IMM estimator, their types and their p arameters are modified adaptively, in real-time, based on the estimated pos ition of the target and the corresponding road/visibility conditions. This topography-based variable structure mechanism eliminates the need for carry ing all the possible models throughout the entire tracking period as in the standard IMM I estimator, significantly improving performance and reducing computational load. Data association is handled using an assignment algori thm. The estimator is designed to handle a very large number of ground targ ets simultaneously A simulated scenario consisting of over one hundred targ ets is used to illustrate the selection of design parameters and the operat ion of the tracker. Performance measures are presented to contrast the bene fits of the VS-IMM estimator over the Kalman filter and the standard IMM es timator. The VS-IMM estimator is then combined with multidimensional assign ment to gain "time-depth." The additional benefit of using higher dimension al assignment algorithms for data association is also evaluated.