Variable Structure Interacting Multiple Model Filter (VS-IMM) for tracking targets with transportation network constraints

A Ground Moving Target Indicator (GMTI) is developed using a Variable Structure Interacting Multiple Model Filter (VS-IMM). Current trackers use road network database information to either condition GMTI measurements, thereby altering the detection report, or constrain tracks formed on measurements near roads to the road network, thus making a hard decision about the location of the target. The VS-IMM allows for soft decisions about which road a target is possibly located on. The VS-IMM filter developed adaptively adds and deletes road models based upon history of measurement data or extrapolated tracks. As measurements are associated with existing tracks, a search of possible road segment models is performed to either add or delete road segment models as required. As targets on roads approach junctions, additional potential road segment models are added, as the targets pass the intersection only the most likely model is retained. When a target begins to move into a road segment that is obscured, a model is added that modifies the filter estimate and likelihood according to a hidden target model. The VS-IMM Filter includes two models for characterizing temporal vehicle movement. A model with low process noise is used to model targets that are traveling straight and a model with high process noise is used to model highly maneuvering targets. The state estimates from the possible road models are combined with the state estimate of the on-road and off-road multiple temporal models to produce the composite state estimate for the VS-IMM Filter.