IMM estimators with unbiased mixing for tracking targets performing coordinated turns

The tracking of highly maneuvering targets using an interacting multiple model (IMM) estimator is considered. Two IMM estimators are evaluated: one which incorporates a horizontal coordinated turn model and one which incorporates a 3D coordinated turn model. An objective comparison of the track performances achievable with the two IMM estimators is given in the paper. Since the models in each IMM have different state dimensions, special care must be taken during the mixing stage to prevent biases. Previously, an unbiased mixing procedure was developed for an IMM estimator with two modes, and this work extends the previous result to an IMM estimator with three modes. Performance assessment of the IMM estimators was performed using a high fidelity radar simulation and benchmark scenarios. Results show that both IMM estimators provide performance enhancements over the default solution during horizontal turns. However, the IMM estimator that incorporates a 3D coordinated turn model performed better during vertical maneuvers.