Tracking evasive move-stop-move targets with arm MTI radar using a VS-IMM estimator

In this paper we present the design of a Variable Structure Interacting Multiple Model (VS-IMM) estimator for tracking evasive ground targets using Moving Target Indicator reports obtained from an airborne sensor. In order to avoid detection by the Mrl? sensor, the targets use a "move-stop-move" strategy, where a target deliberately stops or moves at a very low speed for some time before accelerating again. In this case, when the target's radial velocity (along the line of sight from the sensor) falls below a certain Minimum Detectable Velocity, the target is not detected by the sensor. Under these conditions, the use of an estimator, which does not take care of this "move-stop-move" motion explicitly, can result in broken tracks. The tracker proposed in this paper handles the evasive "move-stop-move" motion via the VS-IMM estimator, where the tracker mode set is augmented with a "stopped-target" model when the estimated speed of the target falls below a certain threshold. Using this additional "stopped-target" model, the target state is kept "alive" even in the absence of a measurement. A simulated scenario is used to illustrate the selection of design parameters and the operation of the tracker. Performance measures are presented to contrast the benefits of the VS-LMM estimator, which uses the "stopped-target" model, over a standard IMM estimator.