A Box Particle Filter Method for Tracking Multiple Extended Objects

Extended objects generate a variable number of multiple measurements. In contrast with point targets, extended objects are characterized with their size or volume, and orientation. Multiple object tracking is a notoriously challenging problem due to complexities caused by data association. This paper develops a box particle filter method for multiple extended object tracking, and for the first time it is shown how interval based approaches can deal efficiently with data association problems and reduce the computational complexity of the data association. The box particle filter relies on the concept of a box particle. A box particle represents a random sample and occupies a controllable rectangular region of non-zero volume in the object state space. A theoretical proof of the generalized likelihood of the box particle filter for multiple extended objects is given based on a binomial expansion. Next the performance of the box particle filter is evaluated using a challenging experiment with the appearance and disappearance of objects within the area of interest, with real laser rangefinder data. The box particle filter is compared with a state-of-the-art particle filter with point particles. Accurate and robust estimates are obtained with the box particle filter, both for the kinematic states and extent parameters, with significant reductions in computational complexity. The box particle filter reduction of computational time is at least 32% compared with the particle filter working with point particles for the experiment presented. Another advantage of the box particle filter is its robustness to initialization uncertainty.