In the battlefield surveillance domain, ground target tracking is used to evaluate the threat. Data used for
tracking is given by a Ground Moving Target Indicator (GMTI) sensor which only detects moving targets.
Multiple target tracking has been widely studied but most of the algorithms have weaknesses when targets are
close together, as they are in a convoy. In this work, we propose a filtering approach for convoys in the midst of
civilian traffic. Inspired by particle filtering, our specific algorithm cannot be applied to all the targets because of
its complexity. That is why well discriminated targets are tracked using an Interacting Multiple Model-Multiple
Hypothesis Tracking (IMM-MHT), whereas the convoy targets are tracked with a specific particle filter. We
make the assumption that the convoy is detected (position and number of targets). Our approach is based on an
Independent Partition Particle Filter (IPPF) incorporating constraint-regions. The originality of our approach
is to consider a velocity constraint (all the vehicles belonging to the convoy have the same velocity) and a group
constraint. Consequently, the multitarget state vector contains all the positions of the individual targets and
a single convoy velocity vector. When another target is detected crossing or overtaking the convoy, a specific
algorithm is used and the non-cooperative target is tracked down an adapted particle filter. As demonstrated
by our simulations, a high increase in convoy tracking performance is obtained with our approach.