Formation Planning and Control of UGVs with Trailers

This paper provides a practical framework for planning and control of formations of multiple unmanned ground vehicles with trailers to traverse between goal points in a dynamic environment. This framework allows on-line planning of the formation paths using A* search algorithm based on the current sensor data. The formation is allowed to dynamically change in order to avoid obstacles in the environment while minimizing a cost function aimed at obtaining collision-free and deadlock-free paths. Based on a feasible path for a leader of the group and the differential flatness property of a truck-tractortrailer system, the trajectory planner satisfies the kinematic constraints of the individual vehicles while accounting for inter-vehicle collision and path constraints. Also, optimization techniques are used to on-line change the path of the truck-tractor-trailer system. Illustrative laboratory implementation of groups of unmanned ground vehicles with trailers in formations is presented.