Autonomous Ground Systems (AGS)


by Ray Wilhelm; Cristian Balas; Anne Schneider; William Klarquist; Alberto Lacaze; Karl Murphy


In this paper, we present CLICS, a program that optimizes convoy vehicle tracks by intelligently combining sensor updates of all vehicles in the convoy in a distributed, cooperative localization system. Currently, follower vehicles in the convoy rely either on GPS breadcrumbs from the lead vehicle, or rely on sensing the location of its predecessor and following its path. However, GPS availability and accuracy oftentimes cause the former solution to fail, and accumulated errors in tracking and control in long convoys can cause the latter solution to fail. Robotic Research’s CLICS system attempts to overcome these problems by (1) integrating multiple heterogeneous sensor outputs from multiple vehicles (2) developing a distributed, real-time non-linear estimation of inter-vehicle pose using spring network providing coordinated localization for members of a vehicle convoy, and (3) real-time robust synchronization of information amongst the convoy, and local convoy and mission level planning. Using the smooth relative navigation solution from the inertial measurement unit (IMU), CLICS inserts virtual “springs” between a vehicle’s navigation solution and other vehicles’ navigation solutions by using inter-vehicle sensing updates. An example of a common spring is a range and angle from one vehicle to another. These “springs” pull the position history of the vehicle with a strength based upon the reliability of the input data. This is done through a nonlinear optimization algorithm that computes an optimal track for each vehicle in the convoy.