Cooperative GPS navigation

Many envisioned scenarios for the utilization of autonomous vehicles include groups of vehicles working together to accomplish some common objective. These scenarios typically assume that each agent has an accurate estimate of its own location and the location of other vehicles in the group. The most widely used technology for estimating position today is the Global Positioning System (GPS). Unfortunately, in many scenarios where multiple autonomous vehicles may be utilized, the ability for each agent to independently estimate its location using GPS may be degraded due to occlusions inherent in the operating terrain (e.g., urban terrain, forests, or jungles.) In this paper, we propose an approach for making groups of autonomous agents more robust to occlusions of the GPS signals. By communicating pseudorange, relative position, and local clock bias estimates between agents in a group, a “cooperative GPS receiver” is created that has two significant advantages. First the cooperative GPS location estimates are considerably more accurate than each individual GPS estimate. Second, GPS “lock” can be obtained in situations where individual agents would be unable to obtain a sufficient number of satellite signals to estimate location. We demonstrate the feasibility of the cooperative GPS algorithm through an experimental setup with two GPS-enabled agents.