Peer-to-Peer Distance Measurement among Intelligent Vehicles in a Battlefield

Applications of unmanned vehicles can increase combat effectiveness and personnel safety. These include reconnaissance, surveillance, target acquisition, logistics, minefield and other obstacle detection, explosive disposal, physical security, and operations in contaminated environments. Better communication and GPS technologies are necessary for a convoy of unmanned vehicles to accurately follow a lead-vehicle and maintain safe distance among the vehicles of the convoy. The vehicles of a convoy need reliable and secure communication links to exchange information in real time. The vehicles of a convoy also need better technology to accurately measure distances between them and the lead-vehicle. The error introduced in the position measurement of a vehicle, using standard GPS receivers can be as much as 100 meters. Hence, the distance error between the lead-vehicle and a follower, introduced by standard GPS receivers can be as high as 200 meters [1]. Thus, distance measurement using standard GPS receivers is not acceptable for robotic follower and cooperative driving applications. The use of differential GPS receivers can reduce the distance error between the lead-vehicle and the followers. Measurements using differential GPS receivers require GPS ground stations. However, GPS ground stations may not be readily available in a battlefield. Thus, distance measurement using differential GPS receivers is not possible in a battlefield. This paper presents a technique of distance measurement using two cooperative standard GPS receivers. Our numerical results show that the accuracy in distance measurement using two cooperative standard GPS receivers is as good as that using the differential GPS receivers. Two vehicles can also measure distance between them using infrared and radar technologies. However, infrared and radar technologies require line-of-sight communications. The main advantage of wireless communication technology over infrared and radar technologies is that it does not require line-of-sight communication. This paper also presents a wireless protocol for the cooperative GPS receivers to exchange their data.