3-D Capabilities for GPS Transceiver Arrays

Abstract

The Aerospace Robotics Laboratory (ARL) at Stanford University has developed a GPS pseudolite-based local- area navigation system for Mars rovers, called a Self- Calibrating Pseudolite Array (SCPA) [1]. By utilizing bidirectional ranging GPS transceivers (incorporating separate pseudolites and GPS receivers) scattered over a local area, the SCPA is capable of drift-free centimeter- level localization of the rover with respect to the local array. Relative motion between the rover and the ground- based transceivers is sufficient to determine the precise configuration of the array, eliminating the need for a priori position information or precise placement of the devices. This paper extends the previous work to examine the three-dimensional navigation capability of the SCPA for mobile vehicles moving out of the plane of the ground- based GPS transceiver array. Simulation results show that the SCPA self-calibration algorithm can be applied to 3-D positioning, successfully resolving the relative 3-D trajectories of mobile vehicles with respect to the ground- based array. This paper also presents field demonstrations that validate the actual 3-D positioning capability of the SCPA by using a mobile aerial unit (balloon) equipped with a GPS transceiver. These experimental results show that the 3D-SCPA is able to resolve both the balloon and rover 3-D trajectories relative to the ground-based array to centimeter-level accuracy, starting with no a priori knowledge of the ground-based pseudolite locations.