Mobility is a key requirement for future Mars surface exploration missions. Many robotic tasks, such as area surveys, sample collection, and life detection, must be performed autonomously, and this will require greatly enhanced sensing capabilities for navigation over the uncertain and potentially hostile Martian terrain. A GPS-like drift-free RF positioning system would be highly beneficial as an augmentation to conventional rover positioning systems based on odometers and inertial sensors. Although it is possible to construct a GPS-like local-area navigation system without a complete satellite constellation by deploying pseudolites on the Martian surface, it would be extremely difficult to place pseudolites on Mars at precisely known locations relative to each other.
3-D Mars Navigation using GPS Transceiver Arrays (Concept)
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). By utilizing bi-directional 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.The two-dimensional navigation and self-calibration capability of the SCPA (a planar array with three static transceivers and one mobile unit with planar motion) has been validated previously in field trials performed at NASA Ames Research Center with the K9 Mars Rover.
Field Demonstration of the 3-D SCPA
This research extends the previous work to examine the 3-D navigation capability of the SCPA by utilizing GPS transceiver arrays. Possible target applications of the 3D-SCPA include navigation and guidance for aerial vehicles such as balloons and airplanes. These aerial vehicles could be the next generation of Mars exploration platforms, and could perform scientific surveys over much broader areas than rovers. The 3D-SCPA could also be useful as a guidance aid when landing vehicles at precise locations of interest.
3-D Self-Calibration Result
3-D SCPA Demo at Stanford Roble Field, August 2002 [MPG VCD 360x240 6MB]
Last modified Mon, 1 Nov, 2010 at 14:47