Autonomous systems of multiple-agent air/ground robotic units for exploration of the surfaces of remote planets are undergoing development. Modified versions of these systems could be used on Earth to perform tasks in environments dangerous or inaccessible to humans: examples of tasks could include scientific exploration of remote regions of Antarctica, removal of land mines, cleanup of hazardous chemicals, and military reconnaissance.

A basic system according to this concept (see figure) would include a unit, suspended by a balloon or a blimp, that would be in radio communication with multiple robotic ground vehicles (rovers) equipped with video cameras and possibly other sensors for scientific exploration. The airborne unit would be free-floating, controlled by thrusters, or tethered either to one of the rovers or to a stationary object in or on the ground. Each rover would contain a semi-autonomous control system for maneuvering and would function under the supervision of a control system in the airborne unit. The rover maneuvering control system would utilize imagery from the onboard camera to navigate around obstacles. Avoidance of obstacles would also be aided by readout from an onboard (e.g., ultrasonic) sensor. Together, the rover and airborne control systems would constitute an overarching closed-loop control system to coordinate scientific exploration by the rovers.

A Balloon-Borne Unit would supervise the maneuvers of multiple rovers from an overhead perspective.

The rovers would be relatively inexpensive (and, hence, somewhat expendable) units equipped with task-specific sensors. The redundancy afforded by the use of many such rovers (in contradistinction to a single, more generally capable and thus more expensive rover) would help to ensure the success in the event of loss of one or a few rovers. The use of many rovers would also make it possible to cover a large terrain area in a short time. The airborne unit would have an overhead perspective that would enable it to provide guidance to the rovers. For example, the airborne unit could "see" a scientifically interesting terrain feature or a hazard or obstacle hidden from a rover camera by an intervening hill. One or more camera(s) in the airborne unit would acquire terrain images that would be digitized and processed by feature-extraction algorithms. The feature data would be used by planning algorithms to choose potential targets for close examination by the rovers and for planning the paths of the rovers across the terrain. The paths would be chosen to enable the rovers to avoid obstacles and hazards (e.g., hills and cliffs) on their way to their designated targets. Among the planning algorithms would be algorithms for prioritization and sequencing of targets. There would also be algorithms for replanning in response to information on local conditions observed by the rovers and in response to deviations of rovers from planned paths.

Once a rover reached a target, it would acquire close-up images and possibly other sensory information about the target. Features would be extracted from the image data and from any other sensory data to characterize the site. Then the rover would be commanded to move on to the next target. The exploratory process as described thus far would be repeated by each rover until all targets in the terrain area of interest had been examined. A partly functional model of such a system operates in a 4- by-5-ft (1.22-by-1.52-m) test bed that simulates terrain.

The test bed is strewn with variously colored and shaped blocks to simulate targets and obstacles. An overhead view is provided by a camera on a mast above the center of the test bed. Miniature rovers equipped with cameras maneuver on the simulated terrain. At the time of reporting the information for this article, efforts to develop a more fully functional model for testing advanced hardware and software designs were under way.

This work was done by Wolfgang Fink, Tien-Hsin Chao, Jay Hanan, and Mark Tarbell of Caltech, and James M. Dohm of the University of Arizona for NASA's Jet Propulsion Laboratory. For further information, access the Technical Support Package (TSP) free on-line at www.techbriefs.com/tsp under the Electronics/Computers category.

In accordance with Public Law 96-517, the contractor has elected to retain title to this invention. Inquiries concerning rights for its commercial use should be addressed to:

Innovative Technology Assets Management
JPL
Mail Stop 202-233
4800 Oak Grove Drive
Pasadena, CA 91109-8099
(818) 354-2240
E-mail: This email address is being protected from spambots. You need JavaScript enabled to view it.

Refer to NPO-40428, volume and number of this NASA Tech Briefs issue, and the page number.



This Brief includes a Technical Support Package (TSP).
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Multiple-Agent Air/Ground Autonomous Exploration Systems

(reference NPO-40428) is currently available for download from the TSP library.

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