Scientists and engineers at NASA's Jet Propulsion Laboratory have begun an extensive period of field testing a semi-autonomous navigation system on a computer-operated vehicle that may be used in future planetary explorations.
The first, continuous semi-autonomous navigation (SAN) traverse, in rough natural terrain, was achieved May 7, 1990.
Brian Wilcox, supervisor of the Robotic Sensing and Perception Group, said the summer-long testing program would be carried out mostly in the Pasadena Arroyo, a dry river bed, adjacent to JPL.
The program is part of NASA's new exploration technology initiative which is to develop technologies for the Space Exploration Initiative (SEI) announced by President Bush last July.
Developing new technologies, including a new generation of planetary rovers, is seen as critical to the success and cost effectiveness of the SEI. The Planetary Rover project will develop systems to enable the manned and unmanned vehicles needed for surface transportation.
Surface transportation systems required by the SEI include unmanned rovers for outpost site survey and for regional robotic exploration and science; piloted rovers for transportation both local and long range, and unmanned cargo handling, construction and mining.
Increased traverse distance, longer life and autonomous operations are required for the unmanned roving vehicles for the program. Traverse distances of up to several kilometers per Earth day and a mission life from one to five years is desired for the next generation of robotic exploring vehicles.
The operation of an autonomous unmanned rover, whether on the surface of Mars with round-trip light time of between eight and 40 minutes, or any other situation resulting in minutes of time delay, involves an entirely unproven technology.
Two advanced forms of unmanned rover navigation are under development at JPL. They are computer aided remote driving (CARD) and semi-autonomous navigation (SAN).
The CARD technique allows a human operator to remotely drive a vehicle by planning and designating an extended (10s of meters) obstacle-free path with a three dimensional display of images from stereo cameras aboard the vehicle. The path is then transmitted to the vehicle for autonomous execution.
The SAN technique allows a human operator to determine a nominal extended route (10s of kilometers) for the vehicle, with a specific path taken by the vehicle around local obstacles determined automatically from the rover's sensor data and stored data base.
The navigation testbed is a six-wheeled, three-body, articulated vehicle the experimenters call "Robby." It's about 13 feet long, five-feet wide, and more than 6.5-feet high. Its 35inch diameter wheels and articulated body permit it to go over obstacles a meter high.
The 2,500-pound vehicle contains two computer systems, one for perception and planning and one for control of the actuators in the wheel drive and arm control. The robotic arm has six links and six degrees of freedom with an additional pivot axis and gripper providing two more degrees of freedom.
There are four cameras on the pan-tilt head capable of stereo correlation to provide three-dimensional images of objects. A motor generator provides 3,500 watts of power and batteries provide 24 volts.
Other parts of the rover program include the development of advanced mission operation, mobility and power technology at JPL; the development of an innovative "legged" vehicle concept, as opposed to using wheels, at Carnegie Mellon University in Pittsburgh, Pa.; mission operations research at the Ames Research Center at Moffett Field, Calif., and piloted rover technology at the Marshall Space Flight Center at Huntsville, Ala.
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