A new laser-based optical sensor system that provides hazard detection for planetary rovers is presented. The sensor can support safe travel at speeds up to 12 cm/second for large (1 m) rovers in full sunlight on Earth or Mars. This is at least a 5 times improvement over the sensor aboard NASA's Mars Pathfinder rover. The system overcomes limitations in the older design that require image differencing to detect a laser stripe in full sun. The new system ensures the projected laser light is detectable in a single image, eliminating the requirement for additional difference images. The improvement is significant since any reduction in image gathering or processing time provides for faster rover motion. The savings are even more important in the case of a Mars rover since power and radiation-hardening requirements lead to severely constrained computational resources. The paper includes a thorough discussion of design details and tradeoffs for optical hazard sensing that will benefit future efforts in this area.

In 1996, NASA will launch the Mars Pathfinder spacecraft, which will carry an 11 kg rover to explore the immediate vicinity of the lander. To assess the capabilities of the rover, the authors have constructed a new microrover testbed consisting of the Rocky 3.2 vehicle and an indoor test arena containing Mars analog terrain and overhead cameras for automatic, real-time tracking of the true rover position and heading. In this paper, the authors present initial performance evaluation results obtained with this testbed. The authors first decompose rover navigation into four major functions: goal designation, rover localization, hazard detection, and path selection. The authors then describe the Mars Pathfinder approach to each function, present results to date of evaluating the performance of each function, and outline their approach to enhancing performance for future missions. The results show key limitations in the quality of rover localization, the speed of hazard detection, and the ability of behavior control algorithms for path selection to negotiate the rock frequencies likely to be encountered on Mars.

A program to develop planetary rover technology is underway at the Jet Propulsion Laboratory (JPL) under sponsorship of NASA. Developmental systems with the necessary sensing, computing, power, and mobility resources to demonstrate realistic forms of control for various missions have been developed, and initial testing has been completed. These testbed systems and the associated navigation techniques used are described. Particular emphasis is placed on three technologies: Computer-Aided Remote Driving (CARD), Semiautonomous Navigation (SAN), and behavior control. It is concluded that, through the development and evaluation of such technologies, research at JPL has expanded the set of viable planetary rover mission possibilities beyond the limits of remotely teleoperated systems such as Lunakhod. These are potentially applicable to exploration of all the solid planetary surfaces in the solar system, including Mars, Venus, and the moons of the gas giant planets.>

Future missions to the moon or Mars will use planetary rovers for exploration or construction tasks. Operation of these rovers as unmanned robotic vehicles with some form of semi-autonomous control is desirable to reduce the cost and increase the capability and safety of many types of missions. A program to develop semi-autonomous navigation (SAN) was initiated in late 1988 at the Jet Propulsion Laboratory (JPL) under sponsorship of the Office of Aeronautics and Exploration Technology of the National Aeronautics and Space Administration (NASA). A testbed vehicle with all necessary power, sensing, and computing resources on-board to demonstrate SAN has been developed and initial testing has been completed. Vision-based navigation techniques used on this vehicle and planned for implementation are described.

A useful space telerobot for on-orbit assembly, maintenance, and repair tasks must have a sensing and perception subsystem which can provide the locations, orientations, and velocities of all relevant objects in the work environment. This function must be accomplished with sufficient speed and accuracy to permit effective grappling and manipulation. Appropriate symbolic names must be attached to each object for use by higher-level planning algorithms. Sensor data and inferences must be presented to the remote human operator in a way that is both comprehensible in ensuring safe autonomous operation and useful for direct teleoperation. Research at JPL toward these objectives is described.