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Wilcox, Brian H.

Publications and source records attributed to Wilcox, Brian H..

At least 37 records · Page 2

Athlete: A Mobility and Manipulation System for the Moon

A robotic vehicle called ATHLETE - the All-Terrain Hex-Limbed, Extra-Terrestrial Explorer is described, along with initial results of Field tests of two prototype vehicles. This vehicle concept is capable of efficient rolling mobility on moderate terrain and walking mobility on extreme terrain. Each limb has a quick-disconnect tool adapter so that it can perform general purpose handling, assembly, maintenance, and servicing tasks using any or all of the limbs.

mobility↗

Low-Cost Propellant Launch to Earth Orbit from a Tethered Balloon

Propellant will be more than 85% of the mass that needs to be lofted into Low Earth Orbit (LEO) in the planned program of Exploration of the Moon, Mars, and beyond. This paper describes a possible means for launching thousands of tons of propellant per year into LEO at a cost 15 to 30 times less than the current launch cost per kilogram. The basic idea is to mass-produce very simple, small and relatively low-performance rockets at a cost per kilogram comparable to automobiles, instead of the ~25X greater cost that is customary for current launch vehicles that are produced in small quantities and which are manufactured with performance near the limits of what is possible. These small, simple rockets can reach orbit because they are launched above ~95% of the atmosphere, where the drag losses even on a small rocket are acceptable, and because they can be launched nearly horizontally with very simple guidance based primarily on spin-stabilization. Launching above most of the atmosphere is accomplished by winching the rocket up a tether to a balloon. A fuel depot in equatorial orbit passes over the launch site on every orbit (approximately every 90 minutes). One or more rockets can be launched each time the fuel depot passes overhead, so the launch rate can be any multiple of 6000 small rockets per year, a number that is sufficient to reap the benefits of mass production.

Earth orbits↗

High mobility vehicle

A vehicle, for driving over a ground surface, has a body with a left side, a right side, a front and a back. The vehicle includes left and right drive mechanisms. Each mechanism includes first and second traction elements for engaging the ground surface and transmitting a driving force between the vehicle and ground surface. Each mechanism includes first and second arms coupled to the first and second traction elements for relative rotation about first and second axis respectively. Each mechanism includes a rotor having a third axis, the rotor coupled to the body for rotation about the third axis and coupled to the first and second arms for relative rotation about the third axis. The mechanism includes first and second drive motors for driving the first and second traction elements and first and second transmissions, driven by the first and second motors and engaging the rotor. Driving the first and second traction elements simultaneously rotates the rotor relative to the first and second arms, respectively.

Wilcox, Brian H.↗

A Novel Approach to Exploring the Mars Polar Caps

The Martian polar caps contain some of the most important scientific sites on the planet. There is much interest in exploring them with a view to understanding their role in the Mars climate system. By gaining access to the stratigraphy of the polar terrain, it is probable that one can access the climate history of the planet. Additionally, investigations aimed at localizing subsurface water--liquid or solid--are not only of great scientific interest but are also germane to the long-term interests of the manned space flight program. A major difficulty with polar exploration is access. Current techniques using chemical propulsion, Holman transfers, and direct-entry landers with aeroshells have limited capability to access the polar terrain. For the near term the authors propose a new approach to solving this transportation issue by using Solar Electric Propulsion (SEP), recently flight demonstrated on NASA's DS1 Mission to an asteroid and a comet. For a longer-term approach there are additional ways in which access to Mars, as well as other planets, can be significantly improved. These include the use of Chaos orbit theory to enable transportation between LaGrange points in the solar system, gossamer structures enabling very low-mass mobility, and advanced ascent vehicles. In this paper the authors describe how a 1000-kG payload can be transported to the surface of Mars and a polar sample obtained and returned to Earth in less than five years using SEP. A vision of how this approach can be integrated into a long-term Mars exploration strategy building toward the future is also discussed.

Brophy, John R.↗

Nanorovers and Subsurface Explorers for Mars

Recent advances in microtechnology and mobile robotics have made it feasible to create extremely small automated or remote-controlled vehicles which open new application frontiers. One of these possible applications is the use of nanorovers (robotic vehicles with a mass of order one kilogram or less) in planetary exploration. NASA and Japan's Institute of Space and Astronautical Science (ISAS) are cooperating on the first mission to collect samples from the surface of an asteroid and return them to Earth for in-depth study. The ISAS MUSES-C mission will be launched on a Japanese launch vehicle in July 2002 from Japan toward a rendez-vous with the asteroid 1989ML in September 2003. A NASA-provided nanorover will conduct in-situ measurements on the surface. With a mass of about one kilogram, the rover experiment will be a direct descendant of the technology used to build the Sojourner rover. The rover will carry three science instruments: (1) a visible imaging camera, (2) a near-infrared point spectrometer, and (3) an alpha X ray spectrometer. The solar-powered rover will move around the surface of 1989ML collecting imagery data, which are complimentary to the spacecraft investigation. The imaging system will be capable of making surface texture, composition, and morphology measurements at resolutions better than one millimeter. The rover will transmit this data to the spacecraft for relay back to Earth. Due to the microgravity environment on 1989ML, the rover has been designed to right itself in case it flips over. Solar panels on four sides of the rover will ensure that enough power will always be available to the rover to activate the motors needed to turn over. Posable struts will allow the rover to position its chassis such that the camera can be pointed straight down at the surface or straight up at the sky.

Wilcox, Brian H.↗

Embedded Control of a Miniature Science Rover for Planetary Exploration

A rover prototype has been integrated into a package of several hundred grams in mass. Aspects of the embedded rover control and software implementation are discussed which enable mobility and operation of science instruments for navigation and surface exploration.

Rovers Planetary Exploration↗

Method for surmounting an obstacle by a robot vehicle

Surmounting obstacles in the path of a robot vehicle is accomplished by rotating the wheel forks of the vehicle about their transverse axes with respect to the vehicle body so as to shift most of the vehicle weight onto the rear wheels, and then driving the vehicle forward so as to drive the now lightly-loaded front wheels (only) over the obstacle. Then, after the front wheels have either surmounted or completely passed the obstacle (depending upon the length of the obstacle), the forks are again rotated about their transverse axes so as to shift most of the vehicle weight onto the front wheels. Then the vehicle is again driven forward so as to drive the now lightly-loaded rear wheels over the obstacle. Once the obstacle has been completely cleared and the vehicle is again on relatively level terrain, the forks are again rotated so as to uniformly distribute the vehicle weight between the front and rear wheels.

Wilcox, Brian H.↗

Computer-Aided Remote Driving

System for remote control of robotic land vehicle requires only small radio-communication bandwidth. Twin video cameras on vehicle create stereoscopic images. Operator views cross-polarized images on two cathode-ray tubes through correspondingly polarized spectacles. By use of cursor on frozen image, remote operator designates path. Vehicle proceeds to follow path, by use of limited degree of autonomous control to cope with unexpected conditions. System concept, called "computer-aided remote driving" (CARD), potentially useful in exploration of other planets, military surveillance, firefighting, and clean-up of hazardous materials.

Wilcox, Brian H.↗

Compact Robotic Vehicle

Radio-controlled microrover features light weight and agility. Miniature robotic vehicle, called Go-For, implements new fork-wheeled mobility concept to traverse extremely rough terrain. Weighs 4 kg and is 0.4 m long, climbs over obstacles as large as 60 percent of its length. Mobility concept applied to much larger vehicles. Demonstrates such applications as exploration of planetary surfaces, military surveillance, and assessing hazardous situations. Video camera on vehicle sends images to control station, where human supervisor chooses sequence of paths to traverse to reach locations of interest. For planetary exploration, spectrometer and seisometer on vehicle sends scientific data to control station, and onboard tools collect soil and rock samples. Terrestrial version equipped similarly to take samples in chemically and/or biologically contaminated areas.

Wilcox, Brian H.↗

Experimental Semiautonomous Vehicle

Semiautonomous rover vehicle serves as testbed for evaluation of navigation and obstacle-avoidance techniques. Designed to traverse variety of terrains. Concepts developed applicable to robots for service in dangerous environments as well as to robots for exploration of remote planets. Called Robby, vehicle 4 m long and 2 m wide, with six 1-m-diameter wheels. Mass of 1,200 kg and surmounts obstacles as large as 1 1/2 m. Optimized for development of machine-vision-based strategies and equipped with complement of vision and direction sensors and image-processing computers. Front and rear cabs steer and roll with respect to centerline of vehicle. Vehicle also pivots about central axle, so wheels comply with almost any terrain.

Wilcox, Brian H.↗

Robot Grasps Rotating Object

Experimental robotic system semiautomatically grasps rotating object, stops rotation, and pulls object to rest in fixture. Based on combination of advanced techniques for sensing and control, constructed to test concepts for robotic recapture of spinning artificial satellites. Potential terrestrial applications for technology developed with help of system includes tracking and grasping of industrial parts on conveyor belts, tracking of vehicles and animals, and soft grasping of moving objects in general.

Wilcox, Brian H.↗

Optoelectronic Ranging Sensor For Robotic Vehicle

Proposed optoelectronic ranging system for robotic vehicle provides information on distances to points in natural scene by use of pinhole mask to sample texture in scene and determines whether portion of scene corresponds to each pinhole in focus (whether it lies at focal distance). System has no moving parts, requires little computation, and consumes only few watts of power. Passive in sense that it does not include any artificial sources of light, relying instead on sunlight reflected from scene.

Wilcox, Brian H.↗

Vision-based planetary rover navigation

NASA and JPL have developed a testbed 'planetary rover' vehicle with sufficient power supplies, sensors, and computational resources for the demonstration of semiautonomous navigation. Attention is presently given to this vehicle's vision-based navigation techniques. The proposed design and its variants allow advantage to be taken of enormous quantities of both spatial and temporal information that are normally wasted, by sampling very fine detail over the full focal plane area to precisely determine those parts of the image that are accurately at the focus range of the pinhole array used. This should generate accurate and reliable real-time range information in a wide variety of natural scenes, with little or no computation.

Wilcox, Brian H.↗

Planetary Rover local navigation and hazard avoidance

A Planetary Rover will have to be able to navigate through its local environment autonomously, due to communication delays. This implies that the vehicle must be able to sense its environment, plan a course through that environment, and react appropriately to unexpected situations as they appear. All this must be done while guiding the vehicle toward the goals that have been given to it from its operators on the earth. This paper describes research at the Jet Propulsion Laboratory which concentrates on the sensing, perception, planning and execution monitoring that must be carried out by the rover to ensure that a safe and efficient path is found by the rover, and that that path is performed correctly.

Miller, David P.↗

Time-delayed operation of a telerobot via geosynchronous relay

Operation of a telerobot is compromised if a time delay of more than a few hundred milliseconds exists between the operator and remote manipulator. However, the most economically attractive way to perform telerobotic functions such as assembly, maintenance, and repair in Earth orbit is via geosynchronous relay satellites to a ground-based operator. This induces loop delays from one-half to two seconds, depending on how many relays are involved. Such large delays makes direct master-slave, force-reflecting teleoperated systems infeasible. Research at JPL on a useful telerobot that operates with such time delays is described.

Wilcox, Brian H.↗

Machine vision for space telerobotics and planetary rovers

Machine vision allows a non-contact means of determining the three-dimensional shape of objects in the environment, enabling the control of contact forces when manipulation by a telerobot or traversal by a vehicle is desired. Telerobotic manipulation in Earth orbit requires a system that can recognize known objects in spite of harsh lighting conditions and highly specular or absorptive surfaces. Planetary surface traversal requires a system that can recognize the surface shape and properties of an unknown and arbitrary terrain. Research on these two rather disparate types of vision systems is described.

Wilcox, Brian H.↗

A vision system for a Mars rover

A Mars rover must be able to sense its local environment with sufficient resolution and accuracy to avoid local obstacles and hazards while moving a significant distance each day. Power efficiency and reliability are extremely important considerations, making stereo correlation an attractive method of range sensing compared to laser scanning, if the computational load and correspondence errors can be handled. Techniques for treatment of these problems, including the use of more than two cameras to reduce correspondence errors and possibly to limit the computational burden of stereo processing, have been tested at JPL. Once a reliable range map is obtained, it must be transformed to a plan view and compared to a stored terrain database, in order to refine the estimated position of the rover and to improve the database. The slope and roughness of each terrain region are computed, which form the basis for a traversability map allowing local path planning. Ongoing research and field testing of such a system is described.

Wilcox, Brian H.↗