Brian H. Wilcox

Lightweight Rovers for Mars Science Exploration and Sample Return

We report on the development of new mobile robots for Mars exploration missions. These lightweight survivable rover (LSR) systems are of potential interest to both space and terrestrial applications, and are distinguished from more conventional designs by their use of new composite materials, collapsible running gear, integrated thermal-structural chassis, and other mechanical features enabling improved mobility and environmental robustness at reduced mass, volume, and power. Our first demonstrated such rover architecture, LSR-1, introduces running gear based on 2D composite struts and 3D machined composite joints, a novel collapsible hybrid composite-aluminum wheel design, a unit-body structural- thermal chassis with improved internal temperature isolation and stabilization, and a spot-pushbroom laser/CCD sensor enabling accurate, fast hazard detection and terrain mapping. LSR-1 is an approximately .7

Sojourner on Mars and Lessons Learned for Future Plantery Rovers

MIL 1.0 meter(Lambda) 2(W X L) footprint six-wheel (20 cm dia.) rocker-bogie geometry vehicle of approximately 30 cm ground clearance, weighing only 7 kilograms with an onboard .3 kilogram multi-spectral imager and spectroscopic photometer. By comparison, NASA/JPLs recently flown Mars Pathfinder rover Sojourner is an 11+ kilogram flight experiment (carrying a 1 kg APXS instrument) having approximately .45 X .6 meter(Lambda) 2(WXL) footprint and 15 cm ground clearance, and about half the warm electronics enclosure (WEE) volume with twice the diurnal temperature swing (-40 to +40 degrees Celsius) of LSR- 1 in nominal Mars environments. We are also developing a new, smaller 5 kilogram class LSR-type vehicle for Mars sample return -- the travel to, localization of, pick-up, and transport back to an Earth return ascent vehicle of a sample cache collected by earlier science missions. This sample retrieval rover R&D prototype has a completely collapsible mobility system enabling rover stowage to approximately 25% operational volume, as well an actively articulated axle, allowing changeable pose of the wheel strut geometry for improved transverse and manipulation characteristics.

Operator-coached machine vision for space telerobotics

In this paper, the rover navigation performance is analyzed on the basis of received rover telemetry, rover uplink commands and stereo images captured by the lander cameras.

Vision-based planetary rover navigation

A prototype system for interactive object modeling has been developed and tested. The goal of this effort has been to create a system which would demonstrate the feasibility of highly interactive operator-coached machine vision in a realistic task environment and to provide a testbed for experimentation with various modes of operator interaction. The purpose for such a system is to use human perception where machine vision is difficult i. e. to segment the scene into objects and to designate their features and to use machine vision to overcome limitations of human perception i. e. for accurate measurement of object geometry. The system captures and displays video images from a number of cameras allows the operator to designate a polyhedral object one edge at a time by moving a 3-D cursor within these images performs a least-squares fit of the designated edges to edge data detected with a modified Sobel operator and combines the edges thus detected to form a wire-frame object model that matches the Sobel data.

Expanding venue and persistence of planetary mobile robotic exploration: new technology concepts for Mars and beyond

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 vehicles 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

Testbed for Studying the Capture of a Small, Free-Flying Asteroid in Space

The domain and technology of mobile robotic space exploration are fast moving from brief visits to benign Mars surface regions to more challenging terrain and sustained exploration. Further, the overall venue and concept of space robotic exploration are expanding-“from flatland to 3D”-from the surface, to sub-surface and aerial theatres on disparate large and small planetary bodies, including Mars, Venus, Titan, Europa, and small asteroids. These new space robotic system developments are being facilitated by concurrent, synergistic advances in software and hardware technologies for robotic mobility, particularly as regard on-board system autonomy and novel thermo-mechanical design. We outline these directions of emerging mobile science mission interest and technology enablement, including illustrative work at JPL on terrain-adaptive and multi-robot cooperative rover systems, aerobotic mobility, and subsurface ice explorers.

Sinkage and slippage estimation for an articulated vehicle

A scaled deployable device has been built and tested for the purpose of evaluating the feasibility of capturing an entire small asteroid in free space. The target asteroid was presumed to have a mass <1000 metric tons, with a longest dimension of <13 meters. It could be spinning and tumbling. It could be a rubble pile – a collection of loosely-bound particles whose cohesion is barely more than the minimum required by the hoop strength defined by the spin rate. It was decided that the only way to confine a rubble pile was to put it in a bag – a fabric or membrane enclosure which completely encapsulated the asteroid, preventing contamination of the solar arrays, radiators, and other optical surfaces of the spacecraft. Clearly this bag had to be deployed, since the largest dimension of the asteroid is significantly larger than the launch shroud of any present launch vehicle. It was decided that a hardware-in-the-loop testbed would be needed, since the physics of physical contact between the asteroid and the deployed capture bag is too complex to credibly model entirely within computer simulation. This testbed was built at 1/5 th -scale for a capture bag assumed 15 meters in diameter (the largest dimension of the asteroid plus a meter on either side). The asteroid mockup was mounted on a robotic arm and force-torque sensors were used to measure the interactions between the spacecraft and the asteroid through the soft material of the capture system. The force-torque measurements were fed into a zero-g simulation of the spacecraft and asteroid, which in turn prescribed the motion of the asteroid relative to the spacecraft. This paper describes the construction and operation of the testbed, including the selection of the bag materials, the configuration of the capture mechanism, the actuators required to deploy, control, and retract the bag, the hardware-in-the-loop simulation and the sensors used to drive it, as well as results from the system.

Keynote address V: Some ambitious NASA mission concepts

This paper describes an approach to estimating in real-time the degree to which an articulated robotic vehicle is undergoing wheel slip and/or sinkage in soft terrain. Robotic vehicles generally have hazard avoidance sensors which measure the shape of the sensible surface, and these can be used to predict what the articulation pose of the vehicle will be as it moves over the surface. An articulated vehicle (one with three or more wheels on each side) can directly measure the shape of the loadbearing surface by combining inclination and articulation sensing. Delays between the actual articulations and the expectations can be explained by wheel slippage. Differences between the expectation and the actual articulations can be explained by sinkage below the sensed surface. If one assumes that successive wheels on each side follow the same profile as the front wheel (sinking the same amount, if any, into the soil), then it is possible to estimate sinkage and slippage separately. A Maximum-A-Posteriori estimation procedure formalizing this heuristic approach is developed and simulated, and the results presented and discussed.

Programmable pipelined image processor

Brian is a JPL Fellow and the Manager of the JPL Space Robotics Technologies Program at JPL since 2010. He a B.S. Physics and B.A. Mathematics, University of California at Santa Barbara (highest honors) (1973) and a M.S. Electrical Engineering, University of Southern California (1993). In the 1980s he worked as robotics engineer assigned to Mars Rover Sample Return Mission. Between 1985 and 2005 he was the Supervisor, JPL Robotic Vehicles Group, during which time the group was responsible for the development of the Sojourner Mars Rover electronics, on-board software, mission operations software tool development, and the actual mission operations of Sojourner. Group members continued in similar key roles on MER and MSL rovers. Between 1995 and 2003 he was the Principal Investigator of the Nanorover and Nanorover Outposts and from 2004 to present, the Principal Investigator of the All-Terrain Hex-Limbed, Extra-Terrestrial Explorer (ATHLETE) which has six wheels on the ends of six limbs that can be used for general-purpose manipulation as well as extremeterrain mobility. He was awarded NASA Exceptional Engineering Achievement Medal, for contributions to planetary rover research in 1992.