2.2.2 Lunar Rovers

This segment of the program supports the development of robotics to satisfy the planned requirements for exploration of the surfaces of the Moon. These plans call for robotic reconnaissance and surveying systems preceding the eventual human missions to these bodies. During such missions robots will explore potential landing sites and areas of scientific interest, place science instruments, gather samples for analysis and possible return to Earth, gather and transmit video imagry, and provide images required to generate "virtual environments" of the Lunar surface. The robotic systems required for these operations will require high levels of local autonomy, including the ability to perform local navigation, regulate on-board resources, and schedule activities, all with limited ground command intervention. The objectives of the tasks within this segment of the program are to develop these abilities, as well as conduct research into mobility systems, miniature mechanisms, planning, and on-board navigation. Specific applications are to programs planned by the Space Science and Exploration user communities, as well as other commercial lunar resource utilization opportunities.

Lunar Rover Demonstration

Autonomous Rover Technologies

Dante II/Mt. Spurr

Technology Transfer Roadmap Details

Lunar Rover Demonstration

The purpose of the Lunar Rover Demonstration task is to develop and demonstrate a convincing, comprehensive mobile robot mission capability required for a Lunar Rover Flight Mission. The project will demonstrate rover technologies suitable for lunar missions, and provide those technologies to NASA and commercial interests for scientific and private enterprise on the Moon.

Technical Objectives:

The objective of the Lunar Rover Demonstration task is to develop and demonstrate a convincing, comprehensive mobile robot mission capability required for a Lunar Rover Flight Mission. The project will demonstrate rover technologies suitable for lunar missions, and provide those technologies to NASA and commercial interests for scientific and private enterprise on the Moon.

Approach:

To achieve the mobile robot lunar mission capabaility, the task will focus its efforts on two fronts: development of a lunar-relevant prototype rover, and mission analysis and simulation.

1) Lunar-Relevant Rover Development. The rover will consist of a number of subsystems, including locomotion, communication, imagery, computing, electronics, software, power, and thermal control. The development cycle applied to each of these subsystems will include configuration, design, component design, fabrication, assembly, and test. Simultaneously, we will perform detailed simulations to quantify performance and increase confidence in the design.

2) Mission Analysis and Simulation. In one promising scenario being considered, a rover traverses a thousand kilometers over two years. Throughout, scientists and commercial sponsors share time commanding the rover, while the public participates in the mission through interactive theme parks or television. We will perform end-to-end mission simulations to evaluate operations. Simulation will include teleoperation, ground stations, visualization, inter-rover communication, and transition modes (rover transition from "observer" to "explorer", ground station transition from site to site). In addition, we will perform failure mode analysis and develop fault recover methods.

The project will leverage the insights and practical tools developed under the Autonomous Rover Technologies task. Specifically, it will transfer results of the basic research in perception, rover configuration, and task-level control and apply them in system design, development, and demonstration.

Focus and Direction:

FY 94 Demonstrate natural terrain traverse with an existing but modified rover; form Lunar Rover Consortium; configure new rover.

FY 95 Conduct Preliminary Design Review (PDR) for rover and its role in a lunar mission. Scope of rover review to include locomotion, communication, imagery, computing and electronics, software, power, and thermal control systems. Additional scope to include ground stations, visualization, failure analysis, fault recovery, and transition modes (rover transition from "observer" to "explorer", ground station transition from site to site).

FY 96 Build lunar-relevant prototype rover, including all subsystems except power and thermal control, and demonstrate motion control.

FY 96 Conduct Critical Design Review (CDR) for rover and its role in a lunar mission. Scope of CDR to be the same as for PDR, and to include review of results from two detailed testing programs: (1) testing of lunar-relevant rover; and (2) component testing of actuators, sensors, and processors.

Planned Milestones:

Dec 94 Conduct Configuration Design Review based on design document entitled "Lunaquest Mission Concept."

Mar 95 Demonstrate functional simulation of rover operating on synthetic terrain.

Jun 95 Produce design documents for locomotion, pointing, and visualization subsystems.

Sep 95 Conduct Preliminary Design Review (PDR) for rover and its role in a lunar mission. Scope of rover review to include locomotion, communication, imagery, computing, electronics, software, power, and thermal control systems. Additional scope to include ground stations, visualization, failure analysis, fault recovery, and transition modes (rover transition from "observer" to "explorer", ground station transition from site to site).

Dec 95 Emulate failure modes and reliability measures.

Apr 96 Complete ground station mockup, including communication links and devices for audience visualization and participatory interaction.

Jul 96 Fabricate lunar-relevant prototype rover.

Aug 96 Demonstrate motion control of lunar-relevant prototype rover, including all subsystems except power and thermal control.

Sep 96 Conduct Critical Design Review (CDR) for rover and its role in a lunar mission. Scope of CDR to be the same as for PDR, and to include review of results from two detailed testing programs: (1) testing of lunar-relevant rover; and (2) component testing of actuators, sensors, and processors.

Point of Contact:
Red Whittaker
(412) 268-6559
red@ri.cmu.edu

Autonomous Rover Technology

The purpose of the Autonomous Rover Technologies task is to develop innovative perception, rover configuration, planning, and task-level control technologies that enable mobile robots to operate under control modes ranging from safeguarded teloperation to full autonomy. The aim is to enable rovers to operate reliably, over long durations in rugged, natural, unstructured environments. Further, technology development will feed into and respond to the Lunar Rover Demonstration focused research program.

Technical Objectives:

The objective of the Autonomous Rover Technologies task is to develop innovative perception, rover configuration, planning, and task-level control technologies that enable mobile robots to operate under control modes ranging from safeguarded teloperation to full autonomy. The aim is to enable rovers to operate reliably, over long durations in rugged, natural, unstructured environments.

Approach:

The technology development will focus on the key areas of perception, planning, task-level control, and integrated systems.

1) Perception. Technologies that will be developed include (a) mapping local surface geometry using stereo vision, using weak calibration methods, (b) estimating rover position, using multiple sensor fusion, map registration, and visual landmarks, and (c) mapping large-scale surface geometry, using topographic analysis.

2) Planning. The focus will be on planning for obstacle avoidance, using stereo, in rough, previously unknown terrain. Extension to current planning techniques will enable the robot to handle noisier sensor and stereo data, and more varied terrain. Techniques to be investigated include planning under uncertainty and risk, and more sophisticated merging of multiple stereo datasets.

3) Task-level Control. The development of task-level control technologies will focus on reliable operation: Strategies for monitoring execution of plans and behaviors for reacting to exceptional situations will be developed and integrated into the existing robot system. In addition, tools will be developed to aid in the specification and analysis of distributed, concurrent robotic systems.

4) Integrated Systems. The perception, planning, and task-level control technologies will be tested in an integrated, real-world navigation system. Initially, the locomotion platform will be the Ratler, and when available it will be a lunar-worthy rover. As the Lunar Rover Demonstration task develops components, such as computing platforms and telemetry systems, they will be integrated and tested with the navigation system.

Focus and Directions:

FY 94 Develop and demonstrate technologies including stereo mapping with no artificial calibration targets; Daedalus framewalker fabricated and assembled; formal model of TCA using Z notation and temporal logic.

FY 95 Develop and demonstrate technologies for off-board safeguarded teloperation control from a remote operator station. Demonstrate technologies in 10 km test with existing rover in natural terrain. Primary mode of fault recovery will be operator intervention (such as via direct teleoperation control).

FY 96 Develop and demonstrate technologies for on-board safeguarded teleoperation control and participatory multimedia interactions with novice users. Demonstrate technologies in 10 km test with self-contained rover in lunar mare-like terrain. Primary mode of fault recovery will be supervised intervention (such as downloading new paths).

FY 97 Develop and demonstrate technologies for long-duration, on-board autonomous control. Demonstrate technologies in 10 km test of autonomous operation, with self-contained rover with a 1 kilometer mean distance between operator interventions. Demonstrate rover-requested intervention (such as recharging batteries or resetting comm link).

FY 98 Develop and demonstrate technologies for mixed mode control blending safeguarded teleoperation and autonomous control. Demonstrate technologies in 100 km test in lunar highland-like terrain with participatory interactions from remote audience.

FY 99 Develop and demonstrate technologies for highly-tolerant mixed mode control. Demonstrate technologies in 100 km test of autonomous operation in mixture of mare and highland terrains, with self-contained rover and a 1 day mean time between operator intervention.

Point of Contact:
Eric Krotkov
(412) 268-3058
epk@cs.cmu.edu

Dante II/Mt. Spurr

"Dante" is a walking and rappelling robot for exploration of volcano craters, developed at the Carnegie-Mellon University Robotics Institute. A primary objective of the Dante program is to demonstrate robotic exploration of harsh, barren, and steep terrains such as those found on the moon and planets. Active volcanos in the Earth's polar regions have been selected as excellent terrain and climatic analogs to lunar and planetary environments. Additionally, these volcanos offer excellent scientific agenda: high-temperature, fumarole gas samples are prized by volcanic science, yet their sampling poses significant challenge. In 1993 eight volcanologists were killed in two separate events while sampling and monitoring volcanos. Our robotic exploration technique opens a new era in field techniques for volcano research. Now a robotic machine, under the direction of scientists located in a safe remote location, can slowly and carefully examine and sample the inside of a volcanic crater without jeopardizing human safety. Using its tether cable which is anchored at the crater rim, Dante is able to descend down sheer crater walls in a rappelling-like manner to gather and analyze high temperature gases from the crater floor.

Dante's eight pantographic legs are organized in two groups of four which alternately support and advance the robot. On steep slopes, the tensioned tether cable provides a reactive force to gravity, assists in maintaining equilibrium, and allows Dante to rappel like a mountain climber. Dante can rappel up and down steep slopes and surmount obstacles as large as one meter. Dante receives its power and telemetry through the tether cable, making it an ideal deployment platform for multi-day remote scientific data gathering. A scanning laser rangefinder is used to perceive and model the terrain surrounding the walker. Planning software uses the terrain information to determine safe paths and adjusts the gait to avoid obstacles.

Following Dante's attempt to explore Mount Erebus, Antarctica in January 1993, the NASA Telerobotics Program supported the reconfiguration, development and testing for a summer 1994 mission to Mount Spurr, Alaska. During this mission, which emphasized testing and proving the robot hardware, Dante descended into and explored Crater Peak, the site of recent volcanic eruptions. Dante operated in a self-reliant mode, communicating with an Anchorage base station 130 kilometers distant from the volcano via satellite telemetry. As Dante rappeled down the steep crater walls and explored the crater floor, the robot was controlled and "driven" from the Anchorage base station. Portions of the mission were conducted in a teleoperated mode, meaning that human operators viewed the sensor data (including video cameras), made decisions, and commanded the vehicle accordingly. In addition, we demonstrated autonomous control for certain segments of the exploration mission. From the Anchorage station and two additional "lower 48" stations, viewers (such as students, press and volcanologists) were able to monitor Dante's progress using virtual reality interfaces and graphical workstation displays. In addition, limited robot control capability such as operation of camera and science equipment was possible at the two "lower 48" control stations.

The FY 1995 activity associated with this task included the final funding of the implementation, testing and data collection and analysis of the Dante II field test. These activities were completed in August 1994.

Point of Contact:
John Bares
(412) 268-7091
bares@frc2.frc.ri.cmu.edu