PITTSBURGHˇA prototype solar-powered robot with the potential to be self-sufficient for extended periods of time will be tested in the Canadian Arctic by Carnegie Mellon University researchers in July. The researchers will test a concept called Sun-Synchronous Navigation that may enable autonomous robots to obtain continuous solar power for long-term exploration of distant planets and moons. The robot named Hyperion was developed by researchers at Carnegie Mellon's Robotics Institute with support from NASA. It represents the latest in a series of terrestrial testbeds for planetary explorers the institute has developed for NASA in a relationship that spans more than a decade. (see attachment).
Several weeks of experiments will be conducted to measure the robot's performance and test computer algorithms, building up to integrated experiments that will take place over 24-hour periods of continuous sunlight.
Sun-Synchronous Navigation is a technique that involves tracking the sun while exploring terrain. It's accomplished by traveling opposite to planetary rotation and in synchrony with the sun. The robot must reason about its position and orientation with respect to the sun while it explores its surroundings. It navigates to capture enough sunlight to power itself while traveling through rough terrain and trying to reach important scientific objectives.
Researchers believe that at the right latitude and speed, robotic explorers should get enough sunlight to maintain continuous operation. For some missions, by following the dawn, these rovers may also be able to regulate their temperatures by staying in the transition region between frigid night and scorching daytime temperatures. They would travel with the sunrise and never have to hibernate overnight. The performance of almost any mission would be improved by deliberately choosing where to park and orient themselves to maximize power from the sun.
"Near the poles of the moon, the idea is for a robot to move with the dawn, and always remain in sunlight as explores its environment," said Robotics Institute Research Scientist David Wettergreen, a co-investigator on the project. "In northern Canada, Hyperion will explore in a circular pattern as the sun circles the sky. Robots could employ a similar strategy in the polar region of Mars."
"Sun-synchronous navigation would enable robots to undertake missions of months or years," said principal investigator William L. "Red" Whittaker, Carnegie Mellon's Fredkin research professor and a pioneer in the development of mobile robots. "To travel vast distances on the moon or Mars is what is called for to make the revolutionary discoveries. The trend is also to explore ever more difficult terrain where scientific information is richest."
"This will enable us to develop rovers with much less complexity because they won't have to withstand extremes in temperature," said Melvin Montemerlo, NASA program executive, Office of Space Science, Washington, DC.
Hyperion is named for a Titan of Greek mythology who fathered the sun, moon and the dawn. The word Hyperion roughly translates to "he who follows the sun."
Hyperion is 2 meters long, 2 meters wide and almost 3 meters tall with a near vertically mounted solar panel measuring 3.5 square meters. It carries this panel mounted upright to catch the low-angle sunlight of the polar regions. Hyperion operates on about 200 watts of power. It is fabricated of aluminum tubing and has four wheels on two axles. On the front axle, a frame supports stereo cameras and a laser scanner. All of Hyperion's computers, electronics and batteries are mounted in a body enclosure between the axles. The robot weighs 156 kilograms.
Wettergreen said Hyperion can act autonomously by combining sun seeking algorithms with those that sense the terrain and avoid obstacles. It also has enough intelligence to know when it is lost or in trouble and can send a message to human operators to ask for help. It shifts smoothly from autonomous mode to being tele-operated.
Hyperion is a concept vehicle designed to operate only on Earth. Robots designed for flight missions would require specialized components, such as space-qualified motors and computers, and mission specific scaling of items like the solar panels. The field experiments with Hyperion will take place on the hilly, rock-strewn terrain of Devon Island, Nunavut, Canada, the largest uninhabited island in the world and site of the Haughton Crater. Since 1996, Devon Island and the crater area have been used by researchers working on the NASA/SETI Haughton-Mars Project, an international field research program, which studies the crater and its surroundings as an analog of Mars.
Wettergreen will lead the field experiment with six colleagues, including Robotics Institute engineers and graduate students. They intend to verify the algorithms they've developed and validate the parameters that will allow sun-synchronous explorers to be developed for other planets.
The Carnegie Mellon team leaves for Devon Island on July 3. Experiments will begin around July 10 and conclude by July 20. There is a narrow window of time to conduct the experimentsˇafter the snow has melted in mid-July and when the sun begins to drop below surrounding hills toward the end of the month. The team intends to produce status reports, images and online movies throughout the field experiment.
To follow the Sun-Synchronous Navigation Project and learn more about Hyperion, see http://www.frc.ri.cmu.edu/sunsync/. More details on the NASA/SETI Haughton-Mars Project can be found at http://www.arctic-mars.org. For more information about Carnegie Mellon's Robotics Institute, see: http://www.ri.cmu.edu.
Don Savage or Dolores Beasley, NASA headquarters
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