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Hyperion
Hyperion Photo

Hyperion is a solar-powered robot designed for exploration in barren terrain. The name Hyperion comes from Greek mythology: Hyperion was a Titan, a predecessor to the Gods, who in myth fathered the Sun, Moon and dawn. The word Hyperion roughly translates to "he who follows the Sun" and is certainly descriptive of a solar powered robot that reasons about its resources and tracks the sun to optimize energy. Hyperion is now being used as a testbed for software and hardware that will be on the new robot, ZoŽ.

Characteristics Navcam Views
Height 1.5m
Width 2m
Length 2m
Weight 156kg
Top Speed 30 cm/s
Turning Radius 2.5m
Odometer 100km
Navcam Left Image Navcam Right Image
Panoramic Image
Salar Grande Panorama Thumbnail
View of Salar Grande as seen by Hyperion's cameras (1.04MB).

FAQ

What does Hyperion look like?
Hyperion is two meters long and two meters wide with a panel of silicon solar cells of 3.5 square meters. It can be configured for polar or equatorial operation. In polar regions it carries its solar array near vertically to catch the low-angle sunlight; when operating closer to the equator its panel lays flat in a level deck for the sun overhead. Hyperion is fabricated of lightweight aluminum tubing and has four wheels on two axles. On the front axle an A-frame stands 1.5 meters high to support the stereo cameras and laser scanner at a proper height to see the surrounding terrain. All of Hyperion’s computers, electronics and batteries are enclosed in a single body mounted between the axles. The robot weighs 156 kilograms.

How does Hyperion drive and steer?
Hyperion is driven by four motors, one for each wheel. It has a passive (unactuated) joint at the front axle that can roll and yaw relative to the back end—similar to a wagon. It steers by driving the wheels at different speeds but instead of skidding like a bulldozer, the passive joint turns and the robot smoothly follows arcs. The advantage of this design is that the number of actuators is minimized (there are only four motors) but energy is not wasted skidding the wheels when turning.

What sensors does Hyperion use?
Hyperion uses a pair of digital cameras to image the terrain in front of it and a laser line scanner to detect close in obstacles. It carries a third camera that can produce panoramic images so that remote observers can view its complete surroundings. Hyperion’s laser scanner sweeps a line in front of it looking for obstacles, either rocks or drop-offs. Hyperion measures speed, voltage and current on all its motors so that it can monitor their performance and determine its motion. It has roll and pitch inclinometers for determining motions. The robot has numerous sensors to monitor power generation and consumption. There are temperature sensors spread throughout to monitor critical components.

How is Hyperion powered?
All of Hyperion’s energy comes from the sun. Its solar cells supply its power bus, which runs computers and sensors, drives the wheels and charges batteries. The output of the solar panels depends on the solar flux which is a function of the orientation of the panel and atmospheric conditions. The overall power tracking system is 11% efficient so if 600 W/m2 of solar energy (a typical value) falls on the 3.5m2 panels then Hyperion will have about 200W to use. Any excess power is put into a bank of lead-acid batteries so that Hyperion has capacity to climb a steep slope, drive over an obstacle, or take a shortcut through a shadow or away from the sun when necessary. It’s battery capacity is 32Ahr at 24V.

How does Hyperion avoid shadows and know where to go?
Hyperion operates sun-synchronously, meaning it tracks the sun and determines its actions to maintain sufficient power to complete its mission. To navigate Hyperion must have a map of the terrain, an estimate of where it is located, and a measurement of the current time. Digital elevation maps at 100m resolution or better are available for most of the Earth. Maps of this resolution or better are, or will soon be, available for interesting areas of the Moon and Mars. Hyperion uses a combination of inertial sensing and odometry to determine its location and an accurate onboard clock to know the current time. With a map and a clock Hyperion can determine the relationship between the sun and terrain to compute where shadows will fall. By knowing its location relative to the map it can determine where the shadows are and how they will move over time. The difficult problem is then to make decisions that optimize the efficiency and safety of the path while reconciling the need to maintain adequate power all the time.

How does Hyperion avoid obstacles like rocks and slopes?
To travel through terrain Hyperion uses a pair of cameras, like eyes, and computer algorithms to see, measure and model obstacles in its immediate surroundings. It then evaluates multiple possible paths that avoid the obstacles, selecting a path that heads toward its goal while collecting sufficient solar energy to proceed. Hyperion can miss seeing an obstacle under certain conditions so it also carries a laser scanner to act as a “virtual bumper”. If something, like a dirt-covered rock, appears in front of it, Hyperion stops immediately and sends a message indicating that it has been surprised and may have a problem.

Is Hyperion autonomous?
The answer is sometimes yes and sometimes no. Hyperion’s control system is designed for what is sometimes called “sliding autonomy.” It can smoothly slide from direct teleoperation where a human operator tells it everything to do, through modes of control where the operator and robot share decision making, to full autonomy where Hyperion decides for itself how to perform a given mission, where to go and when. Hyperion has a health monitoring capability that enables it to decide when it needs help. If it can’t find it’s way, thinks the mission is impossible, or detects strange behavior from its sensors, it sends a message to human operators about what has happened and if it has decided to stop and wait for instructions. When everything is okay it can decide to pick up and continue on its own.

How will Hyperion explore?
Hyperion must move with the sun to collect the energy that it needs to survive. As it explores it can conduct science investigations on the fly, collecting data and seeking evidence of specific phenomena: biological, hydrological or geological, while it is traveling. Exploration is complicated by the sometimes conflicting goals of scientific interest and power consumption but ultimately the advantage is that Hyperion can cover great distances and survive for a long time. In exploration both of these factors increase the chance of finding something interesting.

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  • Devon Island Expedition 2000
  • Atacama Desert Expedition 2002

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