ANN ARBOR---Without signposts in the open ocean or a reliable way to take reference points from the stars, ancient mariners navigated by what is known as "dead reckoning," figuring out where you are by mapping the distance and direction you've traveled.
An innovative new robot developed by the Mobile Robotics Lab at the University of Michigan navigates the same way. Rather than using sensors to detect signposts along its path or following a wire in the floor, the OmniMate uses very precise odometers on four of its 12 wheels to figure distance and direction.
The OmniMate is sort of a smart pallet, supporting a flat 3-foot-by-6-foot platform on its back. "The current model can carry 250 pounds, but the next-generation OmniMate could handle up to 1,000," Johann Borenstein said.
"Any production plant that needs to move materials can use the OmniMate," he added. "Specifically in our area, the three big car makers would be interested." One OmniMate is currently being tested at the NSF Engineering Research Center for Reconfigurable Machining Systems at the U-M.
OmniMate comes from a family of robots known as Automated Guided Vehicles, or AGVs. Unlike most existing AGVs, however, OmniMate can move in any direction including sideways, diagonally, or rotating on the spot.
The existing AGVs can be confused by traveling over bumps or slick spots on the floor. So they rely on beacons, markers, or guide-wires in the environment to maintain their bearings. But those kinds of systems add cost and installation problems to the robotic system. OmniMate should be able to overcome those requirements with its superior navigation, and will be simpler and cheaper to operate because it won't require installation of all the guidewires and beacons, Borenstein said.
The robot features a several new devices which set it apart from earlier AGVs.
--A patented "compliant linkage" prevents excessive wheel slippage during maneuvers. This device also ensures that OmniMate's dead-reckoning odometers are not misled by bumps or slick spots on the floor.
--A patented "Internal Position Error Correction" system checks odometer readings from four of the wheels against each other.
--A fiber-optic gyroscope helps the OmniMate stay on course over extended distances.
"As a result, the OmniMate's dead-reckoning is almost completely insensitive to even severe bumps, cracks, or low obstacles on the floor," Borenstein said.
Because of its extraordinary dead-reckoning accuracy, the OmniMate can negotiate long, pre-programmed paths fully automatically. And the programming is quite simple. The U-M researchers have developed a "lead-through" teaching system which uses a joystick device. An operator guides the OmniMate along a desired path only once while the OmniMate commits its movements to memory. Then, the robot can follow the path accurately by itself. Changing its path takes only a few minutes.
Helpmate Robotics Inc. of Danbury, Conn., co-developer of the OmniMate, has already manufactured three commercial prototypes of the system.
Borenstein, an associate research scientist in the U-M's Department of Mechanical Engineering and Applied Mechanics, won Discover magazine's 1998 Discover Award, in the robotics category, for his invention, the GuideCane, a robotic walking stick for the blind. The awards honor "men and women whose creative genius improves the quality of our everyday life and alerts us to what's next from the frontiers of human achievement and ingenuity."
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EDITORS: For a photo and schematic of the robot, visit Borenstein's lab on the Web: http://www-personal.engin.umich.edu/~johannb/OmniMate_News/OmniMate_News_Release.html
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