Human-like hands, fingers and even television camera eyes have been hallmarks of NASA's Robonaut, but recent work seeks to give the nimble robot legs, or at least a leg, and even wheels.
Robonaut took its first steps recently during tests at the Johnson Space Center in Houston, using a single "space leg" to move around the outside of a simulated Space Station. Other recent tests put the humanoid robot on wheels, a Segway scooter to be exact, and let it take to the road.
In either configuration, Robonaut's head, torso, mechanical arms and hands maintain their ability to use the same space tools as humans. In the tests using its "space leg," Robonaut commuted like a futuristic construction worker hand-over-hand outside a mock spacecraft. Aboard the gryo-stabilized wheels, it glided from one test station to another as its descendants might someday on the surface of the Moon or Mars.
Tests with the leg confirmed that Robonaut could climb around the outside of a spacecraft using handholds and plant its foot at a work site to make repairs or install parts. NASA's goal is to build robots that could 'live' on the outside of spacecraft, ready for routine maintenance or emergencies. Humans inside the spacecraft would operate Robonaut with wireless controls.
The wheeled tests provided initial proof of concept for planetary Centaurs that merge humanoid robots with rovers. Those tests put Robonaut through its paces while mounted on a Segway Robotic Mobility Platform. They showed that a single teleoperator could simultaneously control both the robot's mobility and dexterity with a wireless control system.
The climbing tests were a significant step in Robonaut's development, proving the system's capability for climbing, stabilizing and handling extravehicular activity (EVA) tools and interfaces in the space environment. The test featured a battery-powered, wireless Robonaut system mounted to an air-bearing sled, floating on a cushion of air, to eliminate friction and emulate the sensations experienced by astronauts working in zero gravity. Robonaut climbed using EVA handrails and plugged its stabilizing 'space leg' into a standard space station WIF (Worksite Interface Fixture) socket, while its operators drove Robonaut's multiple limbs using innovative new telepresence controls.
"This test proved Robonaut can be operated wirelessly using an interchangeable base for different stabilization and locomotion systems -- and it did it in a frictionless, space-like environment," said Test Conductor Dr. Robert Ambrose of JSC's Automation, Robotics and Simulation Division. "These are all key capabilities needed for the development of future 'EVA squads' that leverage the combined talents of humans and robots to make vast improvements in spacewalk productivity."
The Robonaut Project, which Ambrose leads, is a collaborative effort with the Defense Advanced Research Projects Agency (DARPA), and has been under development at JSC for several years. There are two Robonauts, each with highly dexterous hands that can work with the same tools humans use. Operators remotely control movements of the Robonauts' heads, limbs, hands and twin cameras through a combination of virtual-reality interfaces and verbal commands, relayed either through dedicated cabling or wireless systems.
In order to move about in a zero-gravity environment, a robot must be able to climb by itself, using gaits that smoothly manage its momentum and that minimize contact forces while providing for safety in the event of an emergency. To access worksites aboard the International Space Station and future spacecraft, robots must interact with spacewalking aids designed for humans including tethers, handrails and work anchors.
"The tests were very successful," Ambrose said. "The Robonaut team learned which climbing maneuvers are more feasible than others, and tested automated software safety reactions using the robot's built-in force sensors. We also identified new opportunities for using these sensors in semi-automatic modes that will help operators across short (1-10 second) time delays. Our team will continue to tackle these challenges as NASA looks forward to applying human-robotic interaction to the tasks associated with returning to the Moon and going on to Mars."
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