The challenges of extra-vehicular robotic locomotion aboard orbiting spacecraft

NASA´s Human Space Flight program depends heavily on spacewalks performed by human astronauts. These Extra-Vehicular Activities (EVAs) are risky, expensive and complex. In collaboration with the Defense Advanced Research Projects Agency (DARPA), NASA is developing a robotic astronaut´s assistant called Robonaut that can boost EVA productivity and help conserve human EVA hours. Robonaut is an anthropomorphic robot equipped with human-like dexterous manipulation and zero-g locomotion capabilities. In order to move about in a zero-g environment, a robot must be able to climb autonomously, using gaits that smoothly manage its momentum and that minimize contact forces while providing for safety in the event of an emergency requiring the system to stop. All three of these objectives are now being explored at NASA´s Johnson Space Center with computer analysis and visualization tools as well as hardware tests involving the Robonaut system and a set of facilities and mockups that emulate the zero-g condition.