Space Walking Robots - Robonaut

Sensors and Telepresence Control

Robonaut's broad mix of sensors includes thermal, position, tactile, force and torque instrumentation, with over 150 sensors per arm. The control system for Robonaut includes an onboard, real time CPU with miniature data acquisition and power management in a small, environmentally hardened body. Off-board guidance is delivered with human supervision using a telepresence control station with human tracking.

Meeting the needs

To meet the dexterous manipulation needs foreseen in future NASA missions, the Automation, Robotics, and Simulation Division at Johnson Space Center is developing Robonaut, a highly dexterous anthropomorphic robotic system. Robonaut is advancing the state of the art in anthropomorphic robotic systems, multiple use tool handling end effectors, modular robotic systems components and telepresence control systems. The project has adopted the design concept of an anthropomorphic robot the size of an astronaut in a space suit and configured with two arms, two five-fingered hands, a head and a torso. Its dexterous pair of arms enables dual-arm operations and its hands can interface directly with a wide range of interfaces without special tooling. Its anthropomorphic design enables intuitive telepresence control by a human operator.

Head

Robonaut's head is still a work in progress, but the existing system includes an articulated neck that allows the teleoperator to point Robonaut's face. The head holds two small color cameras that deliver stereo vision to the operator's helmet display, yielding a form of depth perception. The interocular spacing of the cameras is matched to typical human eye spacing, with a fix vergence at arm's reach. The neck drives are commanded using a 6 axis Polhemus sensor mounted on the

NASA The operator can see through two cameras in Robonauts' head

teleoperator's helmet, and can track the velocities of typical human neck motions. Like the arms, the neck's endoskeleton is covered in a fabric skin, which is fitted into and under the helmet. The helmeted approach is unusual in the robotics world, where cameras are typically mounted in exposed locations on pan-tilt-verge units. Robonaut's requirements for a rugged design, working with astronauts in cluttered environments drove the design towards a better protection system, such as the helmets that humans where here on Earth. The helmet is made of an epoxy resin, "grown" using a stereo lithography machine at the Johnson space center. As you can see, the design was inspired by Centurian armor, giving Robonaut some attitude. The neck joints are similar to the joints and are controlled with the same real-time control system. Their kinematics is based on a pan-tilt serial chain, with the first rotation about Robonaut's spine, and then a pitch motion about a lateral axis. The pitch motion axis does not pass through the camera sensors, but is instead 3 inches below, like the Atlas joint in the human neck. This offset (actually a D-H link length) allows the cameras to translate forward, letting Robonaut see down over its chest.