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Robonaut
Robonaut is a humanoid robot designed by the Robot Systems Technology Branch at NASA's Johnson Space Center in a collaborative effort with DARPA. The Robonaut project seeks to develop and demonstrate a robotic system that can function as an EVA astronaut equivalent. Robonaut jumps generations ahead by eliminating the robotic scars (e.g., special robotic grapples and targets) and specialized robotic tools of traditional on-orbit robotics. However, it still keeps the human operator in the control loop through its telepresence control system. Robonaut is designed to be used for "EVA" tasks, i.e., those which were not specifically designed for robots .
Our challenge is to build machines that can help humans work and explore in space. Working side by side with humans, or going where the risks are too great for people, machines like Robonaut will expand our ability for construction and discovery. Central to that effort is a capability we call dexterous manipulation, embodied by an ability to use ones hand to do work, and our challenge has been to build machines with dexterity that exceeds that of a suited astronaut. The resulting robotic system called Robonaut is the product of NASA and DARPA collaboration, supporting the hard work of many JSC Engineers that are determined to meet these goals.
The Shape of Things to Come
We're using a humanoid shape to meet NASA's increasing requirements for Extravehicular Activity (EVA, or spacewalks). Over the past five decades, space flight hardware has been designed for human servicing. Space walks are planned for most of the assembly missions for the International Space Station, and they are a key contingency for resolving on-orbit failures. Combined with our substantial investment in EVA tools, this accumulation of equipment requiring a humanoid shape and an assumed level of human performance presents a unique opportunity for a humanoid system.
While the depth and breadth of human performance is beyond the current state of the art in robotics, NASA targeted the reduced dexterity and performance of a suited astronaut as Robonaut's design goals, specifically using the work envelope, ranges of motion, strength and endurance capabilities of space walking humans. This website describes the design effort forthe entire Robonaut system, including meachanisms, avionics, computational architecture and telepresence control.
Current Robonaut Status
Mechanism Design
The manipulator and dexterous hand have been developed with a substantial investment in mechatronics design. The arm structure has embedded avionics elements within each link, reducing cabling and noise contamination. Unlike some systems, Robonaut uses a chordate approach to data management, bringing all feedback to a central nervous system, where even low-level servo control is performed. This biologically inspired neurological approach is extended to left-right computational symmetry, sensor and power duality and kinematical redundancy, enabling learning and optimization in mechanical, electrical and software forms.
The theory that manufacturing tools caused humans to evolve by requiring skills that could be naturally selected is applied to Robonaut's design as well. The set of EVA tools used by astronauts was the initial design consideration for the system, hence the development of Robonaut's dexterous five-fingered hand and human-scale arm that exceeds the range of motion of even unsuited astronauts. Packaging requirements for the entire system were derived from the geometry of EVA access corridors, such as pathways on the Space Station and airlocks built for humans.
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.

Robonaut

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Introduction:

The requirements for extra-vehicular activity (EVA) on-board the International Space Station (ISS) are expected to be considerable. These maintenance and construction activities are expensive and hazardous. Astronauts must prepare extensively before they may leave the relative safety of the space station, including pre-breathing at space suit air pressure for up to 4 hours. Once outside, the crew person must be extremely cautious to prevent damage to the suit. Certain pieces of the Space Station Alpha have been designed to be serviced by robotic systems. The Canadian Space Agency’s Special Purpose Dexterous Manipulator (SPDM) was developed for this purpose. To be serviceable by the SPDM, worksites have been designed to have different approach corridors than EVA and specialized interfaces.


Robonaut System Overview:

The focus of the Robonaut team has been in the design and construction a dexterous upper extremity. However, Robonaut has recently transitioned from a single hand and arm with a fixed shoulder to a dual limbed upper body with an articulating three degree-of-freedom (DOF) waist. This results in a total of 43 DOF dexterous robot (figure 1). While working during EVA, crew members typically place both legs into a portable foot restraint. In its space configuration, Robonaut uses the same interface with a single seven DOF leg. The end effector’s of this leg uses the same interface as the crew’s foot restraints and plugs into sockets around Space Station. Having a leg provides Robonaut with the ability to anchor itself at worksites and provides a great amount of body mobility once anchored.




Figure 2 shows a representation of Robonaut in its space configuration. Beyond having the correct anatomy to work with EVA equipment, the Robonaut system is designed with space operations in mind. During the design phase, the ability to work in space was considered for nearly every aspect, including materials selection, thermal endurance, lubricants, avionics, and computer selection.


Hands:

Robonaut’s hands set it apart from any previous space manipulator system. These hands can fit into all the same places currently designed for an astronaut’s gloved hand. A key feature of the hand is its palm degree of freedom that allows Robonaut to cup a tool and line up its long axis with the roll degree of freedom of the forearm, thereby, permitting tool use in tight spaces with minimum arm motion.


Brainstem:

The Robonaut control system design philosophy is inspired by the human brain anatomy. The human brain embeds some functions, such as gaits, reactive reflexes and sensing, at a very low level, in the spinal cord or nerves. Higher functions, such as cognition and planning take place in other parts of the brain.