How Robonauts Work

Robotic probes and rovers have been traveling toMarssince before we landed on the moon. In 1965,Mariner IVsent back the first close-range images of the red planet. In 1997, thePathfinderroverprovided unprecedented detail on the Martian atmosphere and surface. Moreover, who can forget the remarkable contributions ofSpiritandOpportunity, the two Mars rovers launched in summer of 2003 that so outlasted their original mission?

NASA has based its robotic astronauts on a humanoid design. The first of these,Robonaut 1(akaR1), featured a head, two eyes, two arms and two five-digit hands. Designers protected R1's head with an epoxy-resin helmet and mounted the head on a jointed neck, which permitted it to turn from side to side and to look up and down. Within the pioneering robonaut, two video cameras deliveredstereovisionto the operator and enabled R1 to track objects. Stereovision mimics human vision by comparing images from a right and left "eye" (camera) and usingparallax-- the apparent difference in an object's position caused by the different viewing angle of each eye -- to determine depth and detect motion. R1's arms were capable of a greater range of motion than human arms and packed more than 150 sensors each.

NASA began construction of R1 in 1997, and it served as an experimental platform in laboratory and field tests until 2006. It was a successful proof of concept, but it never left the lab.

In 2006, NASA signed an agreement with General Motors to produceRobonaut 2(R2). GM was also developing dexterous robots at the time and had worked with NASA on the lunar rover. NASA unveiled R2 in February 2010, and the robonaut traveled to its permanent home on the International Space Station Feb. 24, 2011, on one of the final space shuttle missions.

Like R1, R2 is designed to help humans and to automate repetitious, dull or tiring tasks -- such as setting up the tools and equipment necessary for missions -- freeingastronautsto concentrate on tasks that only they are qualified to perform.

Think of R2 as R1-plus -- smaller, cheaper, more advanced and capable of surviving the rigors of launch and of space. R2 delivers more than 350 sensors, 40 of which it uses to detect its surroundings. That includes four visible-light cameras in its eyes and a fifth infrared camera in its mouth to aid in depth perception. Its stomach contains 38 computer processors. Although its strength is on par with R1's -- it can lift around 20 pounds (9 kilograms) -- R2 is more adept with its handy appendages: Whereas R1's hands were akin to an astronaut's gloved hands, R2's are more like ungloved human hands.

R2 can manipulate a blanket, pick up an envelope and grip a dumbbell, but its dexterity is greater than the sum of its parts. Users can control R2's joint stiffness, which gives R2 a leg up over typical "positionally controlled"robotslike automobile assembly robots, which lack "give" in their systems and must line up perfectly to do their job. Such a robot would be lousy at putting a peg in a hole; even a slight misalignment would cause it to smash the peg into the area around the hole. R2, conversely, can "feel" its way home, moving the peg softly forward and making small, sliding corrections if misaligned, like a human would. R2's flexibility also makes it safer for its human companions, who can stop its motion without much force, thereby avoiding injury.

Here are the specifications for Robonaut 1 and 2:

Specifications	Robonaut 1	Robonaut 2
Height	6.23 feet (1.9 meters)	3.33 feet (1.0 meters) (waist to head)
Weight	410 pounds (182 kilograms)	330 pounds (150 kilograms)
Structural Materials	Mostly aluminum with Kevlar and Teflon padding to protect it from fire and debris	Primarily aluminum with steel, nickel-plated carbon fiber and nonmetallics
Computing Platform	PowerPC processor	38 PowerPC processors
Operating System	VxWorks	VxWorks

Beyond NASA Whatever the future of robonauts, the competition is heating up like a shuttle on re-entry. The European Space Agency is updating its Eurobot with four wheels, two arms, interchangeable hands with tools, an advanced navigation system, cameras and sensors. The agency is also considering partially transforming robots, such as a rover with wheels that become feet. China hopes to send an unmanned rover to the moon by 2012 and launch a robotic mission to bring back samples by 2017. Japan has said that it wants to put a bipedal robot on the moon by 2015 and build a moon base by 2030.

Robonaut 2 (R2), like its predecessor, is controlled using telepresence, in which a person -- either an astronaut or an operator at mission control -- guides the robot remotely while seeing through its eyes via onboard cameras. The operator can wear gloves to operate R2's hands, or control R2's head motions by wearing ahelmetremotely linked to the robot's head.

R2 is no mere puppet, however. Like the Mars rovers, the robonaut also operates under supervised autonomy, which means it comes loaded with sequences of commands (scripts) that tell it how to perform certain tasks autonomously. An operator monitors its progress during these actions and can make corrections as necessary in real time. The hope is that R2 will one day graduate from robo-trainee to robo-employee and require very little observation or direction.

Like R1, R2's brains consist of a series of PowerPC processors -- a technology used in other space applications -- running the VxWorks real-timeoperating system. NASA says that this combination offers flexible computing and supports varied development activities. The system software is written inC and C++. ControlShell software aids the development process and provides a graphical development environment, which enhances researchers' understanding of the system and code.

Initially, R2 will be confined to a lab on the International Space Station. There, it will run tests using a series of boards with switches, knobs and connectors like the ones the astronauts operate. Engineers on the ground will send hardware and software updates as needed. Eventually, R2 will be equipped with a leg or legs complete with toes that fit toeholds built into the station's walls, which will enable R2 to climb while leaving its hands free to carry equipment or perform tasks.

Eventually, R2 will receive extravehicular activity (EVA) equipment and will be able to go on spacewalks outside the station. It will then be able to set up work sites and reduce the time humans must spend outside. Because it can transition much more quickly to the exterior thanastronauts, R2 will be able to respond to emergencies as well.NASAis working on a battery (currently R2 has to be plugged in) to increase the R2's range, and future robonauts could be outfitted with wheels or even a jetpack for exploratory and maintenance missions. Nor will dexterous robots like R2 be limited to exploring space: One day, they might enter hazardous locations on Earth in place of humans, like volcanoes andnuclearplants.

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