How Robonaut 2 Will Help Astronauts In Space

POSTED BY: ERICO GUIZZO  /  WED, FEBRUARY 23, 2011

Tomorrow is a huge day for robotkind. If all goes as planned, at 4:50 p.m. EST, the space shuttle Discovery will blast off from Cape Canaveral, Florida, carrying aboard a crew of astronauts and also NASA's Robonaut 2, which will become the first humanoid robot in space.

The shuttle's destination is the International Space Station, ISS, where Robonaut 2 will become a permanent resident and work alongside humans as a robotic helper. Astronauts will mount the robot on a fixed pedestal inside one of the ISS labs and use it to perform tasks like flipping switches and holding tools.

So no, Robonaut won't be fixing meals for the human crew. The main goal is to find out how manipulation robots behave in space -- and also give crew members a second pair of hands. NASA hopes the experience will allow it to upgrade the robot in the future, so it would be able to support astronauts in more complex tasks, including repairs and scientific missions outside the ISS.

The robot can perform tasks autonomously or under remote control, or a mix of both, Nic Radford, the Robonaut deputy project manager, told us. Astronauts on the station will operate the robot using a laptop, he said, though it can also be "joysticked" and directly controlled from Earth, with a few seconds of delay.

Sending Robonaut to space is a great feat for NASA, but it raises the question: Is this another step in using robots to replace humans in space exploration? In my opinion, using teleoperated and semi-autonomous robots makes a lot of sense. Robotic explorers have already demonstrated that unmanned missions offer formidable rewards, with immensely smaller costs and risks than manned ones. Of course, NASA enjoys cheering for its robots, but it's quick to point out that robots are not a replacement for humans in space, but rather "companions that can carry out key supporting roles."

That might be the case for now, as robots still can't match human manipulation and other capabilities. But robots are catching up fast. One of Robonaut 2's key features is its dexterous, humanlike arms and hands. Each arm is about 80 cm [31 in] long and can hold 9 kg [20 lb] in Earth's gravity. Each hand has 12 degrees of freedom: 4 DOFs in the thumb, 3 DOFs in both the index and middle fingers, and 1 DOF in the other fingers. The fingers are articulated and driven by tendons, just like human hands, and Robonaut is able to use the same tools that human astronauts use.

NASA developed the robot in a joint project with General Motors. The goal was to build a robotic assistant that could work side by side with humans, whether they are astronauts in space or workers at GM manufacturing plants on Earth.

At the IEEE Humanoids conference last December, I spoke with GM researcher Muhammad E. Abdallah, who explained how Robonaut's hands work:

The Robonaut's hands work a bit differently than similar humanlike robot hands. Existing tendon-driven robotic fingers typically control their joints using tension controllers on each tendon. In other words, desired joint torques are translated into desired tendon tensions. The problem is that, in this approach, there's a coupling between the tendon and joint displacement that re

ults in disturbances in the movement of the fingers. NASA and GM engineers solved the problem by implementing a joint-based torque control method. It decouples the tendon effects and is faster and more reliable than traditional methods.

The ability to control torque is important for Robonaut, and other humanoid robots, for that matter, because its hands will interact with unexpected objects or items slightly out of position. Industrial robots, by contrast, interact with known objects in well-defined spaces. Robonaut's hands mimic human hands in their ability to adapt to variation -- a capability that NASA demonstrated by having different people shake hands with the robot.

But the robot is more than just arms and hands, of course. Robonaut 2 weighs in at 150 kg [300 lbs] and if you're wondering, it has no legs -- it will remain stationary inside the ISS, although NASA researchers have been experimenting with robotic legs and wheels. Built primarily with aluminum with steel parts, it carries over 350 sensors and has a total of 42 degrees of freedom.

In a second phase of the Robonaut project, at an undecided date, NASA will be making the unit mobile using a leg-type system, giving it the ability to move around inside the ISS. The third phase will feature a robot that will perform missions outside the space station. Robonaut is also a part of Project M, which wants to put a humanoid robot on the moon in 1,000 days -- beating Japan’s proposed goal of 2015.

For now, all eyes will be locked on the space shuttle at Cape Canaveral. It's been a long wait for this launch. And once Robonaut arrives at the ISS, it might take several months until astronauts unpack it and bring it to life. Still, I find the idea of a robot in space -- a staple of science fiction -- truly exciting. What do you think? Is this the beginning of a new era in robotic space exploration?

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