Monday, September 17, 2012

How the Curiosity rover's robotic arm is blazing a trail on Mars ... and Earth

Ashitey Trebi-Olennu is one of the engineers behind the robotic arm system on NASA's Curiosity rover. He has also been a rover planner for the Spirit and Opportunity rovers, and worked on the robotic arm system for the Phoenix Mars Lander.

The robotic arm on NASA's Curiosity rover should set a new standard for robotic operations on Mars — and it could revolutionize robotics on Earth as well.

At least that's what Ashítey Trebi-Ollennu, one of the four robotic-arm system engineers on the Mars Science Laboratory team, is looking forward to. He expects the features developed for Curiosity's 7-foot-long (2.1-meter-long) robotic arm to show up on a planet near you in the form of NASA-enabled technologies, or NETs.

"Anytime I see a technology, I say to myself, 'Is this a NET?'" he told me last week.

The robotic arm cleared the last of its commissioning tests last Thursday, and is now ready for duty on Gale Crater. Just based on metrics alone, Curiosity's arm is in a class by itself: It's twice as long as the arm that was installed on the Spirit and Opportunity rovers, and is tipped with a turnable, twistable turret that weighs 30 kilograms (66 pounds), or about as much as a small child.

That turret is bristling with instruments — including an X-ray spectrometer, a fine-resolution camera, a scoop and some sifters, a dust-sweeping brush, and a percussive drill that can smash rock to bits for analysis in the rover's onboard chemistry labs. The arm is designed to press that drill against the rock with a force of 300 newtons (67 pounds), which is more of a push than a construction worker generally uses for overhead drilling on Earth.

It's a formidable machine, which has to be managed with care from a distance of 175 million miles (282 million kilometers). "You can do a lot of damage if you don't take precautions," Trebi-Ollennu said. "You could damage a camera on the mast, you could damage instruments on the turret, you could run it into the ground."

That's what he and his colleagues on the robotic-arm team at NASA's Jet Propulsion Laboratory have been working to avoid: They tested all the sequences the arm is expected to run in advance, in simulations and a robotic test bed. Now the same tests have been run on the actual rover. There were no surprises on Earth, and no surprises so far on Mars, either.
Curiosity's robotic arm rises above the Martian landscape in a picture taken by the robot's navigation camera.
Earthly applications
The fact that robotic operations can be conducted so smoothly from so far away is a good sign for telerobotics on Earth, Trebi-Ollennu said. He foresees a day when a "factory in a can" could be delivered to a remote location — say, a nuclear cleanup site in Japan or an oil spill in the depths of the Gulf of Mexico — and go about its business as if humans were on the scene.

"You could have somebody several thousand miles away and operate this factory in a can remotely," Trebi-Ollennu said. "If you have a factory in the can, you can have the level of penetration that you have with cellphones today."

Another innovation comes in the form of the titanium arm's pushing power. "You want to have a running back with the power of a linebacker," said Trebi-Olennu, adapting a football-team comparision. "You want to get 300 newtons, but you want to get it in a small package."

Advantageous weight-to-power ratios come in handy for robotic applications on Earth as well as Mars. "We are trying to design systems that can 'push' above their weight, and at the same time not break," Trebi-Olennu said.

Another innovation with potential earthly applications is the rover's array of piezoelectric actuators, which use electrical impulses to shake powdered rock and soil out of its sampling containers and into its SAM and CheMin laboratories. "These have the potential of having a very big impact in the pharmaceutical industry," Trebi-Olennu said.

The technology underlying the actuators was co-developed by JPL and Cybersonics, and it's already being used in Cybersonics' CyberWand medical equipment. The CyberWand dual-action lithotripter simultaneously applies ultrasound and a "jackhammer" action to pulverize bladder stones and suck away the dust.

Global reach
Trebi-Ollennu, who was born in Ghana and trained as an engineer in Britain and the United States, says telerobotics will eventually make the world seem smaller. Specialists based at the world's best medical centers will be able to direct operations in faraway locations, and manufacturers will be able to place mobile robotic factories closer to the source of the raw materials they require.

This vision isn't the nightmare of robots from another planet invading Earth. Rather, it's the dream of humans and robots working together, using technology initially developed for another planet, to make our own world better. Someday, maybe that technology will help us settle other worlds as well.

"It's such a robust system that you can get the robot to do what the robot is good at doing, and you have the human doing what the human is good at doing," Trebi-Ollennu said. "You have a strong package."

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