Saturday, July 25, 2009

Creating 'service robots'

Since human beings began to imagine robots - and the beginning was a 1920 Czech play called Rossum's Universal Robots, in which, yes, the machines do end up as our steely overlords - we've imagined them as mechanical, though perhaps more powerful, versions of ourselves.

Think of Maria from Fritz Lang's "Metropolis," Gort from "The Day the Earth Stood Still," C-3PO from "Star Wars," or the Terminator.

"It's very far from reality," said Ranjan Mukherjee, a professor of mechanical engineering at Michigan State University. "Human beings are very complex and making robots that are like human beings is not easy."

He knows what he's talking about. Mukherjee has received $247,000 in federal stimulus money to develop technology that could, among other things, allow two-legged robots to move more like humans: to climb stairs, walk on uneven ground, maybe even jump, tasks that even the most advanced robots can't do particularly well.

But, if everyday service robots are to become a reality, and Mukherjee believes they will, they will have to be able to operate in environments designed for humans. Meaning they should probably be able to handle the stairs.

"Most of the people working on bipeds" - that is, robots with two legs - "design them to walk on a flat surface," Mukherjee said. "Very few bipeds can climb stairs. We take that as the first challenge. Eventually, we would like to get to the point where it can handle undulated surfaces, uneven surfaces."

Consider the force
The reason robots aren't good with such surfaces has a lot to do with the way their movement is powered.

Most have motors that drive their movement that are along the lines of those that power electric fans. The power can be stronger or weaker, but it's more or less continuous.

What robots generally can't do is apply what are called impulsive forces: short, strong bursts of power that could allow them to make quick corrections when their balance shifts or when they encounter unexpected changes in terrain.

Humans do this all the time. When we jump from a height, for example, our muscles fire quick bursts of power that keep us from falling on our faces when we land.

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