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Wednesday, 4 May 2011

Mobile Robots

Robotic arms are relatively easy to build and program because they only operate within a confined area. Things get a bit trickier when you send a robot out into the world.

NASA's FIDO rover
Photo courtesy NASA
NASA's FIDO Rover is designed for exploration on Mars.

The first obstacle is to give the robot a working locomotion system. If the robot will only need to move over smooth ground, wheels or tracks are the best option. Wheels and tracks can also work on rougher terrain if they are big enough. But robot designers often look to legs instead, because they are more adaptable. Building legged robots also helps researchers understand natural locomotion -- it's a useful exercise in biological research.

Fujitsu's HOAP-1 robot
Photo courtesy Fujitsu and K&D Technology, Inc.
Fujitsu's HOAP-1 robot

Typically, hydraulic or pneumatic pistons move robot legs back and forth. The pistons attach to different leg segments just like muscles attach to different bones. It's a real trick getting all these pistons to work together properly. As a baby, your brain had to figure out exactly the right combination of muscle contractions to walk upright without falling over. Similarly, a robot designer has to figure out the right combination of piston movements involved in walking and program this information into the robot's computer. Many mobile robots have a built-in balance system (a collection of gyroscopes, for example) that tells the computer when it needs to correct its movements.

NASA's Frogbot
Photo courtesy NASA
NASA's Frogbot uses springs, linkages and motors to hop from place to place.