10 March 2007

Salamander Robots, Headless Chickens, Aimless People


Have you ever wondered how a chicken can continue to run around without its head? An animal's spinal cord is capable of much more control than most people realize. By understanding how the spinal cord controls rhythmic muscle movements, scientists are learning how to teach salamander robots to walk.
....choreographing robots designed to walk, swim, or run is a tougher task [ed.: compared to robots on wheels].

"Every time a foot hits or leaves the ground, the dynamics change," says Anthony Lewis, president of a company called Iguana Robotics in Illinois, US. "The standard methods that engineers use have a really hard time with this," because the calculations rapidly become very complex.

So some robotics researchers are starting to mimic biology. In animals, the mechanics of walking, swimming, running, and crawling are all coordinated by clusters of neurons in the spinal cord, called central pattern generators. These CPGs produce neural pulses that drive different muscles so that they contract rhythmically in a manner that produces running or walking motion, depending on the pattern of pulses.
Franken-salamander

This basic coordination does not require the brain, which is why a chicken can run around even after its head has been removed. However, simple signals from the brain can instruct the CPG to switch between different modes, from standing still to swimming or walking.

While roboticists would like to emulate this smooth transition between movements, biologists are starting to decipher the way it works. By removing most of a salamander's brain and stimulating the spinal cord with electricity, researchers have been able to make the amphibian's body wriggle as though swimming. If they decrease the intensity of pulsing slightly, the animal suddenly transitions to a walking motion.
Source

The salamander robot's "spinal cord" is just a hardware mimic of the biological salamander's spinal cord.

Central pattern generators
control much of our day to day activity: walking, running, scratching, breathing . . . This activity takes place below the level of consciousness--although we can consciously switch from one pattern to another.

A trained athlete, dancer, or musician will spend years developing central pattern generators with exquisite precision, and superb responsiveness to higher control and feedback. Larry Bird, Magic Johnson, and Michael Jordan did not suddenly wake up one day and discover that they could play basketball. Tiger Woods was not born with his superb control of a golf club. Roger Federer did not become the undisputed best in the world at tennis by being a couch potato.

More intriguing to me are the central pattern generators that are not involved in motor control, but are rather involved in associative cognitive function. These are habits of mind, strange attractors of thought--conscious and subconscious. This is automaticity--the cortical counter-point to spinal pattern generators.

If the pattern generators of the brain and the spinal cord are superbly and intelligently trained over the years, people can accomplish incredible feats.

First of all, these generators have to be prompted at the appropriate times--the critical periods of development. Without the prompting, the child will never develop the motor skills, language skills, mathematical skills, and general cognitive skills that are needed in the modern technological world. That is a waste of human talent which is unfortunately widespread, both in the developed and undeveloped worlds.

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