A dog-shaped robot that uses sensors and preprogrammed software to mimic the gestures and habits of real dogs went on sale on June 1. Named Aibo, the four-legged robot developed by Sony Corp. has proven to be a big hit, selling out just 20 minutes after the manufacturer began accepting orders over the Internet.

In Japan, 3,000 units were put on sale exclusively over the Internet for 250,000 yen each, and another 2,000 were made available in the United States, where they carried a 2,500-dollar price tag.

By using the latest artificial-intelligence technology, Aibo can learn from experience and even express "emotions" like anger and joy. If it's shown a red ball and then hit on the head, it will step back and shake its head when it sees the red ball again. But if it is patted gently the first time it sees the ball, it will wag its tail the next time and start chasing the ball around.

The robot measures 27 centimeters (10 2/3 inches) long, weighs 1.7 kilograms (3 pounds 9 ounces), and is powered by batteries. It can be made to sit, lie down, and roll over by remote control; owners can even have it to come to the door when they return from work.

The name Aibo stands for "artificial intelligence robot"; it's also the Japanese word for "pal."

Although the robotic pet sold out quickly, Sony says it has no plans to market additional units right now.

Photo: Could there be robotic pet in your future? (Sony Corp)