Of all the robots that end up supporting humans, those that carry out the dirty, dull and dangerous tasks will be the most commercially successful, the president of an American robot maker said Thursday in Tokyo.

"Our goal is to change the world we live in, to solve very important and challenging problems that need to be solved," said Colin Angle, chief executive officer of iRobot Corporation, at the Foreign Correspondents' Club of Japan in Tokyo.

Angle, a robotics expert and cofounder of the Massachusetts-based home and military robot maker, is in Japan to attend CEATEC Japan 2010, a five-day electronics and information technology fair that kicked off Tuesday in Chiba Prefecture.

Angle said Japan is the second-largest market for iRobot's most recognized product, the Roomba, which is programmed to sweep floors.

"Roomba's sales in Japan have been very very strong," Angle said.

The disc-shaped Roomba, created in 2002, is about 34 cm in diameter and about 10 cm thick. It goes about its task by first determining the shape and size of the room to be swept and how dirty it is. It then roves around to suck up any dust and returns to its recharging unit all by itself.

According to iRobot's website, more than 4 million of the robots have been sold in 40 countries. Roomba's distributor said that more than 100,000 units had been sold in Japan alone as of 2009 since its local debut in 2004. The robot is priced between ¥48,800 and ¥79,800.

Angle said the company has seen substantial growth in Japan, although he couldn't confirm local sales figures since iRobot doesn't break down the Japanese market as a segment.

IRobot also produces military robots, including one named the PackBot, which is used to help disable bombs in Iraq and Afghanistan. Angle said some 3,500 of these robots are "saving lives every day."

Angle sees his next great chance coming in the health care market, where Japan's aging population will make it the world's biggest.

"People are getting older. . . We need robots to care for our parents" to extend the period where they can live independently at home, Angle said.