'Minesweeping' robot keeps carpets clean

The Roomba robotic vacuum cleaner has a new mission: to seek and destroy.

IRobot came out with a new line of robotic vacuum cleaners on Monday that, according to the company, feature longer battery life, overall improved performance and an ability to detect dirt.

When the robot drives across a particularly dirty patch of carpet or floor, sensors begin to "listen" to dirt through a vibration detector. The navigation system then steers the robot in circles in the area to eradicate all of the vibration anomalies, at which point the robot resumes its normal course.

Although robotics has not lived up to some of the hype and promise of the last two decades, the market has begun to develop, thanks to improved technology and a change of thinking on how and where robots will be most useful.

Most companies now are no longer trying to develop humanoid companions. Instead, they are developing mobile units that can go into dangerous areas -- such as sewer pipes or nuclear power plants -- or that can perform repetitive, often menial tasks.

IRobot, which spun out of the Massachusetts Institute of Technology, develops robots for both types of applications. The company has created a number of reconnaissance robots for the military, including the PackBot, a robotic minesweeper being used in Afghanistan.

On the other end of the spectrum, the Roomba cleans up the living room and, in all likelihood, could not be used by a mad scientist to take over the Earth. Still, the products share a common heritage. The navigation algorithms and the sensor technology that allow the Roomba to avoid falling down stairs or running into obstacles come from the company's government work, according to a spokeswoman.

"It is a minesweeper for dirt," she said.

The first model of the Roomba, which carries a price tag of $199 (about £106), has sold more than 500,000 units, according to the company.

The new Roomba Discovery sells for $249 and comes equipped with the Dirt Detect technology, a home base that it scurries to for recharging, and a bag that holds three times as much dirt as bags for previous models. The new battery charges in three hours and can last two hours, and design modifications allow the new Roomba to shift more easily from hardwood to carpet.

A scaled-down version called Roomba Red sells for $149.

The vacuums are now available on the iRobot Web site and will be available through other US retailers later in the year.