Willow Garage is out to transform the world of robotics with a formula that has helped make stars of Apple gadgets and Facebook.

The Northern California company believes that third-party applications can do for robots what they did for the iPhone and the world's top online social networking service.

An open-source ross.org software platform along with a PR2 robot priced at 400,000 dollars combine in a technology mix that lets software savants craft applications to make machines do their bidding.

Willow Garage began selling the robots late Tuesday in what it depicted as a step on the journey to the kinds of personal, affordable robots science fiction writers have long envisioned.

"This is fundamentally going to change the pace of development," Willow Garage co-director Keenan Wyrobek told AFP.

"It will be a couple of years before robots get priced down to being in the house, but this is an absolutely necessary step to get there."

University of California, Berkeley, researchers that took part in a test phase got a PR2 to fold towels and match pairs of socks from the laundry.

Engineers at German technology giant Bosch had one of the robots sorting and delivering mail to desks in an office.

Students at the University of Pennsylvania had a PR2 "reading" music and playing songs by rock bands U2 and the Beatles using drums and an electric organ.

Video of robots in action was posted online at willowgarage.com/blog.

The PR2 is intended to spare researchers from wasting time, effort and resources on building their own robots from scratch.

"Most of the people who want PR2 are software gurus; crazy good software developers that have some cool app in mind," Wyrobek said.

"We are opening the field to software developers like what happened in the smartphone space, or Facebook and all those social networks."

PR2 moves about on wheels and has arms with changeable grips. It stands four feet 1.2 meters) tall but has a telescoping spine that lets it rise to 5.5 feet (1.6 meters). The machine also has an array of sensors.

"If you have some cool idea you want to develop, it gives you a good starting point," Wyrobek said.

The robots are assembled in Menlo Park, the California city where Willow Garage was founded in 2006.

Proven leaders in the open-source software community can qualify for a reduced price of 280,000 dollars for a robot, according to Willow Garage.