Four of Japan's leading robot startups have joined forces, brought together by a common concern that neighboring South Korea could pull ahead in the race to transform robots from science fiction fantasy to commercial success.

Japan, which has long led the world in robo-technology, has created machines that can clean, dance, greet, feed, monitor, relax and befriend. But for all the buzz, so-called intelligent service robots have been slow to penetrate the average home, which is still more likely to shell out money for the latest flat-screen television than a pricey humanoid.

The companies — Tokyo's ZMP Inc., Nagoya's Business Design Laboratory Co., Osaka's Vstone Co. and Fukuoka's Tmsuk — said Wednesday that new South Korean robot legislation passed earlier this year compelled them to form the Association For Market Creation Of The Future Generation Robots to cooperate in research, development and marketing.