It can take more than fifty years for an idea to jump from toyland to academia, and 10-15 years for an engineering insight to sink in among practitioners, according to a New Scientist story on robotics .
Until recently, robot designers crammed more and more servos and sensors into their robots legs in an attempt to direct joint movement. While this works after a fashion, it turns out that a simple tottering motion is the best way to get robots to walk. In 1938 American inventor John Wilson patented a waddling toy, the Wilson Walkie, that could walk itself down a gentle slope.
In the early 1980s Thomas McMahon at Harvard started working on this insight in his lab. Tad McGeer took up this work, publishing a series of papers in the 1990’s showing that a passive machine, with or without knees, could walk stably downhill with a human-like gait. It has taken 10 to 15 year for the work to sink in. In the last year, three separate teams unveiled two-legged robots that exploit the Wilson Walkie’s principle of motion.
Thomas Kuhn pointed out that "a new scientific truth does not triumph by convincing its opponents and making them see the light, but rather because its opponents eventually die, and a new generation grows up that is familiar with it." The cultural friction on the adoption of new ideas puts an upper limit on the absolute innovation rate as long as humans are in the loop, and would dampen the approach to the innovation singularity.
 Robot special: Walk this way, New Scientist, 04 February 2006 (subscription required for full access)