These stair lights use laser beams to detect when the stairs are entered and automatically softly ramp on the lights. The lights then turn off one by one in the direction that the person (or animal) was walking. There is a
video on the site that will give you a better idea of the full operation.
http://www.alan-parekh.com/stair_lights.htmlhttp://www.alan-parekh.com/index.htmlThis prototype was also turned into a kit if anyone is interested.
http://alan-parekh.vstore.ca/index.php/cPath/1_2