TALLINN - A knee-high, black-and-white buggy rolls down a snowy sidewalk in Estonia's capital and, carefully avoiding pedestrians, stops obediently at the red traffic light of a large intersection.

The six-wheeled robot, on its way to deliver lunch to a client, knows to cross only when the pedestrian light is green, but, armless, it cannot press the traffic light button.

Inventors Starship Technologies have taught their robots to avoid traffic lights with buttons and are now giving them speakers and microphones to help them navigate pedestrian crossings.