Visionaries have been imagining driverless robotic cars for decades, but one big, difficult question was how they would navigate the roads safely. Google's program to develop driverless cars, which began to shift into high gear in 2014, depends upon a synergy of GPS, sensors and cameras to accomplish that feat.
The GPS device plots the car's location, speed and direction relative to the destination, while a laser on the roof helps create a digital 3-D model of nearby objects to tag possible hazards. Cameras scan traffic lights, road signs and other visual markers. The technology has one significant limitation — it's only safe to use on roads that Google has mapped digitally in careful detail. And the cars can go no faster than 25 mph (40 kph) to ensure they're scanning that information [source: Sun].