Will lidar really reduce accidents?

It’s a vital element of tomorrow’s self-driving cars, but key questions remain about lidar’s ability to do what older tech can’t.

Assistance systems such as Tesla’s Autopilot focus on moving cars, not parked ire engines

IT DOESN’T TAKE A GENIUS to spot a parked fire engine in the road ahead of you. So you might expect a car packing a state-of-the-art driver assistance system to do just that. Yet a Tesla Model S recently had a high-profile prang on a dry, bright morning in Los Angeles. The car is fitted with Autopilot – so even if the driver is distracted, the car should be able to avoid the collision or reduce its severity.

The driver reportedly told fire officers at the scene that the car was in Autopilot mode. Autopilot does not drive the car, despite what the name might suggest; rather, it’s designed to assist the driver. As a Tesla spokesperson told us: ‘Autopilot is intended for use only with a fully attentive driver.’

Its features include lane keeping and adaptive cruise control. It could have applied automatic emergency braking, but wouldn’t have automatically steered the car around the fire engine, which was attending the scene of an earlier accident.

Whatever actually happened in this case, it highlights the limitations of current tech.

Assistance systems such as Autopilot are programmed to disregard stationary vehicles in most situations. The focus is on keeping a safe distance from moving vehicles, without slamming the brakes on every time the system catches sight of a parked car.

Radar transmits radio waves and interprets the reflection back from an object. While it can detect large objects, and easily calculate speed and distance in all weather and light conditions, it can’t distinguish colours or tell the difference between large and small objects. A radar image of a street would be a mass of objects from cars to lamp posts, cyclists to litter bins. It’s down to the software engineers to programme the system so that it ignores the insignificant ones. There’s clearly room for error here.

So if radar isn’t enough, what about the system that’s being talked of as the next step up from radar, ‘light detection and ranging’, or lidar? It uses pulsed laser beams to build up a 3D digital representation of the area. It can detect specific objects and calculate the distance to them as well as ‘seeing’ the edge of the road or white lines. It can, however, be affected by rain, snow and fog. At the moment it’s expensive and bulky – you’ll have seen pictures of development prototypes equipped with lidar hardware that looks like a traffic cone attached to the roof. Those cones house lasers rotating 360° to knit together an image of its surroundings. That costs about £50,000 per car.

The next generation of lidar, soon to be seen in semi-autonomous vehicles, replaces those cones with solid state hardware the size of a paperback book, using a tiny microelectromechanical system to transmit the laser pulse.

But lidar is by no means perfect. It doesn’t like fog. Some experts warn of potential eyesight damage. Others believe lidar is susceptible to ‘seeing’ non-existent ‘ghost’ cars when close to other lidar-kitted vehicles. It will never be known if a lidar-equipped car would have avoided that fire truck, but what we can be certain of is that the path to fully autonomous driving will be strewn with challenges that need to be overcome before it is a reality for everyday transport.