ALEX DAVIES | TRANSPORTATION | 02. 06.18 | 06: 08 PM

WHAT IS , WHY DO SELF-DRIVING CARS NEED IT, AND CAN IT SEE NERF BULLETS?

IF YOU'VE BEEN in , Pittsburgh, Boston, San Francisco, or any of the other cities where autonomous cars are crawling the streets in a 21st century version of drivers ed, maybe you've wondered: What's up with that overgrown gumdrop-looking spinning thing on the roof? That, dear carbon-based life form, is lidar, perhaps the most important piece of hardware in the race to unlock self-driving cars for everybody.

Lidar works much like radar, but instead of sending out radio waves it emits pulses of infrared light—aka lasers invisible to the human eye—and measures how long they take to come back after hitting nearby objects. It does this millions of times a second, then compiles the results into a so-called point cloud, which works like a 3-D map of the world in real time—a map so detailed it can be used not just to spot objects but to identify them. Once it can identify objects, the car's computer can predict how they will behave, and thus how it should drive.

Self-driving cars use other sensors to see, notably radars and cameras, but laser vision is hard to match. Radars are reliable, but don't offer the resolution needed to pick out things like arms and legs. Cameras deliver the detail, but require machine-learning-powered software that can translate 2-D images into 3-D understanding. Lidar, by contrast, offers hard, computer-friendly data in the form of exact measurements.

That's why every serious player in the self-driving car race believes the laser sensor is an indispensable ingredient for a fully robot car, the kind that doesn't need a steering wheel or a human hand. (The notable exception is Tesla's Elon Musk, who insists cameras can do the job.) This is why lidar is at the center of the blockbuster legal case between and Uber: The company that started life as 's self-driving car project says that when its longtime engineer Anthony Levandowski left for Uber, he brought Waymo's lidar trade secrets with him.

It's also why dozens of companies are competing to overcome lidar's key weakness: It's too young for a rough life on the road.

This laser sensing technique has been around for decades—NASA's Apollo 15 used it to map the moon—but it wasn't until 2005 that it came to the world of cars. That's when an engineer named Dave Hall, CEO of a speaker manufacturer called Velodyne and a participant in Darpa's Grand Challenge self-driving vehicle race, decided he needed a better way for his Toyota Tundra to see its surroundings. He built 64 laser emitters into a device that resembled a flattened disco ball, stuck it on the pickup's roof, and all of a sudden had a new kind of vision. Other teams that had been using primitive laser scanners gushed over the development. So Velodyne stopped making high-end speakers and started making . When the teams came back for another race in 2007, every serious contender had a Velodyne lidar on its roof.

More than a decade later, autonomous driving is on the verge of commercialization, but lidar remains relatively underdeveloped. First, it's expensive. The cheapest sensor on the market is the $4,000 Velodyne puck, but any city-dwelling robocar would need several to see all its surroundings. That's a lot of money to add to the cost of every car. (Big players like Waymo and General Motors have in-house versions of lidar, and they don't reveal what they cost.) Second, making it work on a car is really hard. Anything going into vehicles has to be robust and reliable, able to withstand a life of potholes and temperature extremes, and it has to keep working for years. Deploying AVs in fleets run by a single operator will ease those problems (you can amortize cost by running the vehicles nonstop and bringing them in for regular maintenance), but still: Lidar needs to get better.

For a look inside this all-important laser sensor, we met up with Austin Russell, the CEO of Luminar, the lidar company he founded six years ago, after dropping out of Stanford at 17. (Slacker.) Russell, who has already signed a deal to work with Toyota, says his sensor can see much farther and with better resolution than anything on the market now. But can it see the dart from a Nerf gun? Watch the video above to find out. (https://www.wired.com/video/watch/all- about-lidar-the-laser-shooting-wonder-box-that-could-make-self-driving-cars-real/)

Link to original article: https://www.wired.com/story/lidar-self-driving-cars-luminar-video/