How Driverless Cars Will Work

Image Gallery: Concept Cars The marketing manager of Team-LUX exhibits a driverless car at the Science Museum in London. See more concept car pictures.
Chris Young/AFP/Getty Images

We've all had those days: rushing around, trying to get errands done. You finally picked up the dry cleaning, and now you've got to get to the post office before it closes. So you go, pedal to the metal, thinking about what you need to get at the grocery store for dinner, when it hits you -- or, you hit it. While your mind was someplace else, the car in front of you stopped, and you rear-ended it.

What could have prevented the accident? The obvious answer is that you could have -- by paying attention. But that answer isn't so simple. Driver error is the most common cause of traffic accidents, and with cell phones, in-car entertainment systems, more traffic and more complicated road systems, it isn't likely to go away. But if drivers aren't going to concentrate on the road, who is? If technology continues on its current course, your car will do the concentrating for you. Automakers are developing complex systems that allow cars to drive themselves. They're also furthering existing technologies such as self-parking and pre-safe systems. You may even be surprised to find out your old clunker already sports some driverless technologies.


In this article, we'll learn about the technology behind cars that can operate with minimal input from drivers, including how far away these cars are from production and some of the legal issues around letting the robots take over.

Dawn of the Driverless Car

Anti-lock brakes, a standard feature in most cars, are a basic form of driverless technology.
2008 HowStuffWorks

You can't just jump head-first into driverless cars. That's a recipe for driverless disaster, my friend. One of the earliest driverless cars was Stephen King's "Christine," remember, so let's all be grateful that idea didn't make it to market before the quirks had been worked out.

An early -- and non-murderous -- first step toward driverless cars came in the 1980s, and it's still with us today: anti-lock brakes (ABS, according to that terrifying light on the dashboard). Technically, anti-lock brakes do need the driver to step on the brake pedal in order to work, but they perform a function that drivers used to have to do themselves. When a car is braking hard and doesn't have anti-lock brakes, the wheels can lock up, sending the car into an out-of-control skid. In a car without anti-lock brakes, the driver has to pump the brake pedal to keep the wheels from locking up. With anti-lock brakes, the system does the pumping for you -- and it does it better and much faster than you ever could, thanks to speed sensors in the wheels.


About ten years later, manufacturers used those same sensors to take the next step toward driverless cars: traction and stability control. These systems are a step up the sophistication ladder from ABS. They use the sensors at the wheels to detect when a car might go into an out-of-control skid or roll over, and then they use ABS and engine management to keep the car on the road and the shiny side up. Unlike a driver, these systems can apply the brakes and increase or decrease power to individual wheels, which is often better than brakes or power being applied to all four wheels by a human foot mashing the brake pedal in a blind panic. See? Already your car is a better driver than you, and we're only at, like, 1995.

The future is now!

Cruise control is a basic driverless system. Adaptive cruise control falls closer to the sci-fi end of the spectrum.
Ye Liew/

­So, we moved from "Christine," a driverless car that actively wanted to kill you, to the cars of the 1980s and 1990s that want to keep you safe. In the 21st century, where science fiction is everyday life, pre-safe systems are more common, and not just in quarter-million-dollar cars upholstered in rich Corinthian leather. This technology is available even in everyday family cars; the kind upholstered in whatever best hides sippy-cup slip-ups. The systems differ depending on the car, but what all have in common is that they can anticipate crashes and prepare the car to keep the occupants safe.

Say you come around a corner only to find a garbage truck stopped in your lane. In a car with a pre-safe system, an alarm might go off as you near the truck's odoriferous maw. While you yell the swear words of your choice but still do nothing useful, the pre-safe system might start priming the brakes so that just touching the pedal will apply their full force -- if you ever find the presence of mind to stomp the brake pedal, that is. While all that's going on, the car will reduce engine power, which will slow the car and reduce the severity of the crash, if there is one to come. At this point, some of the high-end systems are able to stop the car completely, all by themselves, usually under a certain speed. Finally, if the system detects that a crash can't be avoided, it'll prepare the airbags for deployment and tighten all of the seat belts. What's really amazing is that it will do all that in less time than it takes the driver to simply slam on the brakes. It's only a matter of time before the car sighs and expresses its disappointment with your driving ineptitude.


You know what else makes our cars sad for the puny humans who drive them? Our terrible parking abilities, especially parallel parking. Several manufacturers offer automatic parking systems on everything from SUVs to compact cars and hybrids. The systems use sensors all around the car to guide it into a parallel parking space -- no human input required. Before it can work, the driver has to find a parking space, position the car next to it, and use the navigation screen to tell the car where it should go. Still, the self-parking system is a big achievement in driverless car technology. With it, the car behaves like a driver might -- reading the area around it, reacting accordingly and going safely from point A to point B. While it's not the same as sitting back and relaxing while your car drives you home for the night, it's the first step in that direction.

Cars of Tomorrow. Still not Flying.

HSW 2008

Fine, nerds. We get it. We thought we'd have flying cars, but we don't. You know what we do have? A bunch of cars driving around the greater San Francisco metro area with bizarro contraptions on the roof! That's equally awesome, right?

Maybe it's a little more Batman DIY rather than Superman with powers at birth. But it works. Google has had a fleet of driverless cars since 2009, and they've driven over a half a million miles (804,672 kilometers) without a crash. Human drivers get in an accident about every half a million miles (804,672 kilometers) on average in the United States, so either the Google cars are due, or they're going to out-drive humans yet again.


Several manufacturers have driverless cars in the works, but since Google of all places has the jump on this project, they're also more forthcoming (sort of) about how their cars work. The Chauffeur system, as they call it, uses lidar, which stands for light detection and ranging and is not related to the liger, which is a lion and a tiger. Lidar works like radar and sonar, but it's far more accurate. It maps points in space using 64 rotating laser beams taking more than a million measurements per second to form a 3D model in its computer brain that's accurate to the centimeter. Preloaded maps tell the system where the stationary stuff is -- traffic lights, crosswalks, telephone poles -- and the lidar fills in the landscape with moving objects like people. It also has regular ol' radar, a camera and GPS to help out.

But don't snap that sleep mask over your eyes and lean the driver's seat all the way back just yet, though. Chauffer still needs you to take over sometimes, like pulling out of or into your garage and driveway or negotiating tricky highway interchanges. Not even a robot car can understand left-lane exits.

Google's system isn't necessarily married to the Prius, though those have been the cars used most often during testing so far. That big bracket could be bolted onto any car with the sensors and software to handle it -- and the money. Chauffer's price will have to come down from the $75,000 neighborhood to be adopted by most drivers. Google expects to have it ready and -- fingers crossed -- cheap enough for people to afford by 2018.


Are they legal? Are they even OK?

HSW 2008

Semiautonomous cars, in the lingo of the day, are legal for testing only -- not for private owners -- in four places so far: California, Nevada and Florida, plus the District of Columbia. (Nevada added an infinity sign to the license plates of semiautonomous cars.) The National Highway Traffic Safety Administration (NHTSA) released some suggested guidelines, which is as non-legally binding as it sounds.

Not only will new laws have to be drawn up, but our old laws will need some serious rewording, too, since people in the dark ages of driverless cars (any year before this one, really) assumed there would be a driver with his or her hands on the wheel and feet on the pedal -- and not just for show. New York law says straight-up that you have to have a hand on the steering wheel while the vehicle is in motion. Chauffer and its semiautonomous friends do not have hands.


There's even a Geneva Convention on Road Traffic, which the U.S. Congress ratified in 1950. This is when cars had fins, not rotating lasers and lidar. People back then did not anticipate a car that could drive itself. Yet they did anticipate those flying cars. They were wrong about a lot of things. Anyway, according to this Geneva Convention, the driver of any vehicle, whether it's a car or a horse-drawn cart, has to have control. And they do assume the driver is a person, not K.I.T.T. The European Union takes this quite seriously -- as of now, a human driver must be in control of a vehicle at all times. No robots allowed.

As the technology progresses, the legal issues will follow. If your semiautonomous car's laser array skips over a pedestrian while you snooze and your car hits him, are you at fault? Is Google at fault? Is the lidar manufacturer? Is the pedestrian? Because he really should have been staring at your car, in awe of its futuristic capabilities and well-aware of its location -- at least enough to not find himself underneath it. Only time will tell. But it probably won't be the pedestrian's fault he wasn't sufficiently amazed by your car.


Driverless Cars to Come

Urban Light Transport is a revolutionary driverless taxicab. It's yet to be seen whether the masses will place trust in driverless cars.
ATS Ltd/BWP Media/Getty Images

Google is not the only game in town when it comes to semi-autonomous cars. There are several in the pipeline for the next decade or so:

  • The 2014 BMW X5 with the Traffic Jam system can already mostly drive itself up to 25 miles per hour (40.2 kilometers per hour), though the driver still needs to keep a guiding hand on the wheel.
  • Tesla says it will have a car that operates on autopilot 90 percent of the time, which is similar to Google's Chauffeur, by 2016 -- if these two systems are legal by then, that is.
  • Mercedes-Benz brought its self-driving S500 Intelligent Drive car to the Frankfurt Auto Show in 2013, promising to have a version on the market in 2020.
  • An Audi A6 Avant at the 2013 International Consumer Electronics Show used the Mobileye system to drive itself at speeds up to 37 miles per hour (59.6 kilometers per hour). It should reach showrooms by 2020.
  • Nissan has outfitted an all-electric LEAF with an array of lasers and sensors so it can drive itself. The head of Nissan, Carlos Ghosn, predicts it will be the first semiautonomous car to market -- in 2020.


Lots More Information

Author's Note: How Driverless Cars Will Work

This is the kind of article that feels like the information and technology are moving faster than my fingers can type. Even though I'm on top of automotive technology -- or I fancy myself to be, anyway -- I was surprised to learn that a BMW available about five minutes from now already drives itself at low speeds. Granted, it can't fly solo, but it's close. The fact that the competition is so seemingly fierce already made me wonder why we care about self-driving cars. I came to the conclusion that it's not because we're too lazy to drive the things ourselves; it's because we're too busy. There are a million things we'd rather be doing than driving a car, like watching a movie. Or taking pictures of the landscape as we pass. Or sleeping. Or calling our moms. Driving isn't the key to freedom that it used to be. Bandwidth is.

Related Articles

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