WEBVTT - How do self-driving cars work?

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<v Speaker 1>Welcome to Brainstuff from how stuff Works dot com where

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<v Speaker 1>smart Happens. Hi. I'm Marshall Brain with today's question, how

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<v Speaker 1>do self driving cars work? Who wouldn't like to have

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<v Speaker 1>a car that drives itself. The idea of being able

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<v Speaker 1>to sleep or to use your laptop during the commute

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<v Speaker 1>to work is certainly appealing. The idea of having your

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<v Speaker 1>car drop you off at the door of a store

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<v Speaker 1>and then go park itself is also attractive. And then

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<v Speaker 1>there's the safety thing. Human beings just are not that

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<v Speaker 1>good when it comes to driving, with millions of automobile

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<v Speaker 1>accidents causing damage, injury, and death every year. If we

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<v Speaker 1>all had self driving cars, it would be great. Two

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<v Speaker 1>recent announcements have made self driving cars seem a lot

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<v Speaker 1>closer to reality. The first comes from the Army, which

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<v Speaker 1>is now using self driving vehicle to guard a large

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<v Speaker 1>military facility and nuclear waste dump in Nevada. And then

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<v Speaker 1>there's Google, which recently announced that it's developed self driving

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<v Speaker 1>cars that have logged over a hundred thousand miles on

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<v Speaker 1>real roads in real traffic. What's going on inside these

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<v Speaker 1>cars to make it possible for them to drive themselves.

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<v Speaker 1>We can take a look at it. By looking at

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<v Speaker 1>Google cars or some of the cars that have participated

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<v Speaker 1>in DARPST Grand Challenge, you could, in theory, turn any

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<v Speaker 1>car into a self driving car. The first thing you

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<v Speaker 1>would have to do is make it possible for a

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<v Speaker 1>computer to control the car. This is not quite as

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<v Speaker 1>easy as it sounds, but it's relatively straightforward. The computer

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<v Speaker 1>needs to be able to turn the steering wheel, push

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<v Speaker 1>the accelerator and brake pedals, move the gear shift control,

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<v Speaker 1>and start the engine. These tasks, at least in experimental

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<v Speaker 1>self driving cars, are often accomplished with electric motors. A

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<v Speaker 1>motor is mounted so it can turn the existing steering

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<v Speaker 1>wheel for example. Another motor is able to put pressure

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<v Speaker 1>on the accelerator and brake pedals and so on. It's

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<v Speaker 1>not a particularly elegant solution, but it gets the job done.

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<v Speaker 1>As production cars become more advanced, drive by wire systems

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<v Speaker 1>are becoming a lot more common, So in a like

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<v Speaker 1>a Prius a Toyota Prius, if you push the brake pedal,

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<v Speaker 1>it might go to a computer and the computer actually

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<v Speaker 1>activates the brakes. There's no direct mechanical linkage between the

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<v Speaker 1>brake pedal and the brake mechanism that's called drive by

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<v Speaker 1>wire when the computer is sitting there in the middle.

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<v Speaker 1>In cars with drive by wire, a computer can hook

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<v Speaker 1>directly into that existing control system without having to have

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<v Speaker 1>these motors hanging out in the driver's area. The next

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<v Speaker 1>thing that a self driving car needs is sensors, and

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<v Speaker 1>here things get pretty complicated. Today, a human being drives

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<v Speaker 1>his car by using his or her eye is as

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<v Speaker 1>the soul sensor. The human visual system is amazing in

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<v Speaker 1>this regard because it's able to accurately judge the presence

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<v Speaker 1>of obstacles, their distances, their relative size based on distance,

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<v Speaker 1>their speed, and so on. A human being also recognizes

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<v Speaker 1>what he or she is seeing, So if a human

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<v Speaker 1>being sees a fence, you can accurately predict with high

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<v Speaker 1>certainty that that fence is not going to jump out

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<v Speaker 1>into the middle of the road and do something to you.

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<v Speaker 1>On the other hand, if there's a child playing with

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<v Speaker 1>a ball on a sidewalk, it's a completely different story,

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<v Speaker 1>and humans can recognize that instantly. Computer vision systems are

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<v Speaker 1>nowhere near this point in their development, so they rely

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<v Speaker 1>on extra sensors to provide more information. Self driving cars

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<v Speaker 1>do have camera based vision systems, and they use it

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<v Speaker 1>to see other cars, unexpected obstacles, road marking signs, and

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<v Speaker 1>so on. But in addition, self driving cars almost always

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<v Speaker 1>have GPS sense, or so they have a better idea

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<v Speaker 1>of exactly where they are and where they're pointing. They

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<v Speaker 1>also have light our systems laser scanners that can look

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<v Speaker 1>for nearby objects and accurately judge their distance. They also

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<v Speaker 1>have radar systems normally, and they may have infrared sensors

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<v Speaker 1>to improve night vision. These sensors all feed into a

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<v Speaker 1>powerful onboard computer, often multiple computers that are usually located

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<v Speaker 1>back in the back catch area of the trunk. They

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<v Speaker 1>could fill an entire trunk in fact, and these process

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<v Speaker 1>all the data that the sensors are gathering. The internal

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<v Speaker 1>computer will have access to a database of maps and

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<v Speaker 1>other relevant information as well. For example, engineers may pre

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<v Speaker 1>drive or route and pre catalog all the signs, road markings, curves, crosswalks,

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<v Speaker 1>traffic lights, and so on that the self driving car

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<v Speaker 1>will encounter along the road. This way, the car knows

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<v Speaker 1>what to expect and complan accordingly. Finally, the onboard computer

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<v Speaker 1>may also be communicating by radio, with bigger computers holding

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<v Speaker 1>even more data in nearby buildings. You might wonder why

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<v Speaker 1>the driving task, which seems effortless to just about any

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<v Speaker 1>normal human adult, would be so hard for a computer.

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<v Speaker 1>It's because the human brain is deceptive. Although it's small

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<v Speaker 1>and silent compared to a desktop computer, the human brain

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<v Speaker 1>still has more power than mankind's biggest fills a whole

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<v Speaker 1>building supercomputers. The massive amount of computing power in the

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<v Speaker 1>human brain is what makes driving appear to be so

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<v Speaker 1>easy for us. In thirty or forty years, our computers

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<v Speaker 1>will have that same kind of power in a small

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<v Speaker 1>package if things keep progressing at their current rate. Be

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