Google’s self-driving prototypes are hitting California roads this summer, and they might be trying out a new way of slowing down that sounds familiar to to skiers. When you’re on the slopes, whether you’re slowing down or speeding up depends on which way your skis point. If you point your skis in towards each other, you slow down. But if they’re pointing straight forward, you speed up.
A patent granted to Google Tuesday shows the company applying the same idea to its self-driving cars. The patent, called “steering-based scrub braking,” was first applied for in 2013. The listed inventor is Peter Lombrozo, whose LinkedIn profile says he’s a mechanical engineer at Google.
According to the patent, a self driving car may “turn the pair of wheels of the vehicle in a direction away from parallel to the given direction in which the vehicle is traveling and in the opposite directions to each other so as to reduce the speed of the vehicle.”
As the skiing instructor from South Park put it, to go slowly on skis, you wedge your skis together in the shape of a slice of pizza. To go faster, you make your skis parallel like a pair of french fries. Essentially, Google’s invention describes doing the same thing with a self-driving car's wheels.
Most commercial vehicles use disc brakes to slow down. Using slightly turned wheels to burn off speed turns out to be a much older way of braking a vehicle, called scrub braking. But for lighter vehicles, it’s another way to slow down, and it probably wouldn’t be possible or effective with a human-driven car -- could you calculate the exact wheel angle that would slow you down enough by the time you reach a stop sign at 25 mph?
Google’s invention should be able to make the calculations necessary to slow down by turning the wheels of a vehicle on the fly. According to the published diagrams, both the front and rear sets of wheels can pivot to slow down a car.
This doesn’t mean Google’s prototypes will use scrub braking in the near future. Patents rarely portend products, and the patent says it could be used as a backup system to more traditional brakes. But it’s a great example of just how innovative self-driving cars could be. The possible changes go beyond making self-driving cars more like go-carts -- like Google’s prototype -- or taking out steering wheels or gas pedals.
Once a car is a computer, it’s a great reason to re-examine many of the techniques automakers have used for years. Even something as critical as brakes -- after all, there could end up being a superior way of braking only computers can pull off.