The Electrification of Self-Driving Cars

The Detroit Free Press has a long article on why self-driving cars will be mostly electric, instead of gas powered.

“There are a lot fewer moving pieces in an electric vehicle. There are three main components — the battery, the inverter and the electric motor,” said Levi Tillemann-Dick, managing partner at Valence Strategic in Washington, D.C., and author of “The Great Race: The Global Quest for the Car of the Future.”An internal combustion engine contains 2,000 tiny pieces that have to be kept lubricated and they break every once in a while.”

That’s probably true (although I’m not a powertrain expert), and it might account for why big OEMs are going electric vs. gas for their self-driving car fleets.

But there’s a more pressing and practical reason for self-driving car engineers working on today’s vehicles: it’s not possible to make most purely gas-powered vehicles self-driving.

It all comes down to braking. Hitting the brakes is still a purely mechanical function in almost all cars, for safety reasons. The logic is that computers are less reliable than mechanical parts, and you don’t want anything to jeopardize the functioning of the brakes.

However, that means that it’s not possible to retrofit the car drive itself, because there’s no computerized way to tell the car to brake.

The solution is to use electric and hybrid vehicles, which have electronic brake controls build into the hybrid powertrain. Combine that with some sort of brake control from parking assistance, and that’s enough to control to make a self-driving car stop.

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