For the first time in my life, I own a car that has Cruise Control. I've rented many such cars, and I was really looking forward to it. “CC” is still the best way to make sure that you don't drive twenty miles over the speed limit unintentionally, and it's very restful. But that's not important now.
We bought a car that would get good gas mileage. And it does. But not on Cruise Control. CC keeps your car going at a constant speed, more or less. It uses a lot of gas to go uphill, and it rarely coasts enough to lose speed while minimizing gasoline use. We need the other kind of Cruise Control.
I want to tell my car to try to drive at a given speed. And then I want it to cruise such that it uses as little gas as possible, while trying to keep near that speed. I know that in principle, a car computer can do this better than I can. But I wonder what a car would have to know, to do this other kind of Cruise Control.
The interesting question is whether a car's computer would need a camera and a topological map of the US to cruise and conserve fuel. Because when I drive to conserve fuel, I consider whether I'm going uphill or down, what cars are in front of me, and where the next light is. Could a car computer conserve better without knowing what I know?
I'll give you a good example to illustrate the complexity of fuel conserving. Near my home, I often get on a 45 mph road that goes uphill for awhile, then downhill for a long while. When I turn onto this highway, I want to accelerate to 45 mph as fast as possible (well, fast, anyway) to get into the gear that uses the least gas. But suppose I accelerate, and then a car turns slowly onto the road ahead of me? Then I'll have to slow down, and I will have wasted the gas I used to accelerate. (I can look ahead to see if a car is going to turn onto the road; my car's computer would need a camera to do the same. Or maybe my car would have to tune into a "mesh" network to find out what nearby cars were doing.) Similarly, you don't want to accelerate uphill if the traffic light ahead of you is going to make you stop right away. In fact, here's how a traffic light gives you a really hard decision: If you coast to the light (saving gas) but it turns red on you, then you know that you could have saved gas by speeding to pass the light before it turned red. A car's computer, tuned in to a wireless network that reports on the status of nearby traffic lights, could handle this decision better than I do now.
Let's call this other thing “Fuel Cruise Control.” Or can you suggest a better term? I want Fuel Cruise Control!
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3 comments:
Might a sensor that noted changes in level be as good and simpler than a topo map?
Likewise if vehicles were equipped (and retrofitted) with a transponder type devise which narrowcast position and speed to a 1000ft radius, or so, combined with a traffic control net which monitored and advised traffic, every thing would be perfect ...
Until we run into the twenty-leben things I haven't taken into account.
Maybe light rail and gyro-copters would be better. And Cheaper.
--ml
I was also thinking about a sensor to tell whether the car is going up or down. That would not be as good as knowing the topology, because I look WAY ahead (not a little ahead) to decide what to do. You can maintain speed on long gentle upgrades while using little gas. A faster upgrade requires slowing down or accelerating, depending on how long the hill will be.
In any case, a camera (or in 20 years, a wireless network) is needed to sense the presence of other cars going slow in front.
-PB
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