Standard or available as an optional extra on most cars on the market today, cruise control has become a must-have item for anyone making long-distance, high-speed trips. And while cruise control can save your right foot on long-distance trips and keep your car’s speed constant, it isn’t always the most fuel-efficient way to travel, because cruise control will do everything it can to keep your car’s speed constant, even if that means using more energy on long up-hill stretches and slowing down your car on downhill descents.
But now a pair of academics from Germany say they’ve cracked the problem of inefficient cruise control systems with a new set of algorithms capable of acting a little more like a human hypermiler. What’s more, the team say their cruise control algorithm could yield up to a ten per cent improvement in fuel efficiency without any other modifications to the car.
Hypermiling, for those who don’t know, is the name given to those who employ special driving techniques to obtain the best possible fuel economy out of their cars. While many hypermilers are hybrid car drivers eager to obtain unbelievably incredible gas mileage figures out of their already-efficient cars, hardened hypermilers drive many different types of vehicle, sometimes even carrying out aerodynamic DIY modifications to their cars in an attempt to squeeze every last mile out of every drop of fuel.
Naturally, an algorithm can’t add bits to your car to make it more aerodynamic, but as the IEEE explains, professor Hermann Koch-Groeber and graduate student Jue Wang from the University of Heilbronn think they’ve manage to model the driving techniques of hypermilers in such a way that a cruise control system could use it to save fuel.
If you watch a really good hypermiler behind the wheel, they’ll make use of clutch, gears and speed to maximise efficiency. Using their knowledge of the road ahead, they’ll plan further ahead than most drivers, switching into neutral or perhaps even turning off the engine completely to maximise fuel economy on a long downhill straight. Instead of relying on the car’s engine to power it down the hill, hypermilers use the stored potential energy of the car –and gravity — to coast down to the bottom. And while this practice is a legal grey area on non-hybrid vehicles, the results do speak for themselves.
Koch-Groeber says he started his research by learning manual hypermiling techniques, applying what he knew of behind the wheel of a 2012 Ford Focus with manual transmission.
“From my knowledge of the stretch of highway, I knew when it was proper to inaugurate the coasting phase, when I put it in neutral,” he said. Being able to look ahead and predict the road conditions meant that he was even able to start coasting before reaching the crest of a hill, saving as much fuel as possible.
From that point, Koch-Groeber and Wang started to automate the process, using a automated gearbox connected to a computer control system. Unlike a traditional fluid-filled torque-converting automatic gearbox, the automated gearbox used by the duo had the same gear layout and clutch as a manual transmission. Instead of manually disengaging the clutch and changing gears however, a computer does the work instead.
“That’s interesting because to automate coasting I need actuators that shift into neutral and open the clutch, and this has all the actuators already on,” he said. “So I can use bits and bytes to initiate coasting—a huge benefit.”
In an ideal world, the system would work like this: with the destination programmed into the car’s satellite navigation, the car’s cruise control would not only know where the car was going but what the terrain was ahead of the vehicle. Using GPS location data, the car could tell in real-time where it was, and engage and disengage the transmission as required to maximise fuel efficiency, turning down engine idle speed with no load on the engine or even switching it off when not required.
Still in the test phase, Koch-Groeber says he expects to have a prototype system in place by March next year to see if the system would work in the real world. But, he hints, other people in the auto industry — including his former employer, Bosch — are already working on similar technologies for use by mainstream automakers. If you’re interested in the academic study and want to read the duo’s abstract on coasting for passenger cars, you can do so here.
And while the technology is being developed here for traditional gasoline-powered vehicles, there’s no reason a similar technology couldn’t be used by electric cars or future fuel technologies to maximise range.
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