LEAF needs new cruise control algorithm - Like Volvo trucks

I think that most of us don't use the LEAF's cruise control because if you are traveling over any kind of hills, you can do better by dropping speed on the climb and picking up speed on the descent. As we all know (or should know) it's better to not have used energy from the battery, than to have to put some back. The round-trip efficiency in/out of the battery is much debated here on the MNL forum, but realistically is probably no better than 50%.

Volvo trucks now have an intelligent cruise control system, called "I-See" that does not try to hold one speed. It operates like we do, speeding up on the downhill and slowing down on the uphill. This system is touted as improving fuel efficiency by 5% without recovering any of the vehicles kinetic energy.

Here's a link to an article on the system: http://www.nelsonpub.com/cms/dfx/opens/article-view-dfx.php?nid=4&bid=162&et=featurearticle&pn=04.

JohnOver said:

Volvo trucks now have an intelligent cruise control system, called "I-See" that does not try to hold one speed. It operates like we do, speeding up on the downhill and slowing down on the uphill. This system is touted as improving fuel efficiency by 5% without recovering any of the vehicles kinetic energy.

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Douglas Aircraft had something like that on planes delivered to Alaska Airlines. It would allow the plane to go up and down 250 feet with the wind currents, as opposed to constantly working the auto-throttles to stay perfectly level and on speed.

Cruise control could set a fixed power level rather than a fixed speed. This would work as you described, but if I were implementing it I would go a step further and put a maximum and minimum speed as well. So say you set it to 12kW and that keeps you at 58mph on level ground. I'd put in 65mph max and 50mph minimum so that if you fell to the minimum it would apply more power to maintain a minimum speed and then if you were going downhill faster than maximum it would reduce power to not exceed the max.

I use cruise control all the time when driving the Freeways, to hold a constant speed. Changing speeds up & down hills on the freeway would be BIG trouble, and would produce many "bird" salutes around here. :roll:

JohnOver said:

I think that most of us don't use the LEAF's cruise control because if you are traveling over any kind of hills, you can do better by dropping speed on the climb and picking up speed on the descent.

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Speak for yourself! I use cruise control EVERY time I'm on the highway and think it works fine as designed. As long as you keep a reasonable speed (I keep it under 60), it seems to be very efficient as well.

Stanton said:

JohnOver said:

I think that most of us don't use the LEAF's cruise control because if you are traveling over any kind of hills, you can do better by dropping speed on the climb and picking up speed on the descent.

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Speak for yourself! I use cruise control EVERY time I'm on the highway and think it works fine as designed. As long as you keep a reasonable speed (I keep it under 60), it seems to be very efficient as well.

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Guys, he's not suggesting that the cruise control doesn't work fine. What he is doing is exploring an automated way to increase efficiency up and down hills. It doesn't have to have a wide speed delta; it might only be 5 or 10 miles an hour.

TonyWilliams said:

JohnOver said:

Volvo trucks now have an intelligent cruise control system, called "I-See" that does not try to hold one speed. It operates like we do, speeding up on the downhill and slowing down on the uphill. This system is touted as improving fuel efficiency by 5% without recovering any of the vehicles kinetic energy.

Click to expand...

Douglas Aircraft had something like that on planes delivered to Alaska Airlines. It would allow the plane to go up and down 250 feet with the wind currents, as opposed to constantly working the auto-throttles to stay perfectly level and on speed.

Click to expand...

Airbus does that, too. It has a buffer of altitude and airspeed before it adjusts the throttles in cruise. Our car should be able to keep up with a 24 year old airplane.

derkraut said:

I use cruise control all the time when driving the Freeways, to hold a constant speed. Changing speeds up & down hills on the freeway would be BIG trouble, and would produce many "bird" salutes around here. :roll:

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+1

Yes Sir. Gotta love those big trucks crawling up hills and zooming down the other side.

JohnOver said:

I think that most of us don't use the LEAF's cruise control because if you are traveling over any kind of hills, you can do better by dropping speed on the climb and picking up speed on the descent. As we all know (or should know) it's better to not have used energy from the battery, than to have to put some back. The round-trip efficiency in/out of the battery is much debated here on the MNL forum, but realistically is probably no better than 50%.

Volvo trucks now have an intelligent cruise control system, called "I-See" that does not try to hold one speed. It operates like we do, speeding up on the downhill and slowing down on the uphill. This system is touted as improving fuel efficiency by 5% without recovering any of the vehicles kinetic energy.

Click to expand...

Thanks, but no thanks. I use the cruise control all the time (probably >80% of miles driven are with CC on) and it works perfectly the way it is with one exception: It doesn't use the full regen available so I have to ride the brake pedal on steep downhills to get enough regen. This of course cancels CC completely. So please make the full regen available to CC regardless of driving mode.

Slowing down and speeding up defeats the purpose of CC, drive manually if you want to do that. Just don't do it with cars behind you please, few things are more annoying than people who slow down uphill and in turns and then speed up again when you have an opportunity to pass them...

If you want to save energy, just keep a (steady) lower speed where you can without hindering anyone. 10 mph slower makes a HUGE difference.

+1 I use cruise most-all the time. The argument could also be made that free-wheeling down a hill at 70 is no more efficient than regen at 60 due to increased drag...

derkraut said:

I use cruise control all the time when driving the Freeways, to hold a constant speed. Changing speeds up & down hills on the freeway would be BIG trouble, and would produce many "bird" salutes around here. :roll:

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I agree that if ECO mode is chosen the speed should be allowed to drift up and down 3 to 5 mph.
Or held near constant in the Drive mode as it is now.

smkettner said:

I agree that if ECO mode is chosen the speed should be allowed to drift up and down 3 to 5 mph.
Or held near constant in the Drive mode as it is now.

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I got to experience the LEAF chasing it's set speed over rolling hills coming back from Davis. Had to go manual before others driving around me and I went nuts as I constantly jumped ahead and fell behind the same traffic over and over. Definitely distracting as well as inefficient.
When I got the Fit EV, I first thought the Cruise Control was broken, as it would turn on, but not engage. Turns out it doesn’t work in “B gear" for the reasons mentioned. But in “D” and in ECON mode, it does just what you’re asking. Speed will vary as much as 5 mph in rolling terrain and the cruise won't chase it over a nominal (economic) power setting. Not perfect, but much more usable in rolling terrain. Normal and Sport mode hold set speed more closely as they use progressively higher power levels (and regen) to maintain speed.

smkettner said:

I agree that if ECO mode is chosen the speed should be allowed to drift up and down 3 to 5 mph.
Or held near constant in the Drive mode as it is now.

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Again, no thanks. I always drive in ECO since I do not like the "nervous" accelerator pedal mapping in "D"-mode. If the speed were to drift in ECO I would be forced to use D when using CC. Then CC would have even less regen to use, redering it useless also in moderately steep downhills.

Why is it difficult for the LEAF to maintain speed? It has 1 gear so no changing is necessary. It reads power on the fly, so it knows how much is being consumed to add more to the throttle if necessary. This should be an exact science unless going up or down the biggest of hills.

ztanos, that's what the LEAF does now. This thread is all about folks that may not want the LEAF to maintain speed, for efficiency purposes.

I think the LEAF does a pretty good job of maintaining speed, and that is what I want. If I want to vary speed for up and down efficiency, I hit the cancel button.

One of my pet peeves is drivers that yo-yo; especially on two lane 55 MPH secondary roads.

grommet said:

ztanos, that's what the LEAF does now. This thread is all about folks that may not want the LEAF to maintain speed, for efficiency purposes.

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:shock: Oops... wait... :?: so people don't want cruise control to control their cruising speed? :?: Then why use cruise control? :lol:

ebill3 said:

I think the LEAF does a pretty good job of maintaining speed, and that is what I want. If I want to vary speed for up and down efficiency, I hit the cancel button.

One of my pet peeves is drivers that yo-yo; especially on two lane 55 MPH secondary roads.

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+1

I think the point is to have the option to do either. On uncrowded hilly roads, an ECO mode allowing the speed some latitude gives better economy. In other situations a normal mode can hold speed more closely, at the cost of efficiency. That allows prioritizing on traffic or efficiency as conditions dictate. Why not have both?

KeiJidosha said:

Why not have both?

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Mr. KeiJidosha (if that is your real name),

Damn you, DAMN YOU ALL TO HELL !!! How dare you interject rational, reasonable prose in an internet forum ?











:mrgreen: