Cruise Control (with MPG sensitive logic)

[fjasper]

This was probably covered elsewhere, but I didn't see it in this thread.

With the Audiovox aftermarket cruise (and probably others), if you set the sensitivity to the lightweight, high-powered vehicle setting, it makes it less sensitive to changes in speed, adding less throttle when you slow down and letting off less when you speed up. If normal cruise gets to full throttle at 3mph below the set point, with the alternate setting, it might not get to full throttle until it's 10mph below the set point. It's not DWL, but it's better than the default setting.

With an automatic transmission that doesn't lock up, using the ignition signal instead of the VSS will give you a little bit of the same thing, letting the car slow down more when there's more torque required and speed up more when there's less torque required.

If the vacuum throttle actuation isn't working very well, you can either put on a vacuum reservoir with a check valve or add a vacuum pump. Some older European cars used an electric vacuum pump to operate the cruise control because the relatively low-powered motors didn't make enough vacuum at highway speed to reliably operate the cruise. The pumps aren't expensive (used) and are easy to hook up.

The throttle lock is safe on a motorcycle because you can positively close the throttle, even if there's extra friction. In a car with a spring-return throttle, it would take an additional mechanism to make sure you can positively close the throttle if you lose control of the throttle lock.

Or just be ready to take it out of gear (or switch it off without engaging the steering lock) and pull over. Which isn't that hard if you're ready for it, but can be disconcerting if you're not.

[bnmorgan]

Ok, maybe i missed it along the way, but what's the difference here between using the MAP like you're talking and using the engine load to regulate it. the logical conversation with the microcontroller being something like
"when speed < CCset, increase throttle until speed= or > CCset or until Load 80% "

or something along that line. that way you don't immediately peg to max load like my little TDI does on some of our hills around.

[steffen707]

Hey jomelmaldonado, what's your progress on the arduino based smart cruise? I know those mpguino guys could whip up some code. They probably would have to design new hardware though cuz it only has 2 inputs already for vss and injector.

[jomelmaldonado]

Hello and thanks for asking, as a matter of fact, I managed to finish the load sensitive cruise control using an Arduino controller, under a research proposal of the National Science Foundation. I used the vacuum sensor as long as the speed was maintained withing an upper and lower limit. As soon as it went out of the limit, the system returned to normal operation to control the speed, until it again reached the speed limits. The system works fairly well, but still needs some refinement, I am using a PID algorithm designed by me, but I need some help in such program, so anyone out there that has any ideas will be greatly appreciated. I am including a Scribd link to the power point presentation I had to make for the NSF Symposium offered on March 12, 2011.

Load Sensitive Adaptive Cruise Control

I am also including a Youtube link of the video when I presented, it's in Spanish.

Video of the presentation

Hope this information is helpful and any ideas, just let me know.

[steffen707]

That is awesome! Way to come through with this. Are you planning to let others use your arduino code? Are you planning to sell kits or something like the pre-built mpguino units? I totally want one, and will pay for it as well.

Congratulations, i look forward to reading the powerpoint and watching the youtube video!

[jomelmaldonado]

Well not for now, since it still has to be refined and the PID parameters have to be adjusted for a better response.

I decided to post this information here at ecomodder since it has been the source of information and inspiration for my on going project, thanks to all of you, the ecomodder members, that contribute in some way or another with tips and advice and valuable information, this is my way of saying thanks.

Perhaps in the future, I will decide to sell the system, but not for now. As a matter of fact, if anyone of you has any idea how to improve or implement a PID controller using discrete control, please let me know.

[bnmorgan]

How will it work for vehicles without vacuum? (Such as my diesel, where vacuum is artificial and not variable based on the engine and it's operating parameters)

[jomelmaldonado]

Well for now, the system doesn't provides control for diesel engines, since they doesn't have a throttle and don't produce vacuum. If there's a way to measure engine torque or fuel flow, maybe it could be modified to receive that signal to control the load.

[bnmorgan]

I have a scangauge, and it does have a "Lod" (load %) display, so it's there somewhere.

[jomelmaldonado]

Hey bnmorgan, that load value that displays in the Scan Gauge is a calculated load, based on the fuel flow and the size of the engine, but it can be used as a process value to modulate engine load.