Drive-by-Wire: Simple Cruise Control Project Idea

Discussion in 'The Projects Forum' started by 1point9turbo, Oct 12, 2016.

Proceed with project?! Or pony up and just buy an aftermarket system?

  1. Fun Project

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  2. Boring Bank Account drain

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  1. 1point9turbo

    Thread Starter New Member

    Oct 12, 2016
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    Hello! Very first post here. Bear with me, I am not an engineer by trade. I am a Pilot for the USAF with an interest in many different hobbies... and I know my way around a soldering iron!

    So, I am an American living in the UK. The cars are much different over here. Many of them are very basic for the purpose of removing driver distractions. The English are very particular about distracted driving.

    Thus, I bought a simple, inexpensive car since I will be here only about 2 to 3 years. It does not have cruise control, sadly. Now, a lot of the roads don't require it but I have a few reasons I would like it.
    1. It's a small car, my knee hurts to drive based on the position I am in. Even after about 10-15 minutes.
    2. The English get fined heavily for speeding and there are speed cameras EVERYWHERE. They have no problem with Big Brother here.
    3. Aftermarket Cruise Control systems cost about 340 to 360 GBP plus 100 GBP for install (about $550 total) and are complex in operation. Many use wire taps and are not plug and play or easily removed. I will have to re-sell the vehicle when I leave since I can not take this model back to the US.
    4. This model has no Ford Factory options (even though similar models sort of do...)
    5. It would be fun to come up with something (heeding to safety concerns)

    It is a drive-by-wire car with a small 1.6 TDCi Diesel engine. My idea is to basically have a remote throttle on the dash that mimics the same outputs as the accelerator pedal. When switched on, it would remove power from the floor pedal and transfer it to the dash mounted one (safety plan to follow). I am thinking begin with an actual accelerator pedal from a used car (can get very cheap), remove everything and get just the electronics out of it.

    In the aviation world , when we fly without moving the throttles or adjust power, we call it "flying a fuel flow" (or something along those lines). This would be the same thing. Instead of using a speed sensor on the transmission or axel, it would simply hold the throttle at a constant position that you can vary. Instead of holding a speed, going up and down hills would cause speed variations. I actually prefer this and wish more Cruise Control systems operated this way. It is more efficient if you let your speed bleed down slightly when going up a hill and then use gravity to re-accelerate you on your way down. We sometimes fly this way. Sometimes you don't have to brake or pull power and waste the energy that you've already created.

    As far as safety, it would require a switch that would release when you step on the brake... the same way it would in a normal system. So, you could hit the brake and return control to the floor pedal or manually switch it off. At first I figured I would have to build some kind of amplifier to get enough current to release a switch from the brake sensor (if I went that direction) but then thought I could just tap into one of the leads from the brake lights. This could possibly be accomplished with a tap from the fuse panel. In the airplane I fly, we still have some analog systems. The autopilot is one of them. So, if the airplane is making too many inputs or an input is required that it can not handle, a signal is sent to the switch to simply click it off and give manual control back to the pilot (sometimes without warning!). That is what I envision when I step on the brake. The switch clicks itself off returning control to the floor pedal. (Some kind of relay could probably accomplish all of this too but I would prefer as few parts as possible).

    Concerns: I don't want to get too deep into this car trying to figure out its software or anything. That is why the more electro-mechanical, the better. It is not a very popular vehicle to mod or tune haha. It is a 2007 Ford Fusion (JU2). UK version, not US. It's hard to even find replacement parts for. I am worried of what would happen if there is a momentary break in the accelerator pedal sensor (from switching back and forth) or if it calibrates itself when you turn the car on (would it even matter?). I am afraid the car could throw a code or turn off or something. I don't want to test it yet since I have no way of clearing the code on mine. I am not sure how long the sensor would have to be show as "removed" before the engine shows a fault. I am guessing even a small break could potentially cause issues. Another concern would be what happens if it does show a fault, would it allow a "re-connection" without turning the car off and on? Many of the sensors usually have to be faulty for a few times before the computer throws a code. I used to have an old VW Diesel and this seemed to be how it worked. Many times as a young tinkerer I forgot to plug things back in until I saw a code for it...

    Sorry for the long read. Any thoughts on if it's even worth a try? I figure another cool feature would be that you could set the engine to idle at a higher RPM even while parked. In application, start the car, clear off ice or snow, then hopefully have more heat before you drive off? VW had a similar feature on early TDI engines but I am not sure how successful it was. If you have never driven a small diesel engine car before, they take forever to heat up. In the winter, many people arrive at work before they even have any heat.

    If you read this far, thanks! Could be fun and be an application for many drive-by-wire cars.

    Cheers!
     
  2. jpanhalt

    AAC Fanatic!

    Jan 18, 2008
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    Can you wait until after November 8th? The Brits can be mighty nasty with anyone who messes with their cars. You may want to wait until you know you have a way out.

    John
     
  3. 1point9turbo

    Thread Starter New Member

    Oct 12, 2016
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    Haha, your right... maybe I'll end up keeping this car a lot longer than I thought... :)

    In all honesty though, there is zero rush. It's all brainstorming at this point. Stemmed from seeing the prices of anything aftermarket.
     
  4. jpanhalt

    AAC Fanatic!

    Jan 18, 2008
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    I appreciate your aviation analogy. But ATC is a lot more lax on speed limits than surface police are. You can always blame a tailwind. I would suggest you base your speed control on wheel revolutions.

    John
     
  5. KeepItSimpleStupid

    Well-Known Member

    Mar 4, 2014
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    Figure out how the accelerator operates. I know one method is dual pots where one is increasing and another increasing. Melexis has some hall effect angle sensors, so that's a possibility.

    Cruse generally disengages when you press on the brake. Has buttons for accel and deaccel and of course set. Furthermore, it has the ability to "override" temporarily when pressing on the accelerator. Don't forget that it has a min speed that it will allow engagement.

    Get a manual and a pedal to see what you have to work with.

    Long gone is the magnets on the drive shaft and the vacuum motor on the accelerator cable.
     
    Last edited: Oct 12, 2016
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  6. KeepItSimpleStupid

    Well-Known Member

    Mar 4, 2014
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    Options her may be the CAN bus or a speed interface to the speedometer switch if it has one. CAN interfaces aren't cheap.
     
  7. 1point9turbo

    Thread Starter New Member

    Oct 12, 2016
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    Yea, we start going that route and we'll quickly reach the limits of my hobbyist brain bytes! Open to all options though.

    Also why I was just going to bypass all of that and just mimic the accelerator remotely. If I can find the connectors, I can completely remove it very easily for inspection or resale purposes. Half the aftermarket systems seem to be thrown together projects (albeit more refined).

    I'm not real worried about the advanced features of normal cruise controls. It would be interesting if the remote accelerator could simply set a minimum throttle setting allowing you to accelerate by pushing the floor pedal past that minimum set but then upon release, the throttle stays at least at that threshold. I.e., for passing someone and resuming your speed (throttle setting). Same rule for the brake application switching it off and returning all control to the floor.
     
    Last edited: Oct 12, 2016
  8. jpanhalt

    AAC Fanatic!

    Jan 18, 2008
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    I don't know anything about British cars (except they don't start in Minnesota Winters). CAN bus is pretty common. I can't imagine this endeavor without being able to deal with it. Anyone on your team, including yourself, familiar with microcontrollers?

    John
     
  9. BR-549

    Well-Known Member

    Sep 22, 2013
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    I believe your control strategy is probable. Unless all the inclines are the same angle and length.
     
  10. Alec_t

    AAC Fanatic!

    Sep 17, 2013
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    The main reason Brits don't customise their car controls is that insurers don't like such modifications, which present an unknown perceived risk. Insurers must be informed of modifications. They are likely to either (a) invalidate your insurance policy, (b) refuse to insure you or (c) jack up your insurance premium to an astronomical level. The police/courts clamp down heavily on uninsured drivers.
     
  11. 1point9turbo

    Thread Starter New Member

    Oct 12, 2016
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    i have no team, if you were referring to me. just a garage hobbyist here haha. i like to save money and learn at the same time. a 15 pound part and a soldering iron to gain some knowledge and have fun is worth it to me.

    lots of cars have cruise control... I know what your saying about the Brits but also don't know if that is factored into the insurance at all. I can find out.

    my job keeps me pretty busy so I can't make this a long term thing. I am not even sure I need CC, would just be fun to have and see if I can come up with something.
     
  12. crutschow

    Expert

    Mar 14, 2008
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    I think you will find that maintaining a constant throttle setting will cause significant variation in road speed on all but the levelest of roads.
    Try an experiment the next time you are on a rolling highway (I assume they have those in Britain), keep the throttle perfectly steady, and see what variations in speed occur.
     
  13. 1point9turbo

    Thread Starter New Member

    Oct 12, 2016
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    Yup, I am fully aware that I wouldn't be getting a fine tuned system that holds speed exact. I am expecting the variations. To the best I could hold my foot steady, I'm getting +/- 3 to 4 mph variation around here. If it gets real hilly, I'd prolly just take manual control anyway... that's the pilot in me and what I do with a lot of terrain anyway.

    I want to keep it simple and cheap... It's really just for fun. It's a cheap car, I'm cheap, and I like to know that I don't always have to go with a commercial finished product.
     
  14. joeyd999

    AAC Fanatic!

    Jun 6, 2011
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    A bungee cord on the gas pedal? :D
     
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  15. tcmtech

    Well-Known Member

    Nov 4, 2013
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    Being a drive by wire Ford vehicle the odds are the computer that controls everything is already programed with cruise control but the factory control buttons are just not installed.

    Or at least that's how most American vehicles are anyway.

    I have a pair of mid 90's Ford pickup that don't have factory cruise and the only thing I need to do to add it is get the parts from a donor vehicle for that system install them and plug them in.
     
  16. 1point9turbo

    Thread Starter New Member

    Oct 12, 2016
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    ...and safe! haha
     
  17. 1point9turbo

    Thread Starter New Member

    Oct 12, 2016
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    Yes. The Fusion UK version is hard to find stuff for. On a forum for the UK Focus, Mondeo, and another model, they all share similar electronics and engines. The problem I am reading is that even if you do source the parts that would make it work in a model that never had the CC to begin with, the dealers are very reluctant to flash the computer to enable the program. They would have to specifically enable it in 3 spots for it to work correctly (according to a UK focus forum... that charges you to be a member so I can't even ask a question :( ).

    I don't know if it is just a UK thing but I did have a little trouble in the US with a dealer and my F-150. I had to flash the computer before installing a tuning box in the truck and none of the dealers wanted to flash the software if I wasn't reporting any problems with the way the truck was running. In my case now, you would be asking them to enable functions on a car that never even had CC as an option. Maybe a chop shop could do it, but still finding the parts is still a challenge. I've read there is a guy who knows of 1 person successful with getting CC working on a car that didn't have it from the factory.
     
  18. crutschow

    Expert

    Mar 14, 2008
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    Rather than replacing the accelerator pot, you might try paralleling a resistance or pot.
    That way you would minimize any crossover problems and could possibly still accelerate the car with the throttle if needed, such as to pass.
     
  19. KeepItSimpleStupid

    Well-Known Member

    Mar 4, 2014
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    crutschow:

    My understanding that a single pot would not be reliable. Therefore one system I'm familiar with uses two, in opposite "polarities". one increasing and one decreasing with the amount of accelerator press.
     
  20. tcmtech

    Well-Known Member

    Nov 4, 2013
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    It's rare that I have any concern over safety but in this case having a homemade circuit that bybpasses the gas pedal just because you are cheap and a lazy driver seems like all around stupid and unsafe idea. :(

    Would you fly a jet in combat that had a critical control bypassed by a homemade circuit that doesn't do what the correct system should do? o_O
     
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