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Automatic creep makes it impossible to come to a smooth stop

Discussion in 'Roadster: Technical' started by Stuart, Oct 4, 2011.

?

Do you want creep or no-creep?

  1. No creep - the car doesn't move if the accelerator isn't pressed

    45 vote(s)
    60.8%
  2. Creep - the car rolls forwards if the accelerator isn't pressed

    29 vote(s)
    39.2%
  1. Stuart

    Stuart Roadster#326, ModelS#1409

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    Below is a suggestion I made to the good people at Tesla. They requested I post it it to the teslamotorsclub forum because they're interested in seeing how much support there is from other people.

    I like to drive well. One of the things I was taught when I was learning to drive is that if you're in control of your vehicle then you should be able to bring it to a smooth stop without any perceptible lurch, by gently letting off the brake pressure as the vehicle slows down to a smooth stop. In a manual transmission car if you depress the clutch pedal and brake properly you can do this.

    For design reasons I won't speculate about, the Tesla Roadster was designed to emulate an automatic transmission. With no pedals pressed, if it is in drive, it will slowly creep forward, presumably to remind the driver that it is still in drive. However skillful you are on the brake pedal, if the car's motor is trying to make it go, it becomes impossible to bring it to a smooth stop without a small lurch.

    I have read discussions about disabling this "automatic creep", but I'm realistic enough to realize there are probably good reasons Tesla wouldn't want to do that. (I have also read discussions about hacking firmware to disable the "automatic creep", but I don't want to do that.)

    This led me to wonder if there could be a way that car could let the driver stop smoothly without having to disable the "automatic creep" and a compromise occurred to me: If my foot is on the brake pedal, and the brake lights are illuminated, then the car's electronics know that I'm trying to bring the car to a stop, so why are the car's electronics fighting me and trying to make it go? Would it be possible to make the car's electronics disable the "automatic creep" as long as the brake pedal is depressed? That would allow the driver to bring it to a smooth stop. If the brake pedal is then released then the "automatic creep" would resume, to remind the driver that it is still in drive.

    Does that sound like a sensible compromise, to allow good drivers to drive well, while still retaining the safety requirements of "automatic creep" so that driver's can't forget that the car is still in drive?
     
  2. TEG

    TEG TMC Moderator

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  3. TEG

    TEG TMC Moderator

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    Some cars may keep a little power to the drivetrain to keep the gears "loaded up" so when you start moving there is no "clunk" from the gearbox.
     
  4. Stuart

    Stuart Roadster#326, ModelS#1409

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    Yes, I plead guilty to that charge. I am probably guilty of being too much of a perfectionist, and not just in my driving habits. I have seen lots of "creep" vs. "don't creep" discussion, with suggestions for mode settings to choose one or the other (ugh!), but what I hadn't seen before was a proposal that might make both camps happy at the same time. What do you think of the "creep, but not if my foot's on the brake pedal" idea?
     
  5. Eberhard

    Eberhard #421 Model S #S32

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    Stuart, you have simple push the "N" Button, then the creep is being switched off as well.
     
  6. Stuart

    Stuart Roadster#326, ModelS#1409

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    Yes, understood. In my 2008 model it's a gear-shifter rather than a pushbutton, but the idea is the same. Still, futzing with the car's controls is an unnecessary hassle. I work at Apple, and we put a lot of thought into user interface. Surely when my foot's on the brake pedal the car electronics should be smart enough to know that my intention is to stop, not creep forward?
     
  7. Dragon

    Dragon Lightning Green Fairytale

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    I honestly don't see the problem here. The creep is very minimal and if you brake you'll stop regardless if there is a creep or not?
     
  8. TEG

    TEG TMC Moderator

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  9. meloccom

    meloccom Moderator Aus/NZ

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    #9 meloccom, Oct 5, 2011
    Last edited: Oct 5, 2011
    Actually, there is precedent to this. My A160 Merc has the auto clutch feature and it , the computer, releases the clutch when you press the brake pedal at low 'manouvering' speeds giving a similar effect to Stuart's idea for the roadster. When you release the brake pedal, such as when manouvering or at traffic lights it has a creep feature.
    I like this feature and the fact that it is cancelled out by the brake but additionally you need to add an additional rule to overide yours when using 2 pedals for tricky situations like reverse parking up a hill on a road with strong camber. In my Merc I have to be very aware of it's tendancy to speed up when i roll down the camber into the spot if I use 1 pedal.
     
  10. AnOutsider

    AnOutsider S532 # XS27

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    Not a horrible idea, as I find myself wanting to drive as smoothly as possible as well (which is near impossible in AT cars that creep). As for why Tesla added it in the first place, it could be the whole "keeping the gears engaged" mentioned, or maybe an effort to make the cars feel as close to "normal" as possible to lower barrier of entry for people new to EVs?
     
  11. Mycroft

    Mycroft Life happens

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    I agree 100%. If your foot's on the brake, there should be no creep. It doesn't make sense. The brake light goes off, then start creeping.
     
  12. VolkerP

    VolkerP EU Model S P-37

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    I second that. Mimicking inefficient ICE behavior should be dumped from a 2nd generation EV.
     
  13. vfx

    vfx Well-Known Member

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    Really thinking about this it's a very good refinement of what Tesla is doing and is right up the ally of them trying to make a car that is the best on the road.

    So the problem is when we are coming to a stop at the very last 1 or 2 miles an hour the creep takes over changing regen's somewhat linear downward speed ramp to a straight line speed before it can complete it's path to a complete stop. Since there is no way to predict exactly when it that flat line will "jump in" you can't react fast enough and change your braking amount to the new speed to achieve an ultra smooth stop at that very very end of the braking.

    Another solution would be to not have creep come on till after the car comes to a complete stop BUT,

    As a certified "creep hater" what I don't like about it is when sitting at a stop light and you relax your brake foot a bit the car starts lurching forward. Even with the brake light still on.

    So yes, your idea works for me as a solution that is closer to what I want than we have now. Who knows, I may even like it in practice.

    As long as the brake lights are on, creep is disabled. It would make for ultimately smoother final end of braking and make the car not be too anxious to move forward when slightly letting off on the brake while stopped.

    I find this to be superior to an AT ICE car. Tesla should implement this on all cars past and future.


    Good thinking!
     
  14. ckessel

    ckessel Active Member

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    This gets my vote as well. In a traffic jam where it's little bits of stop and go or at a long line for a stop sign, creep is nice when you take your foot off the brake (about the only case were an manual is more painful than an AT for me). However, if the break is depressed at all then I don't want creep fighting it.
     
  15. hcsharp

    hcsharp Active Member

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    I think their reasons for doing it were primarily to emulate the behavior of an automatic transmission that most people are used to. I think another reason is that they want to keep the electric motor turning very slowly. An easy way to implement that is with the creep feature. To start a variable speed induction motor turning is a little tricky and easier with a known load. The PEM needs to get feedback from the motor to know how fast it's turning in order to control it properly. The first few milliseconds when it starts turning it has to guess at some of the normal feedback that it doesn't have yet. So if they have it spinning at a very minimal speed it's easier to just add power and get the car rolling vs starting the motor turning, then adding power. They could have the clutch disengage completely if your foot is on the brake while still keeping the motor spinning very slowly but that might be harder to implement.

     
  16. NigelM

    NigelM Recovering Member

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    Fine for considering only the stop; what about pulling way on an incline? I learned to drive in the UK where the dreaded "hill start" was part of the driving test but you got very quickly used to feeling the bite point (cars were all manual transmission back then). Is there no concern that without creep the car will roll backwards before you can accelerate away?
     
  17. vfx

    vfx Well-Known Member

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    No they argue that it's for safety. The idea that you can get out of the car while it's on was unacceptable to them.

    I don't think Tesla has any start up electric motor issues. Their control software and feedback encoders should completely negate this as a problem. It's not a washing machine.

    Clutch?
     
  18. davidrmay

    davidrmay Roadster 2.5 #1382; S85 Sig #117 & P90D

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    Definitely has my vote. not a fan of the creep. seems silly.
     
  19. jkirkebo

    jkirkebo Model S P85+ VIN 14420 EU

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    That is easy to fix. Just activate the parking brake if the drivers butt is removed from the seat when car is stationary ;)

    Personally, I like creep. It makes it easier and safer to maneuver slowly in tight locations, like in parking garages.
     
  20. Sparrow

    Sparrow S105/ Roadster 189

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    With your brake on and the car stopped, I don't think there is any creep anyways. When I look at my amp draw in my 1.5 when stopped it reads 1. When I let up on the brake and creep starts the amp draw is 3. I've got to believe that Tesla has already shut the creep off when you have the car stopped and your foot is on the brake. Not sure you can tell whether creep is on while coming to a stop, but I would have assumed so until this conversation started.
     

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