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Automating Pulse and Glide / Mod

Discussion in 'Gen 2 Prius Accessories & Modifications' started by Tekdeus, Dec 29, 2010.

  1. Tekdeus

    Tekdeus Shifted to Green

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    With the benefits of Pulse and Glide driving proven to yield 75+ MPG, I'm surprised there are no mods to automate this process. I've been contemplating ways to do this, and thought it would be worth discussing again (unless I've missed another thread somewhere).

    The two options I imagine are either electrical or mechanical, both modulating and setting the upper and lower throttle positions for optimal P&G:

    An electrical method might be to record the throttle pedal voltages at the ideal throttle positions(found by manually doing P&G), and somehow feeding those values back into the ECU at the right times, kind of like cruise control with upper and lower ranges.

    A mechanical method I thought of today would be to at minimum, have a mechanical low-position throttle-stop, so the pedal defaults to the "glide" position, instead of having to feather the pedal each time. I thought of using something like a bicycle gear lever to manually actuate a cable/wire that would protrude into the right position to stop the pedal from reaching zero. This throttle stop could be turned on or off easily depending on when the driver wants to use P&G driving. It would not be a safety issue, since it would only prevent deceleration regen while off-throttle. Similarly, a 2nd cable-actuated throttle stop could also limit the throttle to allow the perfect brisk acceleration ICE sweet-spot pulse back up to the desired speed. These upper and lower throttle stops would always keep the driver in the perfect throttle range, so the only task becomes flooring the pedal and letting off completely at the right times.

    Also, does the cruise control resume function use the throttle aggressively enough to be used for the "pulse" portion of the technique? Just wondering if the cruise control can be incorporated somehow.

    Any other ideas? This would be sweet to figure out!
     
  2. PhazonPhobe

    PhazonPhobe His name is Sora

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    My thoughts would be a sort of macro. Back when I used to hack online games, we would use macros for repetitive training methods, or getting a botting program to repeat certain movements or press certain keys.

    I haven't the slightest clue of how it could be done, but it would be similar to cruise control. Assuming you're going to be pulsing and gliding for a good distance, just as you would would turn CC on and "set" your speed, you would basically just record the positions of the gas pedal.

    IE:
    1. Turn cruise control (or w.e would be used for the recording)
    2. Push "Record" (or "set" or w.e)
    3. Pulse from, say, 34 to 40
    4. Glide down to 34
    5. Push "Set" (or "Stop" or "Record" again)

    The macro would just need to loop itself. Pulsing up to 40, gliding to 34. Etc etc.

    There should also be a way to "Resume" in case the driver were to need to brake or what not. Essentially press "Resume" and it would get back up to the speed the macro recording started, then it would just continue repeating the macro of pulsing and gliding.

    Edit:

    Didn't read your post entirely. =X Hadn't realized what you said was very similar to my post. Sorry
     
  3. JimboK

    JimboK One owner, low mileage

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    Great idea if you can make it work.

    By "throttle" it sounds like you're actually referring to the accelerator versus engine throttle. The Japanese hypermilers have reported a pedal position of 38-40% (as reported by the CAN bus) to be optimal for pulsing. I'm not sure how practical that is, however, for most of us. I am constantly making making subtle (or occasionally not-so-subtle) adjustments in pedal position depending on speed, terrain, following traffic, and HV battery state of charge. I am not driving in the typical conditions of the Japanese drivers (who have exceeded 100 MPG in a tank), so there really is no one sweet spot for me.

    Some have used cruise control to pulse: 1) Set it at, say, 35. 2) Glide to a speed of your choosing above 25 MPH (at which CC deactivates on its own). 3) Resume CC. But the problem is not whether it's aggressive enough; it's too aggressive, sometimes pushing RPM to 3000 or higher, well above optimal efficiency ranges for the ICE. And the 25 MPH cutoff is another limitation for me. I plan my routes to take best advantage of low-speed P&G where I routinely glide down to speeds of <25MPH.

    Now, if you can figure out how to tie it to some direct or indirect indicator of ICE loading (e.g., RPM or injector timing) with some sort of CC-like control, then you might really be on to something.
     
  4. Rokeby

    Rokeby Member

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    Interesting idea. Can't be an easily done thing given the intense
    scrutiny, attempted hacking/work-arounds that the Gen II
    HSD/control algorithms has been subjected to over the years

    On the electrical side, the go-pedal sends at least 2 signals which
    are constantly monitired and compared not just for position but for
    rate of change. I suspect it would be very difficult to finesse a false
    signal stream. As I understand it, garbage in and the ICE shuts down
    as a safety measure.

    As to the cruise control, small differences between the set speed
    and speed when re-engaging result in the computer trying to make
    up the difference very quickly, with RPMs typically going well past
    2800 RPMs and fuel efficiency drops off dramatically. IIRC, it does so
    starting at ~2400 RPM. For this reason, before I re-engage the CC,
    I accelerate podially -- ?? manually ?? -- to just above set speed.

    FYI, here is a previous thread that pertains:
    http://priuschat.com/forums/gen-ii-prius-modifications/53700-throttle-glide-postion-button-mod.html

    Although not reflected in the in the thread, I was having a PM
    discussion with Hobbit on the topic. From him I came it have an
    inkling of the complexities of the go-pedal electrical system/signals.
    He thought that a mecanical arrangement would be a real kludge,
    and unlikely to be truely workable.

    Separately, I wonder what has become of Hobbit, lo these many
    months without a post. I miss him, and I pray that he is all right.
     
  5. Tekdeus

    Tekdeus Shifted to Green

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    For a sure-fire 25-30 gain in MPG, I can't believe no one has found a solution for this. That Blitz controller listed on that other page shows that it is possible to effectively manipulate the TPS signal to the ECU, perhaps there is already some module in Japan that does this? After all, the Prius IS the #1 selling car over there!

    There's bound to be a mechanical solution from a giant parts place like
    McMaster-Carr

    Here's some possible hardware I found here:
    McMaster-Carr cable controls

    Precision Knob Controlled—Turn to Lock
    "Turn to lock is perfect where severe vibration is a concern. Just pull and turn the handle to its locking position. Precision has a vernier knob for fine-tuning throttle positions."
    5 ft. 0.31" 0.085" 3" 30/30 8" ___ ___ 2" 3/4"-16
    Cable Cable Core Stroke Push/Pull Bend Lg. Ht. Dia.
    $37.09
    [​IMG]
     
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  6. 2009Prius

    2009Prius A Wimpy DIYer

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    That's what I was thinking also. Someone (Hobbit?) said IGN 14 is good for efficient pulsing. I find it relatively easy to hit IGN 14 except when it's very cold out it would be pegged around 12 no matter what I do with the accelerator (I haven't tried flooring it - don't think that would save any fuel). Anyone with similar experience?
     
  7. ystasino

    ystasino Active Member

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    I can't contribute any technical expertise here, but I have wanted this for years. I have wondered how Toyota never thought of this, or whether they never applied it to avoid cannibalizing their other hybrids.

    Well you all have my support on this :)
     
  8. bisco

    bisco cookie crumbler

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    perhaps it would not be legal.
     
  9. Tekdeus

    Tekdeus Shifted to Green

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    Has anyone had experience using solenoids and know how strong they are? I posted this in the other thread, and was hoping to get some feedback before I started spending money on "experimenting". Also, I'm seriously thinking about using a solenoid like this "laterally"; meaning that it sticks out from the side, just enough to block the very top of the pedal from returning to zero; in which case a 2nd solenoid could also activate to limit the max throttle position to the optiomal "pulse" position of approx 38%. Just a toggle button on the dash would stick both solenoid shafts out, giving the driver upper and lower throttle stops; all he has to do is use his foot max/min to pulse/glide optimally. I'm hoping to get a suggestion on a solenoid, or some kind of sturdy lateral shaft/piston assembly that could push out, but hold its position accurately with the heavy lateral load of the pedal.

    ***
    (as a "glide" throttle stop) What do you guys think of this? I'm wondering if this would be strong enough to push on the top part of the plastic throttle pedal lever near the top pivot. Up there is out of the way, but requires the most force because of the leverage. Also, do you figure it would be Ok to energize a solenoid like this for long periods of time without concerns of overheating or electrical consumption? This one is designed for A/C throttle usage so I am assuming it would be.

    The other idea I had with using a solenoid for this mod was to have it come in from the side, just enough to block the pedal from returning to zero. This would require something to hold force laterally, with enough precision to get it in place. Also, if greased, it may be possible for the solenoid to spring back into off position. Any suggestions on hardware that would work for this?

    Holley 46-74 - Holley Universal Throttle Solenoids - Overview - SummitRacing.com
    "These universal throttle solenoids from Holley are used on vehicles equipped with air conditioning. They automatically bump-up the idle speed of the engine when the A/C is switched on."
    [​IMG]
     
  10. BentSpace

    BentSpace Member

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    I was contemplating this same idea on a long road trip I just took.

    So, no way to connect a laptop to the prius and control the throttle?

    Then you could write a simple program to do it.
     
  11. krelborne

    krelborne New Member

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    I'm sure Google could tell you how to do it.

     
  12. FreydNot

    FreydNot Member

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    I always thought it would be a good idea to make an automated system that works by adjusting the cruise control. The driver would set a desired speed on the cruise control like normal and when the car started pushing the engine faster than is efficient (as it tends to do going up a hill), the system would detect this and lower the cruise control set point until the injector pulse length is back into optimum. When the car slows down and there is some head room, the set point can be adjusted back up until either the pulse length is too long again or the operator set point is reached.

    Adjusting the cruise up and down should be as easy as intercepting the wires from the cruise control stock. The hard part will be reading the set point. If the cruise control data is available on the OBD port, it could be pretty easy.

    Another benifit is if the whole thing goes wacko all you have to do it tap the break or otherwise disengage the cruise control.

    Not exactly P&G, but it sure would help the MPG. Just a thought. If you implement it, I would like a free unit as a finders fee; I'd even participate in the testing. :)
     
  13. mikewithaprius

    mikewithaprius New Member

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    I like to pulse on my own, I just want there to be a glide button. This is slightly different than neutral, since the glide still gives a little battery oomph to push the car along, as most of us know.

    I can only assume it's not as easy as this, I'm guessing you guys who know what you're talking about (in direct opposition to myself :-D) would have thought of this - is there anyway to fool the computer regarding percent of gas pedal depression? A glide is definitely a very small but fixed range with the pedal, it seems as though a button telling the car it's at 7-10% (or whatever it is) could do the trick(?).
     
  14. ccdisce

    ccdisce Active Member

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    Messing with the Go Pedal output could have Legal issues.

    I see no reason other than the above why it cannot be manipulated inexpensively.
    A few months ago there was a thread on the subject which informed that there was a device available which could change the TPS vs Output curve, unfortunately the cost then was around $400.

     
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  15. BentSpace

    BentSpace Member

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  16. Velo781

    Velo781 Junior Member

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    I've been thinking about a mechanical system mentioned by the OP, to keep the systems in glide mode. It would apply just enough pressure via a bicycle shift cable to the accelerator to get it in glide. I'm still really new to driving the Prius, but it seems a little tedious to use your foot to apply that correct amount of pressure when desired. I'll report my results and design if I try it out.
     
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  17. bisco

    bisco cookie crumbler

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    you could throw it into neutral.
     
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