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The Torque Pedal

Discussion in 'Roadster: Technical' started by TEG, Jul 1, 2007.

  1. TEG

    TEG TMC Moderator

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    In a conventional ICE car, the accelerator pedal is commonly called the "gas pedal" (at least in the USA).

    This is obviously inappropriate for the Tesla Roadster, so I think we should call it the "Torque Pedal".

    I thought to just call it the accelerator pedal, but in the Roadster it can also cause deceleration when you let off due to regen.

    In the Roadster, the pedal apparently sends a motor torque request to the PEM. The torque request goes from negative (for regen) to positive depending on pedal position.

    (If the eMotor is above a certain RPM the PEM may restrict how much torque it actually asks the motor to make to make sure the eMotor stays happy)
     
  2. AGR

    AGR Member

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    You could call it the Torque Pedal... 8)

    On a different note, will the brake lights turn on when you let off the positive torque, and get on the negative torque(by getting off the accelerator)

    The regen braking when you get off the Torque Pedal and the car starts slowing down without the brake lights coming on presents an opportunity to get "rear ended" in a traffic situation.
     
  3. tonybelding

    tonybelding Active Member

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    I'm sure I read somewhere that regenerative braking activates the brake lights.

    I still like "accelerator" pedal. Einstein taught us that acceleration and deceleration are the same thing anyhow -- it's al relative. :)
     
  4. vfx

    vfx Well-Known Member

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    Torque Pedal.

    I like it.

    It differentiates from the common "gas" pedal but not in a super-nerdy way that would put people off.

    Torque is a powerful word that really says something positive. It conveys movement and energy expended. It's also not so far out a technical word that Mrs. Jane housewife in the Midwest would not accept it. She would know that Torque is a "mechanical thing" but would not be confused or afraid of it.

    Personally I have bee saying Accelerator -a word that is too long and too much of a mouthful.

    Sometimes I use throttle which is pretty a good word but the only use I would have for that word besides in a car would be to describe the act of beating someone up (not a good association)

    The word Torque is short, strong and MANLY with the harsh "T" and Q as a "K" sounds. When written the “ Q” itself looks a bit effeminate but since it’s not pronounced like the “Q” (QUA) in “Queen” but as a (KUH) sound it's OK. Combined with the (TUH) of the opening “T” the whole the word is very rugged and powerful

    I would ask for it to be proven that the term Torque Pedal is technically accurate definition of what it does and why a "regular" ICE car pedal could not make the same claim.

    Still though, I submit that all Tesla documentation and Marketing and Sales teams* adopt the term “Torque Pedal”. In fact, all future manufactured EVs should consider standardizing this important differentiating term.



    *Like that Tesla guy in the UK showing the light blue Roadster in the video.
     
  5. TEG

    TEG TMC Moderator

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    Have you visited the latest Tesla blog page? ;)

    TeslaMotors: "A torque command is derived from the position of the throttle pedal. The motor controller converts this torque command into the appropriate 3-phase voltage and current waveforms to produce the commanded torque in the motor in the most efficient way. The torque command can be positive or negative. When the torque serves to slow the vehicle then energy is returned to the battery and presto - we have regenerative braking!"
     
  6. doug

    doug Administrator / Head Moderator

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    In general, I'm not a fan of inventing new terms when there are existing terms that are perfectly adequate and accurate. A change in velocity is an acceleration, be it positive or negative, so I would just call it the accelerator… something everyone understands.

    I agree that “gas pedal” is inappropriate for obvious reasons. For that matter, “throttle” is also inaccurate since a throttle is literally something that regulates the flow of a fluid (either gas or liquid). But to use “torque pedal” doesn’t really add much and there’s no reason you couldn’t just as easily use that term with an ICE car. So again, I’d stick with accelerator.


    "It can't be that difficult to figure out which pedal is the velocitator and which is the decceleratrix." -Mr. Burns
     
  7. doug

    doug Administrator / Head Moderator

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    I don't remember hearing about it from Tesla directly.  You might be thinking about the brake lights on the ACP eBox (fourth paragraph here).  As I recall, it took them some time to work out the appropriate deceleration threshold for when the brake lights should come on.  On the first iteration the brake lights came on too easily and adversely affected the behavior of the vehicles traveling behind.  The ACP eBox also has a little driver adjustable knob to control the level of regen, something Tesla seems reluctant to do for some reason.
     
  8. AGR

    AGR Member

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    The safety aspect of regenerative braking can become an issue. I certainly would not like to follow a vehicle where every time the driver takes his foot of the TorQ Predal or Accelerator that brake lights come on, with no idea of when he is putting his foot on the brake pedal.

    There could be "regen buttons" on the steering wheel, which could be similar to downshifting a car with an ICE and a transmission. There could be several regen positions on the buttons, and once the TorQ pedal is depressed the regen positions defaults to 0.
     
  9. TEG

    TEG TMC Moderator

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    By the way, the Prius & other Hybrids have an extra regen "gear" setting. So you can pick "D" for regular drive, or "B" for drive with enhanced regen.
    Tesla apparently bumps up the regen when in 1st gear (as apposed to 2nd), but the Toyota system is purely a different software profile as they have a CVT gearbox.

    The "throttle" term really does go with ICEmobiles. Old carburetors had "throttles" and "chokes" to basically starve the engine for air. The terminology goes so far to talk about engine breathing, etc.
     
  10. Michael

    Michael Member

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    I would think that letting up on the GO pedal should do nothing more than provide a similar feeling to that we would currently get by letting off the pedal on an ICE vehicle.

    Pressing on the Brake pedal should be the only way that the brake lights activate, and the amount of pressure applied to the Brake pedal should control the amount of additional regen given up to the point that the batteries are incapable of accepting further input, at which time the braking switches over to physical brakes.

    The above allows the current driving dynamic to remain consistent with what most people are already comfortable with and requires no further safety concerns with regards to when and how much a vehicle slows down and when the brake light should activate.
     
  11. TEG

    TEG TMC Moderator

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    I was driving in an old hot-rodded Camaro. It had a monster V8 with very high compression engine. The amount of engine braking on it was huge. When you stepped on the gas it shot forward with a vengeance. When you let off on the gas pedal it slowed very rapidly. The amount of engine braking on ICE cars can vary quite a bit. There are no brake lights involved with that.

    Also, the ability to hold on a hill varies. When I drive a stick (manual trans) on the hillls in San Fran I hate it when the auto trans ICE vehicles pull up right behind me because they don't realize I might need a bit of "roll back" room to get the clutch worked out to start going when the light changes.

    I don't think there is an exact formula to know how much regen is OK before brake lights should be applied. Hopefully Tesla can work this out.
     
  12. AGR

    AGR Member

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    Releasing the TorQ Pedal (accelerator) should not initiate a braking action (regen) its counter intuitive to what the driver would expect.

    Comparing an ICE car with a high performance engine, a manual transmission, and tall (numerically high) rear axle ratio and how it behaves in a lower gear if the driver purposely gets on and off the gas is similar to a Roadster in first gear with the driver putting the TorQ Pedal to the metal and releasing it (going from full positive torque to full negative torque. Sinking a passenger in the seat, and then hanging him off the seatbelts.

    Regen should be "subtle" comparable to an ICE car with an automatic transmission in high gear, if regen is more aggressive then the ABS / traction control must be programmed in such a fashion that if there is impending lock up of the rear wheels or one rear wheel regen will immediately deactivate.
     
  13. TEG

    TEG TMC Moderator

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    The Roadster has a manual trans (of sorts). People with manual trans ICE cars expect some amount of engine braking when you let off of the pedal with the car in gear.
    The amount varies based on engine displacement, and other factors. With the torque of the Roadster it acts like it has a really big ICE. So, it shouldn't be too surprising to have some real engine braking feel when you let off on the torque pedal.

    I think you would be surprised how many people would quickly get used to strong regen and enjoy driving twisty mountain roads just using one pedal most of the time.
     
  14. AGR

    AGR Member

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    Most high performance driving schools instruct people to actually use the brake pedal and obvious the brakes. If the Tesla Roadster customer is in his 40's and up, they will use the brake pedal and brakes.

    Not to be contradictory here, how many people actually live in an area where they would have to negotiate 3 to 5 miles of twisty mountain roads, going up in one direction, and going down in the other.

    Regen is an interesting feature of electric cars, similar to downshifting being an interesting feature of ICE cars. The reality is that most folks (99%) have an automatic transmission and use the brake pedal, its simpler than downshifting and then braking. By using the brake pedal the ABS system will immediately come into play if required. Since most folks do a lot of multitasking in a car, where actual driving almost takes a backseat to whatever other activity has a higher priority, they will use the brake pedal first, downshift or regen second, and if regen is too high to their liking they will immediately visit the dealer and have it altered or disconnected on the premise that its an unsafe feature for them. Especially in climates that have snow, ice, freezing rain, black ice.
     
  15. TEG

    TEG TMC Moderator

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    Well, I mention twisty mountain roads as the ideal place for the heavy regen, but it is nice even in stop and go traffic.
    I put my electric truck in "economy mode" (with higher regen) and can keep off the brakes in a lot of low speed freeway commute traffic.

    I tried to make a case for improved driving dynamics, but the real reason is to keep the efficiency up by maximizing regen and saving the brakes for emergency stops.

    If we tell people to drive EVs just exactly like they drive ICE cars, they aren't getting the full benefit.
     
  16. AGR

    AGR Member

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    TEG,

    You make a valid point, and IMHO the car should have a "driver adjustable regen" feature like RL (regen light) - RM (regen medium) - RH (regen heavy) that a driver can adjust to their personal preference / level of comfort.
     
  17. W8MM

    W8MM R1.5 #325 + Mdl S #01380

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    I'll be 58 by the time my Roadster is delivered and I think I'll be able to figure out how optimize regen braking just fine.

    I can do it in my kids' Civic Hybrid like it's second nature.
     
  18. Michael

    Michael Member

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    I do believe that by using the brakes as a way to address how much regen is involved, people will be able to drive the EV the same as an ICE and still get the full regen benefit possible from the EV.  Having a small amount of regen by letting off the Torq pedal should simulate what most people currently encounter; e.g., they can begin the slow down process, then the amount of pressure applied to the brakes controls how much additional regen is applied.

    If someone in front of me begins slowing down at a significant rate without their brake lights coming on then I will be at a disadvantage in terms of being able to maintain a safe distance from them and actually being aware of them beginning to slow down.
     
  19. bikergod

    bikergod Member

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    Yes torque pedal works. I recently reread some of Tesla's press release's and when they used the term "accelerator pedal" it just did not seem appropriate. Saying accelerator pedal would be like saying I took my Tesla out for a spin and "really gave it the gas" UGH!!
     
  20. W8MM

    W8MM R1.5 #325 + Mdl S #01380

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    I asked about this while touring Tesla HQ many months ago.  I was told explicitly by a guy from engineering development that this would NOT be the case.  The drive torque and regeneration control was solely via the long, thin pedal; no regeneration through the brake pedal. 

    I asked why they took that decision and was told that keeping the friction brakes and electric items completely separate was how Tesla preferred to design the system.  They felt that there were vanishingly small benefits if the two systems were integrated and the engineering and regulatory burdens were not worth the effort to combine them. 

    I took away a feeling that they value simplicity of systems as a means of getting to market on time with something that actually works well.
     

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