TMC is an independent, primarily volunteer organization that relies on ad revenue to cover its operating costs. Please consider whitelisting TMC on your ad blocker or making a Paypal contribution here: paypal.me/SupportTMC

torque vectoring in AWD Model S

Discussion in 'Model S: Driving Dynamics' started by mikevbf, Apr 12, 2013.

  1. mikevbf

    mikevbf Member

    Joined:
    Feb 11, 2012
    Messages:
    798
    Location:
    vermont
    When the Model S and X get AWD I assume Tesla will take complete advantage of all abilities an all electric implementation of AWD brings to the plate including torque vectoring. In the Mercedes electric SLS they take it one step further by powering each individual wheel. See the video:

    Mercedes SLS Electric Drive. Can Volts Ever Match Pistons? - CHRIS HARRIS ON CARS - YouTube

    Do you think Tesla will implement this ALL AWD (4 motors) system with toque vectoring in the Model S, Model X, or some far distant super car, maybe the new Model R? Do you see big safety and /or performance advantages of four separate electric motors (one for each wheel) over two electric motors (one for each axle)? All I can say, is after watching this video I am excited about Tesla/Mercedes future collaborations!
     
  2. stopcrazypp

    stopcrazypp Well-Known Member

    Joined:
    Dec 8, 2007
    Messages:
    7,050
    It'll be useful for track times, but not necessary for normal driving. Standard TC and ESC even with a single motor is more than enough for that.

    Torque vectoring like in the Mercedes is a nice idea for a super car though. For Tesla to accomplish the same thing with two motors would require differential based torque vectoring like in ICE cars.
     
  3. mikevbf

    mikevbf Member

    Joined:
    Feb 11, 2012
    Messages:
    798
    Location:
    vermont
    Ok now to reveal my complete ignorance in this area. How would toque vectoring relate, if at all, to dynamic TC where dynamic TC has both the ability to give power as well as take power away from wheels?
     
  4. Mark Petersen

    Mark Petersen Model S EU P71

    Joined:
    Jul 15, 2009
    Messages:
    240
    Location:
    Hørsholm, Denmark
    Hi mikevbf

    the different is that with Tesla the motor drive 2 wheels, where with the Mercedes there is a motor for each wheel
    so if one wheel is spinning, you only cout power to that wheel and not both
    this is especial useful when you are going round a corner as the outer wheel need to rotate faster than the inner wheel
    when you can controle the speed of each wheel you can then provide the correct power to each of them
    when you have one motor that provide power to 2 wheels you need to use some form of differential lock when going stright
    but this lock do not work when you are turning
     
  5. Raffy.Roma

    Raffy.Roma Active Member

    Joined:
    Jul 22, 2012
    Messages:
    3,209
    Location:
    Rome (Italy)
    Yes I agree with you. So also for Tesla the torque could be applied to each single wheel in a completely independent matter and the torque vectoring could be realized also for Tesla.
    @Mark
    I don't understand why Mark does not agree with us.
     
  6. Mark Petersen

    Mark Petersen Model S EU P71

    Joined:
    Jul 15, 2009
    Messages:
    240
    Location:
    Hørsholm, Denmark
    Hmm
    Well if tesla make the AWD with 2 motors you can do torque vectoring between the front and rear but you still need to do differential lock between left and right, it is still Way better than with a ICE
    And TC on an electric is just so much better, and a 4 moter setup is super car, to realy take avantage of 4 motor torque vectoring you need a race track
    But I will still be enjoing my future P85+ even that it only have 1 motor :)
     
  7. Raffy.Roma

    Raffy.Roma Active Member

    Joined:
    Jul 22, 2012
    Messages:
    3,209
    Location:
    Rome (Italy)
    I read that the future AWD Model S, unlike the Model X, will have 4 motors. One for each wheel. Does anybody know anything on this matter?
     
  8. snooper77

    snooper77 Member

    Joined:
    Mar 21, 2014
    Messages:
    50
    Where did you read that? I think that's not true.
     
  9. ecarfan

    ecarfan Well-Known Member

    Joined:
    Sep 21, 2013
    Messages:
    10,381
    Location:
    San Mateo, CA
    Source? That is not what Tesla has said.
     
  10. WarpedOne

    WarpedOne Supreme Premier

    Joined:
    Aug 17, 2006
    Messages:
    2,659
    Location:
    Slovenia, Europe
    Yes. We know is not gonna happen because in a real world it is a bad bad bad idea.
    AWD will be dual motor design .

    Torque vectoring only needs AWD, not 4 motors.
     
  11. Johan

    Johan Took a TSLA bear test. Came back negative.

    Joined:
    Feb 9, 2012
    Messages:
    6,890
    Location:
    Drammen, Norway
    This was discussed in another Model X thread and the conclusion was that true torque vectoring is not possible as long as there is a fixed gear connecting the motor to the two wheels, but you can "mimic" it by breaking on one of the two wheels of the respective motors.
     
  12. snooper77

    snooper77 Member

    Joined:
    Mar 21, 2014
    Messages:
    50
    Why would an SUV/van need torque vectoring in the first place? Not sure I see the benefits.
     
  13. Johan

    Johan Took a TSLA bear test. Came back negative.

    Joined:
    Feb 9, 2012
    Messages:
    6,890
    Location:
    Drammen, Norway
    Agreed - it's mostly for track/performance use. I wouldn't call the X a "van" though, more of a perfomance SUV. It would give better turning performance at high speeds and it could give tighter turn radiuses at low speeds for example. It would probably also make for an even better grip/traction on rain/snow/ice than "only" two-motor electric AWD.
     
  14. Raffy.Roma

    Raffy.Roma Active Member

    Joined:
    Jul 22, 2012
    Messages:
    3,209
    Location:
    Rome (Italy)
    Agree. That's why I think that Torque Vectoring should take place also on the Model X.

    - - - Updated - - -

    For stability reasons in very bad situations (rain, snow, ice and so on). IMO Torque Vectoring is vey useful.
     
  15. snooper77

    snooper77 Member

    Joined:
    Mar 21, 2014
    Messages:
    50
    And how would that be better than the usual ABS + stability control, which also does wheel-specific braking?
     
  16. Raffy.Roma

    Raffy.Roma Active Member

    Joined:
    Jul 22, 2012
    Messages:
    3,209
    Location:
    Rome (Italy)
    Torque Vectoring improves ESC + ABS because not only the brakes are applied at each individual wheel in a completely independent matter but also the torque is applied at each individual wheel in a completely independent matter for the purpose of keeping the wanted path. For this reason I like to call Torque vectoring "active ESC (Electronic Stability Control)".
     
  17. snooper77

    snooper77 Member

    Joined:
    Mar 21, 2014
    Messages:
    50
    That sounds like snake oil to me. Providing a 'basic' torque and then braking individual wheels to reduce the torque on those wheels, which is what stability control does, is equivalent to actively controlling the torque on each wheel. No matter what the approach is, both ESP and torque vectoring lead to different torques on different wheels.
     
  18. Johan

    Johan Took a TSLA bear test. Came back negative.

    Joined:
    Feb 9, 2012
    Messages:
    6,890
    Location:
    Drammen, Norway
    Do you care to elaborate?!? How do you propose to control torque independently to each individual wheel when two wheels are connected to one motor with a fixed gear?!?
     
  19. Raffy.Roma

    Raffy.Roma Active Member

    Joined:
    Jul 22, 2012
    Messages:
    3,209
    Location:
    Rome (Italy)
    I am not an expert of mechanics but I think that for instance Audi in its AWD system is able to apply the torque at each wheel with a differential on the axis of the wheels. Of course this is not compatible with the 2 wheels connected to one motor with a fixed gear.
     
  20. WarpedOne

    WarpedOne Supreme Premier

    Joined:
    Aug 17, 2006
    Messages:
    2,659
    Location:
    Slovenia, Europe
    Those fixed gears include differential that allows left and right wheel to spin at different speeds.
    On an AWD vehicle torque vectoring only differs from ESC system in software i.e. in strategies when it is activated.

    ESC activates brakes only after sensors have detected that vehicle has lost grip.
    Torque vectoring activates brakes "much sooner" i.e. while vehicle still has traction but transversial forces are "big enough".
    Exactly how big is this "big enough" is an optimization problem - make it too small and you waste energy and burn brakes, make it too big and it transforms back into ESC.

    ESC also brakes much harder than torqe vectoring as it only needs to 'relieve' the wheel from drive torque without causing braking torque.
     

Share This Page