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Thread: Car: Torque curve

  1. #1

    Car: Torque curve

    Hi, I've got the following question:

    Has anyone got an idea for cars torque?

    I mean I'd like to do it through a real torque curve.
    But my question is how to do it... (not asking for code but for sketches...).

    I was thinking and came up with this:

    Give the torque curve a formula, I think if I take a look at the graph I think most cars just have a quadratic formula (or maybe a third dimensional).
    So, to create a formula won't be that hard (I don't see problems in this one yet).
    But how to go further?

    I came up with this:

    Every gear has each own curve, which mean its own formula, still no problem.
    But how can I implement the formula?
    Maybe by using RPM?
    How the car accelerates is defined by the acceleration of rpm (correct me if I'm wrong).

    By using the the formula I can say x = rpm.
    y = acceleration speed.

    And then there is the speed down (by releasing the driving button) this acceleration will be defined by a "- constantnumber * weightofthecar and some other car-related code".
    The acceleration (or should I say de-acceleration) of the rpm will be something like:
    Torquecurve * "- constantnumber * weightofthecar and some other car-related code.
    So that when someone releases the driving button and pushing it again, the rpm will decrease and then increase.
    And because rpm = x I can find the y = acceleration whenever I want...

    My question is, will this be a good way to do this?
    Is it reliable?

    Or does anyone have any other ideas?
    Ideas are always welcome,

    Thanks in advance.

    Angelo.
    "What we cannot speak about we must pass over in silence."

  2. #2

    Car: Torque curve

    Try reading this: Linky

    I think that one explains releations pretty well
    Peregrinus, expectavi pedes meos in cymbalis
    Nullus norvegicorum sole urinat

  3. #3

    Car: Torque curve

    A quick suggestion. If you want to model car physics the 8th chapter of Physics for Game Programmers (ISBN: 159059472X) is absolutely chok of helpful information for you. And nowadays it's pretty cheap too.

    However, here are some helpful formulae for you:

    There is a minimum Torque[Engine] value per car, and it does tend to have a maximu too. The minimum is all you should concern yourself over.

    Code:
    Torque[Engine] = Torque[Engine]*RPM;  // RPM is really the engine turnover rate, what we call revolutions per minute.
    
    Ang_Vel = (2 * Pi * RPM) / 60; // This is the actual angular velocity in rad/s.
    
    Power[Engine] = Torque[Engine] * Ang_Vel;
    
    // Now we get into gears and the transmission...
    
    Torque[Wheels] = Torque[Engine] * Gear_Ratio[Current] * Gear_Ratio[Max];
    That's about all I can give with my understanding. I'm sorry that I can't help you much more, but that's some of the basics for you.

  4. #4

    Car: Torque curve

    Thanks for the replies.

    I think I was at the right direction... I know how it works within the car and the physics but I'm not sure how to implement it into a game engine.
    But I'll experiment with it...

    *BTW: Why don't I create an automatic gearbox, its much easier then with those gears!!!*

    Enough moaning, I'll fix it (within a year or two...)
    "What we cannot speak about we must pass over in silence."

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