unity – My automobile retains flipping over (or drifting uncontrollably)

I’m experimenting with 3D automobile physics in Unity and desire a good automobile for a racing sport.

I have been attempting to implement turning (and drifting) for this automobile. I would like the automobile to robotically drift at excessive speeds with out the person needing to press an additional key. Nevertheless, it doesn’t matter what I do, the automobile all the time does one in every of two issues when turning: it both flips over when turning at excessive speeds (with out drifting) or spins round uncontrollably till the automobile is going through away from its velocity, i.e. the slip angle is 180 levels. (when drifting).

I’ve checked out these two tutorials (primarily) for assist: https://www.youtube.com/watch?v=CdPYlj5uZeI and https://www.asawicki.information/Mirror/Carpercent20Physicspercent20forpercent20Games/Carpercent20Physicspercent20forpercent20Games.html.

What I would like is a automobile that turns usually at low speeds and drifts at a constant and visual slip angle at excessive speeds. Maybe one thing just like Asphalt 8.

Listed here are some particulars about my automobile’s implementation. (The code is simply too jumbled up to have the ability to present you immediately, however let me know when you want the code)

• I’ve a single Rigidbody and BoxCollider for the automobile. It weighs 1439 kg and is 4 m lengthy x 1 m excessive x 2 m large. The automobile’s high pace is 300 km/h.

• I’m not utilizing WheelColliders. The wheels are simulated and carried out utilizing forces on the rigidbody. Every wheel has its personal GameObject. This GameObject sends a raycast all the way down to the bottom to trace the place the wheel contacts the bottom. If the space is larger than about 1 m, the wheel is registered as not touching the bottom. Every wheel has a script, Wheel.cs, that applies the next forces on the rigidbody at this contact level:

  • Suspension: I take advantage of a suspension pressure of 30000 N/m and a damping pressure of 4000 N/(m/s).

  • Acceleration / Braking: I take advantage of a rear-wheel drive. The pressure utilized on the contact level is a operate of the longitudinal velocity of the automobile and is decided by an AnimationCurve. It begins at 14000 N at resting place, peaks at 21000 N at 120-210 km/h (which I do know is unrealistic due to most traction pressure), and lowers to 15000 N at 300 km/h. The output from this curve is split by the variety of driving (rear) wheels that contact the bottom, and this pressure is solely utilized to the wheels that contact the bottom.

  • Turning / Slide discount: Turning is carried out by lowering or eliminating the lateral velocity of every wheel. The entrance wheels are liable for turning. I take advantage of Ackermann steering if that is related. When the A or D secret is pressed, the wheels flip 12-14 levels relative to the automobile’s course.

    The grip for every wheel determines the fraction of lateral velocity that’s eradicated every physics tick. That is based mostly on an AnimationCurve, and is a operate of the slip angle (it is truly the sine of the slip angle). The grip will get smaller and smaller the extra the wheel strikes sideways.

    I also can multiply the lateral pressure of the rear wheels by some fixed (between 0 and 1) if I believe the pressure is an excessive amount of (drifting implementation). The precise code I take advantage of for that is

    float sidewaysVelocity = Vector3.Dot(rb.GetPointVelocity(hit.level), rework.proper); // Lateral velocity
    float totalVelocity = Vector3.Scale(rb.GetPointVelocity(hit.level), rework.ahead + rework.proper).magnitude; // Whole velocity
    float sidewaysVelocityRatio = totalVelocity == 0 ? 0 : Mathf.Abs(sidewaysVelocity) / totalVelocity; // Discover sideways velocity ratio.
    
    Vector3 lateralAccel = -sidewaysGrip.Consider(Mathf.Clamp01(sidewaysVelocityRatio)) * sidewaysVelocity * rework.proper / Time.fixedDeltaTime; // Acceleration to appropriate the sideways velocity
    bool isDrifting = Vector3.Dot(lateralAccel, rework.proper) > maxLateralForce; // Verify if wheel ought to drift. (I've maxLateralForce set to 14000 N, roughly the automobile's weight)
    
    if(isDrifting && isRearWheel) { // Make the rear wheels drift
        lateralAccel *= Mathf.Lerp(1f, automobile.driftGrip, Mathf.Abs(Enter.GetAxis("Horizontal")));
    } // automobile.driftGrip is about to 0.6 proper now. I've examined values from 0.2 to 0.95.
    
    rb.AddForceAtPosition(lateralAccel, hit.level);
    

  • Rolling resistance: Takes the wheel’s longitudinal pace, multiplies it by a coefficient, and sends a pressure the other method. I’ve used a rolling resistance of 10.5 N/(m/s) for every wheel, so it totals as much as 42 N/(m/s).

• The rigidbody’s COM is about to (0, -0.6, 0).

• Drag can be carried out. It is in the wrong way of the automobile’s velocity and proportional to the sq. of the automobile’s pace. I’ve used a drag coefficient of 1.4 N/((m/s)^2).

The difficulty appears to be within the slide discount: If I flip at excessive speeds (above 80 km/h), the lateral pressure is an excessive amount of and the automobile flips. After I add the drifting code, the automobile spins uncontrollably at excessive speeds. If I apply any type of countersteering (pressure or torque or immediately altering the steering angle, attempting completely different quantities of countersteering, making use of it on completely different wheels), it’s both ineffective or the automobile finally ends up flipping once more. I assumed it made sense to lower the entrance wheels’ grip barely as effectively for drifting, nevertheless it did not work.

What could also be a purpose for this behaviour, and the way can I repair this?

I apologize if there are particulars in regards to the automobile that I ought to’ve supplied, or if I confused you. Additionally, I do know lots of this data is irrelevant, however I added it simply in case.