自定义车轮碰撞器前进正常但转向行为异常的问题求助

各位大佬好，我正在自己实现一个自定义的车轮碰撞器，目前前进的逻辑已经跑通了，但转向的表现完全不对劲——有时候转向还算正常，但一旦同时给油门，车轮就会反向打滑甚至原地转圈，完全不符合预期。我知道现在的车轮模型还很基础，想先把前进和基础转向的逻辑调对再做后续优化，麻烦帮忙看看问题出在哪？

我的实现代码 #

CustomWheel.cs

public CarController car;

[Header("Wheel Parameters")]
public float radius = 0.35f;
public float grip = 1f;
public float outputForce;
public bool showStats = false;

[Header("Steering & Alignment")]
public bool isSteerable = false;
public float maxSteeringAngle = 30f;

[Header("References")]
public Transform wheelVisual;
public bool showDebug = true;

private float steeringAngle;
[HideInInspector] public Vector3 wheelForward { get; private set; }

public override void Simulate(float dt)
{
    outputForce = torque / radius;

    // Geometry
    steeringAngle = isSteerable ? car.steerInput * maxSteeringAngle : 0f;
    Quaternion steerRot = Quaternion.Euler(0f, steeringAngle, 0f);

    // Calculate effective orientation
    Quaternion combinedRotation = steerRot;
    wheelForward = combinedRotation * transform.forward;
    Vector3 wheelRight = combinedRotation * transform.right;

    // Calculate wheel linear speed
    float wheelLinearSpeed = angularVelocity * radius;
    if (showStats) Debug.Log($"Wheel Linear Speed: {wheelLinearSpeed}");

    float forwardVelocity = Vector3.Dot(car.carRb.linearVelocity, transform.forward);
    if (showStats) Debug.Log($"Forward Velocity: {forwardVelocity}");

    // Calculate simple slip ratio
    float slipRatio = (wheelLinearSpeed - forwardVelocity) / Mathf.Max(Mathf.Abs(forwardVelocity), 1f);
    slipRatio = Mathf.Clamp(slipRatio, -1f, 1f);
    if (showStats) Debug.Log($"Slip Ratio: {slipRatio}");

    // Linear traction model
    outputForce = slipRatio * grip * 100f; // Scale for force realism
    if (Mathf.Abs(outputForce) < 0.001f) outputForce = 0f;

    // Resistance torque from ground force
    float resistingTorque = outputForce * radius;
    if (showStats) Debug.Log($"Resisting Torque: {resistingTorque}");

    // Apply net torque
    float netTorque = torque - resistingTorque;
    if (showStats) Debug.Log($"Net Torque: {netTorque}");

    // Integrate angular acceleration
    UpdateAngularVelocityFromTorque(netTorque, dt);

    // Apply forces
    //Vector3 force = wheelForward * outputForce;
    //car.carRb.AddForceAtPosition(force, transform.position);

    // Visual
    UpdateVisual();

    // Debug
}

private void UpdateVisual()
{
    if (wheelVisual != null)
    {
        //wheelVisual.position = for suspension work
        wheelVisual.Rotate(Vector3.right, angularVelocity * Mathf.Rad2Deg * Time.fixedDeltaTime);
        Vector3 angles = wheelVisual.localEulerAngles;
        wheelVisual.localEulerAngles = new Vector3(0f, steeringAngle, 0f);
    }
}

CarChassis.cs

public CarController car;
public List<CustomWheel> wheels = new();

void FixedUpdate()
{
    float dt = Time.fixedDeltaTime;
    //Vector3 totalForce = Vector3.zero;
    foreach (var wheel in wheels)
    {
        wheel.Simulate(dt);
        Vector3 force = wheel.wheelForward * wheel.outputForce;
        car.carRb.AddForceAtPosition(force, wheel.transform.position); // Apply force from each wheel to the car Rigidbody
        //totalForce += wheel.wheelForward * wheel.outputForce;
        //car.carRb.AddForceAtPosition(force, wheel.transform.position);
        //Debug.Log("Applying Force");
    }
    //car.carRb.AddForce(totalForce);
}

我自己排查的可能问题点 #

1. 滑移率计算的方向不匹配：现在用transform.forward来计算车身的前进速度，但转向后车轮的实际前进方向是wheelForward，这会导致滑移率计算错误，牵引力方向和车轮朝向脱节，一给油门就打滑。
2. 缺少侧向抓地力逻辑：当前只处理了纵向（前进/后退）的滑移和牵引力，完全没考虑转向时的侧向滑移，没有侧向抓地力的话，车轮根本没法跟着转向方向走，只会在纵向打滑。
3. 车轮与车身速度的相对关系计算不准：现在用的是车身质心的速度，而且没结合转向后的车轮方向，导致滑移率的偏差很大，牵引力的输出完全不对。
4. 视觉更新逻辑有bug：UpdateVisual里先Rotate模拟滚动，然后直接设置localEulerAngles，把滚动的角度覆盖了，不过这个应该只是显示问题，不是物理的核心问题。

我尝试想到的修改方向 #

1. 修正滑移率的计算方向

把计算forwardVelocity的代码改成用wheelForward，让滑移率匹配转向后的车轮朝向：

float forwardVelocity = Vector3.Dot(car.carRb.linearVelocity, wheelForward);

2. 添加侧向抓地力的计算

在CustomWheel的Simulate方法里，加入侧向滑移的计算和侧向力：

// 计算侧向滑移速度
float sidewaysVelocity = Vector3.Dot(car.carRb.linearVelocity, wheelRight);
// 简单的侧向滑移角（可根据实际效果调整计算方式）
float slipAngle = Mathf.Atan2(sidewaysVelocity, Mathf.Abs(forwardVelocity)) * Mathf.Rad2Deg;
// 侧向抓地力，与滑移角成比例，用grip参数控制强度
float lateralForce = -slipAngle * grip * 10f; // 系数可根据实际效果微调

然后在CarChassis里应用力时，同时加上纵向和侧向的力：

// 需要在CustomWheel中暴露wheelRight和lateralForce，或者直接在Simulate中计算总力
Vector3 totalForce = wheel.wheelForward * wheel.outputForce + wheel.wheelRight * lateralForce;
car.carRb.AddForceAtPosition(totalForce, wheel.transform.position);

3. 修正车轮与车身速度的计算逻辑

改用车轮位置的实际速度（而非车身质心速度）来计算滑移率，结果会更准确：

// 计算车轮位置的车身实时速度
Vector3 wheelPositionVelocity = car.carRb.GetPointVelocity(transform.position);
// 纵向速度为车轮位置速度在wheelForward上的投影
float forwardVelocity = Vector3.Dot(wheelPositionVelocity, wheelForward);
// 车轮的预期线速度矢量
Vector3 wheelDesiredVelocity = wheelForward * angularVelocity * radius;
// 纵向滑移速度
float longitudinalSlip = Vector3.Dot(wheelDesiredVelocity - wheelPositionVelocity, wheelForward);
// 修正后的滑移率
float slipRatio = longitudinalSlip / Mathf.Max(Mathf.Abs(forwardVelocity), 1f);
slipRatio = Mathf.Clamp(slipRatio, -1f, 1f);

4. 修复视觉更新的逻辑

调整UpdateVisual，避免覆盖车轮滚动的角度：

private void UpdateVisual()
{
    if (wheelVisual != null)
    {
        // 计算本次帧的滚动角度增量
        float rollDelta = angularVelocity * Mathf.Rad2Deg * Time.fixedDeltaTime;
        // 保留当前的滚动角度，仅更新转向角度
        float currentRoll = wheelVisual.localEulerAngles.x;
        wheelVisual.localEulerAngles = new Vector3(currentRoll + rollDelta, steeringAngle, 0f);
    }
}

有没有大佬能帮我看看这些思路对不对，或者还有其他我没考虑到的问题吗？

内容来源于stack exchange