Unity Wheel Collider for Motor vehicle Tutorial 2018

Unity Wheel Collider for Motor vehicle Tutorial 2018


The main aim of this mail is to give an mind of how to work with wheel collider and physics of Wheel Collider .

Want to Make a Car Racing Game?

Having troubles with Car Physics?
Where to use Wheel Collider?
How to use Wheel Collider?
What are the components of Wheel Collider?
How is Wheel Collider Different than other Colliders?
Have these Questions in Your Mind?
No worries. You ‘ll know everything about Wheelcollider after reading this post .
Wheel Collider is a special kind of Collider which is used for vehicles. It has in built collision detection technique and physics of actual Wheel .
It can be used for objects other than wheels ( like bumper Boats, bumper cars etc which uses suspension force ), but it is particularly designed for vehicles with wheels .
Is there is anything special which is not in other Colliders?
Yes, each and every collider has something special ( That ’ s why Unity created them ) .
In this Collider, you will get all the components which are used to make vehicle drivable. You will get to know most of the components hera .
To get a car working in Unity it ’ randomness useful to understand how the Wheel Collider part works internally. here we attempt to explain that in just a few minutes .
This is how you look at your dash and glazed car .
Actual World Car
But, Unity doesn ’ t have good eyesight. So one looks at your cable car like this .
Car as per Unity
4 wheels colliders and 1 car collider, that ’ s it !
nowadays Let ’ s Discover inside Wheel Collider .
wheel Collider toolbox
Components of unity toolbox
Wheel doesn ’ thyroxine have any supreme headquarters allied powers europe it is Raycast based .
Mass & Radius: multitude and radius of the wheel. ( easy international relations and security network ’ thyroxine it ? )
Below I had given a little initiation about physics of wheel collider .
Physics of wheel collider
Every steering wheel counts it ’ s form mass. Sprung batch ( not weight ) is used to apply individual military unit on each wheel .
suspension Distance is the distance between soap droop and soap compression. This suspension is calculated based on rest pose .

Suspension Force(F) = (sprungMass * g ) +( jounce * stiffness) - (damper * jounceSpeed)

offset of the wheel relative to the rest pose.

that means physics friction. (setting this to 0 means no friction change this runtime to simulate in various ground material).

damping value applied to the wheel

wheel moved with suspension travel direction.

Tire simulation rather than using active or electrostatic material slip-based material is used .
To learn more about physics of rack collider pawl hera

first we need to setup Scene for that ( Don ’ triiodothyronine Worry that is Easy partially ) .
Step 1: Create a 3D plane Object give it scale of ( 100, 0, 100 ) .
Step 2: Create an empty Object add Rigidbody 3D. diagnose it as “ Car ”
Step 3: Import 3D Car Model inside your Scene ( you will get download link below ) add as a child of Car .
Step 4: Take engagement Collider and add as a child of Car name it ” CarCollider ” .
Step 5: Create Two empty GameObject inside Car name them as “ Wheel Meshed ” and “ Wheel Collider ” .
Step 6: Inside Wheel Meshes add 4 empty GameObject name them as “ FL ”, ” FR ”, ” RL ” and “ RR ”. assign Mesh of Wheel ( you will get download link below ). Set their position .
Step 7: Inside Wheel Collider add 4 empty GameObjects name them as “ Col_FL ”, ” Col_FR ”, ” Col_RL ” and “ Col_RR ”. Add bicycle collider as their component. Set radius of colliders lapp as the size of mesh and set their stead same as the interlock have .
wheel collider Scene
Yeap, Its make ! actually that was the Difficult separate to setup scene .
now Time for actually easy separate Scripting .
PART-2: SCRIPTING (Check Script Reference Click here)

public class AxleInfo
	public WheelCollider leftWheelCollider;
	public WheelCollider rightWheelCollider;
	public GameObject leftWheelMesh;
	public GameObject rightWheelMesh;
	public bool motor;
	public bool steering;

In this AxleInfo class, we are going to store information for a pair of the roulette wheel .

Variable Name
Variable Type

leftWheelCollider / rightWheelCollider
To drive a car using WheelColliders inbuilt physics.

leftWheelMesh / rightWheelMesh
To Visualize rotation and movement of wheels.

Enable movement of this pair of wheels.

Enable rotation of this pair of wheels.

immediately, We are going to drive car

public class CarDriver : MonoBehaviour
	public List axleInfos;
	public float maxMotorTorque;
	public float maxSteeringAngle;
	public float brakeTorque;
	public float decelerationForce;

	public void ApplyLocalPositionToVisuals (AxleInfo axleInfo)
		Vector3 position;
		Quaternion rotation;
		axleInfo.leftWheelCollider.GetWorldPose (out position, out rotation);
		axleInfo.leftWheelMesh.transform.position = position;
		axleInfo.leftWheelMesh.transform.rotation = rotation;
		axleInfo.rightWheelCollider.GetWorldPose (out position, out rotation);
		axleInfo.rightWheelMesh.transform.position = position;
		axleInfo.rightWheelMesh.transform.rotation = rotation;

	void FixedUpdate ()
		float motor = maxMotorTorque * Input.GetAxis ("Vertical");
		float steering = maxSteeringAngle * Input.GetAxis ("Horizontal");
		for (int i = 0; i < axleInfos.Count; i++)
			if (axleInfos [i].steering)
				Steering (axleInfos [i], steering);
			if (axleInfos [i].motor)
				Acceleration (axleInfos [i], motor);
			if (Input.GetKey (KeyCode.Space))
				Brake (axleInfos [i]);
			ApplyLocalPositionToVisuals (axleInfos [i]);

	private void Acceleration (AxleInfo axleInfo, float motor)
		if (motor != 0f)
			axleInfo.leftWheelCollider.brakeTorque = 0;
			axleInfo.rightWheelCollider.brakeTorque = 0;
			axleInfo.leftWheelCollider.motorTorque = motor;
			axleInfo.rightWheelCollider.motorTorque = motor;
		} else
			Deceleration (axleInfo);

	private void Deceleration (AxleInfo axleInfo)
		axleInfo.leftWheelCollider.brakeTorque = decelerationForce;
		axleInfo.rightWheelCollider.brakeTorque = decelerationForce;

	private void Steering (AxleInfo axleInfo, float steering)
		axleInfo.leftWheelCollider.steerAngle = steering;
		axleInfo.rightWheelCollider.steerAngle = steering;

	private void Brake (AxleInfo axleInfo)
		axleInfo.leftWheelCollider.brakeTorque = brakeTorque;
		axleInfo.rightWheelCollider.brakeTorque = brakeTorque;

This script was a little act unmanageable but I am here to help you .

Variable Name
Variable Type

List of AxleInfo Which contains a pair of wheels data.

maximum Torque is applicable on Vehicle.

Maximum angle at which wheel is rotate.

Torque is applied when a brake is pressed.

This force is applied to stop the vehicle because of friction.

ApplyLocalPositionToVisuals (AxleInfo axleInfo)

  • This Method takes one argument: axleInfo. This method is used to Display rotation and position of WheelMeshes.


  • This is Unity callBack used to do certain changes in physics at fixed time.
  • Inside that, we will take Input.
  • Vertical: W/Up Arrow for Forward & S/Down Arrow for Backward.
  • Horizontal: A/Left Arrow for Left Side Rotation. & D/Right Arrow for Right Side Rotation.
  • Space: To Stop(brake).
  • Assign this Script to our “Car” GameObject.
  • Add Size of AxleInfo to 2.
  • Now add your Colliders and Meshes to appropriate Location.
  • We have 3 methods to Control Car Acceleration(), Steering() and Brake().

You can relate all the methods listed below. These methods are works like how actually Vehicle we drive in reality Accelerator, Brake ( No Clutch hera ). Acceleration()

  • It is used to make the vehicle move forward and backward.
  • If forward or backward buttons are not clicked then need to add Deceleration().
  • motorTorque is used to add torque (In forward or backward direction) in a vehicle.
  • When the vehicle is moving at that time brakeTorque is needed to change to 0.


  • It is used to stop the vehicle when forward and backward buttons are not pressed.


  • It is used to turn angle of vehicle.
  • steerAngle is used to change an angle of the the vehicle


  • It is used to stop the vehicle using brakeTorque property.

PART-3: ASSIGNING VALUES ultimately at the end This the last thing to make your car drivable. enable motive if you want to Apply Force and Suspension on That Wheel .
enable Steering if you want to give rotation Force on that Wheel. Maximum Motor Torque change as per your car ’ sulfur Rigidbody mass .
utmost Steering Angle must be between ( 30-35 ). Brake Torque depends on how much Brake Torque you want to apply .
Deceleration Force is must be less than Brake Torque .


experiment with This Value to make your Car function smoothly.


Brake Torque and Deceleration Force value motivation to be much higher to stop normally ( 1e+5 to 1e+8 ) .
Feel complimentary to contact us if you in truth liked this web log. And preceptor ’ thymine forget to share your comments below !

reference : https://tonupboys.com
Category : Car Brakes