Car Navigation In Unity

Car Navigation In Unity

                                                By Anicia Dcosta, Bharath Bommana, Puja Davande

Logitech G25 Racing wheel

Logitech G25 racing wheel device used to drive a car in video racing games. It is tool for navigation. It includes steering wheel, set of pedals and shift gears. With the help of wheel and pedals user can manage to drive the simulated car.

Racing Wheel

The Racing wheel has following components:

1)Steering Wheel

2)A set of pedals

            Accelerator

            Brake

            Clutch

3)A shifter

            8 buttons

            1 D-pad

            A gear stick.

Car Navigation Tutorial

  

This tutorial will help you to move a car (rover) in the virtual space.  User will be able to move around in the Terrain (space) provided. We are using Logitech G25 racing wheel to move the car. We have created the project in unity and have connected it to G25 racing wheel for the movement.

Creation of the Terrain:

Import the standard Terrain tool from unity and with the help of the tools available we created the below Terrain. This space will be used as a track for the car movement. Create a directional light to light up the terrain.

Figure 1: Terrain

 Car:

 We downloaded the car model from Unity asset store. Search for Vehicle SUV in asset store. Download the car and place it in the terrain.

Figure 2: Car Model

Wheel Colliders:

 This is special collider used for grounded vehicles. With the help of Wheel colliders we can calculate friction and wheel physics. Create an empty game object and name it as Wheel Collider. Create wheel collider under this empty object and assign it to each of the wheels of the car.  Make this object (wheel collider) as a child object of the car object.

Figure 3:Wheel Collider

  
  Car Movement Physics:

We use different methods to make the car moving.

SetupWheelFrictionCurve ():

 This method is called in the start method. In SetupWheelFrictionCurve() we simply create a new WheelFrictionCurve and assign it the values that we think are appropriate for our car. A WheelFrictionCurve is used by Wheel Colliders to describe friction properties of the wheel tire.

Figure 4: SetupWheelFrictionCurve

WheelMovement():

This method is used to take input from the user and apply this to the wheel movement. We are using the input from the vertical as a torque to the rear wheels and horizontal input as the steer angle to the front wheels.

Figure 5: wheelMovement

CarFlipping():

This method is called in Update function . Inside that method we check the rotation of the car. It checks if the rotation is at an angle where the car is not drivable anymore, and if it is, we add the time since the last frame to the resetTimer variable.
If this value eventually adds up to exceed the value that we have set for resetTime (5 seconds by default), we call the method FlipCarBack.
If the rotation of the car is not at a bad angle, we set the timer back to zero instead.

Figure 6: Code for CarFlipping

 

  

FlipCarBack()
:

In FlipCarBack method we get the car back on it’s wheels and sets it’s speed to zero, so we can start driving again from a standstill.

Figure 7:CodeforFlipCarBack

Wheel Rotation:

This method calculates the rotation of each wheel from its wheel collider(rpm) which is applied to the each wheel transform. Below is the code for it.

Figure 8: Code for wheel rotation

 Braking System:

    Car can be stopped using the brake pedal in G25 racing wheel. It uses the braking torque of the wheel collider provided by unity. Below is the code.

Figure 9: Code for braking

Gears: 

Our Idea of gears is little basic. We took the Top Speed of the vehicle as 160 and multiplied it by a factor based on the Joystick button pressed. The factor for first gear is 0.2, second gear is 0.4, third is 0.6, fourth 0.8 and for the fifth gear it is 1.0. That means the vehicle can go at its max speed only in the fifth gear. We used simple if –else if blocks in our code to implement this. We had a hard time to detect the joystick buttons corresponding to each gear, and we were able to find joystick buttons for only first two gears.

Figure 10: Input setting for gears

Figure 11: Gears

                                                                                                

 First Person and Third Person views:

For the First Person view, the camera needs to be set inside the vehicle and should be facing the path in front of the car. For this we position the camera carefully inside the vehicle and adjust the rotations accordingly and make the camera, a child object of the vehicle, so it can move along with the vehicle.

            The third person view, we set it up mainly to show the wheel rotation.  We need to position the camera relative to the vehicle and adjust the rotations to provide a good side-on view from the rear of the vehicle. Also make this camera a child object of vehicle, so it follows the vehicle and provide the third person view.

Figure 12: First person and third person view