Raycast Steering problems

Physics
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1

Hi all

I’m very new to unity and have been playing with a prototype to try and get a car moving around in 3d. Ive gotten some suspension working based on a rigidbody with 4 raycasts for the wheels, but im getting in a muddle with the steering side of things

I have an Empty GameObject with a RigidBody component attached, lets call that CarPrototype. It contains a simple cuboid to represent the car itself. The CarPrototype has a script that handles input from controller

this.steering = maxSteeringAngle * (controls.Gameplay.SteerRight.ReadValue<float>() - controls.Gameplay.SteerLeft.ReadValue<float>());

wheelFR.transform.eulerAngles = new Vector3(0, this.steering, 0);
wheelFL.transform.eulerAngles = new Vector3(0, this.steering, 0);

The CarPrototype has 4 Empty GameObjects that i use for raycasting for suspension and am trying to use for steering. The specific steering part of the script attached to these “Wheel” objects is as follows

/**
            * Steering
             *
             */
          
            // world space velocity of this tire...
            Vector3 tireWorldVel = rb.GetPointVelocity(transform.position);
           Vector3 steeringDir = transform.right;
            Debug.Log(transform.position);
            float steeringVel = Vector3.Dot(steeringDir, tireWorldVel);
            Debug.Log("Steering Vel = " + Math.Round(steeringVel,2));
            float desiredVelChange = - steeringVel * tyreGripFactor;
            float desiredAccel = desiredVelChange / Time.fixedDeltaTime;
            rb.AddForceAtPosition(steeringDir * tyreMass * desiredAccel, transform.position);

What seems to happen is that the car steers to the maxSteeringAngle in degrees from the z axis, but then wont steer any further. If i release the controller, the car automatically steers back to point along the z axis. Its almost like the velocity that im trying to add force against is not calculated correctly. Can anyone help point me in the right direction (literally :smile:)

Thanks

2

You may find this video very useful to design and implement your car controller:

3

That is what i’ve based things on, but as the code is shown out of context of the whole codebase, Im having issues. I understand the theory behind it but i think theres just a bug in my own code that i cant work out. I’ll keep at it, thanks.