Question by SputnlK · Feb 25, 2015 at 05:53 AM · physics raycast vehicle wheel sideways

How do i make my Raycast Car not slip at all?

hey,

im trying to make a car with a rigidbody and rays for each wheel.

the car gets vertical forces that are equal to a spring and a damper in real life and they work pretty good so far.

forward movement is pretty simple for now but it works too. the problem is the sideways force. i cant figure out how to add the right force to make the wheels not slip at all.

thats why im asking you to help me. i appreciate every bit of help.

this is what i use to calculate the force that works against the x motion. (dont mind the if's)

 xForce = localHitVel.x;
 
 if (xForce < 0)
 {
 
     body.AddForceAtPosition(transform.right * (xForce - xForceAdd), transform.position, ForceMode.VelocityChange);
 
 }
 if (xForce > 0)
 {
 
     body.AddForceAtPosition(transform.right * (xForce + xForceAdd), transform.position, ForceMode.VelocityChange);
 
 }

alt text

EDIT:

Fixed it... i applied the "Magic Formula" by Pajecka

http://en.wikipedia.org/wiki/Hans_B._Pacejka

http://www.racer.nl/reference/pacejka.htm

xforce.jpg (36.7 kB)

Add comment · Show 2

APProjects · Aug 09, 2015 at 02:14 PM 0

Hi!

I wonder about your implementation. Did you write a custom suspension script with forces or you're relying on fixed colliders for "suspension" so the wheels don't fall through the road mesh?

How does it work for steering?

ViFFeX360 · Mar 10, 2016 at 01:52 AM 0

Could you perhaps share how you managed to apply Pacejka forces?

I am really struggling to find a good source of info on it, and every project I've seen so far has done it in a very convoluted way to "simulate" a car, whereas I rather would like a simple implementation that's more like an arcade racer that behaves semi-realistically.

I understand the Pacejka formula itself. I also understand suspension physics, I have made a car that has realistic suspension as well. It even has weight transfer when I hit the acceleration/brakes.

But steering/cornering and sideways force baffle me, I can't seem to wrap my head around it. Considering you managed to find out how to apply it it would be really helpful if you could share the basics :)

Thanks!

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How do i make my Raycast Car not slip at all?

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