Sign in to follow this  
Lyve

Realistic acceleration and turning of a car

Recommended Posts

Lyve    116
Hello members, I know that most tutorials teach you how to turn your car that way: Find the intersection point where a front wheel intersects with the rear wheel and rotate about that point. However, because real cars are not "rotated about a point" I want to try a different approach: On a front driven car the front wheels apply a force to the car's body, trying to move them into the direction where the wheels are pointing to. However, the rear wheels don't allow that because of friction with the ground. Is it possible to calculate the correct rotation of the car for a timestep by developing a formula that uses the above criteria? Would it be a "good" solution, or would you prefer to use the common one? I think about using this approach because nothing is faked here, and maybe it's better for further development.

Share this post


Link to post
Share on other sites
Motorherp    613
If you want very realistic racing physics you're going down a long a complicated road. Especially the tyre physics stuff. Check out this web site for some help getting you started.

Share this post


Link to post
Share on other sites
CombatWombat    673
It's not too terribly complicated, there are just alot of little details that will need to be worked out along the way.

Basically, you need two things from all of your tires, and from them you can derive the force they put on the body.

1) SlipRatio - this is a ratio of how much faster the edge of the tire is moving (linearly) with respect to the ground.

the problems with slipRatio: you cannot use the direct formula as it becomes void when the cars speed approaches zero. There are workarounds to this involving differential equations and the like.

2) SlipAngle - angle between the wheels facing direction, and velocity direction.

The problems with slipAngle: not too much, just need to make sure your signs are correct and there is some way to differentiate between left/right slipping.

So from that, you can get as basic or complicated as you want. You could make a linear increase of sideways force with slipAngle, or you could go all out and use a Pacerjka type equation.

Further complication will arrise if this is 3d, as you must then deal with suspension (springs/dampers/getting the force between road and tire, etc) and the fact that most tire models do not take into account parking on hills and such. If you are parked and your tires are not moving, then slipRatio is zero, and force is zero. So your car slides down the hill.

For this and more...
http://home.planet.nl/~monstrous/tutcar.html

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

Sign in to follow this