Well I'll be :-) I learned to drive a stick and control a slide because of
your vehicle dynamics model ! That game is still #1 in physics in my book.
I'd like to shake your hand sir, fine job :0)
Todd Wasson
---
Performance Simulations
Drag Racing and Top Speed Prediction
Software
http://www.racesimcentral.net/
You lost me :0) I thought my example was a lot easier to follow! lol Maybe
not... :-(
Todd Wasson
---
Performance Simulations
Drag Racing and Top Speed Prediction
Software
http://PerformanceSimulations.Com
From message 2 in this thread:
Downforce coefficient = downforce / (velocity * velocity)
.3 would give massive downforce though. Perhaps you're thinking of aero drag
rather than downforce. (You're using area*Cdf) Don't forget to use velocity^2
instead of velocity, of course.
Message 2 shows how to estimate downforce coefficient if you know the real
operating conditions of the vehicle. For that example, if you wanted to split
the coefficient between the front and rear wings, assign a percentage of (I
think it was .042) to each end. .02 and .022 front/rear, for example.
Yes, another curve would work nicely here. Use an orientation vector and
velocity vector at the wings to calculate the angle of attack, then look up the
downforce. The example in message 2 assumed no changes in angle of attack, so
you'd need to either use the downforce coefficient OR the graph lookup from
angle of attack method, but not both.
Todd Wasson
---
Performance Simulations
Drag Racing and Top Speed Prediction
Software
http://PerformanceSimulations.Com
Yes, this would be fun. I'll try it too when I get a chance (with the Champ
car data from Doug Milliken's book, "Race Car Vehicle Dynamics"). Hopefully,
my triangle intersection calcs will still work upside down.
Todd Wasson
---
Performance Simulations
Drag Racing and Top Speed Prediction
Software
http://PerformanceSimulations.Com
Probably is. Your math is a bit over my head here (wow, gulp!), but I bet
suspension geometry (camber changes with downforce and changing body roll)
could be adjusted to make bad things happen if it was desired. I'm intrigued
by Matt's banked corner thinking on this though. I wonder!
Todd Wasson
---
Performance Simulations
Drag Racing and Top Speed Prediction
Software
http://PerformanceSimulations.Com
>Force available from downforce is :
And...
From the other message about changing camber and roll angle from downforce
stuff, these K1,K2, etc., "constants" won't stay constant, will they? Or are
you simplifying here?
<desperately attempting to remain the world's #1 vehicle dynamics genius in our
solar system, and intimidated by calculus I don't understand :-P>
Todd Wasson
---
Performance Simulations
Drag Racing and Top Speed Prediction
Software
http://PerformanceSimulations.Com
>I should hope so -- we licensed the source for one of our simpler vehicle
>dynamics (physics) models to Atari in the late 1980's and then my good
>friend (from college days) converted/ported the model to run in real-time
>on the game hardware.
I think it's mostly the Americans that say it, strangely enough ;-)
And how on Earth could you get 'real car physics' WITHOUT a math
model! :)
As if a computer can run a tiny racecar on its processor.
Ruud van Gaal, GPL Rank +53.25
Pencil art : http://www.marketgraph.nl/gallery/
Car simulation: http://www.marketgraph.nl/gallery/racer/
...
Ah ofcourse, yes.
That's a lot. I read yesterday that may mainly be due to the wheels
being so open.
Probably, haven't checked for a while. I'm reading Genta's book
currently which also contains a lot of fine data for 5 different types
of vehicles, including the Pacejka constants.
I'll just have to just start with the above formula and see later if I
would include lateral effects (when the air doesn't hit the
vehicle/wing straight on).
I'll go digging for nice wing Cz curves soon. :)
Ruud van Gaal, GPL Rank +53.25
Pencil art : http://www.marketgraph.nl/gallery/
Car simulation: http://www.marketgraph.nl/gallery/racer/
More boring ancient history of Atari Hard Drivin/Race Drivin....<grin>
> How nice! Small world.
> >I'm listed on the credit screen as a "Test Driver" -- I asked to be listed
> >under "Vehicle Dynamics" but Atari management wouldn't allow it...they
> >didn't want the competition to figure out that the game actually used a
> >math model of "real car physics".
Previous games that we know about all used "fake physics" -- for lack of a
better phrase. In earlier games, programming techniques like "growth
motion" were used to simulate speed, there was no concept of inertia or
tire forces, etc. In other words, the game designers and programmers
back then were not aware of vehicle dynamics at all, or even the concept
of using "physics models" as part of the game play.
Hard Drivin' was the first game (that we know of) to combine a 3-d world
database (drive anywhere you want) with a reasonable model of car and
tires. Also included good force feedback with a direct coupled torque
motor (very low time lag) driven by the computed tire forces, yada, yada...
Best Wishes,
-- Doug
I almost lost myself :-)
Eric
Yes, it was a simplification. I had to justify my "simpler" :-)
Well, OK, deuce. We're both number one ... if Doug is OK to be the referee
... :-)
Eric
