Drive - Vehicle Dynamics Demo

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Drive - Vehicle Dynamics Demo

Postby PierreBlanc » Tue Sep 18, 2007 8:12 pm

Hi,


I'm working on a vehicle simulation framework since quite few time already, and I just finished a small demo which shows it in action.

I'm simulating the vehicles using a ray cast car method.

There are 3 cars available in the demo each with several configurations and 3 tracks.

Version 0.2.3 available with new configuration files and few fixes, see changelog.txt


You can download the demo using the following link : Drive - Vehicle Dynamics Demo 0.2.3

Everything is explained in the README.txt file.


Here are few screenshots :

Image

Image

Image


Your comments are welcome ! ( only about physics ^^ )
Last edited by PierreBlanc on Mon Sep 24, 2007 4:24 pm, edited 3 times in total.
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Postby Julio Jerez » Wed Sep 19, 2007 8:38 am

wow very, very nice, tire threads and evrything. this is ray cast car?
could you tell a litle about your technique, it sure look and feel nice to drive.
also how do you get those nice models, are they public?
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Postby PierreBlanc » Wed Sep 19, 2007 10:52 am

Yes this is a ray cast car !


The vehicles models are free to use, I downloaded them from various sources, at least free to use for non-commercial projects.
You can find the different links inside the credits/ directory.


To get an overview about the vehicle parameters, the best is to open the configuration files which are located inside the vehicles/ directory ( .xml files ).

Basically, absolutly no cheat is used like applying additional torque etc... The only thing is that the center of gravity is maybe a bit lower than in real life, but it could be higher it's just to make it easier to drive without a racing wheel and analog pedals, which i haven't plugged into the demo.

The tire model in the demo is a Pacejka like, but I also use a custom tire model for asphalt driving and another one in development for driving into every kind of ground surface where you can sink into. That will not be ready before a while !

The whole model is not yet complete, I'm currently working on LSD and locking differentials with locking arrays, and a component based system with an editor to build anything which has wheels. Additionnaly, there is a lot of work remaining for modeling different kind of suspensions, a better engine modeling, aerodynamic, etc... a lot !

NewtonDynamics wise, the technique is quite simple, some rays are fired from the suspensions in their direction. I made a custom joint to apply suspension constraints and tire lateral and longitudinal constraints. I use forces for gravity effect ( vehicle, fuel tank, etc.. ) and aerodynamic drag. A treecollision for the ground, with different ground surfaces per polygon.


Well it's hard to explain in details what I have done, but I'm ready to answer any specific questions if I can.


What I can do is give links to reference materials I have been using :

Brian Beckman's Physics of Racing
[url=http://www.amazon.com/Tire-Vehicle-Dynamics-Hans-Pacejka/dp/0768017025/ref=pd_bbs_sr_1/102-7954284-5210553?ie=UTF8&s=books&qid=1190212643&sr=8-1]
Tire and Vehicle Dynamics, 2nd edition by Hans B Pacejka[/url]


Newton again has been really easy to use, and very stable which is a big pro for this kind of simulation. However, what about soft bodies, particle physics, is it a planned feature for 1.6 and is there a planned date about it ? I know it's free, I know it will be ready when it will :) I'm just asking since i'm curious about how the development is going.

And don't take me wrong, we are all busy with a lot of things so I any answer will be ok !
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Postby Julio Jerez » Wed Sep 19, 2007 11:52 am

PierreBlanc wrote:Newton again has been really easy to use, and very stable which is a big pro for this kind of simulation. However, what about soft bodies, particle physics, is it a planned feature for 1.6 and is there a planned date about it ? I know it's free, I know it will be ready when it will :) I'm just asking since i'm curious about how the development is going.
And don't take me wrong, we are all busy with a lot of things so I any answer will be ok !

We are testing alpha already, and working on some features.
I do not want to post date, because it put too much pleasure on me but it is sooner than you think.

So you are using a custom joint, I see. Anyway the driving feel very nice.
I want to add a basic rig for setting ray car like that, not a working car because that not what newton is all about, but a basic framework for building with suspension torque, tire model, so that the user would build on top of that.
The joint car rig in the current version is too slow for games.
Please keep me post with you progress, your approach is very interesting.
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Postby Julio Jerez » Wed Sep 19, 2007 11:53 am

PierreBlanc wrote:Newton again has been really easy to use, and very stable which is a big pro for this kind of simulation. However, what about soft bodies, particle physics, is it a planned feature for 1.6 and is there a planned date about it ? I know it's free, I know it will be ready when it will :) I'm just asking since i'm curious about how the development is going.
And don't take me wrong, we are all busy with a lot of things so I any answer will be ok !

We are testing alpha already, and working on some features.
I do not want to post date, because it put too much pleasure on me but it is sooner than you think.

So you are using a custom joint, I see. Anyway the driving feel very nice.
I want to add a basic rig for setting ray car like that, not a working car because that not what newton is all about, but a basic framework for building with suspension torque, tire model, so that the user would build on top of that.
The joint car rig in the current version is too slow for games.
Please keep me post with you progress, your approach is very interesting.
Julio Jerez
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Postby Julio Jerez » Wed Sep 19, 2007 1:20 pm

wow I tryed some more model, the mozzle car is very cool to drive.
I see that you also have many tracks, are thsoe also public,
if so can you point me to a link.
I will put this demo in teh link for peopel to see it.
Really I am extreemtly impresed, I tip my had to you darth master.
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Postby PierreBlanc » Wed Sep 19, 2007 2:27 pm

Thanks for the nice comments, it's great to have feedback !

The tracks and their textures are made by me, as long as you credit me I have no problem if someone wants to use them as long as it's in a non-commercial project but I doubt that could be the case :)
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Postby Sury » Wed Sep 19, 2007 3:52 pm

Very, nice. Maybe the grip to the ground should be a bit harder, so vehicles wont slide as much on turns, but that's probably a question of setup.

BTW, do you know where i can get some free Renault models ? My car is a R19 and as i'm familiar with those cars I need them for a simulation/diagnostic application i'm developing.
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Postby Dave Gravel » Wed Sep 19, 2007 4:01 pm

Very nice, I like it.
The grip looking good too on the asphalt, just the cross rally looking to need a little bit more grip but it is very good anyway.

Good work.
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Postby PierreBlanc » Wed Sep 19, 2007 6:06 pm

I have thrown in the configuration files a bit quickly, I will take the time later this week end to tweak them, I agree the grip need to be raised a bit, both on asphalt and dirt.

I found that about R19, but it's not free : http://www.turbosquid.com/FullPreview/I ... /ID/228519
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