Car RIG – speed, steering, brakes

[Steve Bentley]

I’m not sure what you are after here. There is no animation (except the motors) and because of the dynamics on everything I assume you are using gravity alone to keep the car on the ground.
Interestingly if you turn the project gravity off it floats off the plane and tumbles. That might be the motor “torque” but I didn’t know it would do that.
I have a feeling the drift you are seeing is the “noise” that is in any dynamics system. Its what keeps the objects moving along and keeps them from running into each other and sticking. So over time that noise could be a butterfly effect that sends the car off course.
Is there a reason to use motors instead of keyframes on the position? Using keyframes would eliminate the noise problem and you might not even need the dynamics. But the dynamics might be the point of it all (exhibiting Newtons laws of motion for instance)

[Jim Scott]

In reference to Steve’s post, in order to stay with a dynamics simulation you could increase the “Steps per Frame” setting under Edit > Project Settings > Dynamics > Expert so that dynamics is calculated more accurately. With the default setting of 5 your car has moved about 175 cm laterally after moving 40,000 cm forward. If you increase the Steps per Frame to 1000 it will have moved less than .2 cm. Not quite “exactly on the same way / direction,” but probably close enough. ????

Edit: You obviously don’t have to crank up the Steps per Frame that far to have a noticeable effect. I was just experimenting out of curiosity. A setting of 100 will give you a lateral deviation of less than 2 cm after 40,000 cm of travel. As higher settings will increase computation times, and thus render times, use them at your discretion.

[Din Iulian silviu]

Thank you !!!

Very helpful.

????

[Steve Bentley]

Hey Jim, How did you do that edit to your post? I’ve always wondered why in a forum such as this I couldn’t fix a boneheaded error of my making (so ya I end up wondering that a lot!)

[Jim Scott]

Hi Steve,

Just click on your post in the main forum listing and that will bring that post up. At the bottom of your post click on “Edit.”

[Steve Bentley]

Ok thanks. I only get that listing of the thread once I’ve clicked on reply, but I do see the edit button now.
Cheers!

[Jim Scott]

I was referring to the main C4D forum listing. I have mine set to “View posts by thread.” If yours is set to “View posts by Topic” it will take that extra step.

[Din Iulian silviu]

I encounter another problem…

If I would to create a keyframe for speed, ( I would like the car to start after a few seconds, I added keyframes for each motor > torque from 0 to 10 ), the car does not start…; if I move the keyframes to start from 150F to 70F it works…, if I move / create a keyframe after the ~120F the car remain blocked…
Where I am wrong?

[Jim Scott]

I can confirm the issue you are seeing, but unfortunately I don’t have any explanation for it or a fix. I have tried keyframing dynamics off and on in the Project settings, as well as doing the same for the motors themselves, but neither of those seem to work. Perhaps someone else has an explanation and/or a fix.