Motor Joint Issue

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Motor Joint Issue

Postby MeltingPlastic » Tue Dec 11, 2018 11:05 am

I after updating the SDK a few times I am now seeing some oscillations on a previously working car demo:

https://youtu.be/2kl9dEIq_Es

The wheels are becoming unstable at high speeds (maybe they are just too high?). I know this demo used to work about a month ago.

joint Iteration count is at 4 and joint solve mode settings are at default.
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Re: Motor Joint Issue

Postby Julio Jerez » Tue Dec 11, 2018 12:01 pm

Is not iteration, Iteration do no apply to joints, I was try to make teh joint work with the parallel solver and I probably made a mistake.

no too much work has been done on that area, I thing the best thing is to compare ther changes.
can you find the last version in git hohub that was working, and give me the commit number so that I can compare to teh corrent and see what I made a mistake?
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Re: Motor Joint Issue

Postby Dave Gravel » Tue Dec 11, 2018 5:22 pm

I know it's not the same vehicle implementation but I have test my multibody demo in the new sdk and it seen to work good again.

I have already get similar wheel problem when the damp is not set to zero on the tire body.
If you don't have set it to zero, Maybe you can give it a try.

NewtonBodySetLinearDamping(vBody, 0.0);
NewtonBodySetAngularDamping(vBody, &angdamp[0]);
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Re: Motor Joint Issue

Postby MeltingPlastic » Fri Dec 14, 2018 6:16 pm

The wheel bodies are set to 0 for both angular and linear damping.

I'm still getting this issue with the latest sdk.

Seems like the joints are just weak or something.

I am not using any "Vehicle" classes just regular joints in this demo on purpose. ( I do have another demo that is designed to implement the more serious vehicle classes).
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Re: Motor Joint Issue

Postby Julio Jerez » Fri Dec 14, 2018 6:20 pm

Try the last trick it listed on the last post.
Also even if you are not using any special vehicle, try setting the array as it is in that David demo the I am refactoring.
Basically you can add a global manager to you engine manager, and use the comcept of category or something like that to specify what manager will control you model.
Basically you can think of a model as a collection of bodies and joint working together cooperative.

The idea of simple joints and simple individual bodies
Is to simplistic for anything other than simple passive arrangement.

It will interact with everything in the world.
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