strong impulses when actuating joints

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strong impulses when actuating joints

Postby blackbird_dream » Thu Oct 04, 2018 5:20 am

Hi,
I observed severe impulses (force pulses) when actuating sliders.
For example here, see the mast vibrating when lifting the heavy load.
https://youtu.be/ctcU4b1Yc70
When shifting the load left and right the pulses produces wheel drifting laterally.
I've no test for the moment, sorry.
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Re: strong impulses when actuating joints

Postby MeltingPlastic » Thu Oct 04, 2018 7:12 pm

This could be because of the tol variable what was inside the actuator joints. commit: b37b3f50564a065b3935d6d4f9352c823e276a7e might have fixed this issue (9/29/2018). Not sure if that has been merged into the Unity plugin yet.
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Re: strong impulses when actuating joints

Postby Julio Jerez » Thu Oct 04, 2018 8:35 pm

yes is was merge, and I was wondering the same thing. Was it working before blackbird?
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Re: strong impulses when actuating joints

Postby blackbird_dream » Fri Oct 05, 2018 7:43 am

oh well, magnificent !
I was still with ad2c9b489d7b25b0a51fb5c7bba3b90507a25180 dated 9/4
I'll test it.
Yes it worked fine with v1.5.3 ancient time.
Thks
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Re: strong impulses when actuating joints

Postby Julio Jerez » Fri Oct 05, 2018 9:18 am

oh so you have a version before the fix submitted by Melting Plastic,
try to update the newton SDK and see how that goes.

I am still dubious if the fix has an inherited jitter or not, but the test show it does not.

anyway try getting the late SDK, Melting Plastic has submitted a lots of bug fixes.
and if still jitters, I will check it out over the weekend.
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Re: strong impulses when actuating joints

Postby blackbird_dream » Fri Oct 05, 2018 10:36 am

it seems to be worse indeed.
The whole truck can't stop jittering.
I'll send you the case study by PM
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Re: strong impulses when actuating joints

Postby Julio Jerez » Fri Oct 05, 2018 10:42 am

so it is broken with newer build?

I suspected the change was not enough, I just could not test because my test does not has the high mass ratio. but the way is was is also wrong.

I believe I know what it is, this is solved for other joints, but I never added the fix to the actuators because I thought they would not need it.

anyway send me the test when you can, I will fix it tomorrow.
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Re: strong impulses when actuating joints

Postby blackbird_dream » Fri Oct 05, 2018 10:52 am

I've sent it.
It's difficult to know what is wrong, I mean what is the cause of the jitter.
Is the joint or the contact between the load and the fork ?
What I know is that with the previous version I was able to keep the truck's wheels at rest and now I can't due to the jitter.
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Re: strong impulses when actuating joints

Postby blackbird_dream » Fri Oct 05, 2018 11:21 am

here is a video of the load on the fork with constant elevation :
https://youtu.be/dxYZiBlwFDY
the truck can't stop jittering.
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Re: strong impulses when actuating joints

Postby Julio Jerez » Fri Oct 05, 2018 12:33 pm

is not on your side, the original joint had a dead zone and we tried to eliminate it, but the fix is not quite right because it does the correction after the target was reach which cause the actuator speed chance direction.
it is my fault, I will fix it as soon as I can.
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Re: strong impulses when actuating joints

Postby Dave Gravel » Fri Oct 05, 2018 12:36 pm

Hi Blackbird, do you use solver 0 for your joints ?
You search a nice physics solution, if you can read this message you're at the good place :wink:
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Re: strong impulses when actuating joints

Postby blackbird_dream » Mon Oct 08, 2018 2:31 am

dunno Dave.
Thks Julio. Looking forward to a new build
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Re: strong impulses when actuating joints

Postby Dave Gravel » Mon Oct 08, 2018 3:14 am

I say this because normally solver 0 on joint give more precision and 1, 2 less if i'm not wrong.
I don't talk about the world solver but really about the joint.Solver.
I remember that you have already change the solver for test about the bounce problem.
With your simulation type you surely need the solver 0 on all joints.
You use the unity plugin, maybe by updating it or by error a solver setting have change on the joints.

Sorry if it have no relation at all.
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Re: strong impulses when actuating joints

Postby blackbird_dream » Mon Oct 08, 2018 4:09 am

Yes I remember.
I changed it in the sources but it did'nt solve the problem of wrong bouncing AFAIR. If there is an issue about the joint managment itself, I understood dealing with a dead zone, I'd prefer to wait for an improvment rather than 'fiddling about'
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Re: strong impulses when actuating joints

Postby blackbird_dream » Tue Oct 09, 2018 8:00 am

I changed solvermode to 0 thks to Sweenie.
It seems worse.
I also tested 2. it's explosive.
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