Joint locks with Newton

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elia.trv
Posts: 3
Joined: 05 Sep 2017, 16:23

Joint locks with Newton

Postby elia.trv » 05 Sep 2017, 16:55

Hello,

I'm having a problem with joints using the Newton Dynamic Engine.
I'm using a robotic arm to interact with a door which joint has a position range from 0 to 100 deg.
The door works well when moved inside this interval, but gets completely locked when reaches one of the two limits (0 or 100 deg).
The door's joint is in torque/force mode, motor enabled, target velocity 0 and max torque 100 mN*m.
Is there a way to solve this?

Thank you

coppelia
Site Admin
Posts: 6058
Joined: 14 Dec 2012, 00:25

Re: Joint locks with Newton

Postby coppelia » 06 Sep 2017, 09:04

Hello,

what happens with the other engines? Can you post the scene that illustrates your problem?

Cheers

elia.trv
Posts: 3
Joined: 05 Sep 2017, 16:23

Re: Joint locks with Newton

Postby elia.trv » 09 Sep 2017, 11:57

what happens with the other engines?


Hello,

With other engines, Bullet for example, the joint doesn't lock but it's very "elastic" and allows movement also in directions in which it shouldn't.

With Newton this happends:
https://youtu.be/6xo7KmdVVjI

And here is the scene:
https://www.dropbox.com/s/agddpo79vbdri ... U.ttt?dl=0

Thank you

coppelia
Site Admin
Posts: 6058
Joined: 14 Dec 2012, 00:25

Re: Joint locks with Newton

Postby coppelia » 10 Sep 2017, 16:35

The problem seems to be linked to the Newton Engine, since the other engines do not show the blocking. Try using the Vortex engine, since it will give you the best simulation results. If however you still wish to use the Newton engine, then you will have to use a workaround, e.g. by placing an invisible obstacle just before the door is completely opened (so that the door does't block at its joint limit, but rather at the collision point).

Then, make sure about several things: if you visualize the collision point in your scene (e.g. with model Models/other/contact display.ttm), you will notice that the robot can collide with itself (the joint limits for the robots have not been set).

Cheers


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