Inventor General Discussion

Inventor General Discussion

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RobJV
Posts: 558
Registered: ‎07-14-2004
Message 1 of 4 (257 Views)
Accepted Solution

Dynamic Simulation Spatial Joint

257 Views, 3 Replies
11-01-2013 09:33 AM

Hi,

 

I have an assembly where balls roll down tracks and are picked up by cradles on chains that are driven by sprockets attached to an electric motor.  The simulation seems to be running fairly smoothly (if not painstakingly slow) but about half way through one of the balls (at rest) comes flying off the side of the track.  (does not make physical sense)  I assume it is due to a spatial constraint "acting funny".  The only reason the spatial constraint is in there is to allow the ball to move in the first place. 

 

I am fairly new to dynamic simulation so I do not completely understand why I have to put a spatial constraint in my assembly as opposed to telling Inventor that I simply want the ball to move. (I understand adding joints to allow degrees of freedom.) Is there not another way to allow a ball to begin movement?

 

Sorry I cannot attach the assembly here - just checking to see if somebody has some helpful hints.

 

Thanks!

 

Inventor 2013

Click on the Spatial Joint.

You should see two coordinate systems highlight - one the ball and one on the reference used when creating the joint.

Is the reference a part that never moves (Grounded Group)? (If it isn't, I think it should be.)

 

Try this (no idea if it will work).

Go to the Properties of the Spatial joint an click on each DOF tab.

Is Postion 0 on each?  If not, right click and select Set offset.

 

Spatial.png

 

*Expert Elite*
JDMather
Posts: 28,056
Registered: ‎04-20-2006
Message 2 of 4 (251 Views)

Re: Dynamic Simulation Spatial Joint

11-01-2013 09:51 AM in reply to: RobJV

Click on the Spatial Joint.

You should see two coordinate systems highlight - one the ball and one on the reference used when creating the joint.

Is the reference a part that never moves (Grounded Group)? (If it isn't, I think it should be.)

 

Try this (no idea if it will work).

Go to the Properties of the Spatial joint an click on each DOF tab.

Is Postion 0 on each?  If not, right click and select Set offset.

 

Spatial.png

 

Please mark this response as "Accept as Solution" if it answers your question.
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Mentor
RobJV
Posts: 558
Registered: ‎07-14-2004
Message 3 of 4 (236 Views)

Re: Dynamic Simulation Spatial Joint

11-01-2013 10:49 AM in reply to: JDMather

Hi JD,

 

I changed my spatial joint reference to a part that does not move and it worked.  Thanks! 

 

My simulation runs for a few more seconds and now I have to figure out why it stops. More investigating. :smileyhappy:

 

Rob

Mentor
RobJV
Posts: 558
Registered: ‎07-14-2004
Message 4 of 4 (223 Views)

Re: Dynamic Simulation Spatial Joint

11-01-2013 01:04 PM in reply to: RobJV

I had another spatial joint that was using a moving part as reference.  Was able to change that as well and for now things seem to work.  Thanks JD.

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