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Assembly Constrains difficulties

evandene

evandene

Member
Hi all,
I'm trying to add assembly constrains to a simple Delta Robot design but it looks it is way to much to ask for Alibre design. If somebody could give me a hand, that would be wonderful. One single set of arms is no problem at all. The second arm doesn't work if you try adding all needed constrains. The third arm makes it messy.
I attached the complete package.
For your information; I have no problems when somebody copies the file for their own use.
Regards
Ed
 

Attachments

  • DELTA_ROBOT_LOGIS2.AD_PKG
    2.2 MB · Views: 7
HaroldL

HaroldL

Alibre Super User
(Note - I rebuilt the assembly in v28 sp1. Hope that's not a problem for you.)

A couple of things I noticed. Put all the the items for the arms into the arm assembly. That reduces the amount of constraints in the top assembly.

arm assy.jpg

I found that applying a coincident constraint between the end plate and the last arm assy would lock up any movement. Leaving that constraint off lets the movement take place.

coincident lock up.jpg
 

Attachments

  • DELTA_ROBOT_LOGIS2 - RECONSTRAINED.AD_PKG
    2.2 MB · Views: 3
evandene

evandene

Member
HaroldL said:
(Note - I rebuilt the assembly in v28 sp1. Hope that's not a problem for you.)

A couple of things I noticed. Put all the the items for the arms into the arm assembly. That reduces the amount of constraints in the top assembly.

View attachment 41980

I found that applying a coincident constraint between the end plate and the last arm assy would lock up any movement. Leaving that constraint off lets the movement take place.

View attachment 41979
Click to expand...
Thanks, I will give it a try. The last remark make sense, it would create even an over constraint assembly
 
evandene

evandene

Member
HaroldL said:
(Note - I rebuilt the assembly in v28 sp1. Hope that's not a problem for you.)

A couple of things I noticed. Put all the the items for the arms into the arm assembly. That reduces the amount of constraints in the top assembly.

View attachment 41980

I found that applying a coincident constraint between the end plate and the last arm assy would lock up any movement. Leaving that constraint off lets the movement take place.

View attachment 41979
Click to expand...
Okay, I made a sub-assy from the arm, including the ball-joints. The arms are made flexible, in order for the ball-joins to move around. After all of that, and re-doing all constrains, I could only move one Upper-Arm to move the Effector. The other Upper-arms can't be moved. I must conclude that Alibre is not the right CAD system for somewhat complex assembly constrains. Inventor, for example, has no problems with the same design. Still, we are happy with Alibre, do not me understand me wrong. The system is only not comparable with other systems at some points.
 
evandene

evandene

Member
HaroldL said:
Instead of trying to write out the results of my "testing" on your model, I recorded a short video showing what I was able to get from the model.


www.screencast.com

Delta Robot Constraints.mp4

Shared from Screencast.com
www.screencast.com www.screencast.com
Click to expand...
I'm impressed, thank you so much. It would be nice if the system would allow you to set a kind of constrain calculation tolerance. Maybe that would help the unexpected lockup.
Thanks again
 
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