AnsweredAssumed Answered

subassembly mates behave really strange in motion analysis

Question asked by Jianyuan Zhang on Jan 5, 2017
Latest reply on Feb 22, 2017 by James Crider

Like • Show 0 Likes0
Comment • 4

Hello,

I am building a robotic arm on a bigger device to use it pick and deliver stuff, so this bigger device is considered a top-level assembly and the robotic arm is the sub-assembly in this case, the problem is the mates in the subassembly work perfect, but when I make an animation in the top-level assembly, I need to animate how the robotic arm moves( particularly using the hinge mate at each pivot) the mates in the sub-assembly do not work any more, and all the sub-assembly parts start to be flying all over the places. but these mates work properly in the model. I uploaded the file and the screenshot it could be clear for you.

the way it is if I animate the process.the way it is in the model

Any help would be appreciated!

Tony

Attachments

solidworks.rar24.7 MB

No one else has this question

Outcomes

Alessandro Tornincasa Jan 6, 2017 12:56 PM

Tony,

I haven't looked at your assembly, but I suspect the most likely cause is that your subassembly is solved as rigid. You should male It flexible. For more info watch this video: Flexible Sub Assemblies in SolidWorks - YouTube

Actions

Jianyuan Zhang @ Alessandro Tornincasa on Jan 6, 2017 1:09 PM

hello,

Thanks for the help, but all the mates in all the subassembles are set to be fleixble already, that's why I can move it in the top level assembly

Actions

Alessandro Tornincasa @ Jianyuan Zhang on Jan 17, 2017 2:04 AM

Jianyuan,

I had a very quick look at your assembly. A couple of comments:

- there are many red bars in your timeline, which indicate that some components positions cannot be calculated

- your assembly includes a large number of flexible subassemblies

These have been notorious in the past for causing issues with Motion studies. Things have improved over years, but in a study like yours with many motions I would suggest using a more robust approach:

- don't use flexible subassemblies

- create as many subassemblies as needed that contain only components that form rigid Groups (no relative motions)

You will see a much more predictable behaviour.

Alex

Actions

James Crider Feb 22, 2017 4:57 PM

Month late, but something to consider:

As Alex suggests, flexible subassemblies are problematic in Motion Analysis. You're better off bringing in the components of the arm into the top-level assembly. Group them in a folder if you like, for BoM simplicity, but they should be their own parts.

The other thing I've noticed in my own work is that the typical mates used for pivots (concentric, coincident or width, hinge, slot), don't work so well in Motion Analysis. Have to think like you would back when this bit of code was written nearly 30 years ago and set axis and point mates for the pivoting components: an axis in each pivot hole, and points where you'd set the sliding surfaces coincident. Do coincident mates for each axis, and again for the point, and you'll have a joint Motion Analysis will understand.

Jim

Actions

4 Replies

Alessandro Tornincasa Jan 6, 2017 12:56 PM
Mark Correct
Correct Answer
Tony,
I haven't looked at your assembly, but I suspect the most likely cause is that your subassembly is solved as rigid. You should male It flexible. For more info watch this video: Flexible Sub Assemblies in SolidWorks - YouTube
Like • Show 0 Likes0
Actions
- Jianyuan Zhang @ Alessandro Tornincasa on Jan 6, 2017 1:09 PM
  Mark Correct
  Correct Answer
  hello,
  Thanks for the help, but all the mates in all the subassembles are set to be fleixble already, that's why I can move it in the top level assembly
  Like • Show 0 Likes0
  Actions
  - Alessandro Tornincasa @ Jianyuan Zhang on Jan 17, 2017 2:04 AM
    Mark Correct
    Correct Answer
    Jianyuan,
    I had a very quick look at your assembly. A couple of comments:
    - there are many red bars in your timeline, which indicate that some components positions cannot be calculated
    - your assembly includes a large number of flexible subassemblies
    These have been notorious in the past for causing issues with Motion studies. Things have improved over years, but in a study like yours with many motions I would suggest using a more robust approach:
    - don't use flexible subassemblies
    - create as many subassemblies as needed that contain only components that form rigid Groups (no relative motions)
    
    You will see a much more predictable behaviour.
    
    Alex
    Like • Show 0 Likes0
    Actions
James Crider Feb 22, 2017 4:57 PM
Mark Correct
Correct Answer
Month late, but something to consider:
As Alex suggests, flexible subassemblies are problematic in Motion Analysis. You're better off bringing in the components of the arm into the top-level assembly. Group them in a folder if you like, for BoM simplicity, but they should be their own parts.

The other thing I've noticed in my own work is that the typical mates used for pivots (concentric, coincident or width, hinge, slot), don't work so well in Motion Analysis. Have to think like you would back when this bit of code was written nearly 30 years ago and set axis and point mates for the pivoting components: an axis in each pivot hole, and points where you'd set the sliding surfaces coincident. Do coincident mates for each axis, and again for the point, and you'll have a joint Motion Analysis will understand.

Jim
Like • Show 0 Likes0
Actions

subassembly mates behave really strange in motion analysis

Attachments

Outcomes

Related Content

Recommended Content