linear motion

[YvP]

Dear AnyBody members,

I want to run my AnyMoCap model with the CAD model. In my CAD model, I have one Linear guide which has linear motion. I have used Three coincident and one limit angle constraints in Solidworks to assemble this linear guide and I have tried to run that model in AnyBody, but it is showing some error. In attachments, you can find some Photo of that Linear guide for better understanding. Can you please help me to solve this problem?

Best regards
Yvp

[mkjung9980]

Dear Yvp,

Could you please update your profile (name, organization, etc) so that we can figure out which users are asking the questions. Afterwards, we will try to figure out how to support you.

Thanks for your understanding.

Best regards,
Moonki

[YvP]

Hello Mr. Moonki,

Thank you for your reply. I have just updated my profile.

Best regards,
Yvp

[mkjung9980]

Dear Yvp,

Thanks for your updates.

Here are some suggestions.

1. AnyExp4SolidWorks does not support an instance of the LimitDistance type mates. So those mates will not be translated.

2. If you would like to make a kind of prismatic joint between two parts, I would like to suggest you to try the following combination of two different mates:
   1 LINE-LINE Coincident mate
   1 POINT-PLANE Coincident mate
   
   These two mates will add 5 constraints in the model.

I hope this may be helpful to you.

Best regards,
Moonki

[YvP]

Hello Mr. Moonki,

Thank you very much for your reply. The slider is now working perfectly.
I have one more problem. In my CAD model I have total of 8 joints, one of them is the Slider Joint (Prismatic joint) and 7 other hinge joints. When I am adding that whole model in AnyBody, I am getting the following error.

Model is kinematically over-constrained (1 unsolvable constraints found).
I have used 2 drivers to attached this CAD model to human Model with 11 constraints.

Can you plese tell me, how can I solve this problem?

Once again, thank you very much.

Best regards,
Yvp

[mkjung9980]

Dear Yvp,

If you are correct, if there are 1 prismatic joint and 7 hinge joints,
it seems that there are 8 degrees of freedom internally in your mechanism.
But if there is no segment that is attached to the global coordinate system, also there are another 6 degrees of freedom .

So I would assume that there are totally 14 degrees of freedom.

If you used 2 drivers and 11 constraints, then it seems that the number of constraints that you used seems to be correct.

If you can upload your model on the debug section then we may be able to have a look at it: http://forum.anyscript.org/forumdisplay.php?f=21

Best regards,
Moonki

[YvP]

Respected Mr. Moonki,

Once again, thank you very much for your quick response. Now i konw that, where was the problem in my mechanism. In my mechanism there is one close loop with two links, which I run in inverse dynamics as a close loop, and its not working. But when I opened the loop than the inverse dynamics is runnig perfectly. Attachment shows the photo of the mechanism and I have explained in detail.

Best regards,
Yvp

[mkjung9980]

Dear Yvp,

If you want to make a closed loop 4 bar mechanism in 3D space, let’s try to calculate the number of DOFs as well as the number of constraints.

1. The number of DOFs = 6 X 4 = 24

2. The number of Constraints then should be 24 as well.

Let’s assume that there is only 1 remaining DOFs in this mechanism.

It means that you should define 23 constraints in this mechanism.

There are many combinations that will provide 23 constraints in total.

1 fix mate (6 constraints) + 3 hinge mate (15 constraints) + 1 line-point coincident mate (2 constraints) = 23 constraints.

The key point here is, you should not generate too many constraints in your mechanism.

I hope this may help you.

Best regards,
Moonki

[YvP]

Hello Mr. Moonki,

Thank you very much for your precious time and solution. i will try that solution.

Best regards,
Yvp