Making things move tutrorial

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1

Hello i did this tutorial and got problem with lesson number 4.
I applied driver markers but after running kinematic analysis this was shown:

  1. Kinematics (Operation: Main.MyStudy.Kinematics):
    0.0) PreOperation (Operation: Main.MyStudy.Kinematics.PreOperation):
    0.0.0) InitialConditions (Operation: Main.MyStudy.InitialConditions):
    0.0.0) …Design variables have been updated.
    0.0.1) …Load-time positions have been re-established.
    0.0.2) …Kinematic analysis completed. The kinematic constraints have been resolved.
    0.0.3) …Initial conditions are fully updated.
  2. Kinematic analysis…
    Failed to resolve kinematic constraints. Newton relaxation too small. (final kin. error = 3.387357E-003)
    Constraint no. 0 above error tolerance 0.001000, error = 0.003387.
    Constraint no. 37 above error tolerance 0.001000, error = 0.001197.
    Constraint no. 43 above error tolerance 0.001000, error = 0.001143.
    Constraint no. #0 in ‘Main.MyModel.C3D.Model.L001.LinDrv’ above error tolerance 0.001000, error = 0.001197.
    Constraint no. #0 in ‘Main.MyModel.C3D.Model.L002.LinDrv’ above error tolerance 0.001000, error = 0.001143.
  3. …Kinematic analysis terminated

But when I added Joint connecing segment with Global reference frame, everything worked fine like in tutorial.
I have question about driver markers, why this happened and why if they are Ctype Soft, no solution to kinematic analysis was found ?

2

Hi,
I don’t fully understand what your question or problem is.

If you want to drive one or several segments, you need enough information on the segment positions. By adding a joint to global, you limit the DOF and therefore it has enough information from the markers.

3

Hello
My problem was that in this lesson i wasn’t able to run kinematics operation only with c3d data. After adding joint connected with ground, then it started to move.

The model also moved in case where there was no connection to the ground, but one of c3d driver markers was CType Hard, then one was exactly in place and others were out of place.

My question is what CType Soft does ?

Why the program ties to find solution to kinematic constrains when i only need it to stop iterating at some point, if I understand correctly?

4

Hello
My problem was that in this lesson i wasn’t able to run kinematics operation only with c3d data. After adding joint connected with ground, then it started to move.

The model also moved in case where there was no connection to the ground, but one of c3d driver markers was CType Hard, then one was exactly in place and others were out of place.

My question is what CType Soft does ?

Why the program ties to find solution to kinematic constrains when i only need it to stop iterating at some point, if I understand correctly?

5

CType soft should be used in combination with over-determinate kinematcs solver. This means you have more markers then necessary to solve the problem kinematically.

there is a paper by Andersen et al describing the function.

6

hello Amir
I would be interested in the paper by andersen you mention above.
Could you please sent me the title and/or information where to find it?
Thanks a lot!

kind regards
Tobias

7

Hi Tobias,

Please have a look here.

Kind regards,
Pavel

8

Hello Pavel
Thanks a lot!
Kind regards
Tobias