Kinematic Operation Error

Main Forum
1

Hi there,

When I run the Kinematic tool for my FreePosture model I always get this error near the end:

[i]

  1. Kinematics (Operation: Main.Study.Kinematics):
    0.0) PreOperation (Operation: Main.Study.Kinematics.PreOperation):
    0.0.0) InitialConditions (Operation: Main.Study.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…
    ERROR(OBJ1) : C:/U…s/j…1/A…a/R…g/A…y/D…s/A…o/A…n/M…s/M…e/M…l/I…s/TrunkDrivers.any(8) : PelvisGroundDriver : Time, ‘t’, has an invalid value for this interpolation
    [/i]
    What does this mean? I’m using the same time array for all of my drivers.
2

Hi Jared,

This means that you are trying to go beyond the data in your input file.

So if your time values goes from 0 to 2 sec and and the tEnd of the study is 3 sec you would get this errror.

Please ensure that the tStart and and tEnd reflects the time you have in the input files.

Best regards
Søren

3

Hi

Could this error have something to do with the kinematics solver type in the AnyBodyStudy?
I have just started looking into motion capture models. I looked into the AnyInputBVH class example (from the reference manual) and I tried to go further by adding a human model. I added the same BVH file from the example into the free posture model and the Human template, changing the tStart and tEnd correspondingly. In both the cases, I observed that putting the conditions:

Kinematics.SolverType = KinSolOverDeterminate;
InitialConditions.SolverType = Kinematics.SolverType ;

gave me the error:
ERROR(OBJ1) : C:/U…s/d…1/D…p/A…s/M…N/A…H/F…e/CodeBVH.any(1) : BVH_Model.Model.Hips.Driver : Time, ‘t’, has an invalid value for this interpolation

If I comment out these two lines, then the kinematic analysis goes ahead without any problems.

I am using AnyBody v6.0.7 and AMMR 1.6.5. Could you explain to me why this happens?

Regards
Dave

4

Dear Dave,

Thanks for writing here and we know that sometimes such a situation may happen when soft kinematics solver is enabled as you mentioned.

A very quick solution which may be helpful to solve this issue is to narrow down the gap between tEnd and tStart values in the AnyBodyStudy class instance.

tStart = Your_Original_tStart +[b]2[/b]*Kinematics.ApproxVelAccPerturb; 
tEnd = Your_Original_tEnd -[b]2[/b]*Kinematics.ApproxVelAccPerturb;

Like the above code, please try to adjust your tStart and tEnd values in order to narrow down the range in between.

Best regards,
Moonki

5

Dear Moonki

Thank you for your reply.

I tried your suggestion in the code and it solved the problem. However, I do not understand what exactly happens and how narrowing the time range solves the problem. I am afraid that if this solution fails in another case, I will be clueless about how much the gap should be narrowed… Anyway, at least I will know where to write then :slight_smile:

Best regards
Dave

6