Kinematic analysis failure

Dear AnyBody support:

I am trying to use a c3d file acquired from a subject walking on a treadmill to drive the model. I included 4 gait cycles and started with MotionAndParameterOptimization Model. I read the wiki and commented out the bad reflective markers, re-orientated the forceplates, and adjusted the positions of the bone markers as good as I can. It took very long to get optimization convergence but Failed to resolve kinematic constraints. I attached both my model files and complete error messages.

Any help will be appreciated!

-Phoebe

) RunMotionAndParameterOptimizationSequence (Operation: Main.RunMotionAndParameterOptimizationSequence):

Macro command : RunMotionAndParameterOptimizationSequence(1:5)> operation Main.Studies.ParameterIdentification.ParameterOptimization

Macro command : RunMotionAndParameterOptimizationSequence(2:5)> run

2.0.0) Operation Sequence: (Operation: Main.Studies.ParameterIdentification.Analysis):
2.0.0.0) Kinematics (Operation: Main.Studies.KinematicStudyForParameterIdentification.Kinematics):
2.0.0.0.0) PreOperation (Operation: Main.Studies.KinematicStudyForParameterIdentification.Kinematics.PreOperation):
2.0.0.0.0.0) InitialConditions (Operation: Main.Studies.KinematicStudyForParameterIdentification.InitialConditions):
2.0.0.0.0.0) …Design variables have been updated.
2.0.0.0.0.1) …Load-time positions have been re-established.
2.0.0.0.0.2) …Kinematic analysis completed. The kinematic constraints have been resolved.
2.0.0.0.0.3) …Initial conditions are fully updated.
2.0.0.0) Kinematic analysis…
2.0.0.69) …Kinematic analysis completed
2.0) Optimization (Operation: Main.Studies.ParameterIdentification.ParameterOptimization):
2.0) Optimization step (Operation: Main.Studies.ParameterIdentification.ParameterOptimization):
2.0) Evaluating KKT conditions (Operation: Main.Studies.ParameterIdentification.ParameterOptimization):
2.0) Evaluating the objective function (Operation: Main.Studies.ParameterIdentification.ParameterOptimization):
2.0) Calculating a new search direction (Operation: Main.Studies.ParameterIdentification.ParameterOptimization):


2.0) Optimization step (Operation: Main.Studies.ParameterIdentification.ParameterOptimization):
2.0) Evaluating KKT conditions (Operation: Main.Studies.ParameterIdentification.ParameterOptimization):
2.0) Evaluating the objective function (Operation: Main.Studies.ParameterIdentification.ParameterOptimization):
[COLOR=red]Optimization converged

Macro command : RunMotionAndParameterOptimizationSequence(3:5)> classoperation Main.Studies.ParameterIdentification “Save design” --file="…/Input/LowerBody-L00I00WXC20-OptimizedParameters.txt"

Main.Studies.ParameterIdentification : Saving design…

Macro command : RunMotionAndParameterOptimizationSequence(4:5)> operation Main.Studies.MotionOptimization.Kinematics

Macro command : RunMotionAndParameterOptimizationSequence(5:5)> run

5.0) Kinematics (Operation: Main.Studies.MotionOptimization.Kinematics):
5.0.0) PreOperation (Operation: Main.Studies.MotionOptimization.Kinematics.PreOperation):
5.0.0.0) InitialConditions (Operation: Main.Studies.MotionOptimization.InitialConditions):
5.0.0.0) …Design variables have been updated.
5.0.0.1) …Load-time positions have been re-established.
Failed to resolve kinematic constraints. Newton relaxation too small. (final kin. error = 9.409783E-006)
Constraint no. 217 above error tolerance 0.000001, error = 0.000002.
Constraint no. 287 above error tolerance 0.000001, error = 0.000005.
Constraint no. 288 above error tolerance 0.000001, error = 0.000009.
Constraint no. 289 above error tolerance 0.000001, error = 0.000008.
Constraint no. 290 above error tolerance 0.000001, error = 0.000004.
Constraint no. 291 above error tolerance 0.000001, error = 0.000008.
Constraint no. 292 above error tolerance 0.000001, error = 0.000001.
Constraint no. 293 above error tolerance 0.000001, error = 0.000001.
Constraint no. 294 above error tolerance 0.000001, error = 0.000002.
Constraint no. 300 above error tolerance 0.000001, error = 0.000002.
[SIZE=1]ERROR(OBJ.MCH.KIN3)[/SIZE] : [SIZE=1]D:/Gai…sis/A…r/S…3/L…W/M…l/Kinematics.any(75)[/SIZE] : [SIZE=1]MotionOptimization.InitialConditions[/SIZE] : Kinematic analysis failed in time step 0

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Just an update. I fixed the problem.

Thanks.

How did you fix the problem?

Dear tgambo:

I tried many different things. What I would suggest is to go back to your motion files and see if you can improve the marker trajectories. I am a beginner, too; I wish the my limited experiences will be helpful to you:

  1. after loading your model and before running MotionANdParameterOptimization, take a look at the positions of all the markers and see if there is a big difference between red and blue dots. If there is, you better go back to C3D file and make modifications there (use a different marker if there is a cluster of markers to choose from, try a different filter, etc.) If there is moderate difference, you can go to the ModelSetup->Markers and make changes to the coordinates. There is a full tutorial on this topic.

  2. check the initial posture of your model in TrialSpecificData

  3. if all above fails, you probably have to manipulate the directions of optimizations and weight factors. There is a tutorial on that too, unfortunately it's more like a trial and error type of work and it could be time consuming.

Hope it helps and good luck!

-Phoebe