Gait lower extremity model

Hi,

I’m having problems running the motion and parameter optimization in the gait lower extremity models. I keep getting the following errors:
Position analysis failed : 268 independent constraints and 272 unknowns

  • attempts to continue (attempt no. 10)
    Constraint no. #3 in ‘Main.Studies.KinematicStudyForParameterIdentification.HumanModel.BodyModel.Right.Leg.Jnt.PatellaFemur.Constraints’ above error tolerance 0.000001, error = 0.004484.
    Constraint no. #4 in ‘Main.Studies.KinematicStudyForParameterIdentification.HumanModel.BodyModel.Right.Leg.Jnt.PatellaFemur.Constraints’ above error tolerance 0.000001, error = 0.005148.
    Constraint no. #0 in ‘Main.Studies.KinematicStudyForParameterIdentification.HumanModel.BodyModel.Right.Leg.Jnt.PatellaMovement’ above error tolerance 0.000001, error = 0.001233.
    Constraint no. #3 in ‘Main.Studies.KinematicStudyForParameterIdentification.HumanModel.BodyModel.Left.Leg.Jnt.PatellaFemur.Constraints’ above error tolerance 0.000001, error = 0.014437.
    Constraint no. #4 in ‘Main.Studies.KinematicStudyForParameterIdentification.HumanModel.BodyModel.Left.Leg.Jnt.PatellaFemur.Constraints’ above error tolerance 0.000001, error = 0.007434.
    Constraint no. #0 in ‘Main.Studies.KinematicStudyForParameterIdentification.HumanModel.BodyModel.Left.Leg.Jnt.PatellaMovement’ above error tolerance 0.000001, error = 0.001365.
    [SIZE=1]ERROR(OBJ.MCH.KIN3)[/SIZE] : [SIZE=1]C:/U…s/s…2/D…p/A…s/A…2/A…n/M…s/G…y/GaitLowerExtremity.main.any[/SIZE] : [SIZE=1]KinematicStudyForParameterIdentification.InitialConditions[/SIZE] : Kinematic analysis failed in time step 0

[SIZE=2]I’m not sure what to do from here.[/SIZE]
[SIZE=2][/SIZE]
[SIZE=2]Thanks,[/SIZE]
[SIZE=2]Brooke
[/SIZE]

Hi Brooke

I have tested your model and you are right it fails in the first step.

The reason is most likely that initial positions is really bad, you will need to adjust the initial positions to make so that it is closer to the markers. it looks like it needs to be rotated …

I tried the following setting for the pelvis rotation

AnyVar PelvisRotZ = 180;
AnyVar PelvisRotY = 0;
AnyVar PelvisRotX = 90;

This makes the orientation resonable…

However the model does not run only with these changes, there is still 268 constraints and 272 unknowns…
so four drivers are missing…

These drivers are the rotation between the pelvis and the throrax (3 dof) and the one dof in the neck. You can find examples of this in the GautVaughanModel of the repository in the JointAndDrivers.any file.

Best regards
Søren

Hi Brooke,

I managed to get the model to solve the optimisation. I’ve had to cut the c3d file due to missing markers at the start and end of the trial (R foot).

I’ve made adjustments to the trialspecific file with scaling parameters.
I’ve also moved the markers in the ModelSetup file, (changing the sRelOpt = for each marker).

Hope this helps out, I’ve not run inverse dynamics but hopefully all should be well.

Attached is a static model and JaredGait dynamic trial

best wishes

Peter