Adjustments of Ankle Joint gaitlowerextremity AMMR V1.2

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21

Hi Hans

I can see from the previous postings in this thread that you have replaced the revolute joint with a spherical joint?

if this is the case it could be that for this specific timestep the muscle configuration does not have anyway to balance the model.

Since you changed the knee this is my first suspicion please try to add an anykinrotational in the knee and add an AnyReacForce to one dof at the time of this measure until the model runs…

This might give you an idea on the cause of the problem.

Best regards
Søren

22

Hi,

Thank you for your reply where should I add that AnyReacForce?

Best Regards,

Hans

23

Hi Hans,
add a AnyKinRotational between the two nodes used for the knee joint.
Use a Measureorganizer to pick one entity at the time and apply the reaction force to this.
Best regards,
Sebastian

1 Like
24

Hi,

I have added a rotational in the Knee and the inverse Dynamics will run. But after adding AnyReacForce like this

[SIZE=3]AnyReacForce [/SIZE]KneeForce[SIZE=3] [/SIZE]=[SIZE=3]
[/SIZE]{
[SIZE=3][/SIZE]Type[SIZE=3] [/SIZE]=[SIZE=3] [/SIZE]Off;
[SIZE=3]AnyKinMeasure[/SIZE][SIZE=3] [/SIZE]&KneeDriver[SIZE=3] [/SIZE]=[SIZE=3] [/SIZE].PatellaFlexion;
};

But I still get errors that at the end the inverse dynamics did not find a solution. Also there are huge fluctuations in the forces and torques? What to do?

Best Regards,

Hans

25

Hi,
if it fails again then something is not carried. You also made some changes on the ankle, right? Please make sure that this is not the problem. But it could of course also be the knee, please provide the whole implementation of the rotational measure and the reac force.
Best regards,
Sebastian

26

HI,

I have uploaded the file.

Best regards,

Hans

27

Hi,
have you tried to put another Reacforce on the KneeRotation?
I think this one may also cause problems.
Best regards,
Sebastian

28

Hi,

Do you mean a second one?

Best Regards,

Hans

29

Yes, you fixed varus valgus if I’m right, but axial rotation is still free.
Sebastian

30

Hi,

I have added more reaction forces and the analysis runs completely. But the torques and the forces have a lot of fluctuations. It is more a seismologic torque. Is it possible to fix this?

Best Regards,

Hans

1 Like
31

Hi Hans,
the problem can be that a AnyReacForce has no cost for the muscle recruitement. Meaning the system would prefer to activate/use a AnyReacForce instead of a muscle. You can try to introduce AnyGeneralMuscles with high strength instead of the AnyReacForce. You can play a little with the strength value of those. You should check that they do not influence your muscular activity. Please have a look at the Ref Manual for the definition.
Best regards,
Sebastian

32

Hi,

I only do not know how to define the musclemodel.

Best regards,

Hans

33

Hi Hans,

You can use the simple muscle model where you only input the constant strength of the nuscle like this:

AnyMuscleModel <ObjectName> =
{
F0 = <Strength>;
};

Best regards, Sylvain.