problem with AnklePlantarFlexionMoment

Hi,

In the attachments I added three pictures of ankle moment of forces. One is the required value of the moments of forces, one contains the value of the current moments of forces and one the moment of force with the signal to the opposite. I have a few questions for you:

  1. Why is the moments of forces so different with the signal in the forceplate turned to negative?
  2. What can be the cause that the current moment of force is much lower than the required moment of force?(I checked all the muscles in the file but they are switched on)
  3. Is the correct muscle requitment solver used?

Best regards,

Hans

Hi Hans,

I am not sure what you mean by “so different”… of course if you change the force of the plate to the oposite then it pulls on the foot instead of pushing, so the moment goes negative. Or did you expect to have a negative moment exactly symetric to the normal positive one?

The first thing to check is where does your required moment come from. Did you get it from another software/model? If so you have to take into account differences between the models (joint type and orientation, anthropometry, point of application of the GRF on the foot segment, …).

When using predefined external loads like the force plate, the recruitment solver will not change the equivalent joint moment, only the sharing of this moment between the muscles.

Best regards, Sylvain.

Hello,

Thank you for your reply. I uploaded my model because I am not sure if certain settings are correct for my data. I also upload some files which are adjusted in my model to let it work.The c3d file is coming from software which has a different global reference frame. My questions for you are:

1.Where can I find the grf point and if it’s not correct for my model how can I change it?

  1. I think the moment arm in my model is not correct since the ankleplantarflexionMoment in my model is 20 Nm lower than it should be which is a significant difference.

  2. There is nothing wrong with the muscles since the generated force in the anklejoint is exactly what it should be. My question is are the signals in my model in the correct order since the standard dataset in the model has a different reference frame in the forceplates?

Best regards,

Hans

Hi,

Did anyone of you already take a look to my model? I am really waiting for your reply.

Best regards,

Hans

Hans,

I tried to load your model for a while, but I couldn’t. What AMMR was that in? 1.4?

I also suggest that you do not change files in the Body Folder, as this makes it very tough for us to replicate the model. You can easily add additional nodes and measures in the model without going into the body.

was it made in 1.3 or earlier?

Hi,

The AMMR version is 4. I don’t know why it isn’t loading well I will upload the other model without the spherical joints instead.

What’s the error this model gives?

Best regards,

Hans

Hi,

I uploaded the model without the spherical joints.

Best regards,

Hans

A very quick comment:

when I look into your C3D file, I can see that you have Type 2 plates, but you use ForcePlateType4.any.

Was that done intentionally?

I’m also getting errors about ‘RasiMarker’ and ‘ThoraxNode’ from FootNodesDefinv.any, but I can outcomment those.

Hi,

I use forceplatetype4 Any with two forceplates I will upload my forceplatetype4.any file to make it easier for you. The reason is that de forceplatetype4autodetection is not working for my model.

Best regards,

Hans

Hi,

Please let me know if the model will run with this forceplatetype4.any file.

Best regards,

Hans

Hans,

Unfortunately, your model is very complex and little bit messy. I get many error messages, meaning that you changed several things in the body folder. I managed to load the model by out-commenting several things. Unfortunately I’m getting an error message that it is not indeterminate and that several drivers are missing

Model is kinematically indeterminate : Position analysis failed : 139 independent constraints and 147 unknowns

I’m sorry to sound stupid, but it is tough for me to understand everythign you made in your model. Could we approach that differently?

  1. take the GaitLowerExtremity Model of a new repository 1.4.1 and make it load your C3D?
  2. What is your final goal?

Hi,

I am busy to apply my model in a standard bodymodel template when I have it working I will upload it.

Best regards,

Hans

Hi,

I uploaded the model in a standard template except for the forceplatetype4.any file which I added in the zip file. What I want to achieve is that I need to compare the moments of forces with another software tool. And what I need to know whether the settings are correct since I get a deviation in the AnkleplantarFlexion moment of 20Nm. Which I showed in the diagrams earlier.

Further I need to know if the GRF point is correct for my dataset.

Best regards,

Hans

Hi,

Please let me know if it’s working.

Best regards,

Hans

Hans,

the model loads and I could find some errors, but there is still something wrong…

  1. Please use the attached ForcePlateType2.any instead of your ForcePlateType4.any! This will correct the ref frame in the force plates.

  2. Please also correct the gravity in your main file
    Gravity ={0, -9.81, 0};

Did you introduce any connections from the model to global? Somehow loads disappear going up from the ankle to the hip…

Hi,

What do you mean with loads are going from the ankle to the hip?

Best regards,

Hans

Sorry, that sounds wrong, I mean that the dimension of the Ankle Reaction Forces seems ok, the Knee is very low and Hip far too low (muscles are not producing anything in the hip)…

Hi,

The only connections I made in my model to the global reference frames are own defined segment orientations in the pelvis segment. I didn’t change the joints are driveroptimized file for my model.

Best regards,

Hans

Here it is:

in “JointsAndDriversOptimized.any” you switched the reaction type on in the LegTD!!!
Reaction.Type={On,On,On,On,On,On}; //wrong

please turn them Off again, then the loads make sense!

Reaction.Type={Off,Off,Off,Off,Off,Off}; //correct

hi,

One remaining question: The second moment of force in the ankleplantarflexionMoment is still deviated. The negative part is too negative and the positive part is too low. Is there an explanation for this or is everything correct applied now?(I used your forceplate file, adjusted the gravity switched the reaction.type for all drivers to off).

Best regards,

Hans