Use a calibration matrix for Type4 forceplate

Main Forum
1

Hello,

I tried to use a calibration matric that I had, and I don’t unserstand the error message. I tried to specify my matrix in the EnvironmentAutoDetection folder.

Could you help me and explain how to use a calibration matrix in anybody?

I use AMS 5, and AMMRV1.4
Here attached is the model I use.

Thank you in advance,

Best regards,

Claude Pothrat

2

Hi Claude,

  1. First, it seems that this force plate is Type2, not Type4.
    You can check the type of force plate here:
    Main.ModelSetup.C3DFileData.Groups.FORCE_PLATFORM.TYPE.Data
    In your C3D file, this value is 2.
    So basically, there is no need to use the CAL_MATRIX.
    But if you believe that this is really the force plate type 4,
    then you should put your own CAL_MATRIX which does not exist in your C3D file.

  2. In your C3D file, there is only one force plate.
    When you used the Class Template in the “EnvironmentAutoDetection.any” file,
    you should use ‘No=0’ when there is only one force plate in the C3D file.
    Because you used this value as ‘No=1’, this was the reason of error in your original model.

Attached please find the zip compressed file of your model that I’ve modified.
I also modified the position of T10 marker to pass the MotionAndParameterOptimization process without problems.

I hope this may help you.

Best regards,
Moonki

3

Hi Moonki,

Thank you for your help!
There is still something I don’t understand. The forceplate used in the model is indeed a type 2, but it is provided with a calibration matrix.
Theorically, I should have the same results if I use datas already transformed by vicon, or analogic datas with a calibration matrix?
I tried to use analogic datas directly in anybody, and to use the matrix, but I don’t have the same results.

Can you precise what exactly is the difference between type 2 and type 4, as all forceplates are provides with calibration matrices?

Thank you very much,

Very best regards,

Claude Pothrat

4

Hi Claude,

As far as I know, the force plate type2(usually AMTI) does not provide the calibration matrix as an output in the C3D file.

You can find the detail information about the force plate types here:
http://www.c3d.org/HTML/default.htm?turl=type.htm

And here is the description of the force plate type4:
http://www.c3d.org/HTML/type4.htm

I hope this may be helpful to you.

Best regards,
Moonki

5

Hi,

Thank you.I had indeed already read these descriptions. Most of the forceplates (included AMTI forceplates) are in fact provided with calibration matrix, that’s why I didn’t understand.
I just wanted to know if there were other things to know about it, but obviously, calmatrix is the only difference.

Thank you very much,

Best regards,

Claude

6

Hi,

One thing that you can try is to see the ground reaction force vector at the force plate when you are using or not using the calibration matrix.

Then you can check which is correct. :slight_smile:

Best regards,
Moonki