Type 5 Force Plate

Main Forum
1

Hello,
I am trying to build a model from a .c3d file which has one type 5 force plate. The force plate data has analog signals of Fx1, Fx2, Fy1, Fy2, Fz1, Fz2, Fz3, Fz4, CH9 and CH10. The cal_matrix with the .c3d file does not have any values, which is causing us difficulties when altering the EnvironmentAutoDetection.any ForcePlateType4AutoDetection.any files. Are there there any other environment files which can accommodate force plates other then type 4?
Thanks
David

2

Hi David,

if your plate is of type 5 it should have the following characteristic data available see www.c3d.org

TYPE-5
This force platform is a portable eight channel platform manufactured by AMTI and is supplied with a 6 by 8 calibration matrix. The force platform analog outputs are Cz, Dz, Az, Bz, Yac, Ydc, Xab, Ybd. The CAL_MATRIX parameters scale the analog data from volts to Newtons.

You can not use a type 4 for this it will expect fx,fy,fz,mx,my,mz

So i think you should try to construct a new plate class. I think you do the following:

[ul]
[li]find out exactly which data is available in the .c3d and if this fits with your expectations
[/li][li] find out if your plate is a type5 ?
[/li][li]Find more documentation on the plate output, the info on www.c3d.org on the type5 is not enough for constructing this class.
[/li][li]Construct a new forceplate class based on this info and the available data.
[/li][/ul]

Best regards
Søren

3

Hi,

I have a following question regarding the force plate data. I am unable to load my force plate data into the gait model. My error massage is that Fx1 is an unresolved object.

How do i check whether my force plate data is type 4 as required by EnvironmentAutoDetection.any and if my force plate is not type 4, how can i change the configuration of my c3d data to a type 4, or go around it such that Anybody can accept the force data.

Am a beginner here. Thanks for your help.

4

BTW, found out that my force plate type is “Amti”. Unsure what that translate to.

5

Hi David,

The error means that you do have an object in your c3d file named like this.

Please have a look in the C3D file structure it will be in Main.ModelSetup.C3DInput?

Here you first need to look in the Main->C3dFileData->Group->ForcePlate folder and in that one look for the last item named type. The type describes how that data was stored for more info on this object have look here :
http://www.c3d.org/html/default.htm

If the type says type={4,4} it means that it have two plates of type 4.

To find out how the forceplate data was named in your case have a look in the main->C3dFileData->Analog->Datafiltered folder here you can see the exact naming used in your case. This differs from lab to lab.

You can not change the type of the plate you will need to use then another forceplate class, currently we have type2, typ3 and type4 as examples in the repository.

Best regards,
Søren