ForcePlateType3 COP

Hi there,

As suggested by Moonki on another thread ( I have uploaded my model for debug.

The files included are the ones I have changed. Everything else is as per the GaitLowerExtremity model in AMMR 1.5
I am using AMS 5.3

The problem is the location of the centre of pressure being at the centre of the force plate and not under the foot.

Any help would be much appreciated. Thanks!


Hi Sandy,

First, attached please find two modified force plate type 3 class template files.
You can just copy these new files into your ‘\AMMR\Body\AAUHuman\ToolBox\Mocap’ folder to overwrite.

Let me explain some issues regarding this force plate class template.

  1. When I looked your C3D file, there are 7 force plates. And it seems that you want to use the force plate number 6 and 7. And those are type 3 force plates.
    From the information of C3D files, our force plate class templates would use several values. We had assumed that every force plate in the C3D file have the same ORIGIN values.
    But in your case because there are different types of force plates, our assumption didn’t work. So I modified our class template to choose the right ORIGIN value of a specific force plate. In your C3D file, it would be (175, 275, 22).

  2. According to the C3D specification, the z value of ORIGIN should contain the distance between the force plate origin and the surface of the force platform.
    Since the force platform z-axis projects down, this value will normally be negative as it stores the distance within the force plate coordinate system.
    But in your case, this value is 22 so positive. So I had to modify the class template to shift the sign of this value if the value is positive.

You can see the detail information of the force plate type 3.

Of course we will apply this change into our future release of AMMR.

Thanks for providing us a good example.

Best regards,

Hi Moonki,

That’s brilliant. Thanks for your help, I really appreciate it!