Method of change ForcePlate data

Main Forum
1

I had some attempts to modify ForcePlate data in gait model.

I was modified this “ForcePlateType2AutoDetection” d[FONT=Arial]eclaration To change[/FONT] ForcePlate data
#include “…/…/…/Body/AAUHuman/ToolBox/Mocap/ForcePlateType2AutoDetection.any”
there is “Load” AnyFunInterpol in the “ForcePlateType2AutoDetection” and that folder has Ground force and Moment data. Therefore I think that if i multiply any value in that data, i can change ground force freely.

and here is the code of load AnyFunInterpol
[i]// modified Forcedata//
AnyFunInterpol load ={
Type=PiecewiseLinear;
T=.Time;
Data={Fx*0,Fy*0,Fz*0,Mx*0,My*0,Mz*0}; // modify GRF Force, Moment
// Data=.Cal’*{.LowPassFilter(Fx),.LowPassFilter(Fy),.LowPassFilter(Fz),.LowPassFilter(Mx),.LowPassFilter(My),.LowPassFilter(Mz)};

};[/i]

and, it seems to be works…
Cause GRF Forces and Moments are changed.

but there is some problem.

I was compared with standard data(nonmodified) with modified data.

GRF Forces and Moments are changed, but Knee kinetics are not changed, and pelvis residual too.

And Knee kinetics are consist of MedioLateralForce, ProximoDistalForce, AnteroPosteriorForce,AxialMoment , LateralMoment ,KneeFlexion.

Is there any problem with this Method? I want to solve this problem
and Is there any Mathod to change grf data freely

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2

Hi,

Your method is working correctly. I just tried it and the knee forces are modified as expected.

Maybe the file with the modification was not loaded, or you looked at the wrong data.

Best regards, Sylvain.

3

Thanks for your help.

But My model isn’t working at all. Knee kinetics are not change.

Even I was change my GRF data in the C3d using MoKKa. But Knee kinetics are not change.

In my gait model there is #include “Knee_Kinematics_Output.any” in InverseDynamicModel session. In my opinion maybe i’m using wrong knee kinetic data therefore Knee kinetics are not change.

I’m using AMMRV1.2
Plese check my model.

4

Hi,

There seem to be a problem with the file ForcePlateType2AutoDetection. What happens is that the contact with the foot is not detected, so there is no force transmitted from the plate to the foot. Then of course when you change the force it has no effect because the force is never applied to the foot.

Changing the height and velocity tolerances in the Environment file doesn’t help, so i am not sure yet why the contact is not detected…

Meanwhile my advice is to use the plate without the auto detection: ForcePlateType2. This one will work.

And i have found an error: the gravity vector in the study is not correct. Change it to be on the Z direction.

Best regards, Sylvain.

5

Oh, I missed it.

Thank you, Finally i understood it.

And Knee Kinetics are changing now.