Plug-in-gait_Simple - missing three initial steps

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1

Hi Everyone,

I am currently working on the Plug-in-Gait_Simple to perform gait calculations with personal C3D files.

I can’t figure out why calculations start with a delay, no matter the C3D file I am using: my first obtained value is 0,015s even if my actual first step is 0s (with a 0,005s loadstep, I should get also 0,005s and 0,010s).
When checking in “Main.ModelSetup.C3DFileData.Header.FirstFrameNo” value is 1, which is correct, but it should correspond to 0s and not 0,015s.

In TrialSpecificData_FullBody.any, I tried to manually input the first and last frames but It did not solve my problem.

Thank you in advance for your advices,

2

Hi So_Any

Yes. I see why this may be confusing. he InverseDynamic Analysis will start with 2 frame delay compared to your mocap file. This necessary because the solver needs to calculate some velocities and accelerations numerically, and therefore needs to perturb variables. The default is to use +/-2 frames.

The configuration of this delay happens in this file:

You can try to change it and see what happens, but I would suggest you just start you mocap file 2 frames earlier if this is important to you.

Bw

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I don’t understand about code error.
I run inverse not complete.

4

Hi melund3,

Thank you for your message and your accurate explanation.

I managed to start the InverseDynamics at the first frame (actually there is a one step delay compared to the C3D file but the last frame is also delayed by one step, so I guess that is not a problem).

But hence, what about the quality of the calculation and the results ?

5

Hi chamannii

I will give you a quick reply here, but if you have more questions please create a new thread.

The actual error is on this line:


ERROR(OBJ.DES3) :   D:/../InverseDynamics.any(50)  :   LoadParametersOptimizationResults  :  Design initialization :  Failed loading design values from file. The file could not be opened for reading.

This indicates that the file ("…/Input/FullBody-lifting5kg-OptimizedParameters.txt") could not be found. Most likely you didn’t run the parameter optimization step of the model which generates that file.

/Morten

6

Hi So_Any

I managed to start the InverseDynamics at the first frame (actually there is a one step delay compared to the C3D file but the last frame is also delayed by one step, so I guess that is not a problem).

Ok. That tells me that you are probably not using the lastest AMMR 2.1. Is that correct. The newest version should start two frames later and end two frames before. The number of steps should also be reduced by exactly 4 frames.

But hence, what about the quality of the calculation and the results ?

I am not sure what you mean. Are you afraid it will affect accuracy or?

Bw
Morten

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