problem with knee joint loads too high in result of Inverse Dynamics

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Dimitar Stanev
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Joined: Fri Jan 31, 2014 5:14 am

Re: problem with knee joint loads too high in result of Inverse Dynamics

Post by Dimitar Stanev » Tue Jun 06, 2017 2:58 pm

You can also check whether the kinematics' .sto file is in deg or in rad and if the header is specified correctly.

Best

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Linjie Wang
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Joined: Wed Sep 30, 2015 1:06 am

Re: problem with knee joint loads too high in result of Inverse Dynamics

Post by Linjie Wang » Wed Jun 07, 2017 5:40 am

Thanks, Dimitar.

The problem was caused by petallar ligments which jointed the calculation during the inverse dynamics. And its scale factor of force magnitude decides how much force would be produced on the knee joint acting like an external load.

Thanks,
Linjie

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Jack Zhao
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Joined: Thu Jul 24, 2014 7:15 am

Re: problem with knee joint loads too high in result of Inverse Dynamics

Post by Jack Zhao » Wed Jan 03, 2018 7:15 am

wanglj6chris wrote:Thanks, Dimitar.

The problem was caused by petallar ligments which jointed the calculation during the inverse dynamics. And its scale factor of force magnitude decides how much force would be produced on the knee joint acting like an external load.

Thanks,
Linjie

Dear Dr Wang:
I am a PhD graduate from Hong Kong Polytechnic University, and you can call me Jack. My direction is also closely related with the lower limb analysis with comprehensive muscles and ligaments. More specifically, it is "Exploration on lower limb muscle recruitment pattern".
Excuse me for the disturbance. I saw your post here, and it seems that you have found the reason why the JW model from 4th grand competition generated huge moments when taking the ligaments into account. Actually I am also focusing on the model with the other left leg mirrored by the pelvis symmetry plane. The major ligaments on the hip, knee and ankle joints were also developed based on the 4th JW model. However, when performing ID analysis, the results are similar, although much lower than those you posted on the forum (still 400~600Nm in terms of the knee moment, and similar cases happen to other degrees of freedom).

It would be much appreciated if you can share some of the experiences on the reason underlying the results, i.e. as you mentioned, the ligaments participate in the ID calculation in the same way as the measured GRF ?

If you wish, maybe we can also communicate through the email. My email is zilong.zhao@connect.polyu.hk
I can also share the development of the lower limb model if needed and we can test altogether. Looking forward to our further discussion and cooperation.

Best regards
Jack Zhao

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