How to deal with low contact force of hip joint in swing phase

Main Forum
1

Hi,
My model results of hip contact force is much lower than experiment data.just like the figure shows below. The swing phase load decreased drastically. SO does someone know how to correct the model to solve this problem?
many thanks.
Thomas.

2

Dear Thomas,

There are many factors that could result in this mismatch. Could you be more specific about your simulation? At this point I presume that you used a MoCap model using Motion Capture data that you acquired yourself as well as the hip joint reaction force? Are you trying to compare a matching dataset (#1)? Secondly, it could be an error in the C3D file - for example, the force plate data is not recorded properly in the swing phase and, thus, result in the lack of hip reaction force (#2). It could also be due to the muscle activation criterion selection (#3). Natural difference between the AnyBody generic model and the subject in the experiment (#4). And many more…

Could you describe your model a little more? With the information that you provided it could be many things. My colleagues might have something else to add, but it would also help them to know a little more.

Kind regards,
Pavel

3

Dear Pavel,
First, my data comes from online database(HIP98) of hip joint.It contains the kinematics of human, experimental results of joint reaction force, and many more…
Second, I constructed a subject-specific model(based on GaitVaughan model) and used the kinematics(Hip flexion, abduction, internal/external rotation,knee flexion…) and ground reaction force and positions to drive the model, not C3D.
Finally, the muscle recuitment criteria is polynomial, power2. I have simulated all the criteria, finding P2 is best.
So I can’t find any problems in other aspects of model, except the unfamiliar part—muscle properties(Simple muscle in my model). Now can you help check it?
Many thanks.
Thomas

4

That helps a little. Could you please check and maybe post here the force plate data here around the swing phase? Could it be that there are some recorded values when the toe is already off the ground?

Pavel

5

This is the ground reaction force data here. As you know, the first column is the time, and another three are x,y,z component force.
Thanks.
Thomas.

6

Hi Thomas,

Please try to change the txt file so that the loads applied when there is no contact is really zero and not something else, this might help ?

Next step would be to run the model with no muscles and check that the loads of joints muscles are resonable.

Another simple thing to check is if gravity is applied ok?

Best regards
Søren

7

Dear Søren,
many thanks.
Thomas.