add a torque actuator in Static Optimization

[Christine Dailey]

I am working with a customized model one legged lower extremity model. This model does not include torso muscles. Therefore, to avoid or fix the "pelvis lilt: constraint violation" I am getting when running SO, I believe I need to add a torque actuator at the lumbar joint as well as to add reserve and residual actuators to the model.

I found the SO tutorial https://simtk-confluence.stanford.edu/d ... timization
and tried using their "strong actuator file" (deleting the left side and the lumbar sections as I only have the right side) however, I'm still getting constraints violation errors.

Do you have any suggestions on how to fix this pelvis lilt: constraint violation ?

Thanks so much!

[Christine Dailey]

Maybe this is easier to answer:
How do I increase the strength or range?

Im getting the following error in SO:

Try increasing the strength and/or range of the following force(s):
semiten_r approaching upper bound of 1
bifemlh_r approaching upper bound of 1
add_long_r approaching upper bound of 1
add_brev_r approaching upper bound of 1
add_mag1_r approaching upper bound of 1

[Dimitar Stanev]

The motion may be demanding and the model may be weak. You can try to use the gait2392 model which has more muscles.

[Christine Dailey]

It does say the model is weak. However, I don't want to add muscles b/c that will make the model more complex. I also only have one force plate so I only want one leg.
So I'm using a customized gait2392 model that only includes the right leg and pelvis. Im not sure how to add muscles..

I was hoping to get advice on how to add reserve and residual actuators and where to place them (coordinate wise). Any thoughts on that?

[Dimitar Stanev]

In general, you don't want to have residuals, thus you should always try to minimize them. As the simple model has less muscles, it is not strong enough to satisfy the motion and forces.

You can start with the gait2392 model and remove the muscles and bodies that correspond the left leg. Then you can repeat the process. I think the reserve actuators are correct. In any case you can also look at the definition of the reserve actuators as provided by the example files in the model folder.

[Christine Dailey]

This is interesting... Maybe if I start with gait2392 model and remove the muscles and bodies that correspond the left leg (as you said) but leave the torso, it could make it stronger.
However, would it solve my problem?
I feel I would still have to add a torque actuator to the left hip to help move the torso. And if that is true, I would be right back where I am now...

Im trying to follow the Static Optimization tutorial https://simtk-confluence.stanford.edu/d ... timization
but apply it to my case.
I tried modified the tutorial's "strong actuator file" by deleting the left side components and the lumbar sections. When the tutorial did this, it solved there "weak model" errors. However, I'm still getting constraints violation errors.