Torque-Driven Marker Tracking Problem
Posted: Fri Sep 02, 2022 1:09 pm
Hi all,
I'm working on a project that's similar to the example3DWalking (marker tracking example), but I'm looking to track a sit-to-stand motion. I'm working with a modified version of the Caruthers 2016 model for STS, and I've been able to produce IK/ID results with my model in OpenSim, but haven't been able to get MocoTrack to converge to a solution. Since I can produce IK/ID in OpenSim, I don't think there is an issue with my GRF/marker data files or model scaling process.
The model that I'm using has most of the upper body joints locked (elbow flexion, shoulder flexion etc.), and the lower body joints are not locked. [See fig for visual reference.]. I'm starting with a torque-driven model (like the marker tracking 3D gait example), with coordinate actuators at each of the lower body joint dof's (hip flex, knee flex, etc.). Also, for reference, I have been limiting iterations to 3000 (for time), but can increase this
I have a couple of questions that I'm hoping will help me be able to figure out why my MocoTrack problem is not converging:
1. If joints are locked (like the upper body joints in my model), Moco still treats them as states in the control problem (I believe). [In the .sto file that's produced after 3000 iterations (not converged), I can see my locked joints as columns.] Since my model has a large number (~20 joints) of upper body joints locked, does this significantly slow down the convergence? Is it better to replace these locked joints with weld joints? I'm wondering if my 3000 iterations was too small for this large number of states?
2. If it is fine to leave these joints as locked, should I be adding coordinate actuators to all of the model's joints? (Even if they are locked?) I currently am only adding actuators to the lower body (non-locked joints). (I'm wondering if my model just isn't actuated enough to move?)
Sorry for the lengthy post! Hopefully my explanation makes sense. (Happy to provide clarification or more details about the model/my matlab code, etc. if needed)
Enjoy the long weekend!
Katie Blessinger
Ohio State
I'm working on a project that's similar to the example3DWalking (marker tracking example), but I'm looking to track a sit-to-stand motion. I'm working with a modified version of the Caruthers 2016 model for STS, and I've been able to produce IK/ID results with my model in OpenSim, but haven't been able to get MocoTrack to converge to a solution. Since I can produce IK/ID in OpenSim, I don't think there is an issue with my GRF/marker data files or model scaling process.
The model that I'm using has most of the upper body joints locked (elbow flexion, shoulder flexion etc.), and the lower body joints are not locked. [See fig for visual reference.]. I'm starting with a torque-driven model (like the marker tracking 3D gait example), with coordinate actuators at each of the lower body joint dof's (hip flex, knee flex, etc.). Also, for reference, I have been limiting iterations to 3000 (for time), but can increase this
I have a couple of questions that I'm hoping will help me be able to figure out why my MocoTrack problem is not converging:
1. If joints are locked (like the upper body joints in my model), Moco still treats them as states in the control problem (I believe). [In the .sto file that's produced after 3000 iterations (not converged), I can see my locked joints as columns.] Since my model has a large number (~20 joints) of upper body joints locked, does this significantly slow down the convergence? Is it better to replace these locked joints with weld joints? I'm wondering if my 3000 iterations was too small for this large number of states?
2. If it is fine to leave these joints as locked, should I be adding coordinate actuators to all of the model's joints? (Even if they are locked?) I currently am only adding actuators to the lower body (non-locked joints). (I'm wondering if my model just isn't actuated enough to move?)
Sorry for the lengthy post! Hopefully my explanation makes sense. (Happy to provide clarification or more details about the model/my matlab code, etc. if needed)
Enjoy the long weekend!
Katie Blessinger
Ohio State