RRA with knee adduction

[Peter Martindale]

I have been using the running simulation model developed by Hamner, SR. to develop a pipeline for analyzing gait and have got RRA to run with good residuals (using the timeframe for when the right foot is in contact with the force plate in my grf data).
I am interested in studying the knee adduction moment so I adapted the model code to include (limited) adduction coordinates for both knees and similarly adapted the task, actuator and control constraints files used previously.
When running the RRA tool in the same timeframe, the right tibia adducts greatly and the tool crashes. I have tried both increasing the tracking weights and increasing the maximum excitation for the residuals, as suggested in the troubleshooting in the userguide but the problem persists.
Has anyone else tried adding extra degrees of freedom to a model and had this problem?

[Yusuke Okita]

Hi, Peter

I suppose the additional tasks or actuators for RRA have not been successfully incorporated in your analysis.
I would suggest you verify if the additional actuator which abducts the right knee and the tasks which define how the additional actuators track the prescribed data are correctly described. I would also like to know if you used the IK data which contains the time course of knee ab/adduction angles. If not, you might run RRA without the information of knee adduction angles. I'm sorry if you have already done these things.

Yusuke

[Peter Martindale]

Hi Yusuke,

Thank you for the reply. I think I now have the problem sorted and it was due to a mistake by me in the actuator file that I had previously missed. I had added the actuators into the file but I had assigned them to the knee flex-ext angles rather than adduction.

Thanks again,
Peter

[Pouya Amiri]

Hi Peter,

I need a model with knee adduction angle. I do not think that there is any available model in open sim which has adduction angle. I am new to opensim and do not exactly know how I can add a DOF in frontal plane. Would you help me please?

Thanks.
Pouya