Large knee flexion and large GRF motion (squat)
Posted: Wed Dec 13, 2017 2:46 pm
Hello.
I am Hoon.
I am using the OpenSim with athletic movements to prevent sports injuries and improve performances.
I am currently trying to run RRA and SO with squat exercises using gait 2392 model. In this movement, weights were applied to subject with a weight bar.
So, there are differences compared to walking trials.
1. Ground reaction forces are much larger in this squat exercises than GRFs in walking trials because of barbell's weights.
2. Knee flexion ROM was much larger than walking trials.
I tried to run RRA first. I used the example RRA actuator and task files in the OpenSim-model-2392 directory. After click run, the whole body was moving up-and-down and side-to-side in a view window. I want to know why it happens and how I can keep the position of the body.
After that, I tried to run SO with an inverse kinematics mot file as an input. I used the example CMC actuator file in the OpenSim-model-2392 directory. Although the SO is working, I can see some messages many times during the process. The messages was shown at the time of large knee flexion. Below is that messages.
The model appears too weak for static optimization.
Try increasing the strength and/or range of the following force(s):
semimem_r approaching upper bound of 1
semiten_r approaching upper bound of 1
bifemlh_r approaching upper bound of 1
bifemsh_r approaching upper bound of 1
add_brev_r approaching upper bound of 1
add_mag1_r approaching upper bound of 1
add_mag2_r approaching upper bound of 1
add_mag3_r approaching upper bound of 1
glut_max2_r approaching upper bound of 1
glut_max3_r approaching upper bound of 1
quad_fem_r approaching upper bound of 1
gem_r approaching upper bound of 1
rect_fem_r approaching upper bound of 1
vas_med_r approaching upper bound of 1
vas_int_r approaching upper bound of 1
vas_lat_r approaching upper bound of 1
semimem_l approaching upper bound of 1
semiten_l approaching upper bound of 1
bifemlh_l approaching upper bound of 1
add_brev_l approaching upper bound of 1
add_mag1_l approaching upper bound of 1
add_mag2_l approaching upper bound of 1
add_mag3_l approaching upper bound of 1
pect_l approaching upper bound of 1
glut_max2_l approaching upper bound of 1
glut_max3_l approaching upper bound of 1
quad_fem_l approaching upper bound of 1
gem_l approaching upper bound of 1
rect_fem_l approaching upper bound of 1
vas_med_l approaching upper bound of 1
vas_int_l approaching upper bound of 1
vas_lat_l approaching upper bound of 1
I think I should modify something in actuator or muscle parameter or etc. I am not sure which part I should modify to run RRA and SO correctly for the squat movements.
I looked at the OpenSim documents websites. But I am not fully understanding how and which parts I have to change to run RRA and SO correctly, especially, in squat exercises with weights (large muscle force required and large knee flexion).
In terms of max isometric force for each muscle, I am worried about passive forces change, if I increase the max isometric forces for each muscle in the model.
Any response and advice would be very helpful for me.
Thank you very much for reading my question.
Sincerely,
Hoon Kim
I am Hoon.
I am using the OpenSim with athletic movements to prevent sports injuries and improve performances.
I am currently trying to run RRA and SO with squat exercises using gait 2392 model. In this movement, weights were applied to subject with a weight bar.
So, there are differences compared to walking trials.
1. Ground reaction forces are much larger in this squat exercises than GRFs in walking trials because of barbell's weights.
2. Knee flexion ROM was much larger than walking trials.
I tried to run RRA first. I used the example RRA actuator and task files in the OpenSim-model-2392 directory. After click run, the whole body was moving up-and-down and side-to-side in a view window. I want to know why it happens and how I can keep the position of the body.
After that, I tried to run SO with an inverse kinematics mot file as an input. I used the example CMC actuator file in the OpenSim-model-2392 directory. Although the SO is working, I can see some messages many times during the process. The messages was shown at the time of large knee flexion. Below is that messages.
The model appears too weak for static optimization.
Try increasing the strength and/or range of the following force(s):
semimem_r approaching upper bound of 1
semiten_r approaching upper bound of 1
bifemlh_r approaching upper bound of 1
bifemsh_r approaching upper bound of 1
add_brev_r approaching upper bound of 1
add_mag1_r approaching upper bound of 1
add_mag2_r approaching upper bound of 1
add_mag3_r approaching upper bound of 1
glut_max2_r approaching upper bound of 1
glut_max3_r approaching upper bound of 1
quad_fem_r approaching upper bound of 1
gem_r approaching upper bound of 1
rect_fem_r approaching upper bound of 1
vas_med_r approaching upper bound of 1
vas_int_r approaching upper bound of 1
vas_lat_r approaching upper bound of 1
semimem_l approaching upper bound of 1
semiten_l approaching upper bound of 1
bifemlh_l approaching upper bound of 1
add_brev_l approaching upper bound of 1
add_mag1_l approaching upper bound of 1
add_mag2_l approaching upper bound of 1
add_mag3_l approaching upper bound of 1
pect_l approaching upper bound of 1
glut_max2_l approaching upper bound of 1
glut_max3_l approaching upper bound of 1
quad_fem_l approaching upper bound of 1
gem_l approaching upper bound of 1
rect_fem_l approaching upper bound of 1
vas_med_l approaching upper bound of 1
vas_int_l approaching upper bound of 1
vas_lat_l approaching upper bound of 1
I think I should modify something in actuator or muscle parameter or etc. I am not sure which part I should modify to run RRA and SO correctly for the squat movements.
I looked at the OpenSim documents websites. But I am not fully understanding how and which parts I have to change to run RRA and SO correctly, especially, in squat exercises with weights (large muscle force required and large knee flexion).
In terms of max isometric force for each muscle, I am worried about passive forces change, if I increase the max isometric forces for each muscle in the model.
Any response and advice would be very helpful for me.
Thank you very much for reading my question.
Sincerely,
Hoon Kim