ID: ERROR - mass matrix is singular
Posted: Sun May 23, 2010 11:51 pm
Hello,
I am performing an inverse dynamics simulation with the Stanford upperlimb model. When I load my .mot file I get the error "InverseDynamics: ERROR - mass matrix is singular".
My ideas for the possible cause of the error are the following:
1 - I made an artificial mot file (artificial in the sense that it was not produced by inverse kinematics using real marker data) which smoothly moves the arm into different poses, with little pauses at each pose. Perhaps when at each pose, since the coordinates do not move at all, could this be interpreted as an error??
2 - I have only specified mass and inertia properties for some bodies, not all of them. If the inverse dynamics tries to then use an empty mass/inertia matrix, would this cause issues??
Or perhaps there could be another issue I am not thinking of. In any case, can you please let me know which is likely to be the cause of the error, and what steps I can take to get around it?
Thank you
Marc
I am performing an inverse dynamics simulation with the Stanford upperlimb model. When I load my .mot file I get the error "InverseDynamics: ERROR - mass matrix is singular".
My ideas for the possible cause of the error are the following:
1 - I made an artificial mot file (artificial in the sense that it was not produced by inverse kinematics using real marker data) which smoothly moves the arm into different poses, with little pauses at each pose. Perhaps when at each pose, since the coordinates do not move at all, could this be interpreted as an error??
2 - I have only specified mass and inertia properties for some bodies, not all of them. If the inverse dynamics tries to then use an empty mass/inertia matrix, would this cause issues??
Or perhaps there could be another issue I am not thinking of. In any case, can you please let me know which is likely to be the cause of the error, and what steps I can take to get around it?
Thank you
Marc