wrist model doesn't have mass

[mohamad mahdavian]

Hello. I was trying to do some experiments on wrist model. But i found out that the skeleton parts doesn't have mass. (You can see 0 as mass property in model code).Doesn't it make any problem for estimating muscle forces while doing experiments?!

Best Regards

[Rose Newberry]

Yes, if you try to run an analysis like forward dynamics it won't work without bone mass. I ran into this problem and ended up opening a different model that had mass and copying the values over to the model I was analyzing. If you are using software like SolidWorks to make the geometry files then you should be able to get at least the center of mass from that. Otherwise you'll have to find a way to measure the mass yourself.

[Jonathan Egan]

Hey Rose,

I was trying to use the wrist model (https://simtk.org/home/wrist-model) to perform static optimization but I need to input the mass properties first. Do you have any suggestion as to where I could find a model with the masses, moments of inertia, etc. of the bones?

Thank you,
Jon