Just to add - I have tried translating the center of rotation using the TransformAxis with respect to the prescribed rotational coordinates. The issue here is that there are cases where there are multiple instances of the same rotational value at different times - each with a different translational...

Hi Christopher, So I have been working on developing a spine model with 6 DOF lumbar joints. The kinematic inputs are from experimentally measured data (translation and rotation of joint with respect to time). The kinematics are originally prescribed with respect to time using "prescribed_function"....

Hi all, Does anyone know of a method or function I can used to transform an axis (TransformAxis) with respect to time? I am attempting to translate the center of rotation of a joint, but would like to do it with respect to time if possible (as opposed to a coordinate). I realize I can create a trans...

Hi everyone, Does anyone know how to define the body for which the joint reaction loads are calculated via Matlab (child or parent)? I am trying to use the PropertyHelper but cannot see to access or define what I think is a String Array (apply_on_bodies). When I treat the value as a string value and...

Hi everyone, I was hoping someone could shed some light on this. I am trying to implement an ExpressionBasedBushingForce. The API says that the expressions should be in terms of the bushing deflections theta_x, theta_y, etc. The model successfully loads into OpenSim, but when running static optimiza...

Thank you very much. That seemed to have solved the problem. Was this just a matter of specifying a name in front of "instantiator"? I'm just trying to learn the reasoning behind it.

Ryan

Thanks Christopher, it looks like I did have two versions. For some reason I thought I had been working on the 32-bit but it's actually the 64-bit. My mistake. However, when I compiled the code in CMake using Visual Studio 12 2013 Win64, I then changed everything to x64 in Visual Studio and got the ...

Hi all, I am not too familiar with building user Plug-ins in OpenSim, but I am interested in incorporating a SpineBushing element, which is available on SimTK, into my model. Right now, I am getting a build error in Visual Studio - "LNK1112: module machine type 'x64' conflicts with target machine ty...

After some more reading, it appears that this is likely do to our center of masses being located at the vertebral centers, as opposed to at the joint!

t appears that the disc forces and moments are reported with respect to the ground XYZ coordinates, so the forces in the X and Y direction are effected by the overall orientation of the spine. However, I am still struggling to understand why a flexion extension bushing moment is appearing due to pur...