Link length

[Rahid Zaman]

Hi,
I am Rahid. I am using Rajagopal full body model for my project. I need to do the scaling manually. But, to do this I need to know the link length or bone length of generic opnesim model, in my case Rajagopal full body model. How can I know the bone or link length of a generic model so that I can compare the measurement with my laboratory model?

Thanks in advance.

[Thomas Uchida]

How can I know the bone or link length of a generic model so that I can compare the measurement with my laboratory model?

One method is to look at the locations of the joints, which are defined relative to the origin of the parent body. For example, in the arm26 model, the "r_elbow" joint's parent_body property is "r_humerus" and its location_in_parent property is "0.0061 -0.2904 -0.0123"—thus, the humerus is about 29 cm long. These properties can be obtained from the Properties window in the GUI or by opening the OSIM file in a text editor. Another strategy in this example would be to add markers to the model at the ends of the humerus and get their locations in Ground.

[Rahid Zaman]

Thank you very much for your reply. I finally able to do the scaling. It is working just like as I wanted. I plotted the GRF also.

But, I only have joint angles (.mot) and GRF(.mot) files. Is it possible to do the CMC in anyway using this two files ? I do not have any marker file as I generated the motion using programming.

Thanks in advance.

[Thomas Uchida]

But, I only have joint angles (.mot) and GRF(.mot) files. Is it possible to do the CMC in anyway using this two files ? I do not have any marker file as I generated the motion using programming.

CMC does not require marker trajectories. You should be able to use the kinematics you've computed, provided the file is in the correct format. Please see the following pages in the Confluence documentation:
- "Getting Started with CMC" (https://simtk-confluence.stanford.edu:8 ... d+with+CMC)
- "Storage (.sto) Files" (https://simtk-confluence.stanford.edu:8 ... o%29+Files)
You can also refer to the example files in your OpenSim installation directory (e.g., C:\OpenSim 3.3\Models\Gait10dof18musc\OutputReference).