How to get the kinematic information of any marked point through opensim

[wuhaohao wuhaoaho]

Hello, I'd like to ask how to build a set of marked points under any human model, and then get the kinematic information (position, velocity, acceleration) of these marked points through one of the analysis tools?

[Thomas Uchida]

I think you're looking for the PointKinematics Analysis (https://simtk.org/api_docs/opensim/api_ ... atics.html).

[wuhaohao wuhaoaho]

Thank you very much for your answer. The link you replied to is the source code of point kinematics, I'm sorry, because my programming ability is limited, I can't understand it, How to use the PointKinematics tool in opensim?

[Thomas Uchida]

The PointKinematics Analysis is used in a similar way as the other analyses. Please refer to the following pages in the User's Guide:
- "Getting Started with Analyses": https://simtk-confluence.stanford.edu/d ... h+Analyses
- "How to Use the Analysis Tool": https://simtk-confluence.stanford.edu/d ... lysis+Tool

Here is a brief description for the PointKinematics Analysis specifically, using the arm26 model as an example:
- open the model
- select "Analyze" from the Tools menu
- provide a motion or states file (e.g., ...\Arm26\OutputReference\InverseKinematics\arm26_InverseKinematics.mot)
- in the "Analyses" tab, click "Add" and then "PointKinematics"
- "PointKinematics" will now appear in the list; select it and click "Edit"
- if you want to compute the position, velocity, and acceleration of the "r_radius_styloid" marker, for example, note that its parent body is "r_ulna_radius_hand" and it is located at (-0.0011 -0.23559 0.0943) on this body -- so set "body_name" to "r_ulna_radius_hand", set "relative_to_body_name" to "ground" (assuming you want to compute the position, velocity, and acceleration of the marker relative to the global or "ground" frame), and set the three coordinates of the "point" ([0], [1], and [2]) to -0.0011, -0.23559, and 0.0943, respectively
- run the analysis and plot the results from the generated files

[wuhaohao wuhaoaho]

Thank you for your answer, here can realize the point kinematics analysis of each required mark point, can I get the kinematics information of multiple mark points?

[Alexandra Dunning]

Hi Thomas, do you know how to get the coordinates (x,y,z) to input into the 3 positions in the point kinematics tool? Thanks