Virtual Marker Trajectories

[Amy Robinson]

Hi,

I am fairly new to OpenSim and I am using it to analyse some cycling data. I have created a virtual marker for my pedal (for which I have no experimental data) and was wondering if there is a way of exporting the trajectory of this virtual marker to analyse without the need for experimental data, given that it has coordinates and is attached to the foot so knows where it is in space and time in relation to my foot segment markers?

Any help or suggestions would be greatly appreciated.

Thank you,

Amy

[Thomas Uchida]

You can use the Inverse Kinematics Tool (open the setup file in a text editor and set the report_marker_locations flag to true).

[Amy Robinson]

Hi,

Yes I have done that. However, because I do not have any experimental data with the pedal marker, it will not let me select this marker when running the inverse kinematics. Is there a way around this?

Thank you,

Amy

[Thomas Uchida]

Yes I have done that. However, because I do not have any experimental data with the pedal marker, it will not let me select this marker when running the inverse kinematics. Is there a way around this?

Could you add junk experimental data (e.g., zeros) for the pedal marker and set the corresponding tracking weight to zero?