Determining IK of model without trc file?

[Pa G]

Hi all,
I am a student and doing my project work here, i don't have any experimental marker data (.trc )file. Still is it possible to determine the Inverse Kinematics / Inverse dynamics of the model (to which i attached robot)? If so please give me information about it.

And my 2nd query is ,how to plot movement of the eg: elbow joint, in the space w.r.t time?

Thanking You
Pav G

[Thomas Uchida]

i don't have any experimental marker data (.trc )file. Still is it possible to determine the Inverse Kinematics

Yes, you could potentially design and run an inverse kinematics algorithm that computes skeletal joint angles given some other type of experimental data (e.g., video).

how to plot movement of the eg: elbow joint, in the space w.r.t time?

Please see the "Plotting" section in the Confluence documentation (https://simtk-confluence.stanford.edu/d ... m/Plotting).

[bao wendy]

you could potentially design and run an inverse kinematics algorithm that computes skeletal joint angles given some other type of experimental data (e.g., video).
Could youn please give me a simple example or explain in more detail?

[Thomas Uchida]

Could youn please give me a simple example or explain in more detail?

The Inverse Kinematics Tool in OpenSim can be used to compute skeletal kinematics from experimental marker trajectories. My interpretation of the original question was whether it is possible to compute skeletal kinematics without marker data. Yes: there are techniques that use other types of measurements (e.g., http://kidzinski.com/project/kinemai/).

[Pa G]

Thanks Thomas, but neither video be converted to .trc file nor that application (that you mentioned) is available to download. Any suggestions please.
And Why IK needs to compare experimental data with virtual markers? Just it's virtual motion (.sto) doesn't enough?

[Thomas Uchida]

Why IK needs to compare experimental data with virtual markers? Just it's virtual motion (.sto) doesn't enough?

It isn't clear what data you have and what you're trying to compute. From your initial post, it sounds like you performed an experiment in which a human was interacting with a robot but you didn't collect marker data. How did you generate the .sto file? If the file contains the trajectories of the model's coordinates, then you do not need to run Inverse Kinematics---but it may depend on which model you are using, what you are trying to compute, etc. I recommend looking at the tutorials and examples (https://simtk-confluence.stanford.edu/d ... +Tutorials) and description of the OpenSim Tools (https://simtk-confluence.stanford.edu/d ... +and+Tools) to get a sense of what is possible and formulate a plan.

[bao wendy]

Thanks Thomas,what puzzled me is that i want to analy joint load in static sitting posture, then i don't have any experimental marker data(.trc)file, i only have the position and trajectory of the center of the joint and the curve of joint angle with time, is it ok to analy joint angle load at the last frame?if ok,what tool can i use ?