Problem by viewing the result of IK

[Dina Sezavar Naderi]

Hello everyone,

I have just solved the inverse Kinematic for my scaled model. The result of scaled model is good and the .mot file is been generated correctly but when I load the motion the model does not move although the motion tool is active. I see that the model is in true (t=0 sec) position after running inverse kinematic and even the model can jump at the position of the end of the movement (t=10 sec) but I do not see a continuously movement between t=0 sec and t=10 sec.
I have attached two photos from the beginning and end of the movement and part of the IK results (.mot file).

Is there any idea how I can solve this problem?

regards

Dina

[Ayman Habib]

Hello,

If you move the slider manually, or advance one frame at a time do you see movement? It's possible that the model is taking to long to render and/or to assemble, resulting in dropped frames so you see only the start/end. You could lower the playback speed to .01 and retry.

Please let us know what you find out,
-Ayman

[Dina Sezavar Naderi]

Hello,

thank you for your reply. Unfortunately I do not see the movement even when I scroll it manually, maybe only for one specific frame. When I Click the play bottun it does not start to play at all even with speed of 0.01 although I see in .mot file that for each frame there is a specific value generated. And at the end when I try to close the model it seems to be hanged and could not be closed. I should close the whole OpenSim software to load another model.

best regards

Dina

[Ayman Habib]

Hi Dina,

For troubleshooting, we need to figure out if this is an issue with your machine, this specific model or the motion that results from IK. I'd perform the following steps:
1. load one of the standard models in the distribution and a premade motion (as in tutorial 1). If that plays smoothly you can rule out the machine being an issue.
2. Assuming item 1 works as expected, try to move the coordinate sliders of your model in the application, to see if the model moves/animates smoothly. Try variety of coordinates. if it fails then it's the model.
3. Assuming 1 & 2 work, you could try to remove the muscles from your model in case muscle wrapping is an issue. It doesn't get exercised by IK but is done for visualization purposes to show muscles. If the motion plays then we identified the issue.
4. If all the above work as expected then likely the issue has to do with the specific motion, I'd file a bug report and attach the model and motion file and we can troubleshoot further. Keep an eye on the messages window or if a red stop button appears in the lower right side of the status bar as that may indicate an error that aborts the visualization altogether.

Hope this helps,
-Ayman

[Dina Sezavar Naderi]

Hi Ayman,

thank you for your tips. You are right, I found a red stop button with the message: "java.lang.ArithmeticException: / by zero". I understand what it means but I do not have an idea what should be corrected to solve this issue.

regards

Dina

[Dina Sezavar Naderi]

Update:

I think the reason of the error message comes from a bug in Opensim 4.4! I repeated the IK by OpenSim 4.3 and it worked perfectly.

regards

Dina