IK tool error

OpenSense enables users to compute the motions of body segments based on inertial measurement unit (IMU) data.
Locked
User avatar
Jocelyn Hafer
Posts: 2
Joined: Tue Oct 22, 2013 6:11 pm

IK tool error

Post by Jocelyn Hafer » Mon Feb 03, 2020 9:22 am

Hello,

I've been working with some gait data collected with APDM Opal v2 sensors and I have gotten through the data conversion and model calibration steps successfully using the Matlab code (I also was able to replicate the output for the example files provided online). With my data, I keep getting what looks like an optimization error when I run the inverse kinematics tool. I've tried testing different sections of my data or shorter data lengths to see if the solver is just getting stuck at a certain data point but the error is always the same (with the same error tolerance).

I've attached a screenshot of the error I'm seeing in Matlab, my original IMU data, setup files, and calibrated model. Any guidance would be greatly appreciated.

Thanks,
Jocelyn
Matlab_IK_error.jpg
error screenshot
Matlab_IK_error.jpg (134.36 KiB) Viewed 408 times
data.zip
data collected using APDM IMUs
(447.47 KiB) Downloaded 51 times

User avatar
Ayman Habib
Posts: 2238
Joined: Fri Apr 01, 2005 12:24 pm

Re: IK tool error

Post by Ayman Habib » Mon Feb 03, 2020 3:42 pm

Hi Jocelyn,

The model you are using (leg39) is planar, so any out of plane motion will cause the solver to fail as you experienced. Please use a model that is capable of matching the orientations specified by your IMU data (or within tolerance).

Hope this helps,
-Ayman

User avatar
Jocelyn Hafer
Posts: 2
Joined: Tue Oct 22, 2013 6:11 pm

Re: IK tool error

Post by Jocelyn Hafer » Wed Feb 05, 2020 12:15 pm

Hi Ayman,

Using a 3D model fixed the issue easily. Thanks!

-Jocelyn

Locked