The IMU Placer (available as of OpenSim 4.2) provides an interface to associate and register each IMU sensor with a body segment of an OpenSim model (as an IMU Frame). This is a basic calibration routine in which the first time step of IMU data is registered to the default pose of the model.

To launch the IMU Placer Tool, select Tools → IMU Placer from the OpenSim main menu bar.

Overview

Inputs and outputs of the IMU Placer tool. The file names here are used from the example distributed with the GUI and can be found in Models/Rajagopal_OpenSense.

Inputs

Input files:

1. Model file (e.g., Rajagopal2015_opensense.osim): An OpenSim model on which the IMUs will be placed.
2. Orientation file at placement pose (e.g., placement_orientations.sto): Experimental orientations, represented with quaternions, used for placing IMUs on the model at the default pose. Only the first frame of the file is used.
3. Settings file (e.g., imuPlacer.xml): A file containing all the settings information for the IMU Placer tool.

Other settings:

1. Data transformation: Space fixed Euler angles (XYZ order) from IMU space to OpenSim
2. IMU Placement/Heading Correction (Optional): Specify optional arguments to correct or adjust for the overall difference in the heading (forward direction) of the IMU data versus that of the OpenSim model. Typically, an OpenSim model is facing in the positive X direction of the ground Frame in the initial pose, but the base IMU (e.g., on the pelvis or torso) can have any initial heading

Outputs

1. Output model (e.g., walking_orientations.mot): OpenSim model with IMUs placed.