Xsens

For more information about Xsens, visit the Xsens Website.

Introduction

Xsens uses IMU's to track motion, and exports the segment information in a MVN file. Once the data is processed in Xsens, the data can be exported as a MVNX file. Visual3D can directly read the MVNX file.

This feature was released in Visual3D v5.02.24. If using version 5 to process your data, please follow the instructions here.

Background

Typically, Visual3D reads data in the C3D file format which contains target locations from a motion capture system. Although Xsens can export C3D files, there are reasons why a user may prefer to export Xsens data as an MVNX file. This is explained below.

The target locations are then used to define the POSE (position and orientation) of each segment. One IMU contains the POSE information for one segment. Since Xsens exports the POSE of each segment in the MVNX file, Visual3D can read the MVNX file and use the POSE calculated directly from Xsens.

Another advantage of reading the MVNX format (as opposed to the C3D format) is that the segmental angular velocity and acceleration information obtained from the inertial sensors can be exported in the MVNX file. Visual3D then uses this information in its dynamics calculations, eliminating the need for differentiating the data (which amplifies the noise).

Download Files

• Sample MVNX files
  • These sample MVN files were downloaded from the Xsens Website and then exported from MVN Studio as MVNX files

Exporting Xsens Data

Visual3D reads the MVNX files. To create the MVNX files, you must first collect or load motion data into MVN studio and then export the data MVNX format. It is very important that the MVNX export settings are defined correctly. This is explained in the "Exporting from MVN Studio section" (Step 2).

Exporting from MVN Studio

When exporting the mvnx file from MVNX studio, it is important to export the Position, Orientation, Velocity, Angular Velocity, Acceleration, and Angular Acceleration should be exported. Below are instructions to complete this in MVN Studio.

Exporting from MVN Studio (click to expand)

1. Open MVN Studio

2. Modify the export settings Make sure the following are selected: Position Orientation Velocity Angular Velocity Acceleration Angular Acceleration If any of these signals (translational velocity, translational acceleration, angular velocity, angular acceleration) are missing from the MVNX file, the derivatives of the position data will be used to calculate these signals. NOTE: Once you have set this, these changes will be saved even after MVN Studio is closed. So you only need to do this step once.

3. Load the data

Opening MVNX Files

As of Visual3Dv6, MVNX files can be opened by going to File -> Open in Visual3D.

They can also be opened using the File_Open pipeline command. When the file is opened, the user will be prompted for all the necessary model metrics to create the model.

Processing Xsens Data

Trunk Graphic

The default Xsens model points to the thoraciccerviclet12toacromium_noneck.obj graphic.

This means if the graphic does not appear in your model, you can download the graphic here, unzip the files (obj and mtl), and place them in your default graphics folder. Once the graphic file is placed in the models folder, you may need to close and re-open Visual3D. Instructions to find your models folder can be found here.