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On Body Recording (OBR)

On-body Recording (OBR) allows you to record Motion Capture Data with the Link system anywhere without the need for a laptop or PC by recording directly on the Body Pack. The Body Pack has an internal memory that has the capacity to record up to 15 hours of data. 

1. Set up 

To use On Body recording, it first has to be enabled on the bodypack via MVN.

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1.1 Set up Hardware

1. Connect the Body Pack with the USB-cable PC. 

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2. Turn on the Body Pack.

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1.2 Set up MVN

To configure the Body Pack for On-Body Recording,

1. In MVN go to OBR > Configure On-Body Recording

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2. In the On-Body Recording window enable OBR by pressing the toggle switch. 

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3. You should hear two beeps from the Body Pack and see the Motion Trackers being detected (indicated by the green spheres). The Body Pack is now in OBR mode. 
4. You can set the configurations in this window to your preferences. Once you're done, click Close. 

Name: Used to identify the Body Pack
Suit configuration: Full Body, Lower Body, Upper Body. For MVN Analyze Only: Full Body No Hands, Upper Body No Hands, Lower Body with Sternum.
Scenario: Single Level, Multi Level or No Level. See Scenarios in MVN
Body Dimensions: Fill in the Body dimensions of the person wearing the suit. See Body Dimensions
Props: you can use props in OBR just like in a live session. See the tutorial on Setting up props for MVN Link
Position: GNSS data can be used to get a more accurate outdoor position. See Setting up a Link suit with GNSS and MVN GNSS
OBR Calibration: shows a video of the OBR Calibration. See chapter 2. Calibration and Recording.

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5. Unplug the USB-cable from the Body Pack. You are now ready to start Calibration and Recording.

 

2. Calibration and Recording

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When using On-Body Recording you will not be guided by MVN Analyze/Animate which requires you to perform a calibration before you can actually start recording. You will need to start your recording session with a separate calibration recording. This calibration can be a Npose + Walk (recommended) or Tpose + walk. It is essential to do this calibration recording with care and take time to stand in a proper Npose or Tpose for 5-10 seconds, following by walking back and forth for 5-10 meters. More information on the calibration routines is explained in the Tutorial Video on Calibrating Link and in more detail in the Base article about MVN Calibration.

TIP: If you have a longer OBR session with multiple recordings, it is recommended to perform a few Calibration recordings. This gives more certainty that at least one calibration recording was successful. During the importing of the files, you can select the best calibration file. 

Calibration 
Below the recommended Npose + Walk calibration is described. 
1. Go to the starting spot for calibration and stand in Npose facing the direction you want to walk.
2. Have an operator press the power button on the Body Pack once (short). The Body Pack should beep once, and the LED should start to blink rapidly. 
3. Perform the calibration routine:
- Hold the Npose for 5-10 seconds,
- Relax and walk forward for 5-10 meters
- Make a smooth U-turn
- Walk back to the starting position
- Make a smooth U-turn to face the direction you started in.
- Stand in Npose and hold for 5-10 seconds
4. Have an operator press the power button on the Body Pack once (short). The Body Pack should beep once, go back to solid LED and beep three more times, indicating the recording has ended.

Recording
A recording is done the same as calibration in OBR, but instead of the calibration routine, you perform the Motion Capture session.
1. Stand in the spot you want to start the recording. 
2. Have an operator press the power button on the Body Pack once (short). The Body Pack should beep once, and the LED should start to blink rapidly. 
3. Perform the Motion Capture session 
4. Have an operator press the power button on the Body Pack once (short). The Body Pack should beep once, go back to solid LED and beep three more times, indicating the recording has ended.

 

3. Import Recordings

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Once you are finished with recording, you can import the files.

1. Connect the Body Pack with the USB-cable PC. 

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2. Turn on the Body Pack.

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3. In MVN go to OBR > Import OBR Files (.mtb)

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4. Select where you want to import the data from. Select Bodypack to import the files from the connected Body Pack. 

NOTE: Selecting Local Directory will allow you to select any .mtb files stored on a local drive. 

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5. You can select all the files you want to Import by clicking the checkbox in front of the name. Alternatively, you can select all files at once, by clicking Select All beneath the files box. 

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6. Select the used scenario for the files by selecting it from the drop down menu. 

TIP: By setting the correct scenario before the recording (see chapter 1.2), you can save some time during importing. 

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7. Select which file to use for the calibration and select the performed calibration type (see chapter 2). 

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8. If you did not set up the Body Dimensions during setup, click the "Click to set" button behind the calibration file, to set the Body Dimensions.

TIP: By setting the Body Dimensions before the recording (see chapter 1.2), you can save some time during importing. 

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9. Fill in the correct dimensions, or load a saved Body Dimension file (see this article for more information on Body Dimensions). Press Apply.

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10. Set the output path for the imported files, by clicking the Folder icon next to the Output Path.

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11. Select the Processing type:
- None: Do not process the files and import as .mtb. (note that MVN requires .mvn files for playback, exporting etc.)
- Normal/HD: See this Base article for more information on Processing.

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Additionally, there are the options:
- Delete after Import: Deletes the imported file from the Body Pack after importing.
- Use GNSS Data: If GNSS data was used with the recording, it can be used for positional aiding (more info on GNSS)

12. Click Import to start importing. 

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13. MVN will start importing the files and save them to the setup Output path.

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4. Swap Trackers

The ability to swap tracker strings is available within MVN. The option to do this is found in the OBR tab. Click on the OBR tab, followed by the Swap Trackers window. More information can be found in this Base article on Swap Trackers

 

5. Remote On-Body Recording

Remote On-Body Recording (ROBR) is a hybrid functionality that allows for multiple Body Packs to start a fully synced OBR recording. ROBR does require Wifi to send the start/stop signal to all the Body Packs. More information can be found in this Base article on Remote On-Body Recording.

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