VRfree® Tracker Manual

VRfree® Omni-directional / Single-directional Tracker

The following guide and manual relates to the VRfree® Tracker, build 2021. 

VRfree® system package contents:

  • 1 VRfree® Headmodule, to be fastened to the headset or to a stationary position.
  • 1 VRfree® Tracker 
  • 1 NB-8L batteries, within the Headmodule (please remove the battery from the Headmodule)
  • 3 cables (below the interior carton): 1 long USB-C to USB-A for the Headmodule, 1 short USB-C to USB-A cable for the Wristmodule, 1 short USB-C to USB-C cable to connect the Headmodule to the HTC Vive/Vive Pro/Focus or the Oculus Quest.

Before you get started - charge batteries

Please remove the battery from the Headmodule. You will not need it unless you use the system in a standalone mode (untethered, with a Quest or a Focus). 

Re-charge the Tracker by connecting it to a USB-power source via its USB-C socket.

List of features

VRfree® Headmodule

  1. Frequency / Status LED: Indicates what frequency your Headmodule is on. Your VRfree Headmodule can communicate with the Wristmodules on one of 7 different pre-set frequencies, each represented by a different colour. Make sure that your Head- and Wristmodule run on the same frequency ie colour when powered on. You can cycle through these preset frequencies by pushing the button repeatedly.
  2. Frequency selection: Select one of 7 different pre-set frequencies, each represented by a different colour. You can cycle through these preset frequencies by pushing the button repeatedly.
  3. USB-C slot: Plug-in the USB-C cable connection to your PC or mobile HMD.
  4. Charge-enable button: Only relevant if you connect your Headmodule to a mobile HMD such as Oculus Quest 1/2, Vive Focus 1, 2, 3 or similar. The button allows you to choose whether the Headmodule battery draws power (gets charged) from the mobile HMD or not.
  5. Power button: powers on your VRfree® Headmodule.
  6. Battery lid: keeps your 3.7V, 700mAh, 2.6Wh rechargeable battery in place.

List of features

VRfree® Tracker

  1. Power button: This power on your Tracker.
  2. Frequency selection button: Select one of 7 different pre-set frequencies, each represented by a different colour. You can cycle through these preset frequencies by pushing the button repeatedly.
  3. Free programmable button: This button can be programmed to perform a function of your liking. Please refer to the Unity Script for more details.
  4. Frequency / Status LED: Indicates what frequency your Tracker is on. Your VRfree Tracker can communicate with the Headmodule on one of 7 different pre-set frequencies, each represented by a different colour. Make sure that your Headmodule and your Tracker run on the same frequency ie colour when powered on. You can cycle through these preset frequencies by pushing the button repeatedly.
  5. USB-C socket: Plug-in your USB-C cable here to calibrate the Tracker or to charge its battery.
  6. Tracking beacon: To verify that your VRfree® Tracker is connected to the VRfree® Headmodule on the right frequency hold the opening close to your ear while the Headmodule and Tracker are powered on. If you can hear crackling noise the Tracker is correctly connected.
  1. Mount the Headmodule on your HMD using the velcro pad (Videolink).
  1. Connect the long USB-C cable to the Headmodule and your PC (Videolink). If you have a HTC Vive or Vive Pro, use the short USB-C cable to connect the VRfree® Headmodule to the extra USB-socket of the Vive (the signal is fed through to the PC).
  1. Power on the Headmodule. The Frequency and Status LEDs should light up.

Register your tracker with the system:

  1. Download the VRfree® Setup (here) if you haven't already done so.
  2. Connect your Tracker to your PC using the provided USB-A to USB-C cable.
  3. Switch on your Tracker by pressing the Power button (1).
  4. Open the VRfree® Setup menu and click on "Device Configuration": see here.
    • Within the "Device Configuration" menu click on the upper dropdown menu
    • Select a Tracker ID of your liking. Memorize or write down the number. Usually each tracker comes already preconfigured, so this step should not be necessary. 
    • Disconnect the Tracker
  5. Connect your Headmodule to your PC using the provided USB-A to USB-C cable.
  6. Switch on your Headmodule by pressing the Power button.
  7. Open the VRfree® Setup menu and again click on "Device Configuration": see here.
    • Within the "Device Configuration" menu, check the two fields "Enable Rotation" and "Enable Position" next to the Tracker ID that you chose earlier in Step 4: see here
    • Press "Save Configuration"
    • Disconnect the Tracker
  8. Perform a "Tracker Orientation Calibration": see here. Please follow the calibration steps shown in the videos. 
  9. With that your Tracker is registered with your Headmodule and can communicate with your system.

IMPORTANT: The more devices you register per headmodule, the lower the update frequency of any single one device! You can see that in the "Device Configuration" menu: When operating 6 trackers plus 2 gloves the "distance measurement frequency" drops from 50Hz to 12.5Hz. For best performance you should therefore only have those devices registered in the "Device Configuration" that you really need for that specific task / simulation!

VRfree® Headmodule - Hardware Calibration

  1. Please download the VRfree setup zip on the V2 Download Page, extract and run it (Videolink).
  2. If you haven't already done so, attach your VRfree® Headmodule to your headset and connect it via the long USB-C to USB-A cable (for the HTC Vive/Pro use the short USB-C to USB-C cable as illustrated here).
  3. Now run the VRfree setup program.
  4. Select "Head Module IMU Calibration" from the Menu (Videolink).
  5. Follow the steps in the VRfree® Headmodule IMU Calibration Video on the left or use this Youtube link

Testing your Tracker in the VRfree® Setup Scene

  1. Make sure your Headmodule and your Tracker are switched on and communicate on the same frequency (LED colour). To check you can hold the tracker to your ear. If you hear a faint crackling sound then the Tracker is communicating with the Headmodule.
    Now, within the VRfree Setup please select the "Handpose calibration". Put on your headset and test the accuracy of your Tracker's position and orientation.  

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