We provide sensor straps of various sizes for attaching sensors to the upper and lower limbs. Sensors can also be strapped to the body using physiotherapy strapping tape, and can still maintain a wireless connection when taped within an athlete’s strapping.

Blue Thunder

• • Make sure you have downloaded and installed all the required drivers (https://www.silabs.com/products/development-tools/software/usb-to-uart-bridge-vcp-drivers) when using Lighting to download data.
  • If your sensors are still not recognised, unplug your sensors, turn them off and on, then plug them in again.

If the problem persists, contact Vicon Support.

Blue Trident

• • The data you collect is unfiltered and transparent. This allows you to utilize the most appropriate filtering techniques for deriving the metrics you want.
  • However, if you capture to sensor and choose to output the aligned data, this will temporally align all sensor data and upsample the lower frequencies using linear interpolation to match the highest frequency axis.

Blue Thunder

• • The data you collect is unfiltered and transparent. This allows you to utilize the most appropriate filtering techniques for deriving the metrics you want.

The sensors collect at different sampling rates because the crystals used in the sensor circuitry are not perfectly identical to one another.  These crystals control the measurement frequency.  Thus, each sensor measures at slightly different sampling rates (e.g. 999.99 Hz vs 1000.01 Hz).  We use time syncing to help with these small differences.  This is also why there will not be an equal number of data points in each log per sensor.

• Blue Trident
  • The Low-g accelerometer saturates at ±16g (±156.9 m/s/s) in each axis
  • The High-g accelerometer saturates at ±200g (±1961.3 m/s/s) in each axis

• Blue Thunder
  • The accelerometer saturates at ±16g (±156.9 m/s/s) in each axis.

To connect Blue Thunder IMU sensors in Vicon Nexus, ensure that:

• • The operating system is Windows 10 (64-bit)
  • Nexus 2.7 – Nexus 2.9.3
  • The sensors are connected to the Bluetooth® in Microsoft Bluetooth & other devices

In Vicon Nexus, if the sensor is unable to connect, an error message will be displayed in the log if:

• • you have previously paired the IMU sensor with another PC,
  • the sensor firmware is out-of-date,
  • have recently updated the sensor firmware,

To clear the Bluetooth cache:

1. In Microsoft Bluetooth & other devices, select the IMU sensor and remove the device.
2. Open Lightning Desktop
   DOWNLOAD LIGHTNING
3. On the first time of using the application, download the CP210x USB to UART Bridge VCP Drivers:
   DOWNLOAD DRIVERS
4. Turn on the IMU sensor and plug in via USB.
   Note that only two sensors can be connected at one time.
   The IMU sensor number is displayed.
5. Select Clear Bluetooth and then select Clear all devices.
   This clears the Bluetooth cache on the IMU sensor.
6. Reconnect the IMU sensor in Microsoft Bluetooth.
7. Open Vicon Nexus and connect the IMU sensor.
   The sensor is connected.

Blue Trident

The latest Blue Trident IMU sensor firmware is available via the Capure.U Desktop app.  Vicon Nexus, Capture.U Desktop, and Capture.U (iOS) will notify you if the firmware is out-of-date.

• • Blue Trident firmware is updated through the Capture.U Desktop app.

Blue Thunder

The latest Blue Thunder IMU sensor firmware is available via the IMU Research app. Both Vicon Nexus (2.7-2.9.3) and IMU Research notify you if the firmware is out-of-date.

• • In Vicon Nexus, after connecting your sensor, the following error message is displayed in the log:

Unable to connect, Firmware is out of date and needs to be updated.

• • In the IMU Research app, on the Select Sensors window, the IMU is displayed with a warning symbol in the middle of the sensor. This indicates that the firmware is out-of-date and needs updating.

Blue Trident

• • To update the Blue Trident sensor firmware you will use Vicon Capture.U Desktop. Capture.U Desktop will indicate a firmware update is required when the sensors are connected. For more details please refer to Update sensor firmware

Blue Thunder

• • To update the firmware for an IMU sensor, you must use the IMU Research app (iOS):

1. If there is no session in IMU Research, create a session. To do this, tap the + in the top right of the app, then name the Session and tap Done.
2. Tap the session.
3. Select New Trial, name the trial and then tap Start Capture.
4. Ensure the IMU sensor is turned on.
   The sensor is displayed under Select Sensors with a warning symbol in the middle of the sensor.
5. Select the sensor you want to update.
   A message is displayed: Firmware Update Required.
6. Tap Update.
   During the firmware update, do not close the app or shut down the device until completion.
   Upon completion, a message is displayed: Firmware Update Complete.
7. Tap OK.

If, when you select Transfer Files for the IMU sensor, the progress bar does not change, ensure the CP210x USB to UART Bridge VCP Drivers have been installed. Download the drivers from:

DOWNLOAD DRIVERS

With Nexus closed, install the drivers and restart the PC.

Launch Nexus, attach the sensor and re-try the IMU data transfer.

We have identified an incompatibility problem when using Lightning with Windows 10 1903 release (March, 2019).

The problem (hang) occurs when the “File Open” dialog is displayed, for selecting Sync files, Download location, etc.

The fix is to enable Compatibility Mode for Lightning:

1. Right-click the Lightning application shortcut and click Properties.
2. Go to Compatibility tab, then check the box next to Run this program in compatibility mode for: 
3. Select Windows 8 to use for Lightning in the drop-down box.
4. Click Apply and OK to save the change.

The sensor axes orientation can be found here:

Blue Trident

• Attach the straps to the subject, ensuring that:
  • The strap sits snugly against the limb
  • The sensor is oriented with the top (head) pointing in the same direction as the movement of the subject.
  • The flashing LED is at the top of the strap.

The following example shows a strap attached so that the sensor sits directly on the medial aspect of the tibia, just above the medial malleolus:

Blue Thunder

• Best practice for sensor placement is what we call the “man-up” position.
  • The black half of the sensor is closest to the body, with orange facing out.
  • The IMU Man is standing up, with the on/off switch pointing down.
  • It is useful employing this method as it helps knowing sensor orientation when interpreting your data during analysis.

Blue Trident

• • Nexus 2.10 or above
  • Minimum of iOS 11 and Bluetooth Low Energy (BLE) 4.2 for Capture.U 1.1
  • To access AR Visualization capture mode, Vicon recommends an iOS 13 device, BLE 5 and an Apple A12 Bionic or above chip device
  • For more information see Capture.U app requirements

Blue Thunder

• • Nexus 2.7 – Nexus 2.9.3
  • Any iOS device released since 2014 using the IMeasureU Research app

• • Minimum of iOS 11 and Bluetooth Low Energy (BLE) 4.2 for Capture.U 1.1
  • To access AR Visualization capture mode, Vicon recommends an iOS 13 device, BLE 5 and an Apple A12 Bionic or above chip device
  • For more information and a table of compatible devices see Capture.U app requirements

• • iOS 13, Bluetooth 5, and Apple A12 Bionic (or above) chip devices
  • For more information and a table of compatible devices see Capture.U app requirements

• • High = 1920 x 1080
  • Medium = 480 x 360
  • Low = 192 x 144

• The following requirements are the minimum that are recommended and fully supported:
  • Capture.U Desktop for Windows
    • Windows 10 (64-bit)
  • Capture.U Desktop for OSX
    • MacOS Sierra (10.12)

The Vicon Capture.U App is iOS only and we have no current plans to develop it for Android. The Vicon Capture.U App has been designed to work with both phones and tablets. Apple provides greater consistency in their operating system for phones and tablets, whereas there is more variation with Android, which would require multiple versions of the app to be supported on a variety of devices.

The sensors are synchronized by radio beacon, broadcast from one sensor. This synchronization occurs at the start of the recording session and requires that all sensors be within radio range of each other (<10m). Once synchronization is complete, all sensor clocks will be aligned within 100us, and no additional synchronization occurs.  From this point, each sensor will “dead-reckon” based on their own high-accuracy clocks, and do not need to stay within radio range. While dead-reckoning, each sensor clock will drift at a low rate, affected by manufacturing variation and temperature difference, relative to each other.  Assuming the sensors operate at a similar temperature, the expected drift is less than 20ms per hour.

Dead-reckoning used in a temporal sense. The key concept is that the sync occurs once only, and from this point the timebases of each sensor will drift apart from each other.

There is no sync mechanism. Both video and sensor streaming are free running and produce frames as fast as possible. In all capture modes, there may be a lag in data frames (a small offset) between sensors when starting capture, but the data will by synced.

When a trial is started within the Capture.U app, it initializes each sensor one at a time. Once a sensor is initialized, it immediately begins recording for that trial. Similarly, when a trial is terminated, each sensor is terminated individually.

When multiple sensors are collected in a trial, the sensor which was initialized last is used to set time 0 based on its first time stamp. All sensors are then re-sampled using linear interpolation and values for time 0 are extracted for each sensor. Subsequent values for all sensors are then output based on the user-selected Output Rate (hz) with its end frame dependent on when the sensor terminated in the app.