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Read through our frequently asked questions below
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.
If the problem persists, contact Vicon Support.
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.
To connect Blue Thunder IMU sensors in Vicon Nexus, ensure that:
In Vicon Nexus, if the sensor is unable to connect, an error message will be displayed in the log if:
To clear the Bluetooth cache:
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 Vicon Nexus, Capture.U Desktop, and Capture.U (iOS) will notify you if the firmware is out-of-date.
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 Both Vicon Nexus (2.7-2.9.3) and IMU Research notify you if the firmware is out-of-date.
Unable to connect, Firmware is out of date and needs to be updated.
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:
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:
The sensor axes orientation can be found here:
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:
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.
|Vicon IMU status||LED display|
|Charging||Both LEDs slow blink (50% duty)|
|Charged||Both LEDs on steady|
|Battery Indication||Both LEDs blink 1-4 times, pause; pattern repeats 3 times. For example, full battery – LEDs blink 4 times, pause; pattern repeats 3 times.|
|Sampling||Single or both LEDs brief blink (<10% duty); single or both depending on left or right|
|Bootloader waiting||Single LED on steady|
|Bootloader connected||Both LEDs on steady|
|Bootloader exiting||Both LEDs twinkle|
|Error during a session
||Rapid blinking LEDs|
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.