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Smart wireless shock detection from BeanAir

BeanAir, French wireless sensor networks company, represented in southern Africa by Instrotech, produces a wireless tri-axial accelerometer for shock detection and vibration monitoring for application on trains and transport vehicles, crash and impact testing, ride quality measurement, drop testing, transport monitoring as well as health and usage monitoring systems (HUMS). 

The BeanDevice® AX-3DS integrates an embedded data logger which can be used to log data (up to 1,000,000 records) when the wireless sensor network cannot be reached on a remote site. All data acquired is stored on the embedded flash and then transmitted to the BeanGateway® whenever a Wireless Sensor Network is established.  Scalable measurement range is +6g/+12g/+24g or +2g/+4g/+8g.  Entirely autonomous, the system uses the ultra-low power radio technology IEEE 802.15.4 wireless protocol stack with antenna diversity designed by BeanAir.

While the vast majority of wireless sensors show their limits in harsh industrial environments, BeanDevice® AX-3DS integrates an innovative diversity antenna design which allows the optimisation of radio link quality in environments subject to random and diverse disturbances.  The diversity antenna has been shown to improve both the quality and reliability of a wireless link by an impressive 30%. 

The device integrates smart shock detection technology which detects and recognises a shock event during the ‘sleeping’ or ‘deep-sleeping’ modes.  See Table 1.  This curve shows two shock events, one considered as significant (real alarm) and another considered as not significant (false alarm).

Δd: shock detection hysteresis
Δt: observed duration
If Δt=Δd, the shock event is detected and recognised, the BeanDevice® AX-3DS wakes up and starts data sampling in “streaming mode”.

Several data acquisition modes are available on the BeanDevice® AX-3DS:

  • Low Duty Cycle Data Acquisition mode (LDCDA): the data acquisition is immediately transmitted by radio. The transmission frequency can be configured from 1s to 24h.
  • Alarm Mode: the measured value is transmitted by radio whenever an alarm threshold (fixed by the user) is detected (4 alarms threshold levels High/Low).
  • Survey Mode: operates like the Alarm mode but the device sends a beacon frame frequently informing its current status.
  • Streaming Packet Mode: All measured values are transmitted by packet within a continuous flow at 1000Hz maximum
  • Streaming Mode: all measured values are transmitted in real-time within a continuous flow at 100 samples per second maximum

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