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Possibilities of the Accelerometer in Simple Hardware Devices

The accelerometer is a mechanical sensor that measures acceleration in the three axis X, Y, Z. In our firmware, the supported range is from -2G to 2G (the only exception being the Don't drop me mode and its WiFi-enabled variants) - the data from the sensor can be reported (and indeed is when using some user modes).

Accelerometer and magnetometer axis orientation

Both the accelerometer and the magnetometer have their axis defined from factory, which means that the way they are assembled also has an effect on the orientation of the sensors.

You can find the orientation of both sensors below.

Accelerometer and magnetometer orientation

Things the accelerometer can report

  1. Any movement in general (Guard me, Track me, Monitor me, Put me back modes, this includes anything from tracking goods to monitoring object vibration)

  2. Orientation (via appended payload, Put me back mode) or orientation max values (Put me back) or tilt (a simple threshold event measuring degrees and reporting a breach of preset orientation)

  3. Rapid acceleration/bang/fall (Don't drop me mode - rapid acceleration in one of the axis, the trigger of the message can be set in three ways and both time and acceleration threshold can be adjusted)

The sensitivity of the sensor is by default the same in all three axis, but can be customized so you can have e.g. Z axis more sensitive than the other two.

Monitoring vibration


A quick note on monitoring vibration; if you need to monitor both normal vibration (e.g. engine running) and odd vibration (e.g. engine malfunctioning), this is possible to do by combining regular accelerometer events (such as Guard me or Track me mode) with rapid acceleration detection (Don't drop me), however, this has to be very finely calibrated and there are situations where this would not work (where the vibration is just too similar for the device to pick it up).

The standard way of monitoring vibration occurence with Monitor me mode is binary (vibration detected/not detected) and the data is reported in time intervals (e.g. vibration occured in 68% of the last four minutes). Monitor me also reports data in a pipeline which allows you to save the battery whereas the combination of regular accelerometer-based events and rapid acceleration reports doesn't support a pipeline.

To get a grasp on how the accelerometer can be used to monitor vibration, please read our blog post on how we monitored that the fridge in our office is working properly right here.