Motion detection Engine:
The motion engine two-stage filter mechanism determines if the device is moving or
stationary, the purpose of this two-stage filter is to be able to filter out both short spurious
unintended accelerometer interrupts and filter out slightly longer period of stop or start such
as when an asset stops moving for short period of time due to an obstruction on route.
Motion Engine.
The first stage filter is a Coarse filter to filter out the odd unintended accelerometer
interrupts such as when a heavy item is dropped adjacent to the device. This can be seen as
a short time-based filter on detected acceleration. The second stage filter is the Fine Filter to
filter out short periods of motion start.
3.1 Coarse Filter
The Coarse filter takes accelerometer interrupts as an input and as an output, will set the
device state into either Active or Inactive, which are the two inputs for the further Fine filter.
The Coarse Filter uses the following configurable variables:
• Motion Threshold
• Activity Window (Seconds)
• Activity Threshold (Seconds)
The accelerometer generates an interrupt when it senses movement, this interrupt is the
trigger for activity and occurs when the detected acceleration events are over the Motion
Threshold (OTA programable Accelerometer threshold 0-10, where 0 is off and 10 is most
sensitive). The accelerometer is configured to generate a maximum of 1 interrupt per
second.
For the device to be set into Active state, the device needs to detect more interrupts than the
Activity threshold during the configurable Activity Window.
Active state is True when the number of interrupts > Activity Threshold during Activity
Window.
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