Jostle Mode: Benefits and Applications of Accelerometers in Tracking
A key feature critical to tracking is the ability to effectively detect the start and endpoints of a trip, while still conserving valuable battery life.
By default, battery-powered devices such as the Remora2, Oyster2 and Falcon can track trips in the following ways:
‘Standard’ GPS Tracking Mode
Accelerometer wakes unit
On each wake, it gets a GPS fix
It tries to figure out if it is in trip by looking at the fixes
Once it thinks it’s moving, it enters a trip
Once in-trip, the accelerometer is turned off
It wakes up every few minutes on a timer and gets a fix
It checks if the trip is still in progress by looking at the fix
When the fixes suggest movement has stopped, it exits the trip (if the device can’t get a fix for a while, it also exits the trip)
Uploading can happen before, during, and after the trip, optionally
Heartbeats happen if there has been no upload for a long time
This method ensures that the GPS is used sparingly, preserving battery life. Standard Tracking also ensures that trips only begin when the device has moved some distance from its original position. In contrast, our range of battery-powered devices can also be configured for Jostle Based Tracking, with operation as follows.
‘Jostle Based’ Tracking
Accelerometer wakes unit
The unit immediately enters trip
Once in trip, the accelerometer no longer wakes the unit
It wakes every two minutes on a timer, and does two things:
Asks the accelerometer if there was any movement in the last two minutes
If it is time to log a position, it gets a fix and records it
Once the accelerometer claims there has been no movement for a while, and the GPS doesn’t show movement, the trip ends
The trip can continue even if the GPS isn’t showing movement, so long as the accelerometer is
Uploading can happen before, during, and after the trip, optionally
Heartbeats happen if there has been no upload for a long time
The purpose of this is to allow trips to be recognized regardless of the size of the motion
It is much less robust than GPS tracking mode at rejecting false trips – so only useful for things like run hours, or tracking tiny trips
Benefits and Applications of Jostle Mode
Run Hour Tracking – A device can be attached to a stationary object such as a pump or generator. When vibration is detected, it will enter a trip. The start and end time of this trip can be used to calculate the run hours of the asset.
Rapid Movement Alerts – Rather than waiting for a device to be moved some distance, an upload can be triggered immediately once a device detects accelerometer movement. By default, there is some filtering to prevent even tiny nudges from starting a trip – but this can be disabled, allowing a notification on the slightest nudge – meaning you can get alerts fast.
Tracking Small Movements Within a Yard – Small movements within a yard cannot be reliably detected using traditional GPS tracking methods. The use of the wake filter ensures even small movements will cause the position of your asset to be updated on the server, so you can find it when required.
Conserve Battery Life – If false trips are unlikely to be an issue – i.e. your device shouldn’t vibrate unless it is truly on the move – the use of Jostle Mode means the device does not have to spend time and energy checking the GPS for movement when it gets going, increasing your battery life.
