High-G event detection is supported on a select group of Digital Matter devices. High-G events can be enabled in the Accelerometer Settings tab on OEM server:
|Oyster||1.6 and above|
|Remora||1.35 and above|
Because High-G detection requires the accelerometer to run at a higher speed than usual (100 Hz, versus the usual 12.5 Hz), it is disabled by default. This saves a small amount of battery:
|State||Current||Alkaline Battery / Year|
(Periodic Only tracking, High-G events disabled)
|0 uA||0 %|
|Accelerometer On @ 12.5 Hz|
(Normal tracking, High-G events disabled)
|6 uA||0.75 %|
|Accelerometer On @ 100 Hz|
(High-G events enabled)
|24 uA||3 %|
When enabled, the accelerometer will detect High-G events exceeding the specified force and duration, and log a record containing:
- Log reason 'High-G Event' (46)
- The current time (record time)
- The last known GPS time and position (field 0)
- The peak force seen (FID 24)
- The average force seen (FID 24)
- The duration of the event (FID 24)
Since the immediate record contains only the last known GPS position, the High-G Event Action can be configured to attempt a GPS fix after each High-G event. It can also be told to attempt to upload the result of the fix once, or to continue retrying the fix/upload until they succeed, with increasing back-off timeouts in the event of failure.
In addition to requiring additional battery power for the accelerometer, High-G events use battery when responding to each event. The device must wake up whenever it sees a large force, and verify that the force meets the criteria for logging.
Because the accelerometer is sensitive to gravity, it wakes up more easily when experiencing vertical forces. However, gravity is not considered when evaluating the criteria for logging. This filters out nuisance events from speed bumps, but might in extreme circumstances allow many High-G event wake-ups to go unnoticed, as they did not lead to a logged event.
When using High-G detection in situations prone to repetitive vertical forces (for instance, on corrugated roads, or with continually vibrating machinery) be sure to set the force threshold high enough to avoid repetitive wake-ups, and the associated battery use.
The default threshold of 2Gs is suitable for regular vehicle tracking, where continuous vertical forces are not expected. To determine the minimum safe threshold in challenging environments:
- Set the High-G Event Force threshold to its minimum value (1.5 G @ 10 ms)
- Test the device in its intended application
- If the detector doesn't go off, a threshold of at least 2.6 G is safe
- If it does go off repeatedly, add at least 1.1 G to the reported peak force
High G Alerts and Reports in Telematics Guru
To start tracking and reporting on High G events in Telematics Guru you'll need to set up an Alert, an Event to have it show on the Trip History view and be able to run the Custom Event Report.
Setting up the Event
The event is the first step for setting up the High G Event reporting. An Event is simply a function that you can feed data into from an Alert, thus they are very simple.
In Telematics Guru, Go to Admin > Event Types and click the New button to the right and you'll see the setup box as below with the required settings.
There are other logging options, but for an instantaneous High-G event - they do not make sense to configure. The above will return the time and location of any High-G event in our reports - which is what we want.
Setting up the Alert
See how to set up an alert step by step here.
As usual, ensure to give the alert a Name and message in the General Tab. Apply it to the relevant assets in the Assets Tab, and select who we should send the alert to under Notifications. Then the other specifics for this feature are:
In the Conditions tab, select 'Use Device Data log Reason' and select High G Event from the list that's populated.
In the Advanced tab, you'll need to set the Event type that you made in the previous step. Then click Save
Trip History View
On the trip history view, you can quickly identify where High G Events have occurred by the Alert icon as shown below. The Trips with these events on them are also marked in the trip list for each day.
The Asset Timeline history view, shows the events also, and you can click the magnifying glass on the trip entry to see where on the map the location of the event.
Running the Custom Event Report
In Reports > All Reports, you can select the Custom Events- Detail or Summary to view the occurrences of the High G Events with a variety of filters including Assets, Asset Types, drivers with the date range as a parameter.
Peak-G, Average-G and Duration
In Telematics Guru, these values are reported in the following Analogue Fields:
- Analogue 18:
- Peak G-Force
- Analogue 19:
- Average G-Force
- Analogue 20:
- Duration of the event
They can be viewed in the device telemetry Assets -> Telemetry