Although the system is developed using verification from field data, national crash tests and data published in research, detecting accidents can be an ill-posed problem. Large vehicles, with thin shells, and varying suspension quality, will experience changes in velocity that may be impossible to separate from harsh driving on bad roads. The system should be used with caution and an understanding of the practicalities of accident detection.
Note: Accident detection and reconstruction is disabled by default. It needs to be enabled and tuned to a specific vehicle type
The accelerometer is used in an advanced accident detection system. The accelerometer is orientated to forward/back, left/right, up/down regardless of the installation using GPS data and movement. After installation, this takes about 15 minutes of normal driving.
The accident detection system does the following:
- Accidents are detected using 2D (horizontal) changes in velocity over 120ms. The change threshold is configurable in the settings below.
- Roll overs are reported when the vehicle’s angle to the “normal” horizontal plane exceeds 60 degrees.
- Drop detection detects velocity changes in the vertical dimension.
Device Installation and Auto-Orientation
For more information on this, please see this support article. Note that only basic accident detection is available while the system is calibrating itself (no rollover or vertical filtering).
Second by second GPS data is saved into a section of the device's flash memory. There is capacity for about 2 hours of data. In the event of an accident, a subset of the data is uploaded to the server to allow a detailed reconstruction of the incident. 60 seconds before and 10 seconds after the incident will be uploaded. The upload is done in specific accident data fields in flexi records.
An upload can also be requested by an async message to the device. The start and end periods for the upload can be specified. If no records exist for that period, the upload will be empty.
The data is currently saved by the OEM server. Contact support to find out about retrieving it. There are also options to send the data to software platforms via OEM.
Point data can be retreived in a CSV export and map data in an HTML map file. See this explanation.
The following device types and firmware version support accident detection and reconstruction:
- G60: firmware version 1.40 and later
- G100: firmware version 1.9 and later
- Dart: firmware version 1.6 and later
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System Parameter Setup
- Accident Logging allows 3 levels of logging.
- Off (default): results in no detection and automatic upload of reconstruction data. Reconstruction data can still be requested by an async message.
- Accident Log Reason: logs only the accident record and no reconstruction data.
- Accident Log Reason & Reconstruction Data: logs the accident record and reconstruction data.
- Accident Delta-V Threshold is the magnitude of the change in 2D velocity over 120ms that will trigger an accident. The units are km/h. The default is 7km/h. This corresponds to 1.6G over the 120ms period.
- Disable Orientation allows the advanced accelerometer features (roll detection, driver profiling, and drop detection) to be disabled.
- Disable Vertical Accident Filtering allows the drop notification to be disabled.
- Wakeup Threshold and Wakeup Count relate to the accelerometer's sensitivity to movement that will wake the device up or keep it awake. Generally, the defaults of 1 and 0 respectively should be used.