Throughout the application we make reference to the various 'Event types' produced by the devices and sensors installed in the vehicles. At the most basic level, an event is some data sent from the device, with an accompanying 'timestamp' (time and date), location, and supporting data or values (such as 'start' or 'end' of the event).
The event types are the 'raw data' on which all of the subsequent functions and analyses are based, and so it is useful to describe how these events are actually measured, and how they are subsequently used.
All events contain a timestamp (date and time, to the nearest second), location data (longitude and latitude), speed (measured from the GPS system), the vehicle identifier and the driver identifier.
The following are the main event types detected and published in the app:
- GPS Report: These are periodic (or turn by turn based) position reports sent from each vehicle.
- Overspeeding: These are 'exception alerts' sent when a vehicle exceeds a given threshold in speed. Our Jackal product sends one report at the start of the overspeeding and one report at the end of the overspeeding. Older Rhinos sends periodic overspeeding alerts during a period of overspeeding, while newer Rhinos will send overspeeding in the same format as the Jackal (start and end).
- Local Overspeeding: For each event, we take the longitude and latitude, and determine what is the corresponding road type (using a road type classification that ranges from residential to highway roads). If the speed of the vehicle is greater than the corresponding speed limit for that road type (as chosen via the local overspeeding settings) then a Local Overspeeding event is created.
- Harsh Acceleration, Braking and Cornering: these correspond exception alerts that are sent when the forward acceleration, backward acceleration (braking) and cornering exceeds certain values. The data is measured using ‘three axis’ accelerometers.
- Engine Status: the Engine Status (on/off) is measured via the ignition wire of the vehicle. Every time the engine status changes from from off to on, or on to off, an Engine Status report is sent from the vehicle. From this we derive various pieces of information about the vehicle, including the amount of time that it is idling (when engine is on but speed is zero) and the length of trips.
- Seatbelt: Each 'GPS report' contains information about whether the driver’s seatbelt is fastened or not, as measured via the seatbelt sensor (which is either a magnetic sensor attached to the buckle, or read out from the vehicle’s built in seatbelt sensor). If the seatbelt is off and the vehicle is in motion (with a speed greater than one defined in the Settings, but usually 10 km/hr) then a Seatbelt alert will be created. NOTE: As discussed in later sections, this means that the total time driven without a seatbelt should be estimated as Number of Seatbelt Alerts x Reporting Period.
- Idling: The idling state is also measured directly by each device, and they can be configured to send information about the total idling time of the vehicle.