Accelerometer Data in Telematics and Collision Analysis
Introduction
Many commercial Telematics and Insurance Telematics solutions actively capture accelerometer data to generate Driver Behaviour reports and trigger automatic alerts when they detect a possible collision.
The Value of Accelerometer Data
This data plays a crucial role in assessing a vehicle’s activity right up to the collision point, as well as its driving behaviour throughout the journey leading to the incident.
Understanding Accelerometer Sensors
An accelerometer installed in telematics hardware records acceleration and deceleration levels. It measures movement in three directions: forward and backward (X-axis), side to side (Y-axis), and up and down (Z-axis). These measurements are known as XYZ values.
Impact Detection and Driving Behaviour
The accelerometer sensor indicates both the level and direction of any impact during a collision and reveals driving style through acceleration and deceleration patterns. The accuracy depends on securely installing the telematics unit on the vehicle’s chassis, using high-quality sensors, and maintaining a sufficient detection rate.
Measurement Units and Analysis
Accelerometer data typically measures force in milliG. The standard unit, G, equals the acceleration due to gravity at Earth’s surface, which is 9.81 ms-2. In telematics and collision investigations, braking that exceeds 2.5g qualifies as “harsh.” Analysts can convert X and Y axis data into ms-2 to obtain speed values for detailed analysis.
Combining XYZ Values with Location Data
Analysis aims to match XYZ values with location data, creating a comprehensive record of vehicle movement, acceleration, and deceleration. This method helps pinpoint harsh braking events or potential impacts.
Recording Frequency and Data Granularity
The tracking unit determines how frequently it records X, Y, and Z data. Some units log these values only when they record a GPS location, which may occur every 10, 15, or 30 seconds. If a G force greater than 2.5G appears, the system makes an exception and records the event. Not all telematics units use the same criteria for detecting harsh braking or possible impacts. More advanced telematics solutions provide additional data in crash files, capturing second-by-second records for up to 45 seconds before impact and several seconds after, enabling thorough collision analysis.
Role of XYZ Data in Collision Analysis
XYZ data is vital in collision analysis, documenting when deceleration begins—often marking the driver’s initial reaction to an incident—tracking speed leading up to impact, and measuring the collision force.
Estimating G Forces Without XYZ Data
If XYZ data is missing, analysts can still estimate G-forces by examining changes in speed (initial and final velocities), time, and distance travelled, though this method is less accurate than direct XYZ sensor data.
