Crash Detection
Introduction
When an impact or crash occurs, the Munic.Box Crash Detection module instantly identifies the event and alerts your server. This guide explains how to configure the module's parameters and integrate crash notifications into your back-end architecture.
Disclaimer: The primary purpose of this module is solely to detect crashes. Detailed telemetry and crash data can be retrieved via the separate Crash Notification & Buffer module (please contact us for more information).
How It Works
Munic.Box detects impacts using its built-in internal accelerometer. When the Crash Detection module is activated, the device automatically configures the accelerometer to sample at a high frequency of 400 Hz to ensure precise detection.
Accelerometer and GPS data are continuously collected in circular buffers. If an impact exceeds a predefined threshold within a short time window, a crash event is triggered, recording the maximum index of the detected threshold.
To prevent false alarms, Munic.Box only sends a notification to the server if the crash force meets or exceeds a configured Minimum Crash Severity.
Severity Thresholds
The crash severity index is determined by the force of the impact (measured in mg):
| Threshold range | Severity |
| 375 to 625 | 0 |
| 625 to 850 | 1 |
| 850 to 1000 | 2 |
| 1000 to 1250 | 3 |
| 1250 to 1500 | 4 |
| 1500 to 1750 | 5 |
| 1750 to 2000 | 6 |
| 2000 to 3000 | 7 |
| 3000 to 4000 | 8 |
| 4000 to 6000 | 9 |
| 6000 to 8000 | 10 |
| 8000 to 10000 | 11 |
Important Note on Range: The configured range of the accelerometer directly impacts the maximum detectable crash severity. For example, if the accelerometer range is configured to ±2g, the device will only detect crashes up to 4000 mg (a 4g total dynamic range).
Notification Payload
When a valid crash is detected, Munic.Box dispatches a notification containing the following data points:
Crash ID: A unique identifier for the event.
Severity Index: The severity level (0-11) based on the threshold table above.
Time: The exact time of day the crash occurred.
Position: The GPS coordinates of the crash.
Module Configuration
By default, the Crash Detection service is deactivated when linked to your Munic.Box. To enable it, you must apply the following configuration parameters:
| Paramter | Description | Units | Default |
| Module status | Enables or disables the module. | Activated or Deactivated | Deactivated |
| Range of the accelerometer | The operational limits of the sensor. | g | ±2g |
| Minimum crash severity | The minimum severity index required to trigger a notification. | Index | 6 |
Field description
Once a crash is detected and validated against your configuration, Munic.Box sends the data to your server using the following field format:
| Field Name | Description | Format | Size |
| MDI_CRASH_DETECTED | Triggered upon a valid crash detection. Contains the unique ID and severity. | Contains the unique ID and severity. String (crash_id:severity) | 8 Bytes |