Smart Safety Helmet

Project Overview

The Smart Safety Helmet is a worker safety device embedded inside a standard ABS construction helmet. An Arduino UNO monitors an MPU6050 accelerometer for impact events, an MQ-2 sensor for combustible gas and smoke, and a DHT22 for ambient temperature. On detecting a hazard, a SIM800L GSM module immediately sends an SMS alert with the event type to a pre-configured emergency contact number. A buzzer and red LEDs on the helmet's exterior provide local visual and audible warnings.

Key Features & Implementation

• Impact Threshold Detection: The MPU6050's raw accelerometer data is sampled at 200Hz. A peak-detection algorithm flags any acceleration event exceeding 4G in any axis as a potential impact, triggering an emergency alert after a 500ms confirmation window to avoid false positives from normal bumps.
• Dual-Hazard Gas Sensing: The MQ-2 sensor's analogue output is mapped to LPG and smoke concentration levels. Thresholds are set at 300ppm for LPG and 150ppm for smoke — both well below dangerous occupational exposure limits — giving early warnings before conditions become critical.
• GSM Emergency SMS: The SIM800L sends a formatted SMS within 3 seconds of a trigger event containing the hazard type, a severity level, and a "WORKER ALERT" prefix — compatible with any standard mobile number including feature phones used by site supervisors.

Challenges Solved

The SIM800L drew 2A current spikes during GSM transmission, causing the Arduino to reboot from the shared USB supply. Separating it onto a dedicated 3.7V 18650 LiPo cell with a proper voltage regulator and adding a 1000µF bulk capacitor at its supply pins fully resolved all brownout resets during SMS transmission.