IOT- INTEGRATED ZIGBEE- BASED COAL MINE WORKER SAFETY HELMET

Abstract

Underground coal mining remains one of the most hazardous occupations in the industrial sector. Workers operate for long hours in narrow tunnels where methane, carbon monoxide, dust, heat, and poor ventilation can turn a routine shift into a lifethreatening situation within minutes. Roof falls, gas explosions, and sudden flooding add further risk, and the depth of the workings makes it difficult for surface staff to know the condition of each worker at any given time. This paper presents an IoTintegrated safety helmet for coal mine workers that uses ZigBee wireless communication to report the working environment and the condition of the wearer continuously to a monitoring station. The helmet carries a compact sensing unit built around a low-power microcontroller. A gas sensor measures methane and other combustible gases, a second sensor measures carbon monoxide, and a combined temperature and humidity sensor records the local climate at the working face. An accelerometer detects sudden impacts and falls, a limit switch confirms that the helmet is actually being worn, and a pulse sensor gives an indication of the worker's heart rate. A panic button allows the worker to raise an alarm manually when he feels unwell or notices a hazard that the sensors cannot detect. ZigBee was selected as the communication technology because it consumes very little power, supports mesh networking, and can relay data across a chain of routers placed along the tunnel galleries. Each helmet acts as an end device that sends a short data frame at regular intervals and immediately whenever a threshold is crossed. Router nodes fixed on the tunnel walls pass these frames towards a coordinator installed near the shaft, where a gateway forwards the readings to a cloud database over Wi-Fi or Ethernet. At the surface, a web dashboard displays every worker as a record showing the gas levels, temperature, heart rate, helmet status, and the zone in which the worker was last detected. When a dangerous gas concentration, a fall, or a panic signal is detected, the system raises an audible alarm in the control room and sends SMS and mobile application alerts to the shift supervisor and safety officer. A buzzer and vibration motor on the helmet warn the worker locally so that he can move away from the hazard without waiting for instructions. The proposed helmet aims to shorten the time between the appearance of a hazard and the response of the rescue team. It is designed to be lightweight, battery operated, and inexpensive enough to be issued to every worker rather than only to supervisors.Testing in a simulated tunnel environment showed that alerts reached the surface dashboard within a few seconds of a threshold being crossed. Future work includes adding oxygen sensing, improving underground localisation with additional router nodes, and integrating the helmet with the mine's existing ventilation control system.