Gas Detection

Ficheiros do Projecto

Introduction

  • The aim of the Gas detection project is to enable the existing Wireless Sensor Network with one LCD display that shows messages alerting the users about the danger of the room atmosphere and with a keypad that allows the users to change application parameters on runtime.

Project Overview and Features

The initial set of functional requirements considered for this project follows:

  • Display an alarm message indicating danger when the gas levels rise above a certain limit.
  • Display an informative message indicating the average gas level in the room.
  • Use the keypad to change application parameters on runtime.

In order to implement these requirements, some technical requirements need to be taken in consideration. The main technical requirements identified are the following:

  • The application must not take more than 2 seconds to show the alarm message after the gas level rise is identified.
  • All sensor nodes must send a message to the remote node immediately after the detection of a high amount of gas.
  • The LCD display needs to be powered with 5 Volts DC (the 2 AA batteries of the Motes can’t provide 5 V, the remote node has to be equipped with an extra battery?).

System Architecture

In order to implement the above-mentioned features, the architecture represented in figure 1 is proposed.

RSProject1-Architecture.jpg: 1024x768, 231k (May 21, 2008, at 10:27 AM)
Architecture

The wireless sensor network that is installed inside the Chemistry Lab is assumed to be working properly. The motes collect readings of three different gas concentrations that might be prejudicial to human health:

  • Carbon monoxide (CO)
  • Methane (CH4)
  • Ethanol (C2H5OH)

The WSN uses it’s processing capabilities to cooperatively determine the distribution and related parameters (such as maximum, minimum, average and standard deviation) for the room under observation. The motes installed at each room entrance must use the information collected by the WSN to display relevant information on the LCD panels.

A detailed description of each of the system components follows.

  • Remote Node: The Remote node is responsible for collecting and processing the messages from all nodes in the room.
  • CO Sensor: Measures CO concentration.
  • CH4 Sensor: Measures CH4 concentration.
  • C2H5OH Sensor: Measures C2H5OH concentration.
  • LCD: The LCD, displays alarm messages every time that the gas concentration in the room rises above a certain level, it also shows the actual concentration level of each gas in the room.

Sensor Board Specification

Board Schematics (.pdf)

Board PCB Layout (.pdf)