DESIGNING A GAS SNIFFER MONITORING SYSTEM FOR A QUADCOPTER

Transcription

1 DESIGNING A GAS SNIFFER MONITORING SYSTEM FOR A QUADCOPTER E. Baterman*, O. Dobzhanskyi* and R Gouws* *North West University, School of Electrical, Electronic and Computer Engineering, Potchefstroom Campus, odobzhanskyi@gmail.com Abstract. Eskom is the leading power supplier in South Africa and safety is one of their biggest concerns. One of these safety concerns are gas leakage in and around power plants. Current systems implemented to detect these gas leakages work very well but there are still some areas where it cannot detect gas leakage. This is where the gas sniffer monitoring system for a quadcopter comes into play. This system is capable of detecting variety of gasses and provides photos, temperatures and GPS readings from where these gasses where detected. The whole system is attached to a quadcopter so that any area of concern can be tested where the current implemented systems cannot. This paper therefore focuses on designing and testing such a system in real conditions. Key words. Monitoring system, gas detection, quadcopter. 1. INTRODUCTION Eskom is the largest producer of electricity in Africa and produces 92% of the electricity used in South Africa being of the top 11 utilities in the word [1]. Safety is one of their biggest concerns and they are always looking for new ways to improve safety in the work place [2]. In the context of this project Eskom aims to reduce the risk involving gas inhalation. Existing current gas detection systems cannot cover all the areas of a power plant. Eskom reduces their safety risks each year, and they reduced the number of employees affected from gas inhalations from two personnel in 2011 to zero in 2012 [3]. This project will therefore assist Eskom by providing information about possible unsafe areas due to high volumes of gas. In the remainder of the paper the following topics are discussed: a background of the current solutions used with proposed solution, then system analysis, functional analysis, system design, system operation, results, and a conclusion. 2. BACKGROUND The following section provides a brief background on the current solutions used for gas detection by Eskom around South Africa and the proposed solution for gas detection. 2.1 Existing solutions to problem Eskom uses many detection systems to monitor hazardous gasses and air quality in and outside power plants since the 1980's. All sites are equipped with SO 2, NO, Ozone (O 3) and Fine Particulate Matter (FPM) monitor systems. This is to ensure a safe working environment and the annual concentrations at all sites within the guidelines set by the DEAT [4]. There are different types of hazardous gasses found in the industry [2], mainly three categories - Asphyxiant, Flammable and Toxic. Each of these gasses reacts differently and has different effects on people. There are mainly two types of gas monitoring systems in place at Eskom today. These systems are: gas monitors outside the power plants at certain areas, and gas monitors inside the power plants. Both of these systems come with their advantages and disadvantages Outdoor Monitoring At Eskom, emission controls need to be done inside and outside the power stations. The current monitoring system installed works effectively but still has its disadvantages and advantages. Table 1 highlights some of these advantages and disadvantages. Table 1: Outdoor monitoring, advantages and disadvantages. Advantages Personnel are notified when hazardous gas is detected in the area. These sites can be accessed from the control room Indoor Monitoring Disadvantages Weather conditions can disrupt the data readings. Only covers the area where the monitors are installed. An indoor gas monitoring system should be able to monitor emissions continuously without interrupt [5]. The indoor monitoring system used by Eskom is manufactured by a company called SICK. This company specializes in sensor development for big industrial companies [4]. Table 2 shows some of the

2 advantages and disadvantages of the indoor monitoring system used by Eskom. Table 2: Indoor monitoring: advantages and disadvantages. Advantages Personnel are notified when hazardous gas is detected in the area. These sites can be accessed from the control room. Extra sensors can easily be added and integrated into the whole monitoring system. Online 24/ Proposed Solution Disadvantages Main circuitry of the system can only be accessed at a specific point. Only covers the area where the monitors are installed. The system can easily be damaged. System is dependent on a constant power supply. To create a system that can monitor gas emissions in a more effective way than the existing solutions cannot, all the shortcomings of existing solutions should be taken into consideration. After all the research done on the gas monitoring system required by Eskom it is clear that there are three main gasses that take place on the factory. These gasses are Sulphur oxide, Nitrogen oxide and Carbon dioxide. Other gas detectors can also be installed but for now these are the gasses to be focusing on [6]. Gas sensors are integrated with a microcontroller mounted onto an existing quadcopter. The remote access of the quadcopter makes it easy to control these gases from a distance and monitor areas with difficult access which makes it to be a perfect solution for the problem. The data from the gas sensors is recorded and the processed data is available to a remote user. What makes this project unique is that it could be used indoors and outdoors, and at different power stations where there are areas of concern. Table 3 represents all the advantages and disadvantages of this proposed solution. Table 2 : Quadcopter monitoring system: advantages and disadvantages. Advantages Disadvantages Covers any area of Weather can affect the concern. readings of the gas detection outdoors. Remote access is The quadcopter has a available. limited power source and will only last a few minutes. Extra sensors can easily The wind thrust produced be added and integrated into the whole monitoring system. This project can be modified to satisfy a wide verity of concerns. The user is able to see exactly what the quadcopter does via video. If gas is detected it is recorded and processed according to Eskom's needs. The exact position is available where gas is detected via GPS readings. by the quadcopters propellers will have an effect on the gas detection. Weather can affect the handling of the quadcopter. 3. SYSTEM ANALYSIS In this section an overview of the whole system analysis is presented as well as the requirement analysis of the proposed solution. 3.1 Requirements Analysis The proposed design solution was done with the following specifications in mind: Access remote areas for monitoring. The system should be able to detect the following gasses: Methane, Butane, LPG, smoke, Natural gas, Carbon Monoxide and Ozone. The monitoring system is able to take pictures of the area where gas is detected as well as GPS can coordinate the temperature for extra safety measurements. The whole system should not be too heavy and should not affect the control of the quadcopter. The system should be able to run for a long time on its power source to collect reliable data. The system should be designed in a way so that future improvements are possible. 3.2 Operational Analysis Figure 1 shows the operational analysis of the whole system. The user will control the software from a PC (I/F 1.0), the control terminal will then collect the data from the monitoring system (I/F 2.0). From there the monitoring system will fit onto the quadcopter where the areas of concern can be monitored and the external interferences will have to be taken into consideration (I/F 4.0).

3 the integrated system is the processing platform (F/U 1), from here all the sensors and communication medium are controlled. The power source will provide constant power to the whole system (F/U 2). There are many sensors used in the system and can be categorized: the gas detection sensors (F/U 3), and all the extra monitoring sensors (F/U 4). This whole system is enclosed in a casing to protect and keep the monitoring system stable. Figure 3 describes all the sub systems in much more detail and it covers its main sections. Figure 1 : Operational architecture. 4. MONITORING SYSTEM FUNCTIONAL ANALYSIS In this section all the separate parts of the monitoring system is looked in detail and described how all the technologies interact with each other. Figure 3 : Monitoring system design. 5. MONITORING SYSTEM DESIGN In this section all the separate sub systems are described in detail as shown in figure 3. All the components from each sub system will also be discussed. 5.1 Processing Platform The processing platform (F/U 1) used for this system is an Arduino Mega It is very small and its processing speed is fast enough (16 MHz) to control all the sensors and communication medium. The Mega has 54 I/O pins making it ideal for the monitoring system which consists of many sensors. Figure 2 : Monitoring system functional architecture. Figure 2 gives a brief overview of how all the technologies interact with each other. The main part of 5.2 Power Source The power source (F/U 2) used for this system is a 2 Cell LiPo battery (XPower 7.4V 2200 mah). This power source is able to provide enough power to power all the components on the system and for the significant time needed. The advantage of using this battery is that after every monitoring session the battery can be recharged.

4 5.3 Gas Detection Sensors The following gas sensors are used to detect the necessary gas. These gas sensors can also be calibrated with a resistor so that the sensitivity of the sensors can be controlled. The higher the value of the resistors the less accurate it becomes; and the lower the value the less sensitivity is achieved. The resistor value used for all the gas sensors is a 12 kω making it reliable and very sensitive to all gasses. The four gas sensors combined will give a very variety of gasses that can be detected as seen from the following: MQ2 - Methane, Butane, LPG, smoke MQ5 - Natural gas, LPG MQ7 - Carbon Monoxide MQ131 - Ozone 5.4 Extra Monitoring Sensors These extra monitoring sensors (F/U 4) make the system much more accurate and reliable for gas detection. Each of these sensors is described to show how they interact with each other and how they make the system more reliable TMP36 Heat sensor With a heat sensor on the monitoring system the temperature of the gas detected can also be given, this will also contribute to making it safer in the workplace GPS Adafruit ver 3.0 Using a GPS it is easy to get the exact coordinates from where the gas is detected TTL JPEG serial interface Using a camera on-board the user can see exactly where and how the gas is detected; each photo captured is stored on the SD card reader on-board of the system Adafruit DS1307 real time clock The real time clock on-board of the system is used to give the exact time and date for when gas is detected, making the system very accurate Micro SD Card Breakout module As stated earlier the SD card is used to store the necessary data that the user cannot access while the system is in use on the quadcopter. 5.5 Xbee Series one The Xbee S1 is used for communication between the user and the monitoring system. These Xbee modules operate at 2.4 GHz and its RF data rate is 250 Kbps and can cover a range of approximately 100 m [7]. These Xbee modules are more than sufficient for the system. 5.6 Software The software used for this project has two sides, the software that is used by the user and the software programmed to control the whole monitoring system on the microcontroller. The software on the user side is a C# application done in Visual Studio and is discussed in detail in the following section. As for the microcontroller a sketch was programmed in C/C++ to control all the sensors and to process all the data before sending it to the user. 6. MONITORING SYSTEM OPERATION In the following section the monitoring software is described, showing all the different options and how the data is presented to the user. From figure 4 it is clear to see that the user has three choices to choose from how the system should monitor the areas around the quadcopter. The three choices are: Monitoring only - The system will continuously collect data from all the sensors, but will not take any photos. Stop Monitoring - Close the connection between user and monitoring system. Photos and monitoring - The system will monitor the area with the gas sensors and when gas is detected the system will take a photo and it will continue in this loop. Photos only - The system will only take photos continuously without stop and without any data from the sensors. It is also clear from figure one how all the data is presented in the program. Figure 4 : User software layout. Figure 5 shows the layout where the gas sensor data will be displayed. The data is represented in two different graphs: one for representing gas and one for

5 the temperature. Each gas can also be shown separately as seen from the figure in the different tabs available. All the data coming from the monitoring system is stored in a database and from there the program displays it in a graph. All the charts data can also be erased when new data wants to be recorded with the "RESET Charts" button. The exact time and date of data to be displayed (shown in figure 4) can also be chosen by the user. When levels of concern are detected the program also let the user know indicating levels from LOW to VERY HIGH. Figure 7 : Integrated system with quadcopter. Figure 5 : Gas and temperature representation via graphs. Each time a gas is detected with a spike in the data readings the program stores all the data from that instance in a text file. The data stored in the text file is the time and date, the name of the image taken, the exact GPS coordinates and the temperature. The format of the text file saved is shown in figure 6. Figure 6 : Text data stored. 7. RESULTS The results of the testing of all the components are given in the following section. Figure 7 shows the integrated system with quadcoper. 7.1 Gas detection Each gas sensor was tested in a short period of time just to show that each sensor reacts to a certain gas being applied to them. All the gas sensors are very sensitive and the spikes shown in figure 8 indicate that each sensor is working effectively. Figure 8 : Sensor affected by gas detection. 7.2 GPS accuracy The GPS used by Adafruit is very accurate and reliable, the only drawback is that the GPS will not function 100% in a closed area inside a building. The GPS also gives the speed in knots and the altitude making it perfect for the use with the quadcopter. Figure 9 shows the accuracy of the GPS with the latitude and longitude compared with a Garmin GPS.

6 GPS coordinates, the temperature of the detected area. It is available for the user to make the whole monitoring system very accurate. 9. REFERENCES [1] Michael R. Carrell, Norbert F. ELbert, Robert C. Hatfield. Human Resource Management in South Africa 3rd edition. London: Thomson, 2006, pp 329 Fig. 9: GPS data reading. 7.4 Power usage The power usage of the whole system can be seen by the following graph shown in Figure 10. It is clear that the four gas sensors draw the most current when in use. The operating time is also given in figure 12, showing that the system with all the sensors can run a maximum time of 2.6 hours. [2] Clitheroe, Moys, Lawrence, Awerbuck. FCS Workshop practice L2. South Africa: Pearson, 2009, pp [3] Fact sheet, Eskom, [online] 2010, Electricity/FactsFigures/Documents/ES _0003EskCommitEnviroRev71.pdf (Accessed : 6 of May 2014). [4] Monitoring and controlling, Sickinsightonline, [online] 2012, /south-africas-largest-electricityproducer-eskom- measures-its-massemissions-rate-with-sick/(accessed : 15 May 2015). [5] Stephen DeFriend, Mark Dejmek, Leisa Porter, Bob Deshotels, Bernt Natvig. "A riskbased approach to flammable gas detector spacing". Journal of Hazardous Materials, vol. 159, pp , October 2007 [6] Emanuel T. Voeltz, Kamini Shah. "Virtual continuous emission monitoring system". Emission monitoring, vol. 5, pp. 1-2, Jan Figure 10 : Power draw of the monitoring system. 7.3 Camera The Serial camera can take pictures in sizes: 640x x240 [7] JIANG Xiao-ling, ZHENG Yu-zheng, ZHANG Xian-chao, MA Yao-yao (School of Communication Engineering, CUIT, Chengdu , China); Program Design of ZigBee Wireless Pressure Gauge [J]; Journal of Chengdu University of Information Technology; CONCLUSION In this paper the design of a gas sniffer monitoring system for a quadcopter was discussed. This system fits onto the quadcopter making the system portable and easy in use. The monitoring system as a whole consists out of a microcontroller, four gas sensors, a camera, SD card reader, real time clock and a heat sensor. It detects a wide variety of different gasses and gives a good graphical representation for the user. The software designed for this system is user friendly. The