REAL-TIME, WSN FEATURE, AIR QUALITY MEASUREMENT, CONTROL AUTOMATION AND CHEMICAL HAZARD AND FIRE WARNING SYSTEM

TECHNICAL FIELD

The invention relates to a system that provides electronic circuits, control software, hardware (firmware) software, sensor reading/evaluation methods and the calculation of the air quality index (AIR, Air Quality Index) necessary to measure, evaluate, store and report air quality parameters, to provide remote data communication, to communicate with WSN sensors, to detect harmful chemicals and fires, and to activate sound and light alarm mechanisms for warning purposes.

PRIOR ART

Air pollution continues to be an environmental problem for the whole world. According to the World Health Organization (WHO), around four million people worldwide die every year due to air pollution. The Air Quality Index (AQI) is used to measure air quality. If the air quality values recommended by WHO are reached, a decrease of approximately 15% is expected in all deaths. This means protecting the lives of more than 600 thousand people by an approximate calculation. In a determination made by WHO, it is stated that if the concentration of PM (Particulate Matter) increases by 10 pg/m ³ per year, it may cause a 6% increase in the total mortality rate; and that if an increase of 10 pg/m ³ is in question for a few days, it may cause cough, lower respiratory tract symptoms, an increase in the number of hospital admissions and death. In recent studies, it has been one of the most emphasized issues due to the negative health effects caused by PM2.5 and even PM1 and PM0.1 instead of PM10. It has been revealed that air pollution is an important environmental problem that threatens public health, as well as an important factor in the increase in the number of cases and deaths due to COVID-19. It has been determined that every 10 pg/m ³ NO2 and PM2.5 increase increases the number of cases by 7% and 2%, and every 1 pg/m ³ PM2.5 increase increases the death rates by up to 15%.

After the WHO's declaration of the pandemic, many studies were conducted on transmission routes and precautions. Scientists, who claimed that the virus could be transmitted by air and could remain in the air even if the source person left the environment, and their suggestions were not taken into account by WHO for a long time. The manifesto for WHO, written by 239 scientists from 32 countries in July 2020, is titled "It's Time to Talk About the Air Transmission of COVID-19!" . The text reads: “There is significant potential for infection risk if virus-laden micro-droplets are inhaled over short and medium distances. We advocate the need for preventive measures to mitigate airborne transmission. We are concerned that the lack of recognition of the risk of airborne transmission of COVID-19 and the lack of clear recommendations on airborne virus control measures will have significant consequences. People may feel protected when they follow current recommendations. In reality, however, additional airborne interventions are needed to further reduce the risk of infection. This issue will become even more important as people return to their workplaces and students return to schools and universities in countries. Provide adequate and effective ventilation, especially in public buildings, workplace environments, schools, hospitals and nursing homes to reduce the risk of airborne transmission; bring clean outdoor air, minimize circulating air.”

The fact that the effect of epicdemic still continued to increase after the first year of the it is over, its and the contamination examples showing that the virus can be acquired "depending on the duration of stay in closed, crowded areas" has led scientists to agree on the importance of ambient ventilation. WHO could not remain silent on these calls and published a guide titled “Roadmap to improve and provide indoor ventilation in the context of COVID-19”. Based on the finding that “providing adequate ventilation can reduce the risk of COVID-19 infection”, the guideline stated that ventilation is not just about “opening the windows” but “if the outdoor air contains a high concentration of particulate matter, the outside air may need to be treated (filtered) before it is distributed inside the building”.

People spend most of their time indoors. After a while, air pollution occurs in indoor areas such as homes, workplaces, shopping malls, cafes, and restaurants. This pollution can sometimes become much more dangerous than outside environments. For this reason, indoor air quality should be paid attention to indoors and it should be checked regularly whether the inhaled air is healthy.

Carbon dioxide gas is a colourless and odourless non-toxic gas with a mass of about 1.5 times the air we breathe. However, in environments where it is present in high amounts, it can have a suffocating effect by reducing the oxygen level of the air. In humid environments, it may react with water to form a sharp odour. The amount of CO2 released into the atmosphere due to oil, natural gas and coal used to meet the energy needs of human beings continues to increase day by day. For this reason, the amount of carbon dioxide in our environments is of great importance.

Indoor air quality is a value that describes how good or bad the air we breathe in indoor environments is. According to the researches, the value of indoor air quality directly affects the happiness and determination of the employees in the workplaces and the learning desires of the students. For this reason, more and more private companies and public institutions are doing the necessary work to provide indoor air quality in their buildings. According to the researches, poor indoor air quality causes the employees to be adversely affected in 30% of office environments.

All objects and people inside buildings emit a volatile organic (VCO). Smoke circulating in the ventilation systems in the buildings, drugs released or sprayed to the environment for pest cleaning, sealed glasses, cleaning materials, tools such as photocopiers and printers in offices, sinks are the reasons that most affect the quality of the air in the environment.

Since the amount of CO2 in our environment affects the indoor air quality, it reduces the indoor air quality. This low indoor air quality causes many negative situations. The leading results of these negative situations are short-term, but often redness of the throat, watery eyes, headaches, weakness, persistent feeling of tiredness, and severe airborne diseases. Apart from diseases, polluted air causes loss of learning and production and high health expenditures.

In order to learn the indoor air quality of your environment, first of all, it is necessary to measure the air quality in the environment. For this, there are measuring devices with which you can monitor the indoor air quality.

The following measurements are made in indoor air quality measurement;

• If there is a HVAC system, CO2 measurement, Humidity measurement

• If there is filtration, PM 2.5 measurement, Humidity measurement

• If disinfection is used, PM 2.5 measurement, O3 measurement, NO2 measurement, Formaldehyde measurement

• If Portable Air Purifier is used, Fresh air delivery rate, PM 2.5 measurement, O3 measurement, NO2 measurement, Formaldehyde measurement Building related syndrome: Building-related illnesses (BRIs) are factors related to the indoor environment of the building. These can only be resolved by eliminating their source. They are not factors that can be solved by ventilation. For example; Legionnaires' disease. We can solve this disease by limiting the living environment of the bacteria. Bacteria and fungi created by the humidity in the building can be given as examples.

Sick building syndrome: They differ in building-related illnesses because their disturbances are not easily recognized and cannot be easily eliminated. SBS typically presents with acute disturbances, such as fatigue, headache, blood withdrawal, and optic nerve. These disturbances may pass when the building is abandoned. It is not possible to diagnose these disorders. The causative agents of SBS are very variable. Overheating, noise, poor lighting can cause them. There are also psychological factors that cause these symptoms. For example, overcrowding, architectural and decoration-related disturbances. When designing a space, architects have to do everything from the number of people to the lighting, in accordance with the standards.

Table 1 gives information about the disorders related to the syndromes.

Table 1. Air quality symptoms

Indoor Air Quality Parameters: We can examine the factors affecting indoor air quality in four main categories.

Biological Factors: Bacteria, viruses, fungi, molds, pollen, animal hair are among the most common biological pollutants that adversely affect air quality.

Chemical Factors: cleaning agents, solvents, fuels, adhesives, combustion byproducts, floor and wall covering materials are among the most common chemical contaminants.

Particles and Aerosols: They are solid and liquid substances that are light enough to hang in the air. Particles can be classified into three categories: Coarse, fine, very fine. The finer the particle size, the greater the risk of adverse health effects. The formation of particles can be caused by dust generating activities, printing and photocopying processes, manufacturing processes, smoking, combustion processes and some chemical reactions.

Physical Factors: temperature, humidity, air circulation and air flow rate can be counted among the most basic physical factors.

While air quality was seen as a major health problem for people before the pandemic, today it has become a bigger health problem with the pandemic. While factors such as outdoor air quality were emphasized in the past, today it is emphasized that indoor air quality is as important as outdoor air quality. There are many established measurement stations in the world for the measurement of outdoor air quality established for this purpose. In addition, global warming can bring atmospheric disasters, and according to a common view, it is said that with the melting of glaciers, viruses, bacteria and microbes that today's people, who have been in the ice for a long time, can mix with water/air, and this can cause different pandemics.

In a study conducted in the USA in 2005, NASA researchers managed to revive a bacterium found in a frozen pond in Alaska for 32,000 years. It has been observed that this bacterium, which belongs to the period when furry mammoths lived, continued its life as if nothing had happened after the ice was thawed. Two years later, an 8-million-year-old bacterium, frozen under glaciers in Antarctica, was brought back to life. In the same study, bacteria found in 100 thousand-year-old ice were also animated. In a study conducted in Siberia in 2014, two 30 thousand-year- old viruses (Pithovirus sibericum and Mollivirus sibericum belonging to the giant viruses class) found at a depth of 30 meters were animated. Prof Jean-Michel Claverie, who is involved in the project and works at the National Scientific Research Center of the University of Aix-Marseille in France said “This is the first time we have seen that a virus found after such a long time is still contagious” on the subject. Looking at these and similar developments, it is understood that encountering new endemics/pandemics is a near possibility. Many researches and studies have been conducted on the relationship between air pollution and endemic/pandemic:

1. It has been demonstrated that patients with severe Covid-19 infections requiring intensive care are twice as likely to have pre-existing diseases, particularly heart disease, stroke, chronic lung diseases and diabetes, due to air pollution.

2. 120 cities in China were analysed and after controlling for all factors, it was revealed that there is a significant relationship between air pollution and COVID-19 infection.

3. In the five years before the pandemic, places with higher levels of nitrogen dioxide pollution (10 micrograms per cubic meter) had 22% more cases of Covid-19, while higher levels of small particle pollution saw a 15% increase in infection.

4. It has been demonstrated that particulate matter pollution is positively associated with increased cases of COVID-19.

5. Air pollution has been found to be positively associated with higher mortality rates from COVID-19. It has been demonstrated that NO2 concentration is positively correlated with the transmission ability of COVID-19. The UK Office for National Statistics has found that long-term exposure to fine particulate matter, without checking for ethnicity, can increase the risk of contracting and dying from COVID-19 by up to 7%. In the Netherlands, a municipality with 1 pg/m ³ higher concentration of PM2.5 will have 9.4 times more cases of COVID-19, 3 times more hospital admissions and 2.3 times more deaths. It found that 78% of coronavirus deaths in 66 administrative regions in Italy, Spain, France and Germany occurred in just five regions, with these being the most polluted. High mortality rates in northern Italy have been found to be associated with the highest levels of air pollution. lt has been found that air pollution levels in the UK are associated with COVID-19 cases and deaths. While investigating whether the coronavirus could be carried over longer distances and increase the number of people infected, coronavirus was detected on air pollution particles. lt has been found that higher levels of particulate pollution may explain the higher infection rates in parts of northern Italy before the quarantine was implemented. The rapid spread of COVID-19 in northern Italy has been found to be strongly associated with air pollution. It has been found that increased exposure to hazardous air pollutants (HAPs) is associated with a 9% increase in COVID-19 mortality. An association was found between an 11 % increase in mortality from COVID- 19 infection and exposure to air pollution over many years for every 1 microgram/cubic meter increase in air pollution. People living in communities with longer exposure to exhaust gas emissions have been shown to have higher mortality rates from COVID-19, and it was reevaled that, when there is a 4.6 ppb increase in NO2 exposure (mainly from city traffic), case fatality rates increased by 11 % after controlling for other factors that could increase the risk of dying from the disease. 18. lt has been found that annual exposure to nitrogen dioxide (a pollutant from exhaust pipe emissions) in neighbourhoods of the City of Los Angeles is associated with the incidence and mortality of COVID-19, with an 8.7 ppb increase in NO2 leading to a 35-60% increase in mortality.

19. It found that there were approximately 20,000 extra coronavirus infections and 750 deaths associated with exposure to high PM2.5 levels from the 2020 wildfires in 92 western US states.

20. It has been found that someone living in a highly polluted area of China is twice as likely to die from SARS than someone living in an area with clean air.

21 . During the SARS epidemic in 2003, increases in particulate matter air pollution were found to increase the risk of dying from the disease.

22. Researchers have suggested that many viruses, including adenovirus and influenza virus, can be carried on air particles. Particulate matter has been found to most likely contribute to the spread of the 2015 avian flu.

23. It has been demonstrated that air pollution can accelerate the spread of respiratory infections.

As can be understood from the studies mentioned above, there is an important relationship between air pollution and diseases. This relationship is in the form of the formation of chronic diseases, the increase in deaths due to chronic diseases, and it is understood that air pollution increases the rates of admission to intensive care and death due to the pandemic, especially when the Covid-19 pandemic we live today is taken into account. Indoor air quality also has a significant impact on the spread of Covid-19. In order to minimize the spread, it is necessary to have a healthy and high quality air indoors.

Within the scope of the project, considering current pandemic conditions and future pandemics, measuring indoor air quality, regulating it through automation systems, creating audible and light warnings, designing, producing, and transforming these systems into industrial products that can be used for indoors with domestic resources and domestic technology for the development of smart sensor systems with many different capabilities and capabilities, as well as chemicals and fire warning systems will play an important role in the present and future of our country.

As long as people do not stop breathing, they will always need quality and clean air.

The system designed on the basis of eliminating the above-mentioned negativities: It is designed as an automation control unit that will enable the installation of communication units and relay cards that will be used to store the values obtained by measuring the indoor air quality (IAQ I) in the area where it is installed or installed as mobile, to prepare reports, to control air quality systems.

Indoor air quality measurement processes are mostly periodic or one-time measurements performed by measurement service companies. The service provider prepares a report by evaluating the environment by taking hourly measurements with its accredited devices.

Two types of air quality measuring devices are commonly available.

1 . Portable measuring devices for periodic and one-time measurements: Devices with high precision, expensive, widely used by companies providing measurement and calibration services.

2. They are devices that can be described as home type, have low sensor sensitivity, are mainly intended for measurement, have limited device recording feature, and have models that allow remote access.

It does not seem possible to connect the devices based on measurement to an existing ventilation system and/or a newly installed ventilation system. These devices are mostly suitable for personal use at home.

LIST OF FIGURES

Figure 1. Air quality measurement and control automation electronic cards and carrier platform bottom view.

Figure 2. Air quality measurement and control automation electronic cards and carrier platform top view.

Figure 3. Microprocessor software development board view.

Figure 4. Expansion board back view.

Figure 5. Carrier platform view.

Reference Numerals of Elements

1 . UVC (Ultraviolet C) control isolated output connector

2. High voltage control isolated output connector

3. Ozone generator control isolated output connector

4. TCP/IP-RJ45 internet connector

5. First physical RS485 bus connector 6. Primary 2-way LISB-A connector

7. Second physical RS485 bus connector

8. Physical RS485 bus transceiver integrated circuit

9. Electrostatic discharge, high voltage protector, balancing and termination unit

10. Second 2-way LISB-A connector

11 . Expansion (GPIO) Board

12. Physical RS485 bus auto answer module

13. Main control expansion board physical RS485 bus and control connector

14. Particle sensor physical RS485 bus and control connector

15. Particle sensor transceiver module

16. Static discharge and high voltage protector

17. Particle sensor physical RS485 bus auto answer module

18. Supply input (24 V DC)

19. Linear voltage regulator unit

20. Fan

21 . Motor PID control connector

22. Fan connector

23. Optical isolator

24. Main control expansion board

25. Voltage generator module (0-10 V DC)

26. Oscillator (32,762Mhz)

27. Real Time Clock (RTC) Module

28. Motor control microcontroller

29. Software programming connector (ICSP)

30. Touch, colour screen

31 . Mounting slots

32. Particle sensor air outlet duct

33. Particle sensor air inlet duct

34. Particle sensor

35. Carrier platform

36. Development board mounting slots

37. Distance for expansion board mounting

38. Particle sensor mounting cover mounting slots

39. Development board 40. Expansion board GPIO connector

41 . Real Time Clock (RTC) battery

42. Expansion board mounting slot

43. Particle sensor housing

44. Particle sensor sampling air inlet duct

45. Particle sensor sampling air outlet duct

46. Fan housing

DETAILED DISCLOSURE OF THE INVENTION

An air quality measurement and control system that comprises a control board with a main processor, on which the operating system and/or software can be run to measure an air quality parameters, with at least one sensor that can be connected to this board with different communication physical ways, that has a structure that can evaluate the data coming from the sensor, store them, publish them over the internet, report them, transfer the data to other devices via Wi-Fi/cable, and control them by connecting to devices with different features used to improve air quality, comprising the necessary hardware infrastructure to connect to sensor nodes that are connected to each other and exchange information with each other with a wireless sensor network (Wireless Sensor Network WSN), will also detect the harmful chemicals in the place where it is installed and operate the audible and light warning system, will be able to detect the fires through the sensors in the system and operate the sound and light warning system, can be used in the form of a fixed or portable system and sensors connected to the system, or can be used as a completely mobile system with sensors, can connect many sensors to one another with more than one main system and cellular structure by using a cellular structure through which data communication can be provided, and comprises electronic hardware, electronic sensor hardware, firmware software of main control and sensor units and software of remote connection devices that can be connected to a single centre if desired and able to transfer data to this centre.

In the use of mobile units, the energy requirement of the system is provided by accumulators and/or batteries. Li-ion batteries are preferred due to their rechargeable features.

The system comprises main control module, engine control unit, WSN module, real time clock module, fan (20), linear voltage regulator unit, automatic answering module, digital data transmission module, colour touch screen, sound and light warning system, chemical hazard and fire warning unit, O2 measurement unit, CO2 measurement unit, pressure measurement unit, humidity measurement unit, temperature measurement unit, ozone measurement unit, and laser particle measurement unit.

Said fan (20) cools the electronic components of the system by drawing air in.

Diagram 1 . Air quality automation block diagram RS485 physical data transmission module with auto answer mode:

Communication in digital electronics is done using different physical layers and different protocols. RS232, RS485, I2C, SPI, OneWire physical layers also use different communication protocol structures. Sometimes different protocols can be used on the same physical structure, such as ModBus, CanBus.

Existing sensing sensors use any of these physical protocols. These physical layers have different advantages and disadvantages compared to one another. Mostly TTL serial, I2C, SPI, OneWire physical layer is used in sensor groups. TTL serial is a very cheap and very low complexity physical data bus that can operate at different speeds. While it works in the range of 0-5V in TTL structures, for example, in serial port structures (RS232) in computers, it works in the range of -13/+13V. The ideal distance is 90 cm cable length. One device can be connected to a line. It supports bidirectional communication. There are two buses (RX, TX). I2C is a data bus where 126 devices can be connected by addressing on the same line. It is mostly used for communications on the same board. The data path is short. It is operated in Master- Slave mode according to the addressing technique. The slave device answers the questions of the master device. There is a two-way communication. There are two bus lines (SCL, SDA). Communication is done via the clock signal bus and the data bus. The data path works bidirectionally. SPI communication has five bus lines, including the selection and clock frequency lines, along with two bus lines. The RS485 bus line uses two bus lines for half duplex and four bus lines for full duplex. A maximum of 1200 meters is accepted for the connecting line length. In addition, it has a structure that is least affected by external noise. This connection technique is used in many industrial areas and 126 devices can be connected on the same line.

RS-485 drives are designed to provide 60 mA. This 60 mA is determined by connecting 32 receivers to the circuit, including the termination resistor in the system and considering the worst conditions. RS-485 drivers have a thermal shut-off feature and protect the central processing unit by not allowing excessive current to be drawn from A and B terminals. The input resistance of RS-485 receivers is standardized as 12Kohm. The RS485 standard allows 32 transceiver pairs to be connected to the system at the same time. However, in exceptional cases, 64 or even 128 terminals can be connected to the system at very low speeds. However, stable operation of the system cannot be guaranteed.

RS485 specifications:

Maximum number of drivers: 32

Maximum number of recipients: 32 Mode of operation: Half Duplex

Network Structure: Multipoint connection

Maximum Working Distance: 1200 metres

Maximum speed with 12 m cable length: 35Mbps

Maximum speed with 1200 m cable length: 100kbps

Receiver input resistance: 12k ohm

Receiver input sensitivity: +/- 200mvolts

Receiver input range: -7... 12 volts

Maximum drive output voltage: -7... 12 volts

Minimum drive output voltage (with load connected): +/- 1.5 volts

Physical structure constraints play an important role in system design. Although the microcontroller we are using has only one serial interface, due to the large number of devices and sensors that need to be connected to this line, two physical interface converters as slave and master with automatic response mode, suitable for RS485 physical infrastructure, are designed for a communication that will multiplex by opening the serial path to sharing and provide a secure communication opportunity.

Master and slave slave communication units are connected to each other with four cables including power supply.

Master converter method: The TTL RS232 signal from the microcontroller is first buffered [12], Signals that are not processed sequentially with the note gates are processed by the automatic response module [12], According to the situation obtained here, the input terminals of the receiver/transmitter integrated circuit [8] are converted to the polarity appropriate for the sending or receiving state. The signal converted from TLL physical signal structure to RS485 physical structure is sent to the protection module [9] against electrostatic discharge (ESD) and Electrical Fast Transients (EFT). This part protects the circuit against high voltage that will occur at the ends due to effects such as electrostatic discharge or lightning as a result of hand contact. The balancing (Bias) structure varies depending on the number of devices on the line. In RS485, the voltage difference between A and B terminals is required to be 200mV and above. Values below this are considered undefined. If all devices on the line are in RX mode, the line is idle. In this case, the output of the integrated circuit remains in a non-guaranteed state. For this reason, the balancing (Bias) structure is used so that the lines are not idle. It is necessary to make a termination at the beginning and at the end of the node.

Slave converter method: Although the structure of the Slave Converter is the same as the Master structure, there is no bias and termination in the slave structure. Electronic signals coming in physical RS485 form are first transmitted to the ESD/EFT protector [16], The signals from the protector are transmitted to the transmitter/receiver unit [15], Electronic signals from the [17] module, which acts as an automatic response and buffer, are transferred to the sensor units or the built-in microcontroller module.

Diagram 2: Master control unit Physical converter of TTL communication bus to RS485.

Diagram 3: Converter of RS485 physical bus to Slave TTL communication bus.

Engine control unit: Microcontroller with 16 Bit CPU [28] produces square wave with 10 bit resolution PWM (Pulse With Modulation) unit, 10 Khz speed, 3.3V amplitude and 100% adjustable with 0% Duty ratio. The generated square wave is transferred to the rectifier unit. DC voltage with 0V amplitude at 0% Duty ratio and 1.65V amplitude at 100% Duty ratio is obtained linearly in the rectifier unit. 50% Duty ratio ensures 0.825V to be produced. This voltage is transferred to the buffer unit for the purpose of impedance adjustment. The voltage received from the buffer is taken to the non-inverting amplifier unit [25] with a low-pass shelving filter. In this unit, a voltage with amplitude between 0-1 OV is produced to the output in proportion to the input voltage.

The generated voltage is transferred to the BLDC (Brushless DC) brushless motor control unit [21], The reference voltage applied to the input is applied to the PID controlled motor driver unit. The motor rotates at a speed proportional to this reference voltage. The tachometer information about the rotation speed of the motor and the errors that occur in the motor are transferred to the microcontroller CPU via the optical isolation unit [23], This information is also transferred to the main processor over I2C.

The rotational speed of the engine is measured by the signal from the tachometer tip. If the difference between the given rotation speed and the measured rotation speed is a significant value or equal, it is understood that there is no problem in the system. Significant differences with the rotation speed and/or alarm from the error control end are pulled to level 1 and the main processor is notified that there is an error in the system .

In order to perform all these operations, a motor control unit software (firmware) running on the microcontroller [28] was prepared and written on the controller with a specially designed connector [29],

Diagram 4: Motor control unit External control units After the evaluation of the data obtained from the measurement of air quality, if there are parameters that need to be corrected, isolated control modules are designed within the automation unit for the control of external devices in order to enable the devices related to these.

For example, if the indoor temperature drops, operations such as turning on the heater or increasing its value, opening the external ventilation in case of an increase in the CO2 accumulated inside, providing fresh air inlet, taking the indoor air outside with the increase in humidity or activating the humidifier system when it decreases are carried out through these modules.

Although these external modules are connected to the system with an isolated bus, the control supply voltage of the external control circuit is also provided through this system. In this way, it is ensured that the external noise is kept at a minimum level. In addition, warning threshold values have been determined to prevent malfunctioning due to noise.

The control line from the main microcontroller comes to the logical drive module. Here, optical isolation is provided and the controller data is sent to the module to be controlled via a cable. In the controller module, the control data passing through the isolation unit is transferred to the thyristor (SCR) driver. The thyristor modulates the 220V AC voltage applied to the driver input and transfers it to the output. By means of this modulation, the operating conditions of the device connected to its output are determined. If the control signal is in the form of Logic 0 / 1 , it works as on/off, if the control signal is in the form of Clock Pulse at a certain frequency, it gives a regulated output (for example, if there is a motor at its output, it controls the speed of the outdoor unit).

The control terminals given as A and B can have a single control terminal A only or two control terminals A and B according to the module to be controlled [1 ,2,3],

Diagram 5: External control unit control module block diagram.

Laser particle measuring unit: Particulate matter consists of small particles suspended in the atmosphere. Dust, pollen, sea salt, soil particles, mold, soot, smoke and other fine substances are found in mixtures in the air we breathe every time we breathe. Particulate matter larger than 10 micrometers is usually filtered in our nose and throat, according to the EPA. Particles smaller than 10 micrometers can often pass into the lungs. The smaller the particle size, the further it can travel to the cardiovascular system and cause serious health problems.

Respirable coarse particles (PM 10): Diameter: 2.5 micrometer - 10 micrometer. Emission sources; Dust from fossil fuel combustion, construction and other industrial areas, larger particles and pollen from forest fires and bush burning.

Fine particles (PM 2.5 and PM 1.0): Diameter: 2.5 micrometers and smaller. Emission sources; fossil fuel combustion (gasoline, oil, diesel fuel), particulates in smoke from forest fires, particulates from industries and cars reacting in the atmosphere. The particle measurement unit is designed to calculate the number and size of the particle particles in the samples taken from the air at a speed of 0.5Lt/h [34],

The data coming via the physical RS485 bus first comes to the ESD/EFT protector [16] unit. The electrical signals coming from here enter the receiver/transmitter integrated circuit [15], The buffer [17] connected to this unit stabilizes the incoming data and transmits it to the communication line of the particle sensor. In addition, the connector [13] comes with two control ends with optical isolation. These ends are connected to the corresponding Reset, Set ends.

Diagram 6: Data communication module with automatic response mode and laser particle measurement sensor unit.

Working method :

• A laser diode emits a beam of light through a cavity.

• A fan (20) draws air into the space with fine dust particles suspended in the air.

• As the laser beam shines through the air, dust particles deflect or scatter some of the laser light.

• A light sensor called a photodiode measure how much laser light is transmitted through the gap and how much is scattered by dust particles.

• The microprocessor in the sensor converts light measurements into dust concentration measurements using a process called Mie scattering theory (named after German physicist Gustav Mie).

• The measurement values are transferred to the communication module with automatic response mode in numerical format.

• The transferred data is processed by the main processor and made usable.

Diagram 7: Particle Sensor block diagram and sampling method.

Ozone measuring unit: The electrochemical ozone detection module is used to measure the amount of ozone in the environment. Since the sensor works with 3.3V, there is a linear 3.3V regulator on the measurement module to supply the unit. The +5V supply that comes with the communication line is converted to +3.3V with the voltage level converter and applied to the sensor.

The data coming via the physical RS485 bus first comes to the ESD/EFT protector [16] unit. The electrical signals coming from here enter the receiver/transmitter integrated circuit [15], The buffer [17] connected to this unit stabilizes the incoming data. Since the physical structure in the communication is at the TTL level, that is, in the range of 0-5V, this level must be converted to 0-3.3V with a voltage converter. The converted bus can thus be connected to the standard bus. The measuring range is between 0~10ppm and the measurement accuracy is 0.01 ppm.

Diagram 8: Ozone measuring sensor unit.

Pressure and Differential Pressure Measurement Unit: It is a unit designed to measure pressure and differential pressure. This unit uses the physical RS485 bus to connect to the main processor. After the physical RS485 bus is converted to TTL data structure, it is connected to the TTL communication terminals of the microcontroller inside the unit. This microcontroller is connected to the pressure sensor using the I2C communication bus with the firmware written in it. In order for the sensor to work, the +5V supply voltage at the input is converted to +3.3V with a linear regulator. Since the microcontroller works with +5V and the sensor +3.3V voltage, a voltage level converter has been added to the circuit for I2C communication. In I2C communication, there are SCL, SDA terminals. While the SCL terminal generates the clock pulses during communication, the SDA terminal is used for bidirectional data transport.

There were two different units designed according to the area to be measured. While the first unit can measure -500~0~500 Pa range, the second unit measures -1000 ~0~1000 Pa range.

Diagram 8: Pressure measuring sensor unit. Temperature, humidity and temperature/humidity measuring units: It is designed to work with both analogue and digital sensor types. While NTC type negative thermocouple sensor is used for analogue temperature measurements, sensors working with Onewire protocol are used for digital temperature measurement. In addition, as a third type, a sensor that can measure both humidity and temperature at the same time and works with I2C communication protocol is used.

The sensors used in analogue measurements are elements whose resistance changes according to the temperature value. They respond by decreasing the resistance value when the temperature rises, and by increasing the resistance value when the temperatures decrease. The details of the measurement technique made with the ADC are also explained in the software part.

Diagram 9: Analogue temperature measurement sensor unit.

Diagram 10: Digital temperature, Temperature/Humidity measurement sensor units.

Chemical Warning and Fire Alarm Units: It is a system consisting of chemical sensors suitable for the place where the system will be installed. Carbon monoxide sensors are used for fire alarm. Since most of the gas sensors are analogue, measurements are made via ADC. Measurement values and warning signals are sent via the physical communication bus. Sensors such as carbon monoxide (CO), nitrogen dioxide (NO2), nitrogen monoxide (NO), hydrogen sulfide (H2S), chlorine (Cl_ ₂ ), and ammonia (NH3) can be used with this module. Different sensors suitable for needs can be integrated into the system.

Diagram 11 : Chemical warning and Fire Alarm sensor units:

Main Control Unit: A microprocessor development board is used as the main control module. There are UART module, SD card module, USB and Network module, RAM, and TFT display modules on the development board. There are also GPIO (General Purpose Input Output) terminals.

Android IOT software is installed on the development board as the operating system with a suitable method. A java-based Android control software has been prepared for the control software. In addition, the main software is used to connect external devices via WiFi, TCP/IP.

Connection to measurement and control modules is made via RS485 digital data transmission module with automatic answering mode via uart. In this way, the single serial communication on the development board is multiplexed and the communication distance is increased, thus ensuring its connection with other modules.

Diagram 12: Block diagram of microprocessor development board. Sensor data reading techniques: Reading errors of a sensor can be caused by the sensor itself, the circuit design, its connection with the circuit, the location of the sensor, corrosion and rusting effects that occur over time, as well as environmental effects. Examples of these are WiFi/RF sources, magnetic fields, thermal radiation, ionizing radiation, fluorescent lamps, motors. Errors are examined in two parts: random errors and systematic errors.

Random errors can be evaluated by statistical methods. These errors are mostly caused by the sensor, as well as the supply and current sources can cause these errors.

Systematic errors are caused by external influences, design and installation. Sensors in a magnetic field are more prone to this type of error. The heating of the sensor itself also creates an error. RF source noise can cause both random and systematic errors.

Since it is very important to prevent these errors and to get the correct values in measurement systems, processes that improve stability and sensitivity for the ADC unit have been developed and implemented through the software.

ADC (Analogue to Digital) circuits or integrated circuits produced for this are used to convert an analogue information into digital. Although ADCs have different techniques and speeds, there are two main points in the conversion business. It is the reference voltage and the number of bits that determines the converter resolution.

Basically, the following method is used when measuring with an ADC. How many mV can be read in one step is determined by dividing the reference voltage by the number of bits:

Reference Voltage: 5V

Resolution : 10 Bits

Step Voltage = 5000mV / 1024 = 4.8828125 mV

Or

Reference Voltage: 2.5V

Resolution : 16 Bits

Step Voltage = 2500mV / 65535 = 0.03814755 mV That is, the voltage that the ADC can measure is 4.8828125 mV and its multiples for 10 Bits, 0.03814755 mV and its multiples for 16 Bits. For example, if we assume that the voltage we want to measure is 1 ,2V.

Number of steps = 1200 mv 14.8828125 => 245.76

Since the ADC works as an integer, it will give us the value 245. When this is entered into the calculation, the Measured voltage = 245 * 4.8828125 = 1.196,2890625 mV. That is, the ADC will measure with an error of about 3.7 mV. To reduce this error, it is necessary to increase the resolution.

High resolution ADC significantly increases production costs. For this reason, for the 10-bit resolution ADC built into the microcontroller, a method has been applied to increase the software resolution, to minimize the reading errors and to eliminate the problems caused by the external environment noises. The resolution of the current ADC unit is 10 Bit.

1. Depending on the number of bits (n) that is planned to be increased in software, 2 ²⁽ⁿ ’ ¹⁰⁾ sample values are read from the ADC.

2. The readings are collected in an accumulator.

3. The total value obtained is divided by 2 ⁿ ’ ¹⁰ .

4. The number of steps of the ADC is calculated. DivisionRate= 2 ⁿ -1

5. StepV = Vref I DivisionRate step voltage is calculated by dividing the reference voltage of the ADC by the number of steps.

6. ADC voltage is calculated according to the amplified bit value.

Moving average algorithm is applied on the obtained ADC value. The moving average algorithm is mostly used in money markets. In addition to calculating where the prices will reach in the moving average money markets, it also gives information about the changes in the current direction with a delay. In short, the moving average gives the average of a data set over the selected period. In this way, fluctuations are kept to a minimum as the instantaneous peak values in the data set are smoothed within the mean. Triangular filter, one of the moving average types, was applied to the obtained ADC data set. Triangular mean FIFO logic is used. The values measured in the triangular mean are multiplied by the coefficients that will form a triangular form according to the filter size and divided by the sum of these coefficients. Thus, the average value is obtained according to the centre point within the target range. This provides softening of the sudden peak values in the readings. Thus, the effect of external and internal errors in reading on the output is kept to a minimum.

1 . The array size is specified as an odd number (F). F=15

2. The midpoint is calculated (M). M= (F+1 )/2

3. The partition coefficient is calculated (R). R= Mx(M+1)

4. The moving average is calculated.

The formula [4] is used to calculate the temperature depending on the R value obtained. Here, T25 is the equivalent of 250 Celsius in Kelvin, and R25 is the equivalent of resistance at this temperature.

T25 = 298,15 K

The water vapour in the air is called humidity. Humidity is present in every habitable air mass. Absolute humidity is the amount of humidity in 1 m ³ of air in grams. Maximum humidity is the maximum amount of humidity that 1 m ³ of air can hold. In other words, the air is saturated with humidity. It is directly proportional to temperature. Humidity, which is determined as relative humidity, relative humidity, or proportional humidity, is the ratio of absolute humidity to maximum humidity. The temperature value plays an important role in humidity calculations. Because air temperature is directly related to the amount of humidity the air can carry. RH : Relative humidity

P : Absolute humidity

Pmax : Maximum humidity

P RH[%RH] = - - x 100

‘ max

VH : Volumetric humidity

Va [m ³ ] : Volume

Mw [g] : Steam weight

SH : Specific humidity

Mw [kg] : Volume

MDA [kg(DA)] : Steam weight

Supply unit: A 3.0 A, Step Down switched regulator circuit is designed for the supply of the system. By adding a notch filter on the circuit, it is ensured that the circuit is filtered against noise. Notch filters: are special type of band-stop filters and are produced by designing the bandwidth of the BDF to be very narrow. In biomedical engineering applications, it is generally used to suppress 50 Hz noises caused by mains voltage. Notch filters are filters that absorb a single frequency value or a very narrow frequency band according to their design. There are also LPF (Low Pass Filter) and HPF (High Pass Filter) filters in the structure of notch filters. However, in these filters, each sub-filter layer consists of two sub-filters positioned symmetrically to each other. Because of this symmetrical structure and the appearance of the circuit connection, it is called as Twin-T (Twin-T) and because the frequency response graph of the filter resembles a notch, it is called a Notch filter. The cutoff frequency of the notch filter fC is the geometric mean of the lower and upper cutoff frequencies of LPF and HPF filters, which are very close to each other.

Cutoff frequency of LPF layer: Cutoff frequency of LPF layer:

The geometric mean of fL and fH values, fC, is calculated as follows.

Diagram 13: Supply unit with notch filter.

PID control: The controller control loop method, which consists of the first letters of the words proportional-integral-derivative PID, is a feedback controller method widely used in industrial control systems. A PID controller continuously calculates an error value, i.e., the difference between the intended system state and the current system state, by comparing a desired value to the current state. The controller tries to minimize the error by adjusting the process control input. There are three values in PID calculations; proportional, denoted by P; the integral is denoted by I; derivative, denoted by D. Considering the obtained values and the current change, it is interpreted as follows; P is the current error, I is the sum of past errors, and D is an estimate of future errors. This algorithm has been converted into a software algorithm for the microcontroller. Formula 11 or formula 12 can be used for the calculation process. The K _c parameter in the dependent form effectively uses the Kp, Ki and Kd values as a scalar multiplier.

Dependent form:

Independent form:

C de(t u(t) = K _p e(t) + Kt e(t)dt + K _d ——

J dt o

r(t) reference e(t) is the difference between the u(t) proses input y(t) process set point process output desired set point control value output

Diagram 14: PID calculation block diagram

Diagram 15: Firmware PID encoding

Real time clock: A ready-made RTC integrated circuit [27] is used for real time clock implementation. It is operated with a crystal [26] at 32,768 Khz. A battery support [41] has been added for the RTC IC so that the clock can continue to run in case of power cut or disconnection. The I2C communication bus is connected to the main and the main processor. In addition, a timing warning is provided by connecting the 1 second trigger tip to the trigger input terminal of the main processor to create an interrupt.

Motor control unit software (Firmware): The motor control unit is designed with a 32Mhz microcontroller [28], The microcontroller is connected to the main processor as a slave over the I2C line. In the microcontroller, PWM and Alarm terminals are defined as output, tachometer and fault terminals are defined as isolated inputs. The 10-bit resolution PWM unit is programmed to give the required electrical signal for the 0-1 OV voltage generator [25] at an adjustable Duty rate between 0% and 100% at 10Khz. It produces output voltage by adjusting the PWM duty ratio in line with the orders from the main processor. This output voltage is applied to the brushless DC motor driver and the motor rotation is provided at the desired speed ratio. The accuracy of the adjustment is ensured by measuring the signal [21 , 23] coming from the tachometer input end. If an error is detected in the rotation of the motor or an error signal from the motor is transmitted to the main processor digitally (logic 0/1 ) via the error terminal [21 ,23], llart, timer interrupts are used in the software. A very short and fast coding has been developed so that delay and error detection can be full-time.

Software (Firmware) for sensor data readings: Different reading techniques have been applied according to the type and model of the sensor used in the sensor units, which are designed to operate independently as an integrated unit.

Analogue temperature measurement: NTC type sensors are used. These sensors are temperature sensitive resistors. As the temperature rises, the resistance decreases, and when the temperature decreases, the resistance increases. Therefore, these readings use the ADC. The resistance value is calculated by using the overload method and triangular average methods using the 10-bit resolution ADC unit equations [2] and [3] of the on-board microcontroller. The temperature data is obtained by substituting the obtained values in the equation [4],

Digital temperature measurement: The sensor used is connected to the built-in microcontroller with the onewire connection method. Temperature data read by the built-in microcontroller is sent to the main processor by converting the serial interface data line to a physical RS485 line. In the reading process, the built-in microcontroller performs the reading process by writing the commands related to the sensor to the sensor data bus.

Digital temperature/humidity measurement: The sensor used is connected to the built-in microcontroller with the I2C connection method. Temperature/humidity data read by the built-in microcontroller is sent to the main processor by converting the serial interface data line to a physical RS485 line. In the reading process, the built-in microcontroller performs the reading process by writing the commands related to the sensor to the sensor data bus.

Analogue humidity measurement: Resistive type humidity sensors are used. These sensors can be thought of as humidity sensitive resistors. While the resistance decreases with the increase in humidity, the resistance increases when the humidity decreases. Therefore, these readings use the ADC. However, AC voltage should be used for the analogue humidity sensor. Therefore, the voltage obtained with a built-in DC-AC is applied on the sensor. The AC signal from the sensor is first converted to DC voltage to be read by ADC. The resistance value is calculated by using the overload method and triangular average methods using the 10-bit resolution ADC unit equations [2] and [3] of the on-board microcontroller. The temperature value is needed to evaluate the obtained data. The temperature values that are read from the temperature sensor and sent to the main processor are sent to the humidity measurement unit with the read command during the reading process. The resistance value read is sent to the main processor by measuring the humidity as a percentage using the relevant resistance value depending on the temperature value from the table built into the microcontroller.

Pressure, differential pressure measurement: The sensors used in pressure and differential pressure measurement use the I2C communication bus. The data coming from the sensors connected to the built-in microcontroller via this bus, and the temperature data read with the built-in microcontroller, are sent to the main processor by converting the serial interface data line to a physical RS485 line. In the reading process, the built-in microcontroller performs the reading process by writing the commands related to the sensor to the sensor data bus. Ozone measurement: The serial terminal of the sensor used is connected to the main processor with a physical RS485 converter. Since the sensor works with +3.3V, there is a level converter between the sensor and the built-in microcontroller. Through this converter, the built-in microcontroller performs the reading process by writing the commands related to the sensor to the sensor data bus.

CO2 measurement: The serial terminal of the sensor used is connected to the main processor with a physical RS485 converter. Since the sensor works with +3.3V, there is a level converter between the sensor and the built-in microcontroller. Through this converter, the built-in microcontroller performs the reading process by writing the commands related to the sensor to the sensor data bus.

O2 measurement: The serial terminal of the sensor used is connected to the main processor with a physical RS485 converter. Since the sensor works with +3.3V, there is a level converter between the sensor and the built-in microcontroller. Through this converter, the built-in microcontroller performs the reading process by writing the commands related to the sensor to the sensor data bus.

Active Radon gas measurement: The serial terminal of the sensor used is connected to the main processor with a physical RS485 converter. Since the sensor works with the method of measuring alpha particles emitted from Radon gas, it needs high voltage. For this reason, it has its own special supply and high voltage generator stage. It works on the basis that alpha particles passing through an ion chamber change conductivity. The generated values are evaluated with the built-in microcontroller and sent to the system over the communication line.

Chemical warning and fire alarm: If hazardous chemicals are used at the place where the system will be installed, control boards consisting of appropriate sensors for the relevant chemicals will be used in order to predict the dangers that may arise for human health in case these chemicals are mixed into the air. The legal ones of these chemicals that may be in the air are defined in the software and if these values are exceeded, the main control sends the necessary warnings to the processor. Main control software: The necessary infrastructure for serial TTL, I2C, OneWire communication has been prepared in the software.

• The necessary infrastructure for USB devices that can be connected externally has been prepared in the software.

• The infrastructure required for WiFi and TCP/IP connection and the infrastructure required for UDP communication have been prepared in the software. The necessary infrastructure for the use of the system as a Web server is available in the system.

• The characteristics of the terminals were determined by making definitions for the GPIO terminals in the software.

• Pins are defined for PWM. Its features are introduced to the system. Necessary procedures for its use are defined.

• Relevant procedures are defined for the RTC module.

• Necessary procedures for motor control and fault detection are defined.

• Procedures are defined for measurements of particles, ozone, pressure, O2, CO2, temperature, humidity, and other gases.

• A communication protocol is defined for the automatic response mode communication unit and this protocol is used for the communication of the units and the main controller.

• Since the information, data format and data lengths from each sensor are different, separate data analysis procedures are designed for each sensor (for example, particle data is 32 bytes long, ozone data is 8 bytes long, and each byte/bit has different meanings in each sensor).

• A GUI (Graphics User Interface) is designed for the user. This interface is used both for visualizing incoming data and for setting up the device. In addition, visual warnings and alarms are also delivered to the user via this GUI.

• Necessary procedures for network, UDP, LAN and WNS have been defined, infrastructure required for internet bus connection and cellular data connection has been prepared.

• Features such as reporting and graphical display on the GUI have been added and these data can be viewed via remote access. • The automatic opening and closing times of the device have been made programmable by adding a timer to the software.

• With the timer added to the software, it is possible to perform the cleaning of the environment with Ozone with remote access or with a timing control, without the users inside, and the health of the user is protected in this way. In addition, audible and visual warnings are provided until the ozone gas level inside decreases to appropriate values.

• Necessary infrastructural procedures have been defined for logging into the system, data monitoring and control of mobile phones with remote access from the IP address defined in the system.

• Automation procedures have been prepared in order to control functions such as on/off or adjust the speed of external control devices for automation purposes. These procedures are used to control devices with different purposes and features (e.g. heaters, humidifiers, ventilation flaps).

Remote access software for mobile phone: It has a software with the necessary infrastructure for accessing the main system, viewing system values and changing system settings with a software to be installed on mobile phones for remote access.

Calculation of Air Quality Index (AQI):

A standard value between 0-500 is obtained by placing the average values obtained from the air quality index PM2.5, PM10, SO2, NOx, NH3, CO and 03 measurements into a formula. This value gives information about the state of air quality.

• For PM2.5, PM10, SO2, NOx and NH3, the average value over the last 24 hours is used, provided that the value obtained is at least 16 items.

• For CO and OD, the maximum value from the last 8 hours is used. • Each measure is converted into a Sub-Directory based on predefined groups.

• Sometimes measurements are not available due to lack of measurement or lack of required data points. In this case, this measurement average is not taken into account.

• The result is the maximum Sub-Index provided that at least one of AQI, PM2.5 and PM 10 is present and at least three of the seven measurements are present.

PM2.5 Calculation: PM2.5 is measured in ug/m3 (micrograms per cubic meter of air).

1 . If average<=30, the Calculation = (average*50) /30

2. If average<=60, the Calculation = 50 + (average- 30) * 50 / 30

3. If average<=90, the Calculation = 100 + (average- 60) * 100 / 30

4. If average<=120, the Calculation = 200 + (average- 90) * 100 / 30

5. If average<=250, the Calculation = 300 + (average- 120) * 100 / 130

6. If average<=250, the Calculation = 400 + (average- 250) * 100 / 130

7. If the average does not meet the above conditions, Calculations

PM10 Calculation: PM10 is measured in ug/m3 (micrograms per cubic meter of air).

1 . If average<=50, the Calculation = average

2. If average<=100, the Calculation = average

3. If average<=250, the Calculation = 100 + (average- 100) * 100 / 150

4. If average<=350, the Calculation = 200 + (average- 250)

5. If average<=430, the Calculation = 300 + (average- 350) * 100 / 80

6. If average<=430, the Calculation = 400 + (average- 430) * 100 / 80

7. If the average does not meet the above conditions, Calculations

Sulphur Dioxide (SO2) Calculation: SO2 is measured in ug/m3 (micrograms per cubic meter of air).

1 . If average<=40, the Calculation = average * 50 / 40

2. If average<=80, the Calculation = 50 + (average- 40) * 50 / 40

3. If average<=380, the Calculation = 100 + (average- 80) * 100 / 300

4. If average<=800, the Calculation = 200 + (average- 380) * 100 / 420

5. If average<=1600, the Calculation = 300 + (average- 800) * 100 / 800 6. If average<=1600, the Calculation = 400 + (average- 1600) * 100 / 800

7. If the average does not meet the above conditions, Calculations

Nitric x-oxide (NOx) Calculation: NOx is measured in ppb (parts per billion).

1 . If average<=40, the Calculation = average * 50 / 40

2. If average<=80, the Calculation = 50 + (average- 40) * 50 / 40

3. If average<=180, the Calculation = 100 + (average- 80) * 100 / 100

4. If average<=280, the Calculation = 200 + (average- 180) * 100 / 100

5. If average<=400, the Calculation = 300 + (average- 280) * 100 / 120

6. If average>400, the Calculation = 400 + (average- 400) * 100 / 120

7. If the average does not meet the above conditions, Calculations

Ammonia (NH3) Calculation: NH3 is measured in ug/m3 (micrograms per cubic meter of air).

1 . If average<=200, the Calculation = average * 50 / 200

2. If average<=400, the Calculation = 50 + (average- 200) * 50 / 200

3. If average<=800, the Calculation = 100 + (average- 400) * 100 / 400

4. If average<=1200, the Calculation = 200 + (average- 800) * 100 / 400

5. If average<=1800, the Calculation = 300 + (average- 1200) * 100 / 600

6. If average<=1800, the Calculation = 400 + (average- 1800) * 100 / 600

7. If the average does not meet the above conditions, Calculations

Carbon Monoxide (CO) Calculation: CO is measured in mg/m3 (miligrams per cubic meter of air).

1 . If average<=1 , the Calculation = average * 50 / 1

2. If average<=2, the Calculation = 50 + (average- 1 ) * 50 / 1

3. If average<=10, the Calculation = 100 + (average- 2) * 100 / 8

4. If average<=17, the Calculation = 200 + (average- 10) * 100 / 7

5. If average<=34, the Calculation = 300 + (average- 17) * 100 / 17

6. If average<=34, the Calculation = 400 + (average- 34) * 100 / 17

7. If the average does not meet the above conditions, Calculations

Ozone (03) Calculation: 03 is measured in ug/m3 (micrograms per cubic meter of air). 1 . If average<=50, the Calculation = average * 50 / 50

2. If average<=100, the Calculation = 50 + (average- 50) * 50 / 50

3. If average<=168, the Calculation = 100 + (average- 100) * 100 / 68

4. If average<=208, the Calculation = 200 + (average- 168) * 100 / 40

5. If average<=748, the Calculation = 300 + (average- 208) * 100 / 539

6. If average>748, the Calculation = 400 + (average- 400) * 100 / 539

7. If the average does not meet the above conditions, Calculations

Calculation of Indoor Air Quality Index (IAQI):

The values used in the AQI calculation are calculated by taking the average of the data taken within 8 hours and 24 hours. Although these average values are suitable for measuring outdoor air quality, they are not suitable for measuring indoor air quality. Because exposure to inappropriate values in closed environments is likely to cause serious health problems, even for a short time. For this reason, the IAQI value, which is calculated by using the average of the samples taken every ten seconds in a minute instead of the long-term average, is important in terms of providing more accurate results as well as enabling the actions to be taken to increase the indoor air quality immediately.

Air quality measurement and control system that uses WSN (wireless sensor network) enabled sensors to measure, evaluate, store, and report of air quality in the area and to provide remote data communication comprises

• at least one main control module that can run operating system and/or software on it, and evaluates, stores, reports, publishes the data it receives over Internet, and exchanges data and/or commands by connecting to external devices,

• at least one sensor that can be connected to said main control module by means of communication physical means and that enables the measurement of air values,

• at least one motor control unit that provides feedback control of the operating parameters of at least one motor to be operated for the regulation of air parameters by means of the motor control unit software running on it, with PID (Proportional, Integral, Derivative) algorithm, • at least one WSN module that enables said at least one sensor to be connected to said main control board and/or to each other,

• at least one linear supply regulator unit (19) that enables the incoming energy to be converted into voltage and/or current values suitable for the system elements in order to meet the energy need required for the operation of the system,

• at least one physical RS485 bus transceiver integrated circuit (8) and data transmission module that enables data exchange between the elements in the system,

• at least one physical RS485 bus automatic answer module (12) that converts the data into the appropriate data type for said physical RS485 bus transceiver integrated circuit (8) and/or the system element to which it will be sent,

• at least one coloured touch screen (30) on said main control module that enables the user to enter data into the system and/or monitor the system data by working through the GUI (user graphic interface), and

• at least one main control software that runs on said main control module and controls the operation of the system according to the air index parameter it calculates from the data it receives.

In a preferred embodiment of the invention, there is at least one warning module that provides an audible and/or visual and/or written and/or lighting warning if the air quality is outside the predefined ranges.

In a preferred embodiment of the invention, there is at least one warning module that provides audible and/or visual and/or written and/or lighting warnings against chemical and/or fires, by means of the data received from at least one sensor.

A preferred embodiment of the invention comprises

• at least one real time clock module that enables the system to work in accordance with real time,

• at least one crystal oscillator (26) enabling said real time clock module to generate clock signals, and • at least one real time clock (RTC) and battery (41) that enables real time synchronization to continue in case of power failure.

A preferred embodiment of the invention may also comprise at least one fan (20) that provides cooling of the electronic components of the system by drawing air inside.

In a preferred embodiment of the invention, at least one digital data transmission module is seen that enables the received and/or translated data to be transmitted digitally to the elements in the system.

In a preferred embodiment of the invention, said at least one sensor is at least one of oxygen, carbon monoxide, carbon dioxide, nitrogen monoxide, humidity, nitrogen dioxide, hydrogen sulphide, ammonia, pressure, differential pressure, humidity, temperature, ozone, active radon gas and/or laser particle sensors (34).

A preferred embodiment of the invention may also comprise

• at least one O2 measurement unit, in communication with said main control module, which converts the oxygen data of the air taken from at least one sensor into a suitable data format and sends it to the main control module,

• at least one CO2 measuring unit, in communication with said main control module, which converts the carbon dioxide data of the air taken from at least one sensor into a suitable data format and sends it to the main control module,

• at least one pressure and differential pressure measuring unit, in communication with said main control module, which converts the pressure and differential pressure data of the air taken from at least one sensor into appropriate data format and sends it to the main control module,

• at least one at least one humidity measuring unit which, in communication with said main control module, converts the humidity data of the air received from at least one sensor into a suitable data format and sends it to the main control module, • at least one temperature measuring unit, in communication with said main control module, which converts the temperature data of the air received from at least one sensor into a suitable data format and sends it to the main control module,

• at least one ozone measuring unit, in communication with said main control module, which converts the ozone data of the air taken from at least one sensor into a suitable data format and sends it to the main control module,

• at least one laser particle measurement unit that, in communication with said main control module, converts the airborne particle data received from at least one sensor into a suitable data format and sends it to the main control module,

• at least one control board, in communication with said main control module, which converts chemical and/or fire data received from at least one sensor into appropriate data format and sends it to the main control module, and

• measuring units software that monitors the operation of said measuring units.

In a preferred embodiment of the invention, said physical RS485 bus transceiver integrated circuit (8) may comprise

• RS485 physical data transmission module with at least one autoanswer mode enabling operation,

• at least one converter interface that provides data type conversion during data transmission, and

• electrostatic discharge, high voltage protector, balancing and termination unit (9), which provides protection of the circuit from high current and/or voltage.

In a preferred embodiment of the invention, said motor control unit comprises

• at least one motor control microcontroller (28) with a CPU (central processing unit) acting as a processor, • at least one PWM (Pulse Width Modulation) unit that enables the generation of control signals,

• at least one rectifier unit that converts the signals produced in the said PWM unit to DC (direct current) voltage,

• at least one buffer that enables impedance matching to be performed for efficient use of the signal,

• at least one low-pass shelving filter providing elimination of unwanted frequencies at the output of said buffer,

• at least one non-inverting voltage generator module (25) which provides a non-inverting amplification of the signal at said shelving filter output,

• at least one PID controlled motor driver unit that enables the motor to rotate according to the speed coming from said voltage generator module (25),

• at least one tachometer, which provides information about the rotation speed of the motor and the errors that occur in the motor as feedback, and

• at least one optical isolator (23) that protects the microcontroller (28) against the over-voltage and/or current values of the signals of the feedback information received from said tachometer..

In a preferred embodiment of the invention, said main control unit comprises

• at least one development board (39) acting as a processor,

• at least one LIART (Universal Asynchronous Receiver-Transceiver) module that provides asynchronous communication with other system elements by working on said development board,

• at least one RAM (Random Access Memory) with internal storage,

• at least one SD (Secure Digital) card module with external storage,

• at least one USB (Universal Serial Bus) and network module providing storage space entry and communication,

• terminals for connecting external input-output units,

• at least one operating system that enables the system to run by being installed on any of said storage units, • at least one ethernet port that enables the system to connect to the Internet,

• at least one camera input that enables image acquisition, and

• at least one antenna that enables the module to communicate with the outside.

In a preferred embodiment of the invention, said linear voltage regulator unit (19) has at least one band-stop notch filter providing filtering against electronic noise at the input.

In a preferred embodiment of the invention, there is a remote access software that enables the system to be accessed remotely with a smart device, to view the parameters and to make the setting entries.

In a preferred embodiment of the invention, the external control unit to be operated to bring the air parameters to the desired values comprises

• air conditioner unit controller, which enables the control of at least one air conditioner unit to be used for heating and/or cooling the air,

• ventilation unit controller, which operates in the event of an increase in the accumulated gases inside, and provides control of the ventilation unit that ensures fresh air inlet and/or exhausts the air inside,

• humidifier unit controller, which provides control of the humidifier unit, which works with the increase in the amount of humidity inside and ensures that the air inside is evacuated, or provides the formation of humidity inside by working with the decrease in the amount of humidity inside,

• at least one external control unit that monitors the operation of said air conditioning unit, ventilation unit and humidifier unit and enables them to be connected to said main control module,

• at least one logical drive unit providing the regulation of signals between said main control module and the external control unit, • at least one optical isolation unit that protects said main control module and external control unit from over-voltage and/or current values that may come from each other, and

• at least one thyristor driver unit in said external control unit, which modulates the voltage applied to the input and regulates it according to the operating conditions of the device connected to the output.

A preferred embodiment of the invention also comprises

• at least one supply and voltage generator that provides the high voltage required for measuring alpha particles emitted from active radon gas,

• at least one ion chamber, which allows to change the conductivity of alpha particles emitted from active radon gas,

• at least one active radon gas sensor that enables the measurement of the active radon gas amount in the environment, and

• at least one radon measurement unit that, in communication with said main control module, converts the radon gas data of the air taken from the radon gas sensor into a suitable data format and sends it to the main control module.

In a preferred embodiment of the invention, there is at least one expansion (GPIO) board (11 ) and at least one main control expansion board (24), which increases the number of input and output ends of the system, increasing the number of parameters that can be processed and the number of outputs that can be controlled.

In a preferred embodiment of the invention, there is at least one carrier platform (35) that enables the elements of the system to stay together as a single piece and to be protected against external impacts.

A preferred embodiment of the invention comprises

• at least one particle sensor transceiver module (15), which enables the particle sensor (34) to exchange data with other elements of the system , • at least one static discharge and high voltage protector (16) that protects the module (15) from over-voltage and/or current by being at the input of said particle sensor transceiver module (15),

• at least one buffer, which is located at the output of said particle sensor transceiver module (15), protecting the module (15) from over-voltage and/or current, and/or enabling the incoming information to be transferred with the arrival of the clock signal,

• at least one particle sensor physical RS485 bus automatic response module (17), which enables the particle sensor (34) to convert the data to be suitable for the system element to be sent for data exchange and/or convert the data to be received by the particle sensor (34) into a suitable one for itself,

• at least one particle sensor air inlet channel (33) and at least one particle sensor sampling air inlet channel (44), which allow the air to be measured by the particle sensor (34) to enter the system, and

• at least one particle sensor air outlet duct (32) and at least one particle sensor sampling air outlet duct (45), which allow the air measured by the particle sensor (34) to exit the system.

In a preferred embodiment of the invention, there also is an external battery that provides the energy need to be met when the system is used mobile.