SMART BUILDINGS AND AUTOMATION CE6011 // 2018 //
Thermal mapping using Infrared sensors Group 4
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Equal participation by all groupmates
INDIAN INSTITUTE OF TECHNOLOGY MADRAS
BUILDING TECHNOLOGY AND CONSTRUCTION MANAGEMENT
M. Divya Praneetha Lakshmi Prabha E. P. Mohan Chandra Rishivanth T. Sachin P. R. P. Sindhuja
CE15B037 CE17S005 CE17D017 CE14B041 CE17M015 CE15B042
ACKNOWLEDGEMENT
First and foremost we thank Lord Almighty for helping us complete this project successfully. We would like to thank Prof. Benny Raphael and the Teaching Assistants for guiding us throughout the project. The non teaching staffs have been greatly helpful in the various stages of the project. We would like to express our gratitude to all our classmates and other groupmates who supported us for completing this project successfully. We thank Kislay Anand for helping us with the coding and execution of the project with his expertise in the topic. We would like to thank Department of Civil Engineering for providing us with the facilities to conduct a hands on project on smart building based technology.
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TABLE OF CONTENTS 1. Introduction
1
Aim:
1
Objective:
1
Scope:
1
Limitations:
1
Application:
2
2. Justification
2
Relevance:
2
2
Temperature measurements:
3. Literature Review
3
Master/Slave architecture:
4
UART Communication:
4
Arduino Mega (ATmega2560):
6
Arduino Pro Mini 3.3V:
6
Servo motor (MG995):
7
IR Sensor (MLX90614)
7
Jumper wires
7
Power Adaptor
7
4. Methodolgy
8
5. Design of Experiment
9
Design Considerations
9
Hardware design
9
Circuit and connectivity
11
Coding
12
6. Discussion and Observation
16
Execution
16
Serial output
16
Isotherm plots
16
7. Costing
17
8. Conclusion
17
9. Future Scope
17
10. References
19
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LIST OF IMAGES Image 1: Bimetal thermal sensor
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Image 2: Thermo couple
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Image 3: Thermal image of hot air balloon
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Image 4: UART communication
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Image 5: Arduino AT Mega2560
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Image 6: Arduino ProMini
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Image 7: Servo motor MG995
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Image 8: IR sensor MLX90614
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Image 9: Jumper wire
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Image 10: Power supply adapter
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Image 11: Methodology Chart
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Image 12: Prototype photograph
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Image 13: Prototype photograph
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Image 14: Prototype 3D model
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Image 15: Prototype 3D model structure
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Image 16: Circuit Diagram
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Image 18: Serial data plot
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Image 17: Logic diagram for data flow
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Image 19: Dynamo parametic model
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1. Introduction Thermal comfort has become a major concern in the modern building services design area. The energy consumption for achieving comfort conditions in the buildings constitute the highest amount of energy in the whole life cycle of the modern buildings. The research in the building science areas shows that a better solution to achieve comfort is the use of passive techniques. Smart building solutions incorporate these passive design ideas to the modern buildings in an intelligent manner. While studying the thermal conditions of a room air temperature and the radiant temperature has equal contributions. The temperature due to the heat radiation from the windows, walls, people, appliances, equipments, etc. are considered as the radiant temperature. This project is done to understand how the infrared sensors can be used to measure and determine the amount of radiant heat from different directions, by mounting them at varying heights on a servo motor, to generate the thermal map of a room.
Aim: • To obtain the radiant temperature at different directions of a room using an Arduino to control a rotating a vertical array of infrared sensors mounted on a Servo motor. • To plot the thermal map of the room with the sensor data for 3 heights.
Objective: • To make a working prototype of a setup using controllers, sensors and actuators • To obtain a map of heat sources/ obstructions present in a room
Scope: • The term project is limited to the prototype modelling of the actual system, which is a working model. • The setup is done for a miniature model with MLX 90614 IR sensors and MG 995 Towe Pro Servo motor.
Limitations: • Servo motor rotation: Motor is set on and off to take readings at regular intervals. Exact amount of rotation can’t be controlled as it continues to rotate due to inertia Photo by Stephen Crowley on Unsplash
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• High response time and low detection capability of infrared sensors • Length of jumper wires. • Due to the time and resource limitation, the execution of the telescopic design as a working model was not done.
Application: • By obtaining a thermal map of entire room, we can analyse which areas of the building are most used. So, plotting this with respect to time, could give the peak time usage of a specific location. • The thermal map can identify the different locations in the room which are more heated compared to other points. This data can be used real time to control the air conditioners • We can locate the heat sources in the room like windows and also location of Air conditioning units and adjust their distribution inside the area for localised control. • These IR sensor data can be used for fire safety systems, where the sudden change in the temperature or peak values can be used to sense the presence of fire at early stages.
2. Justification Relevance: The built environment has been subjected to modifications since time immemorial. Human interventions throughout the ages have caused problems like global warming, ozone depletion, rise in sea level etc. The GHG emissions, especially carbon dioxide from the built environment and energy production sector contribute to these environment problem to a great extent. In the modern buildings, the conditioning of space consume a lot of energy and can be saved if we opt to the passive techniques for the building design and service planning. Smart buildings with the technology to understand the immediate surroundings and the
Temperature measurements: Thermocouple: It is a device with two (or more) wires of different metals which are connected at one joint. These sensors measure temperature changes with respect to changes in output voltage between the wired legs. But the obtained output voltage changes are not linear with temperature and hence have to be scaled accordingly. Also, the TC wire that is used to connect sensor and recording device makes the device more expensive. Resistance Temperature Detector(RTD): It works based on the principle that resistance of metals changes with temperature. Electricity is passed through the setup and the changes in temperature are obtained by another controller or monitor connected to the RTD. But, as this is based on the property of resistance changes, any other connecting elements which might add up to resistance changes of the circuit lead to measurement errors. Thermometers: Work on expansion of liquids due to increase in temperature. This kind of device doesn’t give a temperature value automatically. So, we need to record each and every reading manually. GROUP 4
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Silicon Diode: It is specifically designed to measure temperature in cryogenic ranges which is not applicable for our project. Bimetallic Devices : It is a device with two different metals joined together lengthwise and connected mechanically to a pointer. Taking advantage of their expansions at different rates temperature changes can be detected in terms of mechanical displacements. IR Sensors:An IR sensor is a noncontacting temperature sensor which measures infrared radiation emitted in surroundings. It works on the principle of black body radiation. It basically consists of a lens which aids to focus the infrared radiation emitted from surrounds into a thermopile which functions as a detector. The thermopile absorbs the energy from the focused infrared radiation and converts it into heat energy. The heat gained is converted into electrical signals. The resistances and output voltages change proportionally based on the IR radiation absorbed and thus the temperature of the object can be determined.
Image 1: Bimetal thermal sensor
Image 2: Thermo couple
Types: Spot IR Sensors: Measure the temperature on a particular spot of a surface. We are using spot IR sensors for this project. IR scanning systems: Scan larger area. IR thermal imaging cameras: It is basically employs IR temperature sensors to measure temperature from many points over a larger area. The data received is mapped to form a two dimensional image called a thermogram. IR sensors have lesser response time and we can obtain patterns from measured values easily. As we are dealing with an open space, it is even more advantageous to use non contact sensors.
Image 3: Thermal image of hot air balloon
3. Literature Review The review of literature is done to understand the theory and basic principles behind the working of the different hardwares and softwares. UART communication is used for the project majorly. The specifications and working of the arduino, sensors and actuators are studied in this section. https://en.wikipedia.org/
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Master/Slave architecture: Master and slave is a type of protocol used for communication, where one (or more) device(s) (called master) controls one or more set of devices (called slaves) and its processes. The master and slave relationship is established in the beginning of the program and throughout the process of the running the program the master will decide the flow of data and signals. In most of the cases the master will act as the primary device and the secondary devices will be the slaves. In the current project Arduino Mega 2560 is acting as the master and the MLX 60914 IR sensors and the MG995 Tower Pro servo motor acts as slave in the system. The sensors are connected to the Master (Arduino microcontroller) using UART. Arduino Mega has provision to connect 4 analog devices, ie. it can have 4 slaves or secondary devices connected to it.
UART Communication: Universal Asynchronous Receiver/Transmitter (UART) is a physical circuit in a microcontroller or a stand-alone IC which can receive and transmit serial data. This is done using two wires to each of the actuators ie. Tx for transmission of signal and Rx as return wire. This is unlike SPI and I2C communication protocols where there is a clock signal to synchronise the signals. This is used widely in simple systems where two components communicate with each other through transmitter and receiver wires. Thus the Tx of the transmitting device has to be connected to the Rx of the receiving device. The signal begin with a Start bit, and the incoming signals are read at the specific baud rate (frequency of signals predetermined for both the components). Baud rate is usually expressed in bits per seconds (bps), which is the speed at which the signals are sent or received. Thus both the components (UARTs) have to be configured to the predetermined Baud rate. The actuators are having the baud rate of 9600 bps. The same is coded into the arduino so that UARTs can communicate seamlessly. The advantages of UART communication system are: • It has simple connection where only 2 wires are used. • Clock signal is not required for communication. • Any size of data packets can be used for communication. Just that both the UARTs have to be configured. • Works well with simple microcontrollers. This mode of communication has some disadvantages as well, like: • The data transmission is limited to a maximum size of 9 bits. • Multiple slave or multiple masters are not possible to connect as this is a point to point connection.
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The transmitting UART receives the data in parallel from the data bus.
The transmitting UART adds the start bit, parity bit, and the stop bit(s) to the data frame:
The entire packet is sent serially from the transmitting UART to the receiving UART. The receiving UART samples the data line at the pre-configured baud rate:
The receiving UART discards the start bit, parity bit, and stop bit from the data frame:
The receiving UART converts the serial data back into parallel and transfers it to the data bus on the receiving end: Image 4:  UART communication GROUP 4
http://www.circuitbasics.com/basics-uart-communication/
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Arduino Mega (ATmega2560): Arduino Mega 2560 is used for programming the sensors, reading the temperature data from the sensors and for programming the servo motor for rotation control. The baud rate is set to be 9600 bps. The temperature sensors are connected to the analog ports of the arduino and the servo motor is connected to the digital pin of the board. The microcontroller (ATmega2560), can be programmed by arduino programming language. It is used to control the servo motor and the 3 IR sensors mounted at different heights. It receives inputs from IR sensors.
Micro controller Operating voltage Input voltage Input Voltage (limits) Digital I/O pins Analog input pins DC current per I/O pin DC current for 3.3V pin Flash memory SRAM EEPROM Clock speed
ATmega2560 5V 7-12V 6-20V 54 (14 provide PWM outputs) 16 40mA 50mA 256KB 8KB 4KB 16MHz
Table 1: Specification for Arduino Mega2560
Arduino Pro Mini 3.3V:
Image 5: Arduino AT Mega2560
Promini has pins on three out of its four sides. Shorter side pins are used for programming and the other two sides are for Power and GPIO pins. And the three power pins are a Ground, a VCC, and a RAW. Raw is the voltage that is input into the regulator. So it has to be between 3 and 12V. VCC voltage is directly sent to Promini. So it should be below 3.3V. The Pro Mini is not used in the final setup.
Microcontroller Input voltage range Operating voltage range Digital I/O pins DC current per I/O pin PWM pins UART I2C SPI Analog input pins Clock speed
AT Mega 328 3.35-12V 3.3V 14 40mA 6 1 1 1 6 8MHz
Table 2: Specification for Arduino Pro Mini
Image 6: Arduino ProMini https://www.arduino.cc/en/Main/ArduinoBoard
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Servo motor (MG995):
The Servo motor by Tower Pro is used for the project. There are two types- which is position controlled and the other one where the rotation is controlled. The motor used for prototype is rotation control type, works based on the angle of rotation. This motor has a 30cm wire and 3-pin ‘S’ type female header connector. The motor can be controlled using relevant servo codes or libraries and thus regulate the rotation of servo motor by ‘x’ degrees. This motor has a Stable and shock-proof double ball bearing design. Weight Dimensions Operating Voltage Operating Speed Stall Torque Dead band width Temperature Range
55gm 40.7 * 19.7* 42.9 mm 4.8V to 7.2V 0.2s/60º (4.8V), 0.16s/60º(6V) 8.5kgf-cm (4.8V), 10kgf-cm(6V) 5μs 0º - 55ºC
Table 3: Specification for servo motor
IR Sensor (MLX90614)
Image 7: Servo motor MG995
The MLX90614 is used for non contact temperature measurements. It has standard I2C interface with 2x pull up resistors. Dimensions Operating Voltage Operating Current Communication protocol Sensor working temperature Temperature Range
11mm x 17mm 3V - 5V 2mA I2C -40º - +125ºC -70º - +380ºC
Image 8: IR sensor MLX90614
Table 4: Specification for IR sensor
Jumper wires It has male to female DuPont jumper wires to make all connections in the circuit to join the headers on controller boards and sensors
Power Adaptor The end of the AC power adaptor is opened to power up the components via bread board. Model Type Cable Type Connector Input Output Regulation Efficiency Table 5: Specification for Power adaptor GROUP 4
Image 9: Jumper wire
KSAD0550220W1UV-1 AC adaptor US 2- pin plug 100 – 240 V AC 50/60Hz 5.5 DC, 2.2A ≤2% ≥80%
Image 10: Power supply adapter
https://www.sparkfun.com/datasheets/Sensors/Temperature/mlx90614.pdf
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4. Methodolgy The different stages included in the development of design and the execution of the project are described in the figure below. The initial literature study and review was conducted before the start of the model development. The execution of the code was done separately for the sensor data reading and the servo motor rotation. Later the codes were combined and modified to restrain the rotation of servo motor to a single rotation. Matplotlib was used to plot the graphs from the sensor data, which is saved to the .csv file.
Relevance
Master slave UART
Scope and Limitation Stage 1 Background Data Collection
Hardware and software
Arduino microcontroller IR sensors Servo motor
Stage 2 Literature Review
Stage 3 Design
Design of program for sensors Design of program for sevo motor
Product dimensions Ergonomics Flexibility
Stage 4 Programming for Components
Programming for data aquisition
Stage 5 Final Design
Combining and debugging code
Ideas for product development
Building the prototype
Application in smart building systems
Matlab for visualization
Improvizing the setup for optimal performance
Stage 6 Application and Future Scope
Image 11: Methodology Chart GROUP 4
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5. Design of Experiment The design of the prototype is done such that the servo motor can rotate at 360 degrees, with the sensors reading the radiant temperature at 10 degree interval. The program is done in such a manner that there is a delay of 1 second ar each position for the reading to be taken properly.
Design Considerations Work Plane The design of prototype is done to measure the temperature at 3 different heights. The height at which the measurements are taken has a lot of importance as the application of this setup highly depends on that. The further scope explains the design which can be developed for a much flexible application. At a lower workplane, this setup can be used to detect the occupancy of the room. This setup will measure the instantaneous radiant temperature from people, equipments, appliances, and openings. At a higher elevation, where there are no obstructions in the interior of the room, this setup can be used to measure the radiant temperature and can be used as the signal to control shading devices, automated blinds, etc.
Range and accuracy The prototype is designed with cost effective components which have limited range and accuracy. Also the infrared sensor range from which it can sense the radiations may affect the serial data output. The servo motor is having an inertia which is causing miniml error in the angle or rotation.
Hardware design The prototype hardware setup was made using two rectangular boxes. The base rectangular cardboard box contains the Arduino Mega 2560, MG995 Tower Pro servo motor, bread board and the connection to the external power source. This design is prepared so that the whole setup can be placed at any point in a room and it can read the thermal measurements for different angles and contour maps can be plotted.
Image 12: Prototype photograph GROUP 4
Image 13: Prototype photograph 9
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Image 14: Prototype 3D model
Image 15: Prototype 3D model structure GROUP 4
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Circuit and connectivity Both the Servo motor (Tower Pro MG995) and the 3 IR sensors (MLX 90614) are programmed with the same Arduino Mega 2560. This is done for synchronising the rotation of servo motor and the readings from the sensors. Also the hardware will become much more compact when all the actuators are connected to the same microcontroller.
+
AC adapter
IR Sensor 1
_
IR Sensor 2 Bread Board
IR Sensor 3
Servo motor
Computer Image 16:  Circuit Diagram GROUP 4
Arduino AT Mega2560 Adapted from https://www.arduino.cc/en/Tutorial/Sweep
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Coding The program is coded using the Arduino IDE software. This software uses C language for the programming. There are two funtions setup and loop default in the software. We are using only the Setup function in this project as we want the motor to stop after one complete rotation. int servopin = 12; int pos; void setup() { // initialize both serial ports: pinMode(servopin, OUTPUT); Serial.begin(9600); Serial1.begin(9600); Serial2.begin(9600); Serial3.begin(9600); Serial.println(“...”); pos = 50; int i; //if (pos > 2500) pos=500; for (i=0; i < 36; i++) { digitalWrite(servopin, HIGH); delayMicroseconds(9450); digitalWrite(servopin, LOW); delayMicroseconds(9450); //pos+=50;
// read from port 1, send to port 0; if (Serial1.available()) {
}
Serial.print(“S1 “); while(1) { int inByte = Serial1.read(); Serial.write(inByte); if (inByte == ‘\n’) break; }
// read from port 2, send to port 0: if (Serial2.available()) { GROUP 4
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}
}
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Serial.print(“S2 “); while(1) { int inByte = Serial2.read(); Serial.write(inByte); if (inByte == ‘\n’) break; }
// read from port 3, send to port 0: if (Serial3.available()) { Serial.print(“S3 “); while(1) { int inByte = Serial3.read(); Serial.write(inByte); if (inByte == ‘\n’) break; } } delay(1000); }
void loop() { } The cleaning of data obtained from the serial monitor readings was done using python program, where the prefix of ‘T’ and suffix of ‘C’ was removed from the data. Also to extract the relevant data only, checking is done for the length of the string in each of the line and of there are error the last 7 letters are taken for the plotting of data infile = “trial.txt” outfile = “clean.txt” delete_list = [“[2018-04-08 17:57:31.870]”,”[2018-04-08 17:57:31.876]”,”T”,”C”] fin = open(infile) fout = open(outfile,”w+”) for line in fin: for word in delete_list: line = line.replace(word, “”) fout.write(line) fin.close() fout.close() GROUP 4
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Sorting of the data from a single list to separate lists for the three sensors are using code in python language. The text file is taken as input and is sorted to separate lists which can be used for plotting the graph filename = ‘clean.txt’ s1 = list() s2 = list() s3 = list() with open(filename) as file_object: for line in file_object: if “S1” in line : line = line.replace(“S1”,””) s1.append(float(line.strip())) elif “S2” in line : line = line.replace(“S2”,””) s2.append(float(line.strip())) elif “S3” in line : line = line.replace(“S3”,””) s3.append(float(line.strip())) print(s1) print(s2) print(s3) “”” removes values out of range””” for i in s1 : if i > 100 : k = s1.index(i) j = i % 100 print (j) s1[k] = j for i in s2 : if i > 100 : k = s2.index(i) j = i % 100 print (j) s2[k] = j
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for i in s3 : if i > 100 : k = s3.index(i) j = i % 100 print (j) s3[k] = j
print(s1) print(s2) print(s3) The coding for plotting the graph is done using Matplotlib, which uses python language for programming mathematical functions. The code for developing the plot is given below. import numpy as np from mpl_toolkits.mplot3d import axes3d import matplotlib.pyplot as plt fig = plt.figure() ax = fig.add_subplot(111, projection=”3d”) X, Y = np.mgrid[-1:1:30j, -1:1:30j] Z = np.sin(np.pi*X)*np.sin(np.pi*Y)
ax.plot_surface(X, Y, Z, cmap=”autumn_r”, lw=0, rstride=1, cstride=1) ax.contour(X, Y, Z+1, 10, lw=3, colors=”k”, linestyles=”solid”) plt.show()
6. Discussion and Observation Execution The execution of the experiment is done with the harware connected to the computer and external power source. Arduino acts as the master in the circuit which gives the control signal to the servo motor and the three sensors, as well as recieve radiant temperature data from the sensors simultaneously. GROUP 4
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S1 IR Sensor Start S2 IR Sensor Servo motor
Arduino S3 IR Sensor
Data
Manual error checking
Error
Correction
Error free
Plotting
End
Image 17: Logic diagram for data flow
Serial output The IR sensors are provided with micro controllers already attatched to them, which can convert IR radiation data into radiant temperature. These data are recieved at real time on the serial monitor, which can be simultaneosly logged onto a serial logging software called tera term. These serial data can be saved into any file format like .txt, .log, .csv etc.
Isotherm plots The data from the sensors are processed using python program. The program extracts the temperature data alone from the format obtained from the sensors. This formatted data is sorted into three lists corresponding to the three sensor elevations (S1, S2 and S3).
Serial data developed plot S3
29.5-30
30-30.5
30.5-31
S1
350
340
330
320
310
300
290
280
270
260
250
240
230
220
210
200
190
180
170
160
150
140
130
120
110
90
100
80
70
60
50
40
30
20
10
S2
31-31.5
Image 18: Serial data plot GROUP 4
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7. Costing The prototype setup design is done in a very economical way. The sensors and the other components used are widely available in the market. The hardware design is done using light weight-biodegadable materials like chopsticks, cardboard and paper. The cost analysis for the setup is shown in Table 5. Component
Number
Unit cost
Total cost
Arduino Mega
1
1,500
1,500
IR Sensor
3
750
2250
Servo Motor
1
300
300
Jumper Wires
20
7
140
Power Supply Adapter
1
400
400
Other materials (cardboard, thermocol sheet etc.)
1
15
15
Total Cost
Rs. 4605.00
Table 6: Estimation and costing calculations
8. Conclusion The design and execution of the project helped to get an insight into the vast possibilities in the area of smart building, where the small microcontrollers can be used effectively for the better utilisation of energy and smart control of the building. These systems if developed properly can be used for better utilisation of energy and lesser pollution of environment. These can be used to control the air conditioning load, or to control some of the controllable passive design techniques like shading devices or automated blinds. Usage of systems like these can be very cost effective to be installed in small buildings, where building management systems can have a great impact considering the large number of partially air-conditioned buildings in India. Especially for the flourishing amount of high rise office buildings coming up in the growing urban landscape of the country.
9. Future Scope The system is just a glimpse of the immense possibilities for a smart HVAC system, if incorporated can deliver an energy efficient and comfortable built environment. The system must be used to give inputs and feedbacks to the HVAC system which will provide data to the heating and cooling systems about the envelope of the room in which this system is placed in.
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The immediate future scope lies in the limitations which we have undergone, some of which are as listed below. • Network connections • Internet of Things • Instantaneous feedback via mobile devices • Accuracy of servo motor • Range of IR sensors • Obstructions • Spacing of IR sensors Extended ideas for scope are sketched out as the following figures: • Telescopic design for variable sensor heights • Gear system for accurate angle control • Distance measuring device for simultaneous automatic plan generation
Motor and gear systems
Gear system
Distance measuring device
Telescopic shaft
Image 19: Dynamo parametic model
The telescopic design for varying heights of the sensors is developed and modelled parametrically in Autodesk dynamo. GROUP 4
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10. References [1] http://www.circuitbasics.com/basics-uart-communication/ (07 April, 2018-17:00) [2] https://www.arduino.cc/en/Tutorial/Sweep (07 April, 2018-17:30) [3] https://www.sparkfun.com/datasheets/Sensors/Temperature/mlx90614.pdf (07 April, 2018-17:40) [4] https://www.arduino.cc/en (07 April, 2018-17:50)
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