Monday, 30 November 2015
The Internet of Things (IoT): Wireless Gesture-Controlled Robot
The Internet of Things (IoT): Wireless Gesture-Controlled Robot: Wireless Gesture-Controlled Robot (IoT) In this project we are going to control a robot wirelessly using hand gestures. This is an e...
Smoke, Alcohol and LPG-Detection Alarm
Smoke, Alcohol and LPG-Detection Alarm
Presented
here is a circuit for raising an alarm on detecting smoke or LPG
cooking gas leakage, or even alcohol vapours in breath. This is achieved
by using a basic unit with different sensors for smoke, LPG and
alcohol. So, different alarms can be made by simply changing the input
sensor.
Circuit and working
Fig. 1 shows circuit diagram of the smoke alarm. The basic unit employs dual op-amp LM358 (IC1), transistor T1 and timer NE555 (IC2), configured in astable mode. Selection of MQ* sensor is based on the purpose for which the alarm circuit is being designed. For the smoke alarm circuit, you will need MQ2 sensor. Similarly, for detection of alcohol, MQ3 sensor is used, while MQ6 sensor is used for detecting LPG cooking gas.
MQ* sensor has six pins. Heater filament, between pins H-H, is directly connected to 5V and ground. Two sets of input/output (I/O) pins A-A and B-B are present. Select any one set for input to the basic unit. Arrangement of pins is shown in Fig. 1.
IC1
is wired in the non-inverting comparator mode. The reference voltage is
applied to inverting input (IN1-) and the voltage to be compared is
applied to non-inverting input (IN1+). Whenever voltage to be compared
(IN1+) goes above reference voltage (IN1-), output of the op-amp swings
to high, and vice-versa. The alarm circuit is built around NE555. The
frequency of the astable multivibrator is dependent on the values of
resistors R4 and R5, and capacitor C2.
After connecting to 5V supply, wait for about ten seconds for the filament to heat properly. Adjust 10k potmeter (VR1) till the alarm stops sounding.
Under normal conditions (that is, no fumes from LPG or no alcohol in breath near MQ*), output of IC1 at pin 1 remains low. As a result, transistor T1 does not conduct, which makes pin 4 of IC2 low. It keeps timer NE555 on reset. There is no output at pin 3 of IC2, and no sound comes out of the speaker.
On the other hand, when there are fumes from LPG, or there is alcohol in breath near MQ*, output of IC1 at pin 1 goes high. As a result, transistor T1 drives into saturation and its emitter goes high. Pin 4 of IC2 also goes high. The timer goes into astable mode, producing pulsed wave at output at pin 3 of IC2, which is coupled to speaker LS1 through coupling capacitor C4, and an alarm is set on.
Construction and testing
An actual-size, single-side PCB for the alarm is shown in Fig. 2 and its component layout in Fig. 3. Enclose the PCB in a suitable box, in such a way that fumes can circulate near MQ* sensor easily. Ensure proper wiring to avoid any errors. Before using the circuit, use MQ3 sensor to verify test points given in the table.
 |
Circuit and working
Fig. 1 shows circuit diagram of the smoke alarm. The basic unit employs dual op-amp LM358 (IC1), transistor T1 and timer NE555 (IC2), configured in astable mode. Selection of MQ* sensor is based on the purpose for which the alarm circuit is being designed. For the smoke alarm circuit, you will need MQ2 sensor. Similarly, for detection of alcohol, MQ3 sensor is used, while MQ6 sensor is used for detecting LPG cooking gas.
MQ* sensor has six pins. Heater filament, between pins H-H, is directly connected to 5V and ground. Two sets of input/output (I/O) pins A-A and B-B are present. Select any one set for input to the basic unit. Arrangement of pins is shown in Fig. 1.
 Fig. 1: Circuit diagram of the alarm circuit |
 |
After connecting to 5V supply, wait for about ten seconds for the filament to heat properly. Adjust 10k potmeter (VR1) till the alarm stops sounding.
Under normal conditions (that is, no fumes from LPG or no alcohol in breath near MQ*), output of IC1 at pin 1 remains low. As a result, transistor T1 does not conduct, which makes pin 4 of IC2 low. It keeps timer NE555 on reset. There is no output at pin 3 of IC2, and no sound comes out of the speaker.
On the other hand, when there are fumes from LPG, or there is alcohol in breath near MQ*, output of IC1 at pin 1 goes high. As a result, transistor T1 drives into saturation and its emitter goes high. Pin 4 of IC2 also goes high. The timer goes into astable mode, producing pulsed wave at output at pin 3 of IC2, which is coupled to speaker LS1 through coupling capacitor C4, and an alarm is set on.
 Fig. 2: Actual-size PCB pattern of the alarm circuit |
 Fig. 3: Component layout of the PCB |
Construction and testing
An actual-size, single-side PCB for the alarm is shown in Fig. 2 and its component layout in Fig. 3. Enclose the PCB in a suitable box, in such a way that fumes can circulate near MQ* sensor easily. Ensure proper wiring to avoid any errors. Before using the circuit, use MQ3 sensor to verify test points given in the table.
Sunday, 29 November 2015
eBooks On Control System
35 Free eBooks On Control System
Here's bringing 35 absolutely free ebooks to help you with all you ever wanted to learn about various control systems. Have fun!Atithya Amaresh
Author: Derek P. Atherton
Publisher: Bookboon, 2013
The book aims to provide both worked examples and additional problems with answers. A major objective is to enable the reader to develop confidence in analytical work by showing how calculations can be checked using Matlab/Simulink.
2. Control Theory with Applications to Naval Hydrodynamics
Author: R. Timman, 1975
The lectures present an introduction to modern control theory. Calculus of variations is used to study the problem of determining the optimal control for a deterministic system without constraints and for one with constraints.
3. Stochastic Systems: Estimation, Identification and Adaptive Control
Author: P.R. Kumar, Pravin Varaiya
Publisher: Prentice Hall, 1986
This book is concerned with the questions of modeling, estimation, optimal control, identification, and the adaptive control of stochastic systems. The treatment is unified by adopting the viewpoint of one who must make decisions under uncertainty.
4. Stochastic Modeling and Control
Author: Ivan Ganchev Ivanov (ed.)
Publisher: InTech, 2012
The book provides a self-contained treatment on practical aspects of stochastic modeling and calculus including applications in engineering, statistics and computer science. Readers should be familiar with probability theory and stochastic calculus.
5. Frontiers in Advanced Control Systems
Author: Ginalber Luiz de Oliveira Serra (ed.)
Publisher: InTech, 2012
This book brings the state-of-art research results on advanced control from both the theoretical and practical perspectives. The fundamental and advanced research results and technical evolution of control theory are of particular interest.
6. Lectures on Stochastic Control and Nonlinear Filtering
Author: M. H. A. Davis
Publisher: Tata Institute of Fundamental Research, 1984
There are actually two separate series of lectures, on controlled stochastic jump processes and nonlinear filtering respectively. They are united however, by the common philosophy of treating Markov processes by methods of stochastic calculus.
7. An Introduction to Nonlinearity in Control Systems
Author: Derek Atherton
Publisher: BookBoon, 2011
The book is concerned with the effects of nonlinearity in feedback control systems and techniques which can be used to design feedback loops containing nonlinear elements. The material is of an introductory nature but hopefully gives an overview.
8. Applications of Nonlinear Control
Author: Meral Altinay
Publisher: InTech, 2012
A trend of investigation of Nonlinear Control Systems has been present over the last few decades. This book includes topics such as Feedback Linearization, Lyapunov Based Control, Adaptive Control, Optimal Control and Robust Control.
9. Discrete-Event Control of Stochastic Networks: Multimodularity and Regularity
Author: Eitan Altman, Bruno Gaujal, Arie Hordijk
Publisher: Springer, 2003
Opening new directions in research in stochastic control, this book focuses on a wide class of control and of optimization problems over sequences of integer numbers. The theory is applied to the control of stochastic discrete-event dynamic systems.
10. Advanced Model Predictive Control
Author: Tao Zheng
Publisher: InTech, 2011
Model Predictive Control refers to a class of control algorithms in which a dynamic process model is used to predict and optimize process performance. From lower request to complicated process plants, MPC has been accepted in many practical fields.
11. Control and Nonlinearity
Author: Jean-Michel Coron
Publisher: American Mathematical Society, 2009
This book presents methods to study the controllability and the stabilization of nonlinear control systems in finite and infinite dimensions. Examples are given where nonlinearities turn out to be essential to get controllability or stabilization.
12. Discrete Time Systems
Author: Mario Alberto Jordan
Publisher: InTech, 2011
This book covers the wide area of Discrete-Time Systems. Their contents are grouped conveniently in sections according to significant areas, namely Filtering, Fixed and Adaptive Control Systems, Stability Problems and Miscellaneous Applications.
13. PID Control: Implementation and Tuning
Author: Tamer Mansour
Publisher: InTech, 2011
The PID controller is considered the most widely used controller. It has numerous applications varying from industrial to home appliances. This book is an outcome of contributions and inspirations from many researchers in the field of PID control.
14. Chaotic Systems
Author: Esteban Tlelo-Cuautle
Publisher: InTech, 2011
This book presents a collection of major developments in chaos systems covering aspects on chaotic behavioral modeling and simulation, control and synchronization of chaos systems, and applications like secure communications.
15. Control Theory: From Classical to Quantum Optimal, Stochastic, and Robust Control
Author: M.R. James
Publisher: Australian National University, 2005
These notes are an overview of some aspects of optimal and robust control theory considered relevant to quantum control. The notes cover classical deterministic optimal control, classical stochastic and robust control, and quantum feedback control.
16. Distributed Control of Robotic Networks
Author: Francesco Bullo, Jorge Cortes, Sonia Martinez
Publisher: Princeton University Press, 2009
This introductory book offers a distinctive blend of computer science and control theory. The book presents a broad set of tools for understanding coordination algorithms, determining their correctness, and assessing their complexity.
17. Linear Matrix Inequalities in System and Control Theory
Author: S. Boyd, L. El Ghaoui, E. Feron, V. Balakrishnan, 1997
The authors reduce a wide variety of problems arising in system and control theory to a handful of optimization problems that involve linear matrix inequalities. These problems can be solved using recently developed numerical algorithms.
18. Nonlinear System Theory: The Volterra/Wiener Approach
Author: Wilson J. Rugh
Publisher: The Johns Hopkins University Press, 1981
Contents: Input/Output Representations in the Time and Transform Domain; Obtaining Input/Output Representations from Differential-Equation Descriptions; Realization Theory; Response Characteristics of Stationary Systems; Discrete-Time Systems; etc.
19. Linear Controller Design: Limits of Performance
Author: Stephen Boyd, Craig Barratt
Publisher: Prentice-Hall, 1991
The book is motivated by the development of high quality integrated sensors and actuators, powerful control processors, and hardware and software that can be used to design control systems. Written for students and industrial control engineers.
20. High Performance Control
Author: T.T. Tay, I.M.Y. Mareels, J.B. Moore
Publisher: Birkhauser, 1997
Using the tools of optimal control, robust control and adaptive control, the authors develop the theory of high performance control. Topics include performance enhancement, stabilizing controllers, offline controller design, and dynamical systems
21. Systems Structure and Control
Author: Petr Husek
Publisher: InTech, 2008
The the book covers broad field of theory and applications of many different control approaches applied on dynamic systems. Output and state feedback control include among others robust control, optimal control or intelligent control methods.
22. Control Engineering: An introduction with the use of Matlab
Author: Derek Atherton
Publisher: BookBoon, 2009
The book covers the basic aspects of linear single loop feedback control theory. Explanations of the mathematical concepts used in classical control such as root loci, frequency response and stability methods are explained by making use of MATLAB.
23. The Analysis of Feedback Systems
Author: Jan C. Willems
Publisher: The MIT Press, 1971
This monograph develops further and refines methods based on input -output descriptions for analyzing feedback systems. Contrary to previous work in this area, the treatment heavily emphasizes and exploits the causality of the operators involved.
24. A Course in H-infinity Control Theory
Author: Bruce A. Francis
Publisher: Springer, 1987
An elementary treatment of linear control theory with an H-infinity optimality criterion. The systems are all linear, timeinvariant, and finite-dimensional and they operate in continuous time. The book has been used in a one-semester graduate course.
25. Feedback Control Theory
Author: John Doyle, Bruce Francis, Allen Tannenbaum, 1990
The book presents a theory of feedback control systems. It captures the essential issues, can be applied to a wide range of practical problems, and is as simple as possible. Addressed to students who have had a course in signals and systems.
26. Constructive Nonlinear Control
Author: R. Sepulchre, M. Jankovic, P. Kokotovic
Publisher: Springer, 1996
Several streams of nonlinear control theory are directed towards a constructive solution of the feedback stabilization problem. Analytic, geometric and asymptotic concepts are assembled as design tools for a wide variety of nonlinear phenomena.
27. Fuzzy Control
Author: K. M. Passino, S. Yurkovich
Publisher: Addison Wesley, 1997
Introduction to fuzzy control with a broad treatment of topics including direct fuzzy control, nonlinear analysis, identification/ estimation, adaptive and supervisory control, and applications, with many examples, exercises and design problems.
28. An Introduction to Intelligent and Autonomous Control
Author: P. J. Antsaklis, K. M. Passino
Publisher: Springer, 1992
Introduction to the area of intelligent control by leading researchers in the area. Approaches to intelligent control, including expert control, planning systems, fuzzy control, neural control and learning control are studied in detail.
29. Adaptive Control
Author: Kwanho You
Publisher: InTech, 2009
This book discusses the issues of adaptive control application to model generation, adaptive estimation, output regulation and feedback, electrical drives, optical communication, neural estimator, simulation and implementation.
30. Mathematical Control Theory: Deterministic Finite Dimensional Systems
Author: Eduardo D. Sontag
Publisher: Springer, 1998
This textbook introduces the basic concepts of mathematical control and system theory in a self-contained and elementary fashion. Written for mathematically mature undergraduate or beginning graduate students, as well as engineering students.
31. Adaptive Control: Stability, Convergence, and Robustness
Author: Shankar Sastry, Marc Bodson
Publisher: Prentice Hall, 1994
The book gives the major results, techniques of analysis and new directions in adaptive systems. It presents deterministic theory of identification and adaptive control. The focus is on linear, continuous time, single-input single output systems.
32. Feedback Systems: An Introduction for Scientists and Engineers
Author: Karl J. Astrom, Richard M. Murray
Publisher: Princeton University Press, 2008
An introduction to the basic principles and tools for the design and analysis of feedback systems. It is intended for scientists and engineers who are interested in utilizing feedback in physical, biological, information and social systems.
33. Control in an Information Rich World
Author: Richard M. Murray
Publisher: Society for Industrial Mathematics, 2002
The prospects for control in the current and future technological environment. The text describes the role the field will play in commercial and scientific applications over the next decade, and recommends actions required for new breakthroughs.
34. Control Systems
Author: Andrew Whitworth
Publisher: Wikibooks, 2006
An inter-disciplinary engineering text that analyzes the effects and interactions of mathematical systems. This book is for third and fourth year undergraduates in an engineering program. It considers both classical and modern control methods.
35. Dynamic System Modeling and Control
Author: Hugh Jack, 2005
Dynamic System Modeling and Control introduces the basic concepts of system modeling with differential equations. Supplemental materials at the end of this book include a writing guide, summary of math topics, and a table of useful engineering units.
Tuesday, 24 November 2015
Let us Build RF-Controlled Aircraft
RF-Controlled Aircraft
Somnath Bera
Presented here is a remote-controlled aircraft project based on Arduino and 433MHz RF modules controlling a brushless DC motor and three servo motors. It comprises an Arduino-based remote control at the transmitter’s end and an Arduino-based aircraft at the receiver’s end. The aim of this project is to develop a 4-channel wireless control system.
Controlling multiple servo motors using XBee RF modules is very sophisticated and robust but a bit costlier. For cheaper solution, we used a pair of simple 433MHz RF transmitter and receiver modules.
Circuit and working
Fig.
1 shows the circuit diagram of an RF-controlled aircraft’s transmitter
side and Fig. 2 shows the circuit diagram of the receiver side. The
circuits are built around Arduino
Uno (board1 and board2), a pair of 433MHz RF modules (TX1 and RX1), ESC
(electronic speed controller) module, three servo motors (M1-M3), a
BLDC motor (M4) and a few other components.
The transmitter’s side is driven by a 9V PP3 battery and the receiver’s side by an 11.1V LiPo battery, which is used to power the brushless DC motor (BLDC motor) through the ESC module.
The Arduino board1 receives power supply from the 9V PP3 battery and Arduino board2 from the 11.1V battery at their respective Vin input pins.
There are four potentiometers on the transmitter’s side which are used for sending different control signals to the receiver’s side through the RF modules. The control signals received by the receiver are processed by the microcontroller in the Arduino, which in turn controls the BLDC motor, the servo motors for rudder, aileron and elevator of the aircraft.
Arduino Uno board. Arduino is an open source electronics prototyping platform based on flexible, easy-to-use hardware and software. It is intended for artists, designers, hobbyists and anyone interested in creating interactive objects or environments.
Arduino
Uno is a board based on ATmega328 microcontroller. It comprises 14
digital input/output (I/O) pins, six analogue inputs, a USB connection
for programming the on-board microcontroller, power jack, an ICSP header
and a reset button.
It is operated with a 16MHz crystal oscillator and contains everything needed to support the microcontroller. It is very easy to use as the user simply needs to connect it to a computer with a USB cable, or power it with an AC-to-DC adaptor or battery to get it started. The microcontroller on the board is programmed using Arduino programming language and Arduino development environment.
433MHz RF modules. These are inexpensive radios that operate at 433MHz frequency (refer Fig. 3). These radios are available in a separate transmitter and receiver or a single transceiver model. The operating voltage for transmitter is from 1.5V to 12V and for the receiver is from 3V to 5V. The range of transmission is 30m to 150m depending on the voltage supply and the type of module used.
Transmitter’s side. Pin 12 of board1 is connected with data pin 2 of RF transmitter (TX1). Pin A0 through A3 of board1 are connected with four 10k presets (VR1 throughVR4). VR1, VR2, VR3 and VR4 are used to control BLDC (refer Fig. 4), rudder, aileron and elevator, respectively.
Receiver’s side.
Pin 11 of board2 is connected with data pins (6 and 7) of RF receiver
(RX1). The pins 12, 10, 8 and 9 of the board are connected with the
signal pin of M1 (elevator), M2 (rudder), M3 (aileron) servo motors and
ESC module (refer Fig. 5), respectively. Some of the main body parts of a
typical RC aircraft are shown in Fig. 6.
BLDC motor is used as the propeller system of the aircraft. The propeller or airscrew converts rotary motion from the motor to provide propulsive force. It is the most important part of the aircraft. The propeller is mounted on the front side of the aircraft.
A rudder is used to steer the aircraft that moves through the air medium, controlling the direction in which the aircraft is pointing. It is a flat plane or sheet of material attached with hinges to the craft’s stern, tail or after end.
An aileron is a hinged flight-control surface usually attached to the trailing edge of each wing of an aircraft. Ailerons are used in pairs to control the aircraft in roll, or movement around the aircraft’s longitudinal axis.
Elevators are flight control surfaces, usually at the rear of an aircraft, which control the aircraft’s longitudinal altitude. The position of the elevator controls whether the nose of the airplane is pointing up or down and thus moving up or down. The elevators are usually hinged to a fixed or adjustable rear surface.
Input supply wire of ESC is connected with an 11.1V battery. Three output wires of ESC are connected with three phase inputs of BLDC motor (M4).
Software
The software of this project is written in Arduino programming language. The Arduino UNO is programmed using Arduino IDE software. ATmega328 on Arduino UNO comes with a boot loader that allows you to upload a new code to it without the use of an external hardware programmer. It communicates using the STK500 protocol.
You can also bypass the boot loader and program the microcontroller through in-circuit serial programming (ICSP) header, but using boot loader programming is quick and easy. Select the correct board from ‘Tools → Board’ menu in Arduino IDE and burn the program (sketch) through a standard USB port in the computer.
Add library ‘SoftwareServo’ in the libraries folder (arduino-0022\libraries) of Arduino IDE before compiling the sketch.
We have used red brick ESC module. If you use any other ESC module, you may be required to modify the delays in the code accordingly.
Construction and testing
An actual-size, single-side PCB for the RF-controlled aircraft transmitter circuit is shown in Fig. 7 and its component layout in Fig. 8. The PCB for the receiver circuit is shown in Fig. 9 and its component layout in Fig. 10.
PCBs of transmitter and receiver are in the form of shields, so mount these PCBs on top of the respective Arduino UNO board. Connect 9V battery to the transmitter’s side and 11.1V battery to the receiver’s side. Check the working of BLDC motor by varying VR1, servo motor M1 using VR4, servo motor M2 using VR2 and servo motor M3 using VR3. If there is any problem, verify the test points given in the table. Once this is done, it is time to build the body of the aircraft.
Building a remote-controlled (RC) aircraft requires some basic skills and creativity. There are some rich tutorials available on the Internet.
Some information to build your own RC aircraft can be found from these links:
http://www.easyrc.com/airplanes/
http://rcvehicles.about.com/od/diyaircraft/
http://www.stenulson.net/rcflight/rcflight.htm
You can either build the body of the aircraft by yourself or get it from an electronics spare parts shop. The receiver PCB along with the 11.1V battery should be mounted properly on the aircraft. Now, your RF-controlled aircraft is ready to fly.
The aircraft can be launched by gathering speed on a long runway or by launching with the use of hands by literally throwing it into the air. In the first case, as soon as your plane builds up enough speed and catches the wind, it will lift from the ground. But note that if the road surface is uneven, or it is covered with grass, your plane might not be able to gather the necessary speed for takeoff. At this point, you should opt for a hand launch.
Since the aircraft is controlled by a remote control it has a finite range. If your plane gets too far (either vertically or horizontally) from the transmitter in your hand, it might lose power. This will send your plane plummeting back to the ground. The usual way to fly it is in a circular pattern above your head.
After assembling all the parts, switch on both the transmitter and receiver circuits. Slowly vary VR1 to increase the speed of the BLDC motor (propeller). Once it takes off above the ground, vary VR2, VR3 and VR4 and observe the flight pattern. Ensure that it does not go beyond 100m distance from the transmitter in your hand. To bring it back to the ground, reduce the speed by varying VR1.
Somnath Bera
Presented here is a remote-controlled aircraft project based on Arduino and 433MHz RF modules controlling a brushless DC motor and three servo motors. It comprises an Arduino-based remote control at the transmitter’s end and an Arduino-based aircraft at the receiver’s end. The aim of this project is to develop a 4-channel wireless control system.
 Fig. 1: Circuit of the RF-controlled aircraft (transmitter’s side) |
Controlling multiple servo motors using XBee RF modules is very sophisticated and robust but a bit costlier. For cheaper solution, we used a pair of simple 433MHz RF transmitter and receiver modules.
Circuit and working
 |
The transmitter’s side is driven by a 9V PP3 battery and the receiver’s side by an 11.1V LiPo battery, which is used to power the brushless DC motor (BLDC motor) through the ESC module.
The Arduino board1 receives power supply from the 9V PP3 battery and Arduino board2 from the 11.1V battery at their respective Vin input pins.
There are four potentiometers on the transmitter’s side which are used for sending different control signals to the receiver’s side through the RF modules. The control signals received by the receiver are processed by the microcontroller in the Arduino, which in turn controls the BLDC motor, the servo motors for rudder, aileron and elevator of the aircraft.
Arduino Uno board. Arduino is an open source electronics prototyping platform based on flexible, easy-to-use hardware and software. It is intended for artists, designers, hobbyists and anyone interested in creating interactive objects or environments.
 Fig. 2: Circuit of the RF-controlled aircraft (receiver’s side) |
 Fig. 3: 433MHz RF modules |  Fig. 4: A brushless DC motor |
It is operated with a 16MHz crystal oscillator and contains everything needed to support the microcontroller. It is very easy to use as the user simply needs to connect it to a computer with a USB cable, or power it with an AC-to-DC adaptor or battery to get it started. The microcontroller on the board is programmed using Arduino programming language and Arduino development environment.
433MHz RF modules. These are inexpensive radios that operate at 433MHz frequency (refer Fig. 3). These radios are available in a separate transmitter and receiver or a single transceiver model. The operating voltage for transmitter is from 1.5V to 12V and for the receiver is from 3V to 5V. The range of transmission is 30m to 150m depending on the voltage supply and the type of module used.
Transmitter’s side. Pin 12 of board1 is connected with data pin 2 of RF transmitter (TX1). Pin A0 through A3 of board1 are connected with four 10k presets (VR1 throughVR4). VR1, VR2, VR3 and VR4 are used to control BLDC (refer Fig. 4), rudder, aileron and elevator, respectively.
 Fig. 5: ESC module |  Fig. 6: Parts of an RC aircraft (courtesy: dduino.blogspot.in) |
 |
BLDC motor is used as the propeller system of the aircraft. The propeller or airscrew converts rotary motion from the motor to provide propulsive force. It is the most important part of the aircraft. The propeller is mounted on the front side of the aircraft.
A rudder is used to steer the aircraft that moves through the air medium, controlling the direction in which the aircraft is pointing. It is a flat plane or sheet of material attached with hinges to the craft’s stern, tail or after end.
An aileron is a hinged flight-control surface usually attached to the trailing edge of each wing of an aircraft. Ailerons are used in pairs to control the aircraft in roll, or movement around the aircraft’s longitudinal axis.
Elevators are flight control surfaces, usually at the rear of an aircraft, which control the aircraft’s longitudinal altitude. The position of the elevator controls whether the nose of the airplane is pointing up or down and thus moving up or down. The elevators are usually hinged to a fixed or adjustable rear surface.
Input supply wire of ESC is connected with an 11.1V battery. Three output wires of ESC are connected with three phase inputs of BLDC motor (M4).
Software
The software of this project is written in Arduino programming language. The Arduino UNO is programmed using Arduino IDE software. ATmega328 on Arduino UNO comes with a boot loader that allows you to upload a new code to it without the use of an external hardware programmer. It communicates using the STK500 protocol.
You can also bypass the boot loader and program the microcontroller through in-circuit serial programming (ICSP) header, but using boot loader programming is quick and easy. Select the correct board from ‘Tools → Board’ menu in Arduino IDE and burn the program (sketch) through a standard USB port in the computer.
 Fig. 7: An actual-size, single-side PCB for the RF-controlled aircraft (transmitter’s side) |  Fig. 8: Component layout for the PCB (transmitter’s side) |
We have used red brick ESC module. If you use any other ESC module, you may be required to modify the delays in the code accordingly.
Construction and testing
An actual-size, single-side PCB for the RF-controlled aircraft transmitter circuit is shown in Fig. 7 and its component layout in Fig. 8. The PCB for the receiver circuit is shown in Fig. 9 and its component layout in Fig. 10.
 Fig. 9: An actual-size, single-side PCB for the RF-controlled aircraft (receiver’s side) |  Fig. 10: Component layout for the PCB (receiver’s side) |
PCBs of transmitter and receiver are in the form of shields, so mount these PCBs on top of the respective Arduino UNO board. Connect 9V battery to the transmitter’s side and 11.1V battery to the receiver’s side. Check the working of BLDC motor by varying VR1, servo motor M1 using VR4, servo motor M2 using VR2 and servo motor M3 using VR3. If there is any problem, verify the test points given in the table. Once this is done, it is time to build the body of the aircraft.
Building a remote-controlled (RC) aircraft requires some basic skills and creativity. There are some rich tutorials available on the Internet.
Some information to build your own RC aircraft can be found from these links:
http://www.easyrc.com/airplanes/
http://rcvehicles.about.com/od/diyaircraft/
http://www.stenulson.net/rcflight/rcflight.htm
You can either build the body of the aircraft by yourself or get it from an electronics spare parts shop. The receiver PCB along with the 11.1V battery should be mounted properly on the aircraft. Now, your RF-controlled aircraft is ready to fly.
The aircraft can be launched by gathering speed on a long runway or by launching with the use of hands by literally throwing it into the air. In the first case, as soon as your plane builds up enough speed and catches the wind, it will lift from the ground. But note that if the road surface is uneven, or it is covered with grass, your plane might not be able to gather the necessary speed for takeoff. At this point, you should opt for a hand launch.
Since the aircraft is controlled by a remote control it has a finite range. If your plane gets too far (either vertically or horizontally) from the transmitter in your hand, it might lose power. This will send your plane plummeting back to the ground. The usual way to fly it is in a circular pattern above your head.
After assembling all the parts, switch on both the transmitter and receiver circuits. Slowly vary VR1 to increase the speed of the BLDC motor (propeller). Once it takes off above the ground, vary VR2, VR3 and VR4 and observe the flight pattern. Ensure that it does not go beyond 100m distance from the transmitter in your hand. To bring it back to the ground, reduce the speed by varying VR1.
Saturday, 21 November 2015
Mesh Network Topology for IoT Applications
Mesh Network Topology for IoT Applications
Network topologies come in different shapes and sizes. Each network topology has its own advantages and implementation areas. While networks of the past have mostly been wired, wireless networks have gained significant traction in the last fifteen odd years. In this article, different network topologies are highlighted with more focus on mesh networks. We will also see how mesh networks fit in the Internet of things (IoT) domain.
Different network topologies
Let us briefly take a look at the different kinds of topologies.
Bus Topology
Ring Topology
Star Topology
Mesh TopologyTerminologies explained in detail
Packets. Data is sent in form of group of bytes. These groups are called packets. Each protocol has a fixed number of bytes per packet. The size of packet affects the performance of the network. A packet is divided into two parts, the header and the body. The header contains the details that are required to identify the packet. It usually contains the source and destination address and gives some indication of what data is contained in the packet. The body of the packet contains the actual data. For instance, in a street lighting scenario, the body would indicate the status of light such as ‘ON’, ‘OFF’ or ‘DIM’.
Hops. When data jumps from one device to another, it is known as data hopping, packet hopping or just hops. These hops decide the range and reliability of the network. Imagine there are five street lights to a gateway device. The data from the first street light hops via other street lights sequentially to reach the gateway.
Nodes. Any device that is going to receive or send a packet is called as a node. A node could be a utility meter, a light, an electrical appliance, a computer or rather anything with the ability to transmit and/ or receive data. A node can be wired or wireless depending upon the network it is in.
How mesh works
A mesh network has every single node connected to multiple nodes. All these nodes transmit packets wirelessly and they are in range of each other. This ensures packets transmitted by one node is received by multiple nodes. The packets received are then forwarded, until they reach their expected destination. As there are multiple copies of the same packet in the network, the chances of the packet reaching its destination are quite high, even if individual nodes in the network fail. The probability of packets reaching their destination is also increased because mesh networks do not have fixed paths for packet hopping. Failure of nodes does not result in the network crashing. A single point of failure can occur if the mesh network works on the coordinator router architecture like the ZigBee network. This means that if the coordinator of a network fails then the whole network crashes and you are back to square one.
Data hopping through one node
Data re-routing after node fails
New nodes can be added to the network without facing hiccups. These nodes add themselves to the network without much effort and begin transmitting and receiving data just like the remaining network. This is the self-forming feature of the mesh network. Adding new nodes does not affect the remaining nodes. However, each protocol has its own limit of nodes that it can handle. For example, the ZigBee mesh can handle around 100 nodes per network.
Mesh implementation comes with advantages…
Self-healing. In case one node malfunctions, the packets re-routes on its own to reach the appropriate destination.End-to-end reach. The range of the mesh can be extended up to multiple kilometers with the use of appropriate algorithms and technology.
Scalable. New nodes can be easily added to the network without disturbing the existing architecture.
Adaptable. The mesh network can be adapted to a wide variety of networks from where we want to get data. This includes networks for home automation, smart lighting, street lighting, smart metering, medical wearables and industrial automation.
…and disadvantages
Architecture. The architecture of the mesh network differs from protocol to protocol. As a result each protocol comes with its own sets of disadvantages. To add to it, most protocols are not interoperable with each other. This results in having to deploy a single mesh and then finding if it suits you or not. For example, the ZigBee mesh has coordinator router architecture. This means that there is one coordinator per network that has multiple routers. On the other hand, the DigiMesh protocol has only routers in the network and there are no coordinators. Needless to say, these two protocols are not interoperable. Each protocol has its own set of benefits and drawbacks.Redundancy. There is a high redundancy in the amount of data that is sent and received in the mesh. Algorithms are needed to effectively manage this redundancy, otherwise it affects the speed of the network. This limits the area of usage of the mesh protocol. For example, sensor or meter data can be collected without much hassle, but audio or video data cannot be transferred by mesh network; at least not the current implementations of mesh network.
Lack of interoperability. Different mesh algorithms do not work with each other. For example, ZigBee protocol will not work with DigiMesh, which will not work with Smartt Mesh. This does not let the same network use different protocols. This means if you have implemented DigiMesh for home automation then you cannot use ZigBee based sensors.
Implementations in IoT
The mesh network can be used in multiple scenarios as talked about in the advantages. Here we will throw light on two completely different scenarios.Let’s take the example of medical wearables. Assume that these are battery operated devices monitoring the patient’s heartbeats. These sensors would be spread across the floor of a hospital, each with a unique ID to identify the patient in question and the data about the heartbeats. A mesh network would help in collecting data and transferring them to a central location to be monitored by a doctor, intern or nurse. Even if the patients moved about on the floor, the data would form new routes and reach the server. A central monitoring station would mean that the person who is monitoring the patients would not have to move about. Also, this data can be backed up on the cloud in order to maintain the history of the patient’s condition. Thus the mesh network now becomes the best method of communication for remote monitoring of patient data.
This is another example for industrial automation. Large industries have a wide variety of human operated or automatic machines that communicate with each other continuously. Needless to say, wiring becomes a huge hassle in industries. To top it off, laying down new wires is an equally tough task. A mesh network can be successfully deployed here in order to enable the machines to communicate wirelessly. High range technology along with repeaters would help in overcoming the solid metal obstacles that would hamper communication. There would be no cost of extra wiring and communication would happen without change of the protocol of the machine. Once again, the status and the data of all the machines could be monitored from a central server. All this data could be uploaded to the cloud in order to give remote monitoring capabilities.
Mesh network will undoubtedly be the future of IoT communication
So, what does this mean for the networking domain in general and the machine to machine (M2M)/IoT field specifically? Mesh network is without a doubt the future of computer networking. The M2M/IoT domain uses a large number of sensors to collect and upload data to the internet. Mesh network is an efficient way to do it. The future will progress in the direction of interoperability and battery efficiency.At the present moment, there is no single standard for mesh network and going forward this will have to change if we are to collect vast amounts of data and upload it on the Internet. As sensors will be battery operated, the power management and energy efficiency part will play a big role in the mesh algorithms of the future. A winning combination of mesh algorithm will be one that can be truly plug-n-play using nothing more that market bought components, replete with collision management algorithms, power management features and user friendly user interface similar to most of the websites on the Internet.
The IoT challenges and the future world
The IoT challenges and the future world ..... !!!
Have a Read ( ያንቡት)
Thousands Of Spots In An Airbus, All Inspected By A Single Device
Industrial
automation has advanced leaps and bounds. We have reached that point
where technology enables one person to do so much more with the same
effort. Where did it start, and what’s up next?
Mr. Rahman Jamal, Global Technology & Marketing Director at National Instruments, speaks to Dilin Anand from EFY.
Q. Every firm seems to have their own in-house term for the IoT paradigm, before “IOT” itself became the buzz word. What’s your favorite?
A. The term I
personally prefer that is primarily used in academia is Cyber-Physical
Systems (CPS). It sounds a bit techy and abstract, but it’s a tangible
term. If you look at it, “cyber” actually points towards “connectedness”
referring to the Internet obviously and “physical” stands for the real
physical world, pointing towards the I/Os, sensors, etc., whereas
“Systems” refers to embedded systems. If you take this term that way
then it becomes absolutely tangible – Internet connecting to the
physical world with the help of embedded systems. The National Science
Foundation and the University of Berkeley coined the term in 2006 and in
the same year when the very first workshop on CPS was conducted our CEO
Dr. James Truchard was invited to deliver a keynote on how to build CPS
with a platform-based design approach called Graphical System Design.
So as you can see we have been involved with this from the very
beginning.
Q. We’ve heard that fabs have
had smart automation since decades. What’s the earliest form of the IoT
that you have personally come across?
A. Now that is a good
point. When I was doing my Master Thesis more than 20 years ago, I
worked in collaboration with Phoenix Contact in Germany on a project
around computer-integrated manufacturing (CIM). Many of the ideas and
visions CIM pursued would be broadly called Industrial IoT today, but
with the difference that at that time the Internet did not exist. So
what they did was they came up with a new bus called field bus to
connect field devices and PLCs to the machines on the factory floor.
From this idea many of the different fieldbuses such as CANbus,
Profibus, Interbus S etc. evolved. So these were more of an “Intranet”
if you will with factory-related proprietary protocols that were used to
connect controllers to intelligent machines. But CIM never really took
off simply because we did not have the Internet at that time.
Q. What is the biggest challenge that is being faced here?
A. If you look at your
cell phone, you have many different vendors like Apple, Samsung,
Microsoft, Sony, HTC and others, but the devices can communicate with
each other. This has created a very interoperable environment for the
users and they can choose and pick the device they like and still can
communicate. However, in the industrial world this has not happened yet
and currently there is very little interoperability. Vendors use
proprietary systems and they work within their ecosystems. So the IoT
needs very different kind of business models based on openness,
interoperability, etc.
Q. Could you share an exciting example of industrial automation solving problems faster in today’s world?
A. Recently the
Industrial Internet Consortium (IIC) announced their first test bed for
smart tools, where National Instruments is involved in along with Tech
Mahindra, Bosch and Cisco. Together we are creating a track and trace
test bed for smart tracking and inspection. Let me give you concrete use
case of a track and trace application that we have been involved in
with Airbus: A given subassembly of an airplane has roughly 400,000
points that need to be tightened down, which requires over 1,100 basic
tightening tools in the current production process. The operator has to
closely follow a list of steps and ensure the proper torque law settings
for each location using the correct tool. Because of the manual
process, human error adds a lot of risk to the production. This is
significant since even a single location being tightened down
incorrectly could cost hundreds of thousands of dollars in the long run.
A smart tightening tool understands which task the operator is about to
perform using vision to process its surroundings and automatically set
the torque. And the device can record the outcome of the task in a
central database to ensure the location was set properly. With the
central manufacturing execution system (MES) database and the
distributed intelligence of the devices, production managers can
precisely pinpoint the procedures and processes that need to be reviewed
during quality control and certification.
Q. What is the difference between implementing automation then and now?
A. One major change was
that in the past the principles that were applied on a factory floor
could be described as being strictly “master-slave” type. A lot of raw
data would be collected from different devices and centrally analysed
before an action was taken, whereas now we have more intelligent
processing in the devices before it is passed on. The big thing with IoT
will be in the services you can provide around monitoring and
maintenance, and predicting before a “thing” fails. So in general we
will see a big move from traditional factories to so-called smart
factories, which in Germany for instance are often referred to as
Industrie 4.0, the fourth industrial revolution.
Q. Could you share an interesting consumer application that you’ve seen using IoT?
A. One interesting
application would be a connected autonomous lawn mower. It would mow
your lawn automatically without human interaction. At the recent Bosch
Connected World conference, where we also announced the first IIC track
and trace testbed that I just mentioned, a version of a lawn mower was
presented with which the operator could communicate. For instance, the
operator would say “cut the grass,” and the machine would start the
work. That is a classic example of cyber-physical systems (CPS) in
action. These types of applications might be a luxury item for you and
me, but for someone who is physically challenged this would be a very
useful utility where the thing, which is just a small box, goes around,
cutting grass. That’s a very tangible example of CPS.
Q. How about an interesting IoT example from the industrial side?
A. The high-end cars of
today are great examples of CPS or the “Internet of Big Things”. They
have around 50 to 70 networked ECUs that can perform a lot of functions
automatically in the car, including parking. What they don’t necessarily
do today is to communicate with each other and be truly autonomously
functioning. But as mentioned earlier, 5G will be an enabler for this
type of applications. Speaking of cars, as you know, cars are a big deal
in Germany. You can configure a car on the web and they will build it
for you. Now the interesting thing is that in these three or four
months, while the car is being built for you, the manufacturer can
exactly tell you where and in which manufacturing stage your car is at
the moment. The manufacturing process is based on the vision of
Industrie 4.0, allowing a certain level of traceability. It’s honestly a
side effect because they originally did it so that they can plan the
logistics and the production management of the car by having it
connected to the ERP system. This is already happening and pretty soon
we will see this entering the next level.
Wireless Gesture-Controlled Robot
Wireless Gesture-Controlled Robot
(IoT)
In this project we are going to control a robot wirelessly using hand gestures. This is an easy, user-friendly way to interact with robotic systems and robots. An accelerometer is used to detect the tilting position of your hand, and a microcontroller gets different analogue values and generates command signals to control the robot. This concept can be implemented in a robotic arm used for welding or handling hazardous materials, such as in nuclear plants. The author’s prototype is shown in Fig. 1.
Circuit and working
The block diagram of the wireless gesture-controlled robot is shown in Fig. 2. The circuit diagram of the transmitter section of the wireless gesture-controlled robot is shown in Fig. 3 and of the receiver section in Fig. 4.ATmega328. ATmega328 is a single-chip microcontroller from Atmel and belongs to the mega AVR series. The Atmel 8-bit AVR RISC based microcontroller combines 32kB ISP flash memory with read-while-write capabilities, 1kB EEPROM, 2kB SRAM, 23 general-purpose I/O lines, 32 general-purpose working registers, three flexible timers/counters with compare modes, internal and external interrupts, serial programmable USART, a byte-oriented 2-wire serial interface, SPI serial port, 10-bit A/D converter, programmable watch-dog timer with an internal oscillator and five software-selectable power-saving modes.
The
device operates between 1.8 and 5.5 volts. It achieves throughputs
approaching one MIPS per MHz. An alternative to ATmega328 is ATmega328p.ADXL335.
This is a complete three-axis acceleration measurement system. ADXL335
has a minimum measurement range of ±3g. It contains a
poly-silicon-surface micro-machined sensor and signal-conditioning
circuitry to implement open-loop acceleration measurement architecture.
Output signals are analogue voltages that are proportional to
acceleration. The accelerometer can measure the static acceleration of
gravity in tilt-sensing applications as well as dynamic acceleration
resulting from motion, shock or vibration.The
sensor is a poly-silicon-surface micro-machined structure built on top
of a silicon wafer. Poly-silicon springs suspend the structure over the
surface of the wafer and provide resistance against acceleration forces.
Deflection of the structure is measured using a differential capacitor
that consists of independent fixed plates and plates attached to the
moving mass.
Fixed plates are driven by 180° out-of-phase square waves. Acceleration deflects the moving mass and unbalances the differential capacitor, resulting in a sensor output whose amplitude is proportional to acceleration. Phase-sensitive demodulation techniques are then used to determine the magnitude and direction of the acceleration.L293D. This is a 16-pin DIP package motor driver IC (IC6) having four input pins and four output pins. All four input pins are connected to output pins of the decoder IC (IC5) and the four output pins are connected to DC motors of the robot. Enable pins are used to enable input/output pins on both sides of IC6.
Encoder (HT12E) and decoder (HT12D) ICs.
The 212 encoders are a series of CMOS LSIs for remote-control system
applications. These are capable of encoding information that consists of
N address bits and 12 N data bits. Each address/data input can be set
to one of two logic states. Programmed addresses/data are transmitted
together with header bits via an RF or infra-red transmission medium
upon receipt of a trigger signal. The capability to select a TE trigger
on HT12E or a data (DIN) trigger on HT12D decoder further enhances the
application flexibility of 212 series of encoders. The HT12D also
provides a 38kHz carrier for infra-red systems.
Download the PCB and Component Layout PDFs: Click HereDownload the Source Code: Click here
Transmitter. The transmitter consists of ATmega328 microcontroller (IC2), ADXL335 accelerometer, HT12E encoder (IC4) and 433MHz RF transmitter module (TX1). In this circuit, two analogue outputs from ADXL335 pins (x, y) are connected with input pins (23, 24) of the microcontroller. Analogue signals are converted to digital signals through the microcontroller. Digital outputs from pins 16, 17, 18 and 19 of the microcontroller are directly sent to pins 13, 12, 11 and 10 of encoder IC4. This data is encoded and transmitted via RF module TX1.Receiver. The receiver part consists of 433MHz RF receiver module (RX1), HT12D decoder (IC5) and L293D motor driver (IC6) to run the motors. Here, receiver module RX1 receives the transmitted signal, which is decoded by decoder IC to get the same digital outputs. Four outputs of IC6 drive two motors. The robot moves as per tilt direction of the accelerometer in the transmitter. The direction of the robot movement is as per logic listed in Table I.Software program
The software program is written in Arduino programming language. We programmed a fresh ATmega328 microcontroller with the help of Arduino IDE 1.0.5 and an Arduino Uno board.
First, we have to load bootloader code into the microcontroller. For that, we used Arduino Uno for in-system programming (ISP) given in the IDE, by selecting File → Examples → Arduino ISP. Once the bootloader is uploaded into the microcontroller, gesture.ino code of this project can be uploaded.Construction and testing
An actual-size, single-side PCB layout of the transmitter circuit is shown in Fig. 5 and its component layout in Fig. 6. An actual-size, single-side PCB layout of the receiver circuit is shown in Fig. 7 and its component layout in Fig. 8.The transmitter section can be held in your palm or on the other side (refer Fig. 9). The receiver module is mounted on the robot.Mount all components on the PCBs shown here to minimise assembly errors. Fix the receiver PCB and 4.5V battery on the chassis of the robot. Fix two motors, along with wheels, at the rear side of the robot and a castor wheel on the front. After uploading the main code into the microcontroller, remove it from the Arduino Uno board and insert it into the populated transmitter PCB.Now, switch-on the power supplies in the transmitter as well as receiver circuits. Attach the transmitter circuit to your hand and move your hand forwards, backwards and sideways. Directions of the robot movement are given in Table I. The robot will stop if you keep your palm horizontal, parallel to the Earth’s surface.For troubleshooting, first verify that voltages at various test points are as per Table II.
In this project we are going to control a robot wirelessly using hand gestures. This is an easy, user-friendly way to interact with robotic systems and robots. An accelerometer is used to detect the tilting position of your hand, and a microcontroller gets different analogue values and generates command signals to control the robot. This concept can be implemented in a robotic arm used for welding or handling hazardous materials, such as in nuclear plants. The author’s prototype is shown in Fig. 1.
 Fig. 1: Author’s prototype |
 Fig. 2: Block diagram of the wireless gesture-controlled robot |
The block diagram of the wireless gesture-controlled robot is shown in Fig. 2. The circuit diagram of the transmitter section of the wireless gesture-controlled robot is shown in Fig. 3 and of the receiver section in Fig. 4.ATmega328. ATmega328 is a single-chip microcontroller from Atmel and belongs to the mega AVR series. The Atmel 8-bit AVR RISC based microcontroller combines 32kB ISP flash memory with read-while-write capabilities, 1kB EEPROM, 2kB SRAM, 23 general-purpose I/O lines, 32 general-purpose working registers, three flexible timers/counters with compare modes, internal and external interrupts, serial programmable USART, a byte-oriented 2-wire serial interface, SPI serial port, 10-bit A/D converter, programmable watch-dog timer with an internal oscillator and five software-selectable power-saving modes.
 Fig. 3: Transmitter section of the wireless gesture-controlled robot |
 Fig. 4: Receiver section of the wireless gesture-controlled robot |
 |
Fixed plates are driven by 180° out-of-phase square waves. Acceleration deflects the moving mass and unbalances the differential capacitor, resulting in a sensor output whose amplitude is proportional to acceleration. Phase-sensitive demodulation techniques are then used to determine the magnitude and direction of the acceleration.L293D. This is a 16-pin DIP package motor driver IC (IC6) having four input pins and four output pins. All four input pins are connected to output pins of the decoder IC (IC5) and the four output pins are connected to DC motors of the robot. Enable pins are used to enable input/output pins on both sides of IC6.
 |  |
 Fig. 5: An actual-size PCB layout of the transmitter circuit |  Fig. 7: An actual-size PCB layout of the receiver circuit |
 Fig. 6: Component layout of the transmitter circuit |  Fig. 8: Component layout of the receiver circuit |
Download the PCB and Component Layout PDFs: Click HereDownload the Source Code: Click here
Transmitter. The transmitter consists of ATmega328 microcontroller (IC2), ADXL335 accelerometer, HT12E encoder (IC4) and 433MHz RF transmitter module (TX1). In this circuit, two analogue outputs from ADXL335 pins (x, y) are connected with input pins (23, 24) of the microcontroller. Analogue signals are converted to digital signals through the microcontroller. Digital outputs from pins 16, 17, 18 and 19 of the microcontroller are directly sent to pins 13, 12, 11 and 10 of encoder IC4. This data is encoded and transmitted via RF module TX1.Receiver. The receiver part consists of 433MHz RF receiver module (RX1), HT12D decoder (IC5) and L293D motor driver (IC6) to run the motors. Here, receiver module RX1 receives the transmitted signal, which is decoded by decoder IC to get the same digital outputs. Four outputs of IC6 drive two motors. The robot moves as per tilt direction of the accelerometer in the transmitter. The direction of the robot movement is as per logic listed in Table I.Software program
The software program is written in Arduino programming language. We programmed a fresh ATmega328 microcontroller with the help of Arduino IDE 1.0.5 and an Arduino Uno board.
First, we have to load bootloader code into the microcontroller. For that, we used Arduino Uno for in-system programming (ISP) given in the IDE, by selecting File → Examples → Arduino ISP. Once the bootloader is uploaded into the microcontroller, gesture.ino code of this project can be uploaded.Construction and testing
 Fig. 9: Transmitter module mounted on the back of the palm |
An actual-size, single-side PCB layout of the transmitter circuit is shown in Fig. 5 and its component layout in Fig. 6. An actual-size, single-side PCB layout of the receiver circuit is shown in Fig. 7 and its component layout in Fig. 8.The transmitter section can be held in your palm or on the other side (refer Fig. 9). The receiver module is mounted on the robot.Mount all components on the PCBs shown here to minimise assembly errors. Fix the receiver PCB and 4.5V battery on the chassis of the robot. Fix two motors, along with wheels, at the rear side of the robot and a castor wheel on the front. After uploading the main code into the microcontroller, remove it from the Arduino Uno board and insert it into the populated transmitter PCB.Now, switch-on the power supplies in the transmitter as well as receiver circuits. Attach the transmitter circuit to your hand and move your hand forwards, backwards and sideways. Directions of the robot movement are given in Table I. The robot will stop if you keep your palm horizontal, parallel to the Earth’s surface.For troubleshooting, first verify that voltages at various test points are as per Table II.
Sunday, 15 November 2015
What are the side effects of mobile phones?
First published on: 1-4-2012
Cellphone Hazards And RecommendationsMobile phones have been found to cause changes in the brain activity, reaction times and sleep patterns. The length of cellphone call affects the intensity of these symptoms. As it’s not possible for us to stop using mobile phones altogether, precautionary measures are needed to avoid their ill effects
Mobile phones use electromagnetic radiation in the microwave range, which may be harmful to human health. They communicate by transmitting radio waves through a network of fixed antennae called base stations.Radio-frequency waves are electromagnetic fields, and unlike ionising radiation such as X-rays or gamma rays, cannot break chemical bonds nor cause ionisation in the human body. All radiations and fields of the electromagnetic spectrum that do not normally have sufficient energy to produce ionisation in matter are termed as non-ionising radiation. These are characterised by energy per photon of less than about 12 electron volts (eV), wavelengths greater than 100 nanometres (nm) and frequencies lower than 3×1015 Hz.
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In response to public and governmental concern, the World Health Organisation (WHO) started the International Electromagnetic Fields (EMF) Project in 1996 to assess the scientific evidence of possible adverse health effects of electromagnetic fields. Given the immense number of people who use mobile phones, even a small increase in the incidence of adverse effects on health could have major public health implications. Because exposure to the RF fields emitted by mobile phones is generally more than a thousand times than from base stations, there is a greater likelihood of any adverse effect of handsets.Health hazards
A large number of studies have been performed over the last two decades to assess whether mobile phones pose a potential health risk. An assessment was published in 2007 by the European Commission Scientific Committee on Emerging and Newly Identified Health Risks (SCENIHR). The research clearly showed an increased risk of traffic accidents when mobile phones (either handheld or with a hands-free kit) are used while driving.Electromagnetic interference is also a major concern. When mobile phones are used close to some medical devices (including pacemakers, implantable defibrillators and certain hearing aids), there is the possibility of interference with their operation.
Other health effects of using mobile phones include changes in the brain activity, reaction times and sleep patterns.Radiation absorption. Part of the radio waves emitted by a cellphone is absorbed by the human head. The rate at which the radiation is absorbed by the human body is measured by the specific absorption rate (SAR), and its maximum levels for latest handsets have been set by governmental regulating agencies in many countries.SAR is defined as the time derivative of the incremental energy absorbed by or dissipated in an incremental mass contained in a volume element of a given density. SAR values are heavily dependent on the size of the averaging volume.In the USA, the Federal Communications Commission (FCC) has set an SAR limit of 1.6W/kg, averaged over a volume of one gram of tissue, for the head. In Europe, the limit is 2W/kg, averaged over a volume of 10 grams of tissue.Measurement of SAR value is a complicated process and comprises a phantom human head, specially developed liquids, a robot fitted with a measurement probe and a mobile phone powered up to its maximum certified power level.
Thermal effects. Tissue heating is the principal mechanism of interaction between radio-frequency energy and the human body. Tissue is a dielectric material which is heated by rotations of polar molecules induced by the microwave radiation.At the frequencies used by mobile phones, most of the energy is absorbed by the skin and other superficial tissues, resulting in negligible temperature rise in the brain or any other organs of the body. In the case of a person using a cellphone, most of the heating effect occurs at the surface of the head, causing its temperature to increase by a fraction of a degree. The local blood flow mechanism of the brain is capable of disposing of excess heat. However, the cornea of eye does not have temperature regulation mechanism and is more prone to produce cataracts.Long-duration cellphone usage also causes burning effects to the ear and ear-aches, or sharp pains inside the ear to the same side of the head as the phone is held. Some users even experience pain descending down from just behind the ear onto the jaw. Some users feel numbing sensations or tingling mainly in the outer area of ear, face or jaw.Eye problems may include fluttering of the eyelids, blurring of vision and bloodshot eye—always in the eye nearest the cellphone. Several studies have indicated that low-level RF exposure due to cellphones could cause significant visual effects, including the destruction of corneal endothelial cells, increased vascular permeability and destruction of photoreceptors in the retina.
Non-thermal effects. Some biophysicists argue that there are several thermoreceptor molecules in cells, which activate a cascade of second and third messenger systems, gene expression mechanisms and production of heat-shock proteins in order to defend the cells against metabolic cell stress caused by heat. The increases in temperature that cause these changes are too small to be detected.Some studies indicated that stress proteins are unrelated to thermal effects. These studies proved that stress proteins occur for extremely low frequencies (ELF) and radio frequencies which have very different energy levels. Some studies indicated a leakage of albumin into the brain via a permeated blood-brain barrier. Several other studies indicated that the blood-brain barrier breaks down with exposure to low-intensity cellphone frequency.Cognitive effects. The impact of cellphone radiation on cognitive functions of humans has been studied by several researchers. These studies confirmed slower response to a spatial working memory task when exposed to cellphone radiation.The Defence Evaluation and Research Agency (DERA), the UK’s largest science and technology organisation, has conducted research on cellphones’ EM radiation on the brain cells of rats and showed loss of memory for short periods. Several users of mobile phones also reported short-term memory loss. The cognitive functions are heavily affected by longer exposure.
EM allergic reaction. A number of studies have investigated the effects of mobile phone radiation specifically during and after its use. The users reported several unspecific symptoms like burning and tingling sensations in the skin of the head and extremities, sleep disturbances, dizziness, fatigue, loss of mental attention, reaction times and memory retentiveness, headaches, heart palpitations, blood pressure and disturbances in digestive system.Most users reported pain or ache on the same side as they held the phone and normally in the temporal region. When pain is located on one side of the head, users can invariably reproduce it on the other side by switching ears in an effort to obtain temporary relief.Genotoxic effects. Cellphone RF radiation at both 900 MHz and 1800 MHz and SAR of 0.4-27.5W/kg showed a correlation between increasing SAR and decreased motility and vitality in sperm, increased oxidative stress, stimulating DNA base adduct formation and increased DNA fragmentation. A European study named REFLEX (Risk Evaluation of Potential Environmental Hazards from Low Energy Electromagnetic Field Exposure Using Sensitive in-vitro Methods) indicated some evidence of DNA damage of cells in in-vitro cultures, damage to chromosomes, boosted rate of cell division and alterations in the activity of certain genes.
Cancer. A multinational case-control study on adults, INTERPHONE, coordinated by the International Agency for Research on Cancer (IARC), investigated whether the RF fields emitted by cellphones increased the risk of cancer. The study focused on tumours arising in the tissues most exposed to RF fields from mobile phones: glioma and meningioma (the most common types of brain tumours), acoustic neurinoma and parotid gland tumours. It found no increased risk of glioma or meningioma but there were some indications of an increased risk of glioma for those who reported the highest 10 per cent of cumulative hours of cellphone use.However, it has been suggested that EM fields associated with cellphones may play a role in speeding up the development of an existing cancer. Some studies reported lump in the neck or ear (lymphomas) also.
Recommendations
To date, research does not suggest any consistent evidence of adverse health effects from exposure to EM fields at levels below those that cause tissue heating. The WHO has issued a precautionary principle applied in circumstances with a high degree of scientific uncertainty, reflecting the need to take action for a potentially serious risk without awaiting the results of scientific research. Some recommendations to minimise the possible health hazards are:
1. Keep the cellphone as far away from your body as possible. By moving the cellphone just 5 cm away from your head while talking on it, electromagnetic radiation that reaches to head is reduced by 75 per cent.
2. Turn your cellphone off at night because EM radiation emitted by the cellphone can disturb sleep quality.
 Electromagnetic field penetration in an adult and a child |
3. Avoid carrying your cellphone in your pocket, on your belt or in your hand. If you do carry the cellphone in your pocket or hand bag, always position it such that the keypad faces towards you. This way the antenna faces away from you. Body tissue in the abdomen absorbs radiation more quickly than the head. The hip produces 80 per cent of the body’s red blood cells and is especially vulnerable to electromagnetic radiation damage. Close proximity may also damage fertility.
4. Consider using your laptop computer to make calls or send an instant message.
5. Avoid using wired headsets. Headsets including the ear buds that come with most cellphones today, act as an antenna, channeling electromagnetic radiation directly to the ear canal. When you use regular ear buds or ear pieces, you get three times more EM radiation than if you held the cellphone against your ear. Also, you get it directly into your ear canal, and ultimately to your brain. So it is recommended not to listen to music on a cellphone using headsets.
6. Use air-tube headsets with ferrite beads. Air-tube headsets are believed to be safer because these don’t work as antenna and EM radiation can’t travel up the air tube like it does on a regular wired earphone. Further, ferrite beads suppress EM radiation and dissipate it as heat. So, it is recommended to use airtube headsets with a ferrite bead placed as close as possible to the cellphone.
7. Use the speaker phone as much as possible. EM radiation decreases in direct proportion to the distance of the source from your body. So never hold the phone directly against your head.
8. Avoid making calls when travelling fast. Cellphones automatically increase output power when moving fast as these attempt to connect or handover to the next cellphone base station.9. When purchasing a cellphone, get one with low SAR.10. Avoid using a cellphone in metal enclosures like lifts, elevators, vehicles, subways and airplanes. Metal enclosures act like Faraday cage, trapping some of the radiation and reflecting it back upon you and others. So turn off your cellphone inside all metal enclosures.
11. Make calls when and where you have a strong signal. In most systems, the cellphone and the base station check the reception quality and signal strength, and increase or decrease the power level automatically, within a certain span, to accommodate for different situations such as inside or outside buildings and vehicles. When the signal is weak, cellphones automatically increase the power output, exposing you to greater EM radiation.
12. Limit the amount of time you talk on cellphones. Just a two-minute call on a cellphone may disturb the electrical activity of the brain for up to an hour. The more time you spend on mobile phone, the greater your risk of developing brain cancer. So keep your talking brief. You may be saving not only money but a life—quite possibly your own.
13. Use hands-free kit to decrease the radiation to the head.14. Do not use telephone in a car without an external antenna.
15. The base of a cordless phone emits high levels of EM radiation, even when it is not being used. So use a regular phone as much as possible. Regular phones are the safest bet for conversation and work.
16. Avoid using a cellphone when you are pregnant. The developing organs of the fetus are most sensitive to any possible EM radiation exposure. Moreover, cellphones generate low levels of non-ionising radiation, which are more likely to cause behavioural issues in children after birth. High amounts of these waves can disrupt body tissues—that’s one reason why it is suggested to wear protective shielding when getting an X-ray done.
17. Don’t allow children to use a cellphone, except for emergencies. Children are at a greater risk because their skulls have not completely thickened. Children’s skulls are thinner and their brain contains more fluid than adults’. Exposure of young children to cellphone radiation may be more detrimental to their health, especially during the development and maturation of the central nervous system, immune system and critical organs. Electromagnetic fields easily penetrate through the brain of children, increasing the risk of cancer (see the figure). The electromagnetic field penetration in an adult and a child clarifies it.
18. Use a Bluetooth headset in order to minimise EM radiation. It has been found that Bluetooth headsets emit 1/100th the EM radiation of a normal cellphone. But whatever is radiated by this type of headset directly enters the ear canal and ultimately disturbs the electrical activity of the brain.
19. Use a cellphone radiation protection device which has a patented shield technology that superimposes a low-frequency noise-field onto the radio frequency to make it harmless to the body.
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