seminar report omega

7/31/2019 Seminar Report Omega

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APRACTICAL TRAININGSEMINAR REPORTON

OMEGA ELECTRONICS, JAIPUR

SESSION 2012-2013Submitted for the partial fulfillment for the award of the degree ofBACHELOR OF TECHNOLOGYOFRAJASTHAN TECHNICAL UNIVERSITY, KOTA

SUBMITTED BY:YATIN GUPTA08EEAEC0967th SEM (ECE)

---------------------------------------------------------------------------------------------------------------Department of Electronics & Communication EngineeringGOVT. ENGINEERING COLLEGE AJMER

(An Autonomous Institute of Govt. of Rajasthan)Badliya Chouraha, N.H. 8, By-Pass, Ajmer-305002

Website:www.ecajmer.ac.inPh no. 0145-2671773, 776,800,801

PREFACE

With growing developments in the field of mechtronics , mathematical

modeling robotics has come long way from an iron piece that moves a fewinches to machines capable of jumping from high buildings detectingmines,performing various operations and troubleshooting various operations.Robotics means the study and application of robot technology. The goal ofrobotics is to mimic natural world as closely as possible. The main elementsin the robot are the moving elements and the sensors.
http://www.ecajmer.ac.in/http://www.ecajmer.ac.in/http://www.ecajmer.ac.in/http://www.ecajmer.ac.in/


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This paper deals with the evolution of robots, the elements of robotics, thelimitation of robots, and the various applications of robots. In theapplication part this paper expects to cover in detail robot surgery androbonauts (the robots used in space), .It also deals with the introduction

to interfacing.

ACKNOWLEDGEMENT

I sincerely thank my seminar coordinator Mrs. Rekha Mehra (AssociateProfessor, E.C.E.) Govt. Engineering College, Ajmer, who went out of waytoprovide me every possible facility and support me in presenting seminarsmoothly and successfully. It was her able guidance and support, which

resulted in the successful presentation of my seminar within the specifiedtime. Their unflinching help and encouragement was a constant course ofinspiration to me.

I would also like to express my deep sense of gratitude to the ManagingDirector Omega Electronics and all its employees for extending their helpand painstakingly helping us throughout our training period. I would alsolike to thank all the members of the training and placement cell for helpingus.

A seminar owes its success from commencement to completion, to peopleinvolved with seminar at various stages. I avail this opportunity to conveymy sincere thanks to all individuals who have helped and assisted me incarrying and bringing out this seminar.

Last, but not the least, the co-operation and help received from teachersand friends is gratefully acknowledged.

YATIN GUPTA 08EEAEC0967th SEM (ECE)

CONTENTS

1. Brief history of Omega Electronics 5


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2. Introduction to basic electronics ...........62.1 Diodes.6 2.2 Transistor.82.3 Field effect transistor......9

3. Soldering.114. Switches .145. Introduction to Robotics 176. Anatomy of robot...207. Gear system..258. Sensors 289. Control System .....3110. Actuators .......3211. Power Supply.33

12. Physical Interfacing Devices.3513. Conclusion.3914. Bibliography..40

1. BRIEF HISTORY OF OMEGA

Mr. Y. P. Agarwal, an eminent & qualified Electronic professional, foundedOMEGA ELECTRONICS in the year 1962. Heading the company as ChiefExecutive,

he is continuing his expert guidance and OMEGA is achieving new horizonsofsuccess under his supervision. Attributing to his foresight, OMEGA iscurrently one of the organizations in the country, which enjoys an all Indiapatronage and coverage. An ISO certified Company 9001:2000, situated inMalviya Nagar RICO Industrial Area, Jaipur, (Rajasthan)

Omega manufactures electronic educational training equipments andinstruments to assist educators in various technical fields such as

telecommunications, microprocessors, power electronics, processinstrumentation.Omega Teaching Aids & Equipments bring technical theory to life, teachingthe latest technology and helping trainees to develop valuable troubleshooting skills.

2. INTRODUCTION TO BASIC ELECTRONICS


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In basic electronics we had a review on concepts of various basic electronicdevices like diodes, transistors. FETs, their construction, V-Icharacteristics, working, kit display and application in electronics.

DIODESIn electronics, a diode is a two-terminal electronic component. Asemiconductor diode, the most common type today, is a crystalline piece ofsemiconductor material connected to two electrical terminals. A vacuumtubediode (now little used except in some high-power technologies) is avacuumtube with two electrodes: a plate and a cathode.The most common function of a diode is to allow an electric current to pass

in one direction (called the diode's forward direction), while blockingcurrent in the opposite direction (the reverse direction). Thus, the diodecan be thought of as an electronic version of a check valve. Thisunidirectional behavior is called rectification, and is used to convertalternating current to direct current, and to extract modulation from radiosignals in radio receives.However, diodes can have more complicated behavior than this simple on-offaction. Semiconductor diodes do not begin conducting electricity until a

certain threshold voltage is present in the forward direction (a state inwhich the diode is said to be forward biased). The voltage drop across aforward biased diode varies only a little with the current, and is afunction of temperature; this effect can be used as a temperature sensororvoltage reference.Semiconductor diodes have non-linear electrical characteristics, which canbe tailored by varying the construction of their P-N junction. These areexploited in special purpose diodes that perform many different functions.

For example, diodes are used to regulate voltage (Zenger diodes), toprotectcircuits from high voltage surges (Avalanche diodes), to electronically tuneradio and TV receivers (varactor diodes), to generate radio frequencyoscillations (tunnel diodes, Gunn diodes, IMPATT diodes), and to producelight (light emitting diodes). Tunnel diodes exhibit negative resistance,which makes them useful in some types of circuits.


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Diodes were the first semiconductor electronic devices. The discovery ofcrystals' rectifying abilities was made by German physicist Ferdinand Braunin 1874. The first semiconductor diodes, called cat's whisker diodes,developed around 1906, were made of mineral crystals such as galena.

Todaymost diodes are made of silicon, but other semiconductors such asgermaniumare sometimes used.Currentvoltage characteristic:-A semiconductor diodes behavior in a circuit is given by itscurrentvoltage characteristic, or IV graph (see graph below). The shapeofthe curve is determined by the transport of charge carriers through the

so-called depletion layer or depletion region that exists at the p-njunction between differing semiconductors. When a p-n junction is firstcreated, conduction band (mobile) electrons from the N-doped regiondiffuseinto the P-doped region where there is a large population of holes (vacantplaces for electrons) with which the electrons recombine. When a mobileelectron recombines with a hole, both hole and electron vanish, leavingbehind an immobile positively charged donor (dopant) on the N-side andnegatively charged acceptor (dopant) on the P-side. The region around the

p-n junction becomes depleted of charge carriers and thus behaves as aninsulator.

Fig 1: V-I characteristic of diodeHowever, the width of the depletion region (called the depletion width)cannot grow without limit. For each electron-hole pair that recombines, apositively charged dopant ion is left behind in the N-doped region, and anegatively charged dopant ion is left behind in the P-doped region. As

recombination proceeds more ions are created, an increasing electric fielddevelops through the depletion zone which acts to slow and then finallystoprecombination. At this point, there is a built-in potential across thedepletion zone.If an external voltage is placed across the diode with the same polarity asthe built-in potential, the depletion zone continues to act as an insulator,


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preventing any significant electric current flow (unless electron/hole pairsare actively being created in the junction by, for instance, light. seephotodiode). This is the reverse bias phenomenon. However, if the polarityof the external voltage opposes the built-in potential, recombination can

once again proceed, resulting in substantial electric current through thep-n junction (i.e. substantial numbers of electrons and holes recombine atthe junction). For silicon diodes, the built-in potential is approximately0.7 V (0.3 V for Germanium and 0.2 V for Schottky). Thus, if an externalcurrent is passed through the diode, about 0.7 V will be developed acrossthe diode such that the P-doped region is positive with respect to theN-doped region and the diode is said to be turned on as it has a forwardbiasNormal (p-n) diodes, which operate as described above, are usually made

ofdoped silicon or, more rarely, germanium. Before the development ofmodernsilicon power rectifier diodes, cuprous oxide and later selenium was used;its low efficiency gave it a much higher forward voltage drop (typically 1.4to 1.7 V per cell, with multiple cells stacked to increase the peakinverse voltage rating in high voltage rectifiers), and required a largeheat sink (often an extension of the diodes metal substrate), much largerthan a silicon diode of the same current ratings would require. The vast

majority of all diodes are the p-n diodes found in CMOS integrated circuits,which include two diodes per pin and many other internal diodes.TRANSISTORA transistor is a semiconductor device used to amplify and switch electronicsignals. It is composed of a semiconductor material with at least threeterminals for connection to an external circuit. A voltage or currentapplied to one pair of the transistor's terminals changes the currentflowing through another pair of terminals. Because the controlled (output)power can be much more than the controlling (input) power, a transistor

canamplify a signal. Today, some transistors are packaged individually, butmany more are found embedded in integrated circuits.The transistor is the fundamental building block of modern electronicdevices, and is ubiquitous in modern electronic systems. Following itsrelease in the early 1950s the transistor revolutionized the field ofelectronics, and paved the way for smaller and cheaper radios, calculators,


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and computers, among other thing.

The transistor is the key active component in practically all modernelectronics. Many consider it to be one of the greatest inventions of the

20th century. Its importance in today's society rests on its ability to bemass produced using a highly automated process (semiconductor devicefabrication) that achieves astonishingly low per-transistor costs.Although several companies each produce over a billion individuallypackaged(known as discrete) transistors every year, the vast majority of transistorsnow are produced in integrated circuits (often shortened to IC, microchipsor simply chips), along with diodes, resistors, capacitors and otherelectronic components, to produce complete electronic circuits. A logic gate

consists of up to about twenty transistors whereas an advancedmicroprocessor, as of 2011, can use as many as 3 billion transistors(MOSFETs). About 60 million transistors were built this year [2002] ... for[each] man, woman, and child on Earth."

Fig.2: (a) Symbol of transistor. (b) Different types of transistors

The transistor's low cost, flexibility, and reliability have made it a

ubiquitous device. Transistorized mechatronic circuits have replacedelectromechanical devices in controlling appliances and machinery. It isoften easier and cheaper to use a standard microcontroller and write acomputer program to carry out a control function than to design anequivalent mechanical control function.

FIELD EFFECT TRANSISTORThe field-effect transistor (FET) is a transistor that relies on an electricfield to control the shape and hence the conductivity of a channel of one

type of charge carrier in a semiconductor material. FETs are sometimescalled uni polar transistors to contrast their single-carrier-type operationwith the dual-carrier-type operation of bipolar (junction) transistors(BJT). The concept of the FET predates the BJT, though it was notphysicallyimplemented until after BJTs due to the limitations of semiconductormaterials and the relative ease of manufacturing BJTs compared to FETs at


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the time

Fig.3: Field effect transistor

FET operation:-The FET controls the flow of electrons (or electron holes) from the sourceto drain by affecting the size and shape of a "conductive channel" createdand influenced by voltage (or lack of voltage) applied across the gate andsource terminals (For ease of discussion, this assumes body and source areconnected). This conductive channel is the "stream" through whichelectronsflow from source to drain.

In an n-channel depletion-mode device, a negative gate-to-source voltagecauses a depletion region to expand in width and encroach on the channelfrom the sides, narrowing the channel. If the depletion region expands tocompletely close the channel, the resistance of the channel from source todrain becomes large, and the FET is effectively turned off like a switch.Likewise a positive gate-to-source voltage increases the channel size andallows electrons to flow easily.Conversely, in an n-channel enhancement-mode device, a positivegate-to-source voltage is necessary to create a conductive channel, since

one does not exist naturally within the transistor. The positive voltageattracts free-floating electrons within the body towards the gate, forming aconductive channel. But first, enough electrons must be attracted near thegate to counter the dopant ions added to the body of the FET; this forms aregion free of mobile carriers called a depletion region, and thephenomenonis referred to as the threshold voltage of the FET. Further gate-to-sourcevoltage increase will attract even more electrons towards the gate whichare

able to create a conductive channel from source to drain; this process iscalled inversion.

3. SOLDERINGSoldering is a process in which two or more metal items are joinedtogetherby melting and flowing a filler metal into the joint, the filler metal


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having a lower melting point than the work piece. Soldering differs fromwelding in that the work pieces are not melted. There are three forms ofsoldering, each requiring higher temperatures and each producing anincreasingly stronger joint strength: soft soldering, which originally used

a tin-lead alloy as the filler metal, silver soldering, which uses an alloycontaining silver, and brazing which uses a brass alloy for the filler. Thealloy of the filler metal for each type of soldering can be adjusted tomodify the melting temperature of the filler. Soldering appears to be a hotglue process, but it differs from gluing significantly in that the fillermetals alloy with the work piece at the junction to form a gas- andliquid-tight bond.

Fig.4 (a):-good joint (b):-bad joint

Soft soldering is characterized by having a melting point of the fillermetal below approximately 400 C (752 F), whereas silver soldering andbrazing use higher temperatures, typically requiring a flame or carbon arctorch to achieve the melting of the filler. Soft solder filler metals aretypically alloys (often containing lead) that have liquids temperaturesbelow 350C.In the soldering process, heat is applied to the parts to bejoined, causing the solder to melt and to bond to the work pieces in analloying process called wetting. In stranded wire, the solder is drawn up

into the wire by capillary action in a process called wicking. Capillaryaction also takes place when the work pieces are very close together ortouching. The joint strength is dependent on the filler metal used, wheresoft solder is the weakest and the brass alloy used for brazing is thestrongest. Soldering, which uses metal to join metal in a molecular bondhaselectrical conductivity and is water- and gas-tight. There is evidence thatsoldering was employed up to 5000 years ago in MesopotamiaApplications of soldering:-

Soldering was historically used to make jewelry items, cooking ware andtools. Currently, the two most common uses of soldering are in plumbingandin electronics where it is used to connect electrical wiring and to connectelectronic components to printed circuit boards (PCBs). It providesreasonably permanent but reversible connections between copper pipes inplumbing systems as well as joints in sheet metal objects such as food


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cans,roof flashing, rain gutters, and automobile radiators. Jewelry components,machine tools and some refrigeration and plumbing components are oftenassembled and repaired by the higher temperature silver soldering process.

Small mechanical parts are often soldered or brazed as well. Soldering isalso used to join lead came and copper foil in stained glass work. It canalso be used as a semi-permanent patch for a leak in a container orcookingvessel.Types of soldering:-1. Soft soldering.2. Silver soldering3. Blazing soldering

Required Items for soldering:- Soldering iron Filler metal Flux

Solders:-Soldering filler materials are available in many different alloys fordiffering applications. In electronics assembly, the eutectic alloy of 63%

tin and 37% lead (or 60/40, which is almost identical in performance to theeutectic) has been the alloy of choice. Other alloys are used for plumbing,mechanical assembly, and other applications.

Fig.5 (a): Solder iron (b.): Filler metal used in solderingCommon solder alloys are mixtures of tin and lead, respectively: 63/37: melts at 183 C (361 F) (eutectic: the only mixture that melts ata point, instead of over a range) 60/40: melts between 183190 C (361374 F)

50/50: melts between 185215 C (365419 F)

Flux:-The purpose of flux is to facilitate the soldering process. The obstacle toa successful solder joint is an impurity at the site of the union, e.g.dirt, oils or oxidation. The impurities can be removed by mechanicalcleaning or by chemical means, but the elevated temperatures required to


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melt the filler metal (the solder) encourages the work piece (and thesolder) to re-oxidize. This effect is accelerated as the solderingtemperatures increase and can completely prevent the solder from joiningto

the work piece. One of the earliest forms of flux was charcoal, which actsas a reducing agent and helps prevent oxidation during the solderingprocess. Some fluxes go beyond the simple prevention of oxidation andalsoprovide some form of chemical cleaning (corrosion).For many years, the most common type of flux used in electronics (softsoldering) was rosin-based, using the rosin from selected pine trees. It wasideal in that it was non-corrosive and non-conductive at normaltemperatures

but became mildly reactive (corrosive) at the elevated solderingtemperatures. Plumbing and automotive applications, among others,typicallyuse an acid-based (muriatic acid) flux which provides

cleaning of the joint. These fluxes cannot be used in electronics becausethey are conductive and because they will eventually dissolve the smalldiameter wires. Many fluxes also act as a wetting agent in the solderingprocess, reducing the surface tension of the molten solder and causing it to

flow and wet the work pieces more easily."Hard soldering" or "silver soldering" (performed with high-temperaturesolder containing up to 40% silver) is also often considered a form ofbrazing, since it involves filler materials with melting points in thevicinity of, or in excess of, 450 C. Although the term "silver soldering"is used much more often than "silver brazing", it may be technicallyincorrect depending on the exact melting point of the filler in use. Insilver soldering ("hard soldering"), the goal is generally to give abeautiful, structurally sound joint, especially in the field of jewelry.

Thus, the temperatures involved, and the usual use of a torch rather thananiron, would seem to indicate that the process should be referred to as"brazing" rather than "soldering", but the endurance of the "soldering"appellation serves to indicate the arbitrary nature of the distinction (andthe level of confusion) between the two processes.Induction soldering is a process which is similar to brazing. The source of


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heat in induction soldering is induction heating by high-frequency ACcurrent in a surrounding copper coil. This induces currents in the partbeing soldered, heat then being generated by resistive heating. The copperrings can be made to fit the part needed to be soldered for precision in the

work piece. Induction soldering is a process in which a filler metal(solder) is placed between the facing surfaces of (to be joined) metals. Thefiller metal in this process is melted at a fairly low temperature. Fluxesare commonly used in induction soldering. This is a process which isparticularly suitable for soldering continuously. The process is usuallydone with coils that wrap around a cylinder/pipe that needs to be soldered.Some metals are easier to solder than others. Copper, silver, and gold areeasy. Iron, mild steel and nickel are found to be more difficult. Because oftheir thin, strong oxide films, stainless steel and aluminum are even more

difficult. Titanium, magnesium, cast iron, some high-carbon steels,ceramics, and graphite can be soldered but it involves a process similar tojoining carbides. They are first plated with a suitable metallic elementthat induces interfacial bonding4. SWITCHESIn electronics, a switch is an electrical component that can break anelectrical circuit, interrupting the current or diverting it from oneconductor to another.The most familiar form of switch is a manually operated electromechanical

device with one or more sets of electrical contacts. Each set of contactscan be in one of two states: either 'closed' meaning the contacts aretouching and electricity can flow between them, or 'open', meaning thecontacts are separated and the switch is nonconducting. The mechanismactuating the transition between these two states (open or closed) can beeither a "toggle" (flip switch for continuous "on" or "off") or "momentary"(push-for "on" or push-for "off") type.

In electronics engineering, an ideal switch describes a switch that:

has no current limit during its ON state has infinite resistance during its OFF state has no voltage drop across the switch during its ON state has no voltage limit during its OFF state has zero rise time and fall time during state changes switches only once without "bouncing" between on and off positionsA switch may be directly manipulated by a human as a control signal to a


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system, such as a computer keyboard button, or to control power flow in acircuit, such as a light switch. Automatically operated switches can be usedto control the motions of machines, for example, to indicate that a garagedoor has reached its full open position or that a machine tool is in a

position to accept another work piece. Switches may be operated byprocessvariables such as pressure, temperature, flow, current, voltage, and force,acting as sensors in a process and used to automatically control a system.For example, a thermostat is a temperature-operated switch used tocontrol aheating process. A switch that is operated by another electrical circuit iscalled a relay. Large switches may be remotely operated by a motor drivemechanism. Some switches are used to isolate electric power from a

system,providing a visible point of isolation that can be pad-locked if necessaryto prevent accidental operation of a machine during maintenance, or toprevent electric shock.Types of switches:1. SPST (Single Pole Single Through)2. SPDT (Single Pole Double Through)3. DPST (Double Pole Single Through)4. DPDT (Double Pole Double Through)

Standard Switches

Type of Switch Circuit Symbol ExampleON-OFFSingle Pole, Single Throw = SPSTA simple on-off switch. This type can be used to switch the power supplytoa circuit.When used with mains electricity this type of switch must be in the live

wire, but it is better to use a DPST switch to isolate both live andneutral.SPST toggle switch(ON)-OFFPush-to-make = SPST MomentaryA push-to-make switch returns to its normally open (off) position when yourelease the button, this is shown by the brackets around ON. This is the


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standard doorbell switch.Push-to-make switchON-(OFF)Push-to-break = SPST Momentary

A push-to-break switch returns to its normally closed (on) position whenyourelease the button.Push-to-break switchON-ONSingle Pole, Double Throw = SPDTThis switch can be on in both positions, switching on a separate device ineach case. It is often called a changeover switch. For example, a SPDTswitch can be used to switch on a red lamp in one position and a green

lampin the other position.A SPDT toggle switch may be used as a simple on-off switch by connectingtoCOM and one of the A or B terminals shown in the diagram. A and B areinterchangeable so switches are usually not labelled.

ON-OFF-ONSPDT Centre Off

A special version of the standard SPDT switch. It has a third switchingposition in the centre which is off. Momentary (ON)-OFF-(ON) versions arealso available where the switch returns to the central off position whenreleased.SPDT toggle switch

SPDT slide switch(PCB mounting)

SPDT rocker switchDual ON-OFFDouble Pole, Single Throw = DPSTA pair of on-off switches which operate together (shown by the dotted linein the circuit symbol).A DPST switch is often used to switch mains electricity because it canisolate both the live and neutral connections.


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DPST rocker switchDual ON-ONDouble Pole, Double Throw = DPDTA pair of on-on switches which operate together (shown by the dotted line

inthe circuit symbol).A DPDT switch can be wired up as a reversing switch for a motor as showninthe diagram.ON-OFF-ONDPDT Centre OffA special version of the standard SPDT switch. It has a third switchingposition in the centre which is off. This can be very useful for motor

control because you have forward, off and reverse positions. Momentary(ON)-OFF-(ON) versions are also available where the switch returns to thecentral off position when released.DPDT slide switch

Wiring for Reversing Switc

5. INTRODUCTION TO ROBOTICS

Robotics is that branch which involves with the study and applications ofRobots. The goal of Robotics is to mimic natural world as closely aspossible. Robotics is a relatively new field of engineering (aboutapproximately 50 years old) and is finding many applications in differentareas.With growing developments in the field of mechtronics and mathematicmodeling, Robotics has come a long way. From an iron piece that couldmove

only a few inches, there are now machines capable of jumping from highrisebuildings, detecting landmines, performing complicated operations, andtroubleshooting. The word robot was introduced to the public by the Czechwriter Karel apek in his play R.U.R. (Rossum's Universal Robots),publishedin 1920.


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The word robotics is used to collectively define a field in engineering thatcovers the mimicking of various human characteristicsSound concepts inmanyengineering disciplines is needed for working in this particular field.

There are various definitions for the term Robot. Some of them areForce through intelligence.1. An automatic device that performs functions normally ascribed tohumansor a machine in the form of a human.2. A robot is a reprogrammable multifunctional manipulator designed tomovematerial, Parts, tools or specialized devices through variable programmedmotions for the Performance of a variety of tasks.

Robotics compared to other branches is a relatively new field ofengineering. It is a multi disciplinary field. The various branches involvedin the development of Robotics are:

Mechanical Engineering: Deals with the mechanisms of Robots and theirstructure.Electrical Engineering: Deals with the sensing and controlling of Robots.Computer Engineering: Deals with the motion planning and perception of

Robots.Though the branch of Robotics is new, the development of Robots startedinthe year 1250 when the first Robot was developed. In the period from1250 to1950 the Robots were developed for fun rather than for applicationsModel Based Robots: These Robots use exact models for the work they areentitled to do. They are not provided with any sensors. Hence, they are notrequired to act on external stimuli.

E.g.: A Robot which used for lifting heavy loads are model based as therewill always be a maximum load specified and the robot need not sense theload also there is no other course of action.Sensor Based Robots: These Robots are provided with sensors that have tochange the course of action based on the stimuli it receives. These Robotsare generally used for lower level works.E.g.: A Robot, which is used for maintenance of a furnace depending upon


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itstemperature. In the above case, there are various courses of action for theRobot and the Robot has to choose a course of action depending upon theinput stimuli received.

The present scenario of Robotics is unimaginable from just some stipulatedmotions to performing various complex operations and space visits, Robotshave found their application in all fields.Advantages of Robots:1. Robotics and automation can, in many situation, increase productivity,safety, efficiency, quality.2. Robots can work in hazardous environments3. Robots need no environmental comfort4. Robots work continuously without any humanity needs and illnesses

5. Robots have repeatable precision at all times6. Robots can be much more accurate than humans; they may have mili ormicroinch accuracy.7. Robots and their sensors can have capabilities beyond that of humans8. Robots can process multiple stimuli or tasks simultaneously, humans canonly one.9. Robots replace human workers who can create economic problemsDisadvantages of Robots:

1. Robots lack capability to respond in emergencies, this can cause2. Inappropriate and wrong responses3. A lack of decision-making power4. A loss of power5. Damage to the robot and other devices6. Human injuries7. Robots may have limited capabilities in8. Degrees of Freedom9. Dexterity

10. Sensors11. Vision systems12. Real-time Response13. Robots are costly, due to Initial cost of equipment15. Installation Costs16. Need for peripherals17. Need for training


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18. Need for Programming

6. ANATOMY OF ROBOT

The basic components of a robot system are :1. The locomotion system (Mechanical link)2. Actuators and transmissions3. Sensors4. Controllers5. User interface6. Power conversion unit

LOCOMOTION SYSTEM:

As the name suggests a mobile robot must have a system to make it move.Thissystem gives our machine the ability to move forward, backward and taketurns. It may also provide for climbing up and down.The concept of locomotion invariably needs rotational motion e.g. a wheeldriven by some power source. This involves conversion of electrical energyinto mechanical energy, which we can easily achieve using electricalmotors.The issue is to control these motors to give the required speed and torque

A simple equation: Power is the product of Torque and Angular velocityP = . This implies that if we want more torque (pulling capacity) fromthesame motor we may have to sacrifice speed and vice versaThe dc motors (tape motors) available have very high speed of rotationwhichis generally not needed. But what they lack is torque output. For reductionin speed and increase in pulling capacity we use pulley or gear systems.These are governed by: 1 X r1 = 2 X r2

Wheeled Locomotion Systems1. Differential drive2. Ackerman drive (Car type)3. Skid steer drive4. Articulated drive5. Synchronous drive6. Pivot drive


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Differential drive:This is the most commonly used form of locomotion system used in mobilerobots as its the simplest and easiest to implement.It has a free moving

wheel in the front accompanied with a left and right wheel. The two wheelsare separately powered when the wheels move in the same direction themachine moves in that direction. Turning is achieved by making the wheelsoppose each others motion, thus generating a couple

Fig.6: Differential drive in different working modes Blue arrows denote the direction of wheel. The green ones show robotmovement In-place (zero turning radius) rotation is done by turning the drive

wheels at the same rate in the opposite direction Arbitrary motion paths can be implemented by dynamically modifying theangular velocity and/or direction of the drive wheels Total of two motors are required, both of them are responsible fortranslation and rotational motion Simplicity and ease of use makes it the most preferred system bybeginners Independent drives make it difficult for straight line motion. Thedifferences in motors and frictional profile of the two wheels cause them to

move with slight turning effect The above drawback must be countered with appropriate feedbacksystem.Suitable for human controlled remote robots

Ackerman Drive:This is the car type drive and the most common in real world but not inrobot world. It is characterized by a pair of driving wheels and a separatepair of steering wheels. The translation and rotation are independent of

each other. However, translation and rotation are interlinked hence thissystem faces severe path planning problem.

Fig.7: Ackerman Drive in working modesArticulated Drive: In this mechanism, the machine chassis (body) is


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deformedto achieve rotation in contrast to the steering wheels in car type drive.

Fig.8: Articulated Drive In working modes

Two actuators (motors) are needed. One to drive the wheels and the othertochange the pivot angle. This system shares most of its features with thecartype mechanism, this is too an example of Non Holonomic System.

Pivot Drive:The unique type of Locomotion system. It is composed of a four wheeledchassis and a platform that can be raised or lowered.

Fig.9: Pivot DriveThe wheels are driven by a motor for translation motion in a straight linefor rotation one motor is needed to lower/raise the platform & another to

rotate the chassis around the platform. This system can guarantee perfectstraight line motion as well as accurate in place turns to a desiredheading.

Increasing Torque Using Pulleys:

Fig.10: Pulley system

1r1 = 2r2 => 2 = 1r1 / r211 = 22 => 2 = 11 / 2 => 2 = 1r2 / r1Thus we get reduction in speed and increased torque. Hence our machineisable to cross over obstacles easily and also pull more loads.

Multi Pulley Systems:


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Fig.11: Multi pulley system1r1 = 3r2 , => 3 = 1r1 / r2

11 = 33 , => 3 = 11 / 3, => 3 = 1r2 / r13r1 = 2r2 => 2 = 3r1 /Hence for n pulley system => 2 = 1r2n / r1n r222 = 33 => 2 = 33 / 2 => 2 = 3r2 / r1 => 2 = 1r22 / r12

7. GEAR SYSTEMGears are the most common form of torque increment devices, found inalmostall mechanical machines. The concept of reducing the rotation speed to

increase torque is known as Gear Reduction. A high-speed motor with lowtorque is used to drive heavier loads at lower speeds. They have muchmoreefficiency than pulleys. The maximum torque capability is not limited byfriction but material strength.A gear or more correctly a "gear wheel" is a rotating machine part havingcut teeth, or cogs, which mesh with another toothed part in order totransmit torque. Two or more gears working in tandem are called atransmission and can produce a mechanical advantage through a gear ratio

andthus may be considered a simple machine. Geared devices can change thespeed, magnitude, and direction of a power source. The most commonsituationis for a gear to mesh with another gear; however, a gear can also mesh anon-rotating toothed part, called a rack, thereby producing translationinstead of rotation.

Uses of Gear Systems:

Gear Reduction to increase torque / decrease speed of rotation.Alter thedirection of rotation axis.Synchronization to two axes.Reversal of directionof rotation.Types of Gears:Spur GearsHelical GearsBevel Gears


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Worm GearsRack and Pinion Gears

Spur Gears:

Very common kind of Gear Used primarily for gear reduction. Reductionratiois the ratio of teeth in the driver gear and the driven gear.

Fig12. Spur gearsHelical Gears:These gears have better grip on each other than the spur gears can alsobeused for changing the axis direction.

Fig13 (a), (b): Helical gears.

Bevel Gears:Mostly used for altering the direction of the rotation axis the gearreduction can be achieved by different number of teeth in the gears

Fig14 (a) (b):-bevel gearsWorm Wheel Mechanism:Used for very high gear reduction, The wheel is driven by the wormScrew. One rotation of the worm causes wheel to advance one tooth.

Fig.15: Worm wheel gearRack & Pinion Mechanism:They are used for converting rotational Motion into linear motion

Fig.16: Rack & pinion gear8. SENSORS


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A sensor is a device that measures a physical quantity and converts it intoa signal, which can be read by an observer or by an instrument. Forexample,

a mercury-in-glass thermometer converts the measured temperature intoexpansion and contraction of a liquid, which can be read on a calibratedglass tube. A thermocouple converts temperature to an output voltage,whichcan be read by a voltmeter. For accuracy, most sensors are calibratedagainst known standards. In other words, we can say that sensor is adevice,which receives and responds to a signal.

Fig.17: Thermocouple sensorSensors are used in everyday objects such as touch-sensitive elevatorbuttons (tactile sensor) and lamps, which dim or brighten by touching thebase. There are also innumerable applications for sensors of which mostpeople are never aware.Applications include cars, machines, aerospace, medicine, manufacturing,androbotics.

Types of Sensors:1. LDR (Light Dependent Resistor)2. Thermistor3. IR Sensor

LDR (Light Dependent Register):This is an electronic device that works on the principal of light when thelight fall on then it becomes in working otherwise it becomes in off statein robotics the light dependent register is used as a sensor.

The basic diagram of LDR is shown below:-

Fig.18: (a).Basic view of LDR (b).Symbol of LDR (c).LDRThermistor:A thermistor is a type of resistor whose resistance varies significantlywith temperature, more so than in standard resistors. The word is a


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portmanteau of thermal and resistor. Thermistors are widely used as inrushcurrent limiters, temperature sensors, self-resetting over currentprotectors, and self-regulating heating elements.Thermistors differ from resistance temperature detectors (RTD) in that the

material used in a Thermistor is generally a ceramic or polymer, whileRTDsuse pure metals. The temperature response is also different; RTDs areusefulover larger temperature ranges, while thermistors typically achieve ahigherprecision within a limited temperature range [usually 90 C to 130 C].

Fig.19: Thermistor symbol

Assuming, as a first-order approximation, that the relationship betweenresistance and temperature is linear, then:

WhereR = change in resistanceT = change in temperaturek = first-order temperature coefficient of resistanceIR Sensor:

These are the infrared sensor and they are generally used in robotics.

Fig.20: Different types IR sensors

9. Control systemA control system is a device or set of devices to manage, command, directorregulate the behavior of other devices or systems.There are two common classes of control systems, with many variations

andcombinations: logic or sequential controls, and feedback or linear controls.There is also fuzzy logic, which attempts to combine some of the designsimplicity of logic with the utility of linear control. Some devices orsystems are inherently not controllable.The term "control system" may be applied to the essentially manualcontrols


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that allow an operator, for example, to close and open a hydraulic press,perhaps including logic so that it cannot be moved unless safety guards arein place.

Fig.21: Control SystemAn automatic sequential control system may trigger a series of mechanicalactuators in the correct sequence to perform a task. For example variouselectric and pneumatic transducers may fold and glue a cardboard box, fillit with product and then seal it in an automatic packaging machine.In the case of linear feedback systems, a control loop, including sensors,control algorithms and actuators, is arranged in such a fashion as to try toregulate a variable at a set point or reference value. An example of thismay increase the fuel supply to a furnace when a measured temperature

drops.PID controllers are common and effective in cases such as this. Controlsystems that include some sensing of the results they are trying to achieveare making use of feedback and so can, to some extent, adapt to varyingcircumstances. Open-loop control systems do not make use of feedback,andrun only in pre-arranged ways.10. ActuatorsAn actuator is a mechanical device for moving or controlling a mechanism

orsystem. It is operated by a source of energy, usually in the form of anelectric current, hydraulic fluid pressure or pneumatic pressure, andconverts that energy into some kind of motion.Examples and applications:-Mechanical actuators operate by conversion of rotary motion into linearmotion, or vice versa. Conversion is commonly made via a few simple typesofmechanism including:

Screw: Screw jack, ball screw and roller screw actuators all operate on theprinciple of the simple machine known as the screw. By rotating theactuator's nut, the screw shaft moves in a line. By moving the screw shaft,the nut rotates.Wheel and axle: Hoist, winch, rack and pinion, chain drive, belt drive,rigid chain and rigid belt actuators operate on the principle of the wheeland axle. By rotating a wheel/axle (e.g. drum, gear, pulley or shaft) a


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linear member (e.g. cable, rack, chain or belt) moves. By moving the linearmember, the wheel/axle rotates.In engineering, actuators are frequently used as mechanisms to introducemotion, or to clamp an object so as to prevent motion. In electronic

engineering, actuators are a subdivision of transducers. They are deviceswhich transform an input signal (mainly an electrical signal) into motion.Specific examples include: electrical motors, pneumatic actuators, hydraulicactuators, linear actuators, comb drive, piezoelectric actuators andamplified piezoelectric actuators, thermal bimorphs, micro mirror devicesand electro active polymers.Motors are mostly used when circular motions are needed, but can also beused for linear applications by transforming circular to linear motion witha bolt and screw transducer. On the other hand, some actuators are

intrinsically linear, such as piezoelectric actuators.11. Power supply

A power supply is a device that supplies electrical energy to one or moreelectric loads. The term is most commonly applied to devices that convertone form of electrical energy to another, though it may also refer todevices that convert another form of energy (e.g., mechanical, chemical,solar) to electrical energy. A regulated power supply is one that controlsthe output voltage or current to a specific value; the controlled value is

held nearly constant despite variations in either load current or thevoltage supplied by the power supply's energy source.Every power supply must obtain the energy it supplies to its load, as wellas any energy it consumes while performing that task, from an energysource.Depending on its design, a power supply may obtain energy from: Electrical energy transmission systems. Common examples of this includepower supplies that convert AC line voltage to DC voltage. Energy storage devices such as batteries and fuel cells.

Electromechanical systems such as generators and alternators. Solar power.A power supply may be implemented as a discrete, stand-alone device oras anintegral device that is hardwired to its load. In the latter case, forexample, low voltage DC power supplies are commonly integrated withtheir


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loads in devices such as computers and household electronics.

Commonly specified power supply attributes include: The amount of voltage and current it can supply to its load.

How stable its output voltage or current is under varying line and loadconditions. How long it can supply energy without refueling or recharging (applies topower supplies that employ portable energy sources)

Power supplies types:Power supplies for electronic devices can be broadly divided intoline-frequency (or "conventional") and switching power supplies. Theline-frequency supply is usually a relatively simple design, but it becomes

increasingly bulky and heavy for high-current equipment due to the needforlarge mains-frequency transformers and heat-sinked electronic regulationcircuitry. Conventional line-frequency power supplies are sometimes called"linear," but that is a misnomer because the conversion from AC voltage toDC is inherently non-linear when the rectifiers feed into capacitivereservoirs. Linear voltage regulators produce regulated output voltage bymeans of an active voltage divider that consumes energy, thus makingefficiency low. A switched-mode supply of the same rating as a

line-frequency supply will be smaller, is usually more efficient, but willbe more complex.DC power supplyAn AC powered unregulated power supply usually uses a transformer toconvertthe voltage from the wall outlet (mains) to a different, nowadays usuallylower, voltage. If it is used to produce DC, a rectifier is used to convertalternating voltage to a pulsating direct voltage, followed by a filter,comprising one or more capacitors, resistors, and sometimes inductors, to

filter out (smooth) most of the pulsation. A small remaining unwantedalternating voltage component at mains or twice mains power frequency(depending upon whether half- or full-wave rectification is used)rippleisunavoidably superimposed on the direct output voltage.For purposes such as charging batteries the ripple is not a problem, andthesimplest unregulated mains-powered DC power supply circuit consists of a


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transformer driving a single diode in series with a resistor.

Fig.22: Circuit diagram of dc power supply

Before the introduction of solid-state electronics, equipment used valves(vacuum tubes) which required high voltages; power supplies used step-uptransformers, rectifiers, and filters to generate one or more directvoltages of some hundreds of volts, and a low alternating voltage forfilaments. Only the most advanced equipment used expensive and bulkyregulated power supplies.

12. PHYSICAL INTERFACING DEVICESAn electrical connector is an electro-mechanical device for joining

electrical circuits as an interface using a mechanical assembly. Theconnection may be temporary, as for portable equipment, require a tool forassembly and removal, or serve as a permanent electrical joint betweentwowires or devices.There are hundreds of types of electrical connectors. Connectors may jointwo lengths of flexible copper wire or cable, or connect a wire or cable oroptical interface to an electrical terminal.In computing, an electrical connector can also be known as a physical

interface (compare Physical Layer in OSI model of networking). Cableglands,known as cable connectors in the U.S., connect wires to devicesmechanicallyrather than electrically and are distinct from quick-disconnects performingthe latter.Properties of electrical connectors:An ideal electrical connector would have a low contact resistance and highinsulation value. It would be resistant to vibration, water or other

contaminants, and pressure. It would be easily mated/unmated,unambiguouslypreserve the orientation of connected circuits, reliable, carry one ormultiple circuits. Desirable properties for a connector also include easyidentification, compact size, rugged construction, durability (capable ofmany connect/disconnect cycles), rapid assembly, simple tooling, and lowcost. No single connector has all the ideal properties. The proliferation of


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types is a reflection of the differing importance placed on the designfactors.Some of the interfacing devices are:1. USB Connector (Universal Serial Bus)

2. CAT5 (Category 5)3. VGA Connector (Video Graphics Array)4. BNC Connector (Bayonet NeillConcelman)5. HDMI (High Definition Multimedia Interface)6. DVI (Digital Visual Interface)

USB Connector (Universal Serial Bus):USB (Universal Serial Bus) is an industry standard developed in themid-1990s that defines the cables, connectors and protocols used for

connection, communication and power supply between computers andelectronicdevices.USB was designed to standardise the connection of computer peripherals,suchas keyboards, pointing devices, digital cameras, printers, portable mediaplayers, disk drives and network adapters to personal computers, both tocommunicate and to supply electric power. It has become commonplace onother

devices, such as smartphones, PDAs and video game consoles. USB haseffectively replaced a variety of earlier interfaces, such as serial andparallel ports, as well as separate power chargers for portable devices.

Fig 23: Standard type A plug and receptacle

CAT 5 (CATEGORY 5):Category 5 cables (Cat 5) is a twisted pair cable for carrying signals. This

type of cable is used in structured cabling for computer networks such asEthernet. It is also used to carry other signals such as telephony andvideo. The cable is commonly connected using punch down blocks andmodularconnectors. Most Category 5 cables are unshielded, relying on the twistedpair design and differential signaling for noise rejection.


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Fig 24: Category 5 patch cable in T568B wiring

VGA Connector (Video Graphics Array):A Video Graphics Array (VGA) connector is a three-row 15-pin DE-15

connector. The 15-pin VGA connector is found on many video cards,computermonitors, and some high definition television sets. On laptop computers orother small devices, a mini-VGA port is sometimes used in place of thefull-sized VGA connector.

Fig 25: A VGA Cable

BNC Connector (Bayonet NeillConcelman):The BNC connector (Bayonet NeillConcelman) is a common type of RFconnectorused for coaxial cable. It is used with radio, television, and otherradio-frequency electronic equipment, test intstruments, video signals, andwas once a popular computer network connector. BNC connectors aremade tomatch the characteristic impedance of cable at either 50 ohms or 75 ohms.It

is usually applied for frequencies below 3 GHz and voltages below 500Volts.

Fig 26: Male 50 ohm BNC connector

HDMI (High Definition Multimedia Interface):High-Definition Multimedia Interface (HDMI) is a compact audio/videointerface for transmitting uncompressed digital data. It is a digitalalternative to consumer analog standards, such as radio frequency (RF)

coaxial cable, composite video, S-Video, SCART, component video, D-Terminal,or VGA. HDMI connects digital audio/video sources (such as set-top boxes,DVD players, HD DVD players, Blu-ray Disc players, AVCHD camcorders,personal computers (PCs), video game consoles such as the PlayStation 3andXbox 360, and AV receivers) to compatible digital audio devices, computer


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monitors, video projectors, tablet computers, and digital televisions.

Fig 27: HDMI standard connectorDVI (Digital Visual Interface):

The Digital Visual Interface (DVI) is a video interface standard coveringthe transmission of video between a source device (such as a personalcomputer) and a display device. The DVI standard has achievedwidespreadacceptance in the PC industry, both in desktop PCs and monitors. Mostcontemporary retail desktop PCs and LCD monitors feature a DVI interface,and many other devices (such as projectors and consumer televisions)supportDVI indirectly through HDMI, another video interface standard. Most

laptopsstill have legacy VGA and, in some models, HDMI ports, but fewer haveDVI.

Fig 28: A male DVI-D (single link) connector

13. CONCLUSIONRobotics means the study and application of robot technology. The goal of

robotics is to mimic natural world as closely as possible. The main elementsin the robot are the moving elements and the sensorsEvolution of robots, the elements of robotics, the limitation of robots andthe various applications of robots. In the application part this paperexpects to cover in detail robosurgery and robonauts (the robots used inspace).Thus, learning from basic knowledge of robotics and applying theminassembling a robot helped clearing many quest of knowledge and so manyqueries. The most important part was the concepts of basic electronics to

the circuit diagram, practicing soldering and which helped in developing thegrounds of building a basic robot.Additionally, it helped in boosting confidence for working in higher coreelectronics based industries in the near future.


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14. BIBLIOGRAPHY

1.http://www.omegaelectronics.net/profile.asp2.http://electronics.howstuffworks.com/robot.htm

3.http://engineering-ed.org/Robotics/documents.4.http://html.alldatasheet.com/html5.http://en.wikipedia.org/
http://www.omegaelectronics.net/profile.asphttp://www.omegaelectronics.net/profile.asphttp://www.omegaelectronics.net/profile.asphttp://electronics.howstuffworks.com/robot.htmhttp://electronics.howstuffworks.com/robot.htmhttp://electronics.howstuffworks.com/robot.htmhttp://engineering-ed.org/Robotics/documentshttp://engineering-ed.org/Robotics/documentshttp://engineering-ed.org/Robotics/documentshttp://html.alldatasheet.com/htmlhttp://html.alldatasheet.com/htmlhttp://html.alldatasheet.com/htmlhttp://www.facebook.com/l.php?u=http%3A%2F%2Fen.wikipedia.org%2F&h=uAQFHf2lt&s=1http://www.facebook.com/l.php?u=http%3A%2F%2Fen.wikipedia.org%2F&h=uAQFHf2lt&s=1http://www.facebook.com/l.php?u=http%3A%2F%2Fen.wikipedia.org%2F&h=uAQFHf2lt&s=1http://www.facebook.com/l.php?u=http%3A%2F%2Fen.wikipedia.org%2F&h=uAQFHf2lt&s=1http://html.alldatasheet.com/htmlhttp://engineering-ed.org/Robotics/documentshttp://electronics.howstuffworks.com/robot.htmhttp://www.omegaelectronics.net/profile.asp

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