Dc Servo Motor Position System

8/10/2019 Dc Servo Motor Position System

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ABSTRACT

This paper presents the position control of a DC servo motor using discrete

electronic component built around the ever familiar LM741 operational amplifier.

Servo systems are generally controlled by conventional Proportional Integral

Derivative (PID) controllers. PID controller is a feed-back loop unit in the

industries control. The controller receives the command, subtracts it with the actual

value to create a difference. This difference is then used to calculate a new input

value which allows the data of system to achieve or maintain at the reference

value. Our design focuses on low cost semiconductor component which makes it

direct in its approach. Here a feedback loop built around an operational amplifier

maintains the system stability as well as controlling the position of the motors.


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CHAPTER ONE

INTRODUCTION

Preamble

A servomechanism, sometimes shortened to servo, is an automatic device that uses

error-sensing negative feedback to correct the performance of a mechanism.

The term correctly applies only to systems where the feedback or error-correction

signals help control mechanical position, speed or other parameters. For example,

an automotive power window control is not a servomechanism, as there is no

automatic feedback that controls positionthe operator does this by observation.

By contrast a car's cruise control uses closed loop feedback, which classifies it as a

servomechanism.

This chapter will provide information basic to understanding servo systems and

their components.

The Open-Loop Control Systemis controlled directly, and only by an input

signal. It has no feedback and is therefore less accurate than the closed-loop

control system. The open-loop system usually requires an operator to control the

speed and direction of movement of the output.


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The Closed-Loop Control Systemis the most common type used in the Navy. It

can respond and move loads quickly and with greater accuracy than the open-loop

system. The closed-loop system has an automatic feedback system that informs the

input that the desired movement has taken place.

The Servo Systemis classified as a closed- loop system when it is capable of:

Accepting an order and defining the desired result, evaluating present

conditions.

Comparing the desired result with present conditions and obtaining a

difference or an error signal.


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Issuing a correcting order, and changing the existing conditions to the

desired result, and Obeying the correcting order.

The Basic Servo Systemis normally made up of electromechanical parts, and

consists of a synchro-control system, servo amplifier, servo motor, and some form

of feedback.

The Position Servohas the goal of controlling the position of the load. In the ac

position servo system, the amplitude and phase of the ac error signal determine the

amount and direction the load will be driven.

In the dc position servo system, the amplitude and polarity of the dc error signal

are used to determine the amount and direction the load will be driven.


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The Velocity Servois based on the same principle of error-signal generation as the

position servo, except that the VELOCITY of the output is sensed rather than

position of the load. When the velocity loop is at correspondence, an error signal is

still present, and the load is moving at the desired velocity.

The Acceleration Servois similar to the velocity and position servos except that

the acceleration of the load is being sensed rather than the position or velocity. In

this loop, the tachometer of the velocity loop is replaced with an accelerometer.

Purpose of Servomechanism:

Accurate control of motion without the need for human attendants

(automatic control),


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Maintenance of accuracy with mechanical load variations, changes in the

environment, power supply fluctuations, and aging and

deterioration of components (regulation and self- calibration),

Control of a high-power load from a low-power command signal (power

amplification) and,

Control of an output from a remotely located input, without the use of

mechanical linkages.

Applications

Servomechanisms are useful to control motion without human attendants, or to

maintain the accuracy of an environment like a power plant, and to control action

from a remote isolated station. The controller typically uses (and has) much less

power than that of what is being controlled. Almost always it is the position or

velocity which is being controlled.

Servomechanisms are used to control mechanical things such as motors, steering

mechanisms, and robots. Servomechanisms are used extensively in robotics. A

robot controller can tell a servomechanism to move in certain ways that depend on

the inputs from sensors. Multiple servomechanisms, when interconnected and

controlled by a sophisticated computer, can do complex tasks such as cook a meal.

A set of servomechanisms, including associated circuits and hardware, and


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intended for a specific task, constitutes a servo system. Servo systems do precise,

often repetitive, mechanical chores. A computer can control a servo system made

up of many servomechanisms. For example, an unmanned robotic warplane (also

known as a drone) can be programmed to take off, fly a mission, return, and land.

Servo systems can be programmed to do assembly-line work and other tasks that

involve repetitive movement, precision, and endurance.

A servo robot is a robot whose movement is programmed into a computer. The

robot follows the instructions given by the program, and carries out precise

motions on that basis. Servo robots can be categorized according to the way they

move. In continuous-path motion, the robot mechanism can stop anywhere along

its path. In point-to-point motion, it can stop only at specific points in its path.

Servo robots can be easily programmed and reprogrammed. This might be done by

exchanging diskettes, by manual data entry, or by more exotic methods such as a

teach box. When a robot arm must perform repetitive, precise, complex motions,

the movements can be entered into the robot controllers memory. Then,when the

memory is accessed, the robot arm goes through all the appropriate movements. A

teach box is a device that detects and memorizes motions or processes for later

recall.


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The constant speed control system of a DC motor is a servomechanism that

monitors any variations in the motors speed so that it can quickly and

automatically return the speed to its correct value. Servomechanisms are also used

for the control systems of guided missiles, aircraft, and manufacturing.

The power steering system in an automobile is an example of a servomechanism.

The direction of the front wheels is controlled by the angle of the steering wheel.

Should the motion of the car turn the front wheels away from the desired direction,

the servomechanism, consisting of a mechanical and hydraulic system,

automatically brings the wheels back to the desired direction. Another example of

a servomechanism is the automatic control system by which a THERMOSTAT,

(q.v.) in one of the rooms of a house controls the heat output of the heating

furnace. Other examples include automatic pilots used on ships, aircraft, and space

vehicles, in which the direction of motion of the vehicle is controlled by a compass

setting. Unmanned spacecraft are automatically turned to point their cameras, radio

antennae, and solar panels in the desired directions by servomechanisms. The input

in that case is the sensing of the direction of the sun and stars, and the output is the

control of small jets that turn and orient the spacecraft.


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A common type of servo provides position control. Servos are commonly electrical

or partially electronic in nature, using an electric motor as the primary means of

creating mechanical force. Other types of servos use hydraulics, pneumatics, or

magnetic principles. Usually, servos operate on the principle of negative feedback,

where the control input is compared to the actual position of the mechanical system

as measured by some sort of transducer at the output. Any difference between the

actual and wanted values (an error signal) is amplified and used to drive the

system in the direction necessary to reduce or eliminate the error. An entire science

known as control theory has been developed on this type of system.

Servomechanisms were first used in military fire-control and marine navigation

equipment. They were also used in military applications, such as an antiaircraft

gun that tracks a plane via radar. As the plane moves the radar gives the planes

position information to the gun, which computes the new position of the plane and

realigns. This process can go indefinitely. Some other applications are satellite

tracking and satellite antenna alignment systems, automatic machine tools, star-

tracking systems on telescopes (since the stars position changes as the earth

rotates), and navigation systems.


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Another device commonly referred to as a servo is used in automobiles to amplify

the steering or braking force applied by the driver. However, these devices are not

true servos, but rather mechanical amplifiers.

Today servomechanisms are used in automatic machine tools, satellite-tracking

antennas, and remote control airplanes, automatic navigation systems on boats and

planes, and antiaircraft-gun control systems. Other examples are fly-by-wire

systems in aircraft which use servos to actuate the aircrafts control surfaces, and

radio-controlled models which use RC servos for the same purpose. Many

autofocus cameras also use a servomechanism to accurately move the lens, and

thus adjust the focus. A modern hard disk drive has a magnetic servo system with

sub-micrometre positioning accuracy.

THE PID CONTROLLER

What basic components are needed for a servo system? Many look similar to the

circuit below. The error amp gives you a constant reality check. How? It compares

where you want to go, Vset, with where you're at now, Vsensor, by calculating the

difference between the two, Verr = Vset - Vsensor. The PID controller takes this

error and determines the drive voltage applied to the process in an attempt to bring

Vset = Vsensor or Verr = 0.


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The terms defined: P -Proportional, I - Integral, D - Derivative. These terms

describe three basic mathematical functions applied to the error signal, Verror =

Vset - Vsensor. This error represents the difference between where you want to go

(Vset), and where you're actually at (Vsensor). The controller performs the PID

mathematical functions on the error and applies their sum to a process (motor,

heater, etc.) So simple, yet so powerful! If tuned correctly, the signal Vsensor

should move closer to Vset.

Tuning a system means adjusting three multipliers Kp, Ki and Kd adding in

various amounts of these functions to get the system to behave the way you want.

The table below summarizes the PID terms and their effect on a control system.


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Term

Math

Function

Ef fect on Contr ol System

P

Proportional

KP x Verror

Typically the main drive in a control loop, KP

reduces a large part of the overall error.

I

Integral

KI x Verror

dt

Reduces the final error in a system. Summing

even a small error over time produces a drive

signal large enough to move the system

toward a smaller error.

D

Derivative

KD x dVerror

/ dt

Counteracts the KP and KI terms when the

output changes quickly. This helps reduce

overshoot and ringing. It has no effect on

final error.

ERROR AMPLI FI ER. A classic circuit for calculating the error is asumming op

amp.In the controller, XOP1 performs the error calculation. Remembering that the

summing amp is an inverting amp, we calculate its output using R1 = R2 = R3 =

10 k.
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Verr=-(Vset/R1+Vsensor/R2) R3

=(Vset+Vsensor) (10k/10k)

= - (Vset + Vsensor )

But how does the summer calculate a difference? Well, it does require that your

sensor circuit produce a negative output voltage. Assuming that Vsensoris the

negative of the actual sensor voltage Vsensor= - Vsens, you get the difference.

Verr = -( Vset - Vsens )

You can look at the error amp's function this way. When Vsensoris exactly the

negative of Vset, the currents through R1 and R2, equal and opposite, cancel each

other as they enter the op amps's summing junction. You end up with zero current

through R3 and of course 0V, or zero error, at the output. Any difference between

Vset and -Vsensor, results in an error voltage at the output that the PID controller

can act upon.


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CHAPTER TWO

LITERATURE REVIEW

History

James Watt's steam engine governor is generally considered the first powered

feedback system. The windmill fantail is an earlier example of automatic control,

but since it does not have an amplifier or gain, it is not usually considered a

servomechanism.

The first feedback position control device was the ship steering engine, used to

position the rudder of large ships based on the position of the ship's wheel. This

technology was first used on the SS Great Eastern in 1866. Steam steering engines

had the characteristics of a modern servomechanism: an input, an output, an error

signal, and a means for amplifying the error signal used for negative feedback to

drive the error towards zero. The Ragonnet power reverse mechanism was a

general purpose air or steam-powered servo amplifier for linear motion patented in

1909.

Electrical servomechanisms were used as early as 1888 in Elisha Gray's

Telautograph.

Electrical servomechanisms require a power amplifier. World War II saw the

development of electrical fire-control servomechanisms, using an amplidyne as the


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power amplifier. Vacuum tube amplifiers were used in the UNISERVO tape drive

for the UNIVAC I computer. The Royal Navy began experimenting with Remote

Power Control (RPC) on HMS Champion in 1928 and began using RPC to control

searchlights in the early 1930s. During WW2 RPC was used to control gun mounts

and gun directors.

Modern servomechanisms use solid state power amplifiers, usually built from

MOSFET or thyristor devices. Small servos may use power transistors.

The origin of the word is believed to come from the French "Le Servomoteur" or

the slavemotor, first used by J. J. L. Farcot in 1868 to describe hydraulic and steam

engines for use in ship steering.

The simplest kind of servo use bangbang control. More complex control systems

use proportional control, PID control, and state space control, which are studied in

modern control theory.

Although control systems of various types date back to antiquity, a more formal

analysis of the field began with a dynamics analysis of the centrifugal governor,

conducted by the physicist James Clerk Maxwell in 1868, entitled On Governors.

This described and analyzed the phenomenon of "hunting", in which lags in the

system may lead to overcompensation and unstable behavior. This generated a


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flurry of interest in the topic, during which Maxwell's classmate, Edward John

Routh, abstracted Maxwell's results for the general class of linear systems.

Independently, Adolf Hurwitz analyzed system stability using differential

equations in 1877, resulting in what is now known as the RouthHurwitz theorem.

A notable application of dynamic control was in the area of manned flight. The

Wright brothers made their first successful test flights on December 17, 1903 and

were distinguished by their ability to control their flights for substantial periods

(more so than the ability to produce lift from an airfoil, which was known).

Continuous, reliable control of the airplane was necessary for flights lasting longer

than a few seconds.

By World War II, control theory was an important part of fire-control systems,

guidance systems and electronics. Sometimes mechanical methods are used to

improve the stability of systems. For example, ship stabilizers are fins mounted

beneath the waterline and emerging laterally. In contemporary vessels, they may be

gyroscopically controlled active fins, which have the capacity to change their angle

of attack to counteract roll caused by wind or waves acting on the ship.

The Sidewinder missile uses small control surfaces placed at the rear of the missile

with spinning disks on their outer surfaces; these are known as rollerons. Airflow

over the disks spins them to a high speed. If the missile starts to roll, the


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gyroscopic force of the disks drives the control surface into the airflow, cancelling

the motion. Thus, the Sidewinder team replaced a potentially complex control

system with a simple mechanical solution.

The Space Race also depended on accurate spacecraft control, and control theory

has also seen an increasing use in fields such as economics.


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CHAPTER THREE

METHODOLOGY

RESEARCH METHOD

Basically, research on this project was done both on the internet and on various

Electrical/Electronic textbooks. The circuit is built around discrete electronics

components including resistors, capacitors, transistors and as the microcontroller as

the core.

COMPONENTS DESCRIPTION

RESISTOR

Resistors are one of the most common components in an electronic circuit. The

basic operation is to limit the flow of current in the circuit. Many resistor values

were used in this project. Some of them include 1K, 10k, 100 and the 330

used to limit the current that flows to the seven segment display.

How to read Resistor Color Codes

First find the tolerance band, it will typically be gold (5%) and sometimes silver

(10%). Starting from the other end, identify the first band - write down the number

Fig 3.1Resistor color code


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associated with that color; in this case Brown is 1. Now 'read' the next color, here it

is Black so write down a '0' next to the six. (You should have '10' so far.) Now read

the third or 'multiplier exponent' band and write down that as the number of zeros.

In this example it is two so we get '1000'. If the 'multiplier exponent' band is Black

(for zero) don't write any zeros down.

If the 'multiplier exponent' band is Gold move the decimal point one to the left. If

the 'multiplier exponent' band is Silver move the decimal point two places to the

left. If the resistor has one more band past the tolerance band it is a quality band.

BS 1852 Coding for resistor values

The letter R is used for Ohms and K for Kohms M for Megohms and placed where

the decimal point would go.

At the end is a letter that represents tolerance Where M=20%, K=10%, J=5%,

G=2%, and F=1% D=.5% C=.25 B=.1%

CAPACITOR

Capacitors store electric charge. They are used with resistors in timing circuits

because it takes time for a capacitor to fill with charge. They are used to smooth

varying DC supplies by acting as a reservoir of charge. They are also used in filter

circuits because capacitors easily pass AC (changing) signals but they block DC

(constant) signals. There are many types of capacitor but they can be split into two

groups, polarized and unpolarised. Each group has its own circuit symbol.

Electrolytic Capacitors


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Electrolytic capacitors are polarized and they must be connected the correct way

round, at least one of their leads will be marked + or -. They are not damaged by

heat when soldering.

There are two designs of electrolytic capacitors; axial where the leads are attached

to each end (220F in picture) and radial where both leads are at the same end

(10F in picture). Radial capacitors tend to be a little smaller and they stand

upright on the circuit board. It is easy to find the value of electrolytic capacitors

because they are clearly printed with their capacitance and voltage rating. The

voltage rating can be quite low (6V for example) and it should always be checked

when selecting an electrolytic capacitor.

Non-polarized capacitors

Small value capacitors are non-polarized and may be connected either way round.

They are not damaged by heat when soldering, except for one unusual type

(polystyrene). They have high voltage ratings of at least 50V, usually 250V or so.

It can be difficult to find the values of these small capacitors because there are

many types of them and several different labeling systems!

Fi 1.5Electrol tic Ca acitors


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Many small value capacitors have their value printed but without a multiplier, so

you need to use experience to work out what the multiplier should be.

TRANSISTORS

Transistors are made from semiconductors. These are materials, such as silicon or

germanium, that are doped (have minute amounts of foreign elements added) so

that either an abundance or a lack of free electrons exists. In the former case, the

semiconductor is called n-type, and in the latter case, p-type. By combining n-type

and p-type materials, a diode can be produced. When this diode is connected to a

battery so that the p-type material is positive and the n-type negative, electrons are

repelled from the negative battery terminal and pass unimpeded to the p-region,

which lacks electrons. With battery reversed, the electrons arriving in the p-

material can pass only with difficulty to the n-material, which is already filled with

free electrons, and the current is almost zero.

The bipolar transistor was invented in 1948 as a replacement for the triode vacuum

tube. It consists of three layers of doped material, forming two p-n (bipolar)

junctions with configurations of p-n-p or n-p-n. One junction is connected to a

battery so as to allow current flow (forward bias), and the other junction has a

battery connected in the opposite direction (reverse bias). If the current in the

forward-biased junction is varied by the addition of a signal, the current in the

reverse-biased junction of the transistor will vary accordingly. The principle can be

used to construct amplifiers in which a small signal applied to the forward-biased

junction causes a large change in current in the reverse-biased junction.

Another type of transistor is the field-effect transistor (FET). Such a transistor

operates on the principle of repulsion or attraction of charges due to a

superimposed electric field. Amplification of current is accomplished in a manner


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similar to the grid control of a vacuum tube. Field-effect transistors operate more

efficiently than bipolar types, because a large signal can be controlled by a very

small amount of energy.

Transistors function majorly as switch or amplifiers. To function as a switch, the

transistor has to be biased into saturation i.e. the base voltage exceeds 0.7v for

silicon type and 0.3v for germanium type. On the other hand, the base voltage can

be varied continually by an input signal for the transistor to function as an

amplifier. The transistors in this circuit are all Field Effect Transistors (FET) and

they function as high speed switches.

DIODE

This is an electronic device that allows the passage of current in only one direction.

The first such devices were vacuum-tube diodes, consisting of an evacuated glass

or steel envelope containing two electrodesa cathode and an anode. Because

electrons can flow in only one direction, from cathode to anode, the vacuum-tube

diode could be used as a rectifier. The diodes most commonly used in electronic

circuits today are semiconductor diodes. The simplest of these, the germanium

point-contact diode, dates from the early days of radio, when the received radio

signal was detected by means of a germanium crystal and a fine, pointed wire that

rested on it. In modern germanium (or silicon) point-contact diodes, the wire and a

tiny crystal plate are mounted inside a small glass tube and connected to two wires

that are fused into the ends of the tube.


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OPERATIONAL AMPLIFIER

An operational amplifier (op-amp) is a DC-coupled high-gain electronic voltage

amplifier with a differential input and, usually, a single-ended output. In this

configuration, an op-amp produces an output potential (relative to circuit ground)

that is typically hundreds of thousands of times larger than the potential difference

between its input terminals.

Operational amplifiers had their origins in analog computers, where they were used

to do mathematical operations in many linear, non-linear and frequency-dependent

circuits. Characteristics of a circuit using an op-amp are set by external

components with little dependence on temperature changes or manufacturing

variations in the op-amp itself, which makes op-amps popular building blocks for

circuit design.

Op-amps are among the most widely used electronic devices today, being used in a

vast array of consumer, industrial, and scientific devices. Many standard IC op-

amps cost only a few cents in moderate production volume. Op-amps may be

packaged as components, or used as elements of more complex integrated circuits.

The op-amp is one type of differential amplifier. Other types of differential

amplifier include the fully differential amplifier (similar to the op-amp, but with

two outputs), the instrumentation amplifier (usually built from three op-amps), the


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isolation amplifier (similar to the instrumentation amplifier, but with tolerance to

common-mode voltages that would destroy an ordinary op-amp), and negative

feedback amplifier (usually built from one or more op-amps and a resistive

feedback network).

HOW IT WORKS

Generically, the word servo is short for servomechanism, which refers to any self-

regulating feedback system. A servo is usually an active element used in feedback

in order to null or reduce an amplifier's offset voltage.

A Servo is a small device that has an output shaft which can be positioned to

specific angular positions by sending the servo a coded signal. As long as the

coded signal exists on the input line, the servo will maintain the angular position of

the shaft. As the coded signal changes, the angular position of the shaft changes. In

practice, servos are used in radio controlled airplanes to position control surfaces

like the elevators and rudders. They are also used in radio controlled cars, puppets,

and of course, robots. The servo motor has some control circuits and a

potentiometer (a variable resistor, aka pot) that is connected to the output shaft. In

the circuit above, the pot can be seen on the right side of the circuit board. This pot

allows the control circuitry to monitor the current angle of the servo motor. If the

shaft is at the correct angle, then the motor shuts off. If the circuit finds that the

angle is not correct, it will turn the motor the correct direction until the angle is


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correct. The output shaft of the servo is capable of travelling somewhere around

180 degrees. Usually, its somewhere in the 210 degree range, but it varies by

manufacturer. A normal servo is used to control an angular motion of between 0

and 180degrees. A normal servo is mechanically not capable of turning any farther

due to a mechanical stop built on to the main output gear. The amount of power

applied to the motor is proportional to the distance it needs to travel. So, if the

shaft needs to turn a large distance, the motor will run at full speed. If it needs to

turn only a small amount, the motor will run at a slower speed. This is called

proportional control. How do you communicate the angle at which the servo

should turn? The control wire is used to communicate the angle. The angle is

determined by the duration of a pulse that is applied to the control wire. This is

called Pulse Coded Modulation. The servo expects to see a pulse every 20

milliseconds (.02 seconds) the length of the pulse will determine how far the motor

turns. A 1.5 millisecond pulse, for example, will make the motor turn to the 90

degree position (often called the neutral position) if the pulse is shorter than 1.5ms,

then the motor will turn the shaft to closer to 0 degrees. If the pulse is longer than

1.5ms, the Servo motors are used in closed loop control systems in which work is

the control variable. The servo motor controller directs operation of the servo

motor by sending velocity command signals to the amplifier, which drives the

servo motor. An integral feedback device (resolver) or devices (encoder and


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tachometer) are either incorporated within the servo motor or are remotely

mounted, often on the load itself. These provide the servo motor's position and

velocity feedback that the controller compares to its programmed motion profile

and uses to alter its velocity signal. Servo motors feature a motion profile, which is

a set of instructions programmed into the controller that defines the servo motor

operation in terms of time, position, and velocity. The ability of the servo motor to

adjust to differences between the motion profile and feedback signals depends

greatly upon the type of controls and servo motors used.


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REFERENCES

[1] Devidas, A.R., Ramesh, M.V. Wireless Smart Grid Design for Monitoring and

Optimizing Electric Transmission in India, 2010 Fourth International Conference

on Sensor Technologies and Applications (SENSORCOMM), pp.637-640,2010.

[2] Shoeb S. Sheikh, et al., Design and Implementation of Wireless Automatic

Meter Reading System," International Journal of Engineering Science and

Technology, Vol. 3, No. 3, pp. 2329-2334, March 2011.

[3] Amit Jain and Mohnish Bagree, "A Prepaid Meter Using Mobile

Communication," International Journal of Engineering, Science and Technology,

Vol. 3, No. 3, pp. 160-166, Apr 2011.

[4] Kwan, B.H., Moghavvemi, M., PIC Based Smart Card Prepayment System,

Student Conference on Research and Development, pp. 440- 443, 2002.

[5] Khan R.H., T.F. Aditi, V. Sreeram and H.H.C. lu, A Prepaid Smart Metering

Scheme Based on WiMAX Prepaid Accounting Model, Smart Grid and

Renewable Energy, Vol. 1, No. 2, pp. 63-69, 2010.

[6] Ling Zou, Sihong Chu and Biao Guo.,The Design of Prepayment Polyphase

Smart Electricity Meter System, International Conference on Intelligent

Computing and Integrated Systems (ICISS), pp. 430-432, 22-24, Dec 2010.

[7] Richa Shrivastava and Nipun Kumar Mishra, "An Embedded System for

Wireless Prepaid Billing of Digital Energy Meter," International Journal of

Advances in Electronics Engineering, pp. 322-324.

[8] M.C. Ndinechi, O.A. Ogungbenro and K.C. Okafor, "Digital Metering System:

A Better Alternative for Electromechanical Energy Meter in Nigeria,"International

Journal of Academic Research , Vol. 3, No. 5, pp. 189-192, Sep 2011.


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[9] Loss, P et al., A Single Phase Microcontroller Based Energy Meter, IEEE

Instrumentation and Measurement Technology Conference. St. Paul Minnesota,

USA, May 18-21, 1998.

[10]. Atmel Corporation- Interfacing AT24CXX Serial EEPROMs withAT89CX051

Microcontrollers, www.atmel.com/, accessed on 11 March 2006

[11]. Atmel Corporation- AVR402:Hardware design considerations ,

www.atmel.com/,accessed on 28 March 2006

[12]. Future Technology Devices - AN232B-05 Configuring FT232R,FT2232C

and FT232BM Baud Rates , http://www.ftdichip.com ,accessed 16 March 2006

[13]. Future Technology Devices AN232R-02 FTDIChip-ID for the FT232R

and FT245R, http://www.ftdichip.com ,accessed 16 March 2006

[14]. Future Technology Devices FT232R USB UART I.C,

http://www.ftdichip.com ,accessed 16 March 2006
http://www.atmel.com/http://www.atmel.com/http://www.atmel.com/

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Dc Servo Motor Position System