MINI Project

Landmine Detecting Robot

INDEX

CONTENTS

1. Abbreviations

2. Figures locations

3. Abstract

4. Introduction

5. Block Diagram

6. Block Diagram Description

7. Schematic

8. Schematic Description

9. Hardware Components

10. Circuit Description

11. Software components

Embedded ‘C’

12. KEIL procedure description

13. Conclusion (or) Synopsis

14. Future Aspects

15. Bibliography

1


ABBREVATIONS:

Microcontroller:

Symbol Name

ACC Accumulator

B B register

PSW Program status word

SP Stack pointer

DPTR Data pointer 2 bytes

DPL Low byte

DPH High byte

P0 Port0

P1 Port1

P2 Port2

P3 Port3

IP Interrupt priority control

IE Interrupt enable control

TMOD Timer/counter mode control

TCON Timer/counter control

T2CON Timer/counter 2 control

T2MOD Timer/counter mode2 control

TH0 Timer/counter 0high byte

TL0 Timer/counter 0 low byte

TH1 Timer/counter 1 high byte


TH2 Timer/counter 2 high byte


SCON Serial control

SBUF Serial data buffer

PCON Power control

2



ABSTRACT

The robotics mainly aims at reduction of man-power by designing

automated systems. In the present scenario of increase in wars and terrorist activities,

unmanned systems play a very important role to minimize human losses. This

landmine detecting robot is one such automated unmanned system used for detecting

landmines.

The microcontroller forms the heart of the system with landmine

sensor, drivers and motors connected to it. These are used for moving the robot in

desired direction and detecting landmines present if any. The sensor detects the metal

(conductor) by using metal detector.

The system uses a battery for power supply. The buzzer is interfaced

with the microcontroller which goes on immediately on detection of metal by metal

detector. In stand-by mode the robot just moves in different directions.

This project finds its application for military purposes and policing

purposes.

3


1. INTRODUCTION

EMBEDDED SYSTEMS

Embedded systems are designed to do some specific task rather than be a

general-purpose computer for multiple tasks. Some also has real time performance

constraints that must be met, for reason such as safety and usability; others may have

low or no performance requirements, allowing the system hardware to be simplified to

reduce costs.

An embedded system is not always a separate block - very often it is

physically built-in to the device it is controlling.

The software written for embedded systems is often called firmware, and is

stored in read-only memory or flash convector chips rather than a disk drive. It often

runs with limited computer hardware resources: small or no keyboard, screen, and

little memory.

ROBOTICS

Robotics is the science and technology of robots, their design, manufacture,

and application. Robotics requires a working knowledge of electronics, mechanics

and software, and is usually accompanied by a large working knowledge of many

subjects. A person working in the field is a robotics.

Although the appearance and capabilities of robots vary vastly, all robots share

the features of a mechanical, movable structure under some form of autonomous

control. The structure of a robot is usually mostly mechanical and can be called a

kinematic chain (its functionality being akin to the skeleton of the human body). The

chain is formed of links (its bones), actuators (its muscles) and joints which can allow

one or more degrees of freedom. Most contemporary robots use open serial chains in

which each link connects the one before to the one after it. These robots are called

serial robots and often resemble the human arm. Some robots, such as the Stewart

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platform, use closed parallel kinematic chains. Other structures, such as those that

mimic the mechanical structure of humans, various animals and insects, are

comparatively rare. However, the development and use of such structures in robots is

an active area of research (e.g. biomechanics). Robots used as manipulators have an

end effector mounted on the last link. This end effector can be anything from a

welding device to a mechanical hand used to manipulate the environment.

A re-programmable, multifunctional manipulator designed to move material,

parts, tools, or specialized devices through various programmed motions for the

performance of a variety of tasks.

BLOCK DIAGRAM:

BLOCK DIAGRAM EXPLANATION:

In this section we will be discussing about the complete block diagram and

functional description of it.

Power supply:

5

MICRO CONTROLLER

UNIT

Land Mine Sensor

BUZZER

Battery

Motors

Drivers


In this system we are using 5V power supply for microcontroller of both

Transmitter section as well as receiver section. We use rectifiers for converting the

A.C. into D.C and a step down transformer to step down the voltage. The full

description of the Power supply section is given in this documentation in the

following sections i.e. hardware components.

Microcontroller (8051):

In this project the microcontroller plays a major role in transmitting data to RF

transmitter and here the data is transmitted using RF communication. In transmitter

side microcontroller directs the data obtained from PC and at the receiver side

microcontroller receives the data from the RF receiver and is given to robot.

H-Bridge:

Each H-Bridge having two inputs. Micro controller gives input to H-Bridge to control

the direction of the robot. Based on the given inputs to the H-Bridge, the motor will

be rotates either in clock-wise or in anti-clock wise direction. So that the movement of

the robot will be controlled

Land mine sensor:

Land mine sensor block is used to find landmines located in the path of the robot. It

will search for landmine and if it finds, it gives logic high to microcontroller. Metal

detector is used for this purpose.

Buzzer:

Buzzer in generally used to alert the humans by giving sound. In this project, if the

robot detects any landmine in the path, it will give the buzzer.

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SCHEMATIC:

SCHEMATIC EXPLANATION:

Power supply:

The main aim of this power supply is to convert the 230V AC into 5V DC in

order to give supply for the TTL or CMOS devices. In this process we are using a step

down transformer, a bridge rectifier, a smoothing circuit and the RPS.

At the primary of the transformer we are giving the 230V AC supply. The

secondary is connected to the opposite terminals of the Bridge rectifier as the input.

From other set of opposite terminals we are taking the output to the rectifier.

The bridge rectifier converts the AC coming from the secondary of the

transformer into pulsating DC. The output of this rectifier is further given to the

smoother circuit which is capacitor in our project. The smoothing circuit eliminates

the ripples from the pulsating DC and gives the pure DC to the RPS to get a constant

output DC voltage. The RPS regulates the voltage as per our requirement.

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Microcontroller:

The microcontroller AT89S51 with Pull up resistors at Port0 and crystal

oscillator of 11.0592 MHz crystal in conjunction with couple of capacitors of is

placed at 18th & 19th pins of 89S51 to make it work (execute) properly

H – Bridge motor:

This module is output to the microcontroller. The circuit for this motor is

designed in hybrid model with 4 transistors. And its two input pins are connected to

the pin1 and pin2(port 1.0 and 1.1) of the microcontroller. In this we are using two

motors. The other motor pins are connected to the pin3 and pin4(port 1.2 and 1.3) of

the microcontroller.

And the supply connections to these motors are given from the Power supply

output 7805 to the VCC and VSS pins.

Land mine sensor:

Land mine sensor is an input device, It is connected to 24 pin(port 2.3).It comprises of

sensor to sense electromagnetic pulses, its output is connected to base of the transistor

in amplifier circuit. Sensed data is given to microcontroller to which it is connected

Buzzer:

Buzzer is an output device. It is connected to 39 th pin (port 0.0) of microcontroller.

Depending upon the sensor value given to microcontroller makes buzzer on or off.

8


HARDWARE DESCRIPTION

MICRO CONTROLLER (AT89S51)

IntroductionA Micro controller consists of a powerful CPU tightly coupled with memory,

various I/O interfaces such as serial port, parallel port timer or counter, interrupt controller, data acquisition interfaces-Analog to Digital converter, Digital to Analog converter, integrated on to a single silicon chip. If a system is developed with a microprocessor, the designer has to go for external memory such as RAM, ROM, EPROM and peripherals. But controller is provided all these facilities on a single chip. Development of a Micro controller reduces PCB size and cost of design.

One of the major differences between a Microprocessor and a Micro controller is that a controller often deals with bits not bytes as in the real world application. Intel has introduced a family of Micro controllers called the MCS-51.

Figure: micro controller

FEATURES:

• Compatible with MCS-51® Products

• 4K Bytes of In-System Programmable (ISP) Flash Memory

– Endurance: 1000 Write/Erase Cycles

• 4.0V to 5.5V Operating Range

• Fully Static Operation: 0 Hz to 33 MHz

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• Three-level Program Memory Lock

• 128 x 8-bit Internal RAM

• 32 Programmable I/O Lines

• Two 16-bit Timer/Counters

• Six Interrupt Sources

• Full Duplex UART Serial Channel

• Low-power Idle and Power-down Modes

DESCRIPTION:

The AT89S51 is a low-power, high-performance CMOS 8-bit microcontroller with 4K

bytes of in-system programmable Flash memory. The device is manufactured using Atmel’s

high-density nonvolatile memory technology and is compatible with the industry- standard

80C51 instruction set and pinout. The on-chip Flash allows the program memory to be

reprogrammed in-system or by a conventional nonvolatile memory programmer. By

combining a versatile 8-bit CPU with in-system programmable Flash on a monolithic chip,

the Atmel AT89S51 is a powerful microcontroller which provides a highly-flexible and

cost-effective solution to many embedded control applications.

BLOCK DIAGRAM:

Figure: Block diagram

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PIN DIAGRAM:

Figure: pin diagram of micro controller

PIN DESCRIPTION:

VCC - Supply voltage.

GND - Ground.

Port 0:

Port 0 is an 8-bit open drain bidirectional I/O port. As an output port, each pin can

sink eight TTL inputs. When 1s are written to port 0 pins, the pins can be used as high-

impedance inputs. Port 0 can also be configured to be the multiplexed low-order

address/data bus during accesses to external program and data memory. In this mode, P0

has internal pull-ups. Port 0 also receives the code bytes during Flash programming and

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outputs the code bytes during program verification. External pull-ups are required

during program verification.

Port 1:

Port 1 is an 8-bit bidirectional I/O port with internal pull-ups. The Port 1 output

buffers can sink/source four TTL inputs. When 1s are written to Port 1 pins, they are pulled

high by the internal pull-ups and can be used as inputs. As inputs, Port 1 pins that are

externally being pulled low will source current (IIL) because of the internal pull-ups. Port 1

also receives the low-order address bytes during Flash programming and verification.

Port 2:




externally being pulled low will source current (IIL) because of the internal pull-ups. Port 2

also receives the high-order address bits and some control signals during Flash

programming and verification.

Port 3:




externally being pulled low will source current (IIL) because of the pull-ups. Port 3

receives some control signals for Flash programming and verification. Port 3 also serves the

functions of various special features of the AT89S51, as shown in the following table.

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RST:

Reset input. A high on this pin for two machine cycles while the oscillator is

running resets the device. This pin drives High for 98 oscillator periods after the Watchdog

times out. The DISRTO bit in SFR AUXR (address 8EH) can be used to disable this

feature. In the default state of bit DISRTO, the RESET HIGH out feature is enabled.

ALE/PROG:

Address Latch Enable (ALE) is an output pulse for latching the low byte of the

address during accesses to external memory. This pin is also the program pulse input

(PROG) during Flash programming. In normal operation, ALE is emitted at a constant rate

of 1/6 the oscillator frequency and may be used for external timing or clocking purposes.

Note, however, that one ALE pulse is skipped during each access to external data memory.

If desired, ALE operation can be disabled by setting bit 0 of SFR location 8EH. With the bit

set, ALE is active only during a MOVX or MOVC instruction. Otherwise, the pin is weakly

pulled high. Setting the ALE-disable bit has no effect if the microcontroller is in external

execution mode.

PSEN:

Program Store Enable (PSEN) is the read strobe to external program memory. When

the AT89S51 is executing code from external program memory, PSEN is activated twice

each machine cycle, except that two PSEN activations are skipped during each access to

external data memory.

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EA/VPP:

External Access Enable. EA must be strapped to GND in order to enable the device

to fetch code from external program memory locations starting at 0000H up to FFFFH.

Note, however, that if lock bit 1 is programmed, EA will be internally latched on reset. EA

should be strapped to VCC for internal program executions. This pin also receives the 12-

volt programming enable voltage (VPP) during Flash programming.

XTAL1:

Input to the inverting oscillator amplifier and input to the internal clock operating

circuit.

XTAL2:

Output from the inverting oscillator amplifier.

Oscillator Characteristics:

XTAL1 and XTAL2 are the input and output, respectively, of an inverting

amplifier which can be configured for use as an on-chip oscillator, as shown in Figs

6.2.3. Either a quartz crystal or ceramic resonator may be used. To drive the device

from an external clock source, XTAL2 should be left unconnected while XTAL1 is

driven as shown in Figure 6.2.4.There are no requirements on the duty cycle of the

external clock signal, since the input to the internal clocking circuitry is through a

divide-by-two flip-flop, but minimum and maximum voltage high and low time

specifications must be observed.

Fig 6.2.3 Oscillator Connections Fig 6.2.4 External Clock Drive Configuration

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POWER SUPPLY:

There are many types of power supply. Most are designed to convert high

voltage AC mains electricity to a suitable low voltage supply for electronics circuits

and other devices. A power supply can by broken down into a series of blocks, each

of which performs a particular function.

For example a 5V regulated supply:

Description

A variable regulated power supply, also called a variable bench power supply,

is one where you can continuously adjust the output voltage to your requirements.

Varying the output of the power supply is the recommended way to test a project after

having double checked parts placement against circuit drawings and the parts

placement guide.

This type of regulation is ideal for having a simple variable bench power supply.

Actually this is quite important because one of the first projects a hobbyist should

undertake is the construction of a variable regulated power supply. While a dedicated

supply

TRANSFORMER:

Transformers convert AC electricity from one voltage to another with little

loss of power. Transformers work only with AC and this is one of the reasons why

mains electricity is AC. Step-up transformers increase voltage, step-down

transformers reduce voltage. Most power supplies use a step-down transformer to

reduce the dangerously high mains voltage to a safer low voltage. The input coil is

15


called the primary and the output coil is called the secondary. There is no electrical

connection between the two coils, instead they are linked by an alternating magnetic

field created in the soft-iron core of the transformer. The two lines in the middle of the

circuit symbol represent the core. Transformers waste very little power so the power

out is (almost) equal to the power in. Note that as voltage is stepped down current is

stepped up. The ratio of the number of turns on each coil, called the turns ratio,

determines the ratio of the voltages. A step-down transformer has a large number of

turns on its primary (input) coil which is connected to the high voltage mains supply,

and a small number of turns on its secondary (output) coil to give a low output

voltage.

Fig 6.1.2 An Electrical Transformer

Turns ratio = Vp/VS = Np/NS

Power Out= Power In

VS X IS=VP X IP

Vp = primary (input) voltage

Np = number of turns on primary coil

Ip = primary (input) current

Full wave rectifier

Full wave rectifier circuit is shown in fig2(a). The transformer

secondary has a centre-tap and each half give voltage of Vm. In each half there is one

diode i.e. D1 and D2.the load resistance Rl is common to both halves. This can be

seen to comprise of two half-wave circuits. On the positive half cycle, when the point

is positive w.r.t point B, the Diode D1 conducts and current i1 flows through Rl .

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During this half cycle, the point C is negative w.r.t point B and hence the diode D2

does not conduct. Therefore i2=0.

On the negative half cycle the point C is positive w.r.t. point B. hence the diode

D2 conducts and current i2 flows through RL. During this half cycle. The point A is

negative w.r.t point B and hence the diode D1 does not conduct. Therefore i1=0

Fig2(b) and Fig2(c) shows the waveforms of currents i1 and i2. Since both i1

and i2 flow through the load RL, the current i through RL is i= i1+i2, which is

obtained by adding the two waveform and is shown in Fig2(d)

Advantages and disadvantages of full wave Rectifier:

(a) amount of ripple is much lower(r=0.482)as compared to half wave (r=1.21).

(b) Rectification efficiency is high (n=0.812)

(c) T.U.F is better (= 0.693) then that of half wave (=0.287).

(d) No problem of core saturation.

(e) Requires centre-tapped secondary of the transform

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A

B

C

Vm

Vm

Ac supply

D1

D2

RLE

i1

i2Fig2 (a) Full wave rectifier circuit


Comparison of rectifier circuits:

Parameter Type of Rectifier

Half wave full wave bridgeNumber of diodes

1 2

3

PIV of diodes Vm

2Vm

Vm

Secondary voltage (rms)

V

V-0-V

V

Secondary voltage Vm

V-0-V

Vm

D.C output voltage Vm/

2Vm/

2Vm/

Vdc,at no-load

0.318Vm

0.636Vm 0.636Vm

Ripple factor 1.21

0.482

0.482

Ripple frequency

f

2f

2f

Rectification efficiency

0.406

0.812

0.812

Transformer Utilization Factor(TUF)

0.287 0.693 0.812

Capacitor Filter:

We have seen that the ripple content in the rectified output of half wave

rectifier is 121% or that of full-wave or bridge rectifier or bridge rectifier is 48%

such high percentages of ripples is not acceptable for most of the applications. Ripples

can be removed by one of the following methods of filtering:

(a) A capacitor, in parallel to the load, provides a easier by –pass for the ripples

voltage though it due to low impedance

At ripple frequency and leave the d.c.to appears the load.

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(b) An inductor, in series with the load, prevents the passage of the ripple current (due

to high impedance at ripple frequency) while allowing the d.c (due to low resistance

to d.c)

(c) Various combinations of capacitor and inductor, such as L-section filter

section filter, multiple section filter etc. which make use of both the properties

mentioned in (a) and (b) Above.

Two cases of capacitor filter, one applied on half wave rectifier and another with full wave rectifier.

Full-wave Rectifier with capacitor filter:

Fig 4(a) shows the circuit diagram, with a full wave rectifier comprising of a center-

tapped secondary winding and two diodes. All the analysis given in this section are

also valid for a bridge rectifier, which also gives full-wave rectification. The filter

capacitor C is connected in parallel with load resistance RL.

In a manner similar to half-wave circuit with capacitor filter, in this circuit also the

capacitor C will get charged during short periods and thereafter, discharge through the

load resistance RL. One notable difference here is that the discharge duration is

shorter, whereas in half-wave case the duration was longer due to the missing half –

waves in between. As a result, the average value of output voltage is higher.

Bridge Rectifier A bridge rectifier makes use of four diodes in a bridge arrangement

to achieve full-wave rectification. This is a widely used configuration, both with

individual diodes wired as shown and with single component bridges where the diode

bridge is wired internally.

A bridge rectifier makes use of four diodes in a bridge arrangement to achieve

full-wave rectification. This is a widely used configuration, both with individual

19


diodes wired as shown and with single component bridges where the diode bridge is

wired internally.

Fig 6.1.3 A Typical Bridge Rectifier Circuit

Current Flow in the Bridge Rectifier

Fig 6.1.4 Current Flow in the Bridge Rectifier

For both positive and negative swings of the transformer, there is a forward

path through the diode bridge. Both conduction paths cause current to flow in the

same direction through the load resistor, accomplishing full-wave rectification. While

one set of diodes is forward biased, the other set is reverse biased and effectively

eliminated from the circuit.

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Fig 6.1.5 Current Flow in the Bridge Rectifier

Smoothing:

Smoothing is performed by a large value electrolytic capacitor connected

across the DC supply to act as a reservoir, supplying current to the output when the

varying DC voltage from the rectifier is falling. The diagram shows the unsmoothed

varying DC (dotted line) and the smoothed DC (solid line). The capacitor charges

quickly near the peak of the varying DC, and then discharges as it supplies current to

the output. Smoothing significantly increases the average DC voltage to almost the

peak value (1.4 × RMS value). For example 6V RMS AC is rectified to full wave DC

of about 4.6V RMS (1.4V is lost in the bridge rectifier), with smoothing this increases

to almost the peak value giving 1.4 × 4.6 = 6.4V smooth DC. Smoothing is not

perfect due to the capacitor voltage falling a little as it discharges, giving a small

ripple voltage. For many circuits a ripple, which is 10% of the supply voltage, is

satisfactory and the equation below gives the required value for the smoothing

capacitor. A larger capacitor will give less ripple. The capacitor value must be

doubled when smoothing half-wave DC.

Regulator:

Most digital logic circuits and processors need a 5-volt power supply. To use these

parts we need to build a regulated 5-volt source. Usually you start with an unregulated

power supply ranging from 9 volts to 24 volts DC (A 12 volt power supply is included

21


with the beginner kit and the Microcontroller. To make a 5 volt power supply, we use

a LM7805 voltage regulator IC (Integrated Circuit). The IC is shown below.

FIG 7.1

The LM7805 is simple to use. You simply connect the positive lead of your

unregulated DC power supply (anything from 9VDC to 24VDC) to the Input pin,

connect the negative lead to the Common pin and then when you turn on the power,

you get a 5 volt supply from the Output pin.

Circuit features

Brief description of operation: Gives out well regulated +5V output, output

current capability of 100 mA

Circuit protection: Built-in overheating protection shuts down output when regulator

IC gets too hot

Circuit complexity: Very simple and easy to build

Circuit performance: Very stable +5V output voltage, reliable operation

Availability of components: Easy to get, uses only very common basic components

Design testing: Based on datasheet example circuit, I have used this circuit

successfully as part of many electronics projects

Applications: Part of electronics devices, small laboratory power supply

Power supply voltage: Unregulated DC 8-18V power supply

Power supply current: Needed output current + 5 mA

Component costs: Few dollars for the electronics components + the input transformer

cost.

22

http://www.iguanalabs.com/1stled.htm


Voltage regulator ICs is available with fixed (typically 5, 12 and

15V) or variable output voltages. The maximum current they can pass also rates them.

Negative voltage regulators are available, mainly for use in dual supplies. Most

regulators include some automatic protection from excessive current ('overload

protection') and overheating ('thermal protection'). Many of the fixed voltage

regulator ICs have 3 leads and look like power transistors, such as the 7805 +5V 1A

regulator shown on the right.

Fig 6.1.6 A Three Terminal Voltage Regulator

LM787777777777XX7898

78XX:

The Bay Linear LM78XX is integrated linear positive regulator with three

terminals. The LM78XX offer several fixed output voltages making them useful in

wide range of applications. When used as a zener diode/resistor combination

replacement, the LM78XX usually results in an effective output impedance

improvement of two orders of magnitude, lower quiescent current.

The LM78XX is available in the TO-252, TO-220 & TO-263packages,

Features:

• Output Current of 1.5A

• Output Voltage Tolerance of 5%

• Internal thermal overload protection

• Internal Short-Circuit Limited

• No External Component

• Output Voltage 5.0V, 6V, 8V, 9V, 10V,12V, 15V, 18V, 24V

• Offer in plastic TO-252, TO-220 & TO-263

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• Direct Replacement for LM78XX

Applications:

• Post regulator for switching DC/DC converter

• Bias supply for analog circuits

DC Motor

DC motors are configured in many types and sizes, including brush

less, servo, and gear motor types. A motor consists of a rotor and a permanent

magnetic field stator. The magnetic field is maintained using either permanent

magnets or electromagnetic windings. DC motors are most commonly used in

variable speed and torque.

Motion and controls cover a wide range of components that in some

way are used to generate and/or control motion. Areas within this category include

bearings and bushings, clutches and brakes, controls and drives, drive components,

encoders and resolves, Integrated motion control, limit switches, linear actuators,

linear and rotary motion components, linear position sensing, motors (both AC and

DC motors), orientation position sensing, pneumatics and pneumatic components,

positioning stages, slides and guides, power transmission (mechanical), seals, slip

rings, solenoids, springs.

Motors are the devices that provide the actual speed and torque in a

drive system. This family includes AC motor types (single and multiphase motors,

universal, servo motors, induction, synchronous, and gear motor) and DC motors

(brush less, servo motor, and gear motor) as well as linear, stepper and air motors, and

motor contactors and starters.

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http://dc-motors.globalspec.com/Industrial-Directory/motor

http://dc-motors.globalspec.com/Industrial-Directory/motors













In any electric motor, operation is based on simple electromagnetism.

A current-carrying conductor generates a magnetic field; when this is then placed in

an external magnetic field, it will experience a force proportional to the current in the

conductor, and to the strength of the external magnetic field. As you are well aware of

from playing with magnets as a kid, opposite (North and South) polarities attract,

while like polarities (North and North, South and South) repel. The internal

configuration of a DC motor is designed to harness the magnetic interaction between a

current-carrying conductor and an external magnetic field to generate rotational

motion.

Let's start by looking at a simple 2-pole DC electric motor (here red

represents a magnet or winding with a "North" polarization, while green represents a

magnet or winding with a "South" polarization).

Every DC motor has six basic parts -- axle, rotor (a.k.a., armature), stator,

commutator, field magnet(s), and brushes. In most common DC motors (and all that

Beamers will see), the external magnetic field is produced by high-strength permanent

magnets1. The stator is the stationary part of the motor -- this includes the motor

casing, as well as two or more permanent magnet pole pieces. The rotor (together with

the axle and attached commutator) rotates with respect to the stator. The rotor consists

of windings (generally on a core), the windings being electrically connected to the

commutator. The above diagram shows a common motor layout -- with the rotor

inside the stator (field) magnets.

The geometry of the brushes, commutator contacts, and rotor windings are

such that when power is applied, the polarities of the energized winding and the stator

magnet(s) are misaligned, and the rotor will rotate until it is almost aligned with the

stator's field magnets. As the rotor reaches alignment, the brushes move to the next

25

http://encyclobeamia.solarbotics.net/articles/dc.html


http://encyclobeamia.solarbotics.net/articles/current.html





commutator contacts, and energize the next winding. Given our example two-pole

motor, the rotation reverses the direction of current through the rotor winding, leading

to a "flip" of the rotor's magnetic field, and driving it to continue rotating.

In real life, though, DC motors will always have more than two poles

(three is a very common number). In particular, this avoids "dead spots" in the

commutator. You can imagine how with our example two-pole motor, if the rotor is

exactly at the middle of its rotation (perfectly aligned with the field magnets), it will

get "stuck" there. Meanwhile, with a two-pole motor, there is a moment where the

commutator shorts out the power supply (i.e., both brushes touch both commutator

contacts simultaneously). This would be bad for the power supply, waste energy, and

damage motor components as well. Yet another disadvantage of such a simple motor

is that it would exhibit a high amount of torque” ripple" (the amount of torque it could

produce is cyclic with the position of the rotor).

So since most small DC motors are of a three-pole design, let's tinker with

the workings of one via an interactive animation (JavaScript required):

You'll notice a few things from this -- namely, one pole is fully energized

at a time (but two others are "partially" energized). As each brush transitions from one

commutator contact to the next, one coil's field will rapidly collapse, as the next coil's

field will rapidly charge up (this occurs within a few microsecond). We'll see more

26



about the effects of this later, but in the meantime you can see that this is a direct

result of the coil windings' series wiring:

There's probably no better way to see how an average dc motor is put together,

than by just opening one up. Unfortunately this is tedious work, as well as requiring

the destruction of a perfectly good motor. This is a basic 3-pole dc motor, with 2

brushes and three commutator contacts.

Land mine sensor or proximity sensor:

A proximity sensor detects an object when the object

approaches within the detection boundary of the sensor. Proximity sensors are used in

various facets of manufacturing for detecting the approach of metal objects. Various

types of proximity sensors are used for detecting the presence or absence of an object.

The design of a proximity sensor can be based on a number of principles of operation,

some examples include: variable reluctance, eddy current loss, saturated core, and

Hall Effect. Depending on the principle of operation, each type of sensor will have

different performance levels for sensing different types of objects. Common types of

non-contact proximity sensors include inductive proximity sensors, capacitive

proximity sensors, ultrasonic proximity sensors, and photoelectric sensors.

Hall-effect sensors detect a change in a polarity of a magnetic

field. Variable reluctance sensors typically include a U-type core and coils wound

around the core legs. Inductive proximity sensors have a lossy resonant circuit

(oscillator) at the input side whose loss resistance can be changed by the proximity of

an electrically conductive medium. An electrical capacitance proximity sensor

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converts a variation in electrostatic capacitance between a detecting electrode and a

ground electrode caused by approaching the nearby object into a variation in an

oscillation frequency, transforms or linearizes the oscillation frequency into a direct

current voltage, and compares the direct current voltage with a predetermined

threshold value to detect the nearby object.

Ultrasonic sensing systems provide a much more efficient and effective

method of longer range detection. These sensors require the use of a transducer to

produce ultrasonic signals. Eddy-current proximity sensors are well known and

operate on the principle that the impedance of an ac-excited electrical coil is subject to

change as the coil is brought in close proximity to a metallic object.

Proximity sensors often are employed in manufacturing industries in which the

sensors are exposed to harsh environmental conditions. Inductive proximity sensors

are used in automation engineering to define operating states in automating plants,

production systems and process engineering plants. Magnetic proximity detectors are

commonly used on ski lifts and tramways for detecting a drop condition of the steel

cable used as a haul line or haul rope.

Proximity sensors are widely used in the automotive industry to automate the

control of power accessories. For instance, proximity sensors are often used in power

window controllers to detect the presence of obstructions in the window frame when

the windowpane is being directed to the closed position.

CIRCUIT DESCRIPTION:

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In the project, our aim is to detect the land mines. So, to detect the land mines in the

path, we insert the land mine sensor. Land mine sensor will detect the electromagnetic

signals evolving from land mine. If it finds the land mine, it gives high pulse to

microcontroller. Microcontroller will understand that land mine is present at that place

and gives the high signal to buzzer in order to alert humans by sounding it.

Motors in the circuit are useful for the moment and directions of the robot., it

moves right by making left side motor off and running right side motor and vice

versa. This moment is to be programmed.

SOFTWARE Components

ABOUT SOFTWARE

Software used is:

*Keil software for C programming

*Express PCB for lay out design

*Express SCH for schematic design

KEIL µVision3

What's New in µVision3?

µVision3 adds many new features to the Editor like Text Templates, Quick

Function Navigation, and Syntax Coloring with brace high lighting Configuration

Wizard for dialog based startup and debugger setup. µVision3 is fully compatible to

µVision2 and can be used in parallel with µVision2.

What is µVision3?

µVision3 is an IDE (Integrated Development Environment) that helps you

write, compile, and debug embedded programs. It encapsulates the following

components:

A project manager.

A make facility.

Tool configuration.

Editor.

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A powerful debugger.

Express PCB

Express PCB is a Circuit Design Software and PCB manufacturing service.

One can learn almost everything you need to know about Express PCB from the help

topics included with the programs given.

Details:

Express PCB, Version 5.6.0

Express SCH

The Express SCH schematic design program is very easy to use. This software

enables the user to draw the Schematics with drag and drop options.

A Quick Start Guide is provided by which the user can learn how to use it.

Details:

Express SCH, Version 5.6.0

EMBEDDED C:

The programming Language used here in this project is an Embedded C

Language. This Embedded C Language is different from the generic C language in

few things like

a) Data types

b) Access over the architecture addresses.

The Embedded C Programming Language forms the user friendly language

with access over Port addresses, SFR Register addresses etc.

Embedded C Data types:

Data Types Size in Bits Data Range/Usage

unsigned char 8-bit 0-255

signed char 8-bit -128 to +127

unsigned int 16-bit 0 to 65535

signed int 16-bit -32,768 to +32,767

sbit 1-bit SFR bit addressable only

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bit 1-bit RAM bit addressable only

sfr 8-bit RAM addresses 80-FFH only

Signed char:

o Used to represent the – or + values.

o As a result, we have only 7 bits for the magnitude of the signed number,

giving us values from -128 to +127.

CIRCUIT DESCRIPTION:

This project is basically aimed to build a system in which the controlling of

robot is done based on the instructions given at PC and.There are two sections in this

project one is transmitter section which contain PC, microcontroller , RF encoder and

RF Transmitter and receiver section contain RF Decoder ,RF receiver, micro

controller and Robot.

Transmitter section:

In transmitter section, PC is used for entering the instructions to control robot.

Micro controller reads the instructions and directs the data to receiver by encoding

data and transmitting wirelessly using RF transmitter.

Receiving section:

In receiver section, the control signals are taken by RF receiver from

transmitter section. These control signals are read by micro controller and controls the

robot based on the RF signals received.

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SOFTWARE µVision3

µVision3 is an IDE (Integrated Development Environment) that helps you write,

compile, and debug embedded programs. It encapsulates the following components:

A project manager.

A make facility.

Tool configuration.

Editor.

A powerful debugger.

To help you get started, several example programs (located in the \C51\Examples, \

C251\Examples, \C166\Examples, and \ARM\...\Examples) are provided.

HELLO is a simple program that prints the string "Hello World" using the

Serial Interface.

Building an Application in µVision2

To build (compile, assemble, and link) an application in µVision2, you must:

1. Select Project - (for example, 166\EXAMPLES\HELLO\HELLO.UV2).

2. Select Project - Rebuild all target files or Build target.

µVision2 compiles, assembles, and links the files in your project.

Creating Your Own Application in µVision2

To create a new project in µVision2, you must:

1. Select Project - New Project.

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2. Select a directory and enter the name of the project file.

3. Select Project - Select Device and select an 8051, 251, or C16x/ST10 device

from the Device Database™.

4. Create source files to add to the project.

5. Select Project - Targets, Groups, Files, Add/Files, select Source Group1, and

add the source files to the project.

6. Select Project - Options and set the tool options. Note when you select the

target device from the Device Database™ all special options are set

automatically. You typically only need to configure the memory map of your

target hardware. Default memory model settings are optimal for most

applications.

7. Select Project - Rebuild all target files or Build target.

Debugging an Application in µVision2

To debug an application created using µVision2, you must:

1. Select Debug - Start/Stop Debug Session.

2. Use the Step toolbar buttons to single-step through your program. You may

enter G, main in the Output Window to execute to the main C function.

3. Open the Serial Window using the Serial #1 button on the toolbar.

Debug your program using standard options like Step, Go, Break, and so on.

Starting µVision2 and creating a Project

µVision2 is a standard Windows application and started by clicking on the

program icon. To create a new project file select from the µVision2 menu

Project – New Project…. This opens a standard Windows dialog that asks you for the

new project file name.

We suggest that you use a separate folder for each project. You can simply use

the icon Create New Folder in this dialog to get a new empty folder. Then select this

folder and enter the file name for the new project, i.e. Project1.

µVision2 creates a new project file with the name PROJECT1.UV2 which

contains a default target and file group name. You can see these names in the Project

Window – Files.

Now use from the menu Project – Select Device for Target and select a CPU

for your project. The Select Device dialog box shows the µVision2 device database.

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Just select the microcontroller you use. We are using for our examples the Philips

80C51RD+ CPU. This selection sets necessary tool options for the 80C51RD+ device

and simplifies in this way the tool Configuration

Building Projects and Creating a HEX Files

Typical, the tool settings under Options – Target are all you need to start a

new application. You may translate all source files and line the application with a

click on the Build Target toolbar icon. When you build an application with syntax

errors, µVision2 will display errors and warning messages in the Output

Window – Build page. A double click on a message line opens the source file on the

correct location in a µVision2 editor window.

Once you have successfully generated your application you can start debugging.

After you have tested your application, it is required to create an Intel HEX

file to download the software into an EPROM programmer or simulator. µVision2

creates HEX files with each build process when Create HEX files under Options for

Target – Output is enabled. You may start your PROM programming utility after the

make process when you specify the program under the option Run User Program #1.

CPU Simulation

µVision2 simulates up to 16 Mbytes of memory from which areas can be

mapped for read, write, or code execution access. The µVision2 simulator traps and

reports illegal memory accesses being done.

In addition to memory mapping, the simulator also provides support for the integrated

peripherals of the various 8051 derivatives. The on-chip peripherals of the CPU you

have selected are configured from the Device

Database selection

You have made when you create your project target. Refer to page 58 for more

Information about selecting a device. You may select and display the on-chip

peripheral components using the Debug menu. You can also change the aspects of

each peripheral using the controls in the dialog boxes.

Start Debugging

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You start the debug mode of µVision2 with the Debug – Start/Stop Debug

Session command. Depending on the Options for Target – Debug Configuration,

µVision2 will load the application program and run the startup code µVision2 saves

the editor screen layout and restores the screen layout of the last debug session. If the

program execution stops, µVision2 opens an editor window with the source text or

shows CPU instructions in the disassembly window. The next executable statement is

marked with a yellow arrow. During debugging, most editor features are still

available.

For example, you can use the find command or correct program errors.

Program source text of your application is shown in the same windows. The µVision2

debug mode differs from the edit mode in the following aspects:

_ The “Debug Menu and Debug Commands” described on page 28 are Available. The

additional debug windows are discussed in the following.

_ The project structure or tool parameters cannot be modified. All build Commands

are disabled.

Disassembly Window

The Disassembly window shows your target program as mixed source and

assembly program or just assembly code. A trace history of previously executed

instructions may be displayed with Debug – View Trace Records. To enable the trace

history, set Debug – Enable/Disable Trace Recording.

If you select the Disassembly Window as the active window all program step

commands work on CPU instruction level rather than program source lines. You can

select a text line and set or modify code breakpoints using toolbar buttons or the

context menu commands.

You may use the dialog Debug – Inline Assembly… to modify the CPU

instructions. That allows you to correct mistakes or to make temporary changes to the

target program you are debugging.

SOURCE CODE:

1. Click on the Keil uVision Icon on Desktop

2. The following window will appear

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3. Click on the Project menu from the title bar

4. Then Click on New Project

5. Save the Project by typing suitable project name with no extension in your own folder sited in either C:\ or D:\

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6. Then Click on save button above.

7. Select the component for your project. i.e. Atmel……

8. Click on the + Symbol beside Atmel

9. Select AT89C51 as shown below

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10. Then Click on “OK”

11. The Following window will appear

12. Then Click either YES or NO………mostly “NO”

13. Now your project is ready to USE

14. Now double click on the Target1, you would get another option “Source

group 1” as shown in next page.

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15. Click on the file option from menu bar and select “new”

16. The next screen will be as shown in next page, and just maximize it by

double clicking on its blue boarder.

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17. Now start writing program in either in “C” or “ASM”

18. For a program written in Assembly, then save it with extension “. asm”

and for “C” based program save it with extension “ .C”

19. Now right click on Source group 1 and click on “Add files to Group Source”

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20. Now you will get another window, on which by default “C” files will appear.

21. Now select as per your file extension given while saving the file

22. Click only one time on option “ADD”

23. Now Press function key F7 to compile. Any error will appear if so happen.

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24. If the file contains no error, then press Control+F5 simultaneously.

25. The new window is as follows

26. Then Click “OK”

27. Now Click on the Peripherals from menu bar, and check your required port

as shown in fig below

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28. Drag the port a side and click in the program file.

29. Now keep Pressing function key “F11” slowly and observe.

30. You are running your program successfully

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CONCLUSION

The project “LAND MINE DETECTING ROBOT” has been successfully

designed and tested. Integrating features of all the hardware components used have

developed. Presence of every module has been reasoned out and placed carefully thus

contributing to the best working of the unit.

Secondly, using highly advanced IC’s and with the help of growing

technology the project has been successfully implemented.

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FUTURE ASPECTS

In this project, the robot is connected with land mine detector and is self

controlled and it will sound the buzzer when it finds the landmine. This project can be

extended by making robot controlled by human; it can be by mobile i.e., GSM

technology, or PC. And also can try to make the landmine disposed by robot using

advanced technologies.

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BIBLIOGRAPHY

NAME OF THE SITES

1. WWW.MITEL.DATABOOK.COM

2. WWW.ATMEL.DATABOOK.COM

3. WWW.FRANKLIN.COM

4. WWW.KEIL.COM

REFERENCES

1. 8051-MICROCONTROLLER AND EMBEDDED SYSTEM.

Mohd. Mazidi.

2. The 8051 Micro controller Architecture, Programming & Applications

-Kenneth J.Ayala

3. Micro processor Architecture, Programming & Applications

-Ramesh S.Gaonkar

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http://WWW.KEIL.COM/

http://WWW.FRANKLIN.COM/

http://WWW.ATMEL.DATABOOK.COM/

http://WWW.MITEL.DATABOOK.COM/


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Date post:	23-Nov-2014
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