Download - Kapil Project
-
8/3/2019 Kapil Project
1/61
OBSTACLE DETECTOR AND AVOIDER WITH DTMF
CONTROL
A PROJECT
SUBMITTED IN FULFILMENT OF REQUIREMENTS FOR THE
INDUSTRIAL TRAINING
BACHELOR OF TECHNOLOGY
(ELECTRONICS AND COMMUNICATION)
BY
KAPIL RANA (0951312808)
UNDER THE GUIDANCE OF MR. PRAVEEN
TO
DEPARTMENT OF ELECTRONICS AND COMMUNICATION
GURU PREMSUKH MEMORIAL COLLEGE OF ENGINEERING
BUDHPUR, DELHI-110036
AUGUST 2011
-
8/3/2019 Kapil Project
2/61
ACKNOWLEDGEMENT
The success of this project can be attributed to a number of people. Firstly
we would like to thank our Mr. PRAVEEN(PROJECT LEADER) for his
support and valuable technical advice during the course of the project.
I am thankful to our LAB supervisor who helped us a lot in the
implementation phase of our project.
A warm thanks goes to our family and friends who had provided support
during the challenges, and understanding of our many hours spending duringthe project.
KAPIL RANA (0951312808)
-
8/3/2019 Kapil Project
3/61
CERTIFICATE
It is certify that the project has been carried out by PANKAJ
CHOUDHARY a student of 4th semester under our guidance. The report
covers all the aspects of the work done ( including H/W & S/W, Coding etc.)
The project report is complete in all respects and I have understood the
entire software. It shall be possible for the next batch of the students to take
up further work after consulting this report.
(Signatures)/ Date
Mr. B.P ARUN
(DIRECTOR)
-
8/3/2019 Kapil Project
4/61
CONTENTS
1) INTRODUCTION
2) OBJECTIVE
3) METHODOLOGY
4) DETAILS - The Differential Steering System
- Mechanical and Structural Actuators
- DC Motor
- H- Bridge Motor Control
- Design and Implementation- Coding
5) LIMITATIONS
6) APPLICATIONS
7) RESULTS AND CONCLUSIONS
8) BIBLIOGRAPHY
-
8/3/2019 Kapil Project
5/61
INTRODUCTION
An Autonomous obstacle avoider is a robot which while its journey, avoids the
obstacles itself. Before striking any obstacle, it changes its direction. The basic
aim behind making the obstacle avoider is to apply the principle in the new
generation cars which moves in autopilot mode. New generation of automobiles
will use the technology for obstacle avoidance in a different manner, for instance
the sensor may be used to slow down the vehicle instead of changing direction of
motion or control the direction wirily or wirelessly (i.e. using DTMF). Many
industrial applications are there undone. This project also aims at giving a newdirection to autopilot modes of airplanes and helipads. For further clarifications of
project we need to understand some basic components and the basic principle as
well.
The word "robot" originates from the Czech word for forced labor or serf. Robots
are electronic devices intended to perform a desired function. Many refer to them
as "machines", however, a drill press is a machine, yet it requires an operator to
perform its function, where robots can be programmed to do it themselves. Robots
have the potential to change our economy, our health, our standard of living, our
knowledge and the world in which we live. As the technology progresses, we are
finding new ways to use robots. Each new use brings new hope and possibilities,
but also potential dangers and risks. Robotics is not only a science, but it is also
an art. The bots we build reflect the ideas and personalities we portray. There are
many different versions of robots that can be made. From turtle bots to vehicles
like the Mars rovers to rovers like R2-D2. From walkers that have anywhere from
1 to 10 legs to robotic arms to androids. Whatever you can dream, you can create.
-
8/3/2019 Kapil Project
6/61
The level of expertise you want your robot to have and how much learning and
research you want to do is up to you. We have seen how ants always travel in a
line, following an invisible route in search of food, or back home. How on roads
we follow lanes to avoid accidents and traffic jams. Ever thought about a robot
which follows line? A perfect or near perfect mimic of mother-nature?
In the age of ubiquitous systems it is important to be able to control robots
everywhere. Although many methods to remotely control robots have been
devised, the methods have the problems such as the need for special devices or
software to control the robots. This paper suggests a method for robotic control
using the DTMF tone generated when the user pushes mobile phone keypad
buttons or when connected with a remote mobile robot.
Conventionally, Wireless-controlled robots use rf circuits, which have the
drawbacks of limited working range, limited frequency range and the limited
control. Use of a mobile phone for robotic control can overcome these limitations.
It provides the advantage of robust control, working range as large as the
coverage area of the service provider, no interference with other controllers andup to twelve controlles.
Although the appearance and the capabilities of robots vary vastly, all robots
share the feature of a mechanical, movable structure under some form of control.
The Control of robot involves three distinct phases: perception, processing and
action. Generally, the preceptors are sensors mounted on the robot, processing is
done by the on-board microcontroller or processor, and the task is performed
using motors or with some other actuators.
-
8/3/2019 Kapil Project
7/61
OBJECTIVE
To build a car that will detect the object and hence avoid it follow the
instructions viz moving straight in backward, forward, rightward or leftward
directions or to stop, made by the controller via a Bluetooth enabled mobile
phone.
-
8/3/2019 Kapil Project
8/61
DETAILS
1) THE DIFFERENTIAL STEERING SYSTEM
(LOCOMOTION)
The differential steering system is familiar from ordinary life because it is the
arrangement used in a wheelchair. Two wheels mounted on a single axis are
independently powered and controlled, thus providing both drive and steering.
Additional passive wheels (usually casters) are provided for support. Most of us
have an intuitive grasp of the basic behavior of a differential steering system. If
both drive wheels turn in tandem, the robot moves in a straight line. If one wheel
turns faster than the other, the robot follows a curved path. If the wheels turn at
equal speed, but in opposite directions, the robot pivots.For motion with turns, we
need at least three wheels
2 fixed, motor driven wheels
1 free motion caster wheel
1(a) Forward Motion
-
8/3/2019 Kapil Project
9/61
1(b) backward motion
1(c) Left turn
-
8/3/2019 Kapil Project
10/61
1(d) Right turn
Figure 1: The Differential steering model
-
8/3/2019 Kapil Project
11/61
2) MECHANICAL AND STRUCTURAL ACTUATORS-
MECHANICAL HARDWARE USED-
1. Caster - 1
2. Screw for Caster - 4
3. Hexagonal Nut for Caster - 4
4. Wheels - 2
STRUCTURAL ACTUATORS USED-
D C Geared motors (12 volts, 150 rpm) - 2
-
8/3/2019 Kapil Project
12/61
CASTER
The picture of caster wheel is shown below..
A caster (or castor) is an un-driven, single, double, or compound wheel mounted
on an object to make movement easier. Found on shopping carts , office chairs
-
8/3/2019 Kapil Project
13/61
and material handling equipment, casters may be fixed to roll in one direction, or
mounted on a pivot, such that the wheel will automatically swivel, aligning itself
to the direction in which it is moving. Swivelling casters are sometimes
themselves attached to handles, so users can turn the caster into the desired
direction.
Casters are used in many industrial applications. Heavy duty and high capacity
casters are used on platform trucks, carts, assemblies, and tow lines in plants.
DESIGNS AND APPLICATIONS
A caster is defined as a wheel mounted to a fork, but has an additional offset
steering joint. The steering joint allows the wheel to rotate freely in 360. This
allows for easy turning of objects without changing the direction of the chassis
that the casters are mounted to. The angle and distance of the wheel axles and
steering joint can be adjusted for different types of caster performance.
Casters are typically used on carts and furniture and are mounted underneath these
platforms. Casters are advantageous for moving vehicles or platforms in both
straight and turning motions. Casters are commonly used on supermarket
shopping cart.
During straightforward motion, the swivel caster will tend to rotate parallel to the
direction of travel. This can be seen on a shopping cart when the caster rotates
backwards during forward motion down an aisle. A benefit of this caster rotation
is the vehicle naturally tends to travel in a straight direction. Precise steering is
not required because the casters tend to maintain straight motion.
This is also true during turning. The caster rotates again parallel to the turning
radius and provides a smooth turn. The can be seen on a shopping cart as the
-
8/3/2019 Kapil Project
14/61
wheels rotate differently depending on how tight a turn is made. Because of these
two qualities, casters are often used on dollies, office chairs, and wheelchairs.
Casters can be designed in many different sizes and materials depending on
application. Generally, they are made from rubber, plastic, nylon, aluminum, or
stainless steel. Generally, casters operate well on smooth and flat surfaces.
WHEELS:
The wheels connected to geared motors are shown below.
The basic purpose of wheels connected to geared motors is to convert the
rotational torque of shaft (which moves due to the rotation of gears), to linear
motion for the car. Positioning and alignment of wheels is necessary for the
smooth motion of car.
-
8/3/2019 Kapil Project
15/61
Also, they are to be fixed on the shaft in such a manner that they rotate only on
the movement of shaft and unlike caster are not free to rotate as such.
Wheels are the most important part for any car for its linear motion and so
knowledge about their proper use is necessary for any person related to the field.
GEAR MECHANISM IN MOTORS-
A gear is a component within a transmission device that transmits rotational
torque by applying a force to the teeth of another gear or device. A gear is
different from a pulley in that a gear is a round wheel that has linkages ("teeth" or
"cogs") that mesh with other gear teeth, allowing force to be fully transferred
without slippage. Depending on their construction and arrangement, geared
devices can transmit forces at different speeds, torques, or in a different direction,
from the power source. The most common situation is for a gear to mesh with
another gear, but a gear can mesh with any device having compatible teeth, such
as linear moving racks.
The gear's most important feature is that gears of unequal sizes (diameters) can be
combined to produce a mechanical advantage, so that the rotational speed and
torque of the second gear are different from those of the first. In the context of a
particular machine, the term "gear" also refers to one particular arrangement of
gears among other arrangements (such as "first gear"). Such arrangements are
often given as a ratio, using the number of teeth or gear diameter as units.
-
8/3/2019 Kapil Project
16/61
(3)D.C. MOTORS
DC motors are widely used, inexpensive, small and powerful for their size.
Reduction gearboxes are often required to reduce the speed and increase the
torque output of the motor. Unfortunately more sophisticated control algorithms
are required to achieve accurate control over the axial rotation of these motors.
Although recent developments in stepper motor technologies have come a long
way, the benefits offered by smooth control and high levels of acceleration with
DC motors far outweigh any disadvantages.
Several characteristics are important when selecting DC motors and these can be
split into two specific categories. The first category is associated with the input
ratings of the motor and specifies its electrical requirements, like operating
voltage and current. The second category is related to the motor's output
characteristics and specifies the physical limitations of the motor in terms of
speed, torque and power.
Example specifications of the motors used are given below:
CHARACTERISTICS VALUE
Operating voltage - 6V to 12V
Operating current - 2A MAX.
Speed - 2400 rpm
Torque - 30 gm-cm
-
8/3/2019 Kapil Project
17/61
As noticed, the torque provided can hardly move 30gm of weight around with
wheel diameter of about 2cm. This is a fairly a huge drawback as the robot could
easily weigh about a kg. This is accomplished by gears which reduce the speed
(2400 rpm is highly impractical) and effectively increase the torque. If the speed
is reduced by using a gear system by a factor of then the torque is increased by
the same factor. For example, if the speed is reduced from 2400 rpm, to 30 rpm,
then the torque is increased by a factor of (2400/30 = 80) in other words the
torque becomes 30x80=2400 gm-cm or 2.4 kg-cm which is more than sufficient.
(4) H-BRIDGE MOTOR CONTROL
DC motors are generally bi-directional motors. That is, their direction of rotation
can be changed by just reversing the polarity. But once the motors are fixed,
control becomes tricky. This is done using the H-Bridge. The figure is given
below.
-
8/3/2019 Kapil Project
18/61
Figure 4: The H-Bridge Using Relays.
The Explanation is simple, If A & D are turned on, then the current flows in the
direction shown in the figure below.
Figure 4.1: Clockwise rotation
-
8/3/2019 Kapil Project
19/61
If B & C are turned on, then the motor rotates in counter clockwise direction.
Figure 4.2: Counter-Clockwise rotation
If you turn on the two upper circuits, the motor resists turning, so you effectively
have a breaking mechanism. The same is true if you turn on both of the lower
circuits. This is because the motor is a generator and when it turns it generates a
voltage. If the terminals of the motor are connected (shorted), then the voltage
generated counteracts the motors freedom to turn. It is as if you are applying a
similar but opposite voltage to the one generated by the motor being turned. In
other words, it acts like a brake. Any other state like A & C = ON or B & D = ON
will cause a direct path to ground causing a very high current to pass through the
relays thus causing a burnt fuse (if it exists).
-
8/3/2019 Kapil Project
20/61
The following figure shows an H-Bridge using only transistors. The same theory
applies
.
Figure 4.3: H-Bridge using transistors.
Usually, the above circuitry can be used only for direction control. The Existing
H-Bridge is further modified to include another transistor, now making speed
control possible too. This is shown in the figure below.
-
8/3/2019 Kapil Project
21/61
Figure 4.4: Enhanced H-Bridge
The same direction rules apply, but now the motor will behave as per the direction
control only when a 1 is given to the EN input. Speed control is usually done bygiving a PWM signal, and the duty cycle is varied to vary the speed of the motor.
Usually protection diodes are also incorporated across the transistors to catch the
back voltage that is generated by the motor's coil when the power is switched on
and off. This fly-back voltage can be many times higher than the supply voltage!
If diodes are not used, the transistors have a good chance to get burnt.
-
8/3/2019 Kapil Project
22/61
(5)DESIGN & IMPLEMENTATION
The block diagram of circuit is given below. It consists of mainly four parts:-
1. Microcontroller Unit
2. DTMF Unit
3. H-Bridge Circuit
4. IR Sensor
Figure 5: BLOCK DIAGRAM
Microcontroller
Unit
Module
DTMF
Unit
H-Bridge
Circuit
IRSensor
-
8/3/2019 Kapil Project
23/61
5.1 MICRO-
CONTROLLER UNIT MODULE
2
.
8
.
5
.
6.
-
8/3/2019 Kapil Project
24/61
1. Atmel AT89S52 Microcontroller chip - 1
2. Connection for Adapter - 1
3. Pins according to AT89S52 configuration - 40
4. Resistor(1 K) - 1
5. Diodes (1N4007) - 4
6. Electrolytic Capacitor(1000 F) - 1
7. Voltage Regulator 7805(5 V) - 1
8. Capacitor(10 F) - 2
7
.
4
.
9
.
3
.
1
0
1.
1
.
-
8/3/2019 Kapil Project
25/61
9. Crystal Oscillator(11.0592Mhz) - 1
10. 10 k sip - 1
5.1.1 AT89S52 MICROCONTROLLER:
(a)DESCRIPTION:
The AT89S52 is a low-power, high-performance CMOS 8-bit microcontroller
with 8K bytes of in-system programmable Flash memory. The device is
manufactured using Atmels high-density non-volatile memory technology and is
compatible with the industry-standard 80C51 instruction set and pin-out. The on-
chip Flash allows the program memory to be reprogrammed in-system or by a
conventional non-volatile memory programmer. By combining a versatile 8-bit
CPU with in-system programmable Flash on a monolithic chip, the Atmel
AT89S52 is a powerful microcontroller which provides a highly-flexible and cost-
effective solution to many embedded control applications. The AT89S52 provides
the following standard features: 8K bytes of Flash, 256 bytes of RAM, 32 I/O
lines, Watchdog timer, two data pointers, three 16-bit timer/counters, a six-vector
two-level interrupt architecture, a full duplex serial port, on-chip oscillator, and
clock circuitry. In addition, the AT89S52 is designed with static logic for
operation down to zero frequency and supports two software selectable power
saving modes. The Idle Mode stops the CPU while allowing the RAM,
timer/counters, serial port, and interrupt system to continue functioning. The
Power-down mode saves the RAM con-tents but freezes the oscillator, disabling
all other chip functions until the next interrupt or hardware reset.
-
8/3/2019 Kapil Project
26/61
(b)PIN CONFIGURATION:
123456
78910111213141516
17181920
403938373635
34333231302928272625
24232221
P1.0P1.1P1.2P1.3P1.4P1.5
P1.6P1.7RST
(RXD)P3.0(TXD)P3.1
(T0)P3.4(T1)P3.5
XTAL2XTAL1
GND
(INT0)P3.2
(INT1)P3.3
(RD)P3.7
(WR)P3.6
VccP0.0(AD0)P0.1(AD1)
P0.2(AD2)P0.3(AD3)P0.4(AD4)
P0.5(AD5)P0.6(AD6)P0.7(AD7)
EA/VPPALE/PROG
PSENP2.7(A15)
P2.6(A14)P2.5(A13)P2.4(A12)
P2.3(A11)P2.2(A10)P2.1(A9)P2.0(A8)
8051
(8031)
ATMEL
89S52
-
8/3/2019 Kapil Project
27/61
-
8/3/2019 Kapil Project
28/61
(d)PIN DESCRIPTION
1)VCC-Supply voltage.2) GND- Ground.
3) 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 outputs the code bytes during program
verification. External pull-ups are required during program verification.
4) 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. In addition, P1.0 and P1.1 can be configured to
be the timer/counter 2 external count input (P1.0/T2) and the timer/counter 2
trigger input (P1.1/T2EX), respectively, as shown in the following table. Port 1
also receives the low-order address bytes during Flash programming and
verification.
5) Port 2 - Port 2 is an 8-bit bidirectional I/O port with internal pull-ups. The Port
2 output buffers can sink/source four TTL inputs. When 1s are written to Port 2
pins, they are pulled high by the internal pull-ups and can be used as inputs. As
inputs, Port 2 pins that are externally being pulled low will source current (IIL)
because of the internal pull-ups. Port 2 emits the high-order address byte during
fetches from external program memory and during accesses to external data
-
8/3/2019 Kapil Project
29/61
memory that uses 16-bit addresses (MOVX @ DPTR). In this application, Port 2
uses strong internal pull-ups when emitting 1s. During accesses to external data
memory that uses 8-bit addresses (MOVX @ RI), Port 2 emits the contents of the
P2 Special Function Register. Port 2 also receives the high-order address bits and
some control signals during Flash programming and verification.
6) Port 3 - This does not need any pull-up resistors since it already has
Pull-up resistors internally. Although port 3 is configured as an output port upon
reset, this is not the way it is most commonly used.
Port 3 has the additional function of providing signals.This can be seen from thenext table.
PORT 3 Table of functions
7) 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
-
8/3/2019 Kapil Project
30/61
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.
8) 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.
9) PSEN - Program Store Enable (PSEN) is the read strobe to external program
memory. When the AT89S52 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.
10) 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.
11) XTAL1 - Input to the inverting oscillator amplifier and input to the internal
clock operating circuit.
12) XTAL2 - Output from the inverting oscillator amplifier.
-
8/3/2019 Kapil Project
31/61
5.1.2 FUNCTION OF OTHER PARTS:
1. CONSTANT VOLTAGE SUPPLY (POWER SUPPLY UNIT)7805
KA7805/KA7805A (3-Terminal 1A Positive Voltage Regulator)
As clear from its name, the function of voltage regulator 7805 is , basically to
regulate the voltage. By this, we mean to ensure a constant supply at a level of 5
volts compared to ground. This is essential as the Micro-controller works on
voltage levels 5V and ground.
Figure 5.1: A typical 7805 voltage regulator IC
Features
Output Current up to 1A.
Output Voltage of 5V.
Thermal Overload Protection.
Short Circuit Protection.
Output Transistor Safe Operating Area Protection.
Input voltage(Vi)
for Vo= 5 to 18 V - 35V
for Vo= 24 V - 40V
-
8/3/2019 Kapil Project
32/61
Operating Temperature up to ~ +125 degree Celcius
Description
The KA7805/KA7805A series of three-terminal positive regulator are available in
the TO-220/D-PAK package and with several fixed output voltages, making them
useful in a wide range of applications. Each type employs internal current
limiting, thermal shut down and safe operating area protection, making it
essentially indestructible. If adequate heat sinking is provided, they can deliver
over 1A output current. Although designed primarily as fixed voltage regulators,
these devices can be used with external components to obtain adjustable voltages
and currents.
Figure 5.2: Internal Block diagram of a 7805 voltage regulator IC
2. Capacitors (10 F)
The capacitor (10 F) connected at the left side is for reset of the circuit and the
one at the right side is to smoothen the output load.
-
8/3/2019 Kapil Project
33/61
3. Electrolytic Capacitors (1000 F) and Diodes
These form the bridge rectifier circuit for the micro-controller unit module. This
circuit is responsible for fact that the car will run on both ac and dc. In case of dc,
the rectifier circuit will not come into account but in case of ac, the circuit will
convert the ac into dc. This is essential as the micro-controller runs on dc.
4.10 k sip
This 10 k sip is a register network. Its function is to give active-low on Port P0.
So, what happens is that all the 8 pins of P0 have 5 volts on them and so are
disabled. Only when they are made 0 do the pins become enabled.
5. Crystal (11.0592 MHz)
This is a Quartz crystal. Its function is to provide for the pins XTAL1 and
XTAL2. The crystal provides for the internal operating clock and also is the input
to the inverting oscillating amplifiers in the internal structure of the AT89S52
micro-controller.
-
8/3/2019 Kapil Project
34/61
5.2 H-BRIDGE CIRCUIT
5.2.1 H-BRIDGE (Transistor Circuit)
As can be seen from the numbers listed on the diagram, the components are:
1. Opto-Couplers (PC 817) - 4
2. Resistors (1 K ) - 16
3. Transistors (BC 557) - 8
4. Transistors (NPN , TIP 112) - 4
5. Transistors (PNP , TIP 127) - 4
6. Connections with Motors - 2
7. Diodes (1N4007, 1 Ampere) - 8
3
.
5
4
1
5
2
6
7
-
8/3/2019 Kapil Project
35/61
FUNCTIONS OF INDIVIDUAL PARTS-
1. PC 817 OPTO-COUPLER-
Its function is isolation of the voltage levels of the DC motor and the micro-
controller. The micro-controller works on 5 volts but the DC motor works on 12
volts. As these two are different voltage levels, there is a need of isolation and the
four-legged PC 817 device is used here.
2. BC 557 TRANSISTORS-
The function of BC 557 transistors is to perform the EX-OR operation in the
module. This leads to the fact that the DC motor will work either on 10 or 01
logic levels coming from the micro-controller to the input signal position in the
H-Bridge module. So, the DC motor is saved from damage. This is because if 00
or 11 are supplied to the motors, they will be shorted as explained i the theory
about H-Bridges.
-
8/3/2019 Kapil Project
36/61
3. TIP 112 and TIP 127-There are 8 transistors connected in the H-Bridge
module other than BC 557. Of them, 4 are TIP 112 and 4 are TIP 127. The former
are NPN transistors and the latter are PNP transistors. They make up in total 4
Darlington Pairs.
A Darlington Pair is a circuit consisting of transistors which is responsible for
current amplification. Eventually, this current is supplied to the DC motors to
make them run.
4. Diodes-
There are 8 diodes used here. Their number is 1N4007 and of 1 ampere currentrating. They are used to prevent back e.m.f. This back e.m.f can cause damage to
the DC motor.
5.2.2 H-BRIDGE IC (L298)
The L298 is a Dual Full Bridge driver that can drive up to 2Amps per bridge with
supply voltage up to 46V. It can drive DC motors, stepper motors, relays,
solenoids, etc. The device is TTL compatible. Two H bridges of L298 can be
connected in parallel to increase its current capacity to 4 Amp. It can be used in
conjunction with stepper motor controller for driving one/two phase stepper
motor. The device is available in 15- lead Multi watt package.
-
8/3/2019 Kapil Project
37/61
PIN CONFIGURATION
APPLICATIONS
DC and stepper motor drives.
Position and velocity servomechanisms.
Computer printers and plotters.
5.3 DTMF UNIT MODULE
-
8/3/2019 Kapil Project
38/61
The parts in this module
are
1. IC MT8870 - 1
2. Red LEDs - 5
3. White LEDS - 1
4. Resistors
1 kohm - 7
3
.
4
.
1
.
5
.
2
.
6
.
7.
-
8/3/2019 Kapil Project
39/61
10 kohm - 1
22 kohm - 3
100 kohm - 1
330 kohm - 1
5. Crystal (3.5791) - 1
6. Capacitors (22pF) - 4
7. Connector - 1
5.3.2 DTMF SIGNALLING
-
8/3/2019 Kapil Project
40/61
Dual-tone multi-frequency signaling (DTMF) is used for telecommunication
signaling over analog telephone lines in the voice-frequency band between
telephone handsets and other communications devices and the switching center.
The version of DTMF that is used in push-button telephones for tone dialing is
known as Touch-Tone, first used by AT&T in commerce as a registered
trademark, and is standardized by ITU-T Recommendation Q.23. It is also known
in the UK as MF4.
It is a tone consisting of two frequencies superimposed. Individual frequencies
are chosen such that it is easy to design filters and easy to transmit the tones
through a telephone line having bandwidth of approximately 3.5 kHz. DTMF was
not intended to be used for data transfer, it was meant to be used for sending the
control signals along the telephone line. With standard decoders it is possible to
send 10 beeps per second i.e., five bits per second. DTMF standard specifies
50ms tones and 600ms duration between two successive tones. The multiple tones
are the reason for calling the system multi frequency.
Note that the last column is not commonly seen in the telephones that we used,
but telephone exchanges use them quite often. Nowadays, DTMF is used for
http://en.wikipedia.org/wiki/Signalling_(telecommunications)http://en.wikipedia.org/wiki/Signalling_(telecommunications)http://en.wikipedia.org/wiki/Telephonehttp://en.wikipedia.org/wiki/Automatic_telephone_exchangehttp://en.wikipedia.org/wiki/Push-button_telephonehttp://en.wikipedia.org/wiki/Push-button_telephonehttp://en.wikipedia.org/wiki/ITU-Thttp://en.wikipedia.org/wiki/Q.23http://en.wikipedia.org/wiki/Telephonehttp://en.wikipedia.org/wiki/Automatic_telephone_exchangehttp://en.wikipedia.org/wiki/Push-button_telephonehttp://en.wikipedia.org/wiki/ITU-Thttp://en.wikipedia.org/wiki/Q.23http://en.wikipedia.org/wiki/Signalling_(telecommunications)http://en.wikipedia.org/wiki/Signalling_(telecommunications) -
8/3/2019 Kapil Project
41/61
dialing the numbers in telephones, configuring telephone exchanges etc. A CB
transceiver of 2.7 MHz is normally used to send floating codes. DTMF was
designed to be able to send the codes using microphone. Each beep (or digit you
dial on the telephone) is composed of two concurrent frequencies, which are
superimposed on amplitude. The higher of the two frequencies is normally aloud
by 4dB, and this shift is termed as twist. If the twist is equal to 4dB, the higher
frequency is loud by 4dB. If the lower frequency is loud, then the twist is said to
be negative.
GeneratingDTMF
DTMF signals can be generated through dedicated ICs or by using RC networks
connected to a microprocessor. MT8880 is an example of a dedicated IC. But
getting the latter method work is a bit difficult if high accuracy is needed. The
crystal frequency needs to be sacrificed for a non standard cycle length. Hence
this method is used for simple applications. Most often, a PIC micro could be
used for the above purpose.
DecodingDTMFDetecting DTMF with satisfactory precision is a hard thing. Often, a dedicated IC
such as MT8870 is used for this purpose. It uses two 6th order band-pass filters
using switched capacitor filters and it suppresses any harmonics. Hence they can
produce pretty good sine waves from distorted input. Hence it is preferred. Again
microprocessors can also be used, but their application is limited.
5.3.3FUNCTIONING OF IC MT8870
-
8/3/2019 Kapil Project
42/61
FUNCTIONAL DESCRIPTION
The CAMD MT8870/70C DTMF Integrated Receiver provides the design
engineer with not only low power consumption, but high performance in a small
18-pin DIP, SOIC, or 20-pin PLCC package configuration. The CM8870/70Cs
internal architecture consists of a band-split filter section which separates the high
and low tones of the received pair, followed by a digital decode (counting) section
which verifies both the frequency and duration of the received tones before
passing the resultant 4-bit code to the output bus.
DECODER SECTION
The MT8870/70C decoder uses a digital counting technique to determine the
frequencies of the limited tones and to verify that these tones correspond to
standard DTMF frequencies. A complex averaging algorithm is used to protect
against tone simulation by extraneous signals (such as voice) while providing
tolerance to small frequency variations. The averaging algorithm has been
developed to ensure an optimum combination of immunity to talk-off and
tolerance to the presence of interfering signals (third tones) and noise. When the
detector recognizes the simultaneous presence of two valid tones (known as
signal condition), it raises the Early Steering flag (ESt). Any subsequent loss
of signal condition will cause ESt to fall.
5.4BLUETOOTH WIRELESS HEADSETS
-
8/3/2019 Kapil Project
43/61
A headset is a headphone combined with a microphone. Headsets provide the
equivalent functionality of a telephone handset with hands-free operation.
Headsets typically have only one speaker like a telephone, but also come with
speakers for both ears. They have many uses including in call centers and other
telephone-intensive jobs and for personal use at the computer to facilitate
comfortable simultaneous conversation and typing.
TYPES OF HEADSET
Headsets can come in single-earpiece and double-earpiece designs. Single-
earpiece headsets are known as monaural headsets. However, double-earpiece
headsets come in both stereo type (two channels of audio signal, one for each
earpiece) orbinauraltype (the same audio channel for both ear-pieces).
Professional users may choose to wear monaural headsets because they free up
one ear, so they can be more conscious of their work surroundings. Telephone
headsets come in only monaural type for double-earpiece designs because
telephone offers only single-channel input and output, so all double-earpiece
telephone headsets are binaural.
However, for computer or other audio applications, where the sources offer two-
channel output, stereo headsets are the norm. Telephone headsets generally use
150-ohm loudspeakers with a narrower frequency range, so sound outside the
voice band is less audible to reduce background noise. Stereo computer headsets,
on the other hand, use 32-ohm loudspeakers which have a much broader
frequency range, and is more suitable of music listening.
http://en.wikipedia.org/wiki/Headphonehttp://en.wikipedia.org/wiki/Microphonehttp://en.wikipedia.org/wiki/Call_centershttp://en.wikipedia.org/wiki/Monauralhttp://en.wikipedia.org/wiki/Monauralhttp://en.wikipedia.org/wiki/Stereohttp://en.wikipedia.org/wiki/Binaural_recordinghttp://en.wikipedia.org/wiki/Binaural_recordinghttp://en.wikipedia.org/wiki/Loudspeakershttp://en.wikipedia.org/wiki/Frequency_rangehttp://en.wikipedia.org/wiki/Voice_bandhttp://en.wikipedia.org/wiki/Headphonehttp://en.wikipedia.org/wiki/Microphonehttp://en.wikipedia.org/wiki/Call_centershttp://en.wikipedia.org/wiki/Monauralhttp://en.wikipedia.org/wiki/Stereohttp://en.wikipedia.org/wiki/Binaural_recordinghttp://en.wikipedia.org/wiki/Loudspeakershttp://en.wikipedia.org/wiki/Frequency_rangehttp://en.wikipedia.org/wiki/Voice_band -
8/3/2019 Kapil Project
44/61
A Typical Bluetooth Headset
Most users have heard about Bluetooth, and although this technology was
designed originally for a much wider application, it has today become largely for
voice transmission (a notable exception to this would be the use of Bluetooth in
the Nintendo Wiimote). The reason for this general exclusivity is because of the
power/range settings of Bluetooth. Bluetooth uses 2.4 GHz RF, similar to WLAN
or Wi-Fi; however, by default it is set for a very close proximity usage for power
consumption benefits. This deficiency for a longer-range coverage made
bluetooth technology un-desirable for data transmission. As nowadays, more and
more mobile phones come equipped with bluetooth, this technology has become acommon wireless profile for wireless mobile phone headsets only.
-
8/3/2019 Kapil Project
45/61
A Stereo Bluetooth Headset
When choosing a Bluetooth headset users should be aware that bluetooth headsets
come in different types as well. Standard bluetooth headset's using version 1.0 or
1.1 are often a single-side monaural earpiece, which can only access the
Headset/handsfree profile of Bluetooth. Depending on the phone's operating
system, this type of headset will either play music at a very low quality (because
the phone is converting it into a voice signal) or will be unable to play music at all
(because the phone cannot perform such a conversion). Users who need a stereo-
music playing Bluetooth headset should look for a headset with the A2DP profile.
Users should note that some A2DP-equipped headsets will automatically de-
activate the microphone function during music-listening, so if these headsets are
paired to a computer via bluetooth connection, the headset may either disable the
stereo function or the microphone function.
http://en.wikipedia.org/wiki/A2DPhttp://en.wikipedia.org/wiki/A2DP -
8/3/2019 Kapil Project
46/61
Bluetooth Wireless Desktop Solutions
Some developers have offered complete desktop solutions using Bluetooth
technology. With a base-station that connects via cables to the fixed-line
telephone and also the computer via soundcard, users with any bluetooth headset
can pair their headset to the base-station, hence enabling them to use a single
headset for both fixed-line telephone and computer VoIP communication. This
type of solution, when used together with a multiple-point bluetooth headset
enables user to use a single bluetooth headset to communicate in
Telephone/Computer/Mobile.
There are now Bluetooth office headsets that incorporate Class 1 Bluetooth into
the base station so that when using with a Class 1 Bluetooth headset, the user can
get a greater distance from the phone or computer; generally around 100 feet
compared to the 33 feet of Class 2 Bluetooth, which is what most Bluetooth
headsets run on. The headsets that come with these base stations connect to cell
phones via Class 2 Bluetooth, so you still get the same 33 foot range from your
cell phone.
-
8/3/2019 Kapil Project
47/61
5.5 SENSOR MODULE
The sensor is an array of 3 IR LED-Photodiode pairs arranged in the form of aninverted V. The output of each sensor is fed into an analog comparator with the
threshold voltage (used to calibrate the intensity level difference of the line with
respect to the surface). These 3 signals (from each photo-reflective sensor) is
given to a comparator, the output of which goes to the microcontroller.
This sensor can be used for most indoor applications where no important ambient
light is present. For simplicity, this sensor doesn't provide ambient light
immunity, but a more complicated, ambient light ignoring sensor should bediscussed in a coming article. However, this sensor can be used to measure the
speed of object moving at a very high speed, like in industry or in tachometers. In
such applications, ambient light ignoring sensor, which rely on sending 40 KHz
pulsed signals cannot be used because there are time gaps between the pulses
where the sensor is 'blind'...
The solution proposed doesn't contain any special components, like photo-diodes,
photo-transistors, or IR receiver ICs, only a couple if IR leds, an Op amp, a
transistor and a couple of resistors. In need, as the title says, a standard IR led is
used for the purpose of detection. Due to that fact, the circuit is extremely simple,
and any novice electronics hobbyist can easily understand and build it.
5.5.1OBJECT DETECTION USING IR LIGHT
It is the same principle in ALL Infra-Red proximity sensors. The basic idea is to
send infra red light through IR-LEDs, which is then reflected by any object in
front of the sensor.
Then all you have to do is to pick-up the reflected IR light. For detecting the
-
8/3/2019 Kapil Project
48/61
reflected IR light, we are going to use a very original technique:we are going to use another IR-LED, to detect the IR light that was emitted from
another led of the exact same type.
This is an electrical property of Light Emitting Diodes (LEDs) which is the fact that a
led Produce a voltage difference across its leads when it is subjected to light. As if it
was a photo-cell, but with much lower output current. In other words, the voltage
generated by the leds can't be - in any way - used to generate electrical power from
light, It can barely be detected. Thats why as you will notice in the schematic we are
going to use a Op-Amp (operational Amplifier) to accurately detect very small
voltage changes.
5.5.2 SENSOR CIRCUIT
The resistance of the sensor decreases when IR light falls on it. A good sensor will
have near zero resistance in presence of light and a very large resistance in absence of
light. We have used this property of the sensor to form a potential divider.
The potential at point 2 is Rsensor / (Rsensor + R1). Again, a good sensor circuit
should give maximum change in potential at point 2 for no-light and bright-light
conditions. This is especially important if you plan to use an ADC in place of the
-
8/3/2019 Kapil Project
49/61
comparator. To get a good voltage swing , the value of R1 must be carefully chosen.
If we assume Rsensor = a, when no light falls on it and Rsensor = b, when light
falls on it. The difference in the two potentials is: Vcc * { a/(a+R1) - b/(b+R1) }
Relative Voltage Swing = Actual Voltage Swing / Vcc
= Vcc * { a/(a+R1) - b/(b+R1) } / Vcc
= a/(a+R1) - b/(b+R1)
Figure 5.3: Schematic of a single sensor
5.6 WIRELESS CAMERA
-
8/3/2019 Kapil Project
50/61
A wireless camera is a type of video camera that does not require the use of cables or
external wires for connection to related equipment. Wireless cameras offerconvenience when the placement of such cables would be difficult or even
impossible. Some wireless cameras use batteries, making them totally independent of
power outlets as well. Furthermore, they are portable and can be moved from location
to location quite easily.
Wireless cameras function similarly to other types of wireless devices. The exception
to the similarity, however, is that they send radio signals that are decoded into video
data. Wireless cameras are often used for surveillance, though some people purchase
them just for fun. Some wireless cameras are compatible with personal computers
(PCs) and are used to serve data streams tocomputerapplications or the Internet.
A wireless camera may be a good choice for video surveillance. This type of camera
can be used for both home and business, providing good surveillance coverage while
offering easy installation. Keep in mind, however, that some wireless cameras still
require connection to a power outlet. If connecting to a power outlet isnt convenient
or will give away the location of a camera you want hidden, consider purchasing a
battery-powered wireless camera instead.
Wireless cameras are also popular for web camming. Used for this purpose, a wireless
camera owner can allow another Internet user to both see and hear him or her using
Internet technology. Many individuals use wireless cameras to catch up with long-
distance relatives and friends, chat over the Internet with just about anyone, and even
participate in the online datingscene.
5.6.1 WIRELESS AV CAMERA
http://www.wisegeek.com/what-are-personal-computers.htmhttp://www.wisegeek.com/what-is-pcs.htmhttp://www.wisegeek.com/what-is-a-computer.htmhttp://www.wisegeek.com/what-is-a-computer.htmhttp://www.wisegeek.com/what-should-i-know-about-online-dating.htmhttp://www.wisegeek.com/what-should-i-know-about-online-dating.htmhttp://www.wisegeek.com/what-are-personal-computers.htmhttp://www.wisegeek.com/what-is-pcs.htmhttp://www.wisegeek.com/what-is-a-computer.htmhttp://www.wisegeek.com/what-should-i-know-about-online-dating.htm -
8/3/2019 Kapil Project
51/61
BASIC
ANTENNA
INTERFACE
DC INPUT
PLUG
VIDEO
OUTPUT
AUDIO
OUTPUT
FREQUENCY
CONTROLLER
POWER
INDICATORY
LIGHT
-
8/3/2019 Kapil Project
52/61
SPECIFICATION PARAMETERS
VIDEO OUTPUT : 75 / 1 Vp-p
AUDIO OUTPUT : 10k / 200 M Vp-p
POWER CONSUMPTION : LESS THAN 2W
WORK TEMPERATURE : 0 ~ 40C
SIZE : 115 X 60 X 20 mm
WEIGHT : 150 g
RANGE : 60 m
OPERATING INSTRUCTIONS
CAMERA TRANSMITTER
1. Install the camera transmitter toward the direction you need to monitor.
2. Insert the DC8V500mA power adaptor into the inter flow power plug, and
insert its DC output plug into the DC input plug of the camera transmitter to
put through the circuit.
RECEIVER
1. Insert the antenna into the antenna interface of the receiver and fasten it.
2. Use AV line to connect the audio and video output interface of the receiver
with the audio and video input interface of the TV set or monitor.
3. Insert the DC9V/12V 500mA power adaptor into the interflow power plug, and
insert its DC output plug into the DC input plug of the receiver to put through
-
8/3/2019 Kapil Project
53/61
the circuit, and at the moment the power indicatory light shines.
4. Adjust the frequency controller of the receiver to the sending frequency of the
corresponding camera transmitter with hands and you can get the picture and
sound by the TV set. Adjust the supervision position of the camera transmitter
to the supervision object, and you can make effective supervision.
THE MATTER NEEDS PAYING ATTENTION TO
1. The two kinds of power adaptors of DC9V/12V500mA and DC8V500mA must
not be mix-used, in order to avoid to cause the circuit damage of the camera
transmitter.
APPLICATIONS
This product is suitable for supervision of the places such as supermarkets,
department stores, homes, workshops, hospitals, and so on.
(6)CODING
-
8/3/2019 Kapil Project
54/61
ORG 00H
OBS: MOV P0, #1111 0101B
JNB P0.2, ST
AJMP OBS
ST: MOV P0, #1111 1111B
MOV A, P1
CJNE A, #1111 1100B, OBS
AJMP DTMF
DTMF: MOV A, P1
FW: CJNE A, #11110010B, BK
MOV P0, #11110101B
AJMP DTMF
BK: CJNE A, #11111000B, RT
MOV P0, #11111010B
AJMP DTMF
RT: CJNE A, #11110110B, LT
-
8/3/2019 Kapil Project
55/61
MOV P0, #11111001B
AJMP DTMF
LT: CJNE A, #11110100B, STP
MOV P0, #11110110B
AJMP DTMF
STP: CJNE A, #11110101B, CHECK
MOV P0, #11111111B
AJMP DTMF
CHECK: CJNE A, #1111 1011B, DTMF
AJMP OBS
LIMITATIONS
-
8/3/2019 Kapil Project
56/61
Different DTMF characters have different level of effectiveness in
transmission, i.e., one DTMF tone may have a larger effective
communication area than the other. Therefore, in estimating the effectiveness
region of the whole DTMF character set, communication is considered failed
when two or more tones out of 16 are not transmitted successfully
Choice of Sensors sensitivity is made in the hardware abstraction and cannot
be changed by software.
Calibration is difficult, and it is not easy to set a perfect value.
The steering mechanism is not easily implemented in huge vehicles and
impossible for non-electric vehicles (petrol powered).
Lack of a four wheel drive, makes it not suitable for a rough terrain.
Use of IR sensors makes it difficult for robot to sense during day light, it
senses the Infrared from sunlight as well as IR use makes it hard to debug a
faulty sensor.
Lack of speed control makes the robot unstable at times.
APPLICATIONS
-
8/3/2019 Kapil Project
57/61
Industrial automated equipment carriers.
Entertainment and small household applications.
Automated cars.
Tour guides in museums and other similar applications.
Second wave robotic reconnaissance operations.
Autopilot modes of airplanes and helipads
Spy robots in surveillance system
RESULT AND CONCLUSION
-
8/3/2019 Kapil Project
58/61
The Obstacle Avoider robot was finally completed. After detecting the object
movement of car is as desired by bluetooth enable mobile phone. A lot of effort
was put into the design, implementation and days of toil in front of the computer,
writing and debugging the code. The robot was finally running with a few glitches
here and there which were sorted in the later revisions of the firmware. The
Obstacle Avoiding robot still has a few shortcomings but achieves most of the
objectives.
We earned a lot of knowledge on micro-controllers, a deeper & clearer view of
the architecture, ports & all other functional blocks was achieved. Did a lot of
research on robotics. Had a peek look at all simple functional parts of the project
like the crystal oscillator, logic gates and the works. Well, these were the topics
that we have already dealt with, but we must be honest and admit that there were
various practical issues which one would learn only during a project. Theres a lot
of learning & yet not the end, learning is a continuous never ending process but is
definitely fun.
BIBLIOGRAPHY
-
8/3/2019 Kapil Project
59/61
1) WEBSITES REFERRED
www.google.com
All others are searched through GOOGLE.
The Seattle Robotics Society Encoder library of robotics articles:
http://www.seattlerobotics.org/encoder/library.html
Dallas Personal Robotics Group. Most of these tutorials and articles were
referred:
http://www.dprg.org/articles/index.html
http://www.dprg.org/tutorials/index.html
Go Robotics.NET, this page has many useful links to robotics articles.
http://www.gorobotics.net/articles/index.php
this site provides all information regarding components used in robotics
http://www.ikalogic.com
2) BOOKS
The 8051 microcontroller and Embedded System
http://www.google.com/http://www.seattlerobotics.org/encoder/library.htmlhttp://www.dprg.org/articles/index.htmlhttp://www.dprg.org/tutorials/index.htmlhttp://www.gorobotics.net/articles/index.phphttp://www.google.com/http://www.seattlerobotics.org/encoder/library.htmlhttp://www.dprg.org/articles/index.htmlhttp://www.dprg.org/tutorials/index.htmlhttp://www.gorobotics.net/articles/index.php -
8/3/2019 Kapil Project
60/61
by Muhammad Ali Mazidi second edition-PEARSON Education
Programming and Customizing the AVR microcontroller
by Myke Predko Second edition McGraw Hill
AVRmicro Mid-Range ATmega Family Reference Manual
by ATMEL
Design with AVR ATmega-16 microcontrollers
by John B. Peatman PEARSON Education
PIC Robotics, A beginners guide to robotics projects using the PICmicro
by John Iovine McGraw Hill
Digital logic and computer design
by M. Morris Mano - Prentice Hall of India PVT limited
Digital Systems Principles & applications
by Ronald J. Tocci Sixth Edition - Prentice Hall of India PVT limited
METHODOLOGY
-
8/3/2019 Kapil Project
61/61
The first idea was to use optical imaging (CCD cameras) to see the obstacle. This
was later given up due to various reasons including complexity and unavailability
of components. Later a choice was made to use an array of sensors which solved
most of the problems pertaining to complexity. Also to enhance efficiency in
detecting obstacle we use wireless camera.
The resistor values used in the sensor array were experimentally determined
rather than theoretical mathematical design calculations. This was done as the
data sheets of the proximity sensor was not available anywhere and most of the
parameters had to be determined experimentally.
The L298 chip is used as it was a much better option than forming an H-Bridge
out of discrete transistors, which would make the design unstable and prone to
risk of damage.
The 8051microcontroller was used as it is the only device I have a full practical
knowledge about, and most of all a RISC processor which are better suited for
realtime operations. Thus the midrange devices were chosen.
Software was coded day and night, deciding on a few algorithms and few tiny
details which gradually got the robot to do what was required.
The first idea to control the robots was to use RF circuits but due to certain
limitations we use DTMF technology which provides the robust control and large
working areas.
The project was entirely designed, created, soldered, tested and coded by us. For
which we are thankful for, as I have learnt much more in the processes and not to
mention the fun had.