Download - Automated Step Climber
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CHAPTER 1
INTRODUCTION
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INTRODUCTION
Human body is perfect combination of motion, balance, co-ordination and reflex. It
because human brain is so much developed that all these activities can take place in such
perfect co-ordination. With advancement in science we humans have created many
beautiful creations and robot happens to be one of them. Humans have developed robots
that can mimic humans. In the same context it is our humble effort to develop an electro-
mechanical autonomous robotic vehicle that can have multiple degree of freedom, which
enable it to move through various terrains.
Taking inspiration from NASA’s path finder robot we have tried to make a tone down
prototype which control its movement with help of microcontroller which properly co-
ordinate its motion.
In our project we have tried to built an electro-mechanical autonomous robotic vehicle,
which moves over the hurdles in front of it by sensing obstacle with help of sensing
circuit and taking controlled action with microcontroller ,which drives the motors to
make robot climb over the obstruction.
We have used many other chips to achieve this motion which we have described in the
component section.
This robotic vehicle could become a prototype for surveillance vehicle and other military
vehicles used for detection and detonation of mines .Since cost of this prototype is very
less thus it could be inducted in army easily and be made indigenously.Mainly ou project
is based on working of microcontroller for the automatic management and motors for
hardware management.
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1.1 Microcontrollers
Circumstances that we find ourselves in today in the field of microcontrollers had their
beginnings in the development of technology of integrated circuits. This development has
made it possible to store hundreds of thousands of transistors into one chip. That was a
prerequisite for production of microprocessors, and the first computers were made by
adding external peripherals such as memory, input-output lines, timers and other. Further
increasing of the volume of the package resulted in creation of integrated circuits. These
integrated circuits contained both processor and peripherals. That is how the first chip
containing a microcomputer, or what would later be known as a microcontroller came
about.
1.2 Stepper motor
A stepper motor (or step motor) is a brushless, synchronous electric motor that can divide
a full rotation into a large number of steps. The motor's position can be controlled
precisely, without any feedback mechanism .Stepper motors are similar to switched
reluctance motors
Stepper motors operate differently from normal DC motors, which rotate when voltage is
applied to their terminals. Stepper motors, on the other hand, effectively have multiple
"toothed" electromagnets arranged around a central gear-shaped piece of iron. The
electromagnets are energized by an external control circuit, such as a microcontroller. To
make the motor shaft turn, first one electromagnet is given power, which makes the gear's
teeth magnetically attracted to the electromagnet's teeth. When the gear's teeth are thus
aligned to the first electromagnet, they are slightly offset from the next electromagnet. So
when the next electromagnet is turned on and the first is turned off, the gear rotates
slightly to align with the next one, and from there the process is repeated. Each of those
slight rotations is called a "step," with an integral number of steps making a full rotation.
In that way, the motor can be turned by a precise angle.
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CHAPTER 2
LITERATURE REVIEW
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Literature Review
2.1Basic operation of circuit:
In above block diagram, as sensors are mounted on the robot for detecting the obstacle in
front of them. IRLED (Infra Red Light Emitting Diode) and Photodiode act as sensors
here. IRLED emitted light for detecting obstacle which is reflected back by obstacle and
is received by Photodiode. we use total three number of sensors.
From the reception of Photo diode voltage is generated, this generate voltage is feed to
comparator for comparing with the reference voltage. We use total three number of
comparator. Operational Amplifier (Op-Amp) IC LM324 is used for comprator After
comparing the output voltage is given to the Micro Controller’s input port.
Fig 1 :Block Diagram
If comparator output is high which is inputted to the Micro Controller 8052 so that
enabled the input pins. Micro Controller’s 12 ports are programmed for output ports.
S
E
N
S
O
R
S
Comparator 3
Comparator 2
Comparator 1
MI CRO
CONTROLLER
Motor Driver 2
Motor Driver 2
Motor Driver 1
M
O
T
O
R
S
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These output ports are used for input for Motor Driver. IC 293B is used for Motor
Driver.Motor Driver is used for the driving the motors which are mounted on the robot.
2.2 Circuit Diagram Explanation
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Fig 2 :Circuit Diagram
2.3 Single sided PCB layout of Automated Step Climber
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Fig 3 :Single sided PCB layout
2.4 Components Used
Semiconductors
IC1 : Atmel 89C52 microcontroller
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IC2 : LM324 comparator
IC3 : L293B motor driver
Photo diode : Qsd2030F
IR LED : Qed234
Resistors
R1-R6 : 470 ohms
R7-R13 : 5.6 kilo-ohms
R14-R26 : 10 kilo-ohms
R27 : 2.2 kilo-ohms
Capacitors
C1 : 0.33µF ceramic disk
C2
Miscellaneous
XTAL1 : 12MHz crystal
M1-M9 : 6V,30 rpm stepper motor
Battery : 12 V.
2.5 Components Description-
2.5.1 Atmel-89C52
Features
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• Compatible with MCS-51™ Products
• 8K Bytes of In-System Reprogrammable Flash Memory
• Endurance: 1,000 Write/Erase Cycles
• Fully Static Operation: 0 Hz to 24 MHz
• Three-level Program Memory Lock
• 256 x 8-bit Internal RAM
• 32 Programmable I/O Lines
• Three 16-bit Timer/Counters
• Eight Interrupt Sources
• Programmable Serial Channel
• Low-power Idle and Power-down Modes
Description
The AT89C52 is a low-power, high-performance CMOS 8-bit microcomputer with 8K
bytes of Flash programmable and erasable read only memory (PEROM). The device
is manufactured using Atmel’s high-density nonvolatile memory technology and is
compatible with the industry-standard 80C51 and 80C52 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 Flash on a monolithic chip, the Atmel AT89C52 is a powerful microcomputer
which provides a highly-flexible and cost-effective solution to many embedded control
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Fig 4:Pin configuration
Pin description:
VCC
Supply voltage.
GND
Ground.
Port 0
Port 0 is an 8-bit open drain bi-directional I/O port. As anoutput port, each pin can sink
eight TTL inputs.
Port 1
Port 1 is an 8-bit bi-directional I/O port with internal pullups.The Port1 output buffers can
sink/source four TTL inputs.When 1s are written to Port 1 pins, they are pulled high.
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Port 2
Port 2 is an 8-bit bi-directional I/O port with internal pullups.The Port 2 output buffers
can sink/source four TTL inputs.
Port 3
Port 3 is an 8-bit bi-directional I/O port with internal pullups.The Port 3 output buffers
can sink/source four TTL inputs.
RST
Reset input. A high on this pin for two machine cycles while
the oscillator is running resets the device.
ALE/PROG
Address Latch Enable 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.
PSEN
Program Store Enable is the read strobe to external program memory.When the AT89C52
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.
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 when 12-volt
programming is selected.
XTAL1
Input to the inverting oscillator amplifier and input to the internal clock operating circuit.
XTAL2
Output from the inverting oscillator amplifier.
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2.5.2 L293B
Features
n OUTPUT CURRENT 1A PER CHANNEL
n PEAK OUTPUT CURRENT 2A PER CHANNEL
(non repetitive)
n INHIBIT FACILITY
n HIGH NOISE IMMUNITY
n SEPARATE LOGIC SUPPLY
n OVERTEMPERATURE PROTECTION
DESCRIPTION
The L293B and L293E are quad push-pull drivers capable of delivering output currents to
1A per channel. Each channel is controlled by a TTLcompatible logic input and each pair
of drivers (a full bridge) is equipped with an inhibit input which turns off all four
transistors. A separate supply input is provided for the logic so that it may be run
off a lower voltage to reduce dissipation.
Fig 5: Pin configuration
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2.5.3 LM324
Features
Internally Frequency Compensated for Unity Gain
Large DC Voltage Gain: 100dB
Wide Power Supply Range:
LM224/LM224A, LM324/LM324A : 3V~32V (or 1.5 ~16V)
LM2902: 3V~26V (or 1.5V ~ 13V)
Input Common Mode Voltage Range Includes Ground
Large Output Voltage Swing: 0V to VCC -1.5V
Power Drain Suitable for Battery Operation
Description
The LM324/LM324A,LM2902,LM224/LM224A consist of four independent, high gain,
internally frequency compensated operational amplifiers which were designed
specifically to operate from a single power supply over a wide voltage range. operation
from split power supplies is also possible so long as the difference between the two
supplies is 3 volts to 32 volts. Application areas include transducer amplifier, DC gain
blocks and all the conventional OP Amp circuits which now can be easily implemented in
single power supply systems.
Fig 6 :Pin configuration.
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2.5.4 Photo diode
Features
PIN photodiode
Package type: T-1 3/4 (5mm lens diameter)
Wide reception angle, 40°
Daylight filter
Package material and color: black epoxy
High sensitivity
Peak sensitivity λ= 880nm
Radiant sensitive area: 1mm x 1mm
Fig 7:Package Dimension
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2.5.5 IR LED
FEATURES
�= 940 nm
Chip material =GaAs with AlGaAs window
Package type: T-1 3/4 (5mm lens diameter)
Matched Photosensor: QSD122/123/124
Medium Emission Angle, 40°
High Output Power
Package material and color: Clear, untinted, plastic
Ideal for remote control applications
Fig 8:Package Dimension
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2.5.6 Resistance
The electrical resistance of an object is a measure of its opposition to the passage of a
steady electrical current. An object of uniform cross section will have a resistance
proportional to its length and inversely proportional to its cross-sectional area, and
proportional to the resistivity of the material.
Discovered by Georg Ohm in the late 1820s,[1]
electrical resistance shares some
conceptual parallels with the mechanical notion of friction. The SI unit of electrical
resistance is the ohm, symbol Ω. Resistance's reciprocal quantity is electrical conductance
measured in siemens, symbol S.
The resistance of a resistive object determines the amount of current through the object
for a given potential difference across the object, in accordance with Ohm's law:
2.5.7 Capacitance
In electromagnetism and electronics, capacitance is the ability of a body to hold an
electrical charge.
Capacitance is also a measure of the amount of electric charge stored (or separated) for a
given electric potential. A common form of charge storage device is a two-plate
capacitor. If the charges on the plates are +Q and −Q, and V gives the voltage between
the plates, then the capacitance is given by
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2.6 Working
At initial position all the wheels are on the ground and microcontroller is programmed in
such a way that the robo moves forward till the sensor circuit detect any obstruction.
The sensor circuit consist of IR LED and phototransistor .The IR LED emits the IR
radiations ,when there no obstruction the phototransistor does not detect any reflected
radiation and the vehicle moves forward without any vertical motion.
When any obstruction comes in front of sensor mounted in front of wheel one the IR
radiation are reflected back from the obstruction which is picked up by phototransistor
.This phototransistor supplies a trigger signal to the comparator which conditions the
signal and supplies the signal to microcontroller.
The forward motion of the robo stops and microcontroller then detect the signal on a
programmed pin. According to programming controller send the signal to the motor
driver .The motor driver drives the rack and pinion which lifts the wheel set one from the
ground. The phototransistor detect the radiated IR radiations till the IR LED moves
above the obstacle. As the wheels thus IR LED moves above the obstruction no sensor
detect any signal thus forward motion of robo is initiated by the controller. Now the
second detector detect the obstruction and same action is repeated as in case of first
sensor.
Once the second wheel moves over the obstruction the center of gravity moves in such a
position that robo cannot topple. Thus in similar way third and last wheel climb over the
obstruction and the robo moves above the obstruction.
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Source code in “c” language
Mov P1,#0FF H
JB P1.0,L1
JB P1.1,L2
JB P1.2,L3
SETB P3.0
CLR P3.1
SETB P3.2
CLR P3.3
SETB P3.4
CLR P3.5
CLR P3.6
CLR P3.7
CLR P2.0
CLR P2.1
CLR P2.2
CLR P2.3
LOOP FOR L1
L1:CLR P3.0
CLR P3.2
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CLR P3.4
SETB P3.6
CLR P3.7
SJMP BACK
LOOP FOR L2
CLR P3.0
CLR P3.2
CLR P3.4
SETB P2.0
CLR P2.1
SJMP BACK
LOOP FOR L3
CLR P3.0
CLR P3.2
CLR P3.4
SETB P2.2
CLR P2.3
SJMP BACK
END
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CHAPTER 3
METHODOLOGY
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Methodology
3.1 Robo Layout
It Consists of-
1. RACK & PINION -> The combination of rack and pinion is used to make the up
and down motion of the pairs of the wheels.
2. FIBER COVER -> The fiber cover is used to keep the pinion fixed on rack by
providing fiber cover from both the sides.
3. RUBBER WHEELS – 3 pairs of rubber wheels are used i.e., 6 wheels are used in
the robot.
4. ALLUMINIUM FRAME -> Two alluminium frames are used to keep the racks
fixed in their positions.
5. ALLUMINIUM CYLINDERS -> Alluminium cylinders are used in the rubber
wheels to provide strength to the wheels.
6. MOTORS -> 30 r.p.m motors are used for the motion of the wheels.
7. Electronic Circuit-It contains microcontroller, sensor,few components.
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3.2 PCB Preparation
Rules for PCB design:-
1. The PCB layout should be as compact as possible so that the circuit does not
become bulky.
2. There should be no 900 turns of the track. If the track takes sharp then there is the
probability of the tracks stripping off the board.
3. There should be minimum use of jumpers.
4. Heat dissipating components should not be kept in the vicinity of heat sensitive
components. This may lead to unwanted variations in the heat dependant
parameters.
5. Appropriate spacing should be provided between the components.
6. Ground tracks must be the thickest, so that ground can be easily tacked.
7. Etching area should be as small as possible.
8. All the inputs and outputs should be kept together.
9. The PCB should be exposed for optimum time.
Steps in PCB design and fabrication:-
The following steps were involved:
Artwork preparation
Film making
Film developing
Exposing
Etching
Drilling
Soldering
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Artwork preparation:-
We design the PCB layout using PCB design software such as ULTIBOARD and take a
print out on either butter paper or simple white paper. The schematic is called ‘artwork’.
It should be proper without leaving any connection or making any excess connection or
shorts.
Film Making:-
Cut the photo sensitive Lithium film in the dark room according to the size of the layout,
keep the layout and the film over it in the ‘Film Making Unit’ for 7 sec. This has been
found to be the optimum time.
Film developing:-
Dip the lithium film into developer solution (consisting of solution A and B) in a tray for
2-3 minutes. Now take out his film from the tray and dip it into another Lithium fixer
solution for about 1-2 minutes. Dry it in air, Now the film is ready.
Exposing:-
The process of taking the impression of the Lithium film on the copper cladded board is
known as ‘Exposing’. Cut the copper laminated board as per requirement and rub it with
steel wool or sand paper to remove the oxidation. Dry it in the dryer machine at a
temperature of 40 C. Now keep this is the ‘Dip coating machine’ which contains a
mixture of Liquid photo resist and LPR thinner (1+1 liter). Again keep it in the dryer
machine. Now put the Lithium film and copper board in the exposing machine (first place
the lithium film and keep the copper board over it) for 90 seconds. Now take out this
copper board and dip it into a tray containing LPR blue dye.
Etching:-
Now, the exposed board is rinsed in the etching solution. The etching solution
constitutes concentrated FeCl3 with water. The copper cladded board is kept inside the
solution for about 10 minutes till all the excess copper is removed where as unexposed
copper remains intact on the board. This unexposed copper then makes the pattern that we
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finally see on the PCB. Now the prepared PCB is kept in water for some time to remove
dry acidic profile that may cause poor performance of assembly.
Drilling:-
The PCB is now ready for drilling operation. The holes are now drilled at the
places where the components are to be placed with the help of a PCB drilling machine
having a drill bit of 0.75mm or 1mm size. The size of the hole should be optimum, not
very large or very small. If the hole is too large in diameter, It will be difficult to solder
and a lot of will be consumed. On the other hand, if the hole is too small, we face
difficulties in inserting the components.
Testing and assembling of the unit:-
The PCB is checked for all interconnections using a multimeter. Any track that is
either broken or short is subsequently corrected. Components are mounted keeping in
mind the proper polarity and direction. Avoid contact between the components. Heat-sink
is to be put wherever required with a heat sink compound. After assembling the
components they are solded and thereafter cleaned with CTC liquid.
Soldering:-
Soldering is the process of joining two metallic conductors. The joint where the
two metal conductors are to be joined or fused is heated with a device known as ‘
soldering iron’ and then an alloy of tin and lead, called solder, is applied which on
melting covers the joint. The solder cols and solidifies quickly to ensure a good and
durable connection between the joined metals. Covering the joints with solder also
prevents oxidation.
How to solder:-
Good soldering practices are as important as proper assembly of any electronic circuit. A
poorly soldered joint or connection in an electronic circuit is the cause of most problems.
Given below are some steps that should be followed in good and correct soldering
practices :
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1) Keep the soldering iron hot during the working period and let is rest on its stand
when not in use.
2) Enough heat is applied to the joint so that the solder metal flows freely on the
joint.
3) Too much solder should not be used to avoid short circuits between tracks on the
PCB
4) Use of correct type of soldering iron and solder is important. Flux is used to avoid
dry soldering but we should avoid the use of excessive flux.
Advantages of Printed circuit boards:-
1) Printed circuit boards are of interest to industry because they are the common
denominator for almost all approaches to mechanized fabrication of electronic
equipment.
2) Their use has greatly reduced the labour required for the wiring of an electronic
circuit. This reduction is especially significant for various purposes from small
units in computers to guided missile equipment.
3) This can be manufactured uniformly because graphic art process provided
repeatable results.
4) Their uniformity improves the product through simplification of quality control.
5) Printed circuitry has helped to minimize unskilled labor and thus greatly reduced
one major cause of unreliability in electronic equipment (individually soldered
connections) by permitting the use of dip soldering rather than hand soldering
processes.
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CHARTER 4
Result and Discussion
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Result & Conclusion
We have divided this chapter in 2 parts
1. Mechanical part
2. Electronic part
Mechanical Part
The main challenge in building the mechanical part was tackling toppling problem of
robot while climbing the obstacle. We have solved this problem by making the skelton
fame by light weight aluminium and dividing section in a ratio which adjust the center of
gravity in forward direction while climbing, thus solving problem of toppling.
Electronic Part
We have achieved a synchronized and desired motion between different mechanical part
by the help of sensor circuit (IRLED and phototransistor) and microcontrollers. We have
also tackled the particle difficulties such as false triggering, synchronization of speed
between different parts through microcontroller programming.
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CHAPTER 5
Application
and
Scope of further Work
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Application and Future Enhancements
Application
1. Military use for spying and mines detection and detonators.
2. Exploration on various terrains and places unsuitable for existence of human.
3. Prototype for higher and sophisticated advance machines.
Future Enhancement
1. Additional sensor can be mounted which could help in mineral exploration and
extraction process.
2. Remote controlled circuit could be mounted along with option of automated mode.
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BIBLIOGRAPHY
BOOKS :-
1. Electronics For You Magazine
2. C Programing for Microcontrolllers by Joe Pardue
WEBSITES :-
1. www.google.com
2. www.atmel.com
3. www.datasheets4u.com
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Appendix