Automated Step Climber

Department of Electronics and Telecommunication, BIT, Durg(C.G.)

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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.

http://en.wikipedia.org/wiki/Electric_motor

http://en.wikipedia.org/wiki/Reluctance_motor

http://en.wikipedia.org/wiki/Reluctance_motor


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CHAPTER 2

LITERATURE REVIEW


5

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


6

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

http://en.wikipedia.org/wiki/Georg_Ohm

http://en.wikipedia.org/wiki/Electrical_resistance#cite_note-0

http://en.wikipedia.org/wiki/Friction

http://en.wikipedia.org/wiki/SI

http://en.wikipedia.org/wiki/Ohm

http://en.wikipedia.org/wiki/Omega

http://en.wikipedia.org/wiki/Multiplicative_inverse

http://en.wikipedia.org/wiki/Electrical_conductance

http://en.wikipedia.org/wiki/Siemens_%28unit%29

http://en.wikipedia.org/wiki/Potential_difference

http://en.wikipedia.org/wiki/Ohm%27s_law

http://en.wikipedia.org/wiki/Electromagnetism

http://en.wikipedia.org/wiki/Electronics

http://en.wikipedia.org/wiki/Electric_charge

http://en.wikipedia.org/wiki/Electric_potential

http://en.wikipedia.org/wiki/Capacitor


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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

http://www.datasheets4u.com/


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Appendix

Documents

Automated Step Climber