AUTONOMOUS LIGHT SEEKING ROBOT - Robosoft Systems

Skill Level: Intermediate

Soldering:

Required

AUTONOMOUS LIGHT SEEKING ROBOT

Free ZENER

& FLED Solar

Engine Inside

Battery not required

SOLAR BUG is a Educational Robotics Kit.

Robosoft Systems employs high performance motors and electronic equipment in SOLAR BUG.

Robosoft Systems cannot be held liable for damages or injuries caused by the improper or un recommended use of SOLAR BUG.

All advanced modifications or deviations from the directions contained herein are considered to be at the risk of the SOLAR BUG owner, and not supported by Robosoft Systems.

This is the SOLAR BUG Owners Manual v1.00.June09 for the robot SOLAR BUG.

For More information go to http://www.robosoftsystems.co.in

or contact us at [email protected]

All rights reserved.

Owners Manual SOLAR BUG

AUTONOMOUS LIGHT SEEKING ROBOT

CONTENTS

Safety Instruction 1

About Us 2 Features 3

Introduction 4

Kit Contains 8

Solar Energy Facts 10

Circuit Explanation 14

Soldering Tips 25

Robot Assembly 29

Troubleshooting Guide 43 Scratch your Head 49

TOPIC PAGE NO.

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SOLAR BUG

www.robosoftsystems.co.in

Safety Instruction

Now your proud owner of SOLAR BUG the Light Crawler Robot. This manual contains the assembly of the solar bug and operating cautions.

CAUTION

• Please read this manual carefully to ensure that assembly and operations are performed in a safe and Correct manner.

• Do not expose the Components to excessive heat

caused by heating equipments. • Do not drop your bug or allow objects to fall on your

bug as this may damage the components mounted on bug. • Do not allow the Solar Bug to come in contact water

As it may cause major damage. • Robosoft Systems is not responsible for any loss or

malfunction of components or if the product gets damaged due to transportation.

• Do not use any cleaning agents containing alcohol,

ammonia, benzene, or abrasives as these may harm the Bug.

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SOLAR BUG


About Robosoft Systems

Robosoft Systems ® is a young & dynamic start-up still in its nascent stage. It all started with a vision back in 2008 when a group of young engineer’s bitten by the entrepreneurship bug came together for transforming their dreams into reality, & it had to be the dynamic field of Robotics just like the young minds themselves.

The company is creating waves in the field of Educational & Industrial Robotics with a wide range of intriguing products. We at Robosoft believe in passing on the good knowledge. With 70% of the countries population being young generation, the future lies in the schools & colleges, hence we have been conducting WORKSHOPS at schools & colleges all across INDIA many of them in association with the most respected media organisation TIMES OF INDIA (NIE). The WORKSHOPS have become an instant hit since it provides the students the ultimate stage for understanding science to its core concepts & going beyond the limits of textbooks.

Before launching solar bug in market Robosoft Systems have conducted workshop in partnership with TECHFEST 09 IIT Powai across the country and made 800 bugs in the process.

Company has had path breaking success lead by a dedicated team of R&D engineers. The company has been launching products defying cutting edge technology. This pursuit of excellence has won the company many accolades. Recently the company entered into a joint venture with SOLARBOTICS–CANADA, a company which deals in high end SOLAR ENERGY ROBOTS.

Managing Partner

Robosoft Systems®

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SOLAR BUG


FEATURES

• Autonomous Robot.

• Light Seeking Capability.

• Avoiding Obstacle.

• Crawling locomotion.

• Solar Powered.

• Battery Not Required.

• Simple to assemble.

• Compact in size.

• Programming Not Required.

Statutory Warning:

This is a highly addictive robotics kit; please do your school homework before starting.

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SOLAR BUG


*Note: µC stands for Microcontroller.

The SOLAR BUG is an AUTONOMOUS ROBOT which is classified under BEAM

ROBOTICS.

Robotics

Manually Controlled Robot

Autonomous Robot

Semi Autonomous Robot

PC based robots

Solar bug

BEAM Robots

µC based robots

Introduction

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SOLAR BUG


• BEAM Robotics is a field of robotics where the robot does not have a “traditional”

brain (i.e. a microprocessor) and does not look like a "traditional" robot (i.e.: no

blinking lights).

• No microprocessor means there isn't any programming to contend with, or worries

about losing all your programming because the battery ran low.

• Being solar-powered and lacking an “off” switch means that a BEAM creature will

do what it's designed to do as long as there is sufficient light, regardless if there's

a person watching it or not.

• This means you can leave your robot alone for a while, and when you come back,

it may be in a totally new and unexpected position (or for that matter, could be

down-right missing)...

The name BEAM is an acronym for

B - Biology

E - Electronics

A - Aesthetics

M - Mechanics

BEAM robots are solar powered which may or may not require mechanical

switch to turn it off.

The most striking feature of these robots is that it does not make use of micro

computer chips or in simple terms these robots does not need any programming to

function flawlessly .

It is very simple to operate and to tune the Robot according to your needs.

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SOLAR BUG


BEAM is the brainchild of Dr. Mark W. Tilden formerly a researcher at Los Alamos National Laboratory, where his invention was used to simulate biological neuron behaviours. Basically Tilden's circuits are mostly used in various solar based robots with several important features making it a new revolution in the field of autonomous robots.

The basic principles of BEAM Robotics is,

1) Use the lowest number possible of electronic elements ("keep it simple")

2) Recycle and reuse techno scrap.

3) Use radiant energy (such as solar power).

Audiotropes: React to sound source.

Phototropes: React to light source.

E.g. Solar bug

Radiotropes: React to radio frequency.

Thermotropes: React to heat source.

Types Of Beam Robots :

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SOLAR BUG


ROBOSOFT SYSTEMS’ SOLAR BUG V1.0 self-contained robot that is powered

entirely by solar energy has light-sensing directional optics (eyes), and a pair of obstacle

avoidance sensors.

The solar bug is an autonomous robot with crawling locomotion, which always

follows light.

The name “SOLAR BUG” came about from the original prototype being powered

by a solar panel. This version is even faster due to the updated “Miller engine” Solar

engine that makes the robot speed over 2 feet a minute in sunlight! Almost every BEAM

creature makes use of a circuit called a Solar Engine.

Solar powered robots need solar-engines (relaxation oscillator) because most

robots do not get enough power from the solar cells. Have you tried to hook up a small

calculator solar cell with a motor ? Nothing happens. It's because the motor needs more

energy to turn it on. So they need to use solar-engine to save up enough power to move,

even in full sunlight.

Without a solar-engine, the solar robot probably be stand still on the day of

performance. By using a solar-engine, you can also use a much smaller solar cell, even

the solar cell from the solar-calculator !!

Thus solar engine is a circuit that digests the energy from a solar cell and turns it

into bursts of motion. Your SOLAR BUG uses two Miller engines, one for each motor.

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SOLAR BUG


1381 Q Voltage Trigger IC (Qty2)

1000uf Electrolytic capacitor (Qty1)

Coreless Motors (Qty2)

100K Trim Pot (Qty1)

1N4148 Diode (Qty2)

Solar Sensor (Qty2)

3904 NPN Transistor (Qty2)

0.22pf Ceramic Capacitors

Sr. no. List Of Components Specifications Qty Check list

2 Electrolytic Capacitor 1000μF/16V 1 3 Pager Motor 9000 RPM at 1.5V 2 4 1381 Q Voltage Trigger Ton-4.1V and Toff-3.8V 2 5 Trim Pot 100 K variable Resistor 1 6 Ceramic Capacitor 0.22μF 2 7 1N4148 Ge Diodes 0.3V 2

8 Solar Sensors Reverse Voltage-30V, Power

dissipation-100 mW 2

9 3904 NPN Transistor Emitter Base Voltage 5V 2

1 User manual Required to make bug 1

Note:

Electronic Components:

Kit Contains

2

4

3

5

7

8 9

6

• Please put a check mark ( )after verifying all the components

• Do not confuse between the IC 1381 & transistor 3904 .

• You can use magnifying glass to read the name of components.

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SOLAR BUG


Multi Strand Wire

Motor Mount

Solar Panel

Heat Shrink Tubing

PCB

Whiskers

Berg Strip

Double Sided Tape

Single Strand Wire

Sr no. Items Purpose Qty Check list

1 Whiskers Touch sensor 2

2 Gold Berg strip For holding the whiskers 2

3 Heat shrink tubing For grip and non

conductivity of whiskers 10cm

4 6V,33mA Solar

Panel For converting light

energy into electricity 1

5 Flexible Paper PCB Thickness=0.3mm

For mounting all the components according to the bug structure.

1

6 Motor Mounts For holding the motors 2

7 Double sided tape For pasting the solar panel

on the bug. Small piece

8 Single Strand Wire For holding the PCB 1

9 Multi Strand Wires For solar panel connection Twisted pair

Note: Please put a check mark ( )after verifying all the components

Miscellaneous Items:

1

2

3

6

4

7

8

5 9

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SOLAR BUG


SOLAR ENERGY FACTS

Solar power - energy from the Sun

Introduction: We've used the Sun for drying clothes and food for thousands of years, but only recently have we been able to use it for generating power. The Sun is 150 million kilometres away, and amazingly powerful. Just the tiny fraction of the Sun's energy that hits the Earth (around a hundredth of a millionth of a percent) is enough to meet all our power needs many times over. In fact, every minute, enough energy arrives at the Earth to meet our demands for a whole year - if only we could harness it properly.

What does solar energy mean? Solar energy just means energy (light and heat) that comes from the sun. There are as many different ways to use solar energy as you have ideas in your head. What gets you hot laying on the beach on a summer day? Solar energy. What gets your car hot when it's parked in the sun with the windows closed? Solar energy. What makes your solar calculator go? Solar energy. What makes the giant solar panels on satellites work? Solar energy. What makes plants grow? Rain and... solar energy. What makes the clouds that make the rain? You got it! Solar energy. What sets a blade of glass under a magnifying glass on fire? Yup, solar energy. And on and on.

Solar Energy Facts

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SOLAR BUG


How it works: There are two main ways in which we use the Sun’s energy: 1] Solar Cells: Really called “photovoltaic”, “PV” or “photoelectric” cells that convert light directly into electricity

2] Solar water heating where heat from the Sun is used to heat water in glass panels on your roof. This means you don't need to use so much gas or electricity to heat your water at home.

What if I want my solar panel to make electricity at night, or on cloudy days?

When the sun stops shining on your solar panel, its electrons stop moving and electricity stops flowing. So what do you do if you want to be able to read or watch television at night? (But you don't watch television, do you?) What stores the electricity in a flashlight? Right! A battery! And that's exactly what people do with solar panels... they attach batteries. The batteries are big, heavy, rectangular boxes, sort of like car batteries. Electricity from a solar panel flows into attached batteries while the sun shines, and then the stored electricity in the batteries can be used at night, or when the sun is behind the clouds.

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SOLAR BUG


#Fact1: If you grab hands with a friend and make a circle with your arms. The sunlight shining through the circle carries 1,000 watts of power. This is the most important number in solar power, the Solar Constant. It is the maximum power you can harvest from sunlight. To scientists, it is 1000 watts per meter squared. To you, it is the amount of sunlight power you and a friend can encircle. With 1,000 watts you can run ten bright light bulbs or one hair dryer. 1,000 watts is little more than one horsepower. And, along this vein, a horse lying on its side absorbs one horsepower of sunlight. Standard solar cells harvest one-tenth of this energy and convert it into electric power. So by using a solar cell you get 100 watts. High-tech solar cells harvest over 300 watts. #Fact2: Solar cells provide the energy to run satellites that orbit the Earth. These give us satellite TV, telephones, navigation, weather forecasting, the internet and all manner of other facilities.

Do you know?

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SOLAR BUG


Sun is 109 times bigger

than the Earth.

Do you know?????...

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SOLAR BUG


Before we actually go into the detailed explanation of circuits, let us first understand what solar engines are all about. At the heart of most solar-powered robots is a circuit called solar engine (also called as relaxation oscillators etc). The purpose of a solar engine is to act like a power "savings account" -- a small amount of incoming energy is saved up until a useable amount is stored. This stored energy is then released in a burst, in order to drive some useful work (in our case Motor). The solar engine has a number of advantages: 1) A solar-powered robot can be made to work, even in relatively-low light levels.

2) Solar cell size is minimized.

3) Saves money.

4) Saves weight.

5) Allows room for the solar cell to be ruggedized.

Why we need solar engine???

If you can remember, an engine is a device which converts any form of energy into mechanical output. So in our project we have to convert solar energy into mechanical out-put (motion of motor).

Solar engines are like water dam where, as the water reaches a specific level the dam is released, similarly solar engines monitor the charge stored in a circuit and once a specific level is achieved the charge is released.

Different types of Solar Engines:

1) Zener Engine.

2) FLED Engine.

3) Miller Engine.

Circuit Explanation

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SOLAR BUG


Lets See how solar Engine Works...

Every Solar Panel has some Finite Voltage and Current Ratings.

In our case it is 6.7V and 33mA

If I connect a Motor of 1.5 volts across solar panel will it run?

Yes...

It will run but the problem is if the intensity of light is not constant (sufficient) motor will not run continuously (as current depends on light intensity).

So that means we require something that can store energy.

So even if light intensity is not constant we can still run the motor by storing the charge in some storing element like capacitor.

So now after adding the capacitor will the motor run???

No ,motor will not run as current will not be sufficient to run the motor .Most of Current is flowing through the motor due to low resistance path so capacitor will not charge.

So there should be a switch which will allow the capacitor to charge first!!!!!!

6.7v

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SOLAR BUG


We need to add a switch in series with the motor to charge the capacitor when the switch is open and once it charges we can close the switch so that the motor starts running, utilizing the charge stored in capacitor.

But is it feasible to add ON/OFF switch ????

No! because if we add a switch then we will have to turn it ON or OFF our self all the time, but we want our robot to be autonomous!!!!

So rather than adding an ON/OFF switch we can connect a transistor in series with the motor because transistor can also act as a switch and along with it we will add a triggering circuit to fire after the capacitor charges to a required voltage. Triggering

Circuit

So what should be there in a triggering circuit ????

Lets see how the triggering circuit will make my robot Autonomous!!!!!!!!!

Triggering Circuit

Signal to NPN

Monitoring capacitor voltage

Current direction

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SOLAR BUG


1. Zener engine: The circuit shown below is the first autonomous circuit in BEAM Robotics discovered by Mark Tilden. The circuit uses a positive feedback loop between two transistors (NPN and PNP) and Zener Diode is used to trigger this loop. As zener is used as the triggering component the circuit is called as Zener Engine.

Note: Prior to assembly of your SOLAR BUG, we want you to understand Zener and FLED Engines as it is a part of your kit. The purpose is to make you solder these engines on separate PCBs as a practice before the actual assembly of your BUG. Working: 1) As light falls on the solar cell and the capacitor charges with respect to time and

the voltage starts increasing across the capacitor. 2) Initially all the transistors are off (no current in the circuit) . 3) As both the transistors are off the only path remaining for the voltage to appear is

through motor, 2.2K resistor and zener diode. 4) Zener diode used has a 2.7V zener voltage, which means it will conduct in

reverse bias after crossing 2.7V at cathode.

2.2KΩ

2.7V Zener Diode

2N3906

2N3904

M

+

_

1000

µF

Solar Cell

+

_

Zener Engine

R Q1

Q2

TRANSISTORS

Q1-PNP

Q2-NPN

C1

Note : For working of zener diode and transistors please refer page no. 48

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SOLAR BUG


6) As the voltage of capacitor reaches 2.7V i.e. the same voltage required to

conduct zener in reverse, will start conducting. 7) As zener is ON ,the PNP (2N3906) transistor will get a base drive (signal) and

will turn on. 8) Now the PNP transistor turns ON the NPN transistor because they are

connected in positive feedback loop. 9) As both the transistors get into saturation region (ON state) the circuit completes

and the motor starts running and capacitor starts discharging. 10) If you have noticed the main aim of the zener diode was to trigger at 2.7V and

after that it hardly plays any role. 11) After triggering the circuit at 2.7V both the transistors are turned ON and they

remain ON till 0.7V (minimum voltage required to conduct transistor). As both the transistors are connected in positive feedback loop the PNP will keep the NPN ON and the NPN will keep the PNP ON (Both the transistors are turned OFF below 0.7V ).

12) As soon as the voltage across capacitor goes below 0.7V the circuit gets off, the motor stops and the capacitor starts charging again.

13) Thus the charging and the discharging cycle continue. 2. FLED Engine:

Solar C

ell

Note; FLED stands for FLASHING LED

+

_

+

_

2.2KΩ

2N3904

2N3906 1000µF

M

FLED

FLED Engine

Q1

Q2

C1

R

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SOLAR BUG


If you can observe the FLED engine it is similar to zener engine the only difference is that we have replaced zener with FLED having cut off voltage of 2.4 volts. So the working of the FLED engine remains the same except it will trigger the circuit at 2.4V and the cycle will continue as discussed in Zener.

3. Miller Engine:

This circuit makes use of the IC1381. It exhibits the property of HYSTERISIS. It is the property of the IC which is same as positive feedback that we intend to use in the circuit. The working of this circuit is as follows-

• As light falls on the solar panel the larger capacitor C1 starts charging and the voltage starts developing across the capacitor.

• If you can see the circuit, the larger capacitor is in parallel with the smaller capacitor of C2(0.22μf) and the germanium diode is in series with the smaller capacitor C2.

• Once voltage across larger capacitor C1 exceeds 0.3V (minimum voltage required to conducts the diode conducts and completes the path for the current to flow, because of which the smaller capacitor C2 also starts charging.

Sol

ar P

anel

1381

2

C2

M

+

_

+

_ C1

3

1 Q1 NPN 2.2K

Motor

R

D1

Miller Engine

Note : Unlike zener, FLED will conduct in forward bias. The cut off voltage for FLED is 2.4V. For more details about zener and FLED refer page no. 48

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SOLAR BUG


• Thus we can conclude that the voltage developed across the smaller capacitor

C2 will always be lagging by 0.3V from larger capacitor C1.

• Since we are using IC1381 of Q series which has two trigger voltage levels

Voff =3.8V and Von=4.1V, these two voltage levels decide ON and OFF operation

of IC 1381.

For example, IC1381Q will turn on at 4.1V and will turn off below 3.8V,

but one should remember that 1381 has hysteresis. That means the

operating region of 1381 is between 4.1 and 3.8V giving us a hysteresis

of 0.3V.

Have a look at the block diagram----

Sol

ar p

anel

M

+

_

+

_ C1

Motor

R 2

3

1

D1

Q1 NPN 2N3904

C2 1381

4.4V

4.1V

0.3V 0V

Let’s see the working of miller engine in detail:

• As light falls on solar panel, voltage is developing across the larger capacitor with respect to time.

Vol

tage

acr

oss

capa

cito

r

Time

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SOLAR BUG


• Voltage across larger capacitor will reach 4.4V,at that time voltage across

smaller capacitor would be 4.1V(0.3V lag due to germanium diode) which is the

turn ON voltage for IC 1381.

• As 1381 turns ON it gives base drive (signal) to NPN transistor and it turns ON

causing the current to flow through it and the Motor starts running.

• Since the Motor is running the voltage across larger capacitor C1 starts

reducing, which in turn reduces the voltage across smaller capacitor C2.

• As voltage across larger capacitor reaches 4.1V(that is 3.8V across smaller

capacitor C2) turns OFF and the larger capacitor starts charging again.

• The point to note is larger capacitor discharges through motor while the smaller

capacitor discharges through the internal impedance of IC1381.

• The smaller capacitor does not have any other path to discharge as the

germanium diode gets reversed bias in the path to discharge.

• As smaller capacitor discharges through internal impedance of IC1381 which is

very high, the smaller capacitor will discharge very slowly ultimately maintaining

the voltage across it, thus causing the motor to run for longer time.

• Thus we can say that because of the arrangement of the smaller capacitor and

diode in the MILLER CIRCUIT provides longer bursts causing the motor to run

and avoids the larger capacitor to discharge completely!!!!!!

22

SOLAR BUG


SOLAR BUG CIRCUIT :

• The circuit of SOLAR BUG consists of two Miller Engines connected to each other

through a variable Resistor at pin 2 of IC1381.

• Solar panel and capacitor C1 is in parallel to both the miller engines.

• As the light falls on the solar panel larger capacitor is charging with respect to

time.

• It is the property of the solar sensor that the resistance of the solar sensor

increases in proportion with the increase in the incident light.

• Now suppose light is incident on the solar sensor on the right hand side (Miller 2).

Sol

ar p

anel

2N3904

+

_

Solar Sensor

Solar Sensor

1000uF/

C1

1

1N4148

0.22μF 0.22μF

Tactile sensor

Tactile sensor

2N3904

Trimpot 100K

1381 1381

M M

1N4148

2

3

1 2

3

C2 C3

Q1 Q2

D1 D2

Miller 1 Miller 2

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SOLAR BUG


• As the current always takes low resistance path, the current will not flow through the

path having high resistance (Miller 2), rather it would take an alternate path which has

low resistance (Miller 1) and it will start charging the 0.22μf capacitor as shown in the

diagram below.

• When the larger capacitor ‘C1’ is being charged in either condition, it would wait

until a triggering voltage for the IC 1381-Q is achieved.

• As soon as that particular voltage is received at that node [ junction of capacitor

and IC 1381 ], it would trigger the transistor which would take the transistor to

the saturation point and allow the current to flow through it.

• That means the current would take its path through the motor and the motor

would run!!!!

2N3904

+

_

Solar Sensor

Solar Sensor

1000μF/16V

C1

1

1N4148

0.22μF 0.22μF

Tactile sensor

Tactile sensor

2N3904

Trimpot 100K

1381 1381

M M

1N4148

2

3

1 2

3

Current direction

Sol

ar p

anel

Q1 Q2

C3 C2

D1 D2

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SOLAR BUG


So, if you may have noticed, if the light is incident on the right solar sensor then the motor which is on the left hand side would start running and vice versa. Hence the SOLAR BUG would crawl towards light as shown below.

Light Source

Solar Bug following

Zig - Zag Pattern

LIGHT LIGHT

Note: The bug will only work under yellow light because the emission of photons is more in yellow light as compared to white light.

You can use bulb of 200Wor 500W, halogen or sunlight.

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SOLAR BUG


The most important skill

needed to successfully construct

your Robot is soldering.

Do you know how to do soldering??

If your answer is “NO” then

must read next few instructions (in

fact all of it !!) and if your answer is

”Yes” then also just take a look at

the following instructions as it will

just take few minutes. Make sure

you start by using electronics solder,

not plumber’s solder!!

First a few safety precautions:

• Never touch the element or tip of the soldering iron.

They are very hot (about 400°C) and will give you a nasty burn

• Take great care to avoid touching the mains Power Cord with the tip of the iron.

The iron should have a heatproof cord for extra protection. An ordinary power cord will melt immediately if touched by a hot iron and there is a serious risk of burns and electric shock.

• Always return the soldering iron to its stand when not in use.

Never put it down on your workbench, even for a moment!

• Work in a well-ventilated area.

The smoke formed as you melt solder is mostly from the flux and quite irritating. Avoid breathing it by keeping your head to the side of, not above, your work.

• Wash your hands after using solder

• Always do the soldering under observation

of adults.

Soldering Tips

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SOLAR BUG


Preparing the soldering iron: (please refer the diag. on next page). • Place the soldering iron in its stand

and plug in.

Iron will take a few minutes to reach its operating temperature of about 400°C.

• Dampen the sponge in the stand.

The best way to do this is to lift it out the stand and hold it under a cold tap for a moment, then squeeze to remove excess water. It should be damp, not dripping wet.

• Wait a few minutes for the soldering iron to warm up.

You can check if it is ready by trying to melt a little solder on the tip.

• Wipe the tip of the iron on the damp sponge.

This will clean the tip.

• Melt a little solder on the tip of the iron.

This is to ensure the heat to flow from the iron's tip to the joint. It only needs to be done when you plug in the iron.

You are now ready to start soldering:

• Use table for soldering .

• Hold the soldering iron like a pen, near the base of the handle.

imagine you are going to write your name! Remember to never touch the hot element or tip.

• Touch the soldering iron onto the joint to be made.

Make sure it touches both the component lead and the track. Hold the tip there for a few seconds and...

• Feed a little solder onto the joint.

It should flow smoothly onto the lead and track to form a volcano shape as shown in the diagram. Apply the solder to the joint, not the iron.

• Remove the solder, then the iron, while keeping the joint still.

Allow the joint a few seconds to cool before you move the circuit board.

Which soldering kit should you buy???? The best you can buy from the market are SOLDRON, TONY and MAXGOLD irons.

27

SOLAR BUG


Assemble the proper tools

1. Cutter 2. Soldering iron 3. Soldering wire 4. Soldering iron stand

Mount component by bending leads out slightly so that they do not fall out.

Heat iron. Clean tip with damp sponge.

Apply heat. Apply solder within 5sec of time.

Remove solder. Remove iron. Hold component in

position till solder solidifies.

Inspect solder. Cut lead

Soldering Technique

28

SOLAR BUG


Note:

Before you start soldering on main board, we recommend you to do some practice on general purpose PCB by soldering the Zener and FLED engine on it.

And when you are confident enough on your soldering skills, you can proceed with machine development.

GOOD JOINT BAD JOINT

shiny solder

dull solder

Component lead

PCB or Strip board

Component

copper tracks

(volcano shape) (Dry joint)

Note : While soldering do not apply excessive heat as it might damage component as well as tracks.

29

SOLAR BUG


Zener and FLED Engines are basic circuits in BEAM Robotics , so before starting the assembly of your Solar Bug lets do some soldering practice on General purpose board which is given to you as part of the kit.

General Purpose Board

The general purpose PCB has soldering PAD, Zener and FLED engine embossed on it.

Soldering PAD’s are provided to practice soldering of different electronic components while zener and FLED engines are provided for testing purpose.

Soldering pad

Zener Engine FLED Engine

30

SOLAR BUG


Bend the resistor appropriately

Soldering Pad: On soldering pad you can practice soldering different electronic compo-nents like resistors, IC’s, transistors, capacitors and many such components.

Note: for soldering practice do not use the components which are provided to you in the kit, as they are for testing zener and FLED engines. For practicing you can use scrap components or purchase components from the market.

Before soldering one has to take care of the placement of components on the PCB, for example while soldering resistor, it has to be bent first for the proper placement on the PCB as shown in the fig below.

In the fig. below you will see that a resistor is inserted in to any two holes from the top side of the PCB and it is soldered from the bottom side of the PCB

Insert the resistor from the top side of the PCB

Solder the resistor from the bottom side of the PCB

31

SOLAR BUG


This is how it should be soldered…..

After soldering cut the leads of the components with the help of a cutter as shown below.

Similarly you can practice soldering different components on the PCB and then you can go forward and start soldering the zener and FLED engine using the components provided to you in the kit.

32

SOLAR BUG


Now Let’s start soldering the zener engine!!!!!!!!

Zener and FLED engines are embossed separately on the general purpose board with different tracks for supply (VCC) and Ground (GND).

Note: In case of soldering any circuit always start with smaller components, so that it be-comes easier for us to solder the entire circuit.

Zener Engine:

Step 1: Solder 2.2KΩ resistor at R1.

Separate tracks of VCC and GND for Zener engine

Separate tracks of VCC and GND for FLED engine

VCC GND

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SOLAR BUG


Step 2: Solder NPN transistor 3904 in the appropriate slot on the PCB as shown below.

Similarly solder PNP transistor 3906 in the appropriate slot on the PCB.

Note: Before soldering the transistors please see the numbers printed on them.

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SOLAR BUG


Step 3: Solder Zener Diode as per the symbol printed on the PCB.

While soldering Zener diode see that the black strip on the diode matches with the white strip of the diode symbol on the PCB.

The fig. below shows the actual position of Zener diode on the PCB.

Diode Symbol with white strip

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SOLAR BUG


Step 4: Solder 1000μF capacitor at C1 as shown below.

Note: while soldering capacitor make sure that you solder it according to the polarities mentioned on the PCB, the longest lead of the capacitor is positive and the shortest lead is negative.

Step 5: Now solder motor, as motor does not have polarities you can solder it di-rectly on the PCB as shown below.

Note: Before soldering motor on the board, its wires has to be tinned for proper solder-ing on the PCB.

For tinning, melt the solder-ing metal with the tip of the soldering iron and apply the melted metal on the wires as

shown in the fig.

Solder the two wires of motor in to the slot provided on the PCB

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SOLAR BUG


Step 6: Finally solder the solar panel to VCC and ground.

Note: While soldering the solar panel make sure that you solder it according to the po-larities mentioned on the panel as well as on the PCB. The red wire of solar panel should be connected to the VCC and the black wire of solar panel should be con-nected to ground (GND).

Once this is done, all you need to do is focus light on the solar panel and your motor should run…..

Step 7:Similarly you can solder all the components of FLED engine on the FLED section of the PCB. While soldering FLED see to that you are soldering it as per the polarities of the FLED.

In case of FLED make sure that you solder it accord-ing to the symbol printed on the PCB.

The FLED should be soldered in such a way that the cut on the FLED matches with the cut on the symbol as shown in the fig.

The cut on the symbol for FLED

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SOLAR BUG


Step 8: After soldering FLED engine you can now test it by connecting solar panel to the VCC and GND.

Note: In case of Zener and FLED engine only one motor is provided to you for testing, so after soldering both the engines you can test them one at a time by simply de-soldering the motor and solar panel and connecting them to the other engine for testing.

In this fig. you can see, the cut on the FLED is matching with the cut of the symbol printed on the PCB.

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SOLAR BUG


Mounting of 2N3904 transistors: 1

Before you start Mounting Components on Your PCB observe it carefully. On keen observation you will notice that the position of each component is clearly embossed on the PCB itself.

Let’s first mount the 2N3904 NPN Transistors. The transistors, when observed from top, you will notice that it has one surface curved and one flat. Place those transistors according to the surface cut indicated on the PCB. Carefully solder it. Make sure that you don’t melt the PCB, but the solder metal!

Tools Required :

• All the components of solar bug

• Soldering iron (not included)

• Soldering wire (not included)

• Pliers (not included)

• Cutter (not included)

Step

Emitter

Base Collector

Note :While soldering make sure all the components are soldered as close to the PCB as possible, because components would be facing ground when the machine is working.

Robot Assembly

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SOLAR BUG


Mounting of TRIM Pot: 2

Now we will solder the trim pot. To mount the trim pot, place the pot in such a way that tuning screw on the pot is mounted exactly in the same way as shown in the figure.

Tuning Screw

Bend Pins of Trim POT in this manner

After Bending the pins mount the pot on the PCB as show below.

Step

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SOLAR BUG


Mounting of 1381 IC: 4

Mounting of 1N4148 DIODES: 3

Mount the diodes in such a way that black circle on diode (cathode or

negative terminal) coincides with inscription on the PCB or the black ring should

be towards the front side of Bug .

The black ring indicates Cathode

Note: This is how it will look after mounting all the above components.

Now place the IC 1381 in the same manner as the transistors are placed.

Just be careful with the cut face and the curved face embossed on the PCB.

Note: Make sure you solder 1381 IC properly because it might get damage due to excessive heat and may cost you a lot.

Step

Step

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SOLAR BUG


Mounting of Solar sensor : 6

Mounting of SMALL CERAMIC CAPACITORS: 5

Solder 0.22μF capacitor. The capacitor that you are using is ceramic capacitor so there is no issue of polarity that comes into picture. The value of these capacitors should be small in comparison to the larger capacitor

[please refer the working of the miller circuit]

Now place the solar sensor IC in the same manner as the transistors are placed. Just be careful with the cut face and the curved face once again

0.22 μF Capacitor

Step

Step

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SOLAR BUG


Mounting of Motor Mounts : 8

Mounting of Big Capacitor : 7

Solder the larger capacitor [1000μF]. Here polarity comes into picture.

Longer lead of the capacitor is anode [+ve] and shorter one is cathode [-ve] termi-

nal. Match the polarity of capacitor as per printed on the PCB

After completing all these steps, just turn over the PCB and mount the motor mounts

on PCB as shown below.

Note: make sure that you solder the motor mounts firmly on the PCB.

Step

Step

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SOLAR BUG


Support Wires : 9

Before we proceed further with installation of motors we first need to

support the arms of the SOLAR BUG with the help of Support Wire which is

needed to hold the motors in an inclined manner across the surface, so that shaft

of the motor comes in contact with the ground.

Our BUG will crawl only when the shaft touches the ground otherwise

the motor will run but your BUG will not crawl!!!

This is how it should look after mounting the above components, Hope you

are having great fun doing this!!!!!!!!!!!!

Step

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SOLAR BUG


Mounting Motors : 10

Now mount the motors on motor mount such that motors should be inclined to the surface. While soldering the wires of motors just see to it that blue and red wires of the motor are soldered accordingly. You can see that a single motor has 2 wires blue and red that has to be soldered to M-blue and M-Red mentioned on the PCB.

Note: This is how the motors need to be soldered with the inclination as depicted in the picture.

Step

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SOLAR BUG


Now take a small piece of heat shrink tubing ,slide it on motor shaft. Shrink the

tube by applying heat with soldering iron so that it firmly grips the motor shaft.

Heat shrink tubing is required for traction between ground and motor shaft.

Note: The shaft of the Motor is 8mm long so cut the heat shrink tube according to

the length of the shaft and don't insert the tube entirely on the shaft.

Next we will mount the power source for our BUG that is nothing but the

SOLAR PANEL. If you observe the solar panel thoroughly you will see that the

positive and negative terminals of the solar panel is imprinted on the backside of

the panel, also you can see that the positive and negative polarities are itched

on the PCB .So just connect the terminals accordingly and the power source is

now ready to suffice the current and voltage requirements of the SOLAR BUG.

Note: while soldering solar panel make sure that +ve terminal of the solar

panel should be connected to the +ve of capacitor and –ve should be

connected to the –ve of capacitor (parallel connection).

Mounting Heat shrink on Motor shaft: 11

Step

Mounting of Solar Panel: 12

Step

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SOLAR BUG


Solar cell polarities Top view of Solar

cell polarities

Past Double Sided Tape on the back side of the solar

panel

Solder the solar panel as shown

above

!! Motor and solar panel will be soldered on the upper side of PCB.

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SOLAR BUG


Let your BUG crawl first time : 13

Before you start testing your Solar Bug let me tell you one thing that

the solar panel we are using is polycrystalline solar panel. It delivers 6.7 V

and 33mA current. Just make sure you are not using florescent lamps

(Metal High Lights) to test your machine. Use normal yellow light (halogen

500W ) or you can use 200W bulb, if halogen is not available to you.( You

can get it from local hardware shop).

Now check whether your machine is moving towards light? If its then

good and if it is just moving on single motor then fine tune the POT for

adjusting sensor sensitivity.

If only one of the motor is running then what you need to do is, you

have to turn the screw of the TRIM POT towards the running motor and you

have to continue this until a point where both the motors start running.

Step

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SOLAR BUG


How does TACTILE SENSOR WORK!!!!!

First of all the berg strips, heat shrink tubing, and the whiskers collectively form the TACTILE SENSOR. The tactile sensors are simple switches. When the spring around the berg strip bends, it touches the strip on the inside, activating the touch-detection circuit.

The whiskers when come in contact with the obstacle gets stretched and touches

the exposed part of the berg strip, thus bypassing the solar sensor and avoids the

obstacle.

For example in our solar bug circuit if light is falling on one side (miller 1) then the

opposite side (miller 2) will be activated and vice versa.

After mounting the tactile sensor if the light falls on one side (miller1) of the circuit

and if obstacle is detected then only that particular side (miller 1) of the circuit will

be activated and the other side will be OFF, this is because the tactile sensor will

act as a switch and will bypass the solar sensor when the switch is shorted

(obstacle detected).

How to make your Bug More Sensitive to Obstacles!!!

This is achieved simply by maintaining the length of the heat shrink tub-ing on the berg strip. Longer the tubing on the berg strip lesser the sensitivity because the whiskers will get less point of contact when stretched due to ob-stacle. And if the tubing is smaller then whiskers will get large point of contact when stretched due to obstacle.

This is simple isn’t it!!!

Note: The bug can even run independently without mounting tactile sensors

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SOLAR BUG


Mounting Tactile Sensor : 14

The addition of tactile sensor on

your bug will give it an Obstacle Avoidance feature.

2. Now mount the heat shrink on

the berg strips with the help of

soldering iron. To do this hold the

berg strip with the help of pliers

and heat the tubing until it snug’s

down to the strip .(do this on both

the berg strips).

1. For mounting the TACTILE

SENSOR first you need to cut the

berg strip into two pieces as

shown below.

Berg Strips

Berg Strip and heat shrink.

Pliers holding the Berg strip

3. Now solder these berg strips on

the large solder PAD’S given on

the PCB.

4. Now mount the whiskers on

both the berg strips in such a

way that it gives moustaches

like looks to your bug.

This is how it should be soldered on the solder

pads

Note: whiskers are noth-ing but the spring

Do not remove plastic casing

Step

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SOLAR BUG


That’s it!!! Now your bug is ready to follow the Light on its own and if something comes in between, it will avoid it!!!

Remember the whiskers should be mounted in such a way that it covers the

berg strip and the small end of the whiskers should be soldered on the small hole

provided on the PCB as shown below.

These are the holes where you have to solder the smaller ends of the whiskers after inserting

it through the hole.

You have to make sure that the berg strip in the middle of the spring is right

in the middle. The best way to do this is to bend the spring at the base of the strip

and try to force it up/down/left/right until its right in the middle as shown below.

Good Bad

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SOLAR BUG


How to bend your tactile sensor!!!!!! After mounting the tactile sensor you have to bend the whiskers in a way that it looks like moustaches. A special care should be taken while bending the sensor, because if you bend it the wrong way it might damage or loose its orientation.

So you have to bend it in such a way that the whiskers should not touch the ground and it should remain suspended in air.

This is how you have to bend it with the help of pliers, making a 90° angle with the berg strip.

Bend both the whiskers as shown above

Note: For giving moustaches like shape to your whiskers you can bend the long part of whiskers with the hands as shown above.

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SOLAR BUG


Hopefully you won't need this section, but if you do, here a few checks and

tests to perform if you are SOLAR BUG is acting up. Above all else, make sure

that there are no solder-bridges. This is when solder crosses from one pad to the

next - a condition that should never be allowed to happen. It can also happen if

you don’t clip the extra leads or wires from underneath the component you

soldered it. The extra lead can touch and short out against other parts. Frayed

wires can also be at fault if a strand or two didn’t get soldered into the hole.

CONDITION 1:

If only one of the motor is running then what you need to do is, you have to turn

the screw of the TRIM POT towards the running motor and you have to continue

this until a point where both of the motor starts running.

CONDITION 2:

If one of the motor or both the motors are running in the opposite direction i.e. if

your SOLAR BUG which should move towards the light is moving away from the

light then you just need to de-solder the wires of the motor or motors and just

switch the positions of the wires and solder it again.

Troubleshooting

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SOLAR BUG


Finally your Machine should work like this

Sensing the Shadow, the Solar Bug skirts it on it's way to the brightest source of light available

Hitting the wall disables the opposite side's motor until the sensor comes free

Caution: while using the Bulb or Halogen to run your bug please make sure that you don't focus them on your face as it might damage your eyes. To avoid this accident make use of safety glasses.

This Solar Bug has the light dead in it's sights, and makes a left / right / left / right motion to get to it.

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SOLAR BUG


No movement / action:

This can be attributed to many factors. If you have a multimeter, try the tests in the brackets ().

- Solar cell hooked up backwards? (Voltage positive on pad marked "+")

- Power capacitor hooked up backwards? (Voltage climbs only to 1.5-2 volts)

- Motors hooked up to pads "M-Blue" & "M-Red"?

- Trim pot installed?

- Transistors in correct place and orientation?

- 1381 in correct place and orientation?

- Diode in correct place and orientation?

- Motor touching ground?

If you find you’re having more problems with your Solar Bug than you can con-

tact us for more assistance. To make this procedure simpler, just do one thing i.e.

take photographs of your solar bug and email us on our email id with whatever prob-

lem you’re facing. Our technical support team will happy to answer your queries.

You can mail your problem on [email protected]

or visit forum section of our website.

Only one side works:

When only one side works, you can compare it against the side that is working.

Check and compare these conditions:

- Motor hooked up to pads "M-Blue" & "M-Red"?

- Trim pot adjustment turned all the way over to one side?

- There’s a bridge across the sensor pin pad to the spring pad

- The connection pads on the solar cell may be touching a part of the circuit

board below it

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SOLAR BUG


Falling voltage across C

DISCHARGE CHARGE

Time

Rising voltage across C

Volts

The main power source of our robot is SOLAR PANEL. Light absorption capacity of solar panel depends on the dimension of solar cell i.e. Larger surface area will have higher absorption capacity and hence output will be higher.

As our robot is solar based we have to store this energy into some storing element such as ca-pacitor or condenser. Larger the value of capacitance more amount of energy would be stored.

When capacitors are connected in series, the total capacitance is less than any one of the series capacitor’s individual capacitances.

Series capacitance:

When capacitors are connected in parallel, the total capacitance is the sum of the individual capacitor’s capacitances.

Parallel capacitance:

Capacitors charging and discharging time:

Charging time of capacitor depends on the capacitance of capacitor. i.e. 1F capacitor will have more charging time as compared to 1000uF capacitor.

Discharging time of capacitor depends

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SOLAR BUG


Transistors:

In any electronic circuit transistors are commonly used as amplifier or switch. In our project we are using transistor as a switch.

There are two types of BJT (bipolar junction transistor):-PNP and NPN.

PNP NPN

Symbols

Base drive is required to turn on the any transistor. But the direction of current is different in PNP and NPN.

In NPN transistor current flows in to the base while in PNP transistor current flows out of the base.

In above symbol the arrow at emitter denotes the direction of current.

In PNP transistor current flow from emitter to collector, while in NPN transistor current flow form collector to emitter. IC 1381:

IC 1381 is a CMOS voltage controlled trigger IC. It has two trigger voltage levels: ON and OFF.

In our project it is used to determine when the solar engine should "fire”.

2 1

3

These IC’s are discriminated by the voltage at which the 1381 triggers, with a single-digit suffix (a.k.a., its "rank") on the part number corresponding to the trip voltage.

It has 3 pins. In OFF state pin no. 3 is connected to pin no. 1 and in ON state pin no.2 is connected to pin no.1 internally.

Diodes:

Anode Cathode

Diode is a two terminal device. The most common function of a diode is to allow an electric current in one direction (called the forward biased condition) and to block the current in the opposite direction (the reverse biased condition).

Choice of diode in the circuit depends on its current and voltage ratings.

Here, in our project we are using Germanium diode (breakdown voltage 0.3V).

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SOLAR BUG


Motor :

We are using 3V pager motor of 8mm shaft. These motors come in handy for small projects like ours because it is compact, very efficient, consumes less current and gives excellent output.

Zener Diode:

A Zener Diode is a special kind of diode which permits current to flow in forward direction as well as in reverse direction when the voltage is above a certain value that is the breakdown voltage known as the Zener voltage .

Zener diode is available with various zener voltages starting from 2.4V to 210V. In our project we are using Zener of 2.7 volts.

FLED:

FLED stands for Flashing Light Emitting Diode. This is a very special kind of diode, which produces light and always conducts in forward bias. The FLED’S are similar to normal LED’S but the only difference is that LED emit’s light continuously while FLED flashes light continuously out of it and the flashing of FLED indicates that the current is flowing through it.

Note: Please do not confuse between conventional diode and zener diode as they look similar. Make use of magnifying glass to identify the diodes according to the information imprinted on them.

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SOLAR BUG


Now let’s test our understanding...... Based on the concepts that were discussed in the previous section try to answer some of the following!!!!! 1. If light falls on solar cell and the

voltage rating of solar cell is 6.7V then what would be the output voltage of the solar panel???

2. Why we are not connecting motor directly to solar panel?

5. what is an engine?

4. Why we are not using silicon diode in place of germanium diode in miller engine?

3. For a transistor to work as a switch, transistor should op-erate in which two regions?

6. If i have two 1F capacitors, how should i connect them to achieve a capacitance of 2F?

For answers Try and Try till you cry and God forbid if you cry contact us at

[email protected]

Scratch Your Head

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SOLAR BUG


The Solar bug is a design that has a strong heritage in BEAM Robots competition, a very popular event in Techfest and Nexus. This competition is open to all, in which the bug has to avoid obstacles and has to reach the centre point of the game field first. The bug which achieves this in the least amount of time will be the winner of the competition.

Following is the problem statement for the competition:

Construct an automated light seeking robot which uses solar power as the only source of energy and is capable of avoiding obstacles. The robot should reach the center of the game field avoiding all the obstacles in its way. Halogen light would be used as the source of energy which would be focused from the top on the game field.

Game Field Specifications: The game field is a white flat surface having an area of 620x620mm. It has 80mm tall obstacles mounted on the game field with a large circle of diameter 37mm in the centre. At the corners of the game field there are four squares of 150mm sides from where the competition starts.

Activity

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SOLAR BUG


This is Something interesting isn't it ??

So friends, as you have constructed a light seeking robot, you can also participate in competitions like this or simply prepare a game field of your own and you can have a competition amongst your friends. If you need any more components you can always order form our Roboshop on our website.

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SOLAR BUG


A-61, 1 st Floor, Raj Industrial Complex, Military Road, Marol,

Andheri (East), Mumbai – 400059

India Contact Information

Office: (91-22) 66751507 Office: (91-22) 66751507 Mobile: (91) 9930776661

Email: [email protected]

Visit us at


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AUTONOMOUS LIGHT SEEKING ROBOT - Robosoft Systems

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