Line Follower Robot

ABSTRACT

 

The present study aims at developing a LINE FOLLOWER ROBOT or a LINE TRACING ROBOT using Transistor. This Robot follows the black line which is drawn over the white surface or it follows the white line which is drawn over the black surface. The infrared sensors are used to sense the line. When the infrared signal falls on the white surface, it gets reflected and if it falls on the black surface, it is not reflected. This principle is used to scan the Lines for the Robot. All the above systems are controlled by the Transistors. In our project we are using mainly two transistors 2N2222 and TIP 122. The relay’s are used to control the motors. Transistor gets the signals from the infrared sensors and it drives the motors according to the sensor inputs. Two DC geared motors are used to drive the robot in forward, left or right direction.

Purpose & Overview of this project

           The purpose of this project is to build a device that can sense the difference between black and white color so that the robot can follow a black line on a sheet of white paper.           The robot will be low cost and completely made without any microcontroller. It will also be able to follow straight and curvy lines alike.

Analog Brains           The 2N2222 and TIP122 transistors are both of the NPN type. As you will see in the schematic portion of this project write-up, these transistors are used to decide what to do when the sensors see black or white. The TIP122 transistors are high-power which makes them perfect for running the motors.

Block Diagram

9V Battery is used as Dc power source. There are IR Transmitter An Receiver These two components combined with a few resistors will tell the circuit whether black or white is currently sensed. If white is sensed a 0.7-1.0 Volt signal is sent to the analog brains. If black is sensed, 0 Volts is sent. The IR Emitter (Transmitter) send outs IR light and the Phototransistor (IR receiver) receives IR light from the reflected surface we know that white will reflect all colors while black will absorb them. So when the LED emits IR onto white, the Phototransistor is turned on and sends a voltage signal to Q2. When light is reflected off of black color the Phototransistor is then turned off and no signal is sent. Switching Transistors switches either ON or OFF according to their base voltage. Motor driver Drives the motor.

9V Battery

IR Transmitter

IR Receiver Switching Transistors

Motor Driver

Motor1

Motor2

Circuit Diagram

This circuit combines the Motor circuit and the IR Sensor Circuit. Using 2 2N2222's, 1 TIP 122 and some resistors a circuit is built that interprets the two cases. When white color is detected Q2 is turned on, which turns off Q1and Q3 on and the motor 1 will rotate. In the opposite case, when black color is detected Q2 is turned off, which means Q1 remains on and Q3 off and the motors2 will rotate. This happens in one of two cases. When black color is sensed, the circuit switches Q2 and Q3off and Q1 on. When white color is sensed the case is reversed with Q2 and Q3 on and Q1 off. This means the motors are never actually on at the same time and the illusion of driving forward is created by quick back-and-forth movements .

Hardware description

Plastic Infrared Emitting Diode

Features:• Choice of narrow or wide irradiance pattern• Choice of power ranges• Choice of T-1¾, TO-18 or T-46 package• Higher power output than GaAs at equivalent LEDs

Each device in this series, is a gallium aluminum arsenide infrared Light Emitting Diode (LED) that is molded in anIR-transmissive package with a wavelength centered at 890 nm, which closely matches the spectral response ofsilicon phototransistors, except for OP298 (AA, AB, AC, AD), which has an 875 nm wavelength. For identificationpurposes, each LED anode lead is longer than the cathode lead. Package T-1¾ devices include: OP290,OP291, OP292, OP294, OP295, OP296, OP297, OP299 (A, B, C). Plastic Package TO-18 or TO-46 devicesinclude: OP293 and OP298 (A, B, C, AA, AB, AC, AD).Each OP290, OP291 and OP292 series come in three electrical parameters options A, B and C. The OP290series forward current is specified under pulse conditions up to 1.5 amps, the OP291 series forward current isspecified under pulse conditions up to 100 milliamps and the OP292 series forward current is specified under

pulse conditions up to 1 amp. The Cathode Lead length is 0.06” (1.52 mm) shorter than the Anode Lead. The silver-copper lead frame offers excellent thermal characteristics. Each OP293 and OP298 series come in three electrical parameter options A, B and C. The OP293 series has an included emission angle of 60° while the OP298 series has an included emission angle of 25°. The Cathode Lead length is 0.06” (1.52 mm) shorter than the Anode Lead. These devices, which come in a variety of power ranges offering a low cost replacement for TO-18 or TO-46 hermetic packages. Each OP298 series come with a high irradiance output versions with four electrical parameter options AA, AB, AC and AD. These power options are in the range of 5X greater than the A, B or C options. The OP298 series has an included emission angle of 25°. The Cathode Lead length is 0.06” (1.52 mm) shorter than the Anode Lead. These devices, which come in a variety of power ranges offering a low cost replacement for TO-18 or TO-46 hermeticpackages.OP294 and OP299 are designed for low-current or power-limited applications, such as battery supplies. They are similar to the OP290 and OP295, but use a smaller chip that increases output efficiency at low current levels by increasing current density. Light output can be maximized with continuous (D.C.) forward current up to 100 mA or with pulsed forward current up to 750 mA. The Cathode Lead length is 0.06” (1.52 mm) shorter than the Anode Lead. Each OP295, OP296 and OP297 series come in three electrical parameters options A, B and C. The OP295 series forward current is specified under pulse conditions up to 5 amps, the OP296 series forward current is specified under pulse conditions up to 2 amps and the OP297 series forward current is specified under pulse conditions up to 1 amp. The Cathode Lead length is 0.06” (1.52 mm) shorter than the Anode Lead. The silver copper lead frame offers excellent thermal characteristics. These devices are UL recognized, File No. S2047. All of these devices are spectrally and mechanically matched to the OP593 and OP598 series phototransistors.Please refer to Application Bulletins 208 and 210 for additional design information and reliability (degradation) data.

Applications: Machine safety End of travel sensor Non-contact reflective object sensor Assembly line automation Door sensor Battery-operated applications

NPN Plastic Silicon Phototransistors

Fea turesVariety of sensitivity rangesT-1 3/4 package styleDe scrip tionThe OP599 series phototransistor consists of an NPN silicon phototransistor mounted in a dark blue plastic injection molded shell package. The narrow receiving angle provides excellent on-axis coupling. The sensors are 100% production tested for close correlation with Optek Ga Al As emitters. Optek’s packaging process provides excellent optical and mechanical axis alignment. The shell also provides excellent optical lens surface, control of chip placement, and consistency of theoutside package dimensions.

Ab so lute Maxi mum Rat ings (TA = 25o C un less oth er wise noted)Collector- Emitter Volt age. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 VEmitter- Collector Volt age . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.0 VContinuous Col lector Cur rent . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50 mAStorage and Op erating Tem perature Range . . . . . . . . . . . . . . . . . . -40o C to +100o CLead Sol dering Tem perature (1/16 inch [1.6 mm] from case for 5 sec. withsoldering iron). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 260o C(1)Power Dis sipation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100 mW(2)Notes:(1) RMA flux is recommended. Duration can be extended to 10 sec. max. when flow soldering.Max. 20 grams force may be applied to leads when soldering.(2) Derate linearly 1.33 mW/o C above 25o C.(3) VCE = 5 V. Light source is an unfiltered GaAlAs emitting diode operating at peak emissionwavelength of 890 nm and Ee(APT) of .25 mW/cm2.(4) This dimension is held to within ± 0.005" on the flange edge and may vary up to ± 0.020" inthe area of the leads.

TIP 122Plastic Medium-Power Complementary Silicon Transistors

Designed for general-purpose amplifier and low-speed switchingapplications.Features

High DC Current Gain -hFE = 2500 (Typ) @ IC= 4.0 Adc

Collector-Emitter Sustaining Voltage - @ 100 mAdcVCEO(sus) = 60 Vdc (Min) - TIP120, TIP125= 80 Vdc (Min) - TIP121, TIP126= 100 Vdc (Min) - TIP122, TIP127

Low Collector-Emitter Saturation Voltage -VCE(sat) = 2.0 Vdc (Max) @ IC = 3.0 Adc= 4.0 Vdc (Max) @ IC = 5.0 Adc

Monolithic Construction with Built-In Base-Emitter Shunt Resistors Pb-Free Packages are Available

RW Relay

A relay is an electrically operated switch. Many relays use an electromagnet to operate a switching mechanism mechanically, but other operating principles are also used. Relays are used where it is necessary to control a circuit by a low-power signal (with complete electrical isolation

between control and controlled circuits), or where several circuits must be controlled by one signal.

Main Feature1. RW Series Relay covers switching capacity by 10A in spite of miniature size to comply

with user’s wide selection.2. RWH is approved C-UL & TÜV safety standard.3. The employment of suitable plastic materials is applied under high temperature

condition and various chemical solutions.4. Complete protective construction is designed from dust and soldering flux. If required,

plastic sealed type is available for washing procedure.5. 12A at 120VAC for RW & 12A at 240VAC for RWH are UL approved.6. Halogen Free series is available.

Specification

* Type of Sealing - Plastic Sealed Type * Number of Poles – Single Poles * SPST Telecom Relay * Coil Voltage - 5V * Coil Sensitivity - 0.20W * Rating: 10A at 120VAC / 10A at 24VDC

Performance (at Initial Value)

Contact Resistance ............. 100mΩ Max.@1A, 6VDC Operate Time.......................10 mSec. Max. Release Time ......................5 mSec. Max. Dielectric Strength Between Coil & Contact ...... 1,000VAC at 50/60 Hzfor one minute. Between Contacts ............... 500VAC at 50/60 Hz for one minute. Surge Strength .................... 3,000V (between Coil & Contact 1.2x50μSec.) Insulation Resistance .......... 100 MegaΩ Min. at500VDC. Max. On/Off Switching :Electrical.............................. 6 Cycles per Minute.Mechanical.......................... 300 Cycles per Minute.Temperature Range............. -30～85°CHumidity Range...................45～85% RH.Coil Temperature Rise.........35°C Max.Vibration :Endurance ........................... 10 to 55 Hz dualamplitude width 1.5mm.Error Operation.................... 10 to 55 Hz dualamplitude width 1.5mm.Shock :Endurance ......................... 1,000 m/S2.Error Operation.................... 100 m/S2.Life Expectancy :Mechanical .........................107 Operations at NoLoad condition.Electrical ..............................105 Operations at RatedResistive Load.Weight ................................. About 9 g.

ApplicationDomestic Appliances, Office Machines, Audio Equipment,Coffeepot, Control units, etc.

DC Gear Motor

10RPM 12V DC geared motors for robotics applications. Very easy to use and available in standard size. Nut and threads on shaft to easily connect and internal threaded shaft for easily connecting it to wheel.

Features

10RPM 12V DC motors with Gearbox 6mm shaft diameter with internal hole 125gm weight Same size motor available in various rpm 5kgcm torque No-load current = 60 mA(Max), Load current = 300 mA(Max)

PCB Layout

Soldering

Soldering is the process of joining metals by using lower melting point metal to

wet or alloy with the joined surfaces. Solder is the joining material. It melts below 427oC.

Soldered joints in electronic circuits will establish strong electrical connections between

component leads. The popularly used solders are alloys of tin and lead that melt below the

melting point of tin.

In order to make the surfaces accept the solder readily, the component terminals

should be cleaned chemically or by abrasion using blades or knives. This process is called

tinning. Zinc chloride or ammonium chloride separately or in combination are the most

commonly used fluxes. These are available in petroleum jelly as paste flux. A solder joint

can at first glance to be okay, but under close examination it could be a ‘Dry Joint’. A dry

joint is when either the circuit board or the leg of the component has not been properly

heated to allow the solder to flow between the surfaces freely. This creates an intermittent or

no electrical connection. This can also be caused by a lack of flux or if you reuse old solder.

Quite often, reheating a bad join will cure the problem but in a lot of cases, the old solder

will need to be removed and some new solder applied. The residues, which remain after the

soldering, may be washed out with more water, accompanied by brushing.

Soldering iron is the tool used to melt the solder and apply at the joints in the

circuit. It operates in 230V mains supply. The iron bit at the tip of it gets heated up within a

few minutes. 50W and 25W soldering irons are commonly used for soldering purposes.

Procedure

Make a layout of the circuit. Straighten and clean the component leads using blade or

knife. Apply a little flux on the leads. Take a little solder on soldering iron and apply the molten

solder on the leads. Mount the components on the PCB by bending the leads of the components

using nose-pliers. Apply flux on the joints and solder the joints. Soldering must be done in

minimum time to avoid dry soldering and heating up of components. Wash the residues using IP

and brush.