Line follower robot


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  • The IR LED emits a beam of IR and the surface below reflect the beam. When the sensors senses the beam it generates a voltage. This voltage depends on the amount of the light sense by the sensor. When the intensity is higher the generated voltage is higher and when the intensity is lower the generated voltage is lower.
  • It may use an electromechanical mechanism, or passive or active electronic components. Depending on the design, it may be used to regulate one or more AC or DC voltages.
  • LFR uses two motors to control rear wheels . It has 3-infrared sensors on the bottom for detection of black tracking tape. When the middle sensor detects the black color, this sensor output is given to the comparator LM324. The output of comparator compares this sensor output with a reference voltage and gives an output. The output of comparator will be low when it receives an input from the sensor.
  • Black colour is capable of absorbing the radiation and white colour or a bright colour reflects the radiation back. Here, 3 pairs of IR TX and Rx are used. The robot uses these IR sensors to sense the line and the arrangement is made such that sensors face the ground. The output from the sensors is an analog signal which depends on the amount of light reflected back and this analog signal is given to the comparator to produce 0s and 1s.
  • Robot direction is determined by what the robot “sees”If line is centered in front of robot, go forwardIf line is left of center, turn leftIf line is right of center, turn rightIf no line is detected, circle until line is found
  • APPLICATION :Industrial automated equipment carriers.Automated cars.Tour guides in museums and other similar applications.Deliver the mail within  the office buildingDeliver medications in a hospital.
  • Line follower robot

    1. 1. Name of Institution A project report on Line follower robot SUBMITTED BY: PRIYA HADA B.TECH ECE (SECTION –B) VTH SEM 1
    3. 3. INTRODUCTION Name of Institution • What is a line follower? Line follower is a machine that can follow a path. The path can be visible like a black line on a white surface (or vice-versa) or it can be invisible like a magnetic field. • What is the need to build a line follower? Sensing a line and maneuvering the robot to stay on course, while constantly correcting wrong moves using feedback mechanism forms a simple yet effective closed loop system.
    4. 4. AT89C51 Name of Institution 4
    5. 5. LM324 Name of Institution IC LM324 is a comparator IC. It is a MAIN BRAIN of line tracer. The Ports takes two voltage inputs at positive and negative pin respectively, compares them and gives a digital output in the form of logical HIGH or logical LOW. 5
    6. 6. Name IR Transmitter & Receiver of Institution • • IR TRANSMITTER ( EMITTING DIODE) The IR LED emitting infrared light is put on in the transmitting unit. IR or VISIBLE light is emitted from the emitter This emitted light strikes the surface and gets reflected back. If the surface is white, more intensity of light gets reflected and for black surface very less intensity of light is reflected. IR RECEIVER (PHOTODETECTOR) Used to detect the intensity of light reflected. The corresponding analog voltage is induced based on the intensity of reflected light, which further compared by comparator and output send as 0 or 1.
    7. 7. IC 7805 Name of Institution  A voltage regulator is an electrical regulator designed to automatically maintain a constant voltage level. It converts a positive voltage (7-29V) to +5 volts. Heat sink provided in the center to release heat generated due to drop across the IC.  Input voltage of about 5 to 18 V is given, Ground is 0 V and regulated output of +5V. 7
    8. 8. L293D (H-Bridge) Name of Institution • Motors are arranged in a fashion called H-Bridge. • H-Bridge-It is an electronic circuit which enables a voltage to be applied across a load in either direction. • It allows a circuit full control over a standard electric DC motor. That is, with an H-bridge, a microcontroller, logic chip, or remote control can electronically command the motor to go forward, reverse, brake, and coast.
    9. 9. WORKING PRINCIPLE Name of Institution The robot uses IR(infrared) sensors to sense the line. Output of the sensors is an analog signal which depends on the amount of light reflected back. This analog signal is given to the comparator to produce 0s and 1s which are then fed to the uC. Then microcontroller decides the position of robot in left or right direction.
    10. 10. WORKING PRINCIPLE Name of Institution When a sensor is on the black line it reads 0 and when it is on the bright surface it reads 1. When left sensor comes in white(for black line tracer) region then right motor stops while left motor continue to move so that right turn takes place and robot returns on white line. First sensor which is to the right will become low as that sensor will be facing the black line and the remaining sensors response will be high. i.e. the right wheel is held constant and the left wheel is made to move freely until the response from the middle sensor becomes low . When right sensor comes in white region then left motor stops while right motor continue to move so that left turn takes place and robot returns on white line.
    11. 11. WORKING PRINCIPLE( contd…) Name of Institution The middle sensor will always be on the line and as the line is black in color, it will not reflect the emitted radiation back and the response of the sensor will be low and the response of the remaining two sensors will be high as they will be on the bright surface. When both sensors are on black line then robot moves forward. If all the three sensors will be on brighter surface then they all will be high and as no line is detected , robot move in a circular motion until line is found. 11
    12. 12. Name of Institution APPLICATION ADVANTAGES DISADVANTAGES Industrial automated equipment carriers. The robot must be capable of following a line. LFR can move on a fixed track or path. Automated cars.  Insensitive to environment factors like noise and lightning. It requires power supply. Tour guides in museums and other similar applications. It should be capable of taking various degrees of turns. Lack of speed control makes the robot unstable at times. Deliver the mail within the office building The color of the line must not be a factor as long as it is darker than the surroundings. Choice of line is made in the hardware abstraction and cannot be changed by software. Deliver medications in a hospital. 12
    13. 13. MICROCONTROLLER CODE Name of Institution #include<regx51.h> void main() { while(1) { if(P1_0==0&&P1_1==0) { P2=0x00; } if(P1_0==1&&P1_1==1) { P2=0xF5; } if(P1_0==0&&P1_1==1) { P2=0xF4; } if(P1_0==1&&P1_1==0) { P2=0xF1; } Keil software is used for microcontroller code and proteus for simulation. } } 13
    14. 14. Name of Institution