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  • 8/13/2019 obstacle detection robot




    Mini project

    Submitted in partial fulfilment of the requirements for the award of the degree


    Bachelor of technology


    Electrical and Electronics Engineering



    Anusree Nagendran B090121EE

    K. Neetusha B090027EE

    Radhika Krishnan B090229EE

    Tara Elizabeth Thomas B090189EE

    Under the guidance of


    Department of Electrical and Electronics Engineering


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    This is to certify that the report entitled OBSTACLE DETECTI ON ROBOT is a bona

    fide record of the mini-project done byANUSREE NAGENDRAN (B090121EE), K.


    ELI ZABETH THOMAS (B090189EE) in partial fulfilment of the requirements for the

    award of Degree of Bachelor of Technology in Electrical & Electronics Engineering from

    National Institute of Technology Calicut for the year 2012.

    Dr.Jeevamma Jacob Dr. Sreeram Kumar(Project Guide) Professor & Head


    Place: NIT CALICUT

    Date: 3.5.2012

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    At the very outset, we give all thanks to God almighty, who blessed us with the strength to

    do this project. We express our sincere gratitude to our guide, Dr.Jeevamma Jacob,

    Professor, Department of Electrical and Electronics Engineering, for her guidance and

    support throughout this endeavour. We thank Dr. Sreeram Kumar, Head of the

    Department, for providing all the facilities required for the project in the Department. We

    would like to extend our sincere thanks to Ananthakrishnan Sir, miniproject co-ordinator

    for giving us an opportunity to work in this project area. We also express our gratitude to

    Mr. Anand K.R(Lab Staff) and Mr. Somanath for their dedication and sincere interest in

    our work without which this project would not have been successful.

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    This project aims at building a basic model of an obstacle detection robot using 8051

    microcontroller and infra red proximity sensors. The model uses a three wheeled

    differential drive configuration, with castor wheel and is powered by a DC voltage source

    of 12 Volts. The robot is designed so that as soon as it detects an obstacle directly in front

    of it, it goes in the reverse direction and then turns and proceeds along a path with no

    immediate obstacles. IR leds whose frequencies are modulated to 38 KHz with the help of

    an astable multivibrator circuit using 555 timer IC emit the IR rays, which get reflected and

    comes back if an obstacle is present in its path. TSOP 1738 senses these rays changes its

    output voltage level from high to low. This is given as an external hardware interrupt to the

    microcontroller, which decides the action to be taken as per the source code.

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    1. Introduction2. Objective3. System Model

    3.1 AT89C51

    3.1.1 General Description

    3.1.2 Features

    3.1.3 Pin Description of AT89C51

    3.2 Infra Red Sensor Module

    3.2.1 TSOP 1738

    3.2.2 Astable Multivibrator Circuit for frequency modulation.

    3.3 The Movement Control System

    3.3.1 L293D

    3.3.2 Two wheeled Differential Drive with Castor Wheel4. Source Code

    5. Circuit Diagram

    6. Results

    7. Future Enhancements

    8. Conclusion

    9. References

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    With the increasing importance and popularity of autonomous machines in the global scenario,

    robotics is a field that captures much attention and interest. This vast topic is built upon the

    basics of electrical, electronics and mechanical engineering. The ability of to move smoothly,

    avoiding the obstacle in its path is an essential need of any autonomous robot, irrespective of

    its specific purpose. One of the most economical ways to implement obstacle avoidance is by

    using IR radiations and corresponding sensors. In this mini project, we tried to develop a

    miniature robot that has this quality, so that this basic model can be the foundation for variety

    of specific purpose robots in future by incorporating additional sensors and by adding to the

    code of the program.

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    2. OBJECTIVEThis project aims to design and build a basic robot, which moves in a straight line till it detects

    an obstacle. On detecting an obstacle in its path, using its IR proximity sensor, the robot

    automatically turns and finds a path without an immediate obstacle and continues its motion till

    the next obstacle is encountered.

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    3.1 AT89C51

    3.1.1 General Description

    The AT89C51 is a low-power, high-performance CMOS 8-bit microcomputer with 4K bytes of

    Flash programmable and erasable read only memory (PEROM). The device is manufactured

    using Atmels high-density nonvolatile memory technology and is compatible with the

    industry-standard MCS-51 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 AT89C51 is a

    powerful microcomputer which provides a highly-flexible and cost-effective solution to many

    embedded control applications.

    Figure 1: 89C51 Microcontroller

    3.1.2 Features:

    4K bytes of Flash 128 bytes of RAM 32 I/O lines Two 16-bit timer/counters A five vector two-level interrupt architecture 80C51 Central Processing Unit Speed up to 33 MHz Full static operation 4 level priority interrupt 6 interrupt sources Four 8-bit I/O ports

    Automatic address recognition Programmable clock out

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    Second DPTR register Asynchronous port reset Low EMI (inhibit ALE) 3 16-bit timers A full duplex serial port, on-chip oscillator and clock circuitry. Wake up from power down by an external interrupt In addition, the AT89C51 is designed with static logic for operation down to zero

    frequency and supports two software selectable power saving modes.

    The Idle Mode stops the CPU while allowing the RAM, timer/counters, serial port andinterrupt system to continue functioning.

    The Power-down Mode saves the RAM contents but freezes Pin Description.

    Figure 2: AT89C51 Pinout

    3.1.3 Pin Description Of AT89C51

    Port 0: Port 0 is an 8-bit open-drain bi-directional I/O port. As an output port, each pin can

    sink eight TTL inputs. When 1s are written to port 0 pins, the pins can be used as

    highimpedance inputs. Port 0 may also be configured to be the multiplexed low order

    address/data bus during accesses to external program and data memory . In this mode P0

    has internal pullups. Port 0 also receives the code bytes during Flash programming, and

    outputs the code bytes during program verification. External pullups are required during

    program verification.

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    Port 1:It is an 8-bit bi-directional I/O port with internal pullups. The Port 1 output buffers can

    sink/source four TTL inputs. When 1s are written to Port 1 pins they are pulled high by the

    internal pullups and can be used as inputs. As inputs, Port 1 pins that are externally being

    pulled low will source current (IIL) because of the internal pullups. Port 1 also receives the

    low-order address bytes during Flash programming and verification.

    Port 2:It is an 8-bit bi-directional I/O port with internal pullups.The Port 2 output buffers can

    sink/source four TTL inputs.When 1s are written to Port 2 pins they are pulled high bythe

    internal pullups and can be used as inputs. As inputs,Port 2 pins that are externally being pulled

    low will sourcecurrent (IIL) because of the internal pullups. Port 2 emits the high-order address

    byte during fetches from external program memory and during accesses to external data

    memory that use 16-bit addresses (MOVX @DPTR). In this application, it uses strong internal

    pullupswhen emitting 1s. During accesses to external data memory that use 8-bit addresses

    (MOVX @ RI), Port 2 emits thecontents of the P2 Special Function Register. Port 2 also

    receives the high-order address bits and some control signals during Flash programming andverification.

    Port 3: It is an 8-bit bi-directional I/O port with internal pullups. The Port 3 output buffers can

    sink/source four TTL inputs. When 1s are written to Port 3 pins they are pulled high by the

    internal pullups and can be used as inputs. As inputs, Port 3 pins that are externally being

    pulled low will source current (IIL) because of the pullups.Port 3 also serves the functions of

    various special featuresof the AT89C51 as listed below: Port 3 also receives some control

    signals for Flash programming and verification.

    RST: A high on this pin for two machine cycles while the oscillator is running resets thedevice.

    ALE/PROG: Address Latch Enable output pulse for latching the low byte of the address

    during accesses to external memory. This pin is also th