The document discusses a distance measurement system utilizing ultrasonic sensors, designed to measure distances in inaccessible areas. It describes the working principle involving an ultrasonic transducer that sends and receives sound waves, calculating the distance based on the time taken for the waves to return. The project requires specific hardware and software, including an 8051 microcontroller and a Keil compiler, and has applications in automotive parking sensors and terrain monitoring robots.

1. Distance Measurement by
Ultrasonic Sensor

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Distance Measurement by Ultrasonic
Sensor
Introduction
 It is designed to measure the distance of any object by using an ultrasonic transducer.
 Ultrasonic means of distance measurement is a convenient method compared to
traditional one using measurement scales.
 This kind of measurement is particularly applicable to inaccessible areas where
traditional means cannot be implemented such as high temperature, pressure zones etc.

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Distance Measurement by Ultrasonic
Sensor
Description
 It uses an ultrasonic module interfaced to a microcontroller of 8051 family.
 An ultrasonic transducer comprising of a transmitter and receiver are used.
 The transmitted waves are reflected back from the object and received by the transducer
again.
 The total time taken from sending the waves to receiving it is calculated by taking into
consideration the velocity of sound.
 Then the distance is calculated by a program running on the microcontroller and displayed
on an LCD screen interfaced to the microcontroller.
 The ultrasonic sensor produces 40 kHz sound waves.

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Distance Measurement by Ultrasonic
Sensor
Working Of Project
 The project uses a pair of ultrasonic transducers comprising of 1 transmitter and 1 receiver.
 The transmitter can deliver 40 KHz ultrasonic sound while the maximum receiver is design
to accept only 40KHz sound waves.
 When ever an obstacle obstructs the signals of ultrasonic transmitter it reflects the signal
towards the ultra sonic receiver.
 The program is so written in MC to calculate the distance getting from ultrasonic module.
 The distance measurement which is seen on LCD displays the distance in cms.

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Distance Measurement by Ultrasonic
Sensor
Block Diagram

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Distance Measurement by Ultrasonic
Sensor
Hardware Requirements
 8051 series Microcontroller
 LCD
 Transformer
 Diodes
 Bridge Rectifier
 Voltage Regulator
 Resistors
 Capacitors
 Ultrasonic Transducers.

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Distance Measurement by Ultrasonic
Sensor
Software Requirements
 Keil compiler
 Language: Embedded C or Assembly

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Distance Measurement by Ultrasonic
Sensor
Ultrasonic Transmitter And Receiver
 Ultrasonic sensors (also known as transceivers) work on a principle similar to radar or
sonar which evaluate attributes of a target by interpreting the echoes from radio or sound
waves respectively.
 Ultrasonic sensors generate high frequency sound waves and evaluate the echo which is
received back by the sensor.
 Ultrasonic generators use piezoelectric materials such as zinc or lead zirconium tartrates
or quartz crystal.
 The material thickness decides the resonant frequency when mounted and excited by
electrodes attached on either side of it.
 The medical scanners used for abdomen or heart ultrasound are designed at 2.5 MHz. In
this circuit, a 40 kHz transducer is used for object detection in the air medium.

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Distance Measurement by Ultrasonic
Sensor
Liquid Crystal Display (Lcd)
 Most common LCDs connected to the microcontrollers are 16x2 and 20x2 displays.
 This means 16 characters per line by 2 lines and 20 characters per line by 2 lines,
respectively.
 The standard is referred to as HD44780U, which refers to the controller chip which
receives data from an external source and communicates directly with the LCD.

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Distance Measurement by Ultrasonic
Sensor
How to Operate this Ultrasonic Distance Measurement by
Circuit
 Initially burn the program to the microcontroller.
 Now give the connections as per the circuit diagram.
 While giving the connections make sure that Vcc of ultrasonic module is connected to
5V DC.
 Switch on the board supply.
 Place the obstacle in front the ultrasonic module, now you can observe the distance on
LCD.
 Switch off the board supply.

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Distance Measurement by Ultrasonic
Sensor
Ultrasonic Distance Measurement Applications:
 Used to measure the obstacle distance.
 This system used in automotive parking sensors and obstacle warning systems.
 Used in terrain monitoring robots.

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