SMART interface the Ultrasonic sensor with the

Astha Swaroop
M.E Microelectronics, EEE
Bits-Pilani, Hyderabad Campus
Email: [email protected]
Mobile: 9454933335 Bingumalla Sudheshna
M.E Microelectronics, EEE
Bits-Pilani, Hyderabad Campus
Email: [email protected]
Mobile: 9030902360

I. Abstract:
The sticks which are available in the market are not smart enough to give protection to blinds in their day-to-day life. Scenarios we are trying to address are the protection of blinds against an obstacle, accidentally entering into a water pit or fire. The proposed idea of this project is to a make a stick at an affordable price by removing Microcontroller (Arduino UNO) for interfacing sensor with the buzzer and directly interfacing smart sensor(the concept of the bimetallic strip) with the piezo buzzer. To detect the obstacle Microcontroller (Arduino UNO) is used to interface the Ultrasonic sensor with the piezo buzzer. Sensing of Water can be done using simple physics principle i.e. Electrical conductivity of Water while Sensing of Fire can be done using Expansion of metal on Heating. The power supply is provided to the Microcontroller (Arduino UNO) using the Voltage regulator (Printed Circuit Board), which is fabricated using lithography process.
II. Objectives:
1. Obstacle detection using Ultrasonic sensor
2. Voltage regulator fabrication using lithography process
3. Smart sensor using the Bimetallic strip
III. Motivation / Origin of the project:
1. Approximately 83% of information a human gets through sight.
2. According to the recent WHO analysis, around 285 million people are visually impaired, among which 39 million are blind and 246 million have low vision. Many low-income group people (nearly 90%) are deprived of this critical aid to assist them in their day to day activities.
3. Till now Thermistor is used for sensing fire and Moisture sensor is used for sensing water using Microcontroller, but the proposed idea is to incorporate sensing of both fire and water using a single sensor without using Microcontroller. So that, it is affordable to the people who are under below poverty line.

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IV. Basic state-of-the-art:
# Cited work (paper/ patent product) Highlights Challenge(s) How can you overcome the challenge with your proposed work?
The sensors required for fire detection are one smoke sensor, one flame sensor and, one temperature sensor High cost, complex circuitry and requirement of coding Using a single sensor for detection of fire and easy circuitry at a minimal price
2 Sensing soil moisture using Moisture sensor interfaced with piezo using Microcontroller High cost, complex circuitry, and requirement of coding Using a single sensor for detection of water pit and easy circuitry at a minimal price

V. Timeline:
# Target /Goal Target Date
1 Obstacle detection using Ultrasonic sensor 17th September 2018
2 Voltage regulator fabrication using lithography process 6th October 2018
3 Smart sensor using Bimetallic strip 31st October 2018
4 Report Submission 17th November 2018

VI. Methodology:
1. Obstacle detection using Ultrasonic sensor:
1. Frequencies of the Acoustic waves are above the human audible range, around 40Khz.This high frequency property of Acoustic waves is used in Ultrasonic sensor for measurement purpose.
2. They operate by generating a high-frequency pulse of sound, and then receiving and evaluating the properties of the echo pulse.

Fig 1: Working of the Ultrasonic sensor
• Ultrasonic sensor will activate the buzzer connected with the device when the any obstacle is in the range of 180 degree horizontal and 60 degree vertical, hence will automatically alert the blind person

Fig 2: Ultrasonic senor mounted on a stick
2. Voltage regulator fabrication using lithography process:
Voltage regulator circuit is printed on the PCB using lithography process. The voltage regulator 7805 is mounted on the PCB board. Transformer (8-0-8) converts 220 volts ac voltage to 5 volts. This drives the obstacle sensor and arduino.
3. Smart sensor using the Bimetallic strip:
• Electrical conductivity of water:
Water has the ability to conduct electricity. When the Bimetallic strip is submerged in water, net motion of charged ions present in water takes place. This phenomenon produces an electric current called ionic conduction
• Expansion of Metal on Heating:
A bi-metallic strip can convert a temperature change into mechanical displacement. When a substance is heated, the kinetic energy of its molecules increases and the molecules begin to move more and usually maintain a greater average separation resulting in expansion and closing of the contacts and sounding of the Buzzer.
Thus this smart sensor performs the functions of two individual sensors

VII. Approach and Work done:
• Coding for the obstacle sensor detection:
int const trigger_pin = 10; int const echo_pin = 9; int const buzzer_pin = 13;
void setup()
pinMode(trigger_pin, OUTPUT); // pulse output will be given by trigger pin
pinMode(echo_pin, INPUT); // To define the input of the pulse width pinMode(buzzer_pin, OUTPUT); // To control the buzzer output
void loop()
int duration, distance; // input pulse width, distance to the obstacle in centimeter
digitalWrite(trigger_pin, HIGH);
delay(1); // Output pulse width of 1ms on trigger_pin
digitalWrite(trigger_pin, LOW);
duration = pulseIn(echo_pin, HIGH); // input pulse width in echo pin
// Distance is half the duration divided by 29.1
distance = (duration/2) / 29.1;
// if distance less than 0.5 meter and more than 0
if (distance = 0) {
//Buzz using piezo buzzer
digitalWrite(buzzer_pin, HIGH);
} else {
// Don’t buzz
digitalWrite(buzzer_pin, LOW);
// Wait 60 ms
Any obstacle in the range of 0.5m can be detected by the obstacle sensor
Connected to the arduino programmed and burned with the above code.
• Voltage regulator fabrication using lithography process:
1. Clean the copper coated PCB using ico proponal /acetone and paper towels to make the surface smooth and dust free.Using the laser printer the carbon mask is printed on a transparent (OHP) sheet ,of which the layout is to be designed
2. The dry thin photo resist film (blue color) has a protective layer on both sides with the soft resist material in the middle. Flip film over and remove the bottom side layer easy way, stick a piece of cello tape on each side of a corner of the film, pull the two bits of tape apart, the bottom layer will peel off
3. Laminator is used to improve the adhesion of photo resist to the PCB. Hold film vertical by the tail and feed into laminator, lowering the tail as you go, this eliminates air bubbles. Laminator is operated above 1000C.After lamination; expose the PCB to ultraviolet rays using UV exposer with vacuum for 5minutes.
4. Remove the top transparent layer and then developing it with developer with measurement as 1g sodium carbonate in 100 ml water; swoosh the liquid over it by keeping gap of 10 minutes between exposing and development.
5. Etch the unwanted portions on the PCB using Anhydrous Ferric chloride in a stirrer at 360 rpm. Ionization of Ferric chloride gives copper chloride on the PCB. After etching is completed remove the photo resist with measurement as 5g sodium hydroxide in 100 ml water, and process it for 10 minutes.
3Cu + 2FeCl3 ? 3CuCl2 + 2Fe
6. Drill the PCB using drilling machine to mount the circuit components and at last solder it with soldering iron.
• Smart sensor using the Bimetallic strip:
1. The sensor when comes in contact with water pit, due to the electric current generated, the buzzer will produce an alarming sound. Similarly when the bimetallic strip comes in contact with fire, then due to the difference in thermal expansion coefficients of metals, the bimetallic strip bends towards the contact strip and the the buzzer will produce an alarming sound

Fig3: Sensing a Water pit Fig4: Sensing a Water pit
VIII. Results and Discussion:

Fig 5: PCB board Fig 6: Voltage regulator Fig 7: Bimetallic strip

Fig 7: Blind Stick Fig 8:Obstacle sensor detection
using voltage regulator
IX. Conclusion:
• Obstacle detection using Ultrasonic sensor:
Apart from the obstacle detection for blinds, this can be used for real time applications like an intruder entering to home, counting based applications
• Voltage regulator fabrication using lithography process:
1. A permanent and efficient voltage regulator circuit can be made on a PCB unlike the conventional using of bread board for circuit testing.
2. Contact resistances will be comparatively less
3. High resolution is achieved using UV rays and the circuit is compact in size
• Smart sensor using the Bimetallic strip:
The cost effective, light weight, robust, easy to implement dual functionality
sensor for water and fire detection can be done using bimetallic strip


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