In our day-to-day life we frequently use different types of sensors in several applications such as IR sensor used for operating television remote, Passive Infrared sensor used for automatic door opening system of shopping malls and LDR sensor used for outdoor lighting or street lighting system, and so on. In this article we will discuss about a few types of sensors and their applications in brief. But, primarily we must know what is a sensor.
What is a Sensor?
A device that detects the changes in electrical or physical or other quantities and thereby produces an output as an acknowledgement of change in the quantity is called as a Sensor. Generally, this sensor output will be in the form of electrical or optical signal.
Different Types of Sensors
The most frequently used different types of sensors are classified based on the quantities such as Electric current or Potential or Magnetic or Radio sensors, Humidity sensor, Fluid velocity or Flow sensors, Pressure sensors, Thermal or Heat or Temperature sensors, Proximity sensors, Optical sensors, Position sensors, Chemical sensor, Environment sensor, Magnetic switch sensor , etc.
Different Types Of Sensors With Their Applications
Typical applications of different types of sensors such as application of Speed sensor for synchronizing the speed of multiple motors, Temperature sensor application for industrial temperature control, application of the PIR sensor for automatic-door-opening system, Ultrasonic sensor application for distance measurement, etc., are discussed below with their block diagrams.
Sensors used for detecting speed of an object or vehicle is called as Speed sensor. There are different types of sensors to detect the speed such as Wheel speed sensors, speedometers, LIDAR, ground speed radar, pitometer logs, doppler radar, air speed indicators, pitot tubes and so on.
Application of Speed Sensor
PIC microcontroller based project for speed synchronization of multiple motors in industries using wireless technology is a typical application of the speed sensor. One of the multiple motors in the industry is considered as a main motor which act as transmitter and remaining motors acting as receivers, will follow the speed of the main motor. The main motor and receiver motors used in this project are BLDC motors that are controlled using PWM control with the radio frequency wireless communication mode.
Reference RPM is given to each motor shaft which has an IR sensor mounted and a closed loop is obtained by feeding this output to controller in the circuit. Full speed will be displayed on display unit and required speed of all motors can be obtained by entering the desired percentage using the keypad. This entered percentage is matched with running RPM by maintaining appropriate DC power to motor with automatic adjustment of pulse width output of microcontroller.
Thus, by varying speed of transmitting motor, we can change the speed of all motors using this technology.
A device which gives temperature measurement as an electrical signal is called as Temperature sensor. This electrical signal will be in the form of electrical voltage and is proportional to the temperature measurement.
There are different types of sensors used for measuring temperature, such as Contact type temperature sensors, Non-contact type temperature sensors. These are again subdivided as Mechanical temperature sensors like Thermometer and Bimetal. Electrical temperature sensors like Thermistor, Thermocouple, Resistance thermometer and Silicon band gap temperature sensor.
Application of Temperature Sensor
Design of Industrial Temperature Controller for controlling temperature of devices used in industrial applications is one of the frequently used practical applications of the temperature sensor. In this circuit IC DS1621, a digital thermometer is used as a temperature sensor, thermostat, which provides 9-bit temperature readings. The circuit mainly consists of 8051 microcontroller, EEPROM, temperature sensor, LCD display and other components.
LCD is used to display temperature in the range of -55degress to +125degrees. EEPROM is used to store predefined temperature settings by user through the 8051 series microcontroller. The relay whose contact is used for load, is driven by microcontroller using a transistor driver.
An electronic sensor used for measuring the infrared light radiation emitted from objects in its field of view is called as a PIR sensor or Pyroelectric sensor. Every object that has a temperature above absolute zero emit heat energy in the form of radiation radiating at infrared wavelengths which is invisible to the human eye, but can be detected by special purpose electronic devices such as PIR motion detectors.
PIR sensor itself is split into two halves, which are sensitive to IR and whenever object comes in the field of view of the sensor, then positive differential change will be produced between two halves with the interception of the first half of the PIR sensor. Similarly, if the object leaves the field of view, then negative differential change will be produced. PIR or Passive Infrared sensor is named as passive because it doesn’t emit any energy or radiation for detecting the radiation. There are different types of sensors used for detecting the motion and these PIR sensors are classified based on angle (wide area) over which they can detect motion of the objects like 110degrees, 180degrees and 360degress angles.
Application of PIR Sensor
Automatic Door Opening System is a typical application of PIR sensors which is intended for automatic door closing and opening operations based on body movement near the door. PIR-sensor-based-automatic-door- opening system circuit mainly consists of a PIR sensor, an 8051 micrcontroller, a driver IC, a door motor.
If a body movement is present near the door, then infrared radiation emitted from the body will cause the sensor to produce sensing signal which is fed to microcontroller. The door motor is then controlled and operated by the microcontroller through driver IC. Thus, if anybody comes near to door, then a command will be sent by microcontroller for opening door and a time delay is set for closing door automatically. This project is intended for operating doors of shopping malls, theatres and hotels.
The principle of ultrasonic sensor is similar to sonar or radar in which interpretation of echoes from radio or sound waves to evaluate the attributes of a target by generating the high-frequency-sound waves (around 40kHz). The transducer used for converting energy into ultrasound or sound waves with ranges above human hearing range is called an ultrasonic transducer.
Application of Ultrasonic Sensor
The distance measurement at inaccessible areas is a typical application of ultrasonic sensors. The circuit consists of an ultrasonic module, LCD display and microcontroller. The ultrasonic module is interfaced with the microcontroller and this ultrasonic transducer consists of a transmitter and receiver.
The waves transmitted by transducer are received back again after the waves are reflected back from the object. The velocity of sound is considered for calculating time taken for sending and receiving waves. The distance is calculated by executing a program on microcontroller, and then it is displayed on the LCD display.
There are many sensors such as humidity sensor, gas sensor, pressure sensor, water sensor, leaf sensor, rain sensor, tilt sensor, rate sensor and so on, which are being used in many applications. If you are interested to know in detail about sensors, then you can approach us for any technical help regarding different types of sensors and their applications and also to develop sensor based projects by posting your queries in comments section below.