INTRODUCTION TO SMART SENSORS
World is Growing with emerging technologies, all-conventional systems are being replaced by intelligent automated systems or Simply Artificial intelligent. Peoples keep off from all their works and handing over their duties to AI systems which are fast and efficient than them. This Deviation in peoples work culture started long years back. To be exact, in 1784, the Period of “Industrial revolution” when Peoples started using conventional power sources like Steam engines and water wheels to reduce their effort during work. It was just beginning, the research for ‘minimum effort and maximum output’ were keep going and reached today’s smart world ,But research still going on , now all our requirements are just one switch apart. Within this span of years industry witnessed invention and use of high-end controllers capable of handling variety of operations in wide range of applications. These controllers plays vital role in all kind of automated systems or machineries, How Brain Works for Human Body Similarly Controllers works as Data processing centre for intelligent systems. But we know Brains duty is to receive signals from our sensing organs and process, store and send response to different segments in human body. In other words brain is inactive if there are no inputs to it. The case is similar for controllers, to get output from controllers there must be an input received by controllers. But what could be the input signals? It can be a signal from a Switch which is so common in industries, but we need a human support to operate it. To say a machine is smart or intelligent it must be self-acting, to be so there must be a device capable of detect, measure or Judge condition of field outside it. The evolutions in electronics field contributed invention of such smart devices and named them “Sensors”.
EVOLUTION OF SMART SENSORS
As we talk about industrial revolution, Sensors also came up through different stages of up gradation, as of now this is segmented as five stages of evolution.
First Generation Devices: Beginning stage of sensors, Devices made of Limited Electronics with MEMS sensor Element, Sometimes used with Micro Chips with analog amplification Circuit in it. MEMS means Micro-Electro-Mechanical systems some time known as Microelectronic and MicroElectromechanical systems.MEMS are made up of component size between 1 to 100 micrometers and MEMS based devices size range from 20 micrometers to 1 millimetres.
Second Generation sensors: The second Stage of Sensor MEMS Sensor element along with Analog signal amplification and Analog to Digital convertor on a single microchip.
Third generation sensors: the third generation Sensors included MEMS element, analog amplification, and analog to Digital conversion with Digital intelligence for Linearization and temperature compensation on same micro chip.
Fourth Generation Sensors: to perform Calibration and Temperature compensation Data Processing, The Memory cells was necessary, so the Memory cells added to Third generation sensors and the new one known as fourth generation sensors.
FIFTH GENERATION SENSORS or SMART SENSORS
The semiconductor technology made rapid progress in sensor technologies and today most of the sensors are Smart in nature, hence it is called Smart sensors. How they are smart in nature? Why it is called smart sensors? In simple Smart sensors are sensors that can measure physical conditions of external world and compute, process signals and can communicate with other devices through wired or wireless networks. Most smart sensors are capable of Decision making;self diagnosis and error-correction.to perform all the functions a smart sensor includes circuits of transduction component, Signal conditioning, and a processor or controller that supports required intelligent functions in a single package or microchip.
There are several technologies involved making the Sensors smart, some are 1.MEMS – Micro electro mechanical system that we already talk about, second is 2.VLSI- very large scale integration technology: VLSI is a process of miniaturization of computer chips and implanting large number of transistor gates on a single silicon semiconductor wafer. This technology helps in reducing size of circuits and cost of devicesand increasing speed of and less power consumption. While implementing Sensor nodes in simple or complex networks the size and cost of sensor node is most important. In case of environmental data collection we can use large number of smart sensors deployed at areas of interest on demand or choose random areas. All these sensors are able to sense and process atmospheric data and able to communicate with data centre wirelessly.
COMPONENTS OF SMART SENSOR
The Architectural components of a smart sensor are shown in figure.are as below.
Sensing unit: the physical parameter changes are sensed by Sensing unit and they generate electrical signals corresponding to it.
Signal conditioning unit: this unit manipulates the signal in a way that it meets the requirements for next level operations without losing data.
AnalogTo Digital converter: convert the analog signal to Digital format and sends to the processor.
Processor/Application program: the signals from sensors reaches here and process the data received according to the application programs already loaded here and generate output signals.
Memory: used as the storage media for saving received and processed data.
Communication unit: output signals from processor or application programs are sends to main station is done by communication module. It also receives command requests from main station to perform specific tasks.
Battery: is most important in case of smart sensors especially wireless smart sensors as source of energy.
Nodes in the sensor network communicate together and distribute the data processing tasks and send the processed information’s to the destination.to reduce overhead of the battery in each and every node RFID technology (Radio frequency identification ) with no battery is developed. Sensors are used to monitor different parameters related to atmospheric pressure, temperature, humidity, vehicle movement, noise levels, Lightening conditions, mechanical stress levels, Presence and absence of objects and many other properties.The sensor node mechanism can be thermal, acoustic, radar, seismic or magnetic. Self-identification and self-diagnosis is possible for Sensor node. There are three methods based on how sensor nodes are working.
Towards a Predefined target by a line of sight Ex: Visual sensors
By a wave like Propagation with possible bending Ex: Acoustic sensors
With space and time relationship to target Ex: seismic sensors
As of other networks sensor networks not address centric it is commonly data centric, which means the queries are directed to specific group or cluster of sensors of similar data. The similar data outputs from sensor nodes are sending to common aggregator where all data receives and summarized and analysed.
SOME OF SMART SENSORS
Temperature Sensors: These are devices which measure physical change in temperature from a particular source and convert the data into a format suitable for controller to process. Different types of temperature sensors are available in market depends on technology used in it. Ex: Thermisters, RTD, Infrared sensor..Etc
Proximity sensors: The device that can detect presence or absence of an object or its property without direct contact with that object. Ex: ultrasonic sensors, Photo electric sensors, capacitive proximity sensors.
Pressure Sensors: the sensor that can measure the amount of Pressure applied or atmospheric pressure. Which convert the signal to Electric signals and send to its controllers for further processing. Ex: air pressure sensor, water pressure sensors, atmospheric pressure sensors..etc
Gas and Smoke Sensors: Gas sensors measure the quality of air and detect presence of different gases. A smoke sensor can sense smoke i.e., Airborne particulates and gases and its level
Accelerometer sensors: is a transducer that measure acceleration experienced by an object by inertial forces and converts the physical movement to an electrical signal. Ex: Capacitive accelerometers, piezoelectric accelerometer, and linear Hall Effect accelerometer.
Level Sensors: sensors used to determine the level or amount of fluids. Ex: Float type level sensors, capacitive level sensors, and Liquid level sensors.
Motion detection Sensors: which detect the physical movement motion of an object in a specified area and convert the signal to an electrical signal.
Ex: Passive infrared sensors (PIR), Ultrasonic sensors, Microwave sensors.
Optical sensors: devices or sensors used to detect different light rays and convert the signal in the form readable by its controller or processor. Ex: Pyrometers, Infrared sensors, Proximity sensors, Photo detectors.
Gyroscope Sensors: the sensors used to measure angular rate or angular velocity is known as Gyroscope ex: optical gyroscope, digital gyroscope, vibrating gyroscope, ring laser gyroscope..Etc
Quality sensor: the sensor used to detect quality of particular medium.Ex: PH meter, turbidity sensor, water conductivity sensor
SMART SENSOR APPLICATIONS
Environmental monitoring is very important in today’s environmental condition. It helps to collect environmental data and analyse for weather forecasting purposes and even for judging possible environmental threats like T-tsunami, Flood Etc .environmental monitoring system includes collecting Information or data from smart sensors deployed
Large Geographical area those are communicating each other and with main station through wireless networks.
Traffic monitoring and controlling.
We know the number of vehicles on road is increasing day by day; it increases the number of road accidents and accidental deaths. Careless driving and violation of traffic rules are main reason of increasing accidental death rates in the world. Hence a constant vigil on traffic violations like over speed, drunken drive, wrong side driving is mandatory. Now these days to do these works efficiently, appropriate Smart sensors are placed at specified spots with wireless communication facility. So that any kind of traffic violations can be easily detected and can communicate about the same with traffic station.
Flood and water level monitoring system
It also comes under atmospheric or Environmental monitoring, but because of its importance it is considered at special segment, because natural disasters like Earth quake, cyclone, Flood are important concerns that must be detected and coordinated in fast and efficient manner in order to control its effect at minimal. these can be effectively done by smart sensors of specific purposes deployed at required regions.
Even Agriculture field uses wide range of smart sensors for precision farming or to avoid Losses due to unexpected climate changes. Smart sensors used in agriculture fields for weather prediction, soil and water monitoring… etc.
In industries various kinds of smart sensors used for variety of applications, temperature sensors, pressure sensors, proximity sensors, and photo sensors are just few examples of sensors used industries.
Building and infrastructure:
The innovations in smart sensor technologies can yield really smart buildings that are with enhanced security and facility management, safe and energy saving. various sensors are available for structural monitoring of buildings that can detect any deformation of building structure to notify the authority and take corrective steps.
ADVANTAGES AND DISADVANTAGES OF SMART SENSORS
As sensor nodes and related electronics are on single Microchip , Requirement of interconnecting cable is very less
Because of direct communication with processor reliability and speed of communication is higher
Higher performance level
It is easy to design , use and maintain
Small in size
Sensor calibration has to be done in external processor
Predefined electronic system has to be designed and implemented on sensor chip
Smart sensor consist of both sensors and actuators , so the complexity of circuit is higher and there by cost smart sensors are comparatively higher.
As we discussed our world is growing with technologies That growing day by day , all sectors are make use of intelligent systems to limit human intervention at it s minimal level. An intelligent system or machinery is impossible without sensors. The smart sensors those are capable of sense, self processing of signals and communication facilities plays vital role in all intelligent systems for reliable and fast data processing and communication with center station. In recent technologies Smart wireless sensor networks (WSN) has large potential because of its significance and wide range of applications. The researches on smart sensors are still going on to utilise its potential in all major sectors like defense, biomedical, telecommunication, security , aerospace..Etc. there is no need of doubt that Smart sensor technology is becoming an unbeatable segment of today’s and tomorrows smart world.