Blog is talking about the smart sensor, actuator, transducers and their different types, components as it is mostly used in IoT technology.
_____________________________________________-
A transducer is a device which converts one form of energy into another form. Alternatively, a transducer is defined as a device which provides usable output response to a specific input measured which may be a physical quantity.
Classification of transducers
Active and Passive
Analog and digital transducer
Transducer and inverse transducer
Primary and secondary transducer
Sensor and its components
Sensors. Is a device which detects or measures a physical property and records, indicates, or otherwise responds to it. Or is an input device which provides an output (signal) with respect to a specific physical quantity (input).
Classification of sensors
In the first classification of the sensors, are divided into two groups, which are Active and Passive sensors
Active Sensors are those which require an external excitation signal or a power signal.
Passive Sensors, on the other hand, do not require any external power signal and directly generates output response.
The second classification is based on the way of detection used in the sensor. Some of these detections are Electric, Biological, and Chemical, Radioactive
The third classification is based on conversion phenomenon i.e. the input and the output. Some of the common conversion phenomena are Photoelectric, Thermoelectric, Electrochemical, Electromagnetic, Thermooptic,
The forth classification of the sensors is Analog and Digital Sensors. Analog Sensors produce an analog output i.e. a continuous output signal with respect to the quantity being measured.
Digital Sensors, The data in digital sensors, which is used for conversion and transmission, is digital in nature. or is an electronic or electrochemical sensor, where data is digitally converted and transmitted.
The mind map of classification of sensors
Different Types of Sensors
The following are different types of sensors which are commonly used:
A temperature sensor is a device, typically, a thermocouple or RTD that provides for temperature measurement through an electrical signal.
A Resistance Temperature Detector (RTD) is a device with a major temperature coefficient (that is, its resistance varies with temperature). It is used as a temperature measurement device usually by passing a low-level current through it and measuring the voltage drop. A thermistor is a type of RTD.
Proximity Sensors is a non-contact type sensor that detects the presence of an object.
An accelerometer is a device that measures changes in gravitational acceleration in a device it may be installed in. To sense motion in multiple directions, an accelerometer must be designed with multi-axis sensors or multiple linear axis sensors.
An infrared sensor is an electronic device that emits in order to sense some aspects of the surroundings. An IR sensor can measure the heat of an object as well as detects the motion.
A pressure sensor is a device that detects a force exerted on a surface (pressure) and converts it to an electronic signal whose strength is relative to the strength of the force. Pressure sensors can also be used to measure the force exerted.
The light sensor is a device which converts light energy of various wavelengths from infrared into the electrical energy.
An Ultrasonic sensor is a device that can measure the distance to an object by using sound waves. It measures distance by sending out a sound wave at a specific frequency and listening for that sound wave to bounce back.
An alcohol sensor detects the attentiveness of alcohol gas in the air and an analog voltage is an output reading. The sensor can activate at temperatures ranging from -10 to 50° C with a power supply is less than 150 Ma to 5V. The sensing range is from 0.04 mg/L to 4 mg/L, which is suitable for breathalyzers.
A touch sensor is equipment that captures and records physical touch or hold on a device or object. It enables a device or object to detect touch, normally by a human user or operator. A touch sensor may also be called a touch detector.
The color sensor detects the color of the surface, usually in the RGB scale. Color is the result of interaction between a light source, an object and an observer. … Color sensors have a variety of applications including detection of environment, choosing the right product and sorting.
Humidity sensor is device that measures and reports the relative humidity in the air. It therefore measures both moisture and air temperature. Relative humidity is the ratio of actual moisture in the air to the highest amount of moisture that can be held at that air temperature.
A tilt sensor is an instrument that is used for measuring the tilt in multiple axes of a reference plane. Tilt sensors measure the tilting position with reference to gravity and are used to enable the easy detection of orientation or inclination.
A level sensor is a device for determining the level or amount of fluids, liquids or other substances that flow in an open or closed system. level sensors are used for measuring levels to a specific limit, but they provide accurate results.
Actuators and actuating technologies.
An actuator is a mechanism for turning energy into motion. An actuator is a device that moves or controls some mechanism. Actuators can be categorized by the energy source they require to generate motion. For example. Actuators can be based on hydraulic, pneumatic, electric, thermal or mechanical. There are two types of actuators:
Rotary actuator: It produces a rotary motion or torque. e.g. stepper motor, servo motor.
Linear Actuators: Linear actuator converts rotary motion into linear motion. There are several types of linear actuators; the most common of them are following;
Mechanical actuators
Mechanical actuators are used as a mechanism to convert mechanical motion into linear motion or with the help of gearing into rotary motion at a different speed. Examples are, Screw, Wheel and axle,
Hydraulic actuators
Hydraulic actuators operate with minimal mechanical parts. They use fluid to force pistons used to facilitate mechanical operation, hydraulic actuators typically take longer to gain speed and power while requiring more time to slow back down.
Pneumatic actuators
Pneumatic actuators, or pneumatic cylinders, use compressed gas to provide pressure instead of fluids or liquids. These actuators also operate with minimal parts. They use air to force pistons. Pneumatic actuators do not require guideline because of air’s compressibility.
Piezoelectric actuators
The Piezoelectric is a property of certain materials in which application of a voltage to the material causes it to enlarge. Very high voltages correspond to only tiny expansions. As a result, piezoelectric actuators can achieve extremely fine positioning decision, but also have a very short range of motion. In addition, piezoelectric materials show hysteresis which makes it difficult to control their expansion in a repeatable manner.
Electromechanical actuators are mechanical actuators where the control knob or handle has been replaced by an electric motor. The rotary motion of the motor is converted into linear displacement. The principle operation in most electromechanical actuators is based on the inclined plane concept. or in other words
An electromechanical actuator is a device that converts electricity to mechanical force in such a way as to perform some type of work, most often physically moving some object or device. They can have a very wide range of shapes, sizes, and designs, but all work on the same basic principle of converting electricity to motive force
MEMS actuators, Micro-Electro-Mechanical Systems, or MEMS, is a technology that can be defined as miniaturized mechanical and electro-mechanical elements that are made using the techniques of micro fabrication.
Magnetic Actuators use magnetic effects to generate forces which impact on the motion of a part in the actuator. This force is proportional to the applied current.
Actuator performance criteria
It has two parts which are static and dynamic loads.Static load is the force capacity of the actuator when there is no motion. On the other hand, the dynamic load of the actuator is the force capacity when there is motion and all these will do it by force. Another are speed, operating conditions which is commonly used by standard IP code rating system and also there is durability which will be determined by each individual producer depending on usage and quality.
Sensors for Localization and Tracking:
Indoor tracking denotes the localization of persons and objects within buildings. This indoor localization is thus a technical challenge because GPS does not work reliably within interior spaces. That’s why they use Wi-Fi or BLE localization depending on the application, (accuracy under 5 meters) using infsoft Locator Nodes or infsoft Locator Tags, which is special hardware developed . Ultra-wideband allows super-precise indoor tracking of people and objects. RFID (Radio frequency identification) enables selective object identification. All solutions presented here also work seamlessly under the open sky in case the plant grounds are not uniformly covered by a roof.
Outdoor tracking uses GPS and A-GPS: GPS stands for Global Positioning System and AGPS stands for Assisted Global Positioning System. GPS devices determine location information by directly communicating with satellites moving around the earth while A-GPS devices are faster as it need not have to go to satellite for information. GPS tracking is the observation of location through use of the Global Positioning System (GPS ) to track the location of an entity or object remotely.
Localization is the process of a product or service to meet the needs of a particular language, culture or desired populations look-and-feel. the process of making something local in character or restricting it to a particular place.
Cooperative localization is a widely used technique for improving performance by utilizing information obtained from adjacent sensors.
Measurement based statistical models (Range Based Localization)
A time difference of arrival (TDOA) is technique has been proposed for providing location services in future UMTS networks. The performance of such a system is limited by errors in the time difference (TD) measurements primarily cause by non-line of sight (NLOS) propagation conditions.
In future systems angle of arrival (AOA) measurements at the serving base station (BS) may be available, primarily as a requirement to increase downlink capacity via beam forming. These measurements may also be useful far location purposes, though they will also be subject to errors caused by NLOS propagation conditions between the mobile (MS) and the serving BS.
The performance improvement of a TDOA location system utilizing the AOA measurement from the serving BS, over a TDOA only system is evaluated. Simulation results are presented which show that location accuracy improvement is possible even in highly NLOS conditions. Furthermore location estimation is now possible when only two BSs are detectable, rather than the three BSs required in the TDOA only system, thus increasing the coverage of the system
In this work a positioning system based on received signal strength (RSS) and WLAN is presented. arget localization and tracking, wireless sensor network (WSN), hybrid measurements, received signal strength (RSS), angle of arrival (AoA)
Target localization and tracking, wireless sensor network (WSN), hybrid measurements, received signal strength (RSS), angle of arrival (AoA)
Recursive position estimation
Recursive hierarchy provides a framework for extending position estimation throughout a sensor network. Given imprecise ranging and inter-node communication, nodes scattered throughout a large volume can estimate their physical locations from a small set of reference nodes using only local information.
Sensor Tasking and Control
Nodes must be carefully tasked to perform the given task while consuming few resources (e.g.,
power, bandwidth)
E.G To detect and track a vehicle, a camera may be tasked to anticipate and follow it
To achieve scalability and autonomy, sensor tasking and control must be done
For a given task, as more sensors participate and more data is collected,
The total utility of the data (e.g., info content) generally increases
But, as nodes are added, resource use (cost) increases and increment in benefit decreases
To address balance between utility and cost, introduce a utility-cost-based approach to SN
management.
Task based sensing it is used by sensing to given activities to be done or events to be done on it.
Sensor resource constraints it uses nodes and board to battery to minimize usage of power a sensor may take on particular role depending on application task requirement and resources availibity such as node power.
Information based sensing by knowing the task of nodes on target state e.g position
Sensor Communication protocols: these are the following sensor communication protocols,
The RS-232 standard had been commonly used in computer serial ports. RS232 is a standard protocol used for serial communication, it is used for connecting computer and its peripheral devices to allow serial data exchange between them. As EIA defines, the RS232 is used for connecting Data Transmission Equipment (DTE) and Data Communication Equipment (DCE).
A driver is needed to use RS232 to microcontroller- MAX232, 16 Pin IC
The RS422 Standard defines a serial communications standard. RS422 is a high speed and long distance data transmission. Each signal is carried by a pair of wires and is thus a differential data transmission system. Over distances up to 40 feet the maximum data rate is 100 Kilobytes per second. Balanced 4 wire system. Two wire is for DTE transmit signal to DCE and other 2 wires is for DCE transmit signal to DTE
The RS485 Standard is similar to the RS422 standard upon which it is based. The main difference is that up to 32 transmitter receiver pairs may be present on the line at one time. A 120 Ohm resistor should be used to terminate either end of the main line. If more than one device may transmit data, the RTS line is used as a transmit enable signal, so reverting contention between talkers.
Serial Peripheral Interface (SPI) is an interface bus commonly used to send data between microcontrollers and small peripherals such as shift registers, sensors, and SD cards. It uses separate clock and data lines, along with a select line to choose the device you wish to talk to. A common serial port, the kind with TX and RX lines, is called “asynchronous” (not synchronous) because there is no control over when data is sent or any guarantee that both sides are running at precisely the same rate
Slave Select (SS)
There’s one last line you should be aware of, called SS for Slave Select. This tells the slave that it should wake up and receives / send data and is also used when multiple slaves are present to select the one you like to talk to.
Advantages of SPI:
It’s faster than asynchronous serial
The receive hardware can be a simple shift register
It supports multiple slaves
Disadvantages of SPI:
It requires more signal lines (wires) than other communications methods
The communications must be well-defined in advance (you can’t send random amounts of data whenever you want)
The master must control all communications (slaves can’t talk directly to each other)
It usually requires separate SS lines to each slave, which can be problem if numerous slaves are needed.
An inter-integrated circuit (Inter-IC or I2C) is a multi-master serial bus that connects low-speed peripherals to a motherboard, mobile phone, embedded system or other electronic devices.
USB — universal serial bus. Short for Universal Serial Bus, an external bus standard that supports data transfer rates of 12 Mbps. A single USB port can be used to connect up to 127 peripheral devices, such as mice, modems, and keyboards. USB also supports Plug-and-Play installation and hot plugging.
The ASi stands for Actuator-Sensor Interface It is a system that links sensors and actuators to a controller over a common data transmission path. This interface connects the modules in the lowest process level in computerization systems with each other.
Bristol Standard Asynchronous/Synchronous Protocol (BSAP) is an industrial computerization protocol developed by Bristol Babcock and managed by Emerson.
The support the following physical layer options.
RS232, RS485, Leased phone line, Satellite, Ethernet, Cellular.
