Led Display Digital Voltmeter
A role of sensors for industrial applications
Since a significant change involves an exchange of energy, sensors can be classified according the type of energy transfer that they detect. Temperature thermal sensors: thermometers, thermocouples, temperature sensitive resistors (thermistors and detectors temperature resistance), bimetallic thermometers and thermometers
Heat sensors: bolometer, calorimeter
Electric resistance electromagnetic sensors: ohmmeter, multimeter
Electrical current sensors: galvanometer, ammeter
electrical voltage sensors: leaf electroscope, voltmeter
electrical power sensors: watt-hour meters
Magnetism sensors: magnetic compass, fluxgate compass, magnetometer, Hall effect device,
Metal detectors
Mechanical sensors pressure altimeter, barometer, barograph, pressure gauge, air speed indicator, rate of climb indicator, variometer
gas and liquid flow sensors: flow sensor, anemometer, flow meter, gas meter, water meter, mass flow sensors, mechanical sensors: sensor acceleration, position sensor, selsyn, switch, strain gauge
chemical sensors detect the presence of chemicals specific chemicals or classes. Examples include oxygen sensors, also known as lambda sensors, ion selective electrodes, pH electrodes redox glass electrodes.
Optical and electromagnetic radiation of flight time. Build an electromagnetic pulse was issued, and then measure the time of a reflected pulse takes to return. Commonly known as - RADAR (Radio Detection And Ranging) are now joined by analogue LIDAR (detection Light And Ranging. See the following line), are all electromagnetic waves. Acoustic sensors are a special case in which a pressure transducer used to generate a compression wave in a fluid medium (air or water)
light, time of flight. Used in modern surveying equipment, a short pulse light is emitted and returned by a reflector. The flyback pulse is proportional to the distance and is related to atmospheric density in a predictable manner.
Ionizing radiation
Radiation sensors: Geiger counter, dosimeter, Scintillation counter, Neutron detection
Subatomic particle sensors: Particle detector, scintillator, Wire chamber cloud chamber, bubble chamber
Non-ionizing radiation
light sensors or photo detectors, including semiconductor devices such as photocells, photodiodes, phototransistors, CCD sensors and image sensors, the vacuum tube devices like photo-electric tubes, photomultiplier tubes and mechanical instruments, as the Nichols radiometer. infrared sensor, especially used as occupancy sensor for lighting and environmental controls.
-Proximity sensor A type of distance sensor but less sophisticated. Only detects a specific proximity. May be optical - combination of a photocell and LED or laser. Applications in cell phones, paper detector in photocopiers, auto power standby / off mode for laptops and other devices. You can use a magnet and a Hall effect device.
A laser scanning narrow beam of laser light scans the scene by a mirror. A photocell sensor located in the displacement response when the beam is reflected from an object sensor, where the distance is calculated by triangulation.
approach. A large aperture lens may be focused by a servo system. The distance to an element of the scene that has the focus can be determined by the shape of the lens.
binocular. Two images gathered a known base line put in coincidence with a system of mirrors and prisms. The setting is used to determine the distance. It is used in some cameras (called chambers range-finder) and on a larger scale battleship early rangefinder
interferometer. Interference fringes between waves transmitted and reflected light produced by a source coherent as a laser are counted and the distance is calculated. Capable of very high precision.
Scintillometers measure optical atmospheric disturbances.
Acoustic sound sensors: microphones, hydrophones, seismometers.
Acoustic: uses ultrasound time flight echo return. Used in mid 20th century polaroid cameras and applied to robotics. Even older systems like Fathometers (and fish finders) and other "tactics of Active Sonar (Sound Navigation and Ranging) systems in naval applications which mostly use audible sound frequencies.
Other types of motion sensors: radar gun, speedometer, tachometer, odometer, occupancy sensor, turn coordinator
Orientation sensors: gyroscope, artificial horizon, ring laser gyroscope
distance sensor (without contact) Several technologies can be applied to detecting distance: magnetostriction
Not Started systems
Gray code strip or wheel-a number of photo detectors can detect a pattern, creating of a binary number. The gray code is a pattern of mutation that ensures that only one bit of information changes with each step measured, avoiding ambiguities.
Initiated systems
These require starting from a known distance and accumulate incremental changes in measurements.
A square wheel-shaped mask optical disk is driven by a gear train. Two photocells detecting light passing through the mask can be determined a partial revolution of the mask and the direction of rotation.
whisker sensor-A type of touch sensor and proximity sensor.
Classification of measurement errors
A good sensor obeys the following rules:
the sensor must be sensitive to property measure
the sensor should be insensitive to any other property
the sensor should not influence the measured property
In the ideal situation, the signal output of a sensor is exactly proportional to the measured property. The gain is defined as the ratio between output signal and measured property. For example, if a sensor measures temperature and has an output voltage, the gain is a constant with the unit [V / K].
If the sensor is not ideal, several types of deviations can be observed:
The gain in practice can differ from the specified value. This is called a gain error.
Given that the scope of the output signal is always limited, the output signal when the property eventually clip measure exceeds the limits. The full scale range defines outer limits of the property so far as the sensor errors are within the specified range.
If the output signal is zero when the measured property is zero, the sensor has an offset or bias. This is defined as the sensor output at zero input.
If the gain is not constant, this is called nonlinearity. Usually, this is defined by the amount of output differs from ideal behavior in the entire range of the sensor, often noted as a percentage of the entire range.
If the deviation is caused by a rapid change of the measured property over time, there is a dynamic error. Often, this behavior is described with a diagram Shows Bode gain error and phase shift depending on the frequency of a periodic input signal.
If the output signal slowly changes independent of the measured property, this is defined as drift.
Long term drift usually indicates a slow degradation of sensor properties over a long period of time. Noise is a random deviation of the signal varies over time.
Hysteresis is an error caused by the fact that the sensor not immediately follow the change of ownership is measured, so it involves the history of the measured property.
If the sensor has a digital output, the signal is discrete and is essentially an approximation of the measured property. The approximation error is also called digitization error.
If the signal is digitally controlled, limitation of the sampling frequency also causes a dynamic error.
Sensor may to some extent be sensitive to the property other than property being measured. For example, most sensors are influenced by the temperature of their environment.
All these deviations can be classified as systematic errors or random errors. Systematic errors can sometimes be compensated by some kind of calibration strategy. Noise is a random error can be reduced by signal processing such as filtering, usually at the expense of the dynamic behavior of the sensor.
Resolution
The resolution of a sensor is the smallest change that can detect the quantity being measured. Often in a digital display the last significant digit will fluctuate, indicating that changes of this magnitude only just met. The resolution is related to the precision with which the measurement is made. For example, a scanning probe (a fine tip near a surface collects an electron tunneling current) can resolve atoms and molecules.
Biological
All living organisms contain biological sensors with functions similar to those of mechanical devices described. Most of these are specialized cells that are sensitive to:
Light, movement, temperature, magnetic fields, gravity, humidity, vibration, pressure, electrical fields, sound, and other physical aspects of the external environment;
The physical aspects of the internal environment, such as stretching, body movement and position of appendages (proprioception);
an enormous amount environmental molecules, including toxins, nutrients, and pheromones;
Many aspects of the inner half of metabolism such as glucose, oxygen level, or osmolality;
an equally varied range of internal signal molecules like hormones, neurotransmitters and cytokines;
and even the differences between the proteins of the organism itself and of the environment or alien creatures.
Artificial sensors that mimic sensors biological using a biological sensitive component, are called biosensors.
Actuator
Data Acquisition
Data acquisition system
Data logger
Detection theory
Fully Automatic Time
Hydrogen microsensor
Sideline
Limen
List of sensors
Machine olfaction
Features Receiver Operating
Sensor network
About the Author
Assistant professor in lord venkateswara engineering college.I am doing phd in sathyabama university, Tamil Nadu,India.
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