There are many types of sensors for engineering automation monitoring, which can be divided into displacement sensors, stress-strain sensors, pressure sensors, etc. according to the measured physical quantities. The following are some common types:
Displacement sensor
Fiber Bragg Grating Displacement Sensor: Utilizing the relationship between the Bragg reflection wavelength of fiber Bragg gratings and strain, temperature, displacement changes are converted into wavelength changes for measurement. It has the advantages of anti electromagnetic interference, high accuracy, and distributed measurement, and is suitable for long-term monitoring and displacement measurement in complex electromagnetic environments, such as deformation monitoring of structures such as dams and bridges.
Laser displacement sensor: By emitting a laser beam, the time or phase difference between the emission and the reflection of the laser beam from the object is measured, and the distance change between the sensor and the object is calculated to obtain the displacement. It has the characteristics of non-contact measurement, high accuracy, and fast response speed, and is commonly used for monitoring the displacement of foundation pits and controlling the position of cranes in construction.
Inductive displacement sensor: Based on the principle of electromagnetic induction, when the armature moves with the measured object, it changes the inductance of the coil, and the displacement size is determined by measuring the change in inductance. It has the advantages of simple structure, reliable operation, and high resolution, and can be used for displacement measurement in mechanical processing, small displacement monitoring of building structures, etc.
Stress strain sensor
Resistance strain gauge: It is a sensor that operates based on the resistance strain effect of metal wires or semiconductor materials. When the measured object deforms, the strain gauges attached to the surface of the object also deform, causing a change in its resistance value. The strain of the object is calculated by measuring the change in resistance value. It has the advantages of small size, light weight, high measurement accuracy, and low price, and is widely used in stress-strain measurement of various engineering structures, such as bridges, buildings, mechanical components, etc.
Vibration string strain sensor: Using the relationship between the natural frequency of the steel string and the tension it is subjected to, the strain is converted into the frequency change of the steel string for measurement. It has the characteristics of high accuracy, good stability, and strong anti-interference ability, and is commonly used for long-term stress-strain monitoring of large engineering structures such as dams and tunnels.
Fiber optic strain sensor: Based on the elastic optical effect of optical fibers, when the fiber is subjected to strain, its refractive index and geometric dimensions will change, resulting in changes in the phase, wavelength, and other characteristics of light propagation in the fiber. Strain information can be obtained by measuring the changes in these optical signals. It has the advantages of corrosion resistance, electromagnetic interference resistance, and distributed measurement, and is suitable for strain monitoring of engineering structures in harsh environments, such as underwater tunnels, nuclear power plants, etc.
Pressure sensor
Piezoelectric pressure sensor: Based on the piezoelectric effect of piezoelectric materials, when pressure is applied to the piezoelectric material, a charge or voltage signal proportional to the pressure will be generated. It has the advantages of high frequency response, high sensitivity, and small size, and is commonly used for dynamic pressure measurement, such as engine combustion pressure monitoring, hydraulic system pressure monitoring, etc.
Piezoresistive pressure sensor: Utilizing the piezoresistive effect of semiconductor materials, when pressure is applied to the sensitive element of the sensor, the resistance value of the sensitive element will change. The pressure is measured by measuring the change in resistance value. It has the characteristics of high precision, good linearity, and good temperature stability, and is widely used in pressure measurement in industrial automation, automotive electronics, medical equipment, and other fields.
Capacitive pressure sensor: Based on the principle of capacitance, when pressure is applied to the elastic diaphragm of the sensor, the diaphragm will deform, causing a change in the distance or area between the capacitor plates, thereby changing the capacitance value. The pressure is measured by measuring the change in capacitance value. It has the advantages of high sensitivity, fast response speed, and low power consumption, and is commonly used for small pressure measurement and high-precision pressure monitoring.
Other sensors
Acceleration sensor: used to measure the acceleration of objects, common ones include piezoelectric acceleration sensors, piezoresistive acceleration sensors, etc. In engineering automation monitoring, it can be used to monitor the vibration acceleration of structures such as bridges and buildings under earthquake and wind loads, and evaluate the dynamic response and safety of the structures.
Temperature sensor: used to measure the temperature of the environment or objects, such as thermocouples, thermistors, thermistors, etc. In engineering monitoring, temperature sensors can be used to monitor the internal temperature changes of concrete structures and prevent concrete from cracking due to temperature stress; It can also be used to monitor the temperature of electrical equipment to ensure safe operation of the equipment.
Humidity sensor: Used to measure environmental humidity, common types include capacitive humidity sensors, resistive humidity sensors, etc. In some engineering environments with high humidity requirements, such as underground engineering and cultural relic protection projects, humidity sensors can monitor the environmental humidity in real time in order to take corresponding moisture-proof and dehumidification measures.
