Sensors are almost indispensable in modern industrial production, especially in automated production processes. It is the link between the mechanical system and the control system of the equipment. The mechanical system feeds back the motion parameters and running state to the control system through the sensor, and the control system sends out instructions to drive the mechanical system through the signal and data feedback from the sensor. Its importance is self-evident.
Sensors are an extension of human features, also known as electrical features. Equipment control system needs to determine: the location of the organization, the presence or absence of products, and the accuracy of products and other important parameters to monitor and control the use of equipment and product production process. Specifically, industrial producers need to use various sensors to monitor and control various parameters in the production process, so that the equipment is in a normal state, and if there is a fault, it can be found in time.
This paper mainly sorts out five common types of industrial sensors in the field of industrial automation.
1, photoelectric sensor
Photoelectric sensor is a device that converts optical signals into electrical signals. Its working principle is based on the photoelectric effect. Photoelectric effect refers to the phenomenon that when light shines on some substances, the electrons of substances absorb the energy of photons and the corresponding electrical effect occurs. According to the different phenomena of photoelectric effect, photoelectric effect can be divided into three categories: external photoelectric effect, internal photoelectric effect and photovoltaics effect. Photoelectric devices include photocell, photomultiplier tube, photoresistor, photodiode, phototransistor, photocell and so on.
Photoelectric sensors have the characteristics of high resolution, short response time, long detection distance, and less restrictions on the detection of objects. In particular, it enables color discrimination. The reflectivity and absorption of light formed by detecting objects vary according to the wavelength of the light being cast and the color combination of the detected object. Using this property, the color of the detected object can be detected.
2, proximity sensor
Proximity sensor can be non-contact sensing detection, so there will be no wear and damage to the test object, no spark, no noise. Because of the contactless output mode, so the service life is long, almost no impact on the life of the contact. Proximity sensor is different from other detection methods in that it is suitable for and used in water and oil environment, and it is almost not affected by the stains and water and oil of the detection object.
Among them, the proximity sensor itself can only detect metal objects at a close distance and without contact. The most characteristic of the ranging change type elastic rod device is that it can overload the sensing range of the contact. Spring-loaded pistons, probes and buttons are generally used to contact the product and then check whether the product is in place, positioning is accurate and verify the product under test.
3. Optical fiber sensor
The use of optical fiber to develop optical fiber sensor began in 1977, the technology has aroused great interest, at present, optical fiber sensor has been rapidly developed. Because the optical fiber itself is a dielectric, and the sensitive element can also be made of dielectric materials, so the optical fiber sensor has good electrical insulation, optical fiber surface can withstand 80kV / 20cm voltage, especially suitable for high voltage power supply system and large capacity motor test, can be used in high voltage, electrical noise, high temperature, corrosion, or other harsh environment, And it has inherent compatibility with optical fiber telemetry technology.
Optical fiber can be used to form a wide variety of sensors, so some people say that optical fiber sensor is universal sensor. It can measure many physical quantities, and its application range is all over the military, commercial, civil, medical, industrial control and other fields. It should be made clear that traditional sensors are based on mechano-electrical measurements, while fiber optic sensors are based on optical measurements.
4, displacement sensor
Displacement sensor is a device that converts the movement of an object into a measurable electrical quantity. It is usually used to convert physical quantities such as deformation, vibration, displacement, position and size that are not convenient for quantitative detection and processing into electrical quantities that are easy for quantitative detection and information transmission and processing.
There are many kinds of displacement sensors. In recent years, the application field is expanding, and more and more innovative technologies have been applied to the sensors. For example, based on fiber optic technology, time gate technology, OEM LVDT technology, ultrasonic technology, magnetostrictive technology, etc., the performance of various sensors has been greatly improved and the cost has been significantly reduced due to the advancement of technology.
5. Hall effect sensor
Rotating Hall-effect sensors generally do not use any moving parts. This semiconductor-based sensor combines Hall-effect sensing elements with circuits to provide an analog output signal corresponding to changes in the rotating magnetic field. Two output options are available, namely analog or pulse width modulation (PWM).
Among them, the linear Hhall effect sensor measures the linear motion of the magnetic field, rather than the rotation. The sensor can be programmed for a set output voltage that is proportional to a given distance traveled. Up to now, the related technology of Hall sensor is still in the process of continuous progress, programmable Hall sensor, intelligent Hall component and micro Hall sensor will have a good market prospect.
Summary:
With the arrival of new technological revolution, the world began to enter the information age. In the process of using information, the first thing to be solved is to obtain accurate and reliable information, and sensor is the main way and means to obtain information in the field of nature and production. In modern industrial production, especially in the automation production process, various sensors should be used to monitor and control the various parameters in the production process, so that the equipment works in the normal state or the best state, and the product reaches the best quality. Therefore, it can be said that without many excellent sensors, modern production will lose its foundation.
The characteristics of sensor include miniaturization, digitalization, intelligence, multi-function, systematization, network, etc. It not only promotes the transformation and upgrading of traditional industries, but also may establish new industries, thus becoming a new economic growth point in the 21st century.
In the next few years, with the acceleration of intelligent manufacturing, the market demand for intelligent sensing, monitoring, production and monitoring systems, technologies and equipment is expected to rise further. Among them, different types of sensors will be carried in common automotive electronics, communication electronics, consumer electronics and special electronic devices. In order to better meet customer needs, enterprises will also be committed to the development of more high quality sensor new products.