Sensor selection rules

There are many kinds of sensors on the market now, and the principle and structure are very different. How to select the sensor reasonably according to the specific measurement purpose, measurement object and measurement environment is the first problem to be solved when measuring a certain quantity. When the sensor is determined, the measuring method and measuring equipment that match it can be determined. When we provide solutions, choosing the right product is a very important link. As far as sensors are concerned, there are many types. Once the selection is not good, it will bring a lot of trouble to the later work. Here are a few summary A simple way to choose a sensor.

  1) Determine the sensor type according to the measurement object and measurement environment

To carry out a specific measurement work, we must first consider what kind of sensor principle is used, which can be determined after analyzing many factors. Because even if it is measuring the same physical quantity, there are sensors with multiple principles to choose from. Which type of sensor is more suitable, you need to consider the following specific issues according to the characteristics of the measured and the use conditions of the sensor: the size of the range; The measured position requires the volume of the sensor; whether the measurement method is contact or non-contact; the signal extraction method, wired or non-contact measurement; the source of the sensor, whether domestic or imported, and whether the price can be affordable, or self-developed.

  2) Selection of sensitivity

Generally, within the linear range of the sensor, it is hoped that the higher the sensitivity of the sensor, the better. Because only when the sensitivity is high, the value of the output signal corresponding to the measured change is relatively large, which is beneficial to signal processing. But it should be noted that the sensitivity of the sensor is high, and external noise that has nothing to do with the measurement is also easy to mix in, and it will also be amplified by the amplification system and affect the measurement accuracy. Therefore, it is required that the sensor itself should have a high signal-to-noise ratio, and try to reduce the factory disturbance signal introduced from the outside world.

  3) Frequency response characteristics

The frequency response characteristics of the sensor determine the frequency range to be measured, and the measurement conditions must be maintained without distortion within the allowable frequency range. In fact, the response of the sensor always has a fixed delay, and it is hoped that the delay time is as short as possible. The frequency response of the sensor is high, the signal frequency range that can be measured is wide, and due to the influence of the structural characteristics, the inertia of the mechanical system is larger, and the frequency of the measurable signal is lower due to the low frequency sensor.

  4) Linear range

The linear range of the sensor refers to the range where the output is proportional to the input. In theory, the sensitivity remains constant within this range. The wider the linear range of the sensor, the larger the measuring range, and a certain measurement accuracy can be guaranteed. When selecting a sensor, when the type of sensor is determined, it is first necessary to see whether its range meets the requirements. But in fact, no sensor can guarantee the linearity of ^, and its linearity is also relative. When the required measurement accuracy is relatively low, within a certain range, the sensor with less nonlinear error can be approximately regarded as linear, which will bring great convenience to the measurement.

  5) Stability

The ability of the sensor to keep its performance unchanged after a period of use is called stability. In addition to the structure of the sensor itself, the factors affecting the long-term stability of the sensor are mainly the use environment of the sensor. Therefore, to make the sensor have good stability, the sensor must have strong environmental adaptability. Before selecting a sensor, investigate its use environment, and select the appropriate sensor according to the specific use environment, or take appropriate measures to reduce the environmental impact.

  6) Precision

Accuracy is an important performance index of the sensor, and it is an important link related to the measurement accuracy of the entire measurement system. The higher the accuracy of the sensor, the more expensive its price. Therefore, the accuracy of the sensor only needs to meet the accuracy requirements of the entire measurement system, and it is not necessary to select too high. In this way, a cheaper and simpler sensor can be selected among many sensors that meet the same measurement purpose.