How to select the appropriate sensor

How to select the appropriate sensor

When we provide sensing solutions, it is very important to choose the right products. There are so many kinds of sensors. Once the selection is not good, it will bring a lot of issues to the application.

① Choose the type of sensor depends on measurement object and measurement environment

To carry out a specific measurement work, it is necessary to consider the principle of the sensor, which needs to analyze various factors before selection.

Because, even if it is to measure the same measurement object, there are also a variety of principles of the sensor available for selection, which kind of principle of the sensor is more appropriate, depend on the characteristics of the measurement and the use of the sensor to consider the following specific issues:

The size of the range;

The requirements of the measured position on the volume of the sensor;

Contact or non-contact measurement method;

Signal eliciting method, wire transmission or wireless transmission. After considering the above selections, it can be determined which type of sensor to choose, and then the specific performance and specification of the sensor can be considered.

②  Selection of sensitivity

In general, within the linear range of the sensor, you want the sensor to be as sensitive as possible.

Because only when the sensitivity is high, the value of the output signal corresponding to the measured change is relatively large, this is easy for signal processing.

However, it should be noted that the sensitivity of the sensor is high, and the external noise unrelated to the measurement is easy to mix in, and will be amplified by the amplification system, affecting the measurement accuracy.

3. Frequency response characteristics

The frequency response characteristic of the sensor determines the frequency range to be measured, and the measurement condition must be kept within the allowable frequency range without loss of truth. In fact, the response of the sensor always has a constant delay, and the shorter the delay time is, the better.

The high frequency response of the sensor, its measurable signal is wide. Due to the influence of the structural characteristics, the inertia of the mechanical system is larger, a low frequency response of the sensor, its measurable signal is lower frequency.

In the dynamic measurement, the response characteristics (steady state, transient, random, etc.) of the signal should be considered to avoid excessive errors.

4. Linear range

The linear range of a sensor is the range in which the output is ratiometric to the input.

Theoretically, the sensitivity remains constant within this range.

The wider the linear range of the sensor is, the larger the measuring range is, and the measurement accuracy can be guaranteed.

When selecting sensors, when the type of sensor is determined, the first thing to look at is whether the range meets the requirements.

But in fact, no sensor can guarantee absolute linearity, and its linearity is relative.

When the required measurement accuracy is relatively low, the sensor with small nonlinear error can be regarded as linear approximately within a certain range, which will bring great convenience to the measurement.

5. Stability

The ability of a sensor to remain unchanged over time is called stability.

Besides the structure of the sensor, the main factor that affects the long-term stability of the sensor is the environment of the sensor.

Therefore, to make the sensor have good stability, the sensor must have a strong environmental adaptability.

Before the selection of sensors, the environment should be investigated, and appropriate sensors should be selected according to the specific environment, or appropriate measures should be taken to reduce the impact of the environment.

There are quantitative indicators for the stability of the sensor. After the use period, the sensor should be calibrated again before use to determine whether the performance of the sensor changes.

In some cases where the sensor is required to be used for a long time and cannot be easily replaced or calibrated, the selected sensor should have more stringent stability requirements and be able to stand the test for a long time.

6. Accuracy,

Accuracy is an important performance index of sensor. It is an important link related to the measurement precision of the whole measurement system.

The higher the accuracy of the sensor, the more expensive it is. Therefore, the accuracy of the sensor only needs to meet the accuracy requirements of the whole measurement system, so it is not necessary to choose too high.

In this way, the cheaper and simpler sensor can be selected among many sensors that meet the same measurement purpose.

If the purpose of measurement is qualitative analysis, select the sensor with high repeat accuracy, not the absolute value of high precision;

If it is for quantitative analysis, it is necessary to obtain the accurate measurement value, then it is necessary to select the sensor whose accuracy level can meet the requirements.

For some special application, if there is no appropriate sensor, the need a customized sensor.

Customized sensor should meet the special application requirements.

In general, if the above points are taken into consideration, the appropriate sensor can be selected.