In order to obtain information from the outside world, people must rely on their sensory organs. However, relying solely on our own sensory organs is far from sufficient for studying natural phenomena and laws, as well as for production activities. To adapt to this situation, sensors are needed. Therefore, it can be said that sensors are an extension of the five senses, also known as electrical senses.
Sensors have long permeated an extremely wide range of fields, including industrial production, agriculture, space exploration, ocean exploration, environmental protection, resource surveys, medical diagnosis, bioengineering, and even cultural relic preservation. It is no exaggeration to say that from the vast expanse of space to the boundless ocean, and to various complex engineering systems, almost every modern project relies on a variety of sensors.
In modern industrial production, especially automated production, various sensors are used to monitor and control various parameters in the production process, ensuring that equipment operates in a normal or optimal state and that products achieve the best quality. These parameters include sensitivity, resolution, and accuracy. However, many people are not clear about the differences between these three parameters, leading to various problems during use. Below, we will briefly introduce the differences between sensor sensitivity, resolution, and accuracy.
Sensitivity
Concept: It refers to the ratio of the change in output quantity Δy to the change in input quantity Δx of a sensor under steady-state operating conditions, that is, the ratio of the dimensions of the output and input quantities.
Sensor sensitivity is the slope of the output-input characteristic curve. If the sensor's output and input have a linear relationship, then the sensitivity S is a constant. Otherwise, it will vary with the input. When the dimensions of the sensor's output and input are the same, sensitivity can be understood as the amplification factor. Increasing sensitivity leads to higher measurement accuracy. However, higher sensitivity often results in a narrower measurement range and poorer stability.
resolution
Concept: This refers to the ability of a sensor to detect the smallest change in a measured quantity. In other words, if the input quantity changes slowly from a non-zero value, the sensor's output will not change if the change in input does not exceed a certain value; that is, the sensor cannot distinguish this change in input quantity. Only when the change in input quantity exceeds the resolution will its output change.
Resolution is generally understood as the accuracy of A/D conversion or the smallest perceptible change, while accuracy usually refers to the percentage of error divided by the displayed result, considering factors such as the A/D converter, sensing circuitry, and other factors. For digital instruments, accuracy is typically determined by the number of bits in the A/D converter. Accuracy is the maximum percentage error of the sensor when repeatedly measuring the same standard value; it is an indicator of accuracy after calibration. Resolution is several times better than accuracy. Resolution is negatively correlated with sensor stability.
accuracy
Concept: It refers to the ratio of the value within plus or minus three standard deviations of the true value to the range, which is the maximum difference between the measured value and the true value; resolution—refers to the smallest measured value that causes a change in the indicated value; it should be distinguished from the sensitivity coefficient (sensitivity coefficient—refers to the ratio of output to input).
Generally, domestically produced temperature sensors are classified into two accuracy levels, A and B, according to the national standard: Class A: no greater than ±(0.15℃ + 0.002 * sensor range); Class B: no greater than ±(0.30℃ + 0.005 * sensor range). Therefore, if higher measurement accuracy is required, a sensor with a smaller range should be selected. Resolution is "usually determined by the number of bits in the A/D converter," or by looking at the last digit of its output value.
