Definition of three concepts of tension sensor activation, precision and resolution

Generally, the degree of sensitivity, precision, and resolution of the pressure sensor and the temperature sensor will be described within a few hours. However, many people are not very clear about the difference between these three parameters, which makes it easy to present large and small problems when they are used. Next, I will briefly introduce the differences between sensor mobility, accuracy, and resolution.

Activity degree

Concept: Refers to the ratio of the output change Δy of the sensor under steady-state operation to the input change Δx, that is, the ratio of the output to the input size. For example, when a displacement sensor changes displacement by 1 mm, the output voltage changes to 200 mV, and its activity should be expressed as 200 mV/mm. The activity of the sensor is the slope of the output-input characteristic curve. If there is a linear relationship between the output of the sensor and the input, the mobility S is constant. Otherwise, it will change as the amount of input changes. When the output of the sensor and the dimension of the input amount are the same, the degree of activity can be understood as a magnification. Progressive activity can achieve higher measurement accuracy. However, the higher the mobility, the narrower the measurement range and the worse the stability.

Precision
Concept: refers to the ratio between the value of the three standard deviations of positive and negative and the range close to the true value, which refers to the maximum difference between the measured value and the true value; resolution - is the minimum measured value that causes the indicated value to change; Separated from the effective coefficient (effective coefficient - the ratio of output to input) The accuracy of the general household temperature sensor is divided into two levels, A and B. The national standard specifies as follows: The difference between the sensor output value and the actual measured temperature is differentiated. Class A: no more than + (0.15 ° C + 0.002 * sensor range); Class B: no more than (0.30 ° C + 0.005 * sensor range). Therefore, if the measurement accuracy is required to be high, a sensor with a small range should be selected. The resolution "usually depends on the number of bits in the analog-to-digital converter" or the last bit of its output value.

Resolution
Concept: The ability of a sensor to perceive the smallest change measured. That is, if the input amount changes slowly from some non-zero value. When the input change value does not exceed a certain value, the output of the sensor will not change, that is, the change of the sensor's input amount is not discernible. The output will only change when the input changes more than the resolution. The resolution is generally understood as the A/D conversion accuracy and the perceived minimum change. The accuracy generally refers to the integrated elements such as A/D and other elements of the sensor circuit, and is divided in the proportion of errors. The appearance of the number Generally speaking, the digit accuracy of the A/D converter is the maximum percentage of the same reference value measured by the sensor, and the target resolution for measuring the corrected accuracy is several times or more the accuracy. In general, the resolution of the sensor at various points in the full-scale range is not the same. thus. A large change in the input quantity that causes the supply to produce a step change in the full-scale range is considered as the overall goal of considering the resolution.