Introduction to mounting accuracy, precision, and resolution

Measurement uses accuracy, precision, and accuracy to evaluate and measure the quality of measurement results. The three terms are often confusing and their meanings are different.

· Accuracy-indicates the degree of consistency between the measurement result and the measured (agreed) true value, sometimes referred to as accuracy,

Reflects the degree of system error in the measurement results. High Accuracy means that the system error is small. At this time, the average value of the measurement data is less than the true value, but the data is scattered, that is, the size of the repetition error is not clear.

· Precision-the degree of conformity between the measured results after multiple measurements, also known as repetition accuracy, indicates the degree of repetition error in the measurement results. High Precision means that the error of repetition is small. At this time, the measurement data is concentrated, but the size of the system error is not clear.

· Precision-a comprehensive indicator of accuracy and precision, sometimes referred to as precision, but it is easy to be confused with precision. High Accuracy means that the repetition error and system error are relatively small, and the measurement data is concentrated near the true value.

Figure 1 illustrates the meaning of the three words mentioned above when a dart is used as an example. The target value position is represented by the target. Figures 1 (a) and (B) Indicate the good and bad shooting accuracy, that is, the system error size. Figures 1 (c) and (d) it indicates the precision and difference of the shooting, that is, the size of the repetition error. Figure 1 (e) shows that the precision and accuracy are good, which is called high accuracy, at this time, the system error and repetition error are both relatively small.

 

Figure 1 accuracy, precision, and accuracy

(2) Resolution and resolution

There are two common definitions of resolution: one is the minimum resolution limit for an instrument, instrument, or tool device to distinguish objects. For example, the minimum moving distance (CM, mm, μm and nm), the current voltage (mV, μV, Ma and μA) of the electronic meter, and the second is the display image device (such as the display and scanner) number of points or lines that can be distinguished within the unit length. Common units include DPI and LPI ", "SPI" and "PPI" [that is, the number of points (lines, samples, pixels) per inch] or "DP, LP, SP, and PP)/Imm ", [points per millimeter (line, sample, number of workers.

Resolution is short for "resolution ability" (or "resolution ability"). Generally, "resolution" is only high or low, and the quantitative result of resolution is called "resolution ". However, in practical applications, "resolution" and "resolution" are often used in a general sense.

(3) accuracy and resolution

Accuracy and resolution are often used in measuring performance indicators of various instruments as parameters of accuracy. However, resolution and accuracy are not necessarily correlated, and high resolution is only the foundation of high precision. The high resolution of a device is only a required condition for high precision, not a sufficient condition, but not a sufficient condition.

(4) accuracy, precision and accuracy of mechanical equipment

In mechanical equipment, precision and repetition are used to evaluate the accuracy of machine positioning and processing. However, at different times, the meaning of "precision" is different: when we discuss "precision" and "repetition precision", "precision" refers to the "accuracy" of measurement, and "repetition precision" refers to the "precision" of measurement "; in general, Machine "precision" refers to the "precision" of measurement ". The placement machine is a processing machinery and equipment, and people's title is the same. Although it is not scientific, it becomes natural and cannot be changed at the moment.

It is obvious that the definition and title of Measurement on accuracy, precision, and accuracy are more scientific. In fact, the same name as surveying has already been used in the teaching and research of placement machine technology, but people have to consider it as a habit. However, with the development and improvement of technology, especially the promotion and application of general international standards, for example, regarding the application of the Process Capacity Index CP and CPK of the placement machine, the unification of names and the concept should be clearly understood.