What are the measurement methods of laser ranging sensors

In daily work, people are not very comprehensive about understanding methods, so what are the methods? Let me explain to you the method, which is the specific method taken by the sensor.

The measurement method is very important to the detection system, and it is directly related to whether the detection task can be successfully completed. Therefore, it is necessary to analyze different detection purposes and specific conditions, and then find a practical measurement method, and then select the appropriate detection technology tools according to the measurement method to form a complete detection system for actual measurement. For measurement methods, from different perspectives, there can be different classification methods.

According to the classification of measurement methods, there are: direct measurement, indirect measurement and combined measurement; according to the measurement method, there are: deviation measurement, zero measurement and differential measurement; according to the accuracy of measurement, there are: equal precision measurement and non-precision measurement. Equal precision measurement;

Classified according to the change of the measured, there are: static measurement and dynamic measurement; according to whether the sensitive element is in contact with the measured medium, there are: and etc.

（1） Direct measurement

When using for measurement, the meter reading does not need to undergo any calculations, and it can directly indicate the result required for the measurement, which is called direct measurement. For example, measuring the current of a circuit with a magnetoelectric meter, and measuring the pressure of a boiler with a spring tube pressure gauge are direct measurements. The advantage of direct measurement is that the measurement process is simple and fast, but the disadvantage is that the measurement accuracy is not easy to achieve high. This measurement method is widely used in engineering.

(2) Indirect measurement

Some measured values cannot or are inconvenient for direct measurement. This requires that when using the meter to measure, first measure several quantities that have a definite functional relationship with the measured physical quantity, and then substitute the measured value into the functional relationship, and then calculate it. The desired result, this method is called indirect measurement. For example, if you want to measure the density ρ of a cuboid, the unit is kg/m3. Obviously, it is impossible to directly obtain the value of this unit. However, you can first measure the length, width and height of the cuboid, namely a, b, c (unit Is m) and its mass m (unit: kg), and then obtain the density according to the following formula:

Indirect measurement requires more measurement than direct measurement, and the calculation process is complicated, and there are more factors that cause errors. However, if the error is analyzed and the optimized measurement method is selected and determined, indirect measurement is performed under ideal conditions. , The accuracy of the measurement results is not necessarily low, and sometimes higher measurement accuracy can be obtained. Indirect measurement is generally used in occasions where direct measurement is inconvenient or lack of direct measurement means.

(3) Combined measurement (also known as simultaneous measurement)

In the application of sensor instruments for measurement, if the measured physical quantity must be solved by solving the simultaneous equations to get the result, then such measurement is called combined measurement. When performing combined measurement, it is generally necessary to change the test conditions to obtain the data required by a set of simultaneous equations.

Combined with a special precision measurement method, the operation procedures are more complicated, and it takes a long time. It is generally suitable for scientific experiments or special occasions.

Deviation measurement, zero measurement and differential measurement

Use the displacement (ie deviation) of the pointer of the meter to determine the measured value. This measurement method is called deviation measurement. When using deviation measurement, the scale of the meter is calibrated with standard instruments in advance. When measuring, input the measured value, and determine the measured value according to the value indicated by the indicator on the scale. The measurement process of this method is relatively simple and rapid, but the accuracy of the measurement results is low.

Zero-position measurement is a measurement method in which the zero position of the zero-pointing instrument is used to indicate the balance state of the detection measurement system. When the measurement system is balanced, a known standard quantity is used to determine the measurement value of the measured value. When using this measurement method to measure, the known standard quantity is directly compared with the measured quantity, the known quantity should be continuous, and when the zero-pointing instrument is pointing, the measured quantity is equal to the known standard quantity. For example, balances, potentiometers, etc. The advantage of zero-position measurement is that it can obtain relatively high measurement accuracy, but the measurement process is more complicated, and the measurement needs to be balanced, which takes a long time and is not suitable for measuring fast-changing signals.

Differential measurement is a measurement method that combines the advantages of deviation measurement and zero measurement. It compares the measured value with the known standard quantity, and after the difference is obtained, the difference is measured by the deviation method. Therefore, this method has the advantages of fast response and high measurement accuracy, which is especially suitable for online control parameter measurement.

3" Equal accuracy measurement and non-equal accuracy measurement

In the whole measurement process, if all the factors (conditions) that affect and determine the measurement accuracy remain unchanged, such as using the same instrument, using the same method, and under the same environmental conditions, perform multiple repeated measurements on the same measurement. , Called equal precision measurement. In practice, it is difficult to keep all these factors (conditions) constant at all times.

Therefore, in general, it is only approximated as an equal-precision measurement. Using different precision instruments or different measurement methods, or in the case of large differences in environmental conditions, to carry out multiple repeated measurements on the same measured object is called non-equal precision measurement.

4" Static measurement and dynamic measurement

is considered to be fixed during the measurement process, this kind of measurement is called static measurement. The static measurement does not need to consider the influence of the time factor on the measurement.

If the measurement is constantly changing with time during the measurement process, this measurement is called dynamic measurement.

In the actual measurement process, we must proceed from the specific situation of the measurement task, and after careful analysis, decide which measurement method to use.