Several Reasons for Weighing Errors of Electronic Platform Scales
August 17,2022
The error of the electronic platform scale is a quantitative description of the accuracy of the weighing result. Analyzing the weighing performance of an electronic bench scale and understanding the source of errors will help improve the quality and efficiency of the verification work of the electronic scale.
The electronic platform scale is mainly composed of a weighing platform, a load cell, a junction box, a shielded signal cable, and a weighing display instrument. Put the object to be weighed on the weighing platform, under the action of gravity, the weighing platform transmits the gravity to the load cell, the sensor deforms the elastic body of the sensor, and under the action of the excitation voltage, the output is proportional to the mass value. voltage signal. The signal is amplified by a linear amplifier and then converted to a digital signal by A/D, and the quality signal is processed by a microprocessor.
- Error analysis, weighing, identification, and repeatability of the four corners of the electronic platform scale
Four-corner eccentric load error The eccentric load test requires that after the electronic platform scale is loaded, changes in the position of the measured weight on the weighing platform should not cause changes in the weighing measurement results. Therefore, the four-corner eccentric load error comes from the sensitivity of the load cell. Differences in key materials such as elastomers and resistance strain gauges of electronic platform scale load cells, as well as imperfect manufacturing processes, the absolute sensitivity of each load cell are different, resulting in the same excitation voltage, and the signal output of each load cell is different, resulting in a four-corner unloading error. To reduce the four-corner unloading error, the electronic platform scale is connected to a potentiometer in each sensor branch. You can adjust the resistor values and use different voltage dividers for different resistors to balance each signal output of the branch.
- Zero drift and weighing platform friction are the direct causes of weighing errors
(1) Linear change of weighing sensor Due to the influence of temperature difference, impact force, floating dust, etc., the load on the sensor is not in a linear relationship with its corresponding output voltage, which makes the weighing linearity of the sensor possible. Electronic platform scale sensors vary widely. Sometimes the error of the weighing point of the parts is relatively large, and the linear calibration of the weighing is carried out, that is to say, the weighing of the electronic platform scale is calibrated in sections, and the relative error of the weighing will be greatly reduced.
(2) During use, the "zero drift" electronic platform scale is affected by different sizes and multiple reciprocating impact loads. The force of the sensor is very complex, which eventually causes the contact of the sensor to change, which changes the original state of the verification, resulting in zero drift and error.
(3) Friction depends on the transmission of influence so that the weight during loading cannot fully act on the load cell, and the output signal of the load cell is naturally small. In this case, a small weight is usually normal, and as the load is increased, the displayed value decreases considerably.
To ensure the accuracy and reliability of the measurement of the electronic platform scale, it is inevitable to debug the weighing performance of the electronic platform scale. Knowing the source of the error can greatly help us in our actual work and facilitate the user. Electronic bench scales are not only widely used in commercial measurement, but with the development of the economy, more and more electronic bench scales are used in the production process. This paper mainly analyzes the error sources of electronic platform scales, to improve the efficiency of verification and debugging of electronic platform scales, which is helpful to users who use electronic platform scales.
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