As a key component of weighing instruments, the load cell is a kind of
A device that converts a mass signal into a measurable electrical signal output, which
The accuracy and stability of performance directly affect the reliability of the measurement results
Sex. To ensure the measurement accuracy of weighing instruments, it is necessary to conduct tests before use
Row calibration, that is, determining the input-output characteristic relationship of the sensor. "Tradition"
The calibration method is to apply a known mass to the weighing instrument using standard weights
Load, simultaneously record the output signal of the sensor, and process the data
Obtain the calibration curve and parameters of the sensor. However, this method exists
There are many drawbacks, such as the need for a large number of standard weights and the complex calibration process
It is complex, has a long cycle, and high costs. Moreover, for some installations at heights,
Loading of weights for weighing instruments in special positions such as underground and large equipment
It is extremely difficult or even impossible to uninstall. Therefore, no weights are required
The determination of methods has become an important topic in the field of weighing instrument research. 
1
Overview of the weight-free calibration Method
The principle of weightless calibration is mainly based on mathematical models and algorithm optimization
By means and methods such as optimization, reference standard substitution, and multi-parameter fusion, the results were obtained
By taking the characteristics and laws of the measuring equipment, the calibration of the weighing instrument can be achieved
During the process, traditional standard weights are not used as the loading mass, but rather through
Simulate the mass load by other means or methods, or utilize the relevant
The principle, algorithm and equipment establish the input and output of the load cell
The corresponding relationship is achieved to reach the purpose of calibration.
1.1
Mathematical model and algorithm optimization
Establish an accurate mathematical model of the sensor and take into account the object of the sensor
Factors such as physical characteristics, structural parameters and working environment. Through these
Analysis and modeling of factors to predict sensors under different input conditions
The output. By applying advanced optimization algorithms, such as the least square method
Kalman filtering and other methods are used to precisely estimate and adjust the parameters in the model
To improve the accuracy of calibration.
1.2
Reference standard substitution
Use high-precision known physical quantities or standard signals as parameters
Take the exam and replace the traditional weights. For example, using a stable voltage source
Calibrate the relevant measuring equipment with a current source or standard frequency signal. or
The output is based on the calibrated high-precision sensor of the same type as the reference
The test involves comparing and calibrating the sensors to be calibrated.
1.3
Multi-parameter fusion
Comprehensively consider multiple parameters related to measurement, not just rely on them
For a single physical quantity. For example, in the calibration of load cells,
At the same time, factors such as the position of the force application point and the loading speed should be considered for the measurement results
The influence. By integrating the information of multiple parameters, a more comprehensive approach is established
And an accurate calibration model.
Of course, weightless calibration also takes advantage of having known accurate characteristics
1
Use physical objects instead of weights, or complete it through various compensations and other means
The calibration process is completed.
2. Application of the calibration method without weights
The weight-free calibration method is widely and significantly used in many fields
The application, for example, when a large number of physical standard weights cannot be achieved or when it is necessary
In cases where a large number of weights need to be frequently used for calibration, such as in hopper scales and electrical systems
It is applied in various places such as truck scales and non-standard weighing instruments. The following is this method
Here are a few cases of application in actual work:
Calibration of the hopper scale
Hopper scales are used in industrial production batching, logistics control and cost accounting
It plays a crucial role in the daily calibration and weighing accuracy
The degree will directly affect the stable operation of production and the quality of products. These demonstrate the application of weightless calibration technology in various scenarios
It provides solutions to the problems of difficult use or inconvenient calibration of weights
An effective solution has enhanced work efficiency and reduced costs.
However, it should be noted that the accuracy and reliability of the weightless calibration technology
Sex may be influenced by various factors. In practical applications, one should
Conduct assessment and verification based on specific circumstances, and follow relevant norms and regulations
An operation is required.
The advantages and disadvantages of the weight-free calibration method
The advantages of the weight-free calibration technology include
(1) Save costs. For some that are difficult or impossible to deliver 砝
In such situations, the high cost of using a large number of weights for calibration can be avoided
Use.
(2) It is easy to operate, saving time and labor costs. No weights required
The calibration method does not require the transportation and use of a large number of weights, reducing the need for calibration
The operation steps and workload during the calibration process have been determined, improving the calibration efficiency.
(3) It has a wide range of applications and can solve the problem of difficult calibration in special occasions
topic. For example, weighing in high-level silos, narrow Spaces or complex environments
If the weights are difficult to position or cannot be placed, no weight calibration is required. Provided
A feasible calibration method has been obtained.
3.2 The weight-free calibration technology also has some shortcomings
(1) Currently, its persuasiveness and recognition in the industry are limited. Because
Its calibration mainly relies on the factory calibration data of the load cell and is ignored
Due to the errors in the mechanical force transmission structure system, it is difficult to conduct a comparison test with weights
The validity of the certificate is often questioned and it is difficult to obtain it from non-metrological verifiers
The general recognition of the staff.
(2) High requirements are placed on weighing instruments and sensors. A scale that requires the configuration of weighing instruments
The heavy sensor has a sufficiently high accuracy, good stability and reliability
The division number must be greater than or equal to that of the weighing instrument and must also be accompanied by a technical unit
A formal calibration test report with complete technical parameters. Meanwhile, the force transmission of the weighing instrument
The structure should be simple and standardized connecting components should be adopted to ensure the weight of the materials
Accurately transmit to the load cell, and the no-load zero point of the weighing instrument needs to be stable.
(3) Calibration accuracy may be limited. Different weightless calibrations
The calibration accuracy of the methods and systems varies. Simulated weighing system
The calibration accuracy without weights is generally 0.5% to 1.0%, and it is digital weighing
The calibration accuracy of the system without weights is usually 0.4% to 0.1%[4].
In practical applications, the pros and cons should be weighed based on specific circumstances
Under the premise of meeting the calibration requirements, make a reasonable choice as to whether to adopt the weight-free method
Calibration technology. At the same time, it is necessary to pay attention to following relevant norms and requirements
Operate to ensure the accuracy and reliability of calibration. If conditions permit
If possible, physical comparison tests can be conducted as much as possible for verification to increase the calibration ratio
The credibility of the fruit.