Design And Research On Testing And Digital Compensation System Of Load Cell

The purpose of this study is to develop a cost-effective digital weighing system by establishing a mathematical model of error that restricts the accuracy of load cells and implementing filters and compensations based on hardware and firmware,which would help to improve the overall performance of the Load Cells.In addition,it will put forward a solution for manufacturer concerning calculation of load cell compensation parameters and qualification for the industrialization by designing an upper PC software.This study is mainly to explain how to design a digital weighing system with the accuracy of higher than 5000 intervals systematically from four aspects,which contains testing technology for high precision digital load cell,design for hardware of high precision A/D board,digital filter and compensation development for firmware as well as the development of PC application software.Firstly,build up a testing platform by analyzing requirements of high precision digital load cell and then introduce the load cell testing technology and principle.Secondly,the design of hardware circuit board applies high precision applies 24-bit analog-to-digital convertor ADS1232 and STM microcomputer.It also discusses the anti-interference design of hardware and the solution to fix the issue of the ADC.Thirdly,there is a verification to analyze the type and distribution of the noise collecting from ADS1232.Then,a design of two-stage filter model of moving average and Kalman predictive-correction is to process the raw data in MCU.The optimal process parameters Q and measurement parameters R are determined by combining efforts of simulation and experiment to ensure that the dynamic response characteristics can be kept as far as possible when the steady state performance is better.Moreover,it explains how to design the MCU's software compensation scheme for A/D board by analyzing the mathematical error model.In the last chapter,it introduces a parameter calculation tool of the upper computer based on MATLAB,which can perform matrix operation with the collected data,fit the nonlinear and temperature compensation parameters by the optimal square approximation,and evaluate the conformity of the actual performance after performing compensation on load cells.