The Design And Development Of High-accuracy Digital Load Sensor System

This paper deals with designing of digital load cell censor system whichfeatures high accuracy and low sensitivity to noise. The traditional analog-digitalconversion weigh scale has problems that it cannot used by a long-distance signaltransfer and low accuracy of it. What’s more, the traditional load cell system islow accuracy and not convenient at all. This design aims to solve these problemsand limitations so that the accuracy and long-distance features will no longer be aproblem. By porting a digital filter and all system to chip based on ARMcortex-M3, the cost and stability and accuracy of the whole system has beenimproved.Designed with the real-time operation system RT-Thread, the whole systemcan be developed as each single part like ADC drivers’ part, FIR filter part, andthe UI part. As we can see, the most important part is the ADC and FIR filter, so,this paper will ignore the other parts like UI and communication protocol, whichis quite easy by applying RT-Thread drivers and relevant protocol likeFreeMODBUS.Chapter one reviews the main principles and development trends of currentload cell sensor system, introduces the background knowledge of signalprocessing. Chapter two describes the whole project case including softwaredesign and hardware device selection. Chapter three is mainly about how theADC part is designed and process of how we designed like this. And then weshow how the ADS1251work and the design of the driver of ADS1251and themicro-controller on STM32. Chapter four illustrate the theory of the FIR iflterand then give the most popular way of how to design an FIR filter by Matlab.After Chapter four, we ported the FIR structure on Cortex-M3device and showthe result of FIR filter.