Design Of Weighing System For Facility Agriculture Fruit And Vegetable Transporter Based On STM32

Facility agriculture is an important branch of my country’s agricultural development.The picking and transportation process of agricultural products is time-consuming and laborious and the collected output information is easy to lose.In response to these problems,this thesis designs a fruit and vegetable transporter weighing system based on STM32.The weighing system is mounted on an ordinary transporter,so that the transporter has a weighing system.Function to achieve the purpose of transportation and weighing integration.The weighing system has a GPRS module that can connect to the cloud platform.This module can upload the weighing information of fruits and vegetables to the cloud platform and collect the output information of fruits and vegetables.This system provides necessary data support for the establishment of smart agriculture.The specific research content of this paper is as follows:Starting from actual needs,STM32F103 single-chip microcomputer is selected as the main controller module of the weighing system,and four YCD-100 Kg resistance strain pressure sensors jointly sense the force load signal of the weighing platform.The four resistance strain pressure sensors are connected in the way of output digital summation,and the voltage signal output by the load cell is converted into the corresponding digital signal by the four HX711 A/D conversion modules.The JY901 attitude angle sensor is used to correct the inclination error in the weighing process,the active buzzer constitutes an overweight alarm circuit,the SD card is used as the local storage medium,and the GPRS+GPS two-in-one Air800 module completes the geographic coordinate positioning and positioning of the fruit and vegetable production area.The cloud platform uploads fruit and vegetable weighing information,and the resistive touch screen completes the humancomputer interaction function.The 24 V DC power supply of the transport vehicle is supplied to the electrical components in the system through the LM2596S step-down module.Because the system uses four load cells,the online calibration technology of multiple load cells has become one of the key issues in this design research.Aiming at the commonly used digital sum calibration method,the ill-posed problem is often encountered during the calibration process,which causes the poor stability of the calibration result.From the perspective of solving the ill-conditioned calibration equation,the least square method is analyzed to solve the ill-posed problem.Based on the limitation of time,by analyzing the relationship between the condition number of the calibration equation design matrix and the ill-posed problem,from the perspective of avoiding the ill-posed problem,a digital sum calibration method based on the minimization of the condition number is proposed.This method can make the condition number of the design matrix of the calibration equations close to the minimum without losing any information,thereby improving the calibration accuracy while ensuring the stability of the calibration.After the effectiveness of the method was proved by simulation experiments,the method was used to complete the on-site calibration of four load cells,and 4 sets of weights of different weights were used,and each set of weights was randomly placed at any position of the weighing platform for measurement 10 Second,the calibration results were tested.The maximum absolute error was 0.03 kg,and the maximum percentage error was 0.40%.The test results proved the correctness and effectiveness of the weighing system calibration using the digital summation method with the minimum condition number.For the problem that the waveform of the weighing sample signal is unstable and affects the weighing accuracy,the software method is used for digital filtering.Through the analysis of common filtering algorithms,it is determined that the combination of inertial filtering and sliding average filtering is used to form the weighing system.Digital filter.Through multiple experiments and comparing the experimental results to determine the filter parameters of the filter,after combining the filter effect and the delay generated by the filter,it is finally determined that the inertial filter output result with the filter coefficient α=0.4 is recursively used as the three-time sliding window length The digital filtering is completed by the sliding average filtering method of 3,which can control the weighing accuracy within ±0.05 kg within 1s.The STM32 embedded program was developed in the keil5 environment.Completed the software design of the resistive touch screen human-computer interaction module in the US ART HMI environment.In actual application scenarios,the weighing system works well and can accurately complete the system’s preset functions.