Research On Quantitative Combination Weighing Control System For Non-uniform Materials

Combination weighing quantitative technology is currently an advanced quantitative method,which is widely used in bulk materials,and the technology is becoming more mature.However,it is relatively less used in heterogeneous materials.The single weight of this type of material is large and different,but The weight follows a normal distribution.This article takes the combination of fruit non-homogeneous material combination weighing and quantification as the object,based on the chain cycle combination weighing and quantitative device,according to the characteristics of the non-homogeneous material and combination weighing quantitative requirements,analyzes the functional requirements of the control system;explores the combination The source,influencing factors and changing laws of weighing error are analyzed,and the combined error is optimized and analyzed;the embedded single-chip control system architecture is designed,the software and hardware of the control system are modularized,and the function of the control system is verified.The main contents and conclusions of this paper are as follows:1)In view of the large difference in the single weight of heterogeneous materials and the indivisible characteristics,based on the chain combination weighing and quantitative machine,it is clear that the main function of the control system is to perform combined weighing and output of heterogeneous materials,and complete the alignment Analysis of other functional requirements of the system.2)Aiming at the contradiction between high quantitative accuracy and fast combination speed in the combination of non-uniform material quantitative combination weighing technology.Based on the chain combination weighing and quantitative system,it is proposed to optimize the number of combined samples and the number of samples with the goal of quantitative accuracy and combination efficiency.To achieve the purpose of reducing the amount of data calculation under the guarantee of the combined weighing quantification accuracy to improve the combined quantification speed.Research shows that under the same allowable combination error,increasing the number of combination samples can increase the probability of combination success,but the amount of combination calculation increases exponentially as the number of combination samples increases.By performing 10 000 rounds of combination calculations on the weight data that obey the normal distribution N(100,102),it is found that when the combined quantitative target weight is 500 g and the allowable combination error is±0.1 g,the number of combined samples with a shorter calculation time It is 14;when the allowable combination error is±0.05 g,in order to ensure the success probability of the combination,the number of combination samples should be 16 and above.In addition,the chain combination weighing quantitative test verification was carried out to optimize the combination algorithm of the number of samples and the number of samples.The test results show that when the material weight standard deviation is less than or equal to 30 g and the allowable quantitative combination error is 0.1 g,the optimized combination algorithm and the pre-optimized traversal combination algorithm maintain the overall success probability of quantitative combination at about 95%,and the optimized combination algorithm The calculation time of the algorithm combination is reduced by 40%.3)Research on control system hardware.According to the functional requirements of the control system,the overall framework of the control system was clarified;the selection of key components including touch screens,actuators,and sensors was determined;the core hardware controller circuit of the system was designed,and the rationality of the circuit design and PCB layout and wiring It is related to the selection of key components.The core circuit of the controller mainly includes the STM minimum system module,communication module,16-channel optocoupler isolation drive module,information acquisition module,and power supply module.Finally,the PCB and controller box design are completed.4)Control system software design.In order to ensure the stability and rapidity of system functions,and enhance the maintainability of the program,the program is developed with a design idea of high cohesion and low coupling.The software mainly includes modbus communication,information acquisition program,average median filter algorithm,combined quantitative algorithm design and human-computer interaction interface development.Finally,the software and hardware control system is debugged and tested in combination with the test platform to realize combined weighing and quantitative functions,so that the system meets the control requirements.