Research And Development Of Control System For Combined Weighing Devices

With the rapid development of electronic information technology,the level of industrial automation and the gradual progress of enterprise information management technology,the traditional single-package weighing scales in the food packaging industry consume time when weighing objects with irregular shapes and non-uniform quality.However,it is difficult to count the number of packaging products in unit time,and the production cost is high.In addition,it is increasing difficult to meet the requirements of the company's production,and the concept of combinatorial weighing is a good solution to this problem.The combination weigher adopts the combination weighing principle and combines with the database technology.It has the features of fast weighing speed,high measurement accuracy,and easy storage and management of data.It reduces the labor intensity of workers,effectively reduces the production cost of the company,and improves production.The degree of speed and information management has greatly enhanced the company's core competitiveness.Therefore,more and more companies choose combination scales for product packaging.The performance of the combined weigher control system will directly affect the stability of the performance of a combined weigher.Therefore,the research of the weigher control system is very important.This topic starts from the principle of combination weighing,uses the theory of mathematical statistics to perform probabilistic statistical analysis on the algorithm of the combination scale.And the database technology plays an important role in managing the production information.The ultimate purpose is to design a set of combinational scales with convenient information management and high automation level.Control System.The control system designed in this paper,which uses the main controller and the sub-controller to control the operation of the combination weigher.The CPUs of the main and sub controllers all use the STM32F103ZET6 chip that produced by STMicroelectronics.The main controller is used for material position detection,calculation of combinational algorithms,driving of stepping motors,and data exchange with the host computer.The secondary controller is responsible for the signal acquisition of the load cell,scale conversion,and transmission of the material weight value to the main controller.Among them,the AD7609 chip of 18-bit successive approximation analog-to-digital converter is used for AD conversion,and the 8-channel signals are all differential inputs.At the same time,the multiple channels also can be sampled,and the sampling rate of each channel can reach 200 KSPS.The PC as a host computer and the use of VisulStudio2015 to compile the upper computer operation interface for parameter setting and human-machine interaction,the upper and lower position machine based on LoRa remote wireless serial port to follow MODBUS protocol for communication.The SQLServer2014 database was used to store the information of the combined scales for information management.The control system hardware of the combination scale mainly includes load cell,AD7069 analog-to-digital converter,main and sub controllers with STM32F103ZET6 chip as the core,LoRa remote wireless module,PC upper computer,stepper motor and driver,and DC power supply module.On the basis of these hardwares,the lower computer control program,the upper computer man-machine interaction interface,and the database list are written according to the system requirements.The control system finally succeeded in achieving the automatic control and information management of the combination scale.