A Research On Crop Seeds Automatic Weighing System

Scientific research shows that the range of seed weight distribution is an important indicator to evaluate the seed quality. Measuring the weight spectral distribution need to measure each seed weight, count the number of seeds in each interval, and then draw the weight spectrum. In order to free researchers from this tedious, time-consuming and strenuous work, this paper intends to study the automatic weighing system of crop seeds, and design a automatic weighing system for wheat seed. The system consists of the automatic transmission mechanism and automatic weighing platform. The automatic transmission mechanism put seeds single; realize single seed down and automatic seed removing. The automatic weighing platform acquires and process signal from sensors, realize seeds weight identify, counting and weight spectral distribution graph drawing.The main work and results can be summarized as follows:(1) Research and design a wheat seed automatic deliver device based on shaped hole plate seed-metering device, this deliver device will put sum seeds single. Slabs are install to "shaped hole plate" shaft, to remove seed from weigh platform automatically.(2) In order to adjust seeds transmission speed, design and manufacture rotation rate adjust, control, drive circuit. This circuit consists of step pulse generator, Ring distributor L297, power driver L298. The step pulse generator is a Schmidt trigger which based on "555" the output frequency is adjustable.(3) Data acquire and transforming circuit is designed. This circuit is made up of24bit analog to digital convertor (ADC) AD7191and STC89C52microcontroller. The microcontroller read data from ADC, and use RS232to send data package to computer serial port, the purpose of designing data package is to make the upper computer distinguish data accurately.(4) Data processing method is studied. Such as mean filter, Kalman filter, digital filter, wavelet denoising. The results show mean filter, Kalman filter are most suitable for weighing data processing.(5) Automatic weighing software is compiled based on Virtual Instrument software Labview. The weighing software read data from serial port, distinguish data in the data package, after data processing, sampling value is changed to weight value, and display weight value in the user window, and this software will draw weight spectral distribution graph.The results show that:the step motor control module can meet the actual speed control needs. Dynamic weighing process shows that:automatic weighing platform works well, and the automatic weighing software can measure the seed weight, count the seed number, display the results and draw the weight spectrum effectively. The minimum division of static weighing and automatic weighing is2mg and3mg, respectively.