Design And Experiment Of The Wheat Variable Seeding System Based On GPS And Encoder

Sowing plays an important role in the process of wheat planting and production,and its operation quality affects the growth of wheat,which will affect the yield of wheat.When the traditional mechanical wheat planter is working,it is generally the ground wheel or chain to provide power for the seed metering device.When the working speed of the wheat planter is high,it is easy to appear chain beating,ground wheel slipping and so on,which causes the phenomenon of missed sowing and less sowing,and the sowing quality is not effectively guaranteed.Moreover,when the tractor is just starting to work or fast to the ground,the seeding operation speed will be significantly slower than the normal operation speed.At this time,if only GPS or encoder speed measurement can not really guarantee the uniformity of seeding.In view of the above situation,this paper designs a wheat variable seeding control system based on GPS and encoder speed measurement.The main research results and conclusions are as follows :(1)Overall design of wheat planting platform.Through the study of the technical parameters,structural composition,sowing method and working principle of the traditional wheat seeder,the working scheme of replacing the ground wheel drive sowing with a DC brushless motor was determined.It is mainly composed of Arduino Mega microcontroller,DC brushless motor,DC brushless motor driver,GPS speed measurement module,photoelectric encoder,mobile phone terminal,HC05 Bluetooth module,Taojingchi serial screen,seed metering device and fertilizer discharge device.(2)Design of wheat seeding platform speed measurement system.Through the performance analysis and research of different speed components,the GPS speed measurement module and the photoelectric encoder speed measurement module are finally selected.The accuracy of GPS speed measurement error was 0.15km/h.The actual speed of the photoelectric encoder speed measurement module was compared with the theoretical speed,and the accuracy of the speed measurement error was 0.2km/h.The GPS module and the speed signal collected by the photoelectric encoder are fused to obtain a more accurate speed signal,which lays a good foundation for the driving work of the metering device.(3)Human-computer interaction terminal design.In order to facilitate the operation of the system and the display of the real-time state of the machine,this study uses the Taojingchi serial screen as the display terminal of human-computer interaction,and the serial screen communicates with the main controller.When the seeding platform starts to work,the serial port screen can display the current operation location information,operation speed,driving distance,operation area and seed remaining amount in the seed box in real time.(4)Control system outdoor test.The comparison test of GPS and encoder was carried out under the condition of 5 kinds of operation speed(1,3,5,7,9km/h)and 5 lines of operation.The test results show that when the seeding platform was operating at a speed of 1km/h,the variation coefficient of the seeding uniformity of the encoder was 6.06 % higher than that of the GPS speed measurement.When the forward speed of the seeding platform was increased to 9km/h,the seeding uniformity coefficient of the GPS speed measurement was 2.77% higher than that of the encoder speed measurement.It shows that GPS speed measurement was more suitable for highspeed operation,while photoelectric encoder speed measurement was better in low-speed operation.The wheat seeding platform equipped with GPS and encoder dual speed measurement system,compared with the traditional wheat planter uniformity coefficient of variation standard5%,the seeding uniformity coefficient of variation is below 3.5%.