| Precision seeding has gradually become the main development direction of Sowing Technology and the automatic control system of electronic technology has been widely used in precision seeding industry.Domestic research behind many in this area compared to foreign,but after many years’ efforts,we have achieved certain results.So many other research of precision seeding focused on the mechanical sowing machine parameter optimization and has achieved certain results,but it does not solve the leakage phenomenon caused by the ground wheel slip and so on.And most of the research on control system in China is focused on monitoring the leakage,replay and fault alarm,etc.Many of the research on the seeding system is based on the measurement of the speed of the tractor,which is based on the foundation of the ground wheel.In view of the above problems,this paper took STM32 processor as the control core,applicated the speed radar to measure the working speed of tractor,used the brushless DC motor as the power source,which made rational speed of the seed metering device and the tractor’s speed synchronization,improve the precision of discharge and realized the plant spacing to regulated easily.The specific research contents are as follows:(1)This paper took the vertical spoon wheel seed metering device as the research object,analyzed the main structure and operating parameters.Used the EDEM software to do discrete element simulation.At the same time,it was concluded that when the angle of the start delivery was 2 degrees,11 degrees and 20 degrees,and the speed of the seed metering device was min/46.26 r,the capability of seeding mechanism is the best;when the angle of the start delivery was 29 degrees and 38 degrees,and the speed of the seed metering device was min/02.34 r,the capability of seeding mechanism is the best,which provided some reference to the research of the spoon wheel seeding metering device and some comparison compared to the field experiment of control system.(2)Analyzed the main factors which affected the quality of sowing:the land wheel slipping,type of the seed metering device and release height.Then put forward the corresponding measures for each factor and proposed the general design scheme finally.(3)According to the general design scheme,then carried out the hardware designed and software designed.The hardware design mainly had five parts:data acquisition module,actuator control module,human-computer interaction module,power supply and signal conditioning module and anti-interference technology for hardware.The software design mainly had two parts:the main program and subroutine,then each part was analyzed from the control flow chart and the procedure main code.(4)Field experiments were conducted on the control system,and the results showed that:when the tractor run in the stable stage,the average error is 8.02%,the minimum is2.23%,and had high control precision;in each driving condition,when the tractor run in the speed of 8km/h < v ≤ 10km/h,it had the best stability and the minimum error is 0,the maximum error is 6.42%;the qualified index and coefficient of variation had the best effect under different start delivery angle were all in low speed,high speed and low to high speed,which qualified index was more than 87.9% and the variation coefficient was less than 0.42.But when the tractor run at high speed(≥10km/h),it had poor sowing effect and there was a great difference between the qualified index and coefficient of variation of plant spacing.Compared with the non control system of bench test,the control system improved the sowing quality and easily control the plant spacing. |
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