基于PID算法的气力式施肥机变量施肥控制系统设计与试验

Design and Test of Pneumatic Fertilizer Applicator Variable Ratio Fertilization Control System Based on PID Algorithm

中国南方的粮食作物以水稻为主,在水稻的种植过程中经常需要根据水稻生长情况进行追肥作业,目前常用的离心圆盘式撒肥机虽然提高了追肥作业的效率,但难以保证施肥精度以及幅宽方向的施肥均匀性,并且目前大多数研究的变量施肥控制系统主要以旱田的变量施肥控制为主,对适用于水稻追肥作业的变量施肥控制系统的研究较为缺乏。针对上述问题,设计了一种基于气力式施肥机与PID控制算法的变量施肥控制系统,该系统与高地隙拖拉机配合使用,主要适用于稻田变量追肥作业。其中以STM32F103芯片为核心,开发了变量施肥控制器;采用增量式PID算法实现了对排肥电机转速的闭环控制;以中海达公司的Qpad-X5为硬件平台,开发了Android上位机软件,最后对系统的跟随性能、施肥精度和施肥均匀性进行了试验。试验的结果表明:系统的平均响应时间为700ms,实际平均转速与给定转速的相对误差小于3%,实际转速跟随给定转速在可接受范围内波动;定速条件下的排肥量相对误差不超过4%,两侧排肥口的排肥量无显著性差异;变速条件下两次试验的相对误差分别为0.6%和0.1%,说明本系统有较高的施肥精度和较好的施肥均匀性,能够满足精准农业的作业要求,同时本研究搭建了稻田气力式变量施肥机平台,为后续的研究打下了基础。

Rice is the major food crop in South of China,and frequent topdressing is conducted in the process of rice growth.Nowadays,the frequently-used rice topdressing m achine is centrifugal disc distributor,it improves work efficiency,but is hard forcentrifugal disc distributor to ensure the precision and uniformity of fertilization.At the same time,the most current researcheson variable ratio fertilization field focus on the dry land,and there is shortage of research on variable ratio fertilization controlsystem in paddy topdressing.In order to solve the above problems,a variable ratio fertilization control system based onpneum atic fertilizer and PID algorithm was designed.In the process of design,the variable ratio fertilization controller based onSTM32F103was developed,the close-loop control of fertilization motor was realized by using increm ental PID control algorithmand the corresponding android application was developed on the hardware platform Qpad-X5of the HI-TA R G ET company.Finally,in order to test the system tracking feature,precision and uniformity of fertilization,a series of experiments were carriedout.The experim ental results indicated that the average response time of the control system was about700ms,that the relativeerror between actual average revolving speed and expected revolving speed was less than3%,that the relative error of fertilizerquality was less than4%,that the fertilizer quality of8fertilization outlets had no significant differences and that the relativeerror of twice variable speed fertilization tests was0.6%and0.1%respectively.The experim ental results proved that the designedsystem has good precision and uniformity of fertilization and that it can m eet the needs of precision agriculture.It is alsoim portant that this study laid the foundation for further research.