四要素变量施肥机肥箱施肥量控制算法设计与试验

针对黑龙江农垦地区垄作玉米施肥过程中遇到的肥料分层问题，设计了一种四要素变量施肥控制系统。系统采用电液比例控制技术，主要由液晶显示终端、变量施肥控制器、4路液压马达和编码器、4路排肥机构（排肥轴和外槽轮）和GNSS模块组成。为了实现氮肥、磷肥、钾肥和微肥的一次性及时、准确施用，提出了一种基于复合交叉原则的各路施肥量确定策略，基于PID技术设计了液压马达控制算法。根据用户在变量施肥控制软件中设置的目标施肥量，系统自动确定各肥箱精确施肥量，基于PID液压马达控制算法，实时计算4路液压马达的目标转速，同步向控制器发送4路转速指令，一次性完成氮肥、磷肥、钾肥和微肥4种肥料的同步变量施用。为了验证各路施肥量控制算法的效果，分别进行了PID算法响应时间和精度试验、变量施肥系统单质肥排肥性能验证试验和作业条件下各肥箱施肥量控制算法验证试验。试验结果表明，基于PID技术的排肥轴转速控制算法响应时间不大于0.5s；变量施肥系统单质肥排肥性能误差绝对值不大于3%；作业条件下各路施肥量控制算法显著减少了氮素的施用量，实现了氮肥、磷肥、钾肥的精确投入。四要素变量施肥机各路施肥量控制算法完全满足了垦区玉米施肥精确、均匀施用的要求。

Design and Experiment of Fertilizer Amount Control Algorithm in Four Factors Variable Rate Fertilization System

In view of the Heilongjiang agricultural reclamation region fertilizer layered problems, a variable rate fertilization control system was developed. It consisted of the vehicle intelligent terminal, the variable rate fertilization controller, four channel speed sensor, four channel hydraulic motor, four channel fertilizer components, GNSS receiver and work status sensor. In order to apply the fertilizer of nitrogen, phosphorus, potassium and micronutrient accurately, a new fertilizer amount strategy with the compound crossover principle was proposed. And then with the PID technology, hydraulic motor control algorithm was designed. When the system started to work, according to the set target values of N, P and K, the actual value of N, P and K would be determined automatically with the corresponding strategy. Subsequently, the hydraulic motor speed would be calculated. Nitrogen fertilizer, phosphate fertilizer, potassium fertilizer and micronutrient fertilizer could be fertilized at one time. In order to verify the effect of the fertilizer amount control algorithm, three experiments were carried out. The results showed that the distributing shaft based on PID control algorithm of response time was less than 0.5s, the system of variable rate fertilization elemental performance error absolute value was no more than 3%. Under the operating condition, it could reduce the use of nitrogen fertilizer obviously and more accurate for N, P and K than that without the algorithm. The control algorithm of the fertilizer amount of the four-factor variable fertilizer application machine completely satisfied the requirements of precise and uniform application of maize fertilization in reclamation area.