Research On The Precision Ratio Control System For Large-flow Water-fertilizer In Tomato Farm

Currently,No.1 central document and agricultural machinery subsidy policy clearly indicate to increase capital investment for the large-flow(18 m~3/h)irrigation head system with function of integration of water and fertilize.The difficulty of large-flow head irrigation is the poor precision and stability of water-fertilizer proportioning.In addition,our current model of agronomy and water-fertilizer proportioning lacks theoretical support,and the control of precise water-fertilizer proportioning can’t realize automation and remote monitoring,which resulting in a single method of whole large-flow water-fertilizer precise proportioning system.The research content aimed at the above issues is as follows:Research on impact factor of tomato’s water-fertilizer during fruiting period.Aiming at the problem of low control precision of tradition orthogonal rotation experiments on impact factor of crops water-fertilizer proportioning and only a few results have theoretical support,taking Wada tomato No.1 as an example,designing a dynamic adjustment model of impact factor on water and fertilizer during tomato fruiting period which is the most critical to the economy,encoding the the parameter factors of the quadratic regression equation with orthogonal fitting,optimizing it through the PSO algorithm,then obtaining an economic water-fertilizer proportioning plan:EC=1.85 m S/cm,p H=5.33,FR=42 g,Q=3.8 L/h.Research on control strategy of precise water-fertilizer proportioning.Analyzing the precision and stability defects of traditional control strategy for fertilizer EC and p H,designing the large-flow water-fertilizer precise proportioning system based on genetic algorithm control,optimizing the quantitative factors of fuzzy control by genetic algorithm,then using fuzzy control to adjust PID parameter in real-time,thus achieving precise and stable control of water-fertilizer EC and p H.The results indicate that:the overshoot of fuzzy PID control optimized by genetic algorithm is 7%,which is much smaller than that of fuzzy PID and PID control strategy,the response time is 261 s and 111s shorter than PID and fuzzy PID respectively.Research on main body of control system.The control system adopts the control mode with taking PLC as the core and touch screen as the location operation,building Dc web cloud to transmit information by 4G DTU to realize two-way control,completing large-flow water-fertilizer EC and p H precise proportioning,sensor signal collection,automatic operation and remote monitoring of solenoid valves and regulating pumps,and achieving the entire process of crop growth from precise fertilization,data transmission,and timely alarm.Greenhouse field experiment on large-flow water-fertilizer precise proportioning control system in tomato farm.Conducting experimental design on the precision and uniformity of water-fertilizer proportioning,the results show that:at the flow rate of 20 m~3/h of water-fertilizer,the steady-state error between the water-fertilizer EC and p H values proportioned by the genetic algorithm controller is less than 2%,the coefficient of variation(CV)between the water-fertilizer mass fraction and the ion concentration proportioned by the experiment is less than 5%.