| The integrated technology of water-fertilizer is one of the important means of saving water and fertilizer in modern greenhouse agriculture.At present,although the cost of simple water-fertilizer integrated equipment produced in China is low,there are problems such as the low precision of fertilizer injection and the low precision of the ratio of water and fertilizer.The precision of the large-scale water-fertilizer integrated equipment is higher than that of the simple fertilizer injection equipment,but the personnel who operate and maintain the equipment must have certain professional knowledge,in the actual promotion and application of agriculture,the equipment has exposed problems such as high cost,complicated operation,poor mobility,difficult maintenance,and so on which makes it difficult for large-scale precision fertilizer injection equipment to be widely promoted in greenhouse agriculture.The rapid development of modern intelligent control technology,mobile internet technology and so on,and the update of intelligent open source hardware,this paper comprehensively uses of these technologies to carry out research on the light and simplified water-fertilizer integrated machine control system with low-cost,high-precision,easy-to-operate and remote control.The main research contents of this article are as follows.1.Developed a light and simplified water-fertilizer integrated machine control system.According to the greenhouse environment irrigation and fertilization operation process,the overall control plan of the system is designed,the system is divided into the upper computer control system and the lower computer data acquisition system.The upper computer takes Raspberry Pi 3B as the control core,and designs the hardware control circuit and implements the software,it can precisely control the wetting,water and fertilizer ratio,fertilization,and cleaning processes of the greenhouse irrigation and fertilization process.The lower computer uses Arduino as the control core,designs the hardware control circuit and implements the software,by collecting the water speed and fertilizer speed,and uploading to the upper computer system in real time,it can provide accurate data support for the upper computer system to execute the control algorithm.The design of a remote App reduces the difficulty of farmers' control and management systems,it can record irrigation and fertilization information,and supports remote control and viewing of irrigation and fertilization information.2.Design the control algorithm of the light and simplified water-fertilizer integrated machine control system,and design experiments to verify it.Prior to system irrigation and fertilization control,precise water speed and fertilizer speed support are required.The flow control algorithm is designed and experimentally verified to obtain accurate water speed and fertilizer speed data.According to the control process of greenhouse irrigation and fertilization,the wetting time control algorithm,PWM real-time control algorithm for water and fertilizer ratio,fertilization time control algorithm and cleaning time control algorithm are designed to achieve precise control of each irrigation and fertilization link.The ratio of irrigation water to fertilizer application is 500:15,600:15 and 700:15 as an example,the designed system control algorithm has been verified by multiple experiments.The verification results show that the error between the ratio of water-fertilizer after the system control and the standard water-fertilizer ratio is less than 0.6,and the error of the system control fertilization accuracy is less than 5%.3.Using single neuron adaptive PID algorithm to control the ratio of water-fertilizer.According to the error between the real-time water-fertilizer ratio and the standard waterfertilizer ratio,the control quantity PWM is dynamically output to quickly adjust the fertilizer speed to near the expected value,and dynamically fine-tune the fertilizer speed to adapt to the change of water speed.The system test verification is carried out with the irrigation water volume and the applied fertilizer volume as 500:15,the test results show that at 8 seconds,the error between the real-time water-fertilizer ratio and the standard water-fertilizer ratio is reduced to the set error range.After that,the system continues to fine-tune the fertilizer speed according to the change of water speed,which has certain adaptability.The system mainly designs flow control algorithm,PWM real-time control algorithm and fertilization time control algorithm,and verifies the control algorithm through field tests,the test results show that the system can control the proportion of water and fertilizer in real time and accurately control the amount of fertilizer.The ratio of water to fertilizer is adjusted through a single neuron PID algorithm,which shortens the time for adjusting the ratio of water to fertilizer,and has certain adaptability to the dynamic changes of water speed.Reduce the overall cost of the system by designing the system control circuit.And design a software system to control the irrigation and fertilization process.Combine the App with Bluetooth technology to realize one-key remote control of the system within a certain range. |
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