The control strategy and verification for precise water-fertilizer irrigation system

In terms of the precise control problems of water and fertilizer density during agricultural fertilization and irrigation periods, designing a control technology that based on PID control technology, the application of conductivity value and pH value to develop precise water and fertilizer irrigation control system. The thesis also performed theoretical analysis and experiment of digital PID control of EC value, the results indicated that the PID control system has the advantages of high control precision, but the control performance is degradation when the fertilizer density changes greatly. The intelligent PID controller with EC value was designed by using open-loop step response, PID control technology and inaccurate-control technology. The test results show that it has PID parameter self-controlling ability, good control performance, the stable time within 3 minutes, precision degree is within +/- 0.15mS/cm, overshoot less than 15% The improved intelligent PID controller control the pH value, through using open-loop step control and PID control, the test shows that the stability time within 3 minutes, the accuracy is Within +/- 0.15pH, overshoot less than 15%.