High Precision Control Method of Liquid Fertilizer Flow Based on Sliding Mode Technology

To improve the utilization rate of liquid fertilizer, a high-precision control method of liquid fertilizer flow based on sliding mode technology was proposed. Firstly, the working process of liquid fertilizer flow control by electric control valve was analyzed, and the liquid fertilizer flow control model was established. Then, the integral sliding mode surface was designed for the valve opening, motor speed and motor angular acceleration in the electric control valve, and the sliding mode control law was proposed. Finally, the stability of liquid fertilizer flow control system was analyzed. The simulation results show that the designed sliding mode control method has better rapidity and accuracy, the response time is less than 0.6 s, the maximum error of valve opening is only 0.01 cm, the maximum error of liquid fertilizer flow is only 1 ml, and the maximum tracking error of liquid fertilizer flow is only 0.1 ml/s. In the measurement of tomato liquid fertilizer, the maximum flow error is only 0.03 ml, and the control precision is high, which can realize the precision fertilization of modern agriculture.