*2.7. Simulation Analysis of Spraying Control System*

2.7.1. Modeling and Simulation of PID Control System

To achieve a control system model for liquid manure precise spraying, the classic PID control simulation variable spraying control system model of liquid manure was built using the Simulink simulation module in MATLAB software. The amplitude of import step signal was disabled by two. PID controller arguments were adjusted. The waveform of the system output was analyzed.

In the PID control simulation model, when t = 0, the import amplitude step signal was 2. Simulation time was disabled at 20 s. The KP, KI, and KD of PID control were set. Finally, the oscilloscope output a waveform. The simulated waveforms are displayed in Figure 10.

**Figure 10.** Simulation waveform of PID control model.

As shown in Figure 9, the model response time was 8.6 s, the overshoot was 0.019, and there was some oscillation before the system operation reached stability. Finally, KP = 42, KI = 0.51, and KD = 0.01 were selected according to the empirical trial method.
