*3.1. Test Materials and Platforms*

The variable application test of liquid manure was conducted in November 2021 and September 2022 at the test site of Tai'an Yimeite Co. Ltd. The test platform included a self-priming jet pump, monitoring and control via computer, electric proportional valve, flowmeter, distributor, and sprinkler pipe (Figure 16). The max lift of the self-priming jet pump was 15 m, the maximum absorption was 10 m, and the maximum flow was 81 L/min. The controller used the Siemens PLCS7–200 series, and the control software used the force control configuration software. The maximum diameter of the solenoid valve core was 18 mm. The maximum flow under 0.15 MPa pressure was 100 L/min.

**Figure 16.** Test platform. 1: pump; 2: monitoring and control via computer; 3: electric proportional valve; 4: flow meter; 5: distributor; 6: sprinkler pipe.

The control object of the test was a proportional solenoid valve. The experiment material was clean water without suspended solids. The measurement and verification of the control accuracy of the flow rate of liquid manure distribution were carried out for classical PID control, fuzzy PID control, BPNN–PID control, and GA–BPNN–PID control.

The solenoid valve and control system of the experiment platform were powered by an onboard DC. The controller and actuator converted 48 V DC to 24 V DC by switching the power supply before sending them to the dominant system. The experiment platform was 1.8 m tall and 1.2 m broad.
