3.3.2. Variable Control Test

In the variable control test, a data acquisition card was used to collect the angular velocity sensor data. The square wave signal generated by the angular velocity sensor was used to calculate the vehicle speed. The gathered square wave signal was installed and stored through the programmable signal generator. In this test, a programmable signal generator was used to simulate the electrical signal when speed changed, and the classical PID, fuzzy PID control, BPNN–PID control, and GA–BPNN–PID control were used for variable control of liquid manure flow.

In this test, the discharge of liquid manure was determined using a flowmeter. Test data were noted after system stability. Test results for the liquid manure spreading control under the condition of vehicle speed change are shown in Figures 17–20. During the spreading control system, the flow regulation's average response time with the classical PID control was 5.02 s, the fuzzy PID control was 4.19 s, the BPNN-PID control was 3.97 s, and the GA–BPNN–PID control was 2.85 s. These results indicate that the actual response time of GA–BPNN–PID control was 2.17 s less than that of PID control, 1.34 s less than that

of fuzzy PID control, and 1.12 s less than that of BPNN–PID control. The GA–BPNN–PID had the fastest response speed and better flow control stability.

**Figure 17.** Test results of liquid manure flow by PID control.

**Figure 18.** Test results of liquid manure flow by fuzzy PID control.

**Figure 19.** Test results of liquid manure flow by BPNN–PID control.

**Figure 20.** Test results of liquid manure flow by GA–BPNN–PID control.
