2.3.1. Bench Test

In this study, the cotton seeds of Xinluzao 78 were used as the experimental material. Its thousand-grain mass was 84.40 g, and the moisture content was 4.45%. The average values of the maximum length, maximum width, and maximum thickness of the cotton seeds were 8.52, 4.50, and 4.48 mm, respectively. The standard deviations were 0.43, 0.32, and 0.41, respectively. The test equipment included a double-silo turntable test bench for the cotton vertical disc seed metering device, a stepper motor controller, and a cotton sowing quality monitoring system. To evaluate the accuracy of sowing quantity and missed sowing monitoring of the cotton sowing quality monitoring system, a bench test of the sowing quality monitoring system was designed. The test bench is shown in Figure 6.

**Figure 6.** Test bench of the monitoring system.

The purpose of the experiment was to evaluate the accuracy and stability of the sowing quality monitoring system of cotton precision planters. In the experiment, a double-silo turntable type vertical disc hole seeding and metering device was used. It set different rotational speeds for seed metering monitoring tests. The missed-seeding monitoring module was installed on the seed spacer. An inoculation bag was used to collect cotton seeds that had passed the missed-seeding monitoring module. By changing the speed of the seeding disc, the amount of seeding per unit time could be adjusted. In order to ensure that the seed meter works within the normal range of seed metering frequency, the rotation speeds were set to 20, 25, and 30 r/min [32]. It recorded the seed number displayed by the industrial computer. The actual number of cotton seeds in the inoculation bag was obtained by a manual method to calculate the actual sowing rate. It was compared with the monitoring value of the monitoring system to evaluate the accuracy of the system's sowing detection. The test was repeated 3 times, and the results were averaged to avoid errors.
