Design and experiment of the wheat seed flow multi-channel parallel detection device with thin-surface light refraction

Abstract: A seed metering device is closely related to the sowing quantity and crop yield in the planting process. Various detection methods have been used to improve the seeding performance for corn, and soybean precision seeding in recent years, such as photoelectric sensor detection, high-speed photography, and capacitance sensing. However, it is difficult to accurately count the high-frequency seed flow in the process of high-speed wheat sowing. In this study, a set of multi-channel parallel detection device was designed for the wheat seed flow with thin-surface light refraction. A "LED lamp beads + narrow slots" method was also proposed to generate the thin-surface light layer, in order to combine the convex lens refraction for the large effective detection area. According to the physical characteristics of wheat seeds, the seed stream shunt structure and the thin-surface LED narrow slot size were designed to determine the convex lens focal length and the key parameters of the sensing components. The multi-channel parallel detection and sensing were utilized to develop a multi-channel signal synchronous acquisition system for the multi-channel parallel detection device of the wheat seed flow with thin-surface light refraction. The seeding accuracy rate and frequency test was conducted to improve the detection accuracy. Among them, the error rule of the detection device was analyzed to construct the accuracy compensation model. The bench test showed that the normal seeding frequency range was 52.10~321.55Hz in the field, and the detection accuracy was not less than 96.68%, when the rotation speed of the seed metering device was 80~180r/min. The comparison test showed that high reliability was achieved with a detection accuracy of not less than 96.64%, when the seeding frequency was not more than 32.75Hz. The detection accuracy rate of the single-channel detection device decreased significantly in the frequency range of 49.40~320.75Hz during seed metering in the field, with the increase of seeding frequency. There was a stable detection accuracy rate of the multi-channel parallel detection device. Specifically, the minimum detection accuracy rates were 26.67%, and 96.53%, respectively, for single and multi-channel parallel detection devices. It infers that the multi-channel parallel detection improved the detection accuracy rate of wheat seeds after shunting. The field sowing test showed that the normal seeding frequency in the field was 67.65~323.95Hz at the operating speed of 2~9km/h, and the detection accuracy was higher than 95.28% in the detection device. Consequently, the detection device can be expected to detect the seeding frequency of the seeding device, the seeding amount of each channel, and the total seeding amount in real time. There was no influence of mechanical vibration, strong light, and soil dust on the detection device in the normal field wheat sowing. The detection device can provide effective support to accurately detect the high-frequency seed flow for the missed seeding detection and reseeding in high-speed wheat sowing.