Development of a variable-rate seeding control system for corn planters Part I: Design and laboratory experiment

Abstract

Variable-rate seeding (VRS) has had a significant impact on agricultural production by varying the seeding rate according to field conditions, which can save seeds and increase yield and net farm returns. However, domestic VRS control systems are presently unavailable in China, and the high cost of the imported VRS control systems severely restricts their adoption by domestic farmers. In this paper, a VRS control system that offers great expandability by utilizing a controller area network (CAN) and low cost by employing off-the-shelf components was presented. The developed control system was validated by laboratory experiments that were conducted at three travel speeds (6, 8, and 10 km/h) and three GPS frequencies (1, 2, and 5 Hz) compounded with seven possible seeding rates of 64,103, 69,444, 75,758, 83,333, 92,593, 104,167, and 119,048 seeds/ha. The results demonstrate that the developed compensation algorithm of seeding lag (CASL) could decreased seeding lag distance (LD) immensely: when the system applied CASL, LD values were in range 0.27–2.82 m, and average value was 0.99 m, while LD values increased to 1.35–4.93 m with average value of 2.79 m when the system didn’t use CASL. Both travel speed and GPS frequency had a significant influence (P < 0.01) on the LD, but the variation of seeding rate had no significant influence (P > 0.05), so a smaller LD could be obtained at a lower travel speed or higher GPS frequency. The largest seeding accuracy (SA) and seeding coefficient of variation (SCV) values, which assesses the control accuracy and stability of the VRS control system for varying seeding rate, were 99.68% and 0.85%, respectively, while the smallest SA and SCV values were 98.87% and 0.16%, respectively. Using the technologies of a CAN bus and algorithm for calculating the locations of planter units, the developed VRS control system was capable of flexibly expanding planter rows and independently controlling each row’s seeding rate. Further field trials were conducted in the sequel to this study (Part II: Field performance).