To address the errors associated with the application of existing Discrete Element Method simulation parameters in roller-type precision seeders, this study focused on calibrating the key contact parameters of the ‘Xinhe No. 1’ coated confectionary sunflower seeds, so as to provide a reliable simulation foundation for the optimization of the seeders. Through dynamic stacking angle experiments and comparative trials involving confectionary sunflowers (including Xinhe No. 1) and oil sunflowers with significantly different physical properties, the optimal working conditions for the rotating drum were determined as a rotation speed of 10 r/min, 304 Stainless Steel as the inner wall material, and a filling ratio of 30%. The study also clarified the variation patterns of the dynamic stacking angle. Physical experiments were conducted to measure the static friction coefficients, restitution coefficients, and inter-seed restitution coefficients between Xinhe No. 1 seeds and three materials: 304 Stainless Steel, Q235 Steel, and ABS Plastic. The physical dynamic stacking angle was obtained via a rotating drum experiment. A single-factor experiment was used to determine the range of simulation parameters, and a second-order orthogonal experiment was conducted using Design-Expert software to optimize contact parameters with the physical dynamic stacking angle as the target. The parameters were subsequently validated using the Discrete Element Method (DEM) simulation software EDEM 2022.3, hereinafter abbreviated as EDEM simulations. Finally, rolling friction coefficients between seeds and Q235 Steel and ABS Plastic were obtained through both simulation and physical experiments using alternative contact materials. The results showed that the static friction coefficients between Xinhe No. 1 and 304 Stainless Steel, Q235 Steel, and ABS Plastic were 0.32, 0.36, and 0.25, respectively; the restitution coefficients were 0.42, 0.39, and 0.32; and the rolling friction coefficients were 0.012, 0.011, and 0.010. The measured values of the inter-seed static friction coefficient, restitution coefficient, and rolling friction coefficient were 0.31, 0.43, and 0.010, respectively. The relative error between simulated and physical stacking angles was <1.5%. Calibrated DEM parameters for Xinhe No. 1 coated sunflower seeds provide a theoretical basis for optimizing the design of sunflower precision seeders.

The congenital yield reduction caused by miss-seeding in spoon-type seed-metering device of small and medium-sized potato planter is huge. Based on the physical mechanism of different measured capacitance values between two fixed capacitor plates with different media, a miss-seeding detection scheme based on a spatial capacitance sensor is proposed first. A simple and efficient spatial capacitance sensor that can obtain as large capacitance measurement value as possible is designed, and a dual CPU coordinated seed-monitoring and compensation control system architecture is adopted. AD7745 is selected for the capacitance measure of the spatial capacitance sensor, and the code of grating encoder is also recorded at the same time. Thereby, when each potato spoon passing through the space surrounded by the capacitor plates, the maximum net capacitance fluctuation and its corresponding position can be acquired. A suitable threshold can distinguish between normal-seeding and miss-seeding effectively. Moreover, it should be emphasized that, this monitoring system only requires one monitoring point. Then, based on obtained information, an improved miss-seeding catching-up compensation plan is put forward. By utilizing the powerful memory capability of the CPU, this system does not need to complete compensation immediately after the miss-seeding identification. Instead, the miss-seeding information and the location of the accident can be just marked in advance, and only when the opportunity arrives, can the miss-seeding catching-up compensation be truly executed. In this way, the position of the seed-monitoring points can be free from restriction, and the control strategy can therefore be significantly simplified. The soil tank test data showed that, the identification accuracy of the miss-seeding detection system was not less than 94%. When the seed-metering chain speeds are 0.2, 0.3, and 0.4 m/s, the average success rates of the miss-seeding compensation system are 94.32%, 83.65%, and 75.00%, respectively. The final miss-seeding rate can be below 3%, and the average deviation compensation rate was not higher than 30%, the miss-seeding was suppressed significantly. This system is a beneficial try in the non-photoelectric detection field and low complexity miss-seeding compensation for potato seeding.