Optimizing the working performance of the cutting device for harvesting Chinese little greens is crucial to reducing energy consumption in cutting and improving cutting quality. To explore the mechanical characteristics of leafy vegetables in cutting, the dynamic process of cutting Chinese little greens with a cutter was simulated numerically by using the finite element method based on theoretical analysis. In the numerical simulation, the response-surface methodology (RSM) and central composite rotatable design (CCD) were used to describe the influence rule of sliding–cutting angle (X₁), oblique angle (X₂), and the average cutting speed (X₃) on cutting stress. Then, the stress distribution pattern produced by the cutting blade and the stalks were evaluated by using different working parameters. Subsequently, taking the minimum cutting stress as the target value, the best combination of cutter structure and working parameters were obtained: the sliding–cutting angle was 29°, the oblique angle was 38°, and the average cutting speed was 500 mm/s. At the condition of optimal parameter combinations, the ultimate cutting stress of the upper cutting blade was 0.95 Mpa and that of the bottom cutting blade was 0.77 Mpa. A cutting test was carried out by using a bench test of the cutting performance, and the mechanical properties of cutting at different cutting speeds were studied. Test results showed that at the optimal cutting speed of 500 mm/s, the cutting stress on the cutter was relatively small and the cutting effect reached the best value. The finite element simulation of cutting the little greens reduced the test cost and provided a reference for the development of a cutting device with low power consumption.

The cutting device in the seedling grafting process was studied, which provided a reference for optimizing the structural parameters and working parameters of important shearing components in the seedling grafting line, thereby improving the performance of the cutting device. The dynamic cutting process of the cutting device was numerically simulated. The effects of four factors, the average cutting speed (X₁), the sliding angle (X₂), the cutting edge angle (X₃), and the cutter clearance (X₄) on the cutting force, were studied. The optimal combination of structural parameters and working parameters of the cutting device was determined. The simulation results showed that the sliding angle (X₂) and the cutting edge angle (X₃) affect the ultimate cutting stress. The average cutting speed (X₁) and the cutter clearance (X₄) affect the ultimate cutting force. When X₁, X₂, X_3, and X₄ are 579 mm/s, 39°, 25°, and 1.4 mm, respectively, it is the better combination parameter, and the ultimate cutting equivalent stress of the cutting device is 0.32 Mpa. A high-speed cutting device for grafted seedlings was built, and the cutting experiment was carried out. The experiment results showed that the simulated values fit well with the experimental data. Under the optimal combination of cutting parameters, the cutting stress of the cutting device was smaller. The finite element simulation of the seedling grafting cutting device reduces the experiment cost and provides a reference for developing the seedling grafting line.

In order to obtain desirable crop yields, grain seeds need to be sown at the optimal seed amount per hectare with uniform distribution in the field. In previous grain sowing processes, the seeding rates are controlled by the rotational speed of the flute roller which significantly effects the uniform distribution of the seeds due to disturbances, such as the reduction of the seeds’ mass in the hopper and the change of working length of the flute roller. In order to overcome the above problem, we developed an adaptive roller speed control system based on the seed flow rate sensor. The developed system can monitor and feedback actual seeding rates. In addition, based on the monitoring value of the real-time seeding rates, an adaptive roller speed control method (ARSCM), which contains an algorithm for calculating the seeding rate with a compensation, was proposed. Besides, the seeding performance of the ARSCM and that of the conventional roller speed control method (CRSCM) were compared. The results of constant-velocity experiments demonstrated that the accuracy (SA) and the coefficient of variation (SCV) of the seeding rates controlled by the ARSCM were 94.12% and 6.77%, respectively. As for the CRSCM, the SA and SCV were 89.00% and 8.95%, respectively. Under variable-velocity conditions, the SA and SCV of the proposed system were 91.58% and 11.08%, respectively, while those of the CRSCM were 88.48% and 13.08%, respectively. Based on the above results, this study concluded that the ARSCM is able to replace the CRSCM in practical sowing processes for the optimal and uniform seed distribution in the field.