To improve the accuracy of discrete element simulation in the process of separating potato–soil mixtures, the contact parameters of sandy soil with 3, 6, 9, and 12% water content were calibrated in DEM simulation using EDEM software simulation. The error of the rest angle between them was used as an index, and the approach of performing only one simulation and multiple Box–Behnken response surface analyses was proposed to determine the optimal parameter combinations. Meanwhile, unconfined compression and direct shear tests were conducted to obtain the parameters of polymer bonds for soil with different water content, and a simulation was carried out using EDEM. The test results show that the significant parameters affecting the rest angle are JKR surface energy, soil interparticle recovery coefficient, and rolling friction factor. The numerical simulation of the rest angle was compared with the physical test, and the maximum relative error between them was 4.72%. The bond parameters of soil with different water content and firmness were obtained and compared with the simulation test, the maximum error was 6.53% for the direct shear test and 8.07% for the unconfined compression test, which proved that the bonding parameters are reliable and provide an effective parametric and theoretical basis for the discrete element simulation of soil particles.

The poor adsorption stability of the current air-suction sunflower seed-metering devices under high-speed operation leads to unstable seed adsorption posture, as well as increases in the multiple and miss indices. In order to improve the stability of seed adsorption, an air-suction sunflower seed-metering device based on structure-assisted stable suction posture was designed, the movement mechanism of the seed absorption process and the seed-feeding process is analyzed, following which mathematical models of the processes are established, and the key factors affecting the seeding performance were determined. Furthermore, the shape parameter equation of sunflower seeds is fitted, depending on the dimensions and shape parameters, which provides the design basis for the key components of the seed-metering device. Moreover, in order to optimize the seed-metering devices structure, taking the depth, width, and length of the seed suction grooves as experimental factors, as well as the qualified, multiple, and miss indices as evaluation indices, an orthogonal regression experiment considering three factors and three levels is carried out using the Box–Behnken experimental design. Finally, multiple regression models are established and extreme value theory is used to optimize the parameters of the influencing factors and obtain optimal parameter combinations. The optimal parameter combination is as follows: width of the suction groove, 10.5 mm; depth, 3 mm; and length, 23 mm. Results from verification experiments revealed the corresponding experimental indicators, the qualified index is 91.63%, the multiple index is 5.63%, and the miss index is 2.74%, thus meeting the requirements of effective sunflower seed sowing.

To address the problems of low pickup rates and high rates of wounds in the mechanised harvesting of potatoes under sectional harvesting conditions, a spring-finger potato picker was designed and its overall structure and working principles were described. The kinematic principle of the spring-finger was analysed based on the picking constraints, and the kinematic parameters of the picker were determined. A response surface Box–Behnken Design test design was used to carry out a quadratic orthogonal rotational test, with the speed of the spring-finger, the forward speed of the machine, and the embedded depth as test factors, and the loss rate and the wounded potato rate as evaluation indicators. The test results were optimised and analysed. When the spring-finger speed was 19.57 r/min, the forward speed was 0.61 m/s and the embedded depth was 71.31 mm, the loss rate was 1.18%, and the wounded potato rate was 5.71%. The optimised data were verified, and the results showed that the loss rate of the spring-finger potato picker was 1.48% and the wounded potato rate was 4.98%, meeting the potato picking and harvesting requirements. The research can provide a theoretical basis and design reference for the development and application of sectional potato harvesting machinery.

This paper proposes a solution to the problem of tight population in the filling area of traditional air suction seed metering devices during quinoa sowing, which leads to inaccurate adsorption. The proposed method disperses the population into a stable seed flow and absorbs the seeds in a flow posture. The flow adsorption precision seed metering device is designed and improved, and the key structure parameters are optimized based on the shape and size parameters of quinoa seeds. A four-factor and three-level response surface orthogonal test is conducted using the Box–Behnken experimental design. The number of seeds, flow angle, negative pressure at the suction hole, and advancing speed are taken as experimental factors, and the qualified index of grain number per hole, qualified index of hole distance, and coefficient of variation of hole distance are used as evaluation indices. The results are optimized using extreme value theory, and it is found that when the seed amount is 5.82 mm, the flow angle is 31.08°, the negative pressure of the air chamber is 1.7 kPa, and the advancing speed is 3.82 km·h⁻¹, and the qualified index of hole number is 94.37%, the qualified index of hole distance is 95.39%, and the coefficient of variation of hole distance is 4.51%. The results are in general agreement with the prediction through the bench validation test, which meets the requirements of quinoa seed metering devices.

To address problems encountered in current potato harvesting machines, such as potato damage, poor adaptability, and low operational efficiency, a new towed potato picking and bagging machine (4UJ-180A) equipped with a soil-digging axis, flexible conveying device, and hydraulic control system was developed. The digging mechanism of the harvester can reduce soil blockage and minimize damage to potato skins. The rubber biomimetic finger can maintain stable transportation of potatoes and minimize collisions. The hydraulic control system, the buffering components, and the bagging device work together to flexibly and continuously collect potatoes, reducing skin damage during the harvesting process. Based on the structure of the whole machine, the harvesting process, and the working principle, the soil picking, lifting buffer, and potato collection process were analyzed. Theoretical calculations were used to determine the structure and operational parameters of the potato picking, lifting buffering, and bagging segments. An experiment utilizing the orthogonal method was conducted. The experiment consisted of three factors and three levels, with the test indicators being the potato skin damage rate, potato injury rate, loss rate, and impurity rate. The factors considered in the experiment were the forward speed, conveyor speed, and soil-digging shaft speed. Field experiments demonstrate that at a forward speed of 1 m/s, soil digging shaft speed of 35 rpm, and conveyor speed of 28 rpm, the rate of potato skin damage is 2.8%, the potato injury rate is 1.3%, the loss rate is 0.4%, and the impurity rate is 0.7%. These experiments verify that all indicators adhere to national industry standards, providing a valuable reference for equipment research, development, optimization, and improvement.