In order to improve the adaptability of the seedling feeding devices to different plug trays for various seedlings, a multi-adaptive plug seedling feeding device for automatic field transplantation was developed. Its efficiency and adaptability have been improved using a seedling delivery device equipped with a row of end-effectors, which were provided with continuous plug seedlings by a compact seedling tray conveyor carrying out a reciprocating action. Each operation for the seedling feeding device could work automatically through a control system. Three categories of plug seedlings, cucumber, pepper and tomato seedlings, were tested. The results of the performance test for the prototype demonstrated that the best performance emerged in the cucumber seedlings in 50-cell trays with the highest success rate of 88% at the feeding frequency of 6 groups/min. The lowest success rate was 73.33% for the tomato seedlings in 105-cell trays at the feeding frequency of 12 groups/min. It can be concluded that the automated feeding device developed in this study could be used for various plug seedlings as a result of its strong adaptability. Keywords: plug seedling, automated feeding device, vegetable transplanting, control system DOI: 10.25165/j.ijabe.20211402.6003 Citation: Shao Y Y, Han X, Xuan G T, Liu Y, Gao C, Wang G P, et al. Development of a multi-adaptive feeding device for automated plug seedling transplanter. Int J Agric & Biol Eng, 2021; 14(2): 91–96.

In this study, a 4UM-120D electric leafy vegetable harvester was employed as the research object. An automatic control system was created to maintain the cutter’s height above the ground within ±2% of the desired value. The intention was to reduce the operators’ work intensity while improving the leafy vegetable harvester’s working quality. The automatic control system for the cutter height from the ground was explained, along with its structure and operating philosophy. MATLAB was used to establish the two-phase hybrid stepper motor’s mathematical electrical equation and mechanical equation models. An analysis was carried out on the fundamentals and differences between position PID and incremental PID control algorithms. Utilizing incremental PID in combination, the control strategy for the harvester cutter height from the ground was built, and an automatic control system was produced under the corresponding control strategy. The stability, accuracy, and rapidity of the automatic control system of the cutter height from the ground under the incremental PID control strategy were analyzed by simulating different actual working conditions with MATLAB/Simulink and taking the steady-state transition time as the evaluation index. The test results show that when the deviation between the current value and the set value was greater than 2%—that is, when the harvester was in the condition of suddenly crossing the ditch or suddenly climbing the slope—the automatic control system based on the incremental PID control strategy had a good dynamic response performance and stability. This resulted in the automatic control function of the harvester cutter height off the ground being achieved. When the rotation angle PID control algorithm’s proportional coefficient is Kp = 4.665, the rotation speed PID control algorithm’s proportional coefficient is Kp = 5.65 and its integral coefficient is Ki = 3.86, and the current PID control algorithm’s proportional coefficient is Kp = 0.5455 and its integral coefficient is Ki = 30.4578. The harvester abruptly crossed a ditch while operating steadily, and the automatic control system’s steady-state transition time for the height of the cutter off the ground was 1.0811 s. The harvester abruptly climbed a slope while operating steadily, and the automatic control system’s steady-state transition time for the height of the cutter off the ground was 1.1185 s. Data from the field tests revealed a degree of reliability in the simulation test results. The study offered a strategy for raising the harvester quality for leafy vegetables while lowering the operator workload.

At present, there are no harvesters specifically adapted to process peanuts after cutting stalks. In particular, methods for harvesting peanuts after cutting stalks have not been reported thus far. Therefore, to utilize peanut stalks as feed when harvesting plastic-film-grown peanuts, and to improve industry benefits, a three-stage harvesting method is proposed herein. In view of the three-stage harvesting method, the peanut stalks are cut before digging, with the remaining peanut plants being shorter, thereby increasing the peanut pod-stalk ratio. To investigate the adaptabilities of existing harvesters in harvesting peanuts after cutting stalks, three types of peanut harvesters—the self-propelled pick-up combine harvester, trailed pick-up combine harvester, and peanut picker were used to conduct a comparative test on harvesting intact peanut plants and plants after cutting stalks. The loss, breakage and impurity rates were used as evaluation indicators. The loss rates of these three harvesters were 14.64%, 16.44% and 1.33%; the breakage rates were 21.28%, 21.92% and 20.00%, and impurity rates were 4.60%, 8.76% and 9.06%. Analysis of variance showed that cutting stalks had a significant impact on the work qualities of the three harvesters (p < 0.05). With regard to the loss rate, results revealed that: the two peanut combine harvesters could not be adapted to harvest peanut plants after cutting stalks. The three harvesters had good adaptability to harvest peanut plants after cutting stalks, considering the breakage rate; however, based on the impurity rate, the three harvesters could not be adapted to harvest peanut plants after cutting stalks. The losses of the two combine harvesters consisted mainly of dropped and missed picking, with the sum of the losses accounting for 99.87% and 97.99% of the total losses of the two harvesters, respectively; this suggests that the drum pickup of the combine harvesters could not adapt to harvesting the peanut after cutting stalks. The breakage rates of the three harvesters were considerably reduced, suggesting that the pod picking devices of the three harvesters were suitable for harvesting the peanut after cutting stalks; the impurity rates of the three harvesters were considerably increased, indicating that the pod picking and cleaning devices of the three harvesters were not suitable for harvesting peanut after cutting stalks. To improve the adaptabilities of the harvesters, it is suggested that the speed of pickup elastic tooth, lateral spacing between adjacent elastic teeth, concave screen hole size of pod picking device, the structure and motion parameters of cleaning device should be optimized. The results of this study provide a reference for the development and improvement of peanut harvesters suitable for harvesting peanuts after the cutting of stalks. Keywords: agricultural machinery, peanut, peanut harvesting after cutting stalks, peanut combine harvester, peanut picker, adaptability research DOI: 10.25165/j.ijabe.20221502.6515 Citation: Chen Y Q, Wang G P, Wang J T, Zhang P, Wang B, Hu Z C. Adaptabilities of different harvesters to peanut plants after cutting stalks. Int J Agric & Biol Eng, 2022; 15(2): 93–101.

Research and optimization of the hand-over lifting mechanism of a sweet potato combine harvester based on EDEM

The study developed a PID-based automatic control system for travel speed based on the analysis of the entire machine structure of the 4UM-120D electric leafy vegetable harvester to enhance the operation quality of the harvester and lessen the workload of operators. Taking the system adjustment time during the process of starting and maintaining the travel speed of the harvester within ±2% of the set value as the main evaluation index, the Box–Behnken test method was applied based on the single-factor test, and the proportional coefficient Kp, the integral coefficient Ki and the initial value U of the travel motor drive voltage of the PID control algorithm were used as the test factors, and the PID-based 4UM-120D electric leafy vegetable harvester travel speed automatic control system operating parameters based on PID was studied in a three-factor, three-level experiment, and a multiple regression model of evaluation indexes on each factor was established to analyze the influence of each factor on system rapidity and to obtain the optimal operating parameters. The test findings demonstrated that the beginning value of the driving voltage of the travel motor U, the integration factor Ki, and the proportionality factor Kp had the largest to smallest influences on the system regulation time. When the initial value of the driving voltage of the travel motor was 1.81 V, the integration factor was 0.020, the proportionality factor was 0.127, the system regulation time was 2.14 s, and the relative error was 1.8% compared with the optimized value. The results of the study could provide a way to improve the operation quality of leafy vegetable harvesters and reduce the work intensity of operators.

This paper used the 4UM-120D electric leafy vegetable harvester as the research object and designed a travel speed automatic control system to maintain the travel speed within a set value of ±2% in order to improve the efficiency and quality of leafy vegetable harvester operations and decrease the work intensity of the operator. The harvester’s travel speed was automatically controlled by using the PID, adaptive fuzzy PID, and sliding mode control techniques after the mechanical and electrical equations for the travel drive motor (a DC brushless motor) were established in MATLAB. By simulating various working situations, the stability, accuracy, and speed of the automatic control system were compared and analyzed using the adjustment time, overshoot, steady-state transition time, and maximum deviation from the set speed as evaluation indicators. The test results revealed that when the current value of the leafy vegetable harvester travel speed deviated from the set value by more than 2%, the dynamic response performance and stability of the DC brushless motor travel drive system based on the sliding mode control strategy was significantly better than that of the PID and adaptive fuzzy PID control strategies, and its anti-disturbance was stronger, achieving the function of automatic control of the harvester travel speed. When the travel motor started with a constant load and the sliding mode control strategy’s parameters were the gain factors A = 1/70, c = 100, ε = 100, and k = 100, the travel drive system regulation time was 1.5 s, and the overshoot was 10%. When the harvester was operating smoothly and had leafy vegetable collection baskets loaded and unloaded, the steady-state transition time was 0.3 s. According to the actual engineering application experience, the specific technical state of the control strategy of the agricultural machinery travel speed automatic control system was: regulation time 2.5~3 s; overshoot amount 20~25%; and steady-state transition time 1.0~1.5 s, so the travel speed automatic control system of the electric leafy vegetable harvester in sliding mode was in line with the technical state requirements. The results of the field trials demonstrated the accuracy of the simulation test results. This study offered a method to lessen the work intensity of operators and increase the operating efficiency and quality of a leafy vegetable harvester.