Machinery Systems and Biological Systems Engineering in Precision Agriculture

In order to explore the influence of soil force on rotary soil-engaging components during their operation, a kinetic parameter measurement system of rotary soil-engaging components was developed via the sensor strain measurement technique. By taking a single-sided compacting ridge device as an example, the kinetic experiment was carried out on the operation parameters of the compacting device and obtained the variation law of the force of the soil on the pinnae. ADAMS software was used to simulate the operation of the compacting device under different experimental factors (soil moisture content, forward speed of the ridge device, and the rotation speed of the compacting device), and the test data were obtained; the experiment was carried out with the forward speed of the soil tanker and the rotation speed of the compacting device as the experimental factors, and the average of the force of soil on the pinnae and the firmness value of the ridge were the experimental indicators. The results showed that under a moisture content of 27%, the forward speed of the device was 0.8 km∙h⁻¹, the maximum firmness of the ridge was 1233.21 kPa, the minimum firmness of the ridge was 953.85 kPa, and the coefficient of variation of the stability of the firmness value of the ridge was 8.04; the force of the pinnae on the soil increased with an increase in the forward speed of the soil tanker, and the variation range of the force was 2838.1–5695.2 N. It was verified that the design of this operation parameter measurement system for rotary soil-engaging components meets the practical requirements and also provides an important reference for the measurement of the relevant parameters of similar rotary soil-engaging components. Full article

The agronomic technology of whole plastic-film mulching on double ridges has been widely promoted in the arid region of northwest China, which has caused serious residual film pollution in the field. Mechanized residual plastic-film collecting is the main way, but this way of residual plastic-film collecting is more complicated. To prove the effect of typical film-lifting parts on residual plastic-film collecting performance by a numerical simulation method, further evaluate and select the working parts suitable for residual plastic-film collecting and improve the collecting efficiency, virtual whole plastic-film mulching on double ridges needs to be established. In this study, the film-lifting parts and the double ridge with flexible, deformable, mulching, film interaction model was developed using the discrete element method (DEM). The interaction model was used to simulate the operation process of a typical third-order shovel, hug plate and elastic teeth film-lifting parts. Furthermore, the operation resistance, seed bed disturbance and collecting residual film form under different working conditions were analyzed. The simulation results show that: the disturbance of the ridge from strong to weak is the third-order shovel, elastic teeth and hug plate film-lifting parts; the crushing of the ridge soil from strong to weak is the elastic teeth, the hug plate and the third-order shovel film-lifting parts; the collecting film from strong to weak is the hug plate, elastic teeth and the third-order shovel film-lifting parts; the median value of the horizontal force fluctuation range of the ridge soil on the film-lifting parts is increased, and the increase trend is from large to small in the third-order shovel, elastic teeth and hug plate film-lifting parts (the third-order shovel is 5250 N, 6250 N and 7750 N; the hug plate is 3250 N, 3500 N and 4000 N; and the elastic teeth are 4150 N, 4550 N and 5450 N). The comparative analysis results show that the hug plate film-lifting parts are more suitable for the residual-film collecting of whole plastic-film mulching on double ridges. Field trials were carried out to verify the operational effectiveness of the hug plate film-lifting parts. The results show that the morphological changes of the recovered residual film and the simulated mulching film during the operation of the hug plate-type residual film machine, and the distribution of the surface properties of the ridge after the residual-film collecting are basically consistent with the simulation results, and the film pick-up rate of hug plate film-lifting parts reaches 95.20%, and the established discrete element interaction model is reliable. The research results can provide reference for the research and development of full film duopoly furrow-mechanized residual film-collecting agricultural equipment in the arid region of northwest China. Full article

The labor-efficient automation of grafting has been recognized as a key factor in the wider adoption of grafting. In growing cucurbits, the root pruned one-cotyledon grafting method is the most commonly used method with grafting machines. The cutting angle, which affects the matching of the rootstock and scion, is key to the survival of the graft seedling. In the production of cucurbit graft seedlings, the cutting parameters are established based on experience, leading to low grafting success. To determine accurate cutting parameters, the watermelon cv. ‘Zaojia84-24′ was used as the scion and the pumpkin cv. ‘Zhenzhuang’ was used as rootstock, and two one-way experiments investigating the cutting angle of the watermelon scion and the rootstock as factors were conducted. The cutting angle of the rootstock and scion had no significant effect on the xylem reconnection rate or the grafting survival rate. A larger cutting angle for the rootstock and scion led to a delay in the reconnection of the phloem. Different cutting angles for the scion significantly affected the growth of the scion after grafting. Compared with a scion graft cutting angle of 10° (SL), graft cutting angles of 14° (SM) and 20° (SS) led to significantly greater scion dry weights, with increases of 16.00% and 18.61%, respectively. Different cutting angles of the rootstock significantly affected the growth of roots after grafting. Compared with a rootstock graft cutting angle of 10° (RL), graft cutting angles of 17° (RM) and 27° (RS) led to significantly greater root dry weights, with increases of 29.33% and 22.54%, respectively. The results of this study can provide a reference for the design of cutting mechanisms for cucurbit grafting robots, improving the cutting precision of grafting robots. Full article

Potato stem removal is one of the critical technical problems of potato mechanized harvesting; it directly affects the quality of potato harvesting and potato storage. There have been several studies on potato stem removal mechanisms. In practice, however, it was found that the potato stem removal rate was greatly influenced by the posture of the stem before it entered the removal mechanism. In this study, we designed a potato stem posture adjustment mechanism consisting of elastic curtains. A test rig was built to investigate the effect of curtain height, curtain width, and curtain suspension height on potato passage rate and potato stem removal rate. The Box–Behnken design (BBD), combined with the response surface method, was used to conduct the test. The optimal construction and installation parameters for each elastic curtain were determined as 278.93 mm for the curtain height, 20 mm for the curtain width, and 260 mm for the curtain suspension height. The predicted values of potato passage rate and potato stem removal rate under the optimal parameters were 92.36% and 82.83%, which were consistent with the validation test results. Based on the optimization results, a rigid-flexible coupled simulation model for a potato stem transported-posture adjustment process based on Abaqus and Adams was constructed. The maximum impact of the elastic curtain of the stem posture adjustment mechanism on the potato stem was 15.91 N and caused the stem to spring back. The projection angle β′ of the stem posture angle in the xoz plane before posture adjustment was 19.07°, and the β′ of the stem after posture adjustment was 87.18°. At this time, the stem was basically parallel to the rod of the separating sieve and had a high probability of falling from the gap of the bar to complete the removal of the stem. Overall, the stem transport position adjustment mechanism effectively adjusted the stem transported posture and improved the stem removal rate in potato mechanical harvesting. Full article

Automatic grafting and cutting machines can be employed to satisfy the increasing demand for seedlings without soil-borne diseases in a short period. The main approach used to feed seedlings for automatic grafting and cutting machines is artificial, which limits the improvement of grafting and cutting machine productivity. The separation system with a subdivision air stream can stably feed seedlings for cutting and grafting machines; however, the separation efficiency is low when a few seedlings are in the separator. To solve this problem, a feedback monitoring device with a photosensitive sensor as the sensing element and feedback functions on the status of seedlings in the separator was developed. Through experiments using a photosensitive sensor to monitor the separation process of tomato seedlings, the results showed that the effect on the effective seedling blowing rate varied from large to small depending on the seedling size, light intensity, and sensor diameter. The results of separation experiment showed that the productivity of the entire system was 8784 plants/h, which satisfies the productivity needs of the grafting and cutting machine. Compared with the separation device without feedback monitoring, the productivity increased by 39%, the damage rate decreased by 4%, and the number of subdivided air stream operations was reduced by 47%. Full article

In order to improve the operational performance of the self-developed 4HLB-4 half-feed four-row peanut combine harvester, single-factor and multifactor field tests were conducted on key operational parameters affecting the quality of harvesting. The response surface methodology was used to study the effects of the forward speed, clamping height, peanut picking roller rotational speed, and cleaning sieve vibrational frequency on the loss rate and impurity rate. A response surface regression model of the loss rate and impurity rate was constructed. A multi-objective integrated optimization was carried out for each factor. The results showed that, in terms of the order of significance, the influence of each factor on the impurity rate was as follows: cleaning sieve vibrational frequency > clamping height > forward speed > peanut picking roller rotational speed. The order of significance of the influence of each factor on the loss rate was as follows: peanut picking roller rotational speed > forward speed > clamping height > cleaning sieve vibrational frequency. The optimal combination of parameters was a forward speed of 0.85 m/s, clamping height of 190 mm, peanut picking roller rotational speed of 550 rpm, and cleaning sieve vibrational frequency of 590 cpm. Under these conditions, the impurity rate of 2.62% and the loss rate of 2.05% were obtained, which effectively reduced the impurity rate and loss rate and met the quality requirements of Chinese peanut mechanized harvesting operations. The results of this study can provide a basis for the improvement and optimization of the 4HLB-4 half-feed four-row peanut combine harvester and the optimization of its operating parameters. Full article

Targeting the problems of low precision and heavy workload in conventional screening of filled and unfilled grain in single-plant rice testing, a screening system for filled and unfilled grain was designed based on the coupling of the wind and gravity fields. In this study, the motion state of filled and unfilled grain in the flow field and the results of screening were analyzed and combined with aerodynamics. In order to reveal the influence law of the structural and working parameters of the screening system on the screening performance and determine the optimal parameter combination, this study conducted a quadratic regression orthogonal rotating center combination test with four factors and three levels based on the DEM–CFD coupling method. The relationship between air inlet wind speed, air cross-section shape, horizontal distance, vertical distance, and removal rate was studied. The results showed that, in a certain range, the removal rate was positively correlated with the section width of the outlet, positively correlated with the wind speed, and negatively correlated with the vertical distance and horizontal distance of the seed-drop outlet. The optimization results showed that, when the section width of the outlet was 75.44 mm, the wind speed was 8.90 m·s⁻¹, the transverse distance was 198.78 mm, and, when the vertical distance was 34.87 mm, the screening rate of the screening system could reach 99.6%. Full article

The problems of the uneven strip shape and low efficiency of tea de-enzyming and carding machines in the working process were addressed by analyzing the trajectory of tea particles and establishing a force model diagram of tea particles in the pot slot. The three-dimensional geometric model of the tea de-enzyming and carding machine was drawn using UG software, and the simulation model of tea particles was established using EDEM software. The work efficiency of the tea de-enzyming and carding machine was improved, and the rate of broken tea was reduced using the EDEM software to simulate the movement of tea particles in the pot slot under different heights of the convex bar, pot slot angle of inclination, and number of slots. The average velocity and interaction force curve of tea particles were obtained. The influence of the number of slots, the inclination angle of the slot, and the height of the convex bar on the effect of tea into strips were verified using a scheme design based on the quadratic regression orthogonal combination rotation test, and experimental research based on three factors and three levels was carried out. Design-Expert 11 software (Stat-Ease, Minneapolis, MN, USA) was used to optimize the response surface and analyze the regression model of the relevant test data. The 6CSL-800 tea de-enzyming (Anji Yuanfeng Tea Machinery Co., Ltd., Huzhou, China) and carding machine (Anji Yuanfeng Tea Machinery Co., Ltd., Huzhou, China) was used as the verification test prototype, six sets of verification tests were carried out, and the test results showed that the maximum value of the strip rate index and the minimum value of the broken tea rate index were obtained. The order of the indicators affecting the bar-type rate and broken tea rate of the de-enzyming and carding machine from high to low is as follows: the height of the convex bar, the inclination angle of the slot body, and the number of slots bodies. When the height of the convex bar was 10 mm, the inclination angle of the slot was 90°, the number of slots was 12, the bar-type rate was 89.45%, and the broken tea rate was 1.63%. The prediction results of the regression model of the bar-type rate and broken tea rate of the tea de-enzyming and carding machine were verified by employing six sets of control tests with the 6CSL-800 tea de-enzyming and carding machine as the validation test prototype. The actual values of the bar-type rate obtained from the six sets of control tests were 88.19%, 90.37%, and 87.33% (1,2,3 group), and the actual values of the broken tea rate were 1.66%, 1.69%, and 1.61% (4,5,6 group), with average values of 88.63% and 1.65%. The control test was basically consistent with the results of parameter optimization. The processed finished tea has good quality, which can provide theoretical reference for the optimization and design of tea de-enzyming and carding machines and similar tea machines in the future. Full article

In view of the need to remove empty cells and unqualified seedlings for automatic transplanting of leafy vegetable seedlings, this paper proposes a method to detect the growth parameters of leafy vegetable seedlings by using machine vision technology. This method uses the image processor PV200 to perform image grayscale, threshold segmentation, corrosion, expansion, area division, etc. to obtain the pixel value of the leaf area of the seedling and compare it with the set standard value, which provides guiding information for eliminating empty cells and unqualified seedlings. Lettuce seedlings at 17 days, 20 days, and 22 days of seedling age were used as the test objects, and the growth status and test results of the seedlings were analyzed to determine the optimum seedling age for transplanting. The test results show that there is basically no leaf cross-border between the lettuce seedlings at the age of 17 days, the average pixel area of the leaves is 3771.74, and the detection accuracy rate is 100%; the seedlings at the age of 22 days grow 5–6 leaves, the detection accuracy of unqualified seedlings and qualified seedlings was 62.50% and 88.16%, respectively, and the comprehensive detection accuracy was 85.71%. The comprehensive detection accuracy rate showed a downward trend with the increase of seedling age, mainly due to the partial occlusion between leaves. The transplanting of leafy vegetable seedlings is a sparse transplanting operation, and the seedling spacing increases after transplanting. Therefore, the detection of seedlings in the process of transplanting can greatly improve the recognition accuracy and solve the problem that the leaves of the seedlings in the seedling tray are obscured by each other and affect the detection accuracy. The research results can provide a theoretical basis and design reference for the development of the visual inspection system and the transplanting actuator of the leafy vegetable seedlings transplanting robot. Full article

Existing smart lawnmowers, while convenient to use, have significant limitations, such as a lack of manoeuvrability on uneven agricultural grassland (constraint 1), high charging frequency (constraint 2) and low local market penetration (constraint 3). Although the effectiveness of the theory of inventive problem solving (TRIZ) has been demonstrated in several design studies, there also seems to be a lack of research addressing the design difficulties of smart lawnmowers using this method. With the use of the TRIZ method, this study seeks to conceptually design a smart lawnmower for uneven grassland. Tools from TRIZ were used, including cause-effect chain analysis, technical contradictions, physical contradictions, and substance field modelling. In developing a design concept, constraints were solved by inventive principles, separation strategies and standard inventive solutions. For constraint 1, the following solutions were chosen with the appropriate principles: using larger wheels (#17, another dimension: using a second or third dimension), a pivot design (#30, flexible shell: replacing rigidity with flexibility and movability) and replacing the motor with one that has more power or torque. For constraint 2, the following solutions were chosen: to reduce weight, add holes in the mower housing (#31, porous materials: making an object porous or adding porous elements) and attach a solar panel to recharge batteries with solar energy (#28, mechanical substitution: using electric, magnetic or other fields to interact with object). Using other materials or technologies to minimise costs (#13, the other way around: using the opposite way) and a modular design concept to reduce maintenance costs (#1, segmentation: dividing an object into independent parts) were the chosen ways to solve constraint 3. Conceptualisation and design analysis were also performed. Although the effectiveness of the concept is unclear, these suggestions are supported by previous research and could potentially solve some of the problems with smart lawnmowers. Full article

Sandy clay loam has the characteristics of both sand and clay. Because of these characteristics, both frictional resistance and adhesive resistance occur between the soil and tillage tool. The combined effect of the two frictional forces increases the external friction angle between the soil and tillage tool, thus increasing the working resistance. To address this issue, this study investigated the coupling effect of high pressure and hot air on the external friction angle by using a self-developed device to measure the external friction angle. Test results showed that high-pressure air between the soil and tillage tool formed a high-pressure air curtain layer which acted as a lubricant, thereby reducing the external friction angle. The external friction angle decreased as the airflow pressure increased. The reduction in the moisture content of the subsoil to less than 30% by the high-pressure hot air reduced the resistance between the soil and tillage tool. The approach with the high-pressure hot air curtain was verified in tests on a subsoiling shovel; the working resistance of the shovel under high-pressure hot air was reduced by 14.8%, demonstrating that this approach was effective in reducing the working resistance of the shovel. Full article

When sowing with a wide boundary under full rice straw retention in the rice–wheat rotation area of China, conventional fertilization methods have some problems, such as a low fertilizer utilization rate, heap soil around a buried fertilizer device, or blocked fertilizing orifice. Firstly, combined with theoretical analysis, discrete element numerical simulation technology, and central composite test method, the wide-boundary fertilization device for wheat wide-boundary sowing was designed. Then, with the coefficient of variation for particle uniformity (CVPU) as the response value, the central composite experiment was carried out on the key structural parameters (focal length coefficient, lateral span, tilt angle, and ground clearance) of the wide-boundary fertilization device by EDEM software. Finally, the influential rules of core factors of the device on the CVPU were analyzed by Design-Expert software; then, the optimal parameter combination was determined and verified by a field test. The results showed that all factors had significant effects on the CVPU. The primary and secondary factors affecting the CVPU were the tilt angle, lateral span, focal length coefficient, ground clearance, tilt angle × ground clearance, and lateral span × ground clearance, in which there were certain interactions between the tilt angle and ground clearance and lateral span and ground clearance. When the focal length coefficient, lateral span, tilt angle, and ground clearance were 1.5, 60 mm, 30°, and 192 mm, respectively, the lateral was minimum. In this case, the theoretical value and field test value were 14.11% and 17.63%, respectively. The field test value is consistent with the theoretical calculation value. This study could provide references for the design of a fertilizer-spreading device with a wide boundary. Full article