Table grapes are high-value horticultural fruit plant in modern agriculture. Yet their postharvest packaging and grading remain labor-intensive, resulting in low efficiency, excessive costs, and fruit damage. Existing equipment, primarily for general fruits, cannot fully meet the specific requirements of table grapes, such as thin skin, soft pulp, berry drop, and double-bag packaging. In this study, a special double-bag packaging and grading machine was developed for table grapes. Feeding, double-bag packaging, bag closing, weighting, and grading were integrated to improve the postharvest efficiency and quality of table grapes. The whole machine was composed of a feeding device, a transparent bag and a paper bag packaging system, a bag-closing, a weighing and grading device, as well as a frame. In the feeding device, a single-cylinder driven symmetrical linkage structure was adopted with universal ball joints and flexible buffer sleeves. The stable opening and closing of the material gates were synchronously realized to reduce mechanical interference and jamming, leading to the accurate and non-damaged feeding of grape clusters into the packaging unit. The double-bag packaging realized the mechanical picking, opening, and covering of transparent inner bags and paper outer bags after the cooperative movement of vacuum suction cup groups and pneumatic cylinders. Corrugated vacuum suction cups were selected for their adaptability to flexible packaging materials. A linear arrangement was adopted to calculate adsorption force and layout size. Reliable grabbing and stable opening of bags were fully met the size requirements of grape clusters. The bag-closing device also simplified the gathering gripper into a crank-slider mechanism. The wire-tying machine was cooperated to effectively tighten the bag mouth for the firm and consistent sealing, thus improving the packaging and appearance quality. The weighing and grading device was equipped with an HX711 cantilever load cell and a synchronous belt slide mechanism. Real-time and high-precision quality detection was realized during conveying. Grape clusters were then transported to the grading positions, according to the preset quality grading standards. Conveying, weighting, and grading were integrated after optimization. In terms of control system, a distributed control architecture was adopted using STM32 microcontroller. Multiple microcontrollers were responsible for the different execution modules. The action timing of each component was coordinated via serial communication. The connection time of each process was optimized to improve the overall operation efficiency and stability of the control system, indicating better scalability for function expansion. A series of tests were conducted to verify the performance of a double-bag packaging and grading prototype machine for table grapes under indoor windless conditions. According to table grape quality grading standards, packaging qualification rate, grading accuracy, and average processing time were selected as evaluation indices. A total of 50 trials were finally repeated with full-process video recording. The results showed that the packaging qualification rate reached 92.00%, the grading accuracy was 94.00%, and the average processing time per grape cluster was 58.00 s. All performance indices met the technical and efficiency requirements of practical postharvest production. Feeding, double-bag packaging, bag closing, weighing, and grading were stably integrated to effectively reduce labor input and mechanical damage to the fruit, compared with the manual operation. The double-bag packaging and grading machine can effectively combine packaging and grading functions during table grape postharvest. The parameters can be adjusted, such as suction cup spacing and packaging size, particularly for the structural adaptability into the similar postharvest fruits and vegetables.

The cold and dry winter climate has posed severe threats to the freezing damage and even death to grapevines in the open-field grape cultivation areas, particularly in northern China. It is also essential to prune and lay down the vines before winter for the appropriate cold protection, especially for the high-quality and yield of grapes in the following year. Among them, the cold-proof covers have been widely adopted for cold protection, due to the moisture retention, thermal insulation, reusability, and effective prevention of sandstorms. A low-cost and efficient measure is often required for sand control. However, the current manual laying and rolling operations of cold-proof covers have also limited the large-scale production in recent years. In this study, a multifunctional integrated machine was designed for the rolling and laying operation on the cold-proof covers. The high operation efficiency and low labor intensity were also achieved in the spring rolling and winter laying of cold-proof covers in cold-proof areas. Several components were mainly composed of the machine: a main frame, an auxiliary frame, a hydraulic system, a winding core, and a cover spreading frame. The whole machine was connected to the rear of a tractor using the three-point suspension. The high-efficiency rolling of the cold-proof cover was realized in the reverse forward rolling mode; The self-weight of the cold-proof cover drove the winding core to rotate during laying, particularly for the automatic laying. A flexible media model of the cold-proof cover was established using RecurDyn/MTT3D (Media Transport Toolkit 3D). The modeling parameters were calibrated after the simulation. The generation mechanism of wrinkles during rolling was analyzed using simulation and theoretical research. An auxiliary flattening scheme was proposed with the cover spreading frame. Taking the height of the winding core from the ground, the depression angle, and the flattening angle of the cover spreading frame as the experimental factors, the Box-Behnken experimental design was adopted for parameter optimization. The optimal operation parameters were obtained as follows: The height of the winding core from the ground was 1 400 mm, the depression angle of the cover spreading frame was 10°, and the flattening angle was 120°. The flattening rate reached 98.2% with a traction resistance of 335.7 N after simulation under the optimal parameters. A prototype was manufactured for the field experiments. The cold-proof cover was effectively distributed to both sides under the action of the cover spreading frame. The winding was relatively flatly rolled during operation. The actual flattening rate was 97.6%, with an error of only 0.6 percentage points, compared with the simulation. The rolling efficiency of the machine was 21.1 seconds per cover, and the laying efficiency was 16 seconds per cover. The machine can fully meet the operational requirements of rolling and laying cold-proof covers for grapes in northern China. The findings can offer technical references on cold-proof cover rolling and laying machinery.

Grapevine lifting onto trellises has been one of the most important procedures during grape production in the spring. Mechanizing this procedure is crucial to the grape industry in northern China. In this study, a star-wheel finger-chain device was designed for grapevine lifting during mechanized trellising in spring. The device consisted of a star-wheel finger-chain and a crank-rocker mechanism. Among them, the vine picking mechanism was used to lift the grapevines from the ground during operation, and then the star-wheel finger-chain mechanism was used to raise them at the target vine-lifting angle. Theoretical analysis was carried out to determine the structural parameters of the key components, such as the length of the finger, the distance between fingers, and the length of the chain plate. The Multi-Body Dynamics (MBD) was used to simulate the interaction between the device and the grapevines. A simulation model was established in the RecurDyn software. The rotational speed of the crank-rocker, the rotational speed of the sprocket, the spring pre-load, and the chain plate inclination angle were selected as the experimental factors. The average lifting angle and the coefficient of variation of the angle were used as the evaluation indexes. A Box-Behnken (BBD) simulation experiment was conducted to optimize the operating parameters. Finally, the soil bin tests were carried out to verify the performance of the device under the optimal parameters. The structural parameters of the key components were determined after tests. Specifically, the length of the finger was 130 mm, the grabbing gap was 80 mm, the distance between adjacent fingers was 177.8 mm, the chain plate inclination angle was 45°, and the effective conveying length of the finger-chain was 700 mm. Simulation results showed that the influencing factors on the average lifting angle were ranked in descending order: the rotational speed of the sprocket, the rotational speed of the crank-rocker, the spring pre-load, and the chain plate inclination angle. In the coefficient of variation of the angle, the influencing factors were ranked in descending order of the rotational speed of the crank-rocker, the spring pre-load, the rotational speed of the sprocket, and the chain plate inclination angle. The optimal combination of the parameters was obtained: a crank-rocker rotational speed of 51 r/min, a sprocket rotational speed of 66 r/min, a spring pre-load of 27 N, and a chain plate inclination angle of 45°. As such, the average lifting angle in the simulation test was 44.9° with a coefficient of variation of 9.83% under the optimal combination. In the soil bin test, the average lifting angle was 44.7° with a relative error of 0.44%, compared with the simulation. The coefficient of variation was 6.76% with a difference of 3.07 percentage point from the simulation. The pole-picking and finger-support device was achieved in the step-by-step lifting of grapevines. The MBD model was established to accurately simulate and optimize the lifting device. The stable lifting angle and excellent uniformity can be expected to fully meet the requirements of grapevine trellising. The finding can also provide a strong reference to an integrated machine for the grapevine lifting and tying in the grape industry.

Grapevines can be prevented from winter freezing damage on the open-field trellis in the grape planting areas of northern China. It is necessary to prune and lay down the vines, then bury them in the soil for cold protection. Once the climate warms in spring, it is often required for the soil clearing and vine unearthing operations before the grape buds sprout after the temperature warms up. The traditional clearing can be implemented on the soil first, and then unearthing vines. The critical issues can suffer from: the low manual operation efficiency, a narrow operation window (typically limited to 1 week), and a high risk of vine damage. However, it is unclear about the positions of the buried vines during soil clearing. Additionally, the timing constraint (while unearthing too early risks frosted the injury, while too late caused the bud germination in the soil) exacerbated the labor intensity and operational pressure in vineyards. In this research, the unearthing machine was developed to improve the operational efficiency for the reduction of the vine injury and extend the time window for the subsequent soil-clearing tasks. A double-spade side-mounted grapevine excavating machine was designed using an unearthing strategy. The vines were extracted from the soil ridges before removing protective soil. The key components included a crank-rocker mechanism with dual spades, a spring-loaded suspension system, and adjustable depth wheels. The trajectory of the spade tip was optimized for the effective penetration and lifting of the vines. The kinematic parameters of the mechanism were determined to consider some constraints, such as the minimum transmission angle and soil ridge geometry, according to the coordinate system and mathematical modeling. A RecurDyn-EDEM coupling simulation was conducted to validate the design. The multi-body dynamics (MBD) and discrete element method (DEM) were integrated into the soil-spade interactions. A Plackett-Burman experiment was carried out to screen seven parameters (e.g., spade angles and operating speed) for their impact on the maximum crank torque. Significant factors (end angle, digging angle, and excavating angle) were further optimized using the Box-Behnken test. The torque was then optimized to minimize using the response surface method. A prototype was fabricated and then tested in field conditions with the sandy loam soil (moisture 8%-14%, and compactness 56-133 kPa). Performance metrics included the crank torque, vine exposure rate, and damage rate. Torque data were collected using a ZH07 sensor. While the vine exposure rate and damage rate were visually inspected post-operation. The optimal parameters of the spade were achieved in the end angle of 130°, digging angle of 3°, and excavating angle of 15°. Simulation results showed the minimum average crank torque of 62.3 N·m. Field trials verified the efficacy of the machine, with an average torque of 64.9 N·m (4.2% error from simulation). The mean vine exposure rate reached 86.8%, with a mean damage rate of 6.9%, due primarily to the vine entanglement during lifting. The vines were visibly exposed during post-unearthing, indicating the safer and more efficient subsequent soil removal. A double-spade side-mounted excavating machine was successfully developed and validated for the grapevine unearthing. The optimal design balanced the mechanical efficiency and vine protection, fully meeting the operational requirements in the northern Chinese vineyards. The finding can offer a practical solution to reduce the labor intensity, in order to extend the unearthing window for minimal crop damage.

Fertilizer application has been one of the most important facilities to advance agricultural mechanization. Particularly, manual fertilization cannot fully meet the large-scale production in recent years. In this article, a chain reversal trenching and application device was presented for the organic fertilizer in orchards, in order to enhance the trenching depth and uniform fertilization. A reverse-chain trenching mechanism was employed with a fixed trenching blade that moved in the opposite direction of the chain. The soil cutting and simultaneous backfilling were allowed within the trench, as the device progressed. A trenching depth of up to 600mm was achieved in the chain trenching mechanisms. The separate backfilling was reduced to leave no visible trenches on the surface after completion. This design was also a streamlined operation. The mathematical analysis of the trenching blade was conducted to establish a mathematical model using Cartesian coordinate transformations. The relationship equation was derived for the cutting angle. Optimal angle parameters were also provided. According to the trenching depth analysis, the hydraulic adjustment cylinders were selected for the trenching device. A scraper-type fertilizer application mechanism was adopted to develop the discrete element simulation models for both upright and sideways fertilizer application modes. The fertilizer distribution patterns were analyzed under the two modes. While both modes were similarly distributed fertilizer, and the forward-facing mode was more suitable for the operations with the larger fertilizer widths, while the sideward-facing mode was with the smaller fertilizer widths. In the two fertilizer application modes, the sideways application mode had better uniformity, especially at the lower forward speeds. Therefore, the application mode of sideward-facing fertilizer was selected to ensure that all organic fertilizer accurately fell into the trench. A single-factor experiment was carried out to explore the effects of scraper height, angle, and spacing on the normal contact force and coefficient of variation. All three parameters shared a significant impact on the coefficient of variation. In a coefficient of variation of less than 15%, the optimal height, angle, and spacing of the scraper were selected to minimize the normal contact force, resulting in values of 20 mm, 90°, and 180 mm, respectively. According to these optimal parameters of the scraper, the simulation was conducted to yield a coefficient of variation of 6.02% and a normal contact force of 9.03 N, both of which were lower than those before optimization. Subsequently, a physical prototype was fabricated and field-tested. An average coefficient of variation of 8.34% was obtained for fertilizer distribution, indicating better uniformity. Furthermore, the maximum and minimum fertilizer application tests showed that the quantities ranged from 0.8 to 6 kg/m, thus meeting the fertilization requirements of different plots. The trenching performance tests show that the average trenching depths of two operations were 616.0 and 624.4 mm, respectively, with stability coefficients of 93.57% and 92.58%, respectively, both exceeding 90%. The average trenching widths were 305.4 and 295.4 mm, respectively, with consistency coefficients of 96.16% and 95.04%, respectively, both exceeding 95%. Therefore, the device exhibited excellent performance in the fertilizer distribution and trenching operations, fully meeting the agronomic requirements. The findings can provide a new tool for the deep application of organic fertilizers in orchards, indicating the promising potential prospects. Innovative design and efficiency can also offer valuable insights into the agricultural fields.

Grapevine picking-up machinery is a high demand in the open-field grape-producing regions of northern China during spring. In this study, the grapevine picking-up mechanism was proposed for the lifting operation using a crank-rocker mechanism. The mechanism was mainly consisting of a frame, crank rocker structure, pushing bar, picking bar, spring, and vine fender. Grapevines were lifted from the ground to the given angle with a simple and reliable structure. The structure of crank rocker was used to constrain the movement trajectory of the picking bar. The pushing bar was used to gather the grapevines, and then the picking bar was lifted them. MATLAB software was also utilized to optimize the parameters of the trajectory curve. An optimal set of structural parameters was achieved for the picking bar. The length of the crank was 160 mm, the length of the link-rod was 480 mm, the length of the rocker was 340 mm, and the length of the base frame was 600 mm. The endpoint coordinates of picking bar were relative to the uBv coordinate system as (1 070 mm, -250 mm). According to multi-flexible-body dynamics (MFBD) simulation, the finite element (FE) flexible body model was established for the grapevines and picking-up operation. A Box-Behnken simulation experiment was designed to analyze the impact of three parameters (forward speed, spring preload force, and crank rotational speed) on the grapevine picking-up through the software RecurDyn. Regression significance analysis of the experimental data was conducted using Design-Expert software, with the average angle and the coefficient of angle variation as the evaluation indices. The results showed that all three test factors shared a significant effect on the average angle, while the forward speed posed a significant effect on the coefficient of angle variation. Among the interaction factors, the spring preload force and the crank rotation speed had a significant impact on the average angle, while the spring preload force and the crank rotational speed had a significant impact on the coefficient of angle variation. Among the quadratic factors, only the square of the forward speed and the crank rotational speed had a significant effect on the coefficient of angle variation, while the rest factors had no significant effect. The maximum average angle and the minimum coefficient of angle variation were obtained after optimization. Consequently, the best combination of working parameter was determined for the machine: the forward speed was 0.2 m/s, spring preload force was 128 N, and crank rotation speed was 67 r/min. As such, the average angle of grapevines was 40.6° in RecurDyn, and the coefficient of angle variation was 6.0%. Finally, the prototype was manufactured to conduct the soil bin tests. There was the essentially consistent data with the optimization. The relative error between soil bin tests and simulation was 6.4%, and the mean of the coefficient of angle variation was 14.8%, fully meeting the operational requirements for picking up grapevines. This finding can be expected to serve as a strong reference in the integrated machines for grapevine lifting and tying.