Rice is the second most important cereal in the world after wheat. Threshing is one of the most essential steps in the rice harvesting process. Previously, the drum rod toothed longitudinal axial-flow threshing device has been designed to reduce the blockage of the thresher and threshing power consumption. Specifically, the power consumption of the drum-shaped threshing cylinder can be reduced by 5% to 15% on average, compared with the traditional cylindrical one. Previous work has focused on the structural design of drum-shaped threshing cylinders. But it is still lacking in the uniformity of axial loads on the drum-shaped threshing cylinder. At the same time, the current rice combine harvester threshing and separating devices are focused mostly on the structural improvement and optimization of working parameters, with respect to the performance indicators, such as threshing power consumption, harvesting yield, entrainment loss, unthreshing rate, and crushing rate. The threshing power consumption is mostly measured directly by the power consumption detector during the bench test. Only a few studies have been reported to measure the threshing power consumption, where the axial load uniformity of the drum has been quantified to optimize the rod tooth and drum structure form. In this study, the rod teeth of a drum-shaped threshing cylinder were optimized to improve the axial load uniformity of the drum-shaped threshing cylinder for a higher reduction in power consumption. The impact mechanics model of rod tooth and rice grain was established to determine the structural parameters of the rod teeth that affected the axial load uniformity of the drum, including the diameter of the rod tooth and the threshing gap. Theoretical analysis was implemented to clarify the influence of rod tooth diameter and length on the threshing power consumption. The bending angle of the elbow rod tooth and closed bow tooth was calculated to be set at 45° for better consistency of the threshing gap. The structural parameters were determined for the axial load uniformity of drum rollers, including the rod tooth diameter (7-16 mm), and threshing gap (15-30 mm). The optimal structural parameters were determined with the smallest coefficient of variation in the axial load uniformity as an indicator. A series of simulation tests were conducted to investigate the influence of rod tooth diameter and threshing gap on the axial load uniformity of cylindrical rod tooth, elbow rod tooth, and closed bow tooth drum. The results showed that the axial load trend of the drum roller with the elbow rod tooth was more uniform than that of the cylindrical rod tooth and closed bow tooth. The optimal structural parameters of the rod teeth were 10 mm rod tooth diameter, and 25 mm threshing gap. A three-factor, three-level Box-Behnken response surface bench test was conducted with the feed rate, threshing cylinder speed, and rod tooth shape as the factors, while the threshing power as the indexes, in order to reduce the threshing power consumption. A regression model was established to optimize the working parameters for the threshing power consumption. The bench test showed that the optimal working parameters of the cylindrical rod teeth drum were achieved in the feeding rate of 1.1 kg/s, and the speed of cylinder 900 r/min under the optimal structure parameters, where the lowest power consumption was 4.61 kW. The optimal working parameters of the elbow rad tooth drum were the feeding rate of 0.95 kg/s, and the speed of cylinder 935 r/min, where the power consumption was 3.58 kW. The parameters of closed arch tooth drum were no longer optimized, due to the weak ability to transport stalks easily for the blockage. The rod tooth of the drum was optimized for the shape of the tooth of the elbow rod. The drum simulation and bench tests were carried out to verify the structure and working parameters before and after the optimization of the cylindrical and elbow rod tooth. The variation coefficient of axial load uniformity of the optimized elbow rod tooth drum was 10.34% lower than that of the cylindrical rod tooth drum. The power consumption was reduced by 7.15%, indicating that the optimized elbow rod tooth effectively reduced the threshing power consumption of the drum for the better performance of the drum. This finding can provide a strong reference to optimize the performance of small longitudinal axial flow harvesters in the hilly mountainous areas in China.

Efficient and low-damage separation of the epidermis (skin/rind/hull) is often required in the deep processing of agricultural products, directly impacting further efficiency and product quality. Factory processing has ever rapidly expanding in recent years, as the large-scale and intensified processing industry accelerates the agricultural products. However, manual operation is heavily confined to the epidermis separation, due to the low efficiency, consistency, and high cost. The automatic equipment can be expected to fully meet the demands of modern processing. Particularly, some characteristics can be commonly found in the agricultural products: irregular shape, individual variation, and high mechanical fragility of the flesh. Existing machinery can be subjected to complex shapes and size variations, leading to low separation precision, damage to flesh tissue, and even low stability during operation. The separation effectiveness can also severely hinder the quality of subsequent processing or direct consumption. Therefore, this study aims to systematically analyze the relationship between the morphological characteristics of different materials (e.g., shape, size, epidermal adhesion properties, and flesh mechanical properties) and the adaptability to epidermis separation, starting from the fundamental scientific question of skin-flesh interfacial bonding mechanisms. A summary was also given on the working mechanisms, typical mechanical implementations, and representative examples of applicable agricultural products for mainstream techniques of epidermis separation. Some treatments included the compressive shelling, tearing-based peeling, frictional comb-brushing, cutting-based peeling, and chemical/high-temperature softening. A systematic review was presented on the mechanical research, in order to improve the high production efficiency and low-damage separation. Furthermore, there were the dynamic mechanical responses of materials during separation, the required separation forces (e.g., peeling force, shear force), and the effective detachment force between flesh and epidermis. Furthermore, the current research and development status of the technologies and equipment was also obtained for the epidermis separation, including the mechanical mechanisms, equipment innovations, and applications. The key technological and equipment advances were also reviewed for the pre-separation processing (e.g., grading pretreatment) and post-separation processing (e.g., sorting, and epidermis recycling). Specifically, the development trends and application prospects of intelligent technologies were explored in the field of epidermis separation. Intelligent equipment was outlined to integrate the machine vision (MV), deep learning (DL), multi-sensor information fusion, as well as the environmental perception and decision-making, in order to enhance the equipment's adaptability and intelligence levels. Finally, some recommendations should be focused on: the highly adaptable and intelligent epidermis separation equipment; the standardized process systems; and the collaborative innovation across the entire industry chain to integrate the raw materials and equipment with the process optimization. This finding can provide a systematic theoretical reference and practical guidance to select the epidermis separation of agricultural products, as well as the key technologies and equipment. It holds significant importance to promote the technological upgrading and high-quality development of product processing in the agricultural industry.

The lotus root is one of the most popular food products in the stem of the lotus plant in Asia areas. Mechanical excavators of lotus roots can be expected to save the cost and labor intensity. However, the existing track float self-propelled excavator cannot fully meet the large-scale production, due to the large overall weight. There are also some difficulties in climbing, turning, and slipping vehicles in the field. In this study, the skid support device was designed to treat the high driving resistance and excess sinking of the crawler float-type excavator of lotus root. The device was installed on both sides of the chassis and hydraulically driven up and down to adjust the position. The gravity of the whole machine was supported to reduce the grounding pressure and sinking depth of the crawler. The passability was also improved as well. The driving performance of the crawler float-type excavator chassis was evaluated after the skid support device was added. The chassis of the crawler float-type excavator was taken as the research object. A new model was also established for the driving resistance and tractive force of the chassis. Theoretical analysis was conducted on the extrusion force between the soil and the ground surface at the front of the skid. The sliding-cutting angle α and milter angle φ were determined to be the main structural parameters of the driving resistance. A skid scale model was constructed for the one-third of original size. The single-factor simulation was carried out using the driving speed and sinking depth in EDEM software. A systematic investigation was made on the influence of sliding-cutting angle α, milter angle φ, driving speed v and sinking depth on the forward resistance. The results showed that the forward resistance decreased with the increase of slip angle α, and milter angle φ, whereas, there was an increase with the increase of driving speed v, and sinking depth. The box-Behnken test was also carried out to explore the influence of slip-cutting angle, milter angle and forward speed on forward resistance. The influencing factors were taken as the sliding-cutting angle α, milter angle φ, and driving speed v, while the forward resistance was the response index. It was found that the driving speed v shared a very significant effect on the forward resistance (P＜0.01). The significant effect of sliding-cutting angle α, milter angle φ, and the square term v₂ of driving speed v on the advancing resistance (0.01＜P＜0.05). The optimal combination of parameters was obtained for the skid structure. Specifically, the least forward resistance was achieved, when the sliding-cutting angle α was 40°, the milter angle φ was 70° and the driving speed v was 0.1 m/s. Correspondingly, the forward resistances were 66.09 and 82.28 N in the simulation and soil bin test, respectively. The soil bin test showed that the skid driving speed and sinking depth had very significant effects on the skid forward resistance (P＜0.01). The skid driving speed and sinking depth were also proportional to the forward resistance, indicating the consistence with the simulation. The field test was carried out on the crawler float-type excavator before and after the skid support device. The resistance torque of the driving motor was reduced by 6.51%, which were 182.15 and 170.30 N·m, respectively. The sinking depth of the chassis was 178.1 and 164.5 mm, respectively, which were reduced by 7.64% than before. The performance of the excavator was outstandingly improved after adding the skid support device. This finding can provide a strong reference for the walking device of the ground machine system in paddy fields.

Automatic transplanting of plug seedling has limited for the two challenges. One is that the broken pot can be caused by the weak twining force between roots and soil, when the end of grippers is inserted into the pot to pick up the seedlings; Two is that the low success rate of seedling picking in the stem-pulling seedling picking mechanism, when the seedling claws clip and pull the stem, due to the weak adhesion force between the pot and the plug. In this study, a seedling picking device was proposed with ejecting pot-clamping stem. The picking up seedling was as follows: The pot was ejected by rod to clip out from the seedling, and then the stem was clamped by seedling clip, while seedling was pulled out of plug tray, seedling shift and releasing clip throwing. A series of tests were carried out on the structure design, the device trial and optimization. Taking "Zhongnong Luheng line pepper 363" plug seedlings aged 35 to 50 days as the object, the stem of plug seedling was tested to obtain the characteristic parameters, stem tensile and stem radial compression mechanical properties; The pot of plug seedling was tested to verify the parameters. The result shows that the maximum drawing force was 3.54-5.38 N, the elastic modulus of the pot was 30.64×10⁻³ MPa, the deformation at the yield point of the pot was 10.87 mm, and the pressure resistance was 12.33 N. The path was optimized for the picking up and throwing seedlings. The optimal path of picking up seedlings stretching along Y direction was 33.98% shorter than that along X direction. The stress models of the pot and stem were established during ejecting and clamping, according to the stem and pot physical properties of pepper plug seedlings. The key parameters of seedling picking up device were designed, including the seedling tray conveying device, the top ejecting device, and the seedling picking up mechanism. An optimal combination of parameters was achieved, where the diameter of the ejecting rod was 15 mm, the height of ejecting pot was 10-20 mm, the height of clamping stem was 20 mm, and the width of the clamping sheet and the width of the seedling clip were both 10 mm. Seedling picking up experiment was carried out on the test bench, where the average total height of plug seedling was 216 mm. The pot moisture content, seedling pick-up frequency, and the height of pot ejecting were used as the influencing factors for the seedling pick-up L9(3⁴) orthogonal experiments. The better growth of the plug seedlings was achieved in the picking up from the ejecting pot-clamping stem. The optimal horizontal combination of factors was determined as well. The damage rate of pot was 1.98% and the success rate of picking up seedling was 98%, when the moisture content was 45%, seedling pick-up frequency was 60 plants/min, and the height of seedling ejecting was 10 mm. Field test was carried out at the working speed of 10 ~ 30 m/min and the picking up seedling frequency of 60 plants/min. The average success rate of seeding pick-up was 93.05%, and the qualified rate of plant spacing was 88.17%. This seedling pick-up device shared the stable seedling pick-up and low damage rate, particularly for the transplanting plug seedlings, such as pepper and tomato. The planter can be expected to install the transplanter for the high-efficient picking up of seedling.

Taro (Colocasia esculenta) is one of the perennial tuberous plants in the Araceae family. The global area of taro harvesting has reached 1.793 7 million hectares in 2022, with a total output of 12.394 5 million tons. The yield per unit area in China has been 2.75 times the world average in the world. The main production regions are situated in the Yangtze River Basin, the Pearl River Basin, and Taiwan Province. Taro can play a crucial role in the process of rural revitalization. However, manual harvesting has been predominant in recent years. It is still lacking in the specialized harvesting equipment for the mechanized production of taro. In a previous study, the bar-type screening device was employed to conduct taro harvesting experiments. The taro root system and the soil have also been adhered, wrapped, and entangled to form a "root-soil composite" structure during operation. This complex matrix can serve as the taro tubers to reinforce the fibers for the roots. Nevertheless, some challenges remain in actual production, including suboptimal soil crushing quality, ineffective root-soil separation, and elevated screening power consumption during mechanized harvesting. Furthermore, the existing bar-type screening device was unable to fulfill the requirement of taro root-soil separation requirements. In this study, the centrifugal rotary root-soil separation device was developed to fully meet the agronomic and harvesting requirements of multi-seed taro. A collision mechanics model of taro root-soil composite was developed for an impact crushing mechanics model of soil blocks. A systematic analysis revealed that the primary influencing factors on the efficacy of root-soil separation were ranked in the descending order of the spring tooth inclination angle, the rotational speed of the screen, and the aspect ratio of the flexible finger. The range of values was determined for the influencing factors after measurement. A discrete element model (DEM) of taro corm-root-soil composite was established using EDEM software, in order to analyze the process of soil fragmentation under impact collisions. The simulation experiment was conducted to couple the EDEM-Recur Dyn platform. A systematic analysis was made to determine the dynamic change of the taro root-soil composite during screening. There were the balance, instability, soil crushing, collision tumbling, and soil shedding. The single-factor test showed that the diameter and length of flexible fingers were 14, and 45 mm, respectively. A quadratic regression orthogonal test was conducted to identify the optimal combination of spring tooth inclination angle, rotary screen speed, and soil feed amount, with the root-soil separation rate and the maximum impact force of taro as the evaluation indices. The optimal combination of parameters was determined using the Design-Expert software. A high root-soil separation rate of 93.36% was achieved in the rotary screen speed of 110.00 r/min and a soil feed amount of 14.00 kg/s at an inclination angle of 16.00°. A series of field tests were conducted to validate the optimal parameters under identical operational conditions. The results indicated that the root-soil separation rate was 92.06%, which differed by 1.39% from the prediction of a regression model. At the same time, the taro damage rate was 4.86%. Five performance tests were conducted using the multiple taro harvester and the traditional bar-type rhizome harvester. The root-soil separation rate of the multiple taro harvester increased by 8.61 percentage points under identical operational conditions, while the damage rate increased by 0.99 percentage points. The centrifugal rotary device of root-soil separation fully met the requirements of root-soil separation of taro. The screening performance was better than the traditional grid-type screening device. The findings can serve as the sound foundation to design efficient and low-loss harvesting equipment in the crushing and separation of root-soil composite for root and tuber crops.

Water chestnuts are aquatic root vegetables in the Asian areas. However, the collision damage can often occur in the mechanical harvesting and post-harvest processing of water chestnuts. In this study, a finite element simulation was conducted on the impact between harvesting machinery and water chestnuts using Ansys software. The impact damage to water chestnuts was identified to enhance the quality of mechanical harvesting and post-harvest treatment. A principal strain failure model was also adopted to accurately simulate the energy dissipation during collision, rather than the existing elastoplastic model. Initially, the average size of the water chestnut was measured using three-dimensional scanner. An appearance model was also created after scanning the samples. Three sections were then divided into: peel, pulp, and top bud. Uniaxial compression tests were conducted to measure and calculate the intrinsic parameters of the flesh and peel of the water chestnut. A comprehensive model of water chestnut was established after selection, thus culminating in the selection of a linear elastoplastic and principal strain failure coupling model. The parameters were calibrated and verified by slab drop tests at three heights. A systematic analysis was also made on the evolution of stress, energy, and rupture of the coupled model during drop. The screening device of the harvester also impacted the collision damage to water chestnuts. A simplified rod model was developed to investigate the impact of collision on the water chestnuts under various conditions. To this end, a three-factor, three-level and full-factor collision simulation test was conducted in the fall heights of 200, 400, and 600 mm, collision contact surface diameters of 16, 20, and 24 mm, and collision materials of structural steel, PVC, and rubber. A three-factor, three-level full-factor rod collision simulation test was also to assess the damage susceptibility of water chestnut to bruising, softening, and rupture. The analysis of variance (ANOVA) was employed for the empirical formula of damage susceptibility under different materials. The elastic modulus, yield strength, and tangential modulus of water chestnut pulp were measured as 7.916, 0.586, and 4.554 MPa, respectively. The principal strain of failure was determined to be 0.098. The impact damage distribution was simulated with the failure mesh volume and the stress interval volume exceeding 0.60 MPa. The relative errors in the bruise volume, rupture volume, and dissipated energy were determined to be 7.18%, 8.98%, and 6.62%, respectively. Therefore, the model was expected to describe the mechanical properties, rupture behavior, and energy dissipation of water chestnut under impact load. The rod impact test demonstrated that the drop height of the water chestnut exhibited a direct linear relationship with its damage susceptibility. The elastic modulus of the collision contact material also exerted a substantial influence on the damage. The impact of the contact diameter was found to be associated with the nature of the contact material. In the case of collisions with the structural steel, the damage exhibited an initial increase and subsequent decrease with the increasing diameter. Conversely, the damage decreased with the increasing diameter in collisions with the PVC and rubber. The damage to 2, 4 and 6 mm rubber-coated rod teeth was reduced by 9.3%, 13.7%, and 20.9%, respectively, compared with the unwrapped rod teeth. These findings can offer a valuable reference on the quality of water chestnut during mechanical harvesting.

In order to address the issues of narrow seeding adjustment range and low accuracy of grain placement in the existing rice seeders, a mechanically and pneumatically adjustable precision hole-type seeder is designed. It is primarily composed of a seeding disk, air chamber, seed box, and seed discharge device. The design incorporates a symmetrical structure with dual disks and dual casings, enabling both single-sided and double-sided single-row and synchronized seeding. Based on theoretical analysis of seed charging, seed protection, and seed release, the following parameters were determined: seeding disk diameter of 192 mm, suction hole diameter of 1.48-1.52 mm, suction hole spacing of 3.04-9.41 mm, type hole distribution circle radius of about 62.1-77.0 mm, type hole diameter of 9 mm, stirrer plate length of 4.705-9.410 mm, and stirrer plate inclination angle of 0°-30°. Using a coupled simulation method of EDEM-Fluent, the impact of different type hole distributions, stirrer plate lengths, and inclination angles on seeding performance was analyzed. The results indicate that the main and secondary influencing factors on seed charging qualification rate are type hole diameter, stirrer plate inclination angle, and stirrer plate length. The optimal performance is achieved with a type hole diameter of 6 mm, stirrer plate length of 5 mm, and stirrer plate inclination angle of 10°, resulting in a seed charging qualification rate of 71.42%. Furthermore, Fluent software was utilized to analyze the influence of different suction hole spacings, diameters, and air chamber radii on seeding performance. The results revealed that the suction of rice seeds by the hole can be better realized with a suction hole spacing of 6 mm, a suction hole diameter of 1.5 mm, and an air chamber radius of 62 mm, at which the average negative pressure in the suction hole center was about 2824.56 Pa. A bench test and a field test were further performed on the device. The results showed that increasing the number of type holes and suction holes can contribute to more stable regulation of the seeding amount. The optimal single-sided seed metering could achieve a maximum qualified rate of 82.5%, a missing rate of 12.5%, and a repeating rate of 5%; while the optimal double-sided seed metering could obtain a maximum qualified rate, missing rate, and repeating rate of 72.5%, 15%, and 12.5%, respectively. This adjustable precision seeder can meet the requirements of precision sowing of Huanghuazhan rice varieties, and the research findings can provide reference for the structural optimization of precision rice seeders.