Search Results (47)

Jujubes have a beautiful taste, and high nutritional and economic value. The planting area of dwarf and densely planted jujubes is large and shows an increasing trend; however, the mechanization level and efficiency of fresh jujube harvesting are low. For this reason, our research group conducted a study on mechanical harvesting technology for fresh jujubes. A pneumatic jujube harvester was designed. This harvester is composed of a self-regulating picking mechanism, a telescopic conveying pipe, a negative pressure generator, a cleaning mechanism, a double-chamber collection box, a single-door shell, a control assembly, a generator, a towing mobile chassis, etc. During the harvest, the fresh jujubes on the branches are picked under the combined effect of the flexible squeezing of the picking roller and the suction force of the negative pressure air flow. They then enter the cleaning mechanism through the telescopic conveying pipe. Under the combined effect of the upper and lower baffles of the cleaning mechanism and the negative-pressure air flow, the fresh jujubes are separated from impurities such as jujube leaves and branches. The clean fresh jujubes fall into the collection box. We considered the damage rate of fresh jujubes, impurity rate, leakage rate, and harvesting efficiency as the indexes, and the negative-pressure suction wind speed, picking roller rotational speed, and the inclination angle of the upper and lower baffles of the cleaning and selection machinery as the test factors, and carried out the harvesting test of fresh jujubes. The test results show that when the negative-pressure suction wind speed was 25 m/s, the picking roller rotational speed was 31 r/min, and the inclination angles of the upper and lower baffle plates for cleaning and selecting were −19° and 19.5°, respectively, the breakage rate of fresh jujube harvesting was 0.90%, the rate of impurity was 1.54%, the rate of leakage was 2.59%, and the efficiency of harvesting was 73.37 kg/h, realizing the high-efficiency and low-loss harvesting of fresh jujubes. This study provides a reference for the research and development of fresh jujube mechanical harvesting technology and equipment. Full article

Camellia oleifera is one of the four largest woody oil species in the world, with more than 5 million hectares planted in China alone. Reducing bud damage and improving harvesting net rate and efficiency have become the key challenges to mechanized harvesting of Camellia oleifera fruits. This paper presents a novel comb-spiral impact harvesting device primarily composed of four parts, which are lifting mechanism, picking mechanism, rotating mechanism, and tracked chassis. The workspace of the four-degree-of-freedom lifting mechanism was simulated, and the harvesting reachable area was maximized using MATLAB R2021a software. The picking mechanism, which includes dozens of spirally arranged impact pillars, achieves high harvesting efficiency through impacting, brushing, and dragging, while maintaining a low bud shedding rate. The rotary mechanism provides effective harvesting actions, and the tracked chassis guarantees free movement of the equipment. Simulation experiments and field validation experiments indicate that optimal performance can be achieved when the brushing speed is set to 21.45 r/min, the picking finger speed is set to 341.27 r/min, and the picking device tilt angle is set to 1.0°. With these parameters, the harvesting quantity of Camellia oleifera fruits is 119.75 kg/h, fruit shedding rate 92.30%, and bud shedding rate as low as 9.16%. This new model for fruit shedding and the comb-spiral impact harvesting principle shows promise as a mechanized harvesting solution for nut-like fruits. Full article

Telemetry systems are increasingly finding applications in agriculture for a variety of tasks. These systems assist farmers in optimizing farm processes. By leveraging these technologies, energy resources can be used more efficiently, leading to reduced environmental pollution. The primary objective of this research is to analyze telemetry data and explore ways to enhance the efficiency of combine harvesters (CHs). For this study, data from the Lexion 750 TT CH equipped with a crawler chassis was selected. Harvesting operations were conducted across fields growing popular plant types in Lithuania, including wheat, barley, rapeseed, oats, corn, and beans. The selected CH was also equipped with a remote monitoring system for tracking machine parameters. During the research, the structure of the time distribution of the work and the consumed fuel was analyzed. The highest operational efficiency—defined as the proportion of time spent on productive harvesting tasks—was 78%, observed during the oat harvest, when the unloading while harvesting, unloading while idle, harvesting, and headland turns were 3%, 2%, 64%, and 9%, respectively. The lowest efficiency, 56%, occurred during wheat harvesting. It was found that harvesting 899.32 ha of six different plant species with the tested CH produces 46.11 t of GHG emissions in CO_2eq. The largest part of the emission in CO_2eq was released during direct harvesting, with the engine operating at 1800–1900 min⁻¹. However, as much as 30% of the time and 11.2% of fuel was consumed by the CH for non-harvesting activities. In conclusion, attention should be paid to reducing the inefficient use of CH time. In this way, technological operations would not only be carried out more rationally, but also environmental pollution would be reduced, and in the case of this study, we could potentially reduce CO_2eq emissions by more than 10%. Full article

Terpenoids, which are widely distributed in nature, possess diverse biological activities, physiological functions, and economic values. They are extensively exploited by plants and microorganisms. However, the abundance of terpenoids in natural hosts is extremely low, making it difficult to meet the market demands. In recent years, along with the advancement of metabolic engineering and synthetic biology, it has become feasible for microorganisms to produce exogenous terpenoids sustainably. Cyanobacteria and other photosynthetic microorganisms have attracted growing attention due to their capacity to produce terpenoids by harnessing light and carbon dioxide. In this article, we comprehensively summarize the biosynthetic pathways of terpenoids and the progress in utilizing cyanobacteria as chassis for the production of terpenoids, and further discuss strategies for augmenting the yields of terpenoids. Full article

China’s orchards cover vast areas, predominantly located in hilly regions where the terrain is complex, making mechanized operations difficult to implement effectively. This results in a low comprehensive mechanization rate in the fruit planting industry, severely restricting the development of agricultural mechanization in China’s hilly areas. This article first explains the principles of automatic leveling technology, summarizing the characteristics and suitable application scenarios of different leveling technologies in the context of actual work in hilly orchards. It then provides an overview of the research progress in automatic leveling machinery for orchards from the perspectives of power machinery, operation platforms, and operating tools, analyzing the leveling control schemes of various orchard operation machinery equipped with automatic leveling features tailored for hilly orchard work. This article explores key technologies for chassis leveling, summarizes universal leveling mechanisms and control algorithms, analyzes the numerous challenges faced by the current development of automatic leveling technology for orchard machinery, and offers targeted development suggestions. Full article

To address the challenges of low pesticide utilization, insufficient automation, and health risks in orchard plant protection, we developed an autonomous spraying vehicle using ArduPilot firmware and a robot operating system (ROS). The system tackles orchard navigation hurdles, including global navigation satellite system (GNSS) signal obstruction, light detection and ranging (LIDAR) simultaneous localization and mapping (SLAM) error accumulation, and lighting-limited visual positioning. A key innovation is the integration of an extended Kalman filter (EKF) to dynamically fuse T265 visual odometry, inertial measurement unit (IMU), and GPS data, overcoming single-sensor limitations and enhancing positioning robustness in complex environments. Additionally, the study optimizes PID controller derivative parameters for tracked chassis, improving acceleration/deceleration control smoothness. The system, composed of Pixhawk 4, Raspberry Pi 4B, Silan S2L LIDAR, T265 visual odometry, and a Quectel EC200A 4G module, enables autonomous path planning, real-time obstacle avoidance, and multi-mission navigation. Indoor/outdoor tests and field experiments in Sun Village Orchard validated its autonomous cruising and obstacle avoidance capabilities under real-world orchard conditions, demonstrating feasibility for intelligent plant protection. Full article

The complexity and shortening of development cycles in the automotive industry, particularly with the rise in hybrid electric vehicle sales, increases the need for efficient calibration and testing methods. Virtualization using hardware-in-the-loop testbenches has the potential to counteract these trends, specifically for the calibration of hybrid operating strategies. This paper presents a dynamic closed-loop validation of a hardware-in-the-loop testbench designed for the virtual calibration of hybrid operating strategies for a plug-in hybrid electric vehicle. Requirements regarding the hardware-in-the-loop testbench accuracy are defined based on the investigated use case. From this, a dedicated hardware-in-the-loop testbench setup is derived, including an electrical setup as well as a plant simulation model. The model is then operated in a closed loop with a series production hybrid control unit. The closed-loop validation results demonstrate that the chassis simulation reproduces driving resistance closely aligning with the reference data. The driver model follows target speed profiles within acceptable limits, achieving an R² = 0.9993, comparable to the R² reached by trained human drivers. The transmission model replicates the gear ratios, maintaining rotational speed deviations below 30 min⁻¹. Furthermore, the shift strategy is implemented in a virtual control unit, resulting in a gear selection comparable to reference measurements. The energy flow simulation in the complete powertrain achieves high accuracy. Deviations in the high-voltage battery state of charge remain below 50 Wh in a WLTC charge-sustaining drive cycle and are thus within the acceptable error margin. The net energy change criterion is satisfied with the hardware-in-the-loop testbench, achieving a net energy change of 0.202%, closely matching the reference measurement of 0.159%. Maximum deviations in cumulative high-voltage battery energy are proven to be below 10% in both the charging and discharging directions. Fuel consumption and CO₂ emissions are modeled with deviations below 3%, validating the simulation’s representation of vehicle efficiency. Real-time capability is achieved under all investigated operating conditions and test scenarios. The testbench achieves a real-time factor of at least 1.104, ensuring execution within the hard real-time criterion. In conclusion, the closed-loop validation confirms that the developed hardware-in-the-loop testbench satisfies all predefined requirements, accurately simulating the behavior of the reference vehicle. Full article

Based on the current issues of difficulty in clearing intra-row weeds in orchards, inaccurate sensor detection, and the inability to adjust the row spacing depth, this study designs an intelligent intra-row obstacle avoidance and weeding machine for orchards. We designed the weeding machine’s sensor device, depth-limiting device, row spacing adjustment mechanism, joystick-based obstacle avoidance mechanism, weeding shovel, and hydraulic system. The sensor device integrates non-contact sensors and a mechanical tactile structure, which overcomes the instability of non-contact detection and avoids the risk of collision obstacle avoidance by the weeding parts. The weeding shovel can be adapted to the environments of orchards with small plant spacing. The combination of the sensor device and the obstacle avoidance mechanism realizes flexible obstacle avoidance. We used Ansys Workbench to conduct static and vibration modal analyses on the chassis of the in-field weeding machine. On this basis, through topology optimization, the chassis quality of the weeding machine is reduced by 8%, which realizes the goal of light weight and ensures the stable operation of the machinery. To further optimize the weeding operation parameters, we employed the Box–Behnken design response surface analysis, with weeding coverage as the optimization target. We systematically explored the effects of forward speed, hydraulic cylinder extension speed, and retraction speed on the weeding efficiency. The optimal operational parameter combination determined by this study for the weeding machine is as follows: forward speed of 0.5 m/s, hydraulic cylinder extension speed of 11.5 cm/s, and hydraulic cylinder retraction speed of 8 cm/s. Based on the theoretical analysis and scenario simulations, we validated the performance of the weeding machine through field experiments. The results show that the weeding machine, while exhibiting excellent obstacle avoidance performance, can achieve a maximum weeding coverage of 84.6%. This study provides a theoretical foundation and technical support for the design and development of in-field mechanical weeding, which is of great significance for achieving intelligent orchard management and further improving fruit yield and quality. Full article

Modern powertrain configurations for electric vehicles introduce the possibility to actuate the wheel directly by means of in-wheel motors. These machines enable stiffer and more efficient traction, with the possibility of introducing pitch motion control due to the intrinsic coupling between longitudinal, vertical, and pitch dynamics. This paper proposes a pitch rate attenuation control exploiting a Lyapunov function that attempts to cancel the pitch rate dynamics from the model. Unlike previous works, this pitch control is performed exclusively with the traction machine; it does not rely on controllable suspension systems. The controller formulation guarantees global stability of the vehicle. Furthermore, it considers the nonlinearity of the plant introduced by the dependency on the pitch angle. To facilitate the feedback of the road profile needed by the Lyapunov controller, two Kalman filters are included in the control law. This work implements the described strategy on a half car model. Simulations examine different speed and road conditions. It is demonstrated that the control strategy can blend longitudinal and pitch rate attenuation torque commands using a rear in-wheel motor, attaining a reduction of up to $41\%$ for chassis pitch rate and $36\%$ for pitch acceleration. Full article

With the advancement of modern agricultural technology, precision seeding has emerged as a critical approach to enhancing the crop yield and quality. Consequently, a garlic seeder insertion mechanism was developed to improve the accuracy and efficiency of garlic seeding. The single-seed extraction mechanism and the adjustment mechanism for the garlic clove direction were designed based on the appearance dimensions of garlic cloves, enabling precise single-seed selection and orientation. A kinematic model of the insertion planting process was established, with key parameters meticulously described and analyzed, providing theoretical support for determining optimal insertion parameters. A timing sequential control method was adopted to accurately control the periodic motion of the insertion planting mechanism. A speed detection device was utilized to monitor the travel speed of the crawler-type chassis and a rotational speed controller was developed to accurately regulate the rotational speed of the insertion mechanism, ensuring uniform planting distances. Field trials demonstrated that when the preset planting distance was set at 150 mm and sowing operations were conducted at speeds of 0.10 m/s, 0.15 m/s, and 0.20 m/s, the average sowing spacing values were 148 mm, 149 mm, and 151 mm, respectively, the maximum sowing spacing error and root mean square (RMS) error were 30 mm and 7 mm, with an average error of less than 10 mm, and the maximum coefficient of variation was 0.046. The upright rate exceeded 85%, and the missing seeding rate was below 5%. The above results indicated that the designed garlic planting machine insertion mechanism and control method conform to the agronomic requirements for garlic sowing operations. Full article

In view of the problems of low work efficiency and high operating costs caused by manual harvesting of Chinese cabbage in China, in this study, a Chinese cabbage harvester with agronomic integrity was designed. The harvester is mainly composed of a crawler chassis, a drawing device, a flexible clamping device, a cutting device, and a horizontal delivery device. Firstly, physical properties of Chinese cabbage such as diameter, plant height, weight, and drawing rate of Chinese cabbage were measured and analyzed to provide necessary basic data for the design of the harvester. Secondly, simulation tests were conducted on the Chinese cabbage harvesting process; a 3D model of Chinese cabbage using SolidWorks 2022 was established and filled with particles using the three-layer stacking method. At the same time, SolidWorks was applied to simplify the model of the Chinese cabbage harvester. The belt of the machine model was set as a flexible body through RecurDyn 2023 software and coupled with EDEM 2022 for simulation analysis. Based on single factor tests, the BBD model was applied to conduct multi-factor response surface analysis on the above factor levels. The optimal working conditions of the harvester were obtained as follows: the rotating speed of the cutting device was 207.85 r/min, the rotating speed of the flexible clamping conveyor belt was 165.51 r/min, the rotating speed of the drawing device was 102.38 r/min, and the machine walking speed was 1.37 km/h. The qualified rate of Chinese cabbage harvesting was the highest, achieving a maximum theoretical value of 97.91%. Field validation tests were conducted on the designed Chinese cabbage harvester. Based on the actual operating conditions of the Chinese cabbage harvester and the simulated operating parameters, the optimal parameter combination was finally determined as follows: rotating speed of the root cutting device was 200 r/min, rotating speed of the flexible clamping conveyor belt was 160 r/min, rotating speed of the drawing device was 100 r/min, and machine walking speed was 1.4 km/h, respectively. Through field verification tests, the highest qualified rate of Chinese cabbage harvesting reached 93.19%, showing a good harvesting effect, which approximates the simulated optimal qualified rate of 97.91%, meeting the mechanized harvesting demand of Chinese cabbage. This study provides reference to the further design and development of Chinese cabbage harvesters in the future. Full article

Based on the characteristics of small agricultural machinery in terms of flexibility and high efficiency when operating in small plots of hilly and mountainous areas, as well as the demand for improving the automation and intelligence levels of agricultural machinery, this paper conducted research on the path tracking control of the automatic navigation operation of a crawler sprayer. Based on the principles of the kinematic model and the position prediction model of the agricultural machinery chassis, a pure pursuit controller based on adaptive look-ahead distance was designed for the tracked motion chassis. Using a lightweight crawler sprayer as the research platform, integrating onboard industrial control computers, sensors, communication modules, and other hardware, an automatic navigation operation system was constructed, achieving precise control of the crawler sprayer during the path tracking process. Simulation test results show that the path tracking control method based on adaptive look-ahead distance has the characteristics of smooth control and small steady-state error. Field tests indicate that the crawler sprayer exhibits small deviations during path tracking, with an average absolute error of 2.15 cm and a maximum deviation of 4.08 cm when operating at a speed of 0.7 m/s. In the line-following test, with initial position deviations of 0.5 m, 1.0 m, and 1.5 m, the line-following times were 7.45 s, 11.91 s, and 13.66 s, respectively, and the line-following distances were 5.21 m, 8.34 m, and 9.56 m, respectively. The maximum overshoot values were 6.4%, 10.5%, and 12.6%, respectively. The autonomous navigation experiments showed a maximum deviation of 5.78 cm and a mean absolute error of 2.69 cm. The proportion of path deviations within ±5 cm and ±10 cm was 97.32% and 100%, respectively, confirming the feasibility of the proposed path tracking control method. This significantly enhanced the path tracking performance of the crawler sprayer while meeting the requirements for autonomous plant protection spraying operations. Full article

Chaetoglobosin A (CheA), a typical structure of the cytochalasin family, exhibits outstanding efficacy against a variety of tumor cells and plant pathogens. However, its low yield and high production cost are major obstacles limiting its wide application. In order to increase CheA yield, an engineered strain was established by overexpressing CgMfs, the gene encoding the MFS family’s efflux pump, on chassis cells lacking CgXpp1, which have been shown to act as a negative regulator of CheA biosynthesis. As expected, the engineered strain significantly boosted CheA production from 63.19 to 265.93 mg/L after incubation in PDA medium for 10 d, whereas the yield of the engineered strain was remarkably enhanced 2.93-fold compared with the wild type, following 10 d of cultivation utilizing potato starch industrial waste. The addition of metal ions had a positive effect on CheA production, with Cu²⁺ being the most effective and improving production to 176.92 mg/L. The optimal fermentation conditions were determined by response surface optimization, and under the optimal conditions, the engineered strain could stably produce CheA with a yield of 197.58 mg/L. This study provided the conditions for reducing production costs while increasing CheA production, as well as new strategies and insights for the production of the target compound. Full article

Dendrobine, a significant medicinal compound, typically accumulates at low concentrations within several Dendrobium species, including Dendrobium nobile, Dendrobium catenatum, and Dendrobium moniliforme. As D. nobile and D. catenatum are established ingredients in traditional Chinese medicine and have been cultivated extensively, they present ideal plant chassis for upscaling dendrobine production for industrial and research applications. This study employed two approaches: the ectopic overexpression of seven genes through multigene stacking and the activation of multiple key endogenous genes in the dendrobine synthesis pathway using CRISPR/Act3.0 in either D. nobile or D. catenatum. These methods enhanced dendrobine production in transiently infiltrated leaves by 30.1% and transgenic plants by 35.6%. The study is the first to apply CRISPR/Act3.0 to Dendrobium orchids, enhancing dendrobine production, and thus laying a solid foundation for further improvements. CRISPR/Act3.0 is a recently developed technique that demonstrates high efficiency in model plant species, including rice, maize, and Arabidopsis. By combining CRISPR with transcriptional regulatory modules, activation of multiple endogenous genes in the metabolic pathway can be achieved. The successful application in orchid molecular breeding reveals promising potential for further exploration. Full article

To address the lack of mechanical orchard operation-aid platforms that assist in the horticultural management tasks such as pruning, spraying, thinning flowers and fruits, and harvesting in litchi and longan orchards, this paper proposes an orchard operation-aid platform specifically tailored for hilly and mountainous orchards. The platform is optimized for orchards with tree and row spacing not exceeding 6 m and slopes not exceeding 15°. By considering the planting patterns and operational topography parameters of litchi and longan, the key components were meticulously designed, including the chassis, lifting device, extension device, and slope operation support device. The driving stability, slope operation stability, and the reachable workspace of the orchard operation-aid platform were analyzed, followed by a prototype experiment. The results demonstrate that the platform achieves an in situ turning radius of 1.2 m with no deviation in the turning path. It satisfies the passability and operational slope requirements of hilly terrains with both driving and operational slopes exceeding 15°. Additionally, the platform features a working height of 4.0 m and an operating radius of 3.7 m, meeting the operational requirements for multiple tasks. This research provides a practical and effective solution for enhancing operational efficiency in multiple stages of fruit cultivation, demonstrating significant practical value and potential for widespread application. Full article