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Abstract For citrus trees cultivated by dwarf dense planting, the fruits are randomly distributed in space, which poses difficulties for mechanized picking. To improve picking efficiency, a citrus picking system based on dual robot collaboration is designed and a global scanning picking scheme that scans the entire fruit tree to achieve orderly fruit picking is proposed in this research. The dual‐robot calibration with the iterative method and closed‐form method is completed in the research. The picking problem is attributed to the single traveling salesman problem, and the trajectory planning and the picking task are completed with genetic algorithm in the research. The picking experiments are designed in the research. As a result, in the picking experiments, the average time for planning the picking sequence of citrus was 0.1184 s, the longest time is 0.1560 s. In each group of citrus picking experiments, the total picking time averaged 158.9 s, the longest group took 170 s, the picking success rate is 82%. The picking results show that the built dual‐machine system can effectively complete the picking task and meet the real‐time requirement of picking. The proposed dual‐robot picking system can provide a reference for the establishment of other picking robot system.

Boron (B) is essential for plant growth, but toxic in excess. In several countries, soil toxic B levels are always a severe agricultural problem in arid and semi-arid regions. Phytoremediation of excess B containing soil is still in its infancy, while high B tolerant plants with elevated protein abundance of B efflux transporter were successfully established or explored. Brassica napus (B. napus) is one of the most important oil crops. However, B efflux transporters underlying excess B tolerance in B. napus remain unknown. Here, we reported that in Brassicaceae species, B. napus had four homologous genes of Arabidopsis AtBOR4 , which were renamed BnaBOR4.1, BnaBOR4.2, BnaBOR4.3 and BnaBOR4.4. BnaBOR4.1, BnaBOR4.2 and BnaBOR4.3 showed constitutive expression and BnaBOR4.4 appeared to be a pseudogene. BnaBOR4.2 and BnaBOR4.3 were expressed in inner cell layers and BnaBOR4.1 in the outer cell layer in root tip, and all were expressed in vascular tissue in the mature zone. B efflux activity assays in yeast demonstrated that BnaBOR4.1, BnaBOR4.2 and AtBOR4 but not BnaBOR4.3 had comparable levels of B transport activity. Structure-functional analysis between BnaBOR4.3 and BnaBOR4.2 demonstrated that amino acid residue substitution at position 297 (Ala vs Pro) and 427 (Met vs Leu) is critical for the B transport activity. Mutant BnaBOR4.3M427L partially restored the B efflux activity, and both mutants BnaBOR4.3A297P and BnaBOR4.3A297P&M427L fully restored B efflux activity, indicating that the Pro297 residue is critical for their function. Further validation of BnaBOR4 was accomplished by growing transgenic Arabidopsis plants under high B conditions. Taken together, our study identified two functional B efflux genes BnaBOR4.1 and BnaBOR4.2 in B. napus, and a key amino acid residue proline 297 associated with B efflux activity. This study highlights the potential of BanBOR4 genes for B. napus cultivation under high B stress.

An automatic feeding device for substrate filling was designed to address the challenges of difficult feeding and low efficiency in the citrus seedling pot filling and transferring machine. The device comprises a framework, tracks, overturning frame, drive system, etc. In order to ensure optimal performance, the frame’s turning angle was set at a minimum of 110° and the angle between the frame’s horizontal plane and slope was determined to be 120°. Following optimization, the number and intensity of sudden changes in velocity, angular velocity, and thrust were reduced, thereby prolonging the device’s service life. The prototype test demonstrated that the device has an average feeding time of 9.86 s, is capable of raising 0.14 m3 of substrate in a single cycle, and has a handcart turning angle of 111°. Furthermore, no residual substrate remained in the handcart, and the handcart fixing mechanism operated correctly. The torque measurement results of the motor output shaft were found to be consistent with the simulation results in ADAMS, with a maximum force difference of only 298 N. The simulation was found to be accurate, with an error rate of only 3.67%. This model can be utilized as a dependable reference for the optimization of the design of the automatic feeding device.

Abstract To solve the problems of agricultural machinery simplification, lack of universality and uneven land in mountain orchards, a light self‐propelled universal mobile platform for mountain orchards is studied in this paper. A light crawler chassis, an electric drive system and a multi‐sensor control system are designed. Through the kinematics and dynamics modelling of the general platform, the prediction model of the motion system of the general mobile platform is determined. Then the observation model of the system motion is determined based on the multi‐sensor fusion, and the multi‐sensor fusion navigation control system is established. Based on the energy consumption model of mobile platform, the energy consumption optimal trajectory planning is carried out. The energy consumption optimal trajectory radius is 2.5 m and the deflection angle is 36.9°, and the optimal trajectory radius of energy consumption is 1.9 m. Orchard experiments show that the maximum lateral displacement deviation of the universal mobile platform is less than 0.1 m, which can basically achieve the expected trajectory autonomous walking function.

Multi-robot systems can perform more complex tasks with high precision and large loads than single-robot systems. The calibration of the base coordinate system is the basis and premise to ensure the collaborative operation between the dual-robot. In this study, a dual-robot calibration system based on calibration tooling components was established, which could quickly and accurately obtain the relative position between dual robots. Based on three reference measurement points of the orthogonal distribution in the calibration tool coordinate system, a mapping relationship between the distance from the reference measurement point to the robot end point and the parameters of the robot base system was established, and a fast dual-robot base system parameter calibration solution method based on "three-point measurement calibration" was proposed. The experimental results show that this method can quickly and accurately obtain the transformation relationship between the dual robot base coordinate systems. The accuracy and efficiency of the calibration have been greatly improved. It is of great significance for meeting the requirements of high efficiency, low cost, and easy operation in the factory application process.

Walnut shell breaking is the first step of deep walnut processing. This study aims to investigate the mechanical properties and fracture state of the Qingxiang walnut shell under unidirectional load and guide the complete separation of the walnut shell and kernel. The spherical thin shell model of the walnut (the fitting error is less than 5%) was established and verified. The process from the initiation to the expansion of walnut cracks was analyzed. The crack expansion rate was estimated in terms of the crack fracture regularity on the shell’s surface. Based on the momentless theory and finite element simulation analysis, we found that the stress on the shell surface in the concentrated force action region was gradient distributed from inside to outside and that the internal forces were equal in all directions in the peripheral force action region. The unidirectional impact shell-breaking experiments confirmed the reliability of our spherical thin shell model and verified our hypothesis of walnut shell fracture along the longitudinal grain. Our results can provide a theoretical basis for the development and structural optimization of shell-breaking machinery.

In Southeast Asia, many varieties of citrus are grown in hilly areas. Compared with plain orchards, it is difficult for large spraying equipment to move in hilly orchards. Small spraying equipment can enter hilly orchards, but their spraying power cannot make droplets penetrate into the canopy, resulting in low deposition rates within the canopy. As a kind of unstructured narrow space, the branches within the canopy are interlaced, thus a flexible manipulator that can move within the canopy is required. In this paper, a novel remote-controlled, cable-driven target spray robot (CDTSR) was designed to achieve a precise spray within the canopy. It consisted of a small tracked vehicle, a cable-driven flexible manipulator (CDFM), and a spray system. The CDFM had six degrees of freedom driven by a cable tendon. The forward and inverse kinematics model of the CDFM were established and then the semispherical workspace was calculated. Furthermore, while considering precise control requirements, the dynamics equations were derived. The experimental results demonstrated that the CFDM could move dexterously within the canopy with interlacing branches to reach pests and diseases areas in the canopy. The entire operation took 3.5 s. This study solved the problem of a low spray deposition rate within a canopy and has potential applications in agricultural plant protection.

Nuts are the important economic forest tree species of China. De-shell is the key operation of nut deep processing. There are some problems in the current nut cracking devices such as the low decorticating rate, the high nuts losses rate and nutmeat integrity problems, etc.. The foundation of force analysis is to establish contact model for nut and mechanical. The nut surface is rough and irregular, so the contact area cannot be modeled as regular shape. How to set up contact constraint model is the key problem to accomplish non-loss shelling. In order to study the shell-breaking mechanism and structural design of the nut shelling manipulation, a multi-fingered metamorphic manipulator is presented. An overview of the nut shelling technology and the contact manipulator modeling are proposed. The origin and application of metamorphic mechanisms are introduced. Then the research contents and development prospects of nut shelling manipulator are described.

Air bearings have been widely used in ultra-precision positioning stages due to the property of nearly zero friction or wear. Small vibration of the bearing reduces the overall moving and positioning precision of the stage and hampers its applications in fabrication facilities requiring nanometer moving and positioning precision. In order to improve system precision, knowledge of the dynamic characteristics of air bearings is the first and crucial step. However, it is still a challenge to set up an accurate dynamic model for air bearings due to the system complexity. In this article, a novel method for the dynamic modeling of air bearing is proposed, which takes into account the dynamics in both the moving direction and the supporting direction. An ultra-precision positioning dual stage is investigated using the proposed dynamic modeling method. This stage has two sets of air bearings and can be used in integrated circuit fabrication equipments. Moreover, dynamic behaviors of the ultra-precision positioning dual stage are studied and compared with experimental results to validate the effectiveness and accuracy of the proposed method.

The structural flexibility, nonlinear friction, and backlash are the major factors limiting the control performance of precision transmission systems. If uncompensated, these factors compromise the positioning and tracking accuracy of precision transmission systems and even cause limit cycles and oscillation. In this article, a framework for integrated design from dynamic modeling to controller design is proposed. A multi-state dynamic model is presented, which can unify the modeling for a multi-state, discontinuous system including the motor state, the motion state, the mechanical contact state, and the friction state. Then, a control design method related to the dynamic modeling using perturbation separation of the model parameters is presented. Using the proposed modeling method, a continuous dynamic model is established to include all different partition models. The model comprehensively describes the mechanical and electrical characteristics of the precision transmission system. A robust controller is designed using the proposed control method. Experimental results demonstrate that the proposed modeling method is accurate and the proposed control method significantly improves accuracy and robustness of the controller compared to traditional control methods.

The precise and automatic cutting of sheep carcasses can improve the quality of mutton. Robots are widely used in meat processing because of their good repeatability and high precision. Two essential problems encountered in robot working of sheep carcass processing are robot calibration and cutting trajectory planning. A method of cutting sheep carcasses based on 3D point clouds with a dual-robot system was proposed in this study. The dual-robot system consists of a 3D scanning system, a fixing device for sheep carcasses, and a cutting robot. The calibration of the dual-robot system was completed by solving the matrix problem AXB=YCZ using the iterative method and the closed-form method. The 3D model of a sheep carcass was constructed using a 3D scanner. The cutting scheme of the cutting robot was planned based on the processed 3D point clouds. To show the feasibility of the proposed sheep carcass processing scheme, practical experiments were carried out. The results of the experiments show that the cutting robot can accurately perform the cutting actions according to the planned cutting scheme. The system proposed in this study can improve the efficiency and precision of sheep carcass cutting. [ABSTRACT FROM AUTHOR]

In order to study the influence rule of various factors on the operation power consumption of the traction orchard transporter and realize the optimal design of the operation power consumption of the transporter, according to the traditional experience and the existing research foundation, the monorail transporter test bench was designed and built on the basis of the whole structure and operation characteristics of the transporter. Taking the motor frequency, track gradient and load as the investigation factors, and the driving shaft power, shaft power transmission and mechanical efficiency as the evaluation indices, the orthogonal test was conducted, and the range analysis of the influence effect was carried out according to the test results. The primary and secondary orders of the influence of various factors were obtained that motor frequency was greater than track gradient and track gradient was greater than load. According to the orthogonal test results, the second-order response surface method was used to establish the optimization model of the power consumption of the transporter, and the model was verified on the test bench. The results showed that the relative error between the model optimization value and the test value based on the response surface power optimization model was less than 10%, which indicated that the power optimization model had satisfactory performance. The research can provide a reference for the orchard conveyor to choose the parameter combination which can save power consumption and the motor that matches power consumption [ABSTRACT FROM AUTHOR]