Automatic Scallion Seedling Feeding Mechanism with an Asymmetrical High-order Transmission Gear Train

The current automatic scallion-transplanting machine is a complicated mechanism composed of two linkage mechanisms and two band carriers.It delivers seedlings ine ciently because of the movement limitations of the linkage mechanism.This paper proposes a new high-order non-circular gear train for an automatic scallion-seedling feeding mechanism.The proposed gear train has an asymmetrical transmission ratio;i.e.,its transmission ratio varies.This allows the mechanism’s execution component to move in a long displacement and rotate in a large rotation angle.The long displacement enables the execution component to reach the designed working position,and the large rotation angle allows it to feed a scallion in the required pose.A mathematical model for calculating the asymmetrical transmission ratio was established according to the closure requirements and the full-cycle motion of the driven gear pitch curve.Then,the parameter-design model of the new seedling-feeding mechanism was established,based on precise pose points and trajectory-shape control points.Moreover,an aided-design program was developed to obtain the parameter-solution domain of the scallion-seedling feeding mechanism.The mechanism parameters,which met the seedling-feeding function,were optimized to determine the transmission ratio,using a program and a kinematic simulation.Finally,a prototype of the mechanism was produced,and a seedling-feeding experiment was carried out.One-thousand seedlings were tested at a rate of 100 seedlings per minute,and the statistical success rate was 93.4%.Thus,the automatic scallion-seedling feeding mechanism significantly improves the e ciency of automatically transplanting scallions.

Locating Famous Tea’s Picking Point Based on Shi-Tomasi Algorithm

To address the difficulty of locating the picking point of a tea sprout during the intelligent automatic picking of famous tea,this study proposes a method to obtain information on the picking point on the basis of the ShiTomasi algorithm.This method can rapidly identify a tea sprout’s picking point and obtain its coordinates.Images of tea sprouts in a tea garden were collected,and the G-B component of tea sprouts was segmented using the Otsu algorithm.The region of interest was set with the lowest point of its contour as the center.The characteristics of tea buds and branches in the area were extracted,and the Otsu algorithm was used for a second segmentation of tea sprout images.The tea buds were segmented using the improved Zhang algorithm.The branch feature binary image was used to refine the skeleton,and the Shi-Tomasi algorithm was used to detect the corners of the skeleton and calculate and mark the picking points of the shoots.Sixty sets of samples were tested.The test identified 1,042 effective shoots for tender buds,and 887 picking points were marked,with a success rate of 85.12%,thereby verifying the effectiveness of the method and providing a theoretical reference for the visual positioning of the automatic picking of famous tea.

Research and Test of Three-Pulley Noncircular Synchronous Pulley Transmission Mechanism with Minimum Slack

The noncircular synchronous belt drive mechanism has demonstrated certain achievements and has been used in special fields.Research regarding noncircular synchronous belt drive mechanisms has focused on optimization design and kinematic analysis in China,whereas two pulley noncircular synchronous belt transmissions have been developed overseas.However,owing to the noncircular characteristics of the belt pulley,the real-time variation in the belt length slack during the transmission of the noncircular synchronous belt is significant,resulting in high probabilities of skipping and vibration.In this study,a noncircular tensioning pulley is added to create a stable three-pulley noncircular synchronous belt driving mechanism and a good synchronous belt tensioning,with no skipping;hence,the non-uniform output characteristic of the driven pulley is consistent with the theoretical value.In the circular noncircular noncircular three-pulley noncircular synchronous belt mechanism,the pitch curve of the driving synchronous belt pulley is circular,whereas those of the driven synchronous belt and tensioning pulleys are noncircular.To minimize the slack of the belt length of the synchronous belt and the constraint of the concavity and circumference of the tensioning pulley,an automatic optimization model of the tensioning pulley pitch curve is established.The motion simulation,analysis,and optimization code for a three-belt-pulley noncircular synchronous belt drive mechanism is written,and the variation in belt length slack under different speed ratios is analyzed based on several examples.The testbed for a circular-noncircular-noncircular three-pulley noncircular synchronous belt transmission mechanism is developed.The test shows that the three-pulley noncircular synchronous belt drives well.This study proposes an automatic optimization algorithm for the tensioning pulley pitch curve of a noncircular synchronous belt transmission mechanism;it yields a stable transmission of the noncircular synchronous belt transmission mechanism as well as non-uniform output characteristics.

Optimization design and experiment of the variable differential gear train planting mechanism

In order to improve the adaptability of the planting mechanism for different plant spacings,a variable differential gear train planting mechanism based on precise pose and trajectory control was proposed by combining the open chain 2R rod group and the variable differential gear train.According to the pose requirements of receiving seedling point,transporting seedling point and planting point,three precise pose points of constrained planting trajectory were determined.Through the three-position motion generation structural synthesis method,combined with computer-aided optimization design software,a set of mechanism parameters that meet the planting requirements were optimized.Based on the optimized mechanism parameters,by only changing the coordinates of two trajectory shape control points,three planting trajectories with key point position information adapted to 300 mm,400 mm and 500 mm plant spacing were obtained by interpolation,and three pairs of total transmission ratio of three groups of variable differential gear trains were calculated.When distributing the total transmission ratio of the mechanism,the fixed axis gear train and the differential gear train are combined.The fixed axis gear train included a pair of non-circular gear pairs and a pair of positive gear pairs,which were convenient for disassembly and assembly.The former drives the sun gear at variable speed,and the latter drives the planet carrier at uniform speed.Based on this structure,the transmission ratio of the positive gear pair is-1,and the transmission ratio of the differential gear train is 0.5.The sub-transmission ratio of the single-stage non-circular gear pair was calculated and the pitch curves of three pairs of noncircular gears were solved.Three pairs of non-circular gear pairs with different transmission ratios were replaced in turn and three sets of planting mechanisms were modeled in three dimensions.The virtual prototype motion simulation was completed by ADAMS software,and the physical prototype was built for vegetable pot seedling planting test.The theoretical solution was consistent with the attitude and trajectory of the actual test.When the test sample size was 100 plants,the actual average plant spacing was measured to be 303 mm,402 mm,and 503 mm,with errors of 1.3%,1.25%,and 1.88%.The width of the moving hole was 72 mm,70 mm,and 71 mm,and the planting success rate were 94%,96%,and 95%.The test results verified the correctness of the optimization design results of the mechanism,indicating that the variable differential gear train planting mechanism can adapt to a variety of plant spacing and has good planting effect.

DMT:A model detecting multispecies of tea buds in multi-seasons

In China,tea products made from fresh leaves characterized by one leaf with one bud(1L1B)are classified as“Famous Tea”,which has better taste and higher economic value,but suffers from a labor shortage.Aiming at picking automation,existing studies focus on visual detection of 1L1B,but algorithm validation is limited to a specific variety of tea sprouting in a certain harvest season at a certain location,which limits the engineering application of developed tea picking robots working in various natural tea fields.To address this gap,a deep learning model DMT(detecting multispecies of tea)based on YOLOX-S was proposed in this paper.The DMT network takes YOLOX-S as a baseline and adds ECA-Net to the CSP Darknet and FPN of YOLOX-S.The average precision(AP),precision,and recall of DMT are 94.23%,93.39%,and 88.02%,respectively,for detecting 1L1B sprouting in spring;93.92%,93.56%,and 87.88%,respectively,for detecting 1L1Bsprouting in autumn.These experimental results are better than those of the five current object detection models.After fine-tuning the DMT network with another dataset composed of multiple tea varieties,the DMT network can detect 1L1B for different varieties of tea in multiple picking seasons.The results can promote the engineering application of picking automation of fresh tea leaves.

Development and experiment of the mechanism for oolong tea stirring motion based on the manual stirring characteristics analysis

In this study,the motion characteristics of manual stirring were analyzed to achieve the goal of realizing a highquality mechanized imitation of manual stirring for oolong tea.A test bench for collecting the motion characteristics of manual stirring was designed,and the standard manual stirring motion characteristic curve was obtained.According to the requirements of the stirring motion characteristics,a variable-speed and variable-amplitude stirring mechanism was proposed,the kinematics model and reverse design model of the stirring mechanism were established,auxiliary analysis and design software were written,and the non-circular gear pitch curve and cam profile curve were obtained.A three-dimensional model of the stirring machine was established,a virtual prototype of the stirring machine was built,and the simulation experiment was completed by using the ADAMS software.A prototype of the stirring machine was developed,and the stirring experiment was conducted on the prototype.The maximum deviation of the pitch angle is 2.8772°,and the maximum deviation of the roll angle is 1.5948°according to the analysis and comparison of the actual curve data and the theoretical data curve.The experimental results showed that the simulation angle curve and the actual angle curve were consistent with the theoretical standard manual stirring motion characteristic curve,which verified the correctness of the design and modeling of the stirring mechanism.The tea was mechanically stirred by the stirring mechanism to achieve the desired stirring effect,which verified the feasibility of the stirring machine.

Research and experiment of a novel flower transplanting device using hybrid-driven mechanism

Aiming at decreasing the component complexity and cost of flower transplanting machine,an integrated transplanting method for picking and planting flower seedlings was proposed,and a hybrid-driven five-bar parallel mechanism was designed.A“beak-shaped”trajectory was designed for integrated transplanting requirements,and meantime,either the posture requirements of transplanting claw were determined.Based on the transplanting trajectory of the mechanism,a corresponding mathematical model for solving the link parameters was established,and then the five-bar mechanism was divided into two bar groups,optimization was conducted in two steps based on genetic algorithm and NSGA-II algorithm.Consequently,the optimal solution of the hybrid-driven five-bar parallel mechanism for flower seedling transplanting was obtained.Compared with similar designs,the trajectory displacement of the proposed mechanism is larger in the condition of smaller link size,which indicates that the mechanism can effectively decrease the machine size.The real-time controllable motor angular acceleration fluctuation is smaller and the commutation times are less,which has the advantage of reducing the difficulty of the mechanism control system.Subsequently,the correctness of the design method is verified by kinematics simulation.Finally,the synchronous linkage motion control methods of the two motors were designed,a transplanting experiment of the prototype was carried out,the picking success rate had reached 90%-93.4%and transplanting success rate was 80.5%-86.9%during experiment,which showed that the integrated operation of picking and planting flower seedlings can be realized by the proposed mechanism.

High-efficiency tea shoot detection method via a compressed deep learning model

Achieving high-efficiency and accurate detection of tea shoots in fields are essential for tea robotic plucking. A real-time tea shoot detection method using the channel and layer pruned YOLOv3-SPP deep learning algorithm was proposed in this study. First, tea shoot images were collected and data augmentation was performed to increase sample diversity, and then a spatial pyramid pooling module was added to the YOLOv3 model to detect tea shoots. To simplify the tea shoot detection model and improve the detection speed, the channel pruning algorithm and layer pruning algorithm were used to compress the model. Finally, the model was fine-tuned to restore its accuracy, and achieve the fast and accurate detection of tea shoots. The test results demonstrated that the number of parameters, model size, and inference time of the tea shoot detection model after compression reduced by 96.82%, 96.81%, and 59.62%, respectively, whereas the mean average precision of the model was only 0.40% lower than that of the original model. In the field test, the compressed model was deployed on a Jetson Xavier NX to conduct the detection of tea shoots. The experimental results demonstrated that the detection speed of the compressed model was 15.9 fps, which was 3.18 times that of the original model. All the results indicate that the proposed method could be deployed on tea harvesting robots with low computing power to achieve high efficiency and accurate detection.

Design of flower transplanting mechanisms based on double planet carrier non-circular gear train with complete rotation kinematic pair

In view of the problems of the existing mechanisms based on 2R open-chain planetary gear train for seedling transplanting,such as the bad tracking flexibility,low positioning accuracy,and high structure design difficulties of the mechanisms based on 3R open-chain planetary gear train for seedling manipulation.In this paper,a transplanting mechanism based on the solution domain synthesis of a 3R open-chain-based complete rotation kinematic pair,a gear train with a single cycle integral rotating pair,is designed.The Burmester curve equation is derived from the given transplanting trajectory and four exact poses corresponding to each other on the rotation center.Then,the open-chain road model of the 3R complete rotation kinematic pair is obtained under the constraint governed by the judgment condition of the hinge integral rotating pair.Meanwhile,combined with our developed in-house optimization software,the solution to the optimal parameters for the transplanting mechanism can be optimized according to the target trajectory.Finally,the feasibility of the design method is verified by transplanting testing,where kale seedlings with ages of about 20 d and heights of about 80-120 mm are used.The experimental results show that the actual motion trajectory of the prototype is basically identical to the theoretical trajectory,validating the feasibility of transplanting mechanism design,parts processing,and test-bed construction.Through the statistical analysis,the average success rate of transplanting is 90.625%,and the reliability of designed mechanism is satisfied.This study provides a promising solution for the seedling transplanting of two-planet scaffold pots.

Design and experiment of double planet carrier planetary gear flower transplanting mechanism

At present,there is a lack of miniaturized and highly reliable plug seedling transplanting mechanism in flowerpots planting operation,in order to meet the needs of large displacement and high vertical uprightness for flower transplanting,the paper combined the transmission characteristics of the non-circular gear planetary gear train with the swing flexibility of the cam gear and proposed a double planet carrier planetary gear transplanting mechanism.The linkage of the mechanism performs variable speed rotation relative to the first planet carrier,the linkage serves as the second planet carrier,and the transplanting arm performs variable speed swing relative to the linkage.A mathematical model of a single planetary carrier mechanism was first established using the method of open linkage group solution domain synthesis,then established the kinematic equations of the second planet carrier and the transplanting arm.The two parts are combined to form the mathematical solution model of the proposed mechanism.The initial trajectory was planned according to the trajectory requirements of seedlings planting operation,the non-circular gear pitch curve in the first planet carrier was obtained and the length of the first planet carrier is 120 mm.Then using the key points’angular deviation between the initial trajectory and the improved trajectory to obtain the cam parameters which driving the transplant arm,consequently determined the length of the second planet carrier is 69.25 mm and the length of the transplant arm is 112.4 mm.Finally,the prototype of the mechanism was manufactured,and the test verified the correctness of the design method of the double planet carrier planetary gear flower potting transplanting mechanism.The transplanting success rate of this mechanism reached 94.43%,and the plug seedlings planted in flowerpots had high uprightness.This research can provide a reference for the automatic development of research on flower transplanting machines.