Automatic Transplanting Research Articles

Design and Testing of a Seedling Pick-Up Device for a Facility Tomato Automatic Transplanting Machine.

At present, tomato transplanting in facility agriculture is mainly manual operation. In an attempt to resolve the problems of high labor intensity and low efficiency of manual operation, this paper designs a clip stem automatic transplanting and seedling picking device based on the yolov5 algorithm. First of all, through the study of the characteristics of tomato seedlings of different seedling ages, the age of tomato seedlings suitable for transplanting was obtained. Secondly, the improved yolov5 algorithm was used to determine the position and shape of tomato seedlings. By adding a lightweight upsampling operator (CARAFE) and an improved loss function, the feature extraction ability and detection speed of tomato seedling stems were improved. The accuracy of the improved yolov5 algorithm reached 92.6%, and mAP_0.5 reached 95.4%. Finally, the seedling verification test was carried out with tomato seedlings of about 40 days old. The test results show that the damage rate of the device is 7.2%, and the success rate is not less than 90.3%. This study can provide a reference for research into automatic transplanting machines.

Design and Test of Seedling-Picking Mechanism of Fully Automatic Transplanting Machine

The seedling retrieval mechanism is a crucial component of fully automatic transplanting machines, significantly influencing the quality, reliability, and efficiency of the transplanting process. Nonetheless, the existing seedling retrieval mechanisms in current transplanting machines exhibit several deficiencies, including substantial damage to seedlings and inadequate retrieval accuracy. To overcome these challenges, we propose an integrated approach combining pneumatic and mechanical techniques to further improve performance. By employing a lower thimble elevation and clamping mechanism, alongside a mathematical model based on the seedling removal process, this method ensures precise seedling extraction and minimizes damage to the root system and substrate. The novelty of this study lies in its ability to reduce the adhesion between seedlings and the holes of the plug plate, thereby minimizing non-destructive extraction of the seedlings and preserving the integrity of the matrix, which is essential for ensuring healthy seedling growth. Moreover, the optimization of the seedling retrieval trajectory enhances the accuracy of the seedling retrieval mechanism while also meeting the requisite speed requirements. Experimental results indicate that at a rate of 72 seedlings per minute, the extraction success rate reached 94.90%, and the casting success rate was 98.53%. The seedling injury rate was only 1.95%, resulting in an overall success rate of 91.69%. These findings confirm that the device meets operational efficiency requirements and delivers effective performance.

Precise Servo-Control System of a Dual-Axis Positioning Tray Conveying Device for Automatic Transplanting Machine

Precise Servo-Control System of a Dual-Axis Positioning Tray Conveying Device for Automatic Transplanting Machine

Design and Experiment of Planting Mechanism of Automatic Transplanter for Densely Planted Vegetables

The planting mechanism of existing transplanters cannot meet the agronomic requirements of planting densely planted vegetables with multiple rows, small plant spacing, and small row spacing. In order to solve this current problem, an eight-row duckbill planting mechanism driven by a motor and a cylinder was designed. According to the agronomic guidance and mechanism design requirements for transplanting densely planted vegetable seedlings, this paper analyzes the working principle of the planting mechanism, establishes its kinematic theoretical model, and determines the structural parameters of the driving device and opening and closing device in the planting mechanism. Aimed at the problem of large planting resistance when eight-row planting end effectors of the planting mechanism are planting at the same time, based on the existing research, three duckbill planting end effectors with double incisions, four incisions, and conical structures were selected, and the planting process was simulated using an EDEM 2022-RecurDyn 2024 coupling simulation. The single-factor analysis method and the interactive factor Box–Behnken response surface analysis method were used. It is concluded that the duckbill end effector with double incisions has the smallest planting resistance, and the rationality of the mechanism design is preliminarily verified. A planting resistance measurement platform was built based on the STM32 platform and HX711 module, and a planting resistance test of the duckbill planting end effector was carried out to verify the correctness of the planting mechanism simulation results. The planting mechanism performance test was carried out, and the test results showed that the planting qualification rate of the prototype reached 96.62%, the planting spacing variation coefficient was only 3.55%, and the planting efficiency reached about 7135 plants/h, which met the agronomic requirements of small plant spacing and small row spacing for densely planted vegetables and verified the feasibility and practicality of the planting mechanism.

Design and Experimental Study of a Traction Double-Row Automatic Transplanter for Solanum Lycopersicum Seedlings

The most important part of fruit cultivation is transplanting, which can be completed efficiently by an automatic transplanter. In this study, an automatic solanum lycopersicum transplanter was developed. It is primarily composed of the following devices: a seedling tray fixator, a mechanical transplanting arm, double horizontal driving modules, double vertical driving cylinders, a seedling separation device, double-crank five-bar planting devices, a power distribution system, and a PLC control system. An experimental test on an automatic transplanter was carried out on dry land. The experimental results showed that when the planting frequency was 80 plants/(min·row), the transplanting success rate was 93.89%, the missed planting rate was 1.58%, the replanting rate was 0.65%, the lodging rate was 1.94%, and the exposed seedling rate was 1.94%. Each device of the automatic transplanter was coordinated to complete the transplanting process. The automatic transplanter met the operation requirements, and it not only transplanted in dry land but also provided a theoretical basis for fruit cultivation in solar greenhouses in the future.

Design and Experiment of Dual-Row Seedling Pick-Up Device for High-Speed Automatic Transplanting Machine

To address the inefficiency and instability of automatic transplanting machines, a dual-row seedling pick-up device and its corresponding control system were developed. Existing seedling end-effectors are primarily mechanically controlled, and the seedling needles can easily cause damage to the interior of the bowl. In order to reduce the damage inflicted by the end-effectors to the bowl, this paper conducted a mechanical analysis of the end-effector. At the same time, a buffer optimization analysis was conducted on the operation of the end-effector, and a flexible pneumatic end-effector for seedling picking was designed. The control system combined the detection of multiple sensors to monitor the process of seedling picking and throwing. By coordinating the lifting cylinder and clamping cylinder, the system effectively reduced seedling pot damage while improving seedling picking efficiency. By setting the operating parameters of the servo motor, the goal of low-speed and high-efficiency seedling picking was achieved. To evaluate the performance of the control system, the linear displacement sensors and acceleration testing systems were used to analyze the performance of the seedling throwing. The results showed that the seedling picking efficiency could reach 180 plants min−1, with no significant difference between the actual measured moving distance and the theoretical setting distance. The positioning error remained stable between 0.5 and 0.9 mm, which met the requirements for seedling picking accuracy. The buffer optimization design reduced the peak acceleration of the end-effector from −22.1 m/s2 to −13.4 m/s2, and the peak value was reduced by 39.4%, which proved the significant effectiveness of the buffer design. A performance test was conducted using 128-hole seed trays and 33-day-old cabbage seedlings for seedling picking and throwing. When the planting frequency reached 90 plants/row·min−1, the average success rate of picking and throwing seedlings was 97.3%. This indicates that the various components of the designed seedling pick-up device work in good coordination during operation, and the control system operates stably. Technical requirements for the automatic mechanical transplanting of tray seedlings were achieved, which can provide reference for research on automatic transplanting machines.

Pepper transplanting mechanisms and kinematic simulation analysis: A review

Pepper production plays a significant role in the global agricultural economy, yet traditional manual transplanting methods lead to labor intensity challenges, inconsistency, and time constraints. Transplanting mechanisms of pepper transplanters significantly affect the efficiency of the entire transplanting process. This study reviewed the available transplanters used in pepper seedling transplantation, transplanting mechanisms, and the kinematic simulation analysis. Pepper transplanters are categorized into manual, semi-automatic, and fully automatic types. Manual types include handheld and pulling types, while semi-automatic types involve manually seedling feeding with automatic planting such walking-behind, riding, and tractor-drawn models. Fully automatic transplanters synchronize seedling extracting, transfer to the conveyor, and continuous planting into the soil. Picking mechanism utilize pick-up pins, pushing action, and grippers, while planting mechanism is achieved through link-driven, wheel-driven, and rotary gear-driven hoppers. Recent advancements have emphasized 4- and 5-bar pick-up pin-type link-driven hoppers with 1 or 2 degrees of freedom for efficient seedling handling and planting. Kinematic simulation analysis emerges as a crucial tool used by engineers to better understand complex interactions, identify strengths and weaknesses in designs for the evaluation and optimization of mechanisms by modelling forces, motion, and system behavior. The transplanting mechanisms survey, the role of kinematic simulation, and key trends involved, such as increased automation, precision planting, and the integration of sensor technologies, could provide valuable information to farmers and manufacturers for identifying current gaps and improvement areas for enhancing innovation in pepper production.

Development of Simplified Seedling Transplanting Device for Supporting Efficient Production of Vegetable Raw Materials

Efficient greenhouse production has a great supporting role in the development of vegetable agricultural and sideline product processing. In this paper, a simplified automatic transplanting device was designed and evaluated in a laboratory. The device mainly consists of a seedling pick-up gripper, a transplanting manipulator, two conveyors and a control system. The flexible multi-pin gripper was designed to effectively grasp, hold, and release seedlings. Through a combination innovation of the linear modules, the transplanting manipulator was designed to move the seedling gripper to the desired working position. The conveyors were the pallet-type double-row chain transmission system for automatic feeding of plug trays and growth pots. The control system was developed to coordinate each of the aforementioned function units. The multi-factor orthogonal and transplanting performance experiments were carried out under the standard seedling agronomy. The results showed that the transplanting frequency and the pick-up depth significantly affected the transplanting quality. When the transplanting frequency was 15 plants/min, the tightened spring force was 1.2 N, and the pick-up penetration depth was 35 mm, the optimum effects of automatic transplanting seedlings could be achieved. The maximum success in transplanting seedlings was 95.47% for local vegetable crops. The developed prototype could realize less waste of seedling resources at the farm level.

基于 EDEM 的顶杆输送带式取苗机构优化设计

In the seedling extraction mechanism of the ejection type, because the ejector rod is in direct contact with the seedling substrate, the fragmentation rate of the seedling is high, the success rate is low, and the seedling effect is poor. In order to solve this problem, combined with the interaction between the ejector rod and the bowl seedling, this paper analyzes the working principle of the ejector rod conveyor belt seedling harvesting mechanism, and optimizes the design of the ejector rod conveyor belt seedling harvesting mechanism. By using the method of EDEM simulation analysis and orthogonal experiment, taking the breaking rate and success rate of bowl seedling as the test response index, the effects of ejector rod end form, ejector rod diameter and seedling extraction speed were studied, and the results were analyzed by range analysis and variance analysis to analyze the influence law of the interaction of various factors on bowl seedling extraction. The simulation results show that the crushing rate of bowl seedlings increases with the increase of seedling speed and the decrease of ejector diameter. Among the three different types of ejectors, the effect of round head ejector is the best. The best parameter combination of the seedling mechanism is the diameter of the ejector rod 10mm, the seedling speed 2m/s, and the ejector rod in the form of round head ejector rod. The verification experiment shows that the seedling extraction effect of the optimized seedling extraction mechanism is better than that of the original seedling extraction mechanism. The results show that when the best combination of working parameters is used to collect seedlings, the qualified rate of seedlings is not less than 90%, the fragmentation rate is not higher than 20%, and the seedling performance is relatively stable. The optimized seedling extraction mechanism can be used in the automatic dryland bowl seedling transplanter to meet the operational requirements of the automatic transplanter.

A Fast Path Planning Method of Seedling Tray Replanting Based on Improved Particle Swarm Optimization

In the factory nursery, qualified seedlings can be used to replant unqualified seedlings or missing seedlings in the seedling tray through automatic transplanters. Due to the random positions of unqualified and missing seedlings, the end effector of the automatic replanting machine spends substantial time shuttling between the supply tray and the target tray to complete the replanting task. Therefore, we proposed a fast path planning method based on improved particle swarm optimization and compared it with the fixed sequence method and genetic algorithm in experiments with different replanting numbers in different tray types. The experiment shows that the improved particle swarm optimization algorithm and genetic algorithm can shorten the length of the replantation path by about 20% compared with the fixed sequence method, and the running time of the improved particle swarm optimization algorithm is 57.63% less than the genetic algorithm on average. The replanting path optimization method based on improved particle swarm optimization designed in this research can significantly optimize the length and time of the replanting path of the seedling tray, improve the efficiency of the replanting operation, and meet the real-time requirements.

Design and Test of a Lateral-Approaching and Horizontal-Pushing Transplanting Manipulator for Greenhouse Seedlings

Highlights A lateral-approaching and horizontal-pushing automatic transplanting manipulator was developed on the basis of cultural practice for vegetable production. The transplanting manipulator approached the seedlings using a circuitous path, which could get away from the seedling plants for extraction with low damages. Based on the modern mechatronics and pneumatic technology, a set of control system was designed to coordinate each function unit for flexible automation. Abstract. A lateral-approaching and horizontal-pushing transplanting manipulator for greenhouse seedlings was developed to minimize the damage of their stems and leaves during transplanting. The manipulator is composed of a pick-up robotic arm, an end-effector, two conveyors, and a control system. The robotic arm liking a spatial 3-DoF displacement mechanism to achieve a point-to-point circuitous locomotion of the end-effector was designed with the mechanism combination innovation method, which consisted of two crossing high-speed linear modules and a pushing slide cylinder. The end-effector of a pincette-type mechanism uses two cylinder fingers and four pins to pick up and release the seedlings. Each conveyor adopts a flat-belt transmission mode to move the plug tray/growth pot to the working position of the end-effector. The control system coordinates the flexible automation of each component. A physical prototype of the manipulator was constructed and its performance was tested under laboratory conditions. Through the high-speed camera test, the end-effector could approach plug seedling in lateral sliding way to effectively shelter the seedling plants. On the whole, the maximum holding angles of these seedling plants were larger than 45° with little effects on the subsequent growth. The corresponding performance tests showed that the average success ratios for automatic transplanting were up to 97.57% for typical pepper and cabbage seedlings. The lateral-approaching and horizontal-pushing transplanting performance was satisfactory. Keywords: Circuitous path, Greenhouse production, Low damage, Plug seedling, Transplanting.

Design and Working Parameter Optimization of Pneumatic Reciprocating Seedling-Picking Device of Automatic Transplanter

To improve the seedling-picking efficiency of the vegetable transplanter and reduce the damage rate of the seedling pot, a reciprocating seedling-picking device driven by full air pressure was designed. In this paper, the structure and working principle of the pneumatic seedling-picking device are introduced. Through the mechanical analysis between the seedling-picking claw and the seedling pot, working parameters such as the stroke and driving force of the pneumatic seedling-picking claw clamping cylinder were determined. According to the action sequence of the seedling-picking mechanism, which is horizontally dispersed and longitudinally conveyed, the pneumatic control scheme of the seedling-picking and -dropping system was formulated. The simulation model for the control loop of the longitudinal cylinder was created with AMESim simulation software, and the simulation analysis was carried out. The Box–Behnken response surface design optimization method was used to determine the best operating parameters of the cylinder. The optimized peak value of shock vibration at the end of the cylinder was optimized from −65.64 mm·s−2 to 35.41 mm·s−2, proving that the optimization of pneumatic working parameters has a positive effect on the success rate of seedling picking. The bench test of the seedling-picking mechanism was conducted on 72-hole plug seedlings with two picking frequencies of 120 plants·min−1 and 144 plants·min−1, respectively, and the average seedling leakage rate, seedling damage rate, and seedling pot damage rate at different picking frequencies were counted. The experimental results show that under the two seedling-picking frequencies, the average success rate of seedling picking and throwing after optimization is increased from 96.4% and 92.4% to 97.9% and 95.3%, respectively. This is in line with the requirements of high-speed seedling picking and confirms the rationality of the seedling-picking mechanism design.

Detection Method and Experimental Research of Leafy Vegetable Seedlings Transplanting Based on a Machine Vision

In view of the need to remove empty cells and unqualified seedlings for automatic transplanting of leafy vegetable seedlings, this paper proposes a method to detect the growth parameters of leafy vegetable seedlings by using machine vision technology. This method uses the image processor PV200 to perform image grayscale, threshold segmentation, corrosion, expansion, area division, etc. to obtain the pixel value of the leaf area of the seedling and compare it with the set standard value, which provides guiding information for eliminating empty cells and unqualified seedlings. Lettuce seedlings at 17 days, 20 days, and 22 days of seedling age were used as the test objects, and the growth status and test results of the seedlings were analyzed to determine the optimum seedling age for transplanting. The test results show that there is basically no leaf cross-border between the lettuce seedlings at the age of 17 days, the average pixel area of the leaves is 3771.74, and the detection accuracy rate is 100%; the seedlings at the age of 22 days grow 5–6 leaves, the detection accuracy of unqualified seedlings and qualified seedlings was 62.50% and 88.16%, respectively, and the comprehensive detection accuracy was 85.71%. The comprehensive detection accuracy rate showed a downward trend with the increase of seedling age, mainly due to the partial occlusion between leaves. The transplanting of leafy vegetable seedlings is a sparse transplanting operation, and the seedling spacing increases after transplanting. Therefore, the detection of seedlings in the process of transplanting can greatly improve the recognition accuracy and solve the problem that the leaves of the seedlings in the seedling tray are obscured by each other and affect the detection accuracy. The research results can provide a theoretical basis and design reference for the development of the visual inspection system and the transplanting actuator of the leafy vegetable seedlings transplanting robot.

Effects of Compound Biochar Substrate Coupled with Water and Nitrogen on the Growth of Cucumber Plug Seedlings

Since plug seedlings play a key role in automatic transplanting, this work aimed to explore the interaction between the biochar rate, water content, and N–fertilization in the substrate on the cultivation of cucumber seedlings before and after transplanting. The research showed that most of the factors obtained significant individual and interaction effects by measuring and analyzing the growth parameters of seedlings before transplanting. Most growth parameters significantly decreased with the increase in biochar rate except Water Use Efficiency which obtained the highest value of 2.06 g/L when the biochar rate was 10%. Furthermore, some growth parameters increased significantly with the increase in water content, while the Total Dry Matter and Water Use Efficiency reached their highest values, 0.778 g and 1.94 g/L, respectively, when the water content was 65%. All growth parameters reached their highest values when the N–fertilization was 50%; too high or too low of N–fertilization was not conducive to the growth of seedlings. The growth parameters and photosynthesis indices of seedlings cultivated after transplanting indicated that the seedlings with superior growth before transplanting performed better than other treatments in regard to growth and photosynthesis after transplanting. The interactions were in general optimal when the biochar rate was 5%, water content was 80%, and N–fertilization was 50% in the substrate, and seedlings cultivated under this treatment could not only meet the requirements of automatic transplanting, but also ensure rapid growth after transplanting. This study thus provides some guidance for the effective cultivation of vegetable plug seedlings.

Design and Test of A Force Feedback Seedling Pick-Up Gripper for An Automatic Transplanter

Aiming at the problems of seedling injury and planting leakage due to the lack of seeding clamping force detection and real-time control in vegetable transplanting, a force feedback gripper was developed based on the linear Hall element. The mechanical properties of the stem of pepper cavity seedlings were first analyzed to provide a basis for the design of the gripper. A linear Hall sensor, a magnet, an elastic actuator, and an Arduino Uno development board make up the grasping force detecting system. Upon picking up a seedling, the elastic actuator, which is connected to the magnet, bends like a cantilever beam. As a result of the micro-displacement created by the elastic actuator, the Hall sensor’s voltage changes and can be used to determine the clamping force. Detection avoids direct contact between the sensor and the cavity seedlings, reducing the risk of sensor damage. Finite element method (FEM) simulations were used to determine the initial spacing between the magnet and Hall sensor and the effect of the elastic actuator. Control commands are sent to the servo based on the gripping force collected by the Arduino Uno board. Finally, the functions of accurate measurement, display, storage, and control of the clamping force of the cavity tray seedlings are realized, so that the damage rate of the cavity tray seedlings is reduced. In order to explore the influence of the elastic actuators on the clamping force detection system and the performance of the force feedback gripper, a calibration test of the clamping force detection system and a test of the indoor transplantation of pepper seedlings were carried out. Based on the calibration test, the clamping force detection system has a sensitivity of 0.0693 V/N, linearity of 3.21%, an average linear coefficient of determination of 0.986, and a range of 10 N, which fully meet the clamping force detection accuracy requirements during transplantation. Indoor tests showed that the force feedback gripper was stable and adaptable. This study can provide a reference for detecting and controlling clamping forces during transplantation.

Theoretical transmission analysis to optimize Gearbox for a 2.6 kW automatic pepper transplanter

A gearbox is an essential component of an automatic transplanter to transmit engine power to the transplanter components. It is necessary to find the appropriate gearbox dimensions and materials for the pepper transplanter to minimize transmission losses. Therefore, the objectives of this research were to simulate the power transmission efficiency of the gearbox, and to determine a suitable number of stages, and materials and the dimensions of the spur gears. A 2.6 kW gasoline engine was considered as the prime source to power the entire transplanter. The available maximum length between the engine and transplanter subsystem was 422 mm. By considering design issues, a simulation model was created to determine the efficiency of the pepper transplanter gearbox, including various types of mechanical losses in the gearing system. Three different modules (1, 2, and 3 mm) and two materials were used to evaluate the effects on transmission. The analysis results indicated that the gearbox transmission efficiency levels of seven to twelve stages were in the range of 93.0–98.7%, whereas the eight-stage gearbox yielded the maximum efficiency of 98.7%, greater than our target efficiency of 98.0%. Therefore, an eight-stage gearbox was selected for power transmission to the components. The power transmission simulation results showed that the overall efficiency from engine to transplanting mechanism shaft varied in range of 95.2–95.9% owing to contact of the gear meshes. The analysis results also indicated that the 25CrMo4 carbon steel material with a 2-mm module gear was appropriate for the pepper transplanter. The analysis in this paper can be used as reference in the design of pepper transplanter gears and gearboxes with suitable material properties to provide the desired efficiency.

Optimizing the Path of Plug Tray Seedling Transplanting by Using the Improved A* Algorithm

In greenhouse nurseries, one of the important tasks of the automatic transplanter is replanting missing or bad seedling holes with healthy seedlings. This requires the transplanter to spend significant time moving between the supply trays and target trays during replanting. The diversity and complexity of the transplanting routes affect transplanter efficiency. Path planning method can find a better path for the manipulator and improve the efficiency of transplantation. The A* algorithm (A*), which is one of the optimal path search algorithms, is often used in practical applications of path planning. In this paper, the heuristic function of the A* is optimized by the ant colony algorithm (ACA), and an improved A* algorithm (Imp-A*) is obtained. Simulation tests and transplanting trials of Imp-A*, A*, ACA, Dijkstra (DA), and common sequence method (CSM) were carried out using 32-, 50-, 72-, and 128-hole plug trays. The results show that Imp-A* inherits the advantages of A* and ACA in terms of path planning length and computation time. Compared to A*, ACA, DA, and CSM, the transplanting time for Imp-A* was reduced by 2.4%, 12.84%, 11.63%, and 14.27%, respectively. In just six trays of transplanting tasks, Imp-A* saves 60.91 s compared to CSM, with an average time saving of 10.15 s per tray. The combination optimization algorithm has similar application prospects in agriculture.

Optimal design and experimental verification of a four-claw seedling pick-up mechanism using the hybrid PSO-SA algorithm

Aim of study: To develop a novel four-claw seedling pick-up mechanism to integrate penetration and clamping into one process, realizing picking up seedlings stably and efficiently.
 Material and methods: A brushless DC servo motor characterized by small size, large torque, and high control precision was adopted to realize precise control for speed and clamping force through control algorithms. An optimization model was derived according to the requirements of picking up seedlings. The parameter optimization of the seedling pick-up mechanism is a complex multi-parameter and nonlinear optimization problem. The hybrid PSO-SA algorithm was used to solve the model, and the optimal parameters of the mechanism were obtained.
 Main results: The dynamic simulation was conducted, and the results showed that the optimized mechanism could meet the trajectory, acceleration, and clamping force requirement for picking up seedlings. The performance tests showed that the success ratio in picking up seedlings reached 84.46%, indicating the feasibility of the four-claw seedling pick-up mechanism for automatic transplanting machines.
 Research highlights: The four-claw seedling pick-up mechanism can be used in the automatic transplanting machine. Additionally, the hybrid PSO-SA algorithm can achieve promising results in solving the optimization problem of the seedling pick-up mechanism.

Factors influencing the performance of mechanical end effector during automatic transplanting of tomato seedlings

A number of elements of probabilistic nature mightily influence the picking efficiency of a transplanting mechanism. There are two key factors to be considered in the development of seedling pickup devices. One is the mechanical features of the end effector, and the other is the horticultural features of the protray seedling. The investigation aimed to find the features affecting the transplanting of protray grown tomato seedlings using mechanical end-effectors. Various mechanical linkage-picking fingers were developed and tested with an experimental setup for gripping and releasing the seedling. Two different pneumatic cylinders triggered the mechanical end effector, one for holding the seedling and then ejecting the seedling from the protray. When all the seedlings were ejected from the initial line of the protray, the endless belt shifted the protray just below the end-effector mechanism. Assessments were carried out with moisture content of media (16 ±1, 18 ±1 and 21 ±1%), mechanical end-effector (sliding plate cam type, sliding end cam type and four bar type picking finger) angle of end-effector needle (6, 8 and 10 deg.) to enhance the picking, transmission and dropping with low missing as well as harms for the seedlings. The minimum value of missing seedlings (6.55 %) and maximum success rate of picking (93.45 %) were noted at 18 ±1% of the growth media moisture content (M2) and at 8 deg. angle of gripper needle (θ2) with a sliding plate cam-type picking finger (F1). The transplanting frequency was 840 seedlings h-1.

Opening and Closing Positioning Control of the Seedling Picking-Up Mechanism Based on Fuzzy-PID Control Algorithm

The success rate of automatic transplanter seedling picking is affected by the harsh operating environment of the transplanter and the reduced output accuracy of the opening and closing positioning of the seedling-picking mechanism due to the interference of the external environment. To solve such problems, the paper proposes to use an adaptive fuzzy PID control algorithm as the opening and closing positioning-control system of the seedling-picking mechanism. Based on the theoretical analysis and calculation of the positioning accuracy of the seedling-picking mechanism, a mathematical model of stepper motor angular velocity control was established, and a stepper motor angular velocity control model based on fuzzy PID (conventional PID) control was established in MATLAB/Simulink. In order to further simulate the actual working condition of the seedling-picking mechanism, a simulation model of stepper motor control with disturbance was built, and the response results showed that the fuzzy PID control system could get rid of the disturbance faster under the action of external disturbance signals. The results of the opening and closing positioning test of the seedling-picking mechanism showed that the fuzzy PID control system has higher control accuracy and more stable control performance than the PID control system, which meets the design requirements.