Seedling density self-adaptive adjusting device for rice transplanter and adjusting method thereof

Abstract

An adaptive seedling density adjustment device and control method for a rice transplanter are disclosed. The device includes a chassis, a seedling separating mechanism, a seedling delivery platform, a planting mechanism consisting of several planting units, a continuously variable transmission (CVT) drive mechanism consisting of independent drive units, and an adaptive adjustment system. The system includes a seedling density sensing module, a speed sensing module, and a controller. The controller calculates the base rotation speed based on the traveling speed and the target plant spacing. The density sensing module obtains real-time seedling quantity information for each conveying area on the seedling delivery platform. A predictive overall seedling density index is generated through a spatial distance-weighted grid partitioning and anomaly removal algorithm. The system then determines the compensation amount and independently adjusts the rotation speed of each CVT motor, dynamically changing the planting frequency of the corresponding planting unit. This invention achieves independent feedforward sensing of seedling density in each row and adaptive compensation for plant spacing. It has a compact structure, significantly reduces the missed planting rate, and improves the uniformity of planting in the field.

Description

Technical Field

[0001] This invention relates to the field of agricultural machinery technology, specifically to a seedling density adaptive adjustment device and adjustment method for a rice transplanter. Background Technology

[0002] One of the core performance indicators for rice transplanters is the uniformity of transplanting, including the consistency of the number of seedlings per hill and the stability of the plant spacing. Traditional rice transplanters typically use mechanical transmission, achieving a fixed plant spacing setting by changing gear sets or manually adjusting the hydraulic motor displacement, and cannot be dynamically adjusted in real time.

[0003] The planting transmission device disclosed in Chinese patent CN107711005A requires manual gear shifting after the machine is stopped; the hydraulic system disclosed in CN203279493U relies on manual adjustment and lacks automatic sensing capabilities; the vision solutions disclosed in CN109405757B, etc., all perform post-planting detection on seedlings that have already been planted in the field, which is a form of delayed control. The hydraulic control system of the unmanned rice transplanter disclosed in Chinese patent CN222415441U aims to maintain a constant plant spacing and does not involve sensing seedling density or independent compensation for each row.

[0004] In summary, the existing technology has the following significant drawbacks:

[0005] First, the adjustment process is cumbersome and often requires stopping the machine, making it impossible to make dynamic adjustments based on real-time changes in seedling quality, transport status, etc.

[0006] Secondly, it is an open-loop control system, which cannot sense the actual seedling supply status. The amount of seedlings picked up by the transplanting mechanism will fluctuate drastically due to factors such as seedling density and root plate tightness; if the picking fails, it will result in missed planting, and if it picks up too many, it will waste seedlings and affect tillering.

[0007] Third, while existing technologies have attempted variable-rate planting using satellite positioning and prescription maps, these systems are complex and cannot respond in real time to dynamic changes caused by uncertain factors such as machine vibration and seedling condition. Furthermore, for multi-row rice transplanters, the seedling supply status of each row often differs, making it impossible to achieve precise compensation for each row through uniform adjustment.

[0008] Fourth, some existing solutions propose a delayed control approach that involves visually inspecting and providing feedback on transplanted seedlings. However, this approach only detects missed plantings after the defects have already occurred, making it impossible to make proactive adjustments before the planting process takes place. Summary of the Invention

[0009] The purpose of this invention is to provide a seedling density adaptive adjustment device and its control method for rice transplanters, so as to solve the technical problem that the existing technology cannot dynamically compensate the plant spacing according to the independent seedling density of each conveying area on the seedling delivery platform, resulting in a high rate of missed planting and poor uniformity of planting in each row.

[0010] To solve the above-mentioned technical problems, the present invention provides the following technical solution:

[0011] A seedling density adaptive adjustment device for a rice transplanter includes a chassis, a seedling separating mechanism installed on one side of the chassis and arranged at an angle, a seedling feeding platform installed on the chassis and located at the input end of the seedling separating mechanism, and a planting mechanism installed on the chassis and located below the seedling separating mechanism.

[0012] The seedling delivery platform is used to deliver seedlings to the seedling separating mechanism. The transplanting mechanism consists of several transplanting units, which are used to transplant the seedlings output from the end of the seedling separating mechanism.

[0013] The adaptive adjustment device further includes a continuously variable transmission (CVT) drive mechanism for controlling the operation of the insertion mechanism. The CVT drive mechanism is composed of several drive units, each drive unit corresponding to one of the insertion units, and the drive unit is connected to the corresponding insertion unit in a transmission manner.

[0014] The adaptive adjustment device further includes an adaptive adjustment system, which includes: at least one seedling density sensing module whose field of view covers a preset area upstream of the seedling delivery platform and the seedling separating mechanism, for real-time acquisition of seedling quantity information characterizing the seedling distribution density in the area; a speed sensing module for acquiring the real-time travel speed of the rice transplanter; and a controller connected to the seedling density sensing module, the speed sensing module, and the continuously variable transmission drive mechanism.

[0015] The controller is configured to: dynamically calculate the required base rotation speed at the output of the planting mechanism based on the real-time travel speed and a target; generate an overall seedling density index based on the seedling quantity information, and compare this density index with a preset standard density range to determine a compensation amount for compensating for grasping quantity deviation; superimpose the base rotation speed and the compensation amount to calculate the target transmission ratio, and output a corresponding control signal to the continuously variable transmission drive mechanism to continuously adjust the actual planting frequency of the planting unit, ultimately achieving adaptive compensation.

[0016] When generating the overall seedling density index, the controller performs the following operations: dividing the image or point cloud data of the preset area into multiple grids; assigning a spatial weight coefficient to each grid based on the distance between each grid and the top of the seedling separating mechanism, where the closer the distance, the higher the weight; calculating the local density metric value of each grid and removing abnormal grids caused by soil or water stains; and weighting the local density metric values ​​of all valid grids according to their spatial weight coefficients to obtain the overall seedling density index.

[0017] Furthermore, the seedling separating mechanism includes a support frame, an inclined plate, a guide plate, and seedling separating covers. The support frame is fixedly connected to the chassis, the inclined plate is fixedly connected to the support frame, the guide plate is connected to the upper end of the inclined plate, and the guide plate is located below the output end of the seedling feeding platform. Several seedling separating covers are connected to the inclined plate, and a channel for accommodating the downward sliding of seedlings is formed between the seedling separating covers and the inclined plate. The lower end of the inclined plate is provided with a baffle perpendicular to it, and several seedling picking openings corresponding to the channels are opened on the baffle plate. The seedling picking openings are located below the corresponding channels.

[0018] Furthermore, the seedling delivery platform includes a belt conveyor, which is installed on both sides of the chassis via a frame. The output end of the belt conveyor is located above the guide plate, and the input end of the belt conveyor extends to the rice transplanter. Several limiting strips are fixed on the conveyor belt of the belt conveyor, and a conveying area corresponding to the channel is formed between adjacent limiting strips.

[0019] Furthermore, the planting unit includes a first bearing seat, a first drive shaft, a second bearing seat, a second drive shaft, a third bearing seat, a third drive shaft, a planting arm, and a seedling picking mechanism.

[0020] The drive unit includes a continuously variable motor, a first sprocket, a second sprocket, a first chain, a third sprocket, a fourth sprocket, and a second chain.

[0021] Two first bearing seats are fixedly connected to the chassis, and the first drive shaft is rotatably connected to the two first bearing seats through bearings. The output end of the continuously variable motor is connected to one end of the first drive shaft. Two second bearing seats are fixedly connected to the chassis and are close to the inclined plate. The second drive shaft is rotatably connected to the two second bearing seats through bearings.

[0022] The first sprocket is mounted on the first drive shaft, and the second sprocket is mounted on the second drive shaft. The diameter of the second sprocket is larger than the diameter of the first sprocket, and the first sprocket and the second sprocket are connected by a first chain drive.

[0023] Two third bearing seats are mounted on the lower end of the support frame, and the third drive shaft is rotatably connected to the two third bearing seats through bearings; a third sprocket is mounted on one end of the second drive shaft, and a fourth sprocket is mounted on the third drive shaft, and the third sprocket and the fourth sprocket are connected by a second chain drive.

[0024] The insertion arm includes a hinge seat, a connecting rod, and an L-shaped lever pivotally connected to the connecting rod. The hinge seat is fixedly connected to the chassis. One end of the connecting rod is pivotally connected to the hinge seat, and one end of the lever is pivotally connected to one end of the connecting rod. A pin is connected to one side of the second sprocket, and the lever body is pivotally connected to the pin. The end of the lever away from the connecting rod has a V-shaped opening. The chassis has several toothed openings on the side facing the third drive shaft to accommodate the lever's up-and-down movement within them.

[0025] The seedling-harvesting mechanism includes a cam plate, a seedling-harvesting rod, a spring, a limiting rod, and a seedling-harvesting claw. One side of the cam plate is connected to the lower part of the support frame by screws. The seedling-harvesting rod is fixedly connected to the third transmission shaft and is located on one side of the cam plate. The seedling-harvesting rod and the cam plate are located diagonally below the seedling-harvesting opening. The seedling-harvesting claw is L-shaped, with its lower end movably connected to the seedling-harvesting rod. A spring is installed inside the seedling-harvesting rod, and the lower end of the seedling-harvesting claw is connected to the spring. The upper end of the seedling-harvesting claw forms a clamp with the seedling-harvesting rod. The device includes a clamping mechanism for holding seedlings that fall from the seedling-taking opening; a limiting rod is connected to the seedling-taking claw, and the seedling-taking rod has a strip-shaped sliding hole on its shaft, within which the limiting rod is slidably positioned; the inner wall of the cam disk is convex, and one end of the limiting rod is located inside the cam disk, and is pressed against the inner wall of the cam disk by a spring; the seedling-taking rod corresponds to the lever, and is located on one side of the plane of the corresponding lever, through which the seedlings grasped by the seedling-taking claw are inserted into the soil.

[0026] Furthermore, the seedling density sensing module includes several visual sensors, which are mounted on a frame at a position higher than the belt conveyor. Each visual sensor corresponds to a conveying area between two adjacent limit bars, and the visual sensor is located above the corresponding conveying area.

[0027] The seedling quantity information is an image of the preset area; the controller analyzes the texture features or color area ratio of the image through an image processing algorithm to obtain the local density metric value of each grid.

[0028] Furthermore, a protective cover is connected to the chassis. The first bearing housing, the first drive shaft, the continuously variable motor, the second bearing housing, and the second drive shaft are all located inside the protective cover. One side of the protective cover is provided with a first opening to accommodate the rotation of the lever and a second opening to accommodate the operation of the second chain.

[0029] Furthermore, both the chassis and the mounting frame are connected to a connecting seat, which is connected to the rice transplanter.

[0030] Furthermore, the spatial weight coefficients are preset as follows: the grid weight corresponding to the first sub-region closest to the guide plate is 1.0, the grid weight corresponding to the second sub-region in the middle is 0.8, and the grid weight corresponding to the third sub-region furthest from the guide plate is 0.5.

[0031] Furthermore, it also includes an input module connected to the controller for receiving the target set by the operator.

[0032] This invention also provides a method for adaptive adjustment of seedling density in a rice transplanter, implemented based on the aforementioned device, comprising the following steps:

[0033] S1: Parameter initialization: Obtain the preset target in each delivery area and establish a model of the correspondence between seedling density level and compensation amount;

[0034] S2: Real-time signal acquisition: Continuously acquire the real-time travel speed of the rice transplanter and the real-time seedling quantity information of the preset area at the end of the seedling delivery platform;

[0035] S3: Base rotation speed calculation: Based on the real-time travel speed and target, the base rotation speed required for the implantation arm is calculated in real time;

[0036] S4: Compensation Decision: Analyze the real-time seedling quantity information in each conveying area to generate an overall seedling density index. Specifically, this includes: dividing the preset area into multiple grids, and assigning a spatial weight coefficient to each grid based on the distance between each grid and the top of the seedling separating mechanism. The method for assigning the spatial weight coefficient to each grid is as follows: the preset area is divided into near zone, middle zone, and far zone along the seedling conveying direction. The weight of the near zone grid is set to 1.0, the weight of the middle zone grid is set to 0.8, and the weight of the far zone grid is set to 0.5.

[0037] Calculate the local density metric value for each grid and remove abnormal grids. Take a weighted average of the local density metrics values ​​of all valid grids to obtain the overall seedling density index. Compare the density index with the preset standard density range. When the density index is lower than the first threshold, generate a negative compensation amount. When the density index is higher than the second threshold, generate a positive compensation amount.

[0038] S5: Target transmission ratio calculation and execution: The base speed and the compensation amount are superimposed to generate the target speed. Combined with the output speed of the continuously variable motor, the target transmission ratio that the continuously variable motor needs to achieve is calculated, and control commands are output to the continuously variable motor.

[0039] Compared with the prior art, the present invention has the following beneficial effects:

[0040] (1) By configuring an independent seedling density sensing module and a continuously variable drive unit for each conveying area, each planting unit can independently compensate for the spacing of its corresponding seedlings. When a row of seedlings is broken or sparse, only the planting unit corresponding to that row accelerates to compensate, while the other rows are unaffected, thus achieving true independent inter-row compensation.

[0041] (2) Enhancing predictability and accuracy through spatial weighting: When generating the density index, a spatial weighting mechanism based on the distance between the grid and the top of the seedling separating mechanism is introduced. The closer the grid is, the higher its weight, so that the density index can preferentially and sensitively reflect the status of the seedlings that are about to enter the seedling picking port. This makes the compensation decision more predictable and real-time, and can be avoided before missed planting occurs. Attached Figure Description

[0042] Figure 1 This is a schematic diagram of the present invention;

[0043] Figure 2 for Figure 1 A diagram showing the result after the protective cover has been removed;

[0044] Figure 3 for Figure 2 Top view after removing the seedling separating mechanism;

[0045] Figure 4 This is a magnified view of a portion of the seedling-collecting mechanism and the seedling-separating mechanism;

[0046] Figure 5 This is a schematic diagram of the seedling-harvesting mechanism;

[0047] Figure 6 A breakdown diagram of the rice planting process;

[0048] Figure 7 This is the logic diagram of an adaptive adjustment system;

[0049] In the diagram: 1-chassis, 11-toothed mouth, 2-seedling separating mechanism, 21-support frame, 22-sloping plate, 23-guide plate, 24-seedling separating cover, 25-channel, 26-baffle, 27-seedling picking port, 3-seedling delivery platform, 31-belt conveyor, 32-frame, 33-limiting strip, 34-conveying area, 4-planting mechanism, 41-first bearing seat, 42-first drive shaft, 43-second bearing seat, 44-second drive shaft, 45-third bearing seat, 46-third drive shaft, 47-planting arm, 471-hinge seat, 472-connecting rod, 473-lever. 474-V-shaped opening, 48-Seedling picking mechanism, 481-Cam plate, 482-Seedling picking rod, 483-Limiting rod, 484-Seedling picking claw, 485-Sliding hole, 5-Continuously variable speed drive mechanism, 51-Continuously variable speed motor, 52-First sprocket, 53-Second sprocket, 54-First chain, 55-Third sprocket, 56-Fourth sprocket, 57-Second chain, 6-Adaptive adjustment system, 61-Seedling density sensing module, 611-Vision sensor, 612-Mounting frame, 7-Protective cover, 71-First opening, 72-Second opening, 8-Connecting seat. Detailed Implementation

[0050] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0051] Please see Figures 1 to 6 This embodiment provides a seedling density adaptive adjustment device for a rice transplanter, which is installed on the rear body of a ride-on high-speed rice transplanter via a connecting seat 8. The device mainly consists of a chassis 1, a seedling feeding platform 3, a seedling separating mechanism 2, a transplanting mechanism 4, a continuously variable transmission drive mechanism 5, and an adaptive adjustment system 6.

[0052] The chassis 1 is a welded frame structure, which serves as the load-bearing foundation for the entire device. Connecting seats 8 are connected to the upper rear end of the chassis 1 and the mounting frame 612 for attaching to the body of the rice transplanter (not shown in the attached diagram).

[0053] The seedling feeding platform 3 is used to carry and transport the blanket-shaped seedlings. In this embodiment, the seedling feeding platform 3 includes a belt conveyor 31, which is installed on both sides of the chassis 1 via a frame 32. The input end of the belt conveyor 31 extends to the rear operating platform of the rice transplanter (not shown in the attached figure). The operating platform is equipped with a seedling storage rack (not shown in the attached figure) for feeding seedlings into the belt conveyor 31. The output end of the belt conveyor 31 is located above the seedling separating mechanism 2. Several limiting strips 33 are horizontally fixed on the conveyor belt of the belt conveyor 31. An independent conveying area 34 is formed between adjacent limiting strips 33, and each conveying area 34 corresponds to a row of seedlings.

[0054] The seedling separating mechanism 2 is installed on one side of the chassis 1 and is inclined as a whole. It includes a support frame 21, an inclined plate 22, a guide plate 23, and seedling separating covers 24. The support frame 21 is fixedly connected to the chassis 1, the inclined plate 22 is fixedly connected to the support frame 21, and the guide plate 23 is connected to the upper end of the inclined plate 22 and located below the output end of the belt conveyor 31. Several seedling separating covers 24 are bolted or welded to the inclined plate 22, and each seedling separating cover 24 forms a channel 25 between itself and the inclined plate 22 to accommodate the downward movement of seedlings. The lower end of the inclined plate 22 is provided with a baffle 26 perpendicular to it, and the baffle 26 has several seedling picking openings 27 corresponding one-to-one with the channels 25, and the seedling picking openings 27 are located directly below the corresponding channels 25. In order for the seedlings to slide smoothly down the inclined plate 22 under gravity without stopping, the inclination angle of the inclined plate 22 needs to be greater than 60°.

[0055] The planting mechanism 4 is mounted on the chassis 1 and located below the seedling separating mechanism 2, and consists of multiple planting units. The continuously variable transmission drive mechanism 5 consists of multiple drive units, each drive unit corresponding to one planting unit and connected by transmission to achieve independent drive for each row.

[0056] Please refer to the following carefully. Figure 3 and Figure 4 The structure is described in detail using a set of insertion units and their corresponding driving units as an example.

[0057] The drive unit includes a continuously variable motor 51, a first sprocket 52, a second sprocket 53, a first chain 54, a third sprocket 55, a fourth sprocket 56, and a second chain 57.

[0058] The planting unit includes two first bearing seats 41, one first drive shaft 42, one second bearing seat 43, one second drive shaft 44, two third bearing seats 45, one third drive shaft 46, a set of planting arms 47, and a set of seedling picking mechanisms 48.

[0059] Two first bearing seats 41 are fixed to the chassis 1 by bolts, and the first drive shaft 42 is rotatably supported on the two first bearing seats 41 by bearings. The continuously variable motor 51 is a DC brushless speed-regulating motor, and its output end is connected to one end of the first drive shaft 42 through a coupling. The first sprocket 52 is fixedly mounted on the first drive shaft 42.

[0060] Two second bearing seats 43 are fixed on the chassis 1 and near the inclined plate 22. The second drive shaft 44 is supported on the two second bearing seats 43 by the bearings. The second sprocket 53 is mounted on the second drive shaft 44 and its diameter is larger than that of the first sprocket 52. The two are connected by the first chain 54 to form a first-stage reduction.

[0061] Two third bearing seats 45 are installed at the lower end of the support frame 21, and the third drive shaft 46 is rotatably supported on the two third bearing seats 45 through bearings. A third sprocket 55 is installed at one end of the second drive shaft 44, and a fourth sprocket 56 is installed on the third drive shaft 46. The third sprocket 55 and the fourth sprocket 56 are connected by a second chain 57 to form a two-stage reduction and transmit power to the seedling picking mechanism 48.

[0062] The planting arm 47 includes a hinge seat 471, a connecting rod 472, and a lever 473. The hinge seat 471 is fixed to the chassis 1, and one end of the connecting rod 472 is pivotally connected to the hinge seat 471. The lever 473 is L-shaped, and one end is pivotally connected to the other end of the connecting rod 472. A pin is provided at an eccentric position on one side of the second sprocket 53, and the body of the lever 473 is pivotally connected to this pin. When the second sprocket 53 rotates, it drives the lever 473 to move through the pin. At the same time, under the constraint of the connecting rod 472, the end of the lever 473 away from the connecting rod forms a contour planting trajectory. This end is provided with a V-shaped opening 474 for conveying seedlings. The side of the chassis 1 facing the third drive shaft 46 is provided with several toothed openings 11 to accommodate the lever 473 swinging up and down within them.

[0063] The seedling picking mechanism 48 includes a cam plate 481, a seedling picking rod 482, a spring (not shown in the figure), a limiting rod 483, and a seedling picking claw 484. A third drive shaft 46 passes through the center of the cam plate 481. One side of the cam plate 481 is fixedly connected to the lower part of the support frame 21 by screws and does not rotate with the third drive shaft 46. The seedling picking rod 482 is fixedly installed on the third drive shaft 46 and is located on one side of the cam plate 481. Both the seedling picking rod 482 and the cam plate 481 are located diagonally below the seedling picking opening 27. The seedling picking claw 484 is L-shaped, with its lower end movably inserted into the seedling picking rod 482. A spring is installed inside the seedling picking rod 482, with one end abutting against the inside of the feeding rod and the other end abutting against the lower end of the feeding claw 484, providing an elastic force to return it to its original position. The upper end of the seedling picking claw 484 and the upper end of the seedling picking rod 482 form a clamping part, used to clamp fallen seedlings at the seedling picking opening 27. The limiting rod 483 is fixed to the seedling-picking claw 484. A strip-shaped sliding hole 485 is formed on the shaft of the seedling-picking rod 482, and the limiting rod 483 slides within this hole 485. The inner wall of the cam disk 481 has a cam profile, and one end of the limiting rod 483 extends into the cam disk 481 and is always pressed against the inner wall under the action of a spring force. As the third drive shaft 46 drives the seedling-picking rod 482 to rotate, the limiting rod 483 slides along the inner wall of the cam disk 481, driving the seedling-picking claw 484 to switch between clamping and releasing states.

[0064] The spatial positions of the seedling-taking rod 482 and the lever 473 are coordinated: the plane of the seedling-taking rod 482 is close to the side of the movement plane of the lever 473. When the seedling-taking claw 484 clamps the seedling and turns downward, the V-shaped opening 474 of the lever 473 swings into position, pulling the seedling out of the seedling-taking claw 484 and inserting it into the soil.

[0065] The adaptive adjustment system 6 includes a seedling density sensing module 61, a speed sensing module, and a controller.

[0066] The seedling density sensing module 61 includes multiple vision sensors 611. Each vision sensor 611 is mounted above the belt conveyor 31 via a mounting bracket 612 and corresponds one-to-one with the conveying area 34 on the conveyor belt. The field of view of each vision sensor 611 vertically covers the end section of the conveying area 34, that is, a preset observation area located upstream of the seedling separating mechanism 2. The vision sensor 611 continuously acquires images of this area in real time as seedling density information for that row. In this embodiment, the vision sensor 611 is a high-resolution industrial camera, and a light shield and supplementary light can be added to the mounting bracket to ensure image quality.

[0067] The speed sensing module uses a ground speed radar (Doppler radar sensor) installed on the rice transplanter body. It uses the Doppler effect to emit microwaves to the ground and receive reflected waves. Based on the frequency difference, it calculates the real speed relative to the ground to provide real-time speed.

[0068] The controller is an on-board embedded controller, installed on the rice transplanter body, and connected to each vision sensor 611, speed sensing module, and continuously variable motor 51 via wiring harnesses. Additionally, a touch input module, also installed on the rice transplanter body, is included to allow the operator to set parameters such as target plant spacing.

[0069] To protect the transmission components and ensure safety, a protective cover 7 is connected to the chassis 1 by screws. The first bearing housing 41, the first drive shaft 42, the continuously variable motor 51, the second bearing housing 43, the second drive shaft 44, etc. are all enclosed within the protective cover 7. One side of the protective cover 7 has a first opening 71 to accommodate the rotation of the lever 473, and a second opening 72 to accommodate the operation of the second chain 57.

[0070] This invention also provides a method for adaptively adjusting seedling density in a rice transplanter, using the aforementioned adjusting device. The method includes the following steps:

[0071] S1: Parameter initialization. The operator sets the target plant spacing (e.g., 16cm) through the input module. The controller loads the correspondence model between seedling density level and compensation amount into memory. This model is calibrated from a large number of field trials.

[0072] S2: Real-time signal acquisition. During operation, the controller continuously acquires the rice transplanter's travel speed V, while each vision sensor 611 transmits real-time images of the observation area corresponding to the conveying area 34.

[0073] S3: Basic Rotation Speed ​​Calculation. The controller calculates the basic motor rotation speed Req_RPM for each planting unit based on the travel speed V and the target plant spacing D. The formula is Req_RPM = (V×1000 / 60) / (D×N)×i, where N is the number of plantings per revolution of each planting arm (1 in this embodiment), and i is the fixed total transmission ratio from the motor to the planting arm.

[0074] S4: Compensation Quantity Decision. This step is performed independently for each row.

[0075] (1) Image preprocessing: Denoise reduction and white balance correction are performed on the image of the camera, and the preset observation area is cropped out.

[0076] (2) Grid division and weight assignment: The observation area is divided into M×N grids. Based on the distance between each grid and the top of the seedling separating mechanism (i.e., the lower edge of the guide plate 23, the entrance for seedlings to enter the seedling picking port), a spatial weight coefficient is assigned to each grid. The area is divided into near zone, middle zone, and far zone along the conveying direction: near zone grid weight 1.0, middle zone grid weight 0.8, and far zone grid weight 0.5.

[0077] (3) Local density measurement: Convert the image to HSV space, extract the green component, and calculate the proportion of green pixel coverage area in each grid as the local density measurement value. At the same time, the texture entropy value is calculated to assist in the judgment.

[0078] (4) Abnormal mesh removal: Remove meshes in soil or water stain areas with a low green content (<5%) and low texture complexity, as well as water surface reflective meshes with an abnormally high green content (>98%) but extremely low texture.

[0079] (5) Weighted density index calculation: For all valid grids, according to the weights The overall seedling density index D of the transport area is obtained by performing a weighted average:

[0080]

[0081] (6) Compensation decision: Compare D with the preset standard density range. When D is lower than the first threshold, it indicates that the seedlings in this delivery area are sparse and there is a risk of missing the target area, and a negative compensation amount ΔC (e.g., -1.5cm) is generated; when D is higher than the second threshold, it indicates that the seedlings will soon be too dense, and a positive compensation amount ΔC (e.g., +1.2cm) is generated.

[0082] To clarify the quantitative relationship between the overall seedling density index and the compensation amount, this embodiment uses a piecewise linear mapping function. First, the seedling density index D is normalized to [0,1], and a standard density interval is preset as [Dmin,Dmax]=[0.45,0.75]. When D is within this interval, the seedling density is considered normal, and the compensation amount ΔC=0. When D<0.45, the seedlings are too sparse, resulting in negative compensation (reducing plant spacing), and the compensation amount is calculated using the following formula:

[0083] ΔC = -ΔC_max × (0.45 - D) / 0.45

[0084] Where ΔC_max is the maximum negative compensation amount, which is set to -2.5cm in this embodiment (i.e., the plant spacing is shortened by a maximum of 2.5cm). When D > 0.75, the seedlings are too dense, resulting in positive compensation (increasing the plant spacing). The compensation amount is calculated according to the following formula:

[0085] ΔC = +ΔC_max × (D - 0.75) / 0.25

[0086] Where ΔC_max is the maximum positive compensation amount, which is set to +2.0cm in this embodiment (i.e., the plant spacing increases by a maximum of 2.0cm). To ensure planting stability, the final plant spacing after compensation is limited to between the absolute minimum of 8cm and the absolute maximum of 25cm.

[0087] As another alternative mapping method, a discrete-level lookup table method can also be used, for example:

[0088] Density index range Compensation amount (cm) [0, 0.2) -2.5 [0.2, 0.35) -1.5 [0.35, 0.45) -0.8 [0.45, 0.75] 0 (0.75, 0.85] +0.8 (0.85, 0.95] +1.5 (0.95, 1.0] +2.0

[0089] Both of the above mapping methods have been verified to be effective in field trials. Those skilled in the art can select or calibrate specific parameters according to actual operational needs.

[0090] S5: Target transmission ratio calculation and execution. The theoretical plant spacing corresponding to the base speed is superimposed with ΔC to obtain the compensated virtual plant spacing. The target motor speed is then calculated. The controller sends a speed adjustment command to the continuously variable motor 51 corresponding to that row. The motor responds quickly, changes the planting frequency, and completes the adaptive compensation of the plant spacing for that row.

[0091] Through the aforementioned independent closed-loop control for each row, when seedlings in a certain row become broken or sparse, only the motor corresponding to that row speeds up, increasing the number of plantings to compensate for the risk of missed plantings; the remaining rows maintain the standard plant spacing. When the seedling density returns to normal, the compensation automatically resets to zero.

[0092] In specific operations, for example, during a field operation, a sparse area of ​​about 20cm appeared in the third-stage conveying area of ​​the belt conveyor 31 due to uneven seedling cultivation. When this area entered the observation zone, the green coverage rate of the nearby grid dropped sharply, and the weighted density index D of that row quickly fell below the first threshold. The controller immediately issued an acceleration command to the third continuously variable transmission motor, and the planting frequency of that row increased by about 5% instantaneously. Although the number of seedlings per hole decreased, the number of planting holes per unit distance increased due to the dynamic reduction in plant spacing, effectively avoiding consecutive missed plantings. The operation of the other rows was unaffected. When the density returned to normal, the motor speed of that row automatically returned to the standard value, and the process was smooth and without any interruptions.

[0093] It should be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0094] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A seedling density adaptive adjustment device for a rice transplanter, characterized in that, Includes a chassis (1), a seedling separating mechanism (2) installed on one side of the chassis (1) and inclined, a seedling delivery platform (3) installed on the chassis (1) and located at the input end of the seedling separating mechanism (2), and a planting mechanism (4) installed on the chassis (1) and located below the seedling separating mechanism (2). The seedling delivery platform (3) is used to deliver seedlings to the seedling separating mechanism (2). The transplanting mechanism (4) is composed of several transplanting units, which are used to transplant the seedlings output from the end of the seedling separating mechanism (2). The adaptive adjustment device also includes a continuously variable transmission drive mechanism (5) for controlling the operation of the insertion mechanism (4). The continuously variable transmission drive mechanism (5) is composed of several drive units, each drive unit corresponding to one insertion unit, and the drive unit is connected to the corresponding insertion unit in a transmission manner. The adaptive adjustment device further includes an adaptive adjustment system (6), which includes: At least one seedling density sensing module (61) has a field of view covering a preset area upstream of the seedling delivery platform (3) and the seedling separating mechanism (2) for real-time acquisition of seedling quantity information characterizing the seedling distribution density in the area; A speed sensing module is used to obtain the real-time travel speed of the rice transplanter; A controller is connected to the seedling density sensing module (61), the speed sensing module, and the continuously variable transmission drive mechanism (5); the controller is configured to: Based on the real-time travel speed and a target plant spacing, the basic rotation speed required at the output end of the planting mechanism (4) is dynamically calculated; Based on the seedling quantity information, an overall seedling density index is generated, and the density index is compared with a preset standard density range to determine a compensation amount to compensate for the deviation in the grasping quantity. The base speed and the compensation amount are superimposed to calculate the target transmission ratio, and a corresponding control signal is output to the continuously variable transmission drive mechanism (5) so that the actual insertion frequency of the insertion unit is continuously adjusted, and finally adaptive compensation is achieved. When generating the overall seedling density index, the controller performs the following operations: Divide the image or point cloud data of the preset area into multiple grids; Based on the distance between each grid and the top of the seedling separating mechanism (2), a spatial weight coefficient is assigned to each grid, where the closer the distance, the higher the weight; Calculate the local density metric for each grid and remove anomalous grids caused by soil or water stains; The overall seedling density index is obtained by weighting the local density metrics of all effective grids according to their spatial weight coefficients.

2. The adaptive seedling density adjustment device for a rice transplanter according to claim 1, characterized in that: The seedling separating mechanism (2) includes a support frame (21), an inclined plate (22), a guide plate (23), and a seedling separating cover (24). The support frame (21) is fixedly connected to the chassis (1). The inclined plate (22) is fixedly connected to the support frame (21). The guide plate (23) is connected to the upper end of the inclined plate (22). The guide plate (23) is located below the output end of the seedling delivery platform (3). Several seedling separating covers (24) are connected to the inclined plate (22). A channel (25) for accommodating the downward sliding of seedlings is formed between the seedling separating covers (24) and the inclined plate (22). A baffle (26) perpendicular to the inclined plate (22) is provided at the lower end of the inclined plate (22). Several seedling taking ports (27) corresponding to the channel (25) are opened on the baffle (26). The seedling taking ports (27) are located below the corresponding channel (25).

3. The seedling density self-adaptive adjusting device for a rice transplanter according to claim 2, characterized in that: The seedling delivery platform (3) includes a belt conveyor (31), which is installed on both sides of the chassis (1) via a frame (32). The output end of the belt conveyor (31) is located above the guide plate (23), and the input end of the belt conveyor (31) extends to the rice transplanter. Several limiting strips (33) are fixed on the conveyor belt of the belt conveyor (31), and a conveying area (34) corresponding to the channel is formed between adjacent limiting strips (33).

4. The seedling density self-adaptive adjusting device for a rice transplanter according to claim 3, characterized in that: The planting unit includes two first bearing seats (41), one first drive shaft (42), one second bearing seat (43), one second drive shaft (44), two third bearing seats (45), one third drive shaft (46), a set of planting arms (47), and a set of seedling picking mechanism (48). The drive unit includes a continuously variable motor (51), a first sprocket (52), a second sprocket (53), a first chain (54), a third sprocket (55), a fourth sprocket (56), and a second chain (57); Two first bearing seats (41) are fixedly connected to the chassis (1), and the first drive shaft (42) is rotatably connected to the two first bearing seats (41) through bearings. The output end of the continuously variable motor (51) is connected to one end of the first drive shaft (42). Two second bearing seats (43) are fixedly connected to the chassis (1) and are close to the inclined plate (22). The second drive shaft (44) is rotatably connected to the two second bearing seats (43) through bearings. The first sprocket (52) is mounted on the first drive shaft (42), and the second sprocket (53) is mounted on the second drive shaft (44). The diameter of the second sprocket (53) is larger than the diameter of the first sprocket (52). The first sprocket (52) and the second sprocket (53) are connected by a first chain (54). Two third bearing seats (45) are installed at the lower end of the support frame (21), and the third drive shaft (46) is rotatably connected to the two third bearing seats (45) through bearings; a third sprocket (55) is installed at one end of the second drive shaft (44), and a fourth sprocket (56) is installed on the third drive shaft (46). The third sprocket (55) and the fourth sprocket (56) are connected by a second chain (57). The insertion arm (47) includes a hinge seat (471), a connecting rod (472), and an L-shaped lever (473) pivotally connected to the connecting rod. The hinge seat (471) is fixedly connected to the chassis (1). One end of the connecting rod (472) is pivotally connected to the hinge seat (471). One end of the lever (473) is pivotally connected to one end of the connecting rod (472). A pin is connected to one side of the second sprocket (53). The lever (473) is pivotally connected to the pin. A V-shaped opening (474) is provided at the end of the lever (473) away from the connecting rod (472). The chassis (1) is provided with several toothed openings (11) on the side facing the third drive shaft (46) to accommodate the lever (473) swinging up and down inside. The seedling picking mechanism (48) includes a cam disc (481), a seedling picking rod (482), a spring, a limiting rod (483), and a seedling picking claw (484). One side of the cam disc (481) is connected to the lower part of the support frame (21) by screws. The seedling picking rod (482) is fixedly connected to the third transmission shaft (46). The seedling picking rod (482) is located on one side of the cam disc (481). The seedling picking rod (482) and the cam disc (481) are located obliquely below the seedling picking opening (27). The seedling picking claw (484) is L-shaped, and its lower end is movably connected to the seedling picking rod (482). A spring is installed inside the seedling picking rod (482). The lower end of the seedling picking claw (484) is connected to the spring, and the upper end of the seedling picking claw (484) is connected to the seedling picking rod (482). A clamping part is formed to clamp the seedlings that fall from the seedling picking port (27); the limiting rod (483) is connected to the seedling picking claw (484), and the seedling picking rod (483) has a strip-shaped sliding hole (485) on its body. The limiting rod (483) is slidably disposed in the sliding hole (485); the inner wall of the cam disk (481) is convex, and one end of the limiting rod (483) is located in the cam disk (481), and the limiting rod (483) is pressed against the inner wall of the cam disk (481) by the action of a spring; the seedling picking rod (482) corresponds to the lever (473), and the seedling picking rod (482) is located on one side of the plane where the corresponding lever (473) is located. The seedlings grabbed by the seedling picking claw (484) are inserted into the soil by the lever (473).

5. The seedling density self-adaptive adjusting device for a rice transplanter according to claim 4, characterized in that: The seedling density sensing module (61) includes several visual sensors (611), which are installed above the belt conveyor (31) via a mounting frame (612). The visual sensors (611) correspond one-to-one with the conveying areas (34) between two adjacent limit bars (33), and the visual sensors (611) are located above the corresponding conveying areas (34). The seedling quantity information is an image of the preset area; the controller analyzes the texture features or color area ratio of the image through an image processing algorithm to obtain the local density metric value of each grid.

6. The seedling density self-adaptive adjusting device for a rice transplanter according to claim 5, characterized in that: The chassis (1) is connected to a protective cover (7). The first bearing seat (41), the first drive shaft (42), the continuously variable motor (51), the second bearing seat (43), and the second drive shaft (44) are all located inside the protective cover (7). The protective cover (7) has a first opening (71) on one side to accommodate the rotation of the lever (473) and a second opening (72) to accommodate the operation of the second chain (53).

7. The seedling density self-adaptive adjusting device for a rice transplanter according to claim 6, characterized in that: Both the chassis (1) and the mounting frame (612) are connected to a connecting seat (8), which is connected to the rice transplanter.

8. The seedling density self-adaptive adjusting device for a rice transplanter according to claim 7, characterized in that: The spatial weight coefficients are preset as follows: the grid weight corresponding to the first sub-region closest to the guide plate is 1.0, the grid weight corresponding to the second sub-region in the middle is 0.8, and the grid weight corresponding to the third sub-region furthest from the guide plate is 0.

5.

9. The seedling density self-adaptive adjusting device for a rice transplanter according to claim 8, wherein It also includes an input module connected to the controller for receiving the target plant spacing set by the operator.

10. A method for automatically adjusting the density of seedlings for a rice transplanter, implemented based on the device of claim 8, characterized in that, Includes the following steps: S1: Parameter initialization: Obtain the preset target in each delivery area and establish a model of the correspondence between seedling density level and compensation amount; S2: Real-time signal acquisition: Continuously acquire the real-time travel speed of the rice transplanter and the real-time seedling quantity information of the preset area at the end of the seedling delivery platform; S3: Base rotation speed calculation: Based on the real-time travel speed and target, the base rotation speed required for the implantation arm is calculated in real time; S4: Compensation Decision: Analyze the real-time seedling quantity information in each conveying area to generate an overall seedling density index. Specifically, this includes: dividing the preset area into multiple grids, and assigning a spatial weight coefficient to each grid based on the distance between each grid and the top of the seedling separating mechanism. The method for assigning the spatial weight coefficient to each grid is as follows: the preset area is divided into near zone, middle zone, and far zone along the seedling conveying direction. The weight of the near zone grid is set to 1.0, the weight of the middle zone grid is set to 0.8, and the weight of the far zone grid is set to 0.

5. Calculate the local density metric value for each grid and remove abnormal grids. Take a weighted average of the local density metrics values ​​of all valid grids to obtain the overall seedling density index. Compare the density index with the preset standard density range. When the density index is lower than the first threshold, generate a negative compensation amount. When the density index is higher than the second threshold, generate a positive compensation amount. S5: Target transmission ratio calculation and execution: The base speed is superimposed with the compensation amount to generate the target speed. Combined with the output speed of the continuously variable motor, the target transmission ratio that the continuously variable motor needs to achieve is calculated, and a control command is output to the continuously variable motor.

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