A mango picking end effector integrated with clippers and shears mounted on a drone and a picking method

Abstract

The application discloses a mango picking end effector and picking method with a clamping and shearing integrated structure mounted on a UAV, which comprises a mounting rod, a shearing assembly, a clamping assembly and a single driving mechanism. The shearing assembly is arranged at the end of the mounting rod and comprises a fixed blade and a movable blade arranged in rotation relative to the fixed blade. The movable blade cooperates with the fixed blade to form a shearing position for cutting off the mango stem. The clamping assembly comprises a fixed clamp and a movable clamp arranged in motion relative to the fixed clamp. The fixed clamp is arranged on one side of the fixed blade, and the movable clamp is arranged on one side of the movable blade. The single driving mechanism is in transmission connection with the movable blade and is used for driving the movable blade to close or open relative to the fixed blade and driving the movable clamp to move towards the fixed clamp during the closing process of the movable blade. The application can reduce the number of driving elements and the mass of the end effector, improve the adaptability of the UAV, and reduce the risk of mango falling and stem damage after shearing.

Description

Technical Field

[0001] This invention relates to the field of agricultural harvesting technology, specifically to a mango harvesting end effector and harvesting method that integrates clamping and shearing functions and is mounted on a drone. Background Technology

[0002] Mango is one of my country's important tropical economic crops, widely cultivated in Guangdong, Guangxi, Hainan, Yunnan, and other regions. Mangoes are rich in nutrients and have high economic value. Because mangoes typically grow high in the tree canopy and are quite large, a certain length of the fruit stem must be retained during harvesting; therefore, manual harvesting is still the primary method.

[0003] During manual harvesting, fruit farmers typically use ladders, lifting platforms, and other equipment to climb into the tree canopy and use harvesting shears to cut the fruit stems. This method is not only labor-intensive and inefficient, but also poses safety hazards due to working at heights. Furthermore, the fruit is prone to collisions or falls during harvesting, causing mechanical damage and affecting fruit quality and economic benefits. In addition, mangoes secrete a latex after harvesting.

[0004] If the stem is cut too close to the fruit, it will contaminate the fruit and reduce its commercial value. Therefore, a certain length of stem must be retained.

[0005] With the continuous development of drone technology and intelligent agricultural equipment, drone-assisted fruit harvesting has gradually become an important direction for orchard mechanization. However, existing harvesting devices generally suffer from problems such as complex structure, heavy weight, insufficient coordination between clamping and shearing, and poor adaptability to drone payloads, making it difficult to meet the operational needs of efficient and low-damage mango harvesting.

[0006] Existing fruit-harvesting end effectors mostly employ a single shearing or simple clamping-shearing simultaneous structure. When harvesting mangoes, if only the stem is cut without retaining the side stem segment of the fruit, the fruit is prone to free fall after the stem is cut, causing bruising or harvesting failure. If a clamping mechanism directly holds the fruit body, it can easily cause compression damage to the peel, which is detrimental to maintaining the fruit's commercial quality. Therefore, a more suitable approach is to clamp the side stem segment of the fruit before and after stem cutting, allowing the fruit to be held by the end effector by retaining the stem segment.

[0007] On the other hand, existing clamping and shearing mechanisms typically synchronize the clamping and shearing actions rigidly, causing the clamping force to increase synchronously with the shearing force. When shearing the fruit stalk requires a large closing force, the clamping components may exert excessive pressure on the stalk, leading to scalding, breakage, or slippage. Conversely, if the clamping force is set too low, it becomes difficult to reliably hold the fruit after shearing. Therefore, how to achieve fruit stalk pre-clamping on the fruit side, stalk shearing on the tree side, and compliant clamping force limitation using a single drive source under the limited payload conditions of a drone is a key problem that mango drone harvesting end effectors need to solve. Summary of the Invention

[0008] To address the problems of existing mango picking devices, such as complex structure, numerous driving components, insufficient coordination between shearing and clamping, easy fruit drop after shearing, and poor adaptability to drones, this invention provides a mango picking end effector that integrates clamping and shearing and a picking method that can be mounted on a drone.

[0009] The objective of this invention is achieved through the following technical solution:

[0010] A mango-picking end effector with integrated clamping and shearing mechanism mounted on a drone includes a mounting rod, a shearing assembly, a clamping assembly, and a single drive mechanism.

[0011] The shearing assembly is located at the end of the mounting rod and includes a fixed blade and a movable blade that is rotatably disposed relative to the fixed blade. The movable blade cooperates with the fixed blade to form a shearing action position for cutting off the mango stem.

[0012] The clamping assembly includes a fixed clamp and a movable clamp that moves relative to the fixed clamp. The fixed clamp is disposed on one side of the fixed blade, and the movable clamp is disposed on one side of the movable blade. The movable clamp and the fixed clamp cooperate to form a clamping position for clamping the mango stem.

[0013] The clamping position is located along the axial direction of the mango stem on the side closer to the mango fruit at the shearing position, so that after the shearing component cuts the stem, the clamping component can clamp the stem segment connected to the mango fruit.

[0014] The single drive mechanism is connected to the moving blade transmission and is used to drive the moving blade to close or open relative to the fixed blade, and to drive the moving clamp to move towards the fixed clamp during the closing process of the moving blade, so as to achieve clamping and cutting of mango stem through the same drive source.

[0015] In a preferred embodiment of the present invention, the shearing action position forms a shearing line, and the clamping action position forms a clamping line;

[0016] Along the mango stem from the fruit towards the tree, the clamping line is located on the side of the shearing line closer to the fruit, and the shearing line is located on the side of the clamping line closer to the tree.

[0017] The shearing line and the clamping line have a predetermined distance, so that after the shearing component cuts off the fruit stem, the fruit stem segment held by the clamping component is still connected to the mango fruit.

[0018] Furthermore, the distance between the cutting line and the connecting end of the mango fruit is 30-50 mm, so that the harvested mango retains a predetermined length of fruit stem.

[0019] The clamping line is located between the shearing line and the end of the mango fruit, and the distance between the clamping line and the shearing line is 5 to 25 mm.

[0020] In a preferred embodiment of the present invention, the single drive mechanism includes a shear drive motor and a shear transmission assembly;

[0021] The shearing transmission assembly includes a lead screw, a lead screw nut, a linear transmission seat, a mounting sleeve, a U-shaped push-pull component, and a push-pull pin.

[0022] The lead screw is connected to the output shaft of the shear drive motor, the lead screw nut is fixedly mounted on the linear transmission seat, the linear transmission seat is slidably mounted on the mounting rod, and the mounting sleeve is fixedly connected to the linear transmission seat;

[0023] One end of the U-shaped push-pull component is fixedly connected to the mounting sleeve, and the other end is connected to the push-pull pin.

[0024] The moving blade is provided with a swing push-pull hole, and the push-pull pin passes through the swing push-pull hole to sequentially convert the rotational motion of the shearing drive motor into the axial movement of the linear transmission seat and the rotational closing motion of the moving blade.

[0025] Furthermore, two U-shaped push-pull components are provided, and the two U-shaped push-pull components are symmetrically arranged on both sides of the axis of the mounting sleeve;

[0026] The two U-shaped push-pull components are respectively connected to both ends of the push-pull pin shaft;

[0027] The fixed blade is provided with a push-pull clearance hole, and the push-pull pin passes through the push-pull clearance hole and the swing push-pull hole to avoid motion interference between the push-pull pin and the fixed blade during the rotation of the moving blade.

[0028] In a preferred embodiment of the present invention, the movable clamp is connected to the movable blade via a hinge shaft, and a floating connection mechanism is provided between the movable clamp and the movable blade;

[0029] The floating connection mechanism includes a floating gap and an elastic force limiting member, wherein the elastic force limiting member is disposed between the movable clamp and the movable blade;

[0030] After the movable clamp contacts and grips the mango stem, the movable blade continues to close relative to the fixed blade to complete the shearing action. The movable clamp can float and swing relative to the movable blade within the floating gap range, so that the clamping force of the clamping assembly is provided and limited by the elastic force limiting member. By setting a floating connection mechanism, a transmission path that separates the clamping force and shearing force is formed between the movable clamp and the movable blade, thereby avoiding the problem of the clamping force increasing synchronously with the shearing force. Therefore, it can not only ensure the reliable retention of the fruit stem, but also reduce the risk of fruit stem damage and clamping failure.

[0031] Furthermore, the elastic force limiting element is one of a reset torsion spring, a compression spring, a tension spring, or an elastic sheet;

[0032] The moving clamp tends to return to its initial opening position under the action of the elastic force limiting member;

[0033] When the movable clamp holds mango stems of different diameters, the movable clamp can adaptively swing around the hinge axis to adapt the clamping assembly to different stem diameters and reduce the risk of stem damage.

[0034] In a preferred embodiment of the present invention, the clamping surfaces of the movable clamp and / or the fixed clamp are provided with an elastic buffer layer;

[0035] The elastic buffer layer is one of polyurethane elastomer, rubber, silicone or flexible composite material;

[0036] The clamping surface is configured as an arc-shaped clamping surface, a grooved clamping surface, or a clamping surface with anti-slip texture to increase the contact area and friction between the clamping component and the mango stem.

[0037] A method for harvesting mangoes, comprising the following steps:

[0038] S1: Control the drone body to fly near the target mango, so that the end effector is close to the mango stem;

[0039] S2: Adjust the drone attitude and end effector position so that the cutting line is aligned with the fruit stem to be cut and the clamping line is located on the side of the cutting line closer to the mango fruit;

[0040] S3: Start the single drive mechanism, drive the moving blade to close in the direction of the fixed blade, and drive the moving clamp to move in the direction of the fixed clamp, so that the clamping component first clamps the side stem segment of the fruit at the clamping line;

[0041] S4: The single drive mechanism continues to drive the moving blade to close, so that the shearing assembly cuts off the fruit stalk near the side of the tree at the shearing line;

[0042] S5: After the fruit stalk is cut off, the clamping component maintains the clamping of the fruit stalk segment on the side, so that the harvested mango is suspended on the end effector.

[0043] S6: After the drone flies to the collection location, it controls the single drive mechanism to move in the opposite direction, causing the moving blade to open and the moving clamp to move away from the fixed clamp, releasing the clamping state and allowing the mango to fall into the collection container.

[0044] In a preferred embodiment of the present invention, a visual perception module is provided on the drone body, mounting rod, or end effector;

[0045] The drone body also includes a controller, which is communicatively connected to the visual perception module and is used to acquire information about the target mango fruit, the stem, the connection end between the stem and the fruit, and the direction of the stem toward the tree.

[0046] Furthermore, the controller is used to identify the fruit region, the fruit stalk region, and locate the connection end between the fruit stalk and the fruit based on the image information acquired by the visual perception module, and extract the central skeleton line of the fruit stalk region; taking the connection end between the fruit stalk and the fruit as the starting point, the cumulative length along the central skeleton line towards the tree body is used to determine the position to be cut within a range of 30 to 50 mm.

[0047] Furthermore, the controller establishes a virtual shearing domain model of the end effector. The virtual shearing domain model includes at least a shearing line, a clamping line, a shearable channel formed by the moving blade and the fixed blade, and a clampable channel formed by the moving clamp and the fixed clamp. The controller projects the virtual shearing domain model onto an image coordinate system, a camera coordinate system, or a point cloud coordinate system according to the calibration relationship between the visual perception module and the end effector to determine whether the central skeleton line enters the shearable clampable area.

[0048] Furthermore, the controller uses the shearing line and the clamping line as dual reference execution features. Based on the standard shearing point, the direction of the fruit stem, and the predetermined distance between the clamping line and the shearing line, it calculates the positional deviation between the shearing line and the standard shearing point, the attitude deviation of the shearing line relative to the direction of the fruit stem, and the positional constraint of the clamping line relative to the fruit stem segment on the side of the fruit. It then controls the movement of the UAV body or the end effector to align the shearing line with the standard shearing point, while simultaneously positioning the clamping line on the side of the shearing line closer to the mango fruit.

[0049] Furthermore, the controller generates a shearing accessibility evaluation value based on at least two of the following: visible length of the fruit stalk skeleton, effectiveness of the standard shearing point depth, alignment error of the shearing line, angular error of the shearing line relative to the direction of the fruit stalk, positional constraint of the clamping line relative to the fruit-side fruit stalk segment, and safe distance between the end effector and the mango fruit or tree branch; when the shearing accessibility evaluation value meets the preset conditions, the controller activates the single drive mechanism.

[0050] Furthermore, the controller is used to determine whether the clamping component has stably clamped the fruit stem segment on the side of the fruit based on the visual perception result and at least one of the following: shear drive motor current, encoder stroke, limit switch or position sensor signal; when the clamping stability condition is met, the controller continues to drive the moving blade to complete the shearing action; when the clamping stability condition is not met, the controller stops the shearing action or controls the drone to realign.

[0051] In a preferred embodiment of the present invention, step S2 includes:

[0052] S21, acquire image information and / or depth information of the target mango and its stem through the visual perception module;

[0053] S22, identify the target mango fruit area, the pedicel area, and the connection end between the pedicel and the fruit, and extract the central skeleton line of the pedicel area.

[0054] S23, along the central skeleton line, the cumulative length from the fruit side to the tree side is determined within the range of 30-50mm to determine the position to be cut;

[0055] S24, based on depth information and calibration relationship, transform the standard shearing point to the end effector coordinate system or project the virtual shearing domain model to the image coordinate system or point cloud coordinate system;

[0056] S25, visual servo adjustment is performed based on the positional deviation between the standard cutting point and the cutting line and the positional constraint of the clamping line relative to the fruit lateral stem segment.

[0057] S26, When the shear reachability evaluation meets the preset conditions, execute step S3.

[0058] Compared with the prior art, the present invention has the following advantages:

[0059] 1. By setting the moving clamp on the moving blade and the fixed clamp on the fixed blade, the clamping assembly and the shearing assembly form an integrated linkage structure. The overall structure is compact and has fewer parts, which helps to reduce the overall weight and volume of the end effector and improve the load adaptability of the UAV platform.

[0060] 2. This invention uses a single shearing drive motor as a power source. The shearing transmission component simultaneously drives the moving blade to rotate relative to the fixed blade. When the moving blade rotates, it drives the moving clamp to move synchronously, realizing the linkage and coordination of clamping and shearing actions. There is no need to set a separate drive source for the clamping component, which effectively reduces the number of drive components, reduces the overall energy consumption, and helps to extend the single flight time of the UAV.

[0061] 3. The invention has a simple overall structure, few driving components, light weight, and low energy consumption, making it particularly suitable for use on UAV platforms. It has good engineering application prospects and promotional value. Attached Figure Description

[0062] Figure 1 This is a three-dimensional structural diagram of the mango-picking drone of the present invention.

[0063] Figure 2 This is a schematic diagram of the mango-picking drone of the present invention picking mangoes.

[0064] Figure 3-4 These are three-dimensional structural diagrams of the mango picking end effector with integrated clamping and shearing mechanism of the present invention from two different perspectives.

[0065] Figure 5 This is a front view of the moving blade and the fixed blade of the mango picking end effector with integrated clamping and shearing according to the present invention.

[0066] Figure 6 This is a schematic diagram of the standard shearing point positioning process based on the arc length of the fruit stalk skeleton according to the present invention.

[0067] Figure 7 This is a schematic diagram of the virtual shearing domain model and dual-reference visual servo alignment of the present invention.

[0068] Figure 8 This is a schematic diagram of the clamp-then-shear triggering process of the vision-motor state fusion of the present invention. Detailed Implementation

[0069] To enable those skilled in the art to fully understand the technical solutions of the present invention, the present invention will be further described below in conjunction with embodiments and accompanying drawings, but the embodiments of the present invention are not limited thereto.

[0070] Example 1

[0071] Combination Figure 1 In this embodiment, the mango picking end effector with integrated clamping and shearing is mounted on the mango picking drone body 1. The mango picking end effector is located below, below front, or to the side front of the drone body 1 via a mounting rod 2 and a mounting frame 3. Specifically, the mounting rod 2 is a carbon fiber tube, a lightweight alloy tube, or a composite material tube. At least one of a vibration damping connector, a quick-release connector, or an attitude adjustment connector is provided between the mounting frame 3 and the drone body 1.

[0072] Furthermore, the UAV body 1 may include a flight controller, a power system, a power supply, and a remote or autonomous control module. The end effector may be electrically connected to the controller of the UAV body 1, enabling the controller to control the shear drive motor 8 to close in the forward direction, maintain clamping, and open in the reverse direction. The controller may also determine the closing state of the moving blade 5 based on the motor current, limit switch, encoder, or position sensor to achieve end-point protection and release control.

[0073] Furthermore, the mounting frame 3 can also be equipped with quick-release connectors to facilitate the maintenance, replacement, or transportation of the end effector; the mounting frame 3 can also be equipped with attitude adjustment connectors to adjust the installation angle of the end effector relative to the UAV body 1.

[0074] Combination Figure 2-5 The mango harvesting end effector includes a cutting assembly, a clamping assembly, and a single drive mechanism. The cutting assembly is located at the end of the mounting rod 2 and includes a fixed blade 4 and a movable blade 5 rotatably disposed relative to the fixed blade 4. The movable blade 5 cooperates with the fixed blade 4 to form a cutting position for cutting off the mango stem. The clamping assembly includes a fixed clamp 6 and a movable clamp 7 that moves relative to the fixed clamp 6. The fixed clamp 6 is disposed on one side of the fixed blade 4, and the movable clamp 7 is disposed on one side of the movable blade 5. The movable clamp 7 cooperates with the fixed clamp 6 to form a clamping position for clamping the mango stem. The clamping position is located along the axial direction of the mango stem on the side closer to the mango fruit at the cutting position, so that after the cutting assembly cuts off the stem, the clamping assembly can clamp the stem segment connected to the mango fruit side. The single drive mechanism is connected to the movable blade 5 and drives the movable blade 5 to close or open relative to the fixed blade 4. During the closing process of the movable blade 5, it drives the movable clamp 7 to move towards the fixed clamp 6, so as to achieve clamping and cutting of the mango stem through the same drive source.

[0075] Combination Figure 2-5 The shearing action position forms a shearing line, and the clamping action position forms a clamping line; along the direction from the fruit to the tree along the mango stalk, the clamping line is located on the side of the shearing line closer to the fruit, and the shearing line is located on the side of the clamping line closer to the tree; there is a predetermined distance between the shearing line and the clamping line, so that after the shearing component cuts the stalk, the stalk segment clamped by the clamping component is still connected to the mango fruit.

[0076] Furthermore, the distance between the shearing line and the connecting end of the mango fruit is 30-50 mm, so that the harvested mango retains a predetermined length of stem; the clamping line is located between the shearing line and the connecting end of the mango fruit, and the distance between the clamping line and the shearing line is 5-25 mm.

[0077] Combination Figure 3-5The single drive mechanism includes a shear drive motor 8 and a shear transmission assembly; the shear transmission assembly includes a lead screw 9, a lead screw nut 10, a linear transmission seat 11, a mounting sleeve 12, a U-shaped push-pull member 13, and a push-pull pin 14; the lead screw 9 is connected to the output shaft of the shear drive motor 8, the lead screw nut 10 is fixedly mounted on the linear transmission seat 11, the linear transmission seat 11 is slidably mounted on the mounting rod 2, and the mounting sleeve 12 is fixedly connected to the linear transmission seat 11; one end of the U-shaped push-pull member 13 is fixedly connected to the mounting sleeve 12, and the other end is connected to the push-pull pin 14; the moving blade 5 is provided with a swing push-pull hole 5-1, and the push-pull pin 14 passes through the swing push-pull hole 5-1 to sequentially convert the rotational motion of the shear drive motor 8 into the axial movement of the linear transmission seat 11 and the rotational closing motion of the moving blade 5.

[0078] Combination Figure 3-5 Two U-shaped push-pull members 13 are provided, and the two U-shaped push-pull members 13 are symmetrically arranged on both sides of the axis of the mounting sleeve 12; the two U-shaped push-pull members 13 are respectively connected to the two ends of the push-pull pin 14; the fixed blade 4 is provided with a push-pull clearance hole 4-1, and the push-pull pin 14 passes through the push-pull clearance hole 4-1 and the swing push-pull hole 5-1, so as to avoid motion interference between the push-pull pin 14 and the fixed blade 4 during the rotation of the moving blade 5.

[0079] Combination Figure 3-5 The movable clamp 7 is connected to the movable blade 5 via a hinge shaft, and a floating connection mechanism is provided between the movable clamp 7 and the movable blade 5. The floating connection mechanism includes a floating gap and an elastic force limiting member (not shown in the figure). The elastic force limiting member is disposed between the movable clamp 7 and the movable blade 5. When the movable clamp 7 contacts and clamps the mango stem with the fixed clamp 6, the movable blade 5 can continue to close relative to the fixed blade 4 to complete the cutting action. The movable clamp 7 can float and swing relative to the movable blade 5 within the floating gap range, so that the clamping force of the clamping assembly is provided and limited by the elastic force limiting member. By setting up a floating connection mechanism, a transmission path that separates the clamping force and the shearing force is formed between the movable clamp 7 and the movable blade 5, thereby avoiding the problem that the clamping force increases synchronously with the shearing force. Therefore, it can not only ensure the reliable retention of the fruit stem, but also reduce the risk of fruit stem damage and clamping failure.

[0080] Furthermore, the elastic force limiting element is one of a reset torsion spring, a compression spring, a tension spring, or an elastic sheet; the movable clamp 7 has a tendency to reset towards the initial open position under the action of the elastic force limiting element; when the movable clamp 7 clamps mango stems of different diameters, the movable clamp 7 can generate adaptive swing around the hinge axis so that the clamping assembly can adapt to mango stems of different diameters and reduce the risk of mango stem crushing.

[0081] Specifically, when the fruit stem diameter is small, the movable clamp directly clamps the fixed clamp; when the fruit stem diameter is large, the movable clamp rotates around the hinge point and compresses the return torsion spring, thus automatically adapting to fruit stems of different diameters. Furthermore, the clamping assembly is suitable for mango fruit stems with a diameter of 3–8 mm.

[0082] Furthermore, the clamping surfaces of the movable clamp 7 and / or the fixed clamp 6 are provided with an elastic buffer layer; the elastic buffer layer is one of polyurethane elastomer, rubber, silicone or flexible composite material; the clamping surface is set as an arc-shaped clamping surface, a grooved clamping surface or a clamping surface with anti-slip texture, so as to increase the contact area and friction between the clamping component and the mango stem.

[0083] Example 2

[0084] Combination Figure 2-5 The mango harvesting method in this embodiment includes the following steps:

[0085] S1: Control the drone body 1 to fly to the vicinity of the target mango, so that the end effector is close to the stem of the target mango.

[0086] S2: Adjust the drone's attitude and the position of the end effector so that the cutting line is aligned with the fruit stem to be cut, and the clamping line is located on the side of the cutting line closer to the mango fruit.

[0087] Furthermore, the cutting line is located within a range of 30 to 50 mm from the connecting end of the mango fruit, and more preferably at a standard cutting point approximately 40 mm from the connecting end of the mango fruit.

[0088] S3: Activate the single drive mechanism to drive the moving blade 5 to close towards the fixed blade 4, and drive the moving clamp 7 to move towards the fixed clamp 6, so that the clamping assembly first clamps the side stem segment of the fruit at the clamping line.

[0089] S4: The single drive mechanism continues to drive the moving blade 5 to close, so that the shearing assembly cuts off the fruit stalk near the side of the tree at the shearing line.

[0090] S5: After the fruit stalk is cut off, the clamping assembly holds the fruit stalk segment on the side, so that the harvested mango is suspended on the end effector.

[0091] S6: After the drone body 1 flies to the collection position, it controls the single drive mechanism to move in the opposite direction, causing the moving blade 5 to open and drive the moving clamp 7 away from the fixed clamp 6, releasing the clamping state and allowing the mango to fall into the collection container.

[0092] Furthermore, combined with Figure 6 Step S2 includes:

[0093] S21, acquire image information and / or depth information of the target mango and its stem through the visual perception module;

[0094] S22, identify the target mango fruit area, the pedicel area, and the connection end between the pedicel and the fruit, and extract the central skeleton line of the pedicel area.

[0095] S23, along the central skeleton line, the cumulative length from the fruit side to the tree side is determined within the range of 30-50mm to determine the position to be cut;

[0096] S24, based on depth information and calibration relationship, transform the standard shearing point to the end effector coordinate system or project the virtual shearing domain model to the image coordinate system or point cloud coordinate system;

[0097] S25, visual servo adjustment is performed based on the positional deviation between the standard cutting point and the cutting line and the positional constraint of the clamping line relative to the fruit lateral stem segment.

[0098] S26, When the shear reachability evaluation meets the preset conditions, execute step S3.

[0099] Example 3

[0100] In this embodiment, a visual perception module is provided on the drone body, mounting rod, or end effector; the drone body also includes a controller, which is communicatively connected to the visual perception module and is used to acquire information about the target mango fruit, the stem, the connection end between the stem and the fruit, and the direction of the stem toward the tree.

[0101] Furthermore, the controller is used to identify the fruit region, the fruit stalk region, and locate the connection end between the fruit stalk and the fruit based on the image information acquired by the visual perception module, and extract the central skeleton line of the fruit stalk region; taking the connection end between the fruit stalk and the fruit as the starting point, along the cumulative length of the central skeleton line towards the tree body, the position to be cut is determined within a range of 30 to 50 mm, preferably at a standard cutting point about 40 mm away from the connection end of the mango fruit.

[0102] Furthermore, the controller establishes a virtual shearing domain model of the end effector. The virtual shearing domain model includes at least a shearing line, a clamping line, a shearable channel formed by the moving blade and the fixed blade, and a clampable channel formed by the moving clamp and the fixed clamp. The controller projects the virtual shearing domain model onto an image coordinate system, a camera coordinate system, or a point cloud coordinate system according to the calibration relationship between the visual perception module and the end effector to determine whether the central skeleton line enters the shearable clampable area.

[0103] Furthermore, the controller uses the shearing line and clamping line as dual reference execution features. Based on the standard shearing point, the fruit stem direction, and the predetermined distance between the clamping line and the shearing line, it calculates the positional deviation of the shearing line from the standard shearing point, the attitude deviation of the shearing line relative to the fruit stem direction, and the positional constraint of the clamping line relative to the fruit-side fruit stem segment. It then controls the movement of the UAV body or end effector to align the shearing line with the standard shearing point while simultaneously positioning the clamping line on the side of the shearing line closer to the mango fruit. Figure 7 .

[0104] Furthermore, the controller generates a shearing accessibility evaluation value based on at least two of the following: visible length of the fruit stalk skeleton, effectiveness of the standard shearing point depth, alignment error of the shearing line, angular error of the shearing line relative to the direction of the fruit stalk, positional constraint of the clamping line relative to the fruit-side fruit stalk segment, and safe distance between the end effector and the mango fruit or tree branch; when the shearing accessibility evaluation value meets the preset conditions, the controller activates the single drive mechanism.

[0105] Specifically, the visible length of the fruit stalk skeleton is used to characterize the length of the fruit stalk centerline that the visual perception module can stably identify and use for positioning; when the visible length of the fruit stalk skeleton is insufficient, the controller has difficulty reliably determining the fruit stalk direction and the standard cutting point. The standard cutting point depth validity is used to characterize whether the standard cutting point has reliable depth information so that the standard cutting point can be converted from image coordinates to three-dimensional spatial coordinates. The cutting line alignment error is used to characterize the positional deviation between the end effector cutting line and the standard cutting point. The angle error of the cutting line relative to the fruit stalk direction is used to characterize the angle deviation between the end effector cutting posture and the local direction of the fruit stalk. The positional constraint of the clamping line relative to the fruit-side fruit stalk segment is used to determine whether the clamping line is located on the side of the cutting line closer to the mango fruit and falls on the fruit stalk segment that is still connected to the mango fruit after cutting. The safety distance is used to characterize whether a preset minimum gap is maintained between the end effector and the mango fruit or tree branch. The controller generates a cutting accessibility evaluation value based on at least two of the above parameters, and determines whether to activate a single drive mechanism to perform clamping and cutting actions based on the cutting accessibility evaluation value.

[0106] Furthermore, the controller is used to determine whether the clamping component has stably clamped the fruit stem segment on the side of the fruit based on the visual perception result and at least one of the following: shear drive motor current, encoder stroke, limit switch or position sensor signal; when the clamping stability condition is met, the controller continues to drive the moving blade to complete the shearing action; when the clamping stability condition is not met, the controller stops the shearing action or controls the drone to realign.

[0107] The above are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above content. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A mango-picking end effector with integrated clamping and shearing mechanism mounted on a drone, characterized in that, Includes mounting rod, shearing assembly, clamping assembly, and single drive mechanism; The shearing assembly is located at the end of the mounting rod and includes a fixed blade and a movable blade that is rotatably disposed relative to the fixed blade. The movable blade cooperates with the fixed blade to form a shearing action position for cutting off the mango stem. The clamping assembly includes a fixed clamp and a movable clamp that moves relative to the fixed clamp. The fixed clamp is disposed on one side of the fixed blade, and the movable clamp is disposed on one side of the movable blade. The movable clamp and the fixed clamp cooperate to form a clamping position for clamping the mango stem. The clamping position is located along the axial direction of the mango stem on the side closer to the mango fruit at the shearing position, so that after the shearing component cuts the stem, the clamping component can clamp the stem segment connected to the mango fruit. The single drive mechanism is connected to the moving blade transmission and is used to drive the moving blade to close or open relative to the fixed blade, and to drive the moving clamp to move towards the fixed clamp during the closing process of the moving blade, so as to achieve clamping and cutting of mango stem through the same drive source.

2. The mango picking end effector with integrated clamping and shearing mechanism mounted on a drone as described in claim 1, characterized in that, The shearing action position forms a shearing line, and the clamping action position forms a clamping line; Along the mango stem from the fruit towards the tree, the clamping line is located on the side of the shearing line closer to the fruit, and the shearing line is located on the side of the clamping line closer to the tree. The shearing line and the clamping line have a predetermined distance, so that after the shearing component cuts off the fruit stem, the fruit stem segment held by the clamping component is still connected to the mango fruit. The distance between the cutting line and the connecting end of the mango fruit is 30-50 mm, so that the harvested mango retains a predetermined length of fruit stem. The clamping line is located between the shearing line and the end of the mango fruit, and the distance between the clamping line and the shearing line is 5 to 25 mm.

3. The mango picking end effector with integrated clamping and shearing mechanism mounted on a drone according to claim 1, characterized in that, The single drive mechanism includes a shear drive motor and a shear transmission assembly; The shearing transmission assembly includes a lead screw, a lead screw nut, a linear transmission seat, a mounting sleeve, a U-shaped push-pull component, and a push-pull pin. The lead screw is connected to the output shaft of the shear drive motor, the lead screw nut is fixedly mounted on the linear transmission seat, the linear transmission seat is slidably mounted on the mounting rod, and the mounting sleeve is fixedly connected to the linear transmission seat; One end of the U-shaped push-pull component is fixedly connected to the mounting sleeve, and the other end is connected to the push-pull pin. The moving blade is provided with a swing push-pull hole, and the push-pull pin passes through the swing push-pull hole to convert the rotational motion of the shearing drive motor into the axial movement of the linear transmission seat and the rotational closing motion of the moving blade in sequence. Two U-shaped push-pull components are provided, and the two U-shaped push-pull components are symmetrically arranged on both sides of the axis of the mounting sleeve; the two U-shaped push-pull components are respectively connected to both ends of the push-pull pin. The fixed blade is provided with a push-pull clearance hole, and the push-pull pin passes through the push-pull clearance hole and the swing push-pull hole to avoid motion interference between the push-pull pin and the fixed blade during the rotation of the moving blade.

4. The mango picking end effector with integrated clamping and shearing mechanism mounted on a drone according to claim 3, characterized in that, The movable clamp is connected to the movable blade via a hinge shaft, and a floating connection mechanism is provided between the movable clamp and the movable blade; The floating connection mechanism includes a floating gap and an elastic force limiting member, wherein the elastic force limiting member is disposed between the movable clamp and the movable blade; After the movable clamp contacts the fixed clamp and clamps the mango stem, the movable blade can continue to close relative to the fixed blade to complete the cutting action. The movable clamp can float and swing relative to the movable blade within the floating gap range, so that the clamping force of the clamping assembly is provided and limited by the elastic force limiting member.

5. A mango harvesting method using the mango harvesting end effector integrated with a clamp and shear unit mounted on a drone as described in any one of claims 1-4, characterized in that, Includes the following steps: S1: Control the drone body to fly near the target mango, so that the end effector is close to the mango stem; S2: Adjust the drone attitude and end effector position so that the cutting line is aligned with the fruit stem to be cut and the clamping line is located on the side of the cutting line closer to the mango fruit; S3: Start the single drive mechanism, drive the moving blade to close in the direction of the fixed blade, and drive the moving clamp to move in the direction of the fixed clamp, so that the clamping component first clamps the side stem segment of the fruit at the clamping line; S4: The single drive mechanism continues to drive the moving blade to close, so that the shearing assembly cuts off the fruit stalk near the side of the tree at the shearing line; S5: After the fruit stalk is cut off, the clamping component maintains the clamping of the fruit stalk segment on the side, so that the harvested mango is suspended on the end effector. S6: After the drone flies to the collection location, it controls the single drive mechanism to move in the opposite direction, causing the moving blade to open and the moving clamp to move away from the fixed clamp, releasing the clamping state and allowing the mango to fall into the collection container.

6. The mango harvesting method according to claim 5, characterized in that, The drone body, mounting rod, or end effector is equipped with a visual perception module. The drone body also includes a controller, which is communicatively connected to the visual perception module and is used to acquire information about the target mango fruit, the stem, the connection end between the stem and the fruit, and the direction of the stem toward the tree.

7. The mango harvesting method according to claim 6, characterized in that, The controller is used to identify the fruit region, the fruit stalk region, and locate the connection end between the fruit stalk and the fruit based on the image information acquired by the visual perception module, and to extract the central skeleton line of the fruit stalk region; taking the connection end between the fruit stalk and the fruit as the starting point, the controller determines the position to be cut within a range of 30 to 50 mm along the cumulative length of the central skeleton line toward the tree body.

8. The mango harvesting method according to claim 6, characterized in that, The controller establishes a virtual shearing domain model of the end effector. The virtual shearing domain model includes at least a shearing line, a clamping line, a shearable channel formed by the moving blade and the fixed blade, and a clampable channel formed by the moving clamp and the fixed clamp. The controller projects the virtual shearing domain model onto the image coordinate system, camera coordinate system, or point cloud coordinate system based on the calibration relationship between the visual perception module and the end effector, in order to determine whether the central skeleton line enters the shearable area. The controller uses the shear line and clamping line as dual reference execution features. Based on the standard shear point, the direction of the fruit stem, and the predetermined distance between the clamping line and the shear line, it calculates the positional deviation between the shear line and the standard shear point, the attitude deviation of the shear line relative to the direction of the fruit stem, and the positional constraint of the clamping line relative to the fruit stem segment on the side of the fruit. It then controls the movement of the UAV body or end effector to align the shear line with the standard shear point while positioning the clamping line on the side of the shear line closer to the mango fruit.

9. The mango harvesting method according to claim 8, characterized in that, The controller generates a shearing accessibility evaluation value based on at least two of the following: visible length of the fruit stalk skeleton, effectiveness of the standard shearing point depth, alignment error of the shearing line, angular error of the shearing line relative to the direction of the fruit stalk, positional constraint of the clamping line relative to the fruit stalk segment on the side of the fruit, and safe distance between the end effector and the mango fruit or tree branch; when the shearing accessibility evaluation value meets the preset conditions, the controller activates the single drive mechanism.

10. The mango harvesting method according to claim 5, characterized in that, Step S2 includes: S21, acquire image information and / or depth information of the target mango and its stem through the visual perception module; S22, identify the target mango fruit area, the pedicel area, and the connection end between the pedicel and the fruit, and extract the central skeleton line of the pedicel area. S23, along the central skeleton line, the cumulative length from the fruit side to the tree side is determined within a range of 30-50mm to determine the position to be cut; S24, based on depth information and calibration relationship, transform the standard shearing point to the end effector coordinate system or project the virtual shearing domain model to the image coordinate system or point cloud coordinate system; S25, visual servo adjustment is performed based on the positional deviation between the standard cutting point and the cutting line and the positional constraint of the clamping line relative to the fruit lateral stem segment. S26, When the shear reachability evaluation meets the preset conditions, execute step S3.

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