A fruit picking end effector of link and slot structure

Abstract

This invention discloses a pneumatic end effector for fruit picking with a linkage and sliding groove structure, comprising an actuator base, an actuator transmission structure, and a flexible end gripper. The actuator base includes an aluminum alloy structural component and a support rod, with the aluminum alloy structural component having an interface for connecting to the actuator transmission structure. The actuator transmission structure includes a rotating four-bar linkage and a gripping linkage and sliding groove mechanism, respectively realizing the two picking actions of rotation and gripping. The actuator transmission structure is connected between the actuator base and the flexible end gripper. The flexible end gripper includes a fixed base and a flexible clamping structure, which is fixedly connected to the gripping linkage and sliding groove mechanism. This invention achieves control of both gripping and twisting fruit picking actions within a limited space, and can grasp a wide range of fruit sizes, greatly improving the feasibility and success rate of fruit picking.

Description

Technical Field

[0001] This invention relates to the field of fruit picking end effector technology, and particularly to a fruit picking end effector with a connecting rod and slide groove structure. Background Technology

[0002] Fruit and vegetable harvesting robots are an important branch of agricultural robotics, aiming to automate fruit and vegetable harvesting. They can effectively address the current shortage of agricultural labor and high harvesting costs in various countries. The fruit-harvesting end effector is the core component of the harvesting robot, and the equipment is primarily used during the peak fruit harvest season for fruit picking.

[0003] The harvesting end effector is the core part of the entire design. A good harvesting end effector can greatly improve the harvesting success rate. Therefore, for fruit harvesting scenarios, it is necessary to design a fruit harvesting end effector that meets harvesting needs, is easy to use, has a simple structure, can harvest quickly, and is highly adaptable.

[0004] Existing harvesting devices generally only involve grasping the fruit, lacking the ability to perform other harvesting actions, and have a limited grasping diameter. Some harvesting actuators, such as those described in CN202210698406.6 and CN202210395678.9, add rotational freedom during the grasping process, allowing the claw to rotate itself to pick the fruit. While this structure is relatively easy to implement, its harvesting efficiency is limited. In reality, a person harvesting fruit involves twisting and pulling around the connection point between the stem and the fruit, a faster and more efficient harvesting action. However, existing harvesting devices rarely employ this method, resulting in poor harvesting efficiency. Summary of the Invention

[0005] In order to overcome the shortcomings of the existing technology, the present invention aims to provide a pneumatic end effector for fruit picking with a linkage slide structure. This actuator realizes the control of two picking actions, grasping and twisting the fruit, in a limited space. It can grasp a wide range of fruit sizes, which greatly improves the feasibility and success rate of fruit picking.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] A pneumatic end effector for fruit picking with a linkage and chute structure includes an actuator base, an actuator transmission structure, and a flexible end gripper.

[0008] The actuator base includes an aluminum alloy structural component and a support rod, and the aluminum alloy structural component is provided with an interface for connecting the actuator transmission structure.

[0009] The actuator transmission structure includes a rotating four-bar linkage and a gripping link slide mechanism, which respectively realize the two picking actions of rotation and gripping. The actuator transmission structure is connected between the actuator base and the end gripping flexible gripper. The end gripping flexible gripper includes a fixed base and a flexible clamping structure, which is fixedly connected to the gripping link slide mechanism.

[0010] Furthermore, the actuator base body includes aluminum alloy structural component one, aluminum alloy structural component two, and aluminum alloy structural component three. Aluminum alloy structural component one and aluminum alloy structural component three are arranged symmetrically on the left and right sides. Aluminum alloy structural component two is located in the lower part between aluminum alloy structural component one and aluminum alloy structural component three. The three aluminum alloy structural components are connected to form a U-shape. A support rod is connected between aluminum alloy structural component one and aluminum alloy structural component three to reinforce the entire actuator base.

[0011] The first and third aluminum alloy structural components are trapezoidal sheet metal with the same shape, while the second aluminum alloy structural component is a U-shaped sheet metal part with shorter lengths on both sides of the U-shape.

[0012] The aluminum alloy structural component 2 is provided with fixing holes for fixing aluminum alloy structural components 1 and 3. The plane in the middle of the U-shape is provided with mounting holes for fixing to a robotic arm or other equipment. The aluminum alloy structural components 1 and 3 are provided with symmetrical connecting rod hinge holes, and the hinge positions are provided with a side bearing of the same model as the side bearing. Among them, aluminum alloy structural component 1 is hinged to connecting rod 5 through female rivet 2 and to connecting rod 4 through female rivet 3. Aluminum alloy structural component 3 is hinged to connecting rod 2 through female rivet 1 and to connecting rod 2 through female rivet 3.

[0013] Support rod 1, support rod 2, support rod 3, and support rod 4 are provided between aluminum alloy component 1 and aluminum alloy component 3. Among them, support rod 1 serves as a rotation axis of the rotating four-bar linkage and is hinged to the corresponding rod using a flange bearing. Both ends of support rod 1 are connected to aluminum alloy component 1 and aluminum alloy component 3 through phase-locking rings of the same type to achieve axial fixation.

[0014] The remaining support rods 2, 3, and 4 are used to support the entire actuator base. The ends of each support rod are fixedly connected to aluminum alloy structural parts 1 and 3 by threaded bolts. The number of support rods 2, 3, and 4 can be appropriately reduced depending on the actual situation. The shaft corresponding to rivet 1 and the shaft corresponding to rivets 2 and 3 are the two rotation centers of the torsional action four-bar linkage.

[0015] Furthermore, the actuator transmission structure includes a rotary four-bar linkage for realizing torsional motion and a link slide mechanism for realizing grasping motion; the rotary four-bar linkage for realizing torsional motion includes link one, link two, link three, link four, link five, link six and actuator base, wherein link one and link five, link two and link four, link three and link six are rods of the same shape arranged symmetrically about aluminum alloy structural component one and aluminum alloy structural component three, improving the stability of the link movement; link three and link six are polygonal plate parts, the length of the longest side of the polygon is slightly larger than the maximum diameter of the fruit to be grasped;

[0016] Links 1 and 5 are identical in shape, both being V-shaped rod structures. Hinge holes are provided at both ends of the V-shape and at the bends. The bending angle can be adjusted according to actual needs. The hinge hole at the bend is used for hinged connection to the base in the aforementioned manner. Links 2 and 4 are identical in shape, both being straight groove-shaped rods. Hinge holes are provided at both ends. The bending angle can be adjusted according to actual needs. One end hole is used for hinged connection to the base in the aforementioned manner. Space is provided on links 3 and 6 to fix guide rail 1 and guide rail 2, and holes are also provided for hinged connection to shafts 1, 2, and 3. Link 3 is hinged to link 1 via shaft 1; link 6 is hinged to link 5 via shaft 1; link 3 is hinged to link 2 via shaft 2; and link 6 is hinged to link 4 via shaft 2.

[0017] The holes below connecting rod 1, connecting rod 2, connecting rod 4, and connecting rod 5 are all hinged to the corresponding holes on the actuator base; in addition, connecting rod 1 and connecting rod 5 are hinged through shaft 1 to ensure the concentricity of the corresponding rotation centers, and phase-locked rings are used on both sides of shaft 1 to achieve axial fixation; connecting rod 2 and connecting rod 4 are hinged through shaft 2, and phase-locked rings are used on both sides to achieve axial fixation.

[0018] The linear cylinder is connected to the rotary shaft via a fisheye bearing. The linear cylinder is fixedly connected to the drive connecting rod via a sheet metal mounting bracket. The linear cylinder, connected to the fisheye bearing, drives connecting rod one and connecting rod five via the drive shaft, thereby driving the four-bar linkage consisting of the base and connecting rod one, connecting rod two, connecting rod three, connecting rod four, connecting rod five, and connecting rod six to move and complete the torsional action. The linear cylinder is fixed at the front end of the cylinder body using a sheet metal mounting bracket.

[0019] Furthermore, based on the same linkage layout and cylinder drive principle, different dimensional parameters can be modified to obtain different torsional gripping effects and achieve the harvesting of different fruits.

[0020] Furthermore, the connecting rod slide mechanism realizes the torsional action. The connecting rod slide mechanism includes connecting rod three, connecting rod six, connecting rod seven, connecting rod eight, linear cylinder, fisheye bearing, gripper fixing seat, gripper fixing seat, slider one, slider two, guide rail one, and guide rail two.

[0021] The connecting rod seven is a V-shaped sheet metal component with a bending angle close to 180°. The specific bending angle is adjusted according to the actual calculated gripper stroke and distance. Hinge holes are provided on the short side and at the bend. The short side hinge hole is used for hinged connection with the linear cylinder, and the bend hinge hole is used for hinged connection with shaft three. The long side has a linear groove and bends. Connecting rod seven is hinged to connecting rods three and six via rotating shaft three. A retaining bearing is provided at the hinge point. The hinge position between connecting rods three and six differs from the hinge position with connecting rods five and four, located on the other side of the connecting rod, with its hinge hole directly below the guide rail mounting hole. Phase lock rings are fixedly connected to both ends of rotating shaft three for axial positioning between connecting rods three and six. Connecting rod seven is hinged to a fisheye bearing via bolts, and the fisheye bearing is fixedly connected to the linear cylinder.

[0022] Both the gripper fixing base and the gripper fixing base are rectangular frame structures with four mounting surfaces. One surface is used to mount the gripper, and a pair of opposite surfaces are used to mount the slider and the plug bolt, respectively. The gripper fixing base and the gripper fixing base are hinged together by the plug bolt, and a retaining bearing is provided at the hinge.

[0023] The connecting rod seven is provided with a sliding groove, and the plug bolt is inserted into the sliding groove. An axial retaining ring is provided between the connecting rod seven and the gripper fixing seat to achieve axial fixation. At the same time, a retaining bearing is provided to fix the connecting rod seven axially between the gripper fixing seat and the gripper fixing seat. During the movement of the connecting rod, the plug bolt moves in the groove, driving the gripper fixing seat and the gripper fixing seat to move.

[0024] The gripper fixing seat and the gripper fixing seat are respectively fixed on slider one and slider two. Slider one is connected to guide rail one and can move along a straight line along the guide rail. Slider two is connected to guide rail two and can move along guide rail two. Guide rail one is fixedly connected to connecting rod three by bolts, and the fixed position is on the other side of the hinge position of connecting rod and connecting rod five. Guide rail two is fixedly connected to connecting rod six by bolts, and the fixed position is directly opposite to guide rail one. Guide rail one and guide rail two are both fixed on one side between connecting rod three and connecting rod six.

[0025] The gripper fixing seat and the gripper fixing seat can move linearly along the guide rail 1 and guide rail 2 on the connecting rod 3 and the connecting rod 6; the linear cylinder and the connecting rod 8 are fixedly connected through the cylinder fixing seat, and the connecting rod 8 and the rotating shaft 2 are hinged through the flange bearing; the gripper fixing seat 234 is fixedly connected between the connecting rod 3 and the connecting rod 6 by bolts.

[0026] Furthermore, the range of movement of the gripper fixing seat and the gripper fixing seat on guide rail one and guide rail two can be calculated according to the schematic diagram and actual dimensions. By changing the length of the slot and the bending angle of the connecting rod seven, an appropriate stroke range can be adopted. The length limitation of the slot can be used to mechanically limit the sliding ends and prevent slider one and slider two from falling off guide rail one and guide rail two. The force of grasping the fruit is within a controllable range. Changing the output force of slider one on the linear cylinder can change the force of grasping the fruit.

[0027] Furthermore, the end-effector gripper includes gripper fixing printed component one, gripper fixing printed component two, gripper fixing printed component three, silicone substrate one, silicone substrate two, aluminum alloy frame three, and aluminum alloy frame four.

[0028] The first, second, and third gripper fixing printed parts are all trapezoidal printed parts, and their dimensions vary depending on the size of the gripper fixing seat they are fixed to. The first and second silicone substrates are irregularly shaped parts with the same shape to adapt to the shape of the fruit, and the internal groove design is used to adapt to the shape of the fruit.

[0029] The bottom of the gripper fixing printing component is fixedly connected to the gripper fixing seat, and the aluminum alloy frame three is fixedly connected to the gripper fixing printing component one by bolts.

[0030] The bottom of the second clamping printing component is fixedly connected to the clamping mounting base, and the bottom of the third clamping printing component is fixedly connected to the clamping mounting base. The fourth aluminum alloy frame is fixedly connected to the second and third clamping printing components by bolts.

[0031] The first silicone substrate is shaped to fit the fruit's shape and has a certain degree of flexibility. It comes into direct contact with the fruit, and its flexibility protects the fruit from damage during harvesting. The third and fourth aluminum alloy frames are embedded in the first and second silicone substrates, ensuring gripping rigidity and stability during harvesting.

[0032] In the above technical solution, the steps for the harvesting end effector to harvest fruit are as follows:

[0033] (1) In the initial state, both linear cylinders are in the retracted state, that is, the cylinder rod extension length is the shortest.

[0034] (2) Move the harvesting end effector to the fruit to be harvested, so that the fruit is between the two flexible grippers.

[0035] (3) Control the extension rod of the linear cylinder responsible for the grasping action to shorten the distance between the two flexible grippers and the silicone substrate, thereby clamping the fruit;

[0036] (4) After clamping the fruit, control the linear cylinder responsible for the twisting action to extend the rod, drive the gripper to twist and pick the fruit.

[0037] Compared with existing technologies, the effects and benefits of this invention are:

[0038] 1. This invention achieves the grasping and twisting action of fruit picking through a combination of multi-linkage, cylinder, slide, and guide rail slider. When picking fruit in an orchard, this actuator can be used for fruit picking. This picking actuator has a wide range of adaptability to different fruit sizes and can pick fruits of various sizes, while simultaneously performing both grasping and twisting picking actions.

[0039] 2. The picking actuator is driven by two linear cylinders to control the actions of grasping and twisting the fruit, keeping the picking action within a controllable range. With appropriate driving air pressure and buffer, the picking actuator can meet the actual picking requirements.

[0040] 3. Compared to similar harvesting end effectors, this end effector uses pneumatic drive to achieve both gripping and twisting harvesting actions, while the related linkages have a lighter mass. Using this actuator for fruit harvesting ensures a safe and reliable process. Attached Figure Description

[0041] Figure 1 This is an isometric view of the overall structure of the present invention.

[0042] Figure 2 This is a structural diagram of the actuator base of the present invention.

[0043] Figure 3 This is a structural diagram of the transmission structure of the present invention.

[0044] Figure 4 This is a diagram of the internal structure of the transmission structure of the present invention.

[0045] Figure 5 This is a diagram of the flexible gripper structure at the end of the present invention.

[0046] Figure 6 This is a schematic diagram of the torsion connecting rod cylinder drive of the present invention.

[0047] Figure 7 This is an external view of the connecting rod 217 of the present invention.

[0048] Figure 8 This is a schematic diagram of the linkage groove gripping mechanism of the present invention.

[0049] Figure 9 This is a schematic diagram of the harvesting action of the present invention.

[0050] In the picture:

[0051] 100. Actuator base body; 101. Aluminum alloy structural component II; 102. Aluminum alloy structural component; 103. Aluminum alloy structural component; 104. Side flange bearing; 105. Female and male rivets; 106. Support rod; 107. Side flange bearing; 108. Phase lock ring; 109. Support rod; 110. Support rod; 111. Support rod; 112. Female and male rivets; 113. Female and male rivets; 114. Female and male rivets;

[0052] 200. Actuator transmission structure; 201. Connecting rod; 202. Connecting rod; 203. Connecting rod; 204. Connecting rod; 205. Connecting rod; 206. Connecting rod; 207. Phase-locked ring; 208. Rotary shaft; 209. Linear cylinder; 210. Sheet metal mounting base; 211. Fish-eye bearing; 212. Drive connecting rod; 213. Rotary shaft; 214. Phase-locked ring; 215. Rotary shaft; 216. Phase-locked ring; 217. Connecting rod; 218. Plug bolt; 219. Rotary shaft; 220. Side bearing; 221. Plug bolt; 222. Side bearing; 223. Linear cylinder; 224. Connecting rod; 225. Sheet metal mounting base; 226. Fish-eye bearing; 227. Side bearing; 228. Gripper mounting base; 229. Gripper mounting base; 230. Slider; 231. Guide rail; 232. Slider; 233. Guide rail; 234. Gripper mounting base;

[0053] 300. End-effector flexible gripper; 301. Silicone substrate; 302. Silicone substrate; 303. Aluminum alloy frame; 304. Aluminum alloy frame; 305. Gripper fixing printed part; 306. Gripper fixing printed part; 307. Gripper fixing printed part; Detailed Implementation

[0054] The embodiments of the present invention are described in detail below. These embodiments are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0055] The overall structural isometric view of the invention is shown below. Figure 1 As shown, the entire assembly comprises three main parts: an actuator base 100, an actuator transmission structure 200, and a flexible end-effector gripper 300. The actuator base is the base of the integral linkage, its bottom fixedly connected to the harvesting robotic arm by bolts. Internal holes allow for hinge connections with the linkage. The actuator transmission structure is the core component of the entire harvesting end-effector, located between the actuator base and the flexible end-effector gripper. Its function is to realize the intended actions of the flexible end-effector gripper, including grasping and twisting the fruit. The flexible end-effector gripper is the part that actually contacts the fruit, fixedly connected to the output linkage of the actuator transmission structure. The gripper portion is made of flexible silicone, conforming to the shape of the fruit.

[0056] Figure 2This is a structural diagram of the actuator base of this invention. The three main aluminum plates, as shown in Figure 101, aluminum alloy structural component 102, and aluminum alloy structural component 103, are connected in a U-shape by bolts. Four sets of male and female rivets, namely 105, 112, 113, and 114, and shaft 106, are hinged to the connecting rod that realizes the torsional action. The hinged rotating part is equipped with a retaining bearing to ensure smooth rotation. Shaft 106 is axially fixed on both sides between aluminum alloy structural component 101 and aluminum alloy structural component 103 by phase-locked rings. The base is structurally reinforced by support rods 109, 110, and 111, which are fixedly connected to aluminum alloy structural component 101 and support rod 103 by threaded nuts.

[0057] Figure 3 This is a structural diagram of the transmission structure of the present invention. Connecting rods 201, 202, 203, 204, 205, 206, 212, 217, and 224 are all made of 4mm thick carbon fiber plates. Symmetrical edge bearings are provided at the hinge points to achieve axial positioning and rotational freedom. The symmetrical arrangement of the connecting rods improves the overall structural stability. Phase-locked loops 214 and 216 are used for axial fixation on both sides. The portion of the shaft between the connecting rods is axially positioned using bushings. A linear cylinder 209, connected to a fisheye bearing 211, drives connecting rods 201 and 205 via a drive shaft 208, thereby driving the base and the four-bar linkage consisting of connecting rods 201, 202, 203, 204, 205, and 206 to move, completing the torsional action. The linear cylinders are all fixed by using a sheet metal mounting bracket at the front end of the cylinder body.

[0058] Figure 4 This is a structural diagram of the internal structure of the transmission structure of the present invention. The diagram clearly shows the core components of the linkage and sliding mechanism responsible for the gripping action. These components mainly include link eight 224, linear cylinder 223 and fisheye bearing 226, link seven 217, gripper fixing seat 228, gripper fixing seat 229 and slider one 230, slider two 232, link one 201, link five 205 and gripper fixing seat 234 and guide rails one 231, 233 fixedly connected thereon. The linear cylinder 223 is the driving element; except for the fisheye bearing, all other hinge points use edge bearings. Rotary shaft two 213 and rotary shaft three 219 are aluminum alloy optical shafts, axially fixed using nylon bushings. The gripper fixing seat is made of aluminum alloy.

[0059] Figure 5This is a structural diagram of the flexible gripper at the end of the invention. The bottom gripper fixing printed parts 305, 306, and 307 are made of resin material. During assembly, gripper fixing printed part 305 is fixedly connected to gripper fixing seat 234 through a through hole at the bottom; gripper fixing printed part 306 is fixedly connected to gripper fixing seat 229 through a through hole at the bottom; and gripper fixing printed part 307 is fixedly connected to gripper fixing seat 228 through a through hole at the bottom. Aluminum alloy frames 303 and 304 can be cut from aluminum plates to create casting molds for silicone substrates 301 and 302. Aluminum alloy frames 303 and 304 are then embedded within these molds. Silicone substrates 301 and 302 are cast using these molds, and finally, the molds are removed. The obtained silicone substrate and aluminum alloy frame assembly are fixedly connected to the pre-reserved fixing holes of aluminum alloy frame three 303 and aluminum alloy frame four 304, and to the clamp fixing print part one 305, clamp fixing print part two 306, and clamp fixing print part three 307.

[0060] Figure 6 This is a schematic diagram of the torsion connecting rod cylinder drive of the present invention. Utilizing the characteristic that the stroke length is the distance between the maximum retraction and extension of the cylinder piston rod, the corresponding rod dimensions can be derived from the stroke size. For example, selecting a linear cylinder with a stroke of 50mm, the lengths of C1E1 and D1E1 in the diagram are... mm, and then calculate the dimensions of other rods based on the existing standard parts dimensions or design dimensions.

[0061] The entire torsional motion is driven by linear cylinder 209. The driving mechanism can also be viewed as a variable-length linkage mechanism, as shown in the schematic diagram below. Figure 6 As shown. The rotation axis corresponding to hinge point A1 is rotation axis 106; when the piston rod of linear cylinder 209 is retracted to its shortest length, the hinge point is C1; when the piston rod is extended to its longest length, the hinge point is D1, and the corresponding rotation axis is 208; the rotation axis corresponding to hinge point E1 is the rotation axis composed of rivet 112 and rivet 113. Linear cylinder 209 and rotation axis 208 are connected by fisheye bearing 211, and linear cylinder 209 is fixedly connected to drive connecting rod 212 by sheet metal mounting base 210. In the initial state, the upper planes of connecting rod 203 and connecting rod 206 are parallel to the large plane of aluminum alloy structural component 102. The torsional action can rotate the entire end gripper by nearly 90°, ensuring that the fruit can be picked.

[0062] Figure 7This is an external view of the connecting rod 217 of the present invention. The length of the slot is determined based on the schematic diagram and the calculation results of the gripping stroke. The slot allows the flexible gripper to reciprocate on the guide rail, and its length also enables self-locking of the gripper's stroke, preventing slider 230 and slider 232 from falling off guide rail 231 and guide rail 233. The bending angle can be changed according to actual needs.

[0063] Figure 8 This is a schematic diagram of the linkage and sliding groove gripping mechanism of this invention. The entire fruit-gripping structure and transmission are derived from this schematic diagram. Based on actual conditions, the neutral position is defined as EF vertically downwards, i.e., when the center line of the groove of link 7 217 is perpendicular to the arrangement direction of guide rails 1 231 and 233. A cylinder with a stroke of 30mm is selected. Based on the actual dimensions of each link, the angular range of CE rotating around the rotation center E is calculated, thereby calculating the angular range of EF rotating around the rotation center E, thus determining the slider's motion range and the guide rail length. The angle ∠CFE can be designed according to actual conditions to ensure optimal gripping stroke and transmission effect. Figure 9 This is a diagram illustrating the sequence of actions involved in picking fruit.

[0064] The schematic diagram of the linkage slide mechanism that realizes the torsional motion is as follows: Figure 8 As shown in the diagram, the rotation axis corresponding to hinge point A is rotation axis 213 (rotation axis two). The sliding pair between B and C corresponds to a linear cylinder. The rotation axis corresponding to hinge point C is a rotation axis composed of a stop bolt 218 and a fisheye bearing 226. The rotation axis corresponding to hinge point E is rotation axis 219 (rotation axis three). The fixed-length linear groove constraint corresponding to point F is composed of a stop bolt 221 and the groove of connecting rod 217 (connecting rod seven). The sliding pair corresponding to point F is a sliding pair composed of gripper fixing seat 228, gripper fixing seat 229, slider one 230, slider two 232, slide rail 231, and guide rail two 233. According to the schematic diagram, the movable components in this mechanism include connecting rod seven 217, connecting rod eight 224 and the cylinder body of cylinder 223, the piston rod of cylinder 223 and the fisheye bearing, and the gripper fixing seat 228, gripper fixing seat 229 and slider one 230, slider two 232 (connecting rod one 230, slider two 232). These components have a total of 12 degrees of freedom in the plane. The entire mechanism has 4 revolute joints, 1 prismatic joint, and 1 slot constraint, constraining a total of 11 degrees of freedom. Therefore, the linear cylinder 223 can drive the gripper fixing seats 228 and 229 to move linearly along connecting rods 3 and 6. When the piston rod of the linear cylinder 223 is retracted to its shortest length, the distance between the gripper fixing seats 228 and 229 and the gripper fixing seat 234 is the greatest; when the piston rod of the linear cylinder 223 is extended to its maximum stroke, the distance between the gripper fixing seats 228 and 229 and the gripper fixing seat 234 is the closest. The fruit-grabbing action is achieved during the extension of the piston rod of the linear cylinder 223.

[0065] This invention utilizes a linkage and sliding mechanism to grasp fruits, enabling the grasping of fruits of varying diameters. The structure is lightweight and space-efficient. The end-gripper stroke is theoretically calculated for maximum reliability. A four-bar linkage is used to twist the fruit, allowing it to be grasped and then removed from the stem. The entire end effector is driven by miniature cylinders, which are lightweight and have a wide adjustable output force range, allowing for different grasping and twisting forces to be set according to the grasping requirements of different fruits. Two miniature linear cylinders act as parts of a linkage, driving the grasping and twisting actions of the actuator. The entire fruit-picking end effector is lightweight and achieves control of both grasping and twisting actions within a limited space, grasping a wide range of fruit sizes and significantly improving the feasibility and success rate of fruit picking.

[0066] Working principle of the invention:

[0067] (1) In the initial state, the linear extension length of the linear cylinder is at its shortest. First, the end effector moves to the picked apple, so that the apple is between the flexible grippers formed by the flexible silicone substrate 1 301, the silicone substrate 2 302, the aluminum alloy frame 3 303, and the aluminum alloy frame 4 304, and the centers of the three are close to the same straight line.

[0068] (2) The linear cylinder 223 changes its linear extension length, thereby changing the linear distance between the two flexible grippers, so that the flexible grippers can clamp the apple and thus move the apple.

[0069] (3) After the grasping action is completed, the linear cylinder 223 remains in a self-locking state to ensure that the apple is always clamped, especially when twisting the fruit, to ensure stable grasping.

[0070] (4) The linear cylinder 209 changes its linear extension length, thereby changing the position of connecting rod 1 201 and 205. Through the four-bar linkage, connecting rod 3 203 and connecting rod 6 206 are driven to achieve a near 90° torsional motion, thereby achieving a 90° torsional motion on the apple.

[0071] (5) Finally, with a certain pulling action, remove the fruit, move the end effector to the fruit basket position, control the piston rod of linear cylinder 223 to retract to release the apple and make it fall into the fruit basket, and then control the piston rod of linear cylinder 209 to retract to restore the actuator to the initial state.

[0072] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the specific implementation of the present invention. Those skilled in the art can make other variations or modifications based on the above description. It is neither necessary nor possible to exhaustively describe all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A pneumatic end effector for fruit picking with a linkage and sliding groove structure, characterized in that, Includes actuator base, actuator transmission structure and end-effector flexible gripper; The actuator base includes an aluminum alloy structural component and a support rod, and the aluminum alloy structural component is provided with an interface for connecting the actuator transmission structure. The actuator transmission structure includes a rotary four-bar linkage and a linkage slide mechanism, which respectively realize the two picking actions of torsion and gripping. The actuator transmission structure is connected between the actuator base and the end gripping flexible gripper. The end gripping flexible gripper includes a fixed base and a flexible clamping structure, which is fixedly connected to the gripping linkage slide mechanism. The actuator transmission structure includes a rotary four-bar linkage for realizing torsional motion and a linkage slide mechanism for realizing grasping motion. The rotary four-bar linkage that realizes the torsional motion includes link one, link two, link three, link four, link five, link six, and actuator base. Link one and link five, link two and link four, and link three and link six are rods of the same shape arranged symmetrically about aluminum alloy structural component one and aluminum alloy structural component three. Link three and link six are polygonal sheet metal parts, and the length of the longest side of the polygon is slightly larger than the maximum diameter of the fruit to be grasped. Link 1 and Link 5 have the same shape, both being V-shaped rod structures. Hinge holes are provided at both ends of the V-shape and at the bends. The hinge hole at the bend is used for hinged connection with the actuator base in the manner described above. Link 2 and Link 4 have the same shape, both being straight groove rods. Hinge holes are provided at both ends, with one end used for hinged connection with the actuator base in the manner described above. Link 3 and Link 6 have spaces for fixing guide rail 1 and guide rail 2, and also have holes for hinged connection with shaft 1, shaft 2, and rotating shaft 3. Link 3 is hinged to Link 1 via shaft 1, Link 6 is hinged to Link 5 via shaft 1, Link 3 is hinged to Link 2 via shaft 2, and Link 6 is hinged to Link 4 via shaft 2. The connecting rod slide mechanism realizes the torsional action. The connecting rod slide mechanism includes connecting rod three, connecting rod six, connecting rod seven, connecting rod eight, linear cylinder two, fisheye bearing two, gripper fixing seat one, gripper fixing seat two, slider one, slider two, guide rail one, and guide rail two. The connecting rod seven is a V-shaped sheet metal component with a bending angle close to 180°. It has hinge holes on its short side and at the bend. The hinge hole on the short side is used to hinge with the second fisheye bearing, and the hinge hole at the bend is used to hinge with the third rotating shaft. The long side has a linear groove. Connecting rod seven is hinged to connecting rods three and six via the third rotating shaft. A retaining bearing is provided at the hinge point. The hinge position between connecting rods three and six differs from that between connecting rods five and four, located on the other side of connecting rod seven, with its hinge hole directly below the guide rail mounting hole. Phase lock rings are fixedly connected to both ends of the third rotating shaft for axial positioning between connecting rods three and six. Connecting rod seven is hinged to the second fisheye bearing via bolts, and the second fisheye bearing is fixedly connected to the second linear cylinder. Both gripper fixing base one and gripper fixing base two are rectangular frame structures with four mounting surfaces. One surface is used to mount the gripper, and a pair of opposite surfaces are used to mount the slider and the plug bolt, respectively. Gripper fixing base one and gripper fixing base two are hinged together by the plug bolt, and a retaining bearing is provided at the hinge.

2. The fruit-picking pneumatic end effector with a linkage slide structure according to claim 1, characterized in that, The actuator base includes aluminum alloy structural component one, aluminum alloy structural component two, and aluminum alloy structural component three. Aluminum alloy structural component one and aluminum alloy structural component three are arranged symmetrically on the left and right. Aluminum alloy structural component two is located in the lower part between aluminum alloy structural component one and aluminum alloy structural component three. The three aluminum alloy structural components are connected to form a U-shape. A support rod is connected between aluminum alloy structural component one and aluminum alloy structural component three to reinforce the entire actuator base.

3. The fruit-picking pneumatic end effector with a linkage slide structure according to claim 2, characterized in that, The aluminum alloy structural component one and aluminum alloy structural component three are trapezoidal sheet metal with the same shape, while aluminum alloy structural component two is a U-shaped sheet metal part, wherein the two sides of the U-shape are shorter. The aluminum alloy structural component 2 is provided with fixing holes for fixing aluminum alloy structural components 1 and 3. The plane in the middle of the U-shape is provided with mounting holes for fixing to a robotic arm or other equipment. The aluminum alloy structural components 1 and 3 are provided with symmetrical connecting rod hinge holes, and the hinge positions are provided with the same type of side bearing. Among them, aluminum alloy structural component 1 is hinged to connecting rod 5 through female rivet 2 and to connecting rod 4 through female rivet 4. Aluminum alloy structural component 3 is hinged to connecting rod 2 through female rivet 1 and to connecting rod 1 through female rivet 3.

4. The fruit-picking pneumatic end effector with a linkage slide structure according to claim 2, characterized in that, Support rod 1, support rod 2, support rod 3, and support rod 4 are provided between aluminum alloy component 1 and aluminum alloy component 3. Among them, support rod 1 serves as a rotation axis of the rotating four-bar linkage and is hinged to the corresponding rod using a flange bearing. Both ends of support rod 1 are connected to aluminum alloy component 1 and aluminum alloy component 3 through phase-locking rings of the same type to achieve axial fixation. The remaining support rods 2, 3, and 4 are used to support the entire actuator base. The ends of each support rod are fixedly connected to aluminum alloy structural parts 1 and 3 by threaded bolts. The shaft corresponding to rivet 1 and the shaft corresponding to rivets 2 and 3 are the two rotation centers of the rotating four-bar linkage.

5. The fruit-picking pneumatic end effector with a linkage slide structure according to claim 1, characterized in that, The holes below connecting rod 1, connecting rod 2, connecting rod 4, and connecting rod 5 are all hinged to the corresponding holes in the actuator base; connecting rod 1 and connecting rod 5 are hinged through shaft 1, and axial fixation is achieved on both sides of shaft 1 using phase-locked rings; connecting rod 2 and connecting rod 4 are hinged through shaft 2, and axial fixation is achieved on both sides using phase-locked rings. Linear cylinder 1 is connected to the rotary shaft via a fisheye bearing 1. Linear cylinder 1 is fixedly connected to the drive connecting rod via a sheet metal mounting bracket. Linear cylinder 1, connected to the fisheye bearing 1, drives connecting rod 1 and connecting rod 5 via the rotary shaft, thereby driving the four-bar linkage consisting of the base and connecting rods 1, 2, 3, 4, 5, and 6 to move and complete the torsional action. The linear cylinders are all fixed by using sheet metal mounting brackets at the front end of the cylinder body.

6. The fruit-picking pneumatic end effector with a linkage slide structure according to claim 1, characterized in that, The connecting rod seven is provided with a sliding groove, and the plug bolt is inserted into the sliding groove. An axial retaining ring is provided between the connecting rod seven and the first and second clamping jaw fixing seats to achieve axial fixation. At the same time, a retaining bearing is provided to fix the connecting rod seven axially between the first and second clamping jaw fixing seats. During the movement of the connecting rod, the plug bolt moves in the groove, driving the first and second clamping jaw fixing seats to move. The first and second gripper fixing seats are respectively fixed on the first and second sliders. The first slider is connected to the first guide rail and can move along the guide rail in a straight line. The second slider is connected to the second guide rail and can move along the second guide rail in a straight line. The first guide rail is fixedly connected to the third link by bolts, and the fixed position is on the other side of the hinge position of the sixth link and the fifth link. The second guide rail is fixedly connected to the sixth link by bolts, and the fixed position is directly opposite the first guide rail. The first and second guide rails are both fixed on one side between the third link and the sixth link. Linear cylinder two is fixedly connected to connecting rod eight through a cylinder mounting seat, and connecting rod eight is hinged to rotating shaft two through a flange bearing; gripper mounting seat three is fixedly connected between connecting rod three and connecting rod six by bolts.

7. A fruit-picking pneumatic end effector with a linkage slide structure according to claim 6, characterized in that, The end-effector flexible gripper includes gripper fixing printed component 1, gripper fixing printed component 2, gripper fixing printed component 3, silicone substrate 1, silicone substrate 2, aluminum alloy frame 3, and aluminum alloy frame 4. The gripper fixing printed part one, gripper fixing printed part two and gripper fixing printed part three are all trapezoidal printed parts. The silicone substrate one and silicone substrate two are irregular parts with the same shape adapted to the shape of the fruit. The internal groove design is used to adapt to the shape of the fruit. The bottom of the gripper fixing printing part one is fixedly connected to the gripper fixing seat three, and the aluminum alloy frame three is fixedly connected to the gripper fixing printing part one by bolts. The bottom of the second clamping printing component is fixedly connected to the second clamping base, and the bottom of the third clamping printing component is fixedly connected to the first clamping base. The fourth aluminum alloy frame is fixedly connected to the second and third clamping printing components by bolts.

8. A fruit-picking pneumatic end effector with a linkage slide structure according to claim 7, characterized in that, The silicone substrate one is shaped to fit the shape of the fruit; aluminum alloy frame three and aluminum alloy frame four are embedded in silicone substrate one and silicone substrate two.

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