Intelligent three-claw picking executor with touch force perception

Abstract

The present application belongs to the technical field of agricultural robots and intelligent picking equipment, and particularly relates to an intelligent three-claw picking actuator with touch force perception, comprising a wrist module, a knuckle module rotatably arranged at the upper end of the wrist module, the knuckle module being arranged with three knuckles and being distributed along the upper end of the wrist module, and a perception module fixedly connected to the clamping side of the knuckle module; the knuckle module comprises a first speed reducer, a first knuckle, a second speed reducer, a knuckle cover plate, a second knuckle, a third speed reducer, a fixed cover plate and a third knuckle, the output end of the first speed reducer is fixedly arranged at the outer edge of the wrist module, the inner end of one end of the first knuckle is fixedly connected with the first speed reducer, and the second speed reducer is fixedly connected with the inner end of the other end of the first knuckle. The present application can realize adaptive grasping and force feedback and improve picking stability through multi-joint independent driving, three-dimensional force and touch perception integration and wrist radial sliding compliant structure.

Description

Technical Field

[0001] This invention belongs to the field of agricultural robots and intelligent harvesting equipment technology, specifically relating to an intelligent three-claw harvesting actuator with tactile perception. Background Technology

[0002] With the development of modern agricultural automation, fruit and vegetable harvesting robots are playing an increasingly important role in improving harvesting efficiency and reducing labor costs. Fruits, due to their irregular shapes and varying sizes during growth, and their soft, easily damaged skin, place higher demands on the structural flexibility and gripping force control precision of robotic arms.

[0003] Existing fruit and vegetable harvesting robots mostly adopt pneumatic drive or single-motor linkage transmission structure. Their advantages are simple control and lightweight structure, but they have the following disadvantages: (1) Lack of real-time perception of three-dimensional forces in space during the grasping process makes it difficult to accurately determine whether the fruit is being stably held; (2) The fingertips do not integrate a tactile detection unit, so they cannot detect the minute changes in contact force between the fingertips and the fruit, which can easily lead to the fruit peel being crushed or slipping off; (3) The drives of each finger of the robotic arm are coupled to each other, resulting in insufficient flexibility and difficulty in adapting to the surface morphology of different fruits.

[0004] Existing technical solutions, such as CN120002696B, disclose a dexterous hand thumb structure. This structure forms a crank-slider mechanism through a lateral swing assembly, a knuckle, a linkage assembly, a first drive assembly, and a second drive assembly. This mechanism can drive the knuckle to rotate around a second axis to achieve knuckle bending. Simultaneously, under the drive of the second drive assembly, the knuckle can rotate around a first axis to achieve lateral swing. This solution uses at least four linkages that can rotate around axes in at least three directions, achieving decoupling of bending and lateral swing motions. It also eliminates the need for bulky gear transmissions, reducing the size of the dexterous hand fingers. However, this structure mainly relies on linkage transmissions to achieve joint movement, resulting in a relatively complex overall structure with a large number of parts, making it inconvenient for installation and maintenance. Furthermore, CN120715931A discloses a four-claw robotic hand. This design integrates rotation and retraction mechanisms within the fingertips, achieving a compact layout through an implicit transmission design, effectively reducing the overall size of the robotic hand and enabling it to perform grasping operations in confined spaces. This design employs a symmetrically distributed four-claw structure, enabling stable gripping of target objects. However, the grasping action of this robotic hand is relatively simple, and the movements of each finger joint are somewhat coupled, making it difficult to adaptively adjust to the irregular surface morphology of the fruit. Simultaneously, this design lacks a multi-dimensional force sensor at the wrist, failing to achieve real-time perception and force feedback control of three-dimensional forces during grasping. Additionally, although the fingertips have contact structures, they lack integrated tactile detection units, making it impossible to detect minute changes in contact force between the fingertips and the fruit, potentially leading to bruising or slippage when grasping soft and fragile fruits and vegetables. Summary of the Invention

[0005] The purpose of this invention is to provide an intelligent three-claw picking actuator with tactile perception, which can achieve adaptive grasping and force feedback through multi-joint independent drive, three-dimensional force and tactile perception integration and a radial sliding compliant structure of the wrist, thereby improving picking stability and safety.

[0006] The specific technical solution adopted by this invention is as follows: A smart three-claw picking actuator with tactile perception includes a wrist module, a knuckle module rotatably mounted on the upper end of the wrist module, three knuckle modules are mounted on the upper end of the wrist module and arranged at 120 degrees along the upper end of the wrist module, and a sensing module is fixedly connected to the clamping side of the knuckle module. The knuckle module includes a first geared motor, a first knuckle, a second geared motor, a knuckle cover, a second knuckle, a third geared motor, a fixed cover, and a third knuckle. The output end of the first geared motor is fixedly disposed on the outer edge of the wrist module. The interior of one end of the first knuckle is fixedly connected to the first geared motor. The second geared motor is fixedly connected to the interior of the other end of the first knuckle. The knuckle cover is fixedly disposed on one side of the first knuckle to confine the first and second geared motors inside the first knuckle. One end of the second knuckle is fixedly connected to the output end of the second geared motor. The third geared motor is fixedly disposed inside the second knuckle. The fixed cover is fixedly connected to the second knuckle. The third knuckle is fixedly connected to the output end of the third geared motor.

[0007] In a preferred embodiment, the wrist module includes a three-dimensional sensor, a mounting body, a sliding seat, a fixing plate, a connecting ring, and a compression spring. One end of the three-dimensional sensor is connected to the corresponding end flange of the robotic arm. The mounting body is fixedly disposed at the other end of the three-dimensional sensor. One end of the sliding seat is fixedly connected to a first reduction motor. Multiple sliding seats are arranged in a ring at the other end of the mounting body. The sliding seats are slidably disposed inside the mounting body. The fixing plate is fixedly disposed at the other end of the mounting body to limit the sliding seats inside the mounting body. The connecting ring is disposed inside each sliding seat, connecting the sliding seats into a single unit. The compression spring is disposed between adjacent sliding seats and is sleeved on the outer edge of the connecting ring.

[0008] In a preferred embodiment, the mounting body, the first phalanx, the second phalanx, and the third phalanx are provided with L-shaped mounting grooves inside, and the interior of the mounting grooves mates with the output shafts of the first geared motor, the second geared motor, and the third geared motor.

[0009] In a preferred embodiment, the output shafts of the first geared motor, the second geared motor, and the third geared motor are provided with limiting surfaces, which cooperate with fixing bolts that pass through the mounting groove.

[0010] In a preferred embodiment, the three-dimensional sensor includes a base, a sensitive beam, and a guide column. One end of the base is fixedly connected to the interior of the mounting body, four sets of sensitive beams are fixedly connected to the outer edge of one end of the base, and the other end of the sensitive beam is fixedly connected to the guide column.

[0011] In a preferred embodiment, the sensitive beam is composed of a vertical floating beam and a horizontal floating beam, and the angle between the vertical floating beam and the horizontal floating beam is 135 degrees. Strain gauges are attached to the surfaces of the vertical floating beam and the horizontal floating beam to form a Wheatstone full-bridge circuit for measuring X, Y, and Z forces.

[0012] In a preferred embodiment, the sensing module includes a first mounting bracket, a second mounting bracket, a fingertip mounting bracket, and a contact pad. One end of the first mounting bracket is fixedly connected to a first phalanx by a bolt, one end of the second mounting bracket is fixedly connected to a second phalanx by a bolt, one end of the fingertip mounting bracket is fixedly connected to a third phalanx by a bolt, and the contact pad is disposed at the other end of the fingertip mounting bracket of the first mounting bracket and the second mounting bracket.

[0013] In a preferred embodiment, the first mounting bracket, the second mounting bracket, the fingertip mounting bracket, and the contact pad are provided with a parallel beam flexible structure, and strain gauges are attached to the surface of the parallel beam structure.

[0014] In a preferred embodiment, the contact surface of the contact pad is provided with honeycomb-shaped slots.

[0015] In a preferred embodiment, the mounting body has an annular guide groove inside, and the annular guide groove is divided into three sections, with a corresponding sliding seat slidably disposed inside each section of the guide groove.

[0016] The technical effects achieved by this invention are as follows: This invention employs a three-stage geared motor independent drive and direct transmission design. By setting geared motors inside the first, second, and third phalanges, it achieves multi-joint coordinated control and rapid response of the phalanges, enabling the actuator to adaptively adjust the grasping posture according to the fruit shape. This significantly improves the adaptability to fruits of different shapes and sizes and the grasping success rate. At the same time, the modular packaging structure integrates each drive unit independently inside the phalanges, simplifying the assembly process and facilitating individual disassembly and replacement, thus greatly reducing maintenance costs and difficulty. This invention employs a radially sliding wrist structure and a compression spring buffer mechanism. By setting sliding seats, connecting rings, and compression springs inside the mounting body, each finger module can automatically adjust its gripping position according to the actual shape and size of the fruit during the gripping process, achieving passive adaptive envelope of the fruit. The compression springs can effectively absorb and buffer energy when gripping impact or vibration occurs, avoiding damage to the fruit skin caused by rigid impact. The connecting rings connect the sliding seats into one unit, ensuring that the three finger modules always maintain synchronous movement during radial sliding, so that the gripping center always coincides with the geometric center of the actuator, avoiding gripping deviation or fruit slippage caused by asynchronous sliding of a single finger. This invention employs an integral semi-octagonal ring structure three-dimensional force sensor and a parallel beam tactile sensing structure. By dividing the sensitive beam into a vertical floating beam and a horizontal floating beam, and attaching strain gauges to its surface to form a Wheatstone full-bridge circuit, high-precision decoupled measurement and real-time feedback of the grasping force are achieved, providing accurate signal input for force-position hybrid control. A flexible parallel beam structure is set between the first mounting frame, the second mounting frame, the fingertip mounting frame, and the contact pad, enabling the actuator to sense the contact force in real time during the grasping process. This effectively avoids damage to the fruit skin due to excessive grasping force, ensuring the safety and non-destructive nature of the harvesting process. The honeycomb-shaped slots on the contact pad significantly reduce the rigidity of the contact area while maintaining the overall structural strength of the pad, increasing the coefficient of friction on the contact surface and achieving adaptive fitting to irregular surfaces, effectively preventing fruit slippage. Attached Figure Description

[0017] Figure 1 This is an overall schematic diagram of an embodiment of the present invention; Figure 2 This is a schematic diagram of the overall opening of an embodiment of the present invention; Figure 3 This is an exploded view of an embodiment of the present invention; Figure 4This is an exploded view of the wrist module according to an embodiment of the present invention; Figure 5 This is an exploded view of the knuckle module and sensing module according to an embodiment of the present invention; Figure 6 This is a side view of the knuckle module and sensing module according to an embodiment of the present invention; Figure 7 This is a schematic diagram of the structure of a three-dimensional force sensor according to an embodiment of the present invention; Figure 8 This is a top view of a three-dimensional sensor according to an embodiment of the present invention; Figure 9 This is a bottom view of a three-dimensional sensor according to an embodiment of the present invention; Figure 10 This is an exploded view of the sensing module according to an embodiment of the present invention; Figure 11 This is an embodiment of the present invention. Figure 10 Schematic diagram at point A in the middle; Figure 12 This is a circuit diagram of the strain gauge group for measuring force in the X direction according to an embodiment of the present invention; Figure 13 This is a circuit diagram of the strain gauge group for measuring force in the Y direction according to an embodiment of the present invention; Figure 14 This is a circuit diagram of the strain gauge group for measuring force in the Z direction, according to an embodiment of the present invention.

[0018] The attached diagram lists the components represented by each number as follows: 1. Wrist Module; 101. 3D Sensor; 1011. Base; 1012. Sensing Beam; 1013. Guide Column; 102. Mounting Body; 103. Sliding Seat; 104. Fixing Plate; 105. Connecting Ring; 106. Compression Spring; 2. Knuckle Module; 201. First Gear Motor; 202. First Knuckle; 203. Second Gear Motor; 204. Knuckle Cover Plate; 205. Second Knuckle; 206. Third Gear Motor; 207. Fixing Cover Plate; 208. Third Knuckle; 3. Sensing Module; 301. First Mounting Frame; 302. Second Mounting Frame; 303. Fingertip Mounting Frame; 304. Contact Gasket; 2121. Vertical Floating Beam; 2122. Horizontal Floating Beam. Detailed Implementation

[0019] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0020] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0021] Secondly, the term "an embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in a preferred embodiment" appearing in different places throughout this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that mutually excludes other embodiments.

[0022] Secondly, the present invention is described in detail with reference to the schematic diagrams. When detailing the embodiments of the present invention, for ease of explanation, the cross-sectional views illustrating the device structure may be partially enlarged, not according to the usual scale. Furthermore, the schematic diagrams are merely examples and should not limit the scope of protection of the present invention. In addition, actual fabrication should include three-dimensional spatial dimensions of length, width, and depth.

[0023] Please see Figures 1 to 14 As shown, the present invention provides an intelligent three-claw picking actuator with tactile perception, including a wrist module 1, a knuckle module 2 rotatably disposed on the upper end of the wrist module 1, three knuckle modules 2 disposed on the upper end of the wrist module 1 and arranged in a 120-degree distribution along the upper end of the wrist module 1, and a sensing module 3 fixedly connected to the clamping side of the knuckle module 2. The knuckle module 2 includes a first geared motor 201, a first knuckle 202, a second geared motor 203, a knuckle cover plate 204, a second knuckle 205, a third geared motor 206, a fixed cover plate 207, and a third knuckle 208. The output end of the first geared motor 201 is fixedly disposed on the outer edge of the wrist module 1. The interior of one end of the first knuckle 202 is fixedly connected to the first geared motor 201. The interior of the second geared motor 203 is fixedly connected to the interior of the other end of the first knuckle 202. The knuckle cover plate 204 is fixedly disposed on one side of the first knuckle 202 to confine the first geared motor 201 and the second geared motor 203 inside the first knuckle 202. One end of the second knuckle 205 is fixedly connected to the output end of the second geared motor 203. The third geared motor 206 is fixedly disposed inside the second knuckle 205. The fixed cover plate 207 is fixedly connected to the second knuckle 205. The third knuckle 208 is fixedly connected to the output end of the third geared motor 206.

[0024] Specifically, when the actuator starts the gripping operation, the control system sends a drive command to each finger module 2, the first reduction motor 201 starts, and its output drives the first finger 202 to rotate relative to the wrist module 1, so as to achieve the initial adjustment of the overall posture of the finger module 2. The second geared motor 203 starts, and its output drives the second finger joint 205 to bend relative to the first finger joint 202. The third geared motor 206 starts, and its output drives the third finger joint 208 to bend relative to the second finger joint 205. The modular packaging structure integrates each drive unit independently inside the knuckle, simplifying the assembly process and making it easy to disassemble and replace individually, which greatly reduces maintenance costs and difficulties. At the same time, the layout of the drive motor built-in makes the overall structure compact and lightweight, avoiding interference with the picking space and reducing the load on the robotic arm. Driven by a three-stage geared motor, the three finger modules 2 move synchronously, with their respective first finger 202, second finger 205 and third finger 208 unfolding or retracting in sequence to envelop and grasp the target fruit. During the grasping process, the sensing module 3, which is fixedly connected to the gripping sides of the first phalanx 202, the second phalanx 205, and the third phalanx 208, first comes into contact with the fruit surface, collects tactile signals, and transmits them to the control system. Through the independent drive and direct transmission design of the three-stage geared motor, the multi-joint coordinated control and rapid response of the phalanx are realized, enabling the actuator to adaptively adjust the grasping posture according to the shape of the fruit, thereby improving the adaptability to fruits of different shapes and sizes and the grasping success rate.

[0025] Please see Figures 1 to 4 As shown, the wrist module 1 includes a three-dimensional sensor 101, a mounting body 102, a sliding seat 103, a fixing plate 104, a connecting ring 105, and a compression spring 106. One end of the three-dimensional sensor 101 is connected to the corresponding end flange of the robotic arm. The mounting body 102 is fixedly installed at the other end of the three-dimensional sensor 101. One end of the sliding seat 103 is fixedly connected to the first reduction motor 201. Multiple sliding seats 103 are arranged in a ring at the other end of the mounting body 102. The sliding seats 103 are slidably installed inside the mounting body 102. The fixing plate 104 is fixedly installed at the other end of the mounting body 102 to limit the sliding seats 103 inside the mounting body 102. The connecting ring 105 is installed inside each sliding seat 103 to connect the sliding seats 103 into one unit. The compression spring 106 is installed between adjacent sliding seats 103 and is sleeved on the outer edge of the connecting ring 105. When the actuator performs the grasping operation, each finger module 2 applies a grasping force to the target fruit under the drive. The radial reaction force generated during the grasping process is transmitted to the sliding seat 103 fixedly connected to it through the first reduction motor 201. The sliding seat 103 slides in the annular guide groove opened inside the mounting body 102, causing the compression spring 106 between adjacent sliding seats 103 to undergo elastic deformation. The sliding of the sliding seat 103 causes each finger module 2 to automatically adjust the grasping position according to the actual shape and size of the fruit, realizing passive adaptive envelope for fruits of different sizes and shapes. The connecting ring 105 passes through the interior of each sliding seat 103, connecting multiple sliding seats 103 into one unit, so that the three finger modules 2 always maintain synchronous movement during radial sliding, ensuring that the gripping center always coincides with the geometric center of the actuator, avoiding gripping deviation or fruit slippage caused by asynchronous sliding of a single finger, improving the symmetry and stability of gripping, and ensuring the synchronicity and consistency of movement of each sliding seat 103 during the sliding process; Meanwhile, the compression spring 106 is positioned between adjacent sliding seats 103, which can effectively absorb and buffer energy when gripping impact or vibration occurs, and avoid rigid impact from damaging the fruit skin. When the gripping force is unloaded or the size of the fruit changes, the elastic restoring force of the compression spring 106 drives the sliding seat 103 to slide in the opposite direction, so that the knuckle module 2 automatically returns to the initial position. The fixing plate 104 is fixedly installed at the other end of the mounting body 102 to limit the sliding stroke of the sliding seat 103 and prevent it from coming out of the mounting body 102. Throughout the grasping process, the three-dimensional sensor 101 collects the grasping force signal transmitted through the mounting body 102 in real time and feeds it back to the control system to achieve closed-loop control of the grasping force.

[0026] Please see Figures 1 to 3 as well as Figure 5 , Figure 6 As shown, L-shaped mounting grooves are provided inside the mounting body 102, the first finger joint 202, the second finger joint 205 and the third finger joint 208. The interior of the mounting grooves cooperates with the output shafts of the first geared motor 201, the second geared motor 203 and the third geared motor 206. By creating L-shaped mounting slots inside the mounting body 102, the first finger joint 202, the second finger joint 205, and the third finger joint 208, and cooperating with the output shafts of the first geared motor 201, the second geared motor 203, and the third geared motor 206, dual limiting of the motor output shaft in the horizontal and vertical directions is achieved. This effectively prevents radial offset, axial movement, and circumferential rotation of the output shaft during operation, thereby improving the accuracy of power transmission and the reliability of the connection.

[0027] Please see Figures 1 to 3as well as Figure 5 , Figure 6 As shown, the output shafts of the first geared motor 201, the second geared motor 203, and the third geared motor 206 are provided with limiting surfaces, which cooperate with the fixing bolts that are provided through the mounting groove. By setting a limiting surface on the output shaft of the geared motor and cooperating with the fixing bolts that pass through the mounting groove, the axial and circumferential locking of the motor output shaft is achieved. The end of the fixing bolt abuts or is inserted into the limiting surface of the output shaft, which effectively prevents the motor from rotating circumferentially or moving axially due to vibration or load changes during operation, and significantly enhances the reliability and stability of the connection between the motor and the finger joint.

[0028] Please see Figures 7 to 9 As shown, the three-dimensional sensor 101 includes a base 1011, a sensitive beam 1012 and a guide column 1013. One end of the base 1011 is fixedly connected to the interior of the mounting body 102. Four sets of sensitive beams 1012 are fixedly connected to the outer edge of one end of the base 1011. The other end of the sensitive beam 1012 is fixedly connected to the guide column 1013. When the actuator performs a grasping operation, the grasping force generated by the contact between the target fruit and the knuckle module 2 is transmitted through the knuckle module 2 to the mounting body 102 of the wrist module 1. The mounting body 102 then transmits the load to the base 1011 of the three-dimensional sensor 101, which is fixedly connected to it. The load is then distributed through the base 1011 to the four sets of sensitive beams 1012, causing each sensitive beam 1012 to undergo elastic deformation corresponding to the magnitude and direction of the force. The deformation of the sensitive beam 1012 is further transmitted to the guide column 1013 fixedly connected to its other end. The guide column 1013 acts as a force convergence point, coordinating and unifying the deformation of the four sets of sensitive beams 1012. During the elastic deformation of the sensitive beam 1012, the strain gauges attached to its surface synchronously generate changes in resistance, converting the mechanical deformation into an electrical signal output, thus realizing real-time sensing of the magnitude and direction of the grasping force.

[0029] Please see Figures 7 to 9 as well as Figures 12 to 14 As shown, the sensitive beam 1012 is composed of a vertical floating beam 2121 and a horizontal floating beam 2122, and the angle between the vertical floating beam 2121 and the horizontal floating beam 2122 is 135 degrees. Strain gauges are attached to the surfaces of the vertical floating beam 2121 and the horizontal floating beam 2122, forming a Wheatstone full-bridge circuit for measuring the X, Y, and Z forces. The three sets of force measurement strain gauges 22 are X-direction force measurement strain gauge set 221, Y-direction force measurement strain gauge set 222, and Z-direction force measurement strain gauge set 223. X-direction force measurement strain gauge set 221 is attached to the outer side of the two vertical floating beams 2121 in the X direction near the base 1011; Y-direction force measurement strain gauge set 222 is attached to the outer side of the two vertical floating beams 2121 in the Y direction near the base 1011; Z-direction force measurement strain gauge set 223 is attached to the upper and lower sides of the two horizontal floating beams 2122 in the X direction away from the force guide column 1013.

[0030] X-direction force measurement strain gauge group 221 includes Rx1 strain gauge 2211, Rx2 strain gauge 2212, Rx3 strain gauge 2213 and Rx4 strain gauge 2214. Rx1 strain gauge 2211 and Rx2 strain gauge 2212 are attached to the outer side of the first vertical floating beam 2121 near the base 1011. Rx3 strain gauge 2213 and Rx4 strain gauge 2214 are attached to the outer side of the third vertical floating beam 2121 near the base 1011. Rx1 strain gauge 2211, Rx2 strain gauge 2212, Rx3 strain gauge 2213 and Rx4 strain gauge 2214 form a Wheatstone bridge for measuring X-direction force. The strain gauge group 222 for measuring force in the Y direction includes Rx5 strain gauge 2221, Rx6 strain gauge 2222, Rx7 strain gauge 2223 and Rx8 strain gauge 2224. Rx5 strain gauge 2221 and Rx6 strain gauge 2222 are attached to the outer side of the second vertical floating beam 2121 near the base 1011. Rx7 strain gauge 2223 and Rx8 strain gauge 2224 are attached to the outer side of the fourth vertical floating beam 2121 near the base 1011. Rx5 strain gauge 2221, Rx6 strain gauge 2222, Rx7 strain gauge 2223 and Rx8 strain gauge 2224 form a Wheatstone bridge for measuring force in the Y direction. Z-direction force measurement strain gauge group 223 includes Rx9 strain gauge 2231, Rx10 strain gauge 2232, Rx11 strain gauge 2233 and Rx12 strain gauge 2234. Rx9 strain gauge 2231 is attached to the outer side of the first horizontal floating beam 2122 away from the guide column 1013. Rx10 strain gauge 2232 is attached to the inner side of the first horizontal floating beam 2122 away from the guide column 1013. Rx11 strain gauge 2233 is attached to the inner side of the third horizontal floating beam 2122 away from the guide column 1013. Rx12 strain gauge 2234 is attached to the outer side of the third horizontal floating beam 2122 away from the guide column 1013. Rx9 strain gauge 2231, Rx10 strain gauge 2232, Rx11 strain gauge 2233 and Rx12 strain gauge 2234 form a Wheatstone bridge for measuring Z-direction force.

[0031] Please see Figures 1 to 3 as well as Figure 5 , Figure 6 , Figure 10 , Figure 11 As shown, the sensing module 3 includes a first mounting bracket 301, a second mounting bracket 302, a fingertip mounting bracket 303, and a contact pad 304. One end of the first mounting bracket 301 is fixedly connected to the first phalanx 202 by bolts. One end of the second mounting bracket 302 is fixedly connected to the second phalanx 205 by bolts. One end of the fingertip mounting bracket 303 is fixedly connected to the third phalanx 208 by bolts. The contact pad 304 is disposed at the other end of the fingertip mounting bracket 303 of the first mounting bracket 301 and the second mounting bracket 302. When the actuator performs a gripping operation, the control system drives each finger module 2 to move. The first finger 202, the second finger 205 and the third finger 208 respectively drive the first mounting frame 301, the second mounting frame 302 and the fingertip mounting frame 303 fixedly connected to them to move synchronously. As the knuckles gradually close, the contact pads 304 fixed to the other end of each mounting bracket gradually approach and contact the surface of the target fruit. Since the first mounting bracket 301, the second mounting bracket 302 and the fingertip mounting bracket 303 are independently fixed to different knuckles, the three can independently adjust their positions according to the movement posture of the corresponding knuckles, so that the contact pads 304 form multi-point envelope contact with the fruit under the action of different knuckles. When the fruit is irregular in shape, each mounting bracket can independently adapt to the undulations of the fruit surface, ensuring that the contact pad 304 maintains a good fit with the fruit surface. During the grasping process, the pressure of the fruit acting on the contact pad 304 is transmitted to each mounting bracket, and then to the strain gauge inside the corresponding finger joint, realizing the real-time acquisition and feedback of tactile signals.

[0032] Please see Figure 10 As shown, the first mounting bracket 301, the second mounting bracket 302, the fingertip mounting bracket 303 and the contact pad 304 are provided with a parallel beam flexible structure, and strain gauges are attached to the surface of the parallel beam structure. The parallel beam flexible structure set between the first mounting bracket 301, the second mounting bracket 302, the fingertip mounting bracket 303 and the contact pad 304 constitutes a micro elastic deformation unit. When the contact pad 304 is in contact with the fruit surface and subjected to force, the parallel beam structure generates a small elastic deformation proportional to the magnitude of the contact force. The strain gauge attached to its surface senses the amount of deformation in real time and converts it into a resistance change signal, thereby realizing accurate detection of the grasping contact force.

[0033] Please see Figure 11 As shown, the contact surface of the contact pad 304 is provided with honeycomb-shaped slots; The honeycomb-shaped slots on the contact surface of the contact pad 304 form an array of microporous structures, which significantly reduces the rigidity of the contact area while maintaining the overall structural strength of the pad. This allows the pad to undergo local micro-deformation according to the undulations of the fruit surface during the gripping process, increasing the friction coefficient of the contact pad 304 surface and creating a micro-interlocking effect between the pad and the smooth fruit surface to achieve adaptive adhesion to irregular surfaces. The hexagonal lattice structure of the honeycomb-like slots makes the stress distribution on the contact surface more uniform when under pressure, avoiding local stress concentration, effectively reducing point pressure on the fruit skin, and lowering the risk of damage.

[0034] Please see Figure 4 As shown, the mounting body 102 has an annular guide groove inside, and the annular guide groove is divided into three sections. Each section of the guide groove has a corresponding sliding seat 103 slidably disposed inside. The annular guide groove inside the mounting body 102 adopts a three-segment structure, with a corresponding sliding seat 103 independently sliding in each segment of the guide groove, forming a precise radial sliding guide. At the same time, the movement space of the three sliding seats 103 is independent of each other, so that each sliding seat 103 can slide independently according to the difference in the load on the corresponding finger module 2 without interfering with each other. This realizes the separate adjustment of the radial position of each finger and better adapts to the changing needs of gripping force in different directions.

[0035] The working principle of this invention is as follows: when the actuator starts the gripping operation, the control system sends a drive command to each finger module 2, the first reduction motor 201 starts, and its output end drives the first finger 202 to rotate relative to the wrist module 1, thereby realizing the initial adjustment of the overall posture of the finger module 2. The second geared motor 203 starts, and its output drives the second finger joint 205 to bend relative to the first finger joint 202. The third geared motor 206 starts, and its output drives the third finger joint 208 to bend relative to the second finger joint 205. The modular packaging structure integrates each drive unit independently inside the knuckle, simplifying the assembly process and making it easy to disassemble and replace individually, which greatly reduces maintenance costs and difficulties. At the same time, the layout of the drive motor built-in makes the overall structure compact and lightweight, avoiding interference with the picking space and reducing the load on the robotic arm. Driven by a three-stage geared motor, the three finger modules 2 move synchronously, with their respective first finger 202, second finger 205 and third finger 208 unfolding or retracting in sequence to envelop and grasp the target fruit. During the grasping process, the sensing module 3, which is fixedly connected to the gripping sides of the first phalanx 202, the second phalanx 205, and the third phalanx 208, first comes into contact with the fruit surface, collects tactile signals, and transmits them to the control system. Through the independent drive and direct transmission design of the three-stage geared motor, the multi-joint coordinated control and rapid response of the phalanx are realized, enabling the actuator to adaptively adjust the grasping posture according to the shape of the fruit, thereby improving the adaptability to fruits of different shapes and sizes and the grasping success rate.

[0036] The above description is merely a preferred embodiment of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention. Structures, devices, and operating methods not specifically described or explained in this invention are implemented according to conventional methods in the art unless otherwise specified or limited.

Claims

1. An intelligent three-claw harvesting actuator with tactile sensing, characterized in that: Includes a wrist module (1), and a knuckle module (2) is rotatably provided on the upper end of the wrist module (1). Three knuckle modules (2) are provided on the upper end of the wrist module (1) and are arranged in a 120-degree distribution along the upper end of the wrist module (1). A sensing module (3) is fixedly connected to the clamping side of the knuckle module (2). The knuckle module (2) includes a first geared motor (201), a first knuckle (202), a second geared motor (203), a knuckle cover plate (204), a second knuckle (205), a third geared motor (206), a fixed cover plate (207), and a third knuckle (208). The output end of the first geared motor (201) is fixedly disposed on the outer edge of the wrist module (1). The interior of one end of the first knuckle (202) is fixedly connected to the first geared motor (201), and the interior of the second geared motor (203) is fixedly connected to the interior of the other end of the first knuckle (202). Next, the knuckle cover plate (204) is fixedly disposed on one side of the first knuckle (202) to restrict the first geared motor (201) and the second geared motor (203) inside the first knuckle (202). One end of the second knuckle (205) is fixedly connected to the output end of the second geared motor (203). The third geared motor (206) is fixedly disposed inside the second knuckle (205). The fixed cover plate (207) is fixedly connected to the second knuckle (205). The third knuckle (208) is fixedly connected to the output end of the third geared motor (206).

2. The intelligent three-claw picking actuator with tactile perception according to claim 1, characterized in that: The wrist module (1) includes a three-dimensional sensor (101), a mounting body (102), a sliding seat (103), a fixing plate (104), a connecting ring (105), and a compression spring (106). One end of the three-dimensional sensor (101) is connected to the corresponding end flange of the robotic arm. The mounting body (102) is fixedly mounted on the other end of the three-dimensional sensor (101). One end of the sliding seat (103) is fixedly connected to the first reduction motor (201). The sliding seat (103) forms a ring at the other end of the mounting body (102). The mounting body has multiple sliding seats (103) that are slidably disposed inside the mounting body (102). The fixing plate (104) is fixedly disposed at the other end of the mounting body (102) to limit the sliding seats (103) inside the mounting body (102). The connecting ring (105) is disposed inside each sliding seat (103) to connect each sliding seat (103) into a whole. The compression spring (106) is disposed between adjacent sliding seats (103) and is sleeved on the outer edge of the connecting ring (105).

3. The intelligent three-claw picking actuator with tactile perception according to claim 2, characterized in that: The mounting body (102), the first phalanx (202), the second phalanx (205) and the third phalanx (208) are provided with L-shaped mounting grooves, and the interior of the mounting grooves cooperates with the output shafts of the first geared motor (201), the second geared motor (203) and the third geared motor (206).

4. The intelligent three-claw picking actuator with tactile perception according to claim 3, characterized in that: The output shafts of the first geared motor (201), the second geared motor (203), and the third geared motor (206) are provided with limiting surfaces, which are engaged with fixing bolts that pass through the mounting groove.

5. The intelligent three-claw picking actuator with tactile perception according to claim 2, characterized in that: The three-dimensional sensor (101) includes a base (1011), a sensitive beam (1012), and a guide column (1013). One end of the base (1011) is fixedly connected to the interior of the mounting body (102). Four sets of sensitive beams (1012) are fixedly connected to the outer edge of one end of the base (1011), and the other end of the sensitive beam (1012) is fixedly connected to the guide column (1013).

6. The intelligent three-claw picking actuator with tactile perception according to claim 5, characterized in that: The sensitive beam (1012) is composed of a vertical floating beam (2121) and a horizontal floating beam (2122), and the angle between the vertical floating beam (2121) and the horizontal floating beam (2122) is 135 degrees. Strain gauges are attached to the surfaces of the vertical floating beam (2121) and the horizontal floating beam (2122), forming a Wheatstone full-bridge circuit for measuring X, Y, and Z forces.

7. The intelligent three-claw picking actuator with tactile perception according to claim 1, characterized in that: The sensing module (3) includes a first mounting bracket (301), a second mounting bracket (302), a fingertip mounting bracket (303), and a contact pad (304). One end of the first mounting bracket (301) is fixedly connected to the first knuckle (202) by bolts. One end of the second mounting bracket (302) is fixedly connected to the second knuckle (205) by bolts. One end of the fingertip mounting bracket (303) is fixedly connected to the third knuckle (208) by bolts. The contact pad (304) is disposed at the other end of the first mounting bracket (301), the second mounting bracket (302), and the fingertip mounting bracket (303).

8. The intelligent three-claw picking actuator with tactile perception according to claim 7, characterized in that: The first mounting bracket (301), the second mounting bracket (302), the fingertip mounting bracket (303) and the contact pad (304) are provided with a parallel beam flexible structure, and strain gauges are attached to the surface of the parallel beam structure.

9. The intelligent three-claw picking actuator with tactile perception according to claim 7, characterized in that: The contact surface of the contact pad (304) is provided with honeycomb-shaped slots.

10. The intelligent three-claw picking actuator with tactile perception according to claim 2, characterized in that: The mounting body (102) has an annular guide groove inside, and the annular guide groove is divided into three sections. Each section of the guide groove has a corresponding sliding seat (103) slidably disposed inside.

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