Multi-degree of freedom functional gripper

Abstract

The application discloses a multi-degree-of-freedom functional clamping jaw and belongs to the clamping jaw field. The multi-degree-of-freedom functional clamping jaw comprises a clamping jaw assembly, a parallel spherical motion mechanism arranged at the tail end of the clamping jaw assembly and used for driving the multi-degree-of-freedom rotation of the clamping jaw assembly, a moving surface connecting seat fixedly installed at the tail end of the clamping jaw assembly, a first motor, a second motor and a third motor coaxially arranged at the tail end of the moving surface connecting seat and connected in series through a connecting assembly and used for driving the multi-degree-of-freedom rotation of the moving surface connecting seat, and three motor positioning barrels fixedly installed outside the three groups of motors. The multi-degree-of-freedom functional clamping jaw adopts the parallel spherical motion mechanism, forms a closed chain constraint, effectively reduces the accumulation of joint errors, improves the end stiffness and positioning accuracy, and is particularly suitable for high-precision scenes such as C electronic assembly and medical cavity operation.

Description

Technical Field

[0001] This invention belongs to the field of gripper technology, specifically relating to a multi-degree-of-freedom functional gripper. Background Technology

[0002] A gripper is an actuator installed at the end of a robot, robotic arm, or automated equipment. Its core function is to grasp, hold, move, or place objects, much like human fingers. It typically consists of a drive source (such as a motor or cylinder), a transmission mechanism (such as a linkage or gear), and gripping components (finger-like or plate-like). Based on the driving method, they are mainly divided into pneumatic grippers, electric grippers, and hydraulic grippers. They are widely used in automated production lines for industrial assembly, packaging, and handling, and are key components for achieving precise gripping and automated operation.

[0003] Traditional robot end effector grippers mostly rely on the coordinated movement of the body joints and the cascaded wrists for posture control. This has three significant drawbacks in practical applications, limiting the robot's ability to operate in precise and confined spaces:

[0004] First, serial wrists suffer from inherent precision and rigidity deficiencies. Most mainstream 6-axis robot end effectors employ an open-chain structure with 2-3 rotary joints connected in series. The cumulative joint errors lead to a decrease in end-effector positioning accuracy, and the cantilever structure lacks sufficient rigidity. Solutions that increase size often impact the workspace. In scenarios such as precision assembly in 3C electronics, welding in confined automotive spaces, and intracavitary medical procedures, traditional serial wrists, due to their large size and significant errors, are insufficient for performing high-precision, delicate operations in specific environments, becoming a technological bottleneck.

[0005] Second, structural coupling leads to parasitic motion, resulting in poor adaptability to high-precision scenarios. Traditional commercial spherical wrists have extremely high degrees of freedom coupling, which can cause unexpected translational displacements, or parasitic motions, during attitude adjustments, directly leading to gripper positioning deviations. These problems require complex algorithm compensation, which has a high technical threshold and cannot completely eliminate fundamental structural errors.

[0006] Third, the drive layout is unreasonable, resulting in high engineering implementation costs. Existing spherical parallel wrists mostly use motors arranged in a circular pattern, with excessively large radial dimensions, making them unsuitable for small robot end effectors. A few compact designs sacrifice load-bearing capacity and range of motion, and require high precision in processing and assembly, resulting in a high cost per prototype. They are mostly used in laboratory research and are not suitable for large-scale promotion in small and medium-sized industrial scenarios and university scientific and technological innovation fields.

[0007] Therefore, developing a multi-degree-of-freedom functional gripper to address the above problems is a pressing issue that needs to be resolved by those skilled in the art. Summary of the Invention

[0008] This application provides a multi-degree-of-freedom functional gripper, which aims to solve the existing problems mentioned in the background art.

[0009] To achieve the above objectives, this application provides the following technical solution:

[0010] A multi-degree-of-freedom functional gripper includes a gripper assembly and a parallel spherical motion mechanism disposed at the tail end of the gripper assembly for driving the gripper assembly to rotate in multiple degrees of freedom. The parallel spherical motion mechanism includes a moving surface connecting seat fixedly installed at the tail end of the gripper assembly and a first motor, a second motor, and a third motor coaxially disposed at the tail end of the moving surface connecting seat and connected in series by a connecting assembly for driving the moving surface connecting seat to rotate in multiple degrees of freedom. The connecting assembly includes three sets of motor positioning cylinders fixedly installed outside the three sets of motors, an external frame fixedly installed outside the tail end of the motor positioning cylinders, and an output flange fixedly installed inside the tail end of the motor positioning cylinders for connecting the output shafts of adjacent motors. The tail end of the first motor is fixedly installed on the output shaft of the second motor through the output flange, and the tail end of the second motor is fixedly installed on the output shaft of the third motor through another set of the output flanges.

[0011] Preferably, a washer with a shim support is fixedly mounted on the output shaft of the first motor. A ball joint connected to the moving surface connecting seat is screwed onto the washer support. A first drive chain is fixedly mounted on the washer. The head of the first drive chain is hinged to a first driven chain hinged to the side of the moving surface connecting seat. A second drive chain is fixedly mounted on the external frame corresponding to the first motor. The head of the second drive chain is hinged to a second driven chain hinged to the side of the moving surface connecting seat. A third drive chain is fixedly mounted on the external frame corresponding to the second motor. The head of the third drive chain is hinged to a third driven chain hinged to the side of the moving surface connecting seat. The third driven chain, the second driven chain, and the first driven chain are arranged in a circular array on the side of the moving surface connecting seat. In this way, the tail of the gripper assembly is fixedly connected to the moving surface connecting seat and connected to the drive chain driven by the three motors through a branch chain composed of three circularly arranged driven chains and drive chains. The ends of the three branches jointly constrain the movement of the moving surface connector, causing it to rotate spherically around a fixed point, thereby achieving multi-degree-of-freedom attitude adjustment. Since the three driven chains are distributed in a ring array, the rotation of any motor will cause a change in the attitude of the moving surface connector. By coordinating and controlling the speed and direction of the three motors, the gripper assembly can achieve any attitude in space.

[0012] Preferably, the first drive chain, the second drive chain, and the third drive chain are all installed vertically around the axis. The three sets of drive chains maintain a 45-degree angle with the axis and the motor mounting plane, and are on the same plane. The axes of the first driven chain, the second driven chain, and the third driven chain all intersect with the center of the ball joint.

[0013] Preferably, the gripper assembly includes a gripper housing fixedly mounted to the moving surface connecting seat, a pair of support plates symmetrically fixedly mounted on the gripper housing, a pair of rhomboid clamping rods symmetrically hinged between the two support plates with their movable ends close to or far from each other, a pair of drive connecting rods respectively hinged to the side of the two rhomboid clamping rods close to each other, a gripper motor fixedly mounted in the gripper housing, a screw rotatably mounted on the gripper housing and connected to the output shaft of the gripper motor, and a drive slider screwed to the screw and moving close to or far from the gripper housing and hinged to the two drive connecting rods, wherein each movable end of the rhomboid clamping rods is fixedly mounted with a chuck.

[0014] Preferably, the motor positioning cylinder has an electrical connection port on its side, and the outer frame has at least two sets of wire-passing ports arranged in a ring array on its flange.

[0015] Preferably, the tail end of the third motor is fixedly mounted with a robot mounting connector via a connector and bolts.

[0016] Preferably, the tail end of the first drive chain has a flange structure and is fixedly mounted on the gasket with bolts. The tail ends of the second drive chain and the third drive chain are both fixedly mounted on the corresponding external frame with two sets of bolts. The motor positioning cylinder, the external frame and the output flange are all provided with at least three sets of through holes arranged in a ring array on their sides for passing through and screwing three bolts onto the motor housing.

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] 1. It adopts a parallel spherical motion mechanism to form a closed chain constraint, which effectively reduces the accumulation of joint errors, improves end-effector stiffness and positioning accuracy, and is particularly suitable for high-precision scenarios such as C-electronic assembly and medical cavity operation;

[0019] 2. By using the geometric constraints of the three driven chains and the moving surface connection seat, the attitude adjustment is mainly performed around a fixed center, which significantly reduces the parasitic translational motion common in traditional spherical wrists and avoids the complexity of additional compensation algorithms.

[0020] 3. The three motors adopt a coaxial series layout and are centrally arranged using motor positioning cylinders and external frames, which avoids the large radial size caused by the dispersed arrangement of motors around the circumference, making it easier to install and use in the end effector of small robots or in confined spaces.

[0021] 4. By replacing some high-precision and complex joints with chain drive, the reliance on ultra-high precision machining and assembly of individual parts is reduced. At the same time, the high degree of modularity facilitates mass production and later maintenance, making it more suitable for promotion and application in small and medium-sized industrial scenarios and scientific and technological innovation fields in universities.

[0022] 5. The multi-degree-of-freedom attitude adjustment function is directly integrated into the tail of the gripper assembly, which can complete fine attitude adjustment without relying on too many joint movements of the robot body, thus improving the robot's working ability and flexibility in narrow spaces. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of a multi-degree-of-freedom functional gripper.

[0024] Figure 2 This is a schematic diagram of the structure of a gripper assembly for a multi-degree-of-freedom functional gripper;

[0025] Figure 3 This is a schematic diagram of the internal structure of a multi-degree-of-freedom functional gripper;

[0026] Figure 4 A schematic diagram of the split structure of a connecting component for a multi-degree-of-freedom functional gripper;

[0027] Figure 5 for Figure 3 Enlarged structural diagram at point A;

[0028] Figure 6 This is a schematic diagram of the structure of a connector for a multi-degree-of-freedom functional gripper.

[0029] Explanation of markings in the diagram:

[0030] 1. Gripper assembly; 11. Gripper housing; 12. Support plate; 13. Diamond-shaped clamping rod assembly; 131. Chuck; 14. Drive linkage; 15. Drive slider; 16. Screw; 17. Gripper motor;

[0031] 2. Parallel spherical motion mechanism; 21. First motor; 211. First driving chain; 212. First driven chain; 22. Second motor; 221. Second driving chain; 222. Second driven chain; 23. Third motor; 231. Third driving chain; 232. Third driven chain; 24. Moving surface connecting seat; 25. Ball joint; 26. Washer support; 261. Washer;

[0032] 3. Connecting components; 31. Motor positioning cylinder; 311. Power connection port; 32. External frame; 321. Cable entry port; 33. Output flange;

[0033] 4. Robot mounting connector; 41. Connector. Detailed Implementation

[0034] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0035] This embodiment provides a multi-degree-of-freedom functional gripper, such as... Figures 1-6 As shown, the multi-degree-of-freedom functional gripper includes a gripper assembly 1 and a parallel spherical motion mechanism 2 disposed at the tail end of the gripper assembly 1 for driving the multi-degree-of-freedom rotation of the gripper assembly 1. The parallel spherical motion mechanism 2 includes a moving surface connecting seat 24 fixedly installed at the tail end of the gripper assembly 1 and a first motor 21, a second motor 22, and a third motor 23 coaxially disposed at the tail end of the moving surface connecting seat 24 and connected in series by a connecting component 3 for driving the multi-degree-of-freedom rotation of the moving surface connecting seat 24. The connecting component 3 includes three sets of motor positioning cylinders 31 fixedly installed outside the three sets of motors, an external frame 32 fixedly installed outside the tail end of the motor positioning cylinders 31, and an output flange 33 fixedly installed inside the tail end of the motor positioning cylinders 31 for connecting the output shafts of adjacent motors. The tail end of the first motor 21 is fixedly installed on the output shaft of the second motor 22 through the output flange 33, and the tail end of the second motor 22 is fixedly installed on the output shaft of the third motor 23 through another set of output flanges 33.

[0036] A washer 261 with a washer support 26 is fixedly installed on the output shaft of the first motor 21. A ball joint 25 connected to the moving surface connecting seat 24 is screwed onto the washer support 26. A first driving chain 211 is fixedly installed on the washer 261. A first driven chain 212 hinged to the head of the first driving chain 211 is hinged to the side of the moving surface connecting seat 24. A second driving chain 221 is fixedly installed on the external frame 32 corresponding to the first motor 21. A second driven chain 222 hinged to the head of the second driving chain 221 is hinged to the side of the moving surface connecting seat 24. A third driving chain 231 is fixedly installed on the external frame 32 corresponding to the second motor 22. A third driven chain 232 hinged to the head of the third driving chain 231 is hinged to the side of the moving surface connecting seat 24. The third driven chain 232, the second driven chain 222 and the first driven chain 212 are arranged in a ring array on the side of the moving surface connecting seat 24.

[0037] In operation, the control system sends attitude adjustment commands to the first motor 21, the second motor 22, and the third motor 23. Each motor calculates the required output angle based on the target attitude. The third motor 23 starts, driving the second motor 22 to rotate around its own axis via the output flange 33. The second motor 22 starts, driving the first motor 21 to rotate around its own axis via the output flange 33. The first motor 21 starts, driving its own output shaft to rotate. When the output shaft of the first motor 21 rotates, it directly pushes the moving surface connecting seat 24 to generate initial oscillation through the shim support 26 and the ball joint 25. On the other hand, the first motor 21 drives... The first active chain 211 pulls the side of the moving surface connecting seat 24 through the first driven chain 212 to assist in adjusting the posture. When the second motor 22 starts, it drives the second active chain 221, which pulls the side of the moving surface connecting seat 24 through the second driven chain 222, superimposing the second degree of freedom rotation. When the third motor 23 starts, it drives the third active chain 231, which pulls the side of the moving surface connecting seat 24 through the third driven chain 232, superimposing the third degree of freedom rotation. The three driven chains work together with the ball joint 25 to limit the unintended translation of the moving surface connecting seat 24, so that the gripper assembly 1 can accurately reach the target posture and complete operations such as gripping and assembly.

[0038] Specifically, the first drive chain 211, the second drive chain 221, and the third drive chain 231 are all vertically installed around the axis. The three sets of drive chains maintain a 45-degree angle with the axis and the motor mounting plane, and are in the same plane. The axes of the first driven chain 212, the second driven chain 222, and the third driven chain 232 all intersect the center of the ball joint 25. The first drive chain 211, the second drive chain 221, and the third drive chain 231 are arranged coplanarly with the vertical axis as the reference, maintaining a 45-degree angle with the motor mounting plane. This ensures that the tension direction of the chain drive is accurately projected onto the plane where the center of the ball joint 25 is located, ensuring that the three sets of chains can provide pure torque output without introducing lateral force in any posture. This geometric configuration significantly improves the linearity and decoupling of posture control, avoids the unexpected displacement caused by lever arm offset in traditional spherical mechanisms, and achieves sub-millimeter-level posture stability.

[0039] Specifically, the gripper assembly 1 includes a gripper housing 11 fixedly mounted to the moving surface connecting seat 24, a pair of support plates 12 symmetrically fixedly mounted on the gripper housing 11, a pair of rhomboid clamping rod groups 13 symmetrically hinged between the two support plates 12 with their movable ends approaching or moving away from each other, a pair of drive connecting rods 14 respectively hinged to the two rhomboid clamping rod groups 13 on their respective sides approaching each other, a gripper motor 17 fixedly mounted inside the gripper housing 11, a screw 16 rotatably mounted on the gripper housing 11 and connected to the output shaft of the gripper motor 17, and a drive rod 16 screwed to the screw 16, moving towards or away from the gripper housing 11 and hinged to the two drive connecting rods 14. The slider 15 has a chuck 131 fixedly installed on the movable end of the rhomboid clamping rod group 13. The gripper assembly 1 is rigidly connected to the moving surface connecting seat 24 through the gripper housing 11. The rhomboid clamping rod group 13 is supported by a pair of support plates 12 to form a self-centering clamping structure. The gripper motor 17 drives the screw 16 to rotate, which drives the slider 15 to move linearly along the axial direction. The two rhomboid clamping rod groups 13 are pushed symmetrically to open and close through the drive connecting rod 14. This mechanism efficiently converts the rotational motion into parallel clamping force. The chuck 131 always maintains center alignment during the movement, effectively avoiding off-center loading and jamming. It is suitable for non-destructive gripping of small and fragile objects.

[0040] Furthermore, the motor positioning cylinder 31 has a power inlet 311 on its side, and the flange of the external frame 32 has at least two sets of cable trays 321 arranged in a ring array; providing independent and tangle-free cable routing channels for the power lines of the three motors and the encoder signal lines, ensuring that the cables are not affected by torsional fatigue during continuous multi-degree-of-freedom rotation, improving the long-term reliability of the system, simplifying the maintenance process, reducing the failure rate caused by cable wear, and making it suitable for continuous operation requirements in high-cycle industrial scenarios.

[0041] Furthermore, the tail end of the third motor 23 is fixedly mounted with a robot mounting connector 4 via a connector 41 and bolts; this enables rapid and standardized docking between the gripper module and the end effector of the robotic arm, reducing assembly levels and weight redundancy, improving overall rigidity and shortening installation time.

[0042] More specifically, the tail end of the first drive chain 211 has a flange structure and is fixedly mounted on the gasket 261 with bolts. The tail ends of the second drive chain 221 and the third drive chain 231 are both fixedly mounted on the corresponding external frame 32 with two sets of bolts. The motor positioning cylinder 31, the external frame 32 and the output flange 33 are all provided with at least three sets of through holes arranged in a ring array on their sides for passing through and screwing into the motor housing with three bolts. This differentiated connection method takes into account both the rigidity of power transmission and the adjustability of installation. The gasket 261 serves as the reference surface for torque transmission, ensuring that the output shaft of the first motor 21 is strictly coaxial with the center of the ball joint 25. The double bolt fixing of the external frame 32 enhances the vibration resistance of the chain system. The overall structure maintains zero-backlash transmission under high-frequency start-stop conditions. By passing through and screwing into the motor housing with three bolts, a rigid locking structure with three evenly distributed points is formed, which effectively disperses the installation stress and simplifies the installation process.

[0043] The above description is merely a preferred embodiment of this application, but the scope of protection of this application is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in this application, based on the technical solution and concept of this application, should be included within the scope of protection of this application.

Claims

1. A multi-degree-of-freedom functional gripper, characterized in that: It includes a gripper assembly (1) and a parallel spherical motion mechanism (2) disposed at its tail end for driving the gripper assembly (1) to rotate in multiple degrees of freedom. The parallel spherical motion mechanism (2) includes a moving surface connecting seat (24) fixedly installed at the tail end of the gripper assembly (1) and a first motor (21), a second motor (22) and a third motor (23) coaxially arranged at the tail end of the moving surface connecting seat (24) and connected in series by a connecting assembly (3) for driving the moving surface connecting seat (24) to rotate in multiple degrees of freedom. The connecting assembly (3) includes a motor positioning cylinder (31), an external frame (32), and an output flange (33). The motor positioning cylinder (31) is provided in three sets, which are respectively fixedly installed outside the first motor (21), the second motor (22), and the third motor (23). The external frame (32) is fixedly installed outside the tail end of each set of motor positioning cylinders (31). The output flange (33) is fixedly installed inside the tail end of the motor positioning cylinder (31) for connecting the output shafts of adjacent motors. The tail end of the first motor (21) is fixedly installed on the output shaft of the second motor (22) through the output flange (33). The tail end of the second motor (22) is fixedly installed on the output shaft of the third motor (23) through another set of output flanges (33).

2. The multi-degree-of-freedom functional gripper according to claim 1, characterized in that: A washer (261) with a washer support (26) is fixedly installed on the output shaft of the first motor (21); a ball joint (25) connected to the moving surface connecting seat (24) is screwed onto the washer support (26); a first drive chain (211) is fixedly installed on the washer (261); a first driven chain (212) is hinged to the head of the first drive chain (211); a second drive chain (221) is fixedly installed on the external frame (32) of the first motor (21); a second driven chain (222) is hinged to the head of the second drive chain (221); a third drive chain (231) is fixedly installed on the external frame (32) of the second motor (22); a third driven chain (232) is hinged to the head of the third drive chain (231); the third driven chain (232), the second driven chain (222) and the first driven chain (212) are arranged in a ring array and are hinged to the side of the moving surface connecting seat (24).

3. The multi-degree-of-freedom functional gripper according to claim 2, characterized in that: The first driving chain (211), the second driving chain (221) and the third driving chain (231) are all vertically installed around the same axis and maintain a 45-degree angle with the axis and the motor mounting plane, and are in the same plane; the axes of the first driven chain (212), the second driven chain (222) and the third driven chain (232) all intersect with the center of the ball joint (25).

4. The multi-degree-of-freedom functional gripper according to claim 1, characterized in that: The gripper assembly (1) includes a gripper housing (11), a support plate (12), a diamond-shaped gripper rod assembly (13), a drive link (14), a gripper motor (17), a screw (16), and a drive slider (15). The gripper housing (11) is fixedly installed with the moving surface connecting seat (24); the support plate (12) is symmetrically fixedly installed on the gripper housing (11); the rhomboid clamping rod group (13) is symmetrically hinged between the two support plates (12) with its movable ends close to or far from each other, and the movable end of the clamping rod group (13) is fixedly installed with a chuck (131); the drive connecting rod (14) is respectively hinged to the two rhomboid clamping rod groups (13) on the side close to each other; the gripper motor (17) is fixedly installed inside the gripper housing (11); the screw (16) is rotatably installed on the gripper housing (11) and connected to the output shaft of the gripper motor (17); the drive slider (15) is screwed to the screw (16) and moves close to or away from the gripper housing (11), and is hinged to the two drive connecting rods (14).

5. A multi-degree-of-freedom functional gripper according to claim 1, characterized in that: The motor positioning cylinder (31) has an electrical connection port (311) on its side; the outer frame (32) has at least two sets of wire insertion ports (321) arranged in a ring array on its flange.

6. A multi-degree-of-freedom functional gripper according to claim 1, characterized in that: The tail end of the third motor (23) is fixedly mounted with a robot mounting connector (4) via a connector (41) and bolts.

7. A multi-degree-of-freedom functional gripper according to claim 3, characterized in that: The tail end of the first drive chain (211) has a flange structure and is fixedly mounted on the gasket (261) by bolts; the tail ends of the second drive chain (221) and the third drive chain (231) are both fixedly mounted on the corresponding external frame (32) by two sets of bolts; the motor positioning cylinder (31), the external frame (32) and the output flange (33) are all provided with at least three sets of through holes arranged in a ring array on their sides, which are used to pass through and screw onto the motor housing by three bolts.

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