A three-degree-of-freedom robot wrist with bidirectional active clutch and braking functions

Abstract

A three-degree-of-freedom robot wrist with bidirectional active clutch and braking functions, which relates to the field of mechatronics technology. The end parallel joints are installed on the top of the frame through universal joints, and two linear motors are installed on both sides. The bottom shell and the top shell are rotatably connected. The bottom rotating seat is fixed inside the bottom shell, and the top rotating seat is rotatably connected to the bottom rotating seat. The bottom of the frame is fixed on the top rotating seat, and the upper end of the frame is fixedly connected to the top shell. The rotating motor is fixed at the inner bottom of the frame and is connected to the bidirectional clutch through a planetary gear reducer. The rotating shaft of the bidirectional clutch is fixedly connected to the bottom rotating seat. A torsional motion is added on the basis of pitching and yaw to achieve three-degree-of-freedom motion output. It is centrally designed in the housing mechanism in a series-parallel hybrid manner, reasonably controlling the axial dimension, and realizing bidirectional unlocking and locking of torsion through the bidirectional clutch, effectively improving the flexibility of the robot wrist.

Description

Technical Field

[0001] The present invention relates to the technical field of mechatronics, and specifically to a three-degree-of-freedom robot wrist with bidirectional active clutch and braking functions. Background Art

[0002] In a conventional humanoid electromechanical robotic arm, the robot wrist used to connect the hand and the arm generally has two degrees of freedom, pitch and yaw, through the forward and reverse telescoping of a parallel mechanism. In the situation where the requirements for the operating flexibility of the robot are becoming increasingly stringent, it has gradually become difficult to meet the hand movement requirements of the robot.

[0003] In addition, scholars in the current field have also conducted some research and designs on such problems. Generally, a rotary motor is added at the end of the wrist joint to achieve the motion output of three degrees of freedom. However, this will greatly increase the axial dimension of the wrist joint and cannot be applied when the dimension of the wrist joint, especially the axial dimension, has relatively strict requirements. In addition, the torsional movement of the wrist joint needs to be quickly locked after reaching the specified angle. Only controlling the rotation angle of the rotary motor is prone to the drawback of excessive torsion and it is difficult to achieve accurate braking of the torsion angle. Summary of the Invention

[0004] To solve the deficiencies in the background art, the present invention provides a three-degree-of-freedom robot wrist with bidirectional active clutch and braking functions. It adds a torsional movement on the basis of pitch and yaw to achieve three-degree-of-freedom motion output. It is centrally designed in the housing mechanism in a series-parallel hybrid manner, reasonably controls the axial dimension, and realizes two-way unlocking and locking of torsion through a bidirectional clutch, effectively improving the flexibility of the robot wrist.

[0005] To achieve the above object, the present invention adopts the following technical solutions: A three-degree-of-freedom robot wrist with bidirectional active clutch and braking functions, including a frame, a terminal parallel joint, and two linear motors. The main body of the terminal parallel joint is disc-shaped, and its bottom center is installed on the top of the frame through a universal joint. The two linear motors are arranged in parallel and eccentrically arranged with the terminal parallel joint. The bottom ends of the two linear motors are respectively connected to the bottom of the frame through spherical hinges. An N-shaped connecting beam is arranged at the eccentric position of the bottom of the terminal parallel joint. The telescopic ends of the two linear motors are respectively hinged to the two ends of the N-shaped connecting beam through connecting pieces. The robot wrist further includes a bottom shell, a top shell, a top rotating seat, a rotating motor, a planetary gear reducer, a bidirectional clutch, and a bottom rotating seat. The bottom shell and the top shell are two coaxial cylindrical shells and are rotatably connected. The bottom rotating seat is fixed inside the bottom shell. The top rotating seat is arranged at the lower end inside the top shell and is rotatably connected to the bottom rotating seat. Both the top rotating seat and the bottom rotating seat adopt an annular structure. The bottom of the frame is fixed at the center position of the upper surface of the top rotating seat. The upper end of the frame is fixedly connected to the top shell. The terminal parallel joint extends out of the top shell. The rotating motor is longitudinally fixed at the bottom inside the frame. The planetary gear reducer is longitudinally fixed below the frame. The output shaft of the rotating motor passes through the frame and is connected to the input end of the planetary gear reducer. The bidirectional clutch is longitudinally fixed below the planetary gear reducer. The bidirectional clutch is coaxially provided with a rotating shaft, which allows and restricts the forward and reverse rotation of the rotating shaft in the unlocked and locked states respectively. The upper end of the rotating shaft is connected to the output end of the planetary gear reducer, and the lower end of the rotating shaft is fixedly connected to the bottom rotating seat.

[0006] Further, the housing part of the bidirectional clutch adopts a circular groove-shaped member, and a perforation is opened at the center of the groove bottom of the housing part. The groove opening end of the housing part is bolted and fixed below the planetary gear reducer. The rotating shaft passes through the perforation of the housing part. In addition, a rotating body is arranged in the groove of the housing part. The rotating body is a plate-shaped member, and its center is coaxially connected and driven with the rotating shaft. The edge contour of the rotating body is circular and has a gap with the inner wall of the groove of the housing part. At the same time, two W-shaped notches are symmetrically machined at the edge of the rotating body. Each W-shaped notch is composed of two L-shaped notches with intersecting long arm ends. Each L-shaped notch is equipped with a self-locking module. The self-locking module includes a cylindrical roller and an electromagnet. The cylindrical roller is placed at the corner of the L-shaped notch, and a spring is supported between the corner of the L-shaped notch and the side wall of the cylindrical roller. The electromagnet is embedded and fixed inside the short arm of the L-shaped notch. When the electromagnet is turned on, it magnetically attracts and fixes the cylindrical roller to form an unlocked state with a gap between the cylindrical roller and the inner wall of the groove of the housing part. When the electromagnet is turned off, the cylindrical roller is elastically supported on the inner wall of the groove of the housing part by the spring to form a locked state.

[0007] Further, a power source is embedded inside the rotating body to supply power to the electromagnet, and the electromagnet is controlled to be switched on and off in a wireless manner.

[0008] Further, the rotating shaft is detachably assembled and connected to the rotating body.

[0009] Further, a special-shaped hole is formed in the center of the rotating body, and the assembling end of the rotating shaft is processed into a shaft rod section with a cross section matching that of the special-shaped hole.

[0010] Further, the special-shaped hole is a circular segment-shaped hole.

[0011] Further, the rotating shaft and the rotating body are integrally formed.

[0012] Further, a plurality of hand connection holes are uniformly processed on the edge of the end parallel connection joint, and a connection part is circumferentially arranged on the outer side wall of the upper end of the bottom shell, and a plurality of arm connection holes are uniformly processed on the connection part.

[0013] Compared with the prior art, the beneficial effects of the present invention are as follows: According to the connection and movement requirements of the anthropomorphic electromechanical robotic arm in the hand and the arm, a three-degree-of-freedom series-parallel hybrid wrist is designed based on a two-way active clutch and a brake. The pitching and yawing motions are realized by the forward and reverse telescoping of two linear motors. On the basis of pitching and yawing, a twisting motion is added through a rotating motor combined with a housing mechanism. The series-parallel hybrid method is centrally designed in the housing mechanism to reasonably control the axial dimension. The rotating motor of the series mechanism provides one degree of freedom, and the two linear motors of the parallel mechanism provide two degrees of freedom, improving the control decoupling performance, reducing the control complexity, facilitating the design of the control program, and realizing the three-degree-of-freedom motion output. The linear motor has a self-locking function, and the output of the rotating motor realizes the two-way active unlocking and locking braking of the twist through a two-way clutch. Therefore, all three degrees of freedom can be powered off and held, effectively improving the flexibility of the robot wrist, and having the advantages of large stiffness, stable structure, and strong load-bearing capacity. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 is an external view schematic diagram of the three-degree-of-freedom robot wrist of the present invention;

[0015] Figure 2 is an isometric view of the internal structure of the three-degree-of-freedom robot wrist of the present invention;

[0016] Figure 3 is a front view schematic diagram of the internal structure of the three-degree-of-freedom robot wrist of the present invention;

[0017] Figure 4 is Figure 3 a front view schematic diagram omitting the frame and the top and bottom rotating seats;

[0018] Figure 5 It is a schematic bottom view of the internal structure of the two-way clutch in the present invention.

[0019] In the figure: 1. Bottom shell; 2. Top shell; 3. Frame; 4. Top rotating seat; 5. Rotating motor; 6. Planetary gear reducer; 7. Two-way clutch; 8. Rotating shaft; 9. Bottom rotating seat; 10. Linear motor; 11. Ball hinge; 12. Connecting piece; 13. End parallel joint; 14. Universal joint; 15. Top positioning screw; 16. Hand connecting hole; 17. Bottom positioning screw; 18. Arm connecting hole; 19. Motor positioning screw; 20. Pin 1; 21. Pin 2; 22. Rotating body; 23. Cylindrical roller; 24. Electromagnet. Detailed implementation manners

[0020] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0021] As Figures 1 to 5 shown, a three-degree-of-freedom robot wrist with two-way active clutch and braking functions includes a bottom shell 1, a top shell 2, a frame 3, a top rotating seat 4, a rotating motor 5, a planetary gear reducer 6, a two-way clutch 7, a rotating shaft 8, a bottom rotating seat 9, a linear motor 10, a ball hinge 11, a connecting piece 12, an end parallel joint 13, a universal joint 14, a top positioning screw 15, a hand connecting hole 16, a bottom positioning screw 17, an arm connecting hole 18, a motor positioning screw 19, a pin 1 20, a pin 2 21, a rotating body 22, a cylindrical roller 23, and an electromagnet 24.

[0022] Combined with Figure 1 shown, the outside of the robot wrist is provided with a housing mechanism composed of two cylindrical shells, namely a bottom shell 1 and a top shell 2, which are arranged coaxially.

[0023] The upper end of the bottom shell 1 is rotatably connected to the lower end of the top shell 2 through a bearing. Among them, a connecting portion is also circumferentially arranged on the outer side wall of the upper end of the bottom shell 1, and a plurality of arm connecting holes 18 are uniformly processed on the connecting portion for the assembly of the robot arm and the bottom shell 1; the upper end of the top shell 2 extends out with an end parallel joint 13. The main body of the end parallel joint 13 is disc-shaped and a plurality of hand connecting holes 16 are uniformly processed on its edge for the assembly of the robot hand and the end parallel joint 13.

[0024] Combined with Figures 2 to 4As shown, a control mechanism for the robot wrist is provided inside the housing mechanism to achieve the three-degree-of-freedom motion output of the wrist, including a rotary motor 5, a planetary gear reducer 6, a bidirectional clutch 7, and two linear motors 10.

[0025] A bottom rotating seat 9 is fixedly arranged inside the bottom housing 1 through bottom positioning screws 17. A top rotating seat 4 is arranged at the lower end inside the top housing 2. The top rotating seat 4 and the bottom rotating seat 9 are rotatably connected through a bearing. Both of them adopt a hollow ring structure to reserve an installation space for the planetary gear reducer 6 and the bidirectional clutch 7. A frame 3 is fixedly arranged at the center position of the upper surface of the top rotating seat 4. The upper end of the frame 3 is fixedly connected to the top housing 2 through top positioning screws 15. The center position of the bottom of the disc of the end parallel joint 13 is installed at the top of the frame 3 through a universal joint 14. The universal joint 14 allows movement in two directions of pitch and yaw.

[0026] The rotary motor 5 is longitudinally fixed inside the bottom of the frame 3 through motor positioning screws 19. The planetary gear reducer 6 is bolted longitudinally below the frame 3. The output shaft of the rotary motor 5 passes through the frame 3 and is connected to the input end of the planetary gear reducer 6, reducing the speed and increasing the output torque at the same time.

[0027] The bidirectional clutch 7 is bolted longitudinally below the planetary gear reducer 6. A rotating shaft 8 is coaxially arranged on the bidirectional clutch 7. The upper end of the rotating shaft 8 is connected to the output end of the planetary gear reducer 6, and the lower end of the rotating shaft 8 is fixedly connected to the bottom rotating seat 9 through a connecting pin. When the bidirectional clutch 7 is in the unlocked state, it allows the rotary motor 5 to control the rotating shaft 8 to rotate in both forward and reverse directions through the planetary gear reducer 6, so as to drive the relative rotation of the top rotating seat 4 and the bottom rotating seat 9, which is equivalent to the relative rotation of the top housing 2 and the bottom housing 1, and is also equivalent to the relative rotation of the end parallel joint 13 and the bottom housing 1 (since the frame 3 and the top rotating seat 4 are an integral structure and the end parallel joint 13 is installed at the top of the frame 3, the relative rotation of the top rotating seat 4 is accompanied by the end parallel joint 13), thus realizing the twisting action of the robot hand and the robot arm, which is one degree of freedom in one direction; while when the bidirectional clutch 7 is in the locked state, the forward and reverse rotations of the rotating shaft 8 are restricted, so that the robot hand and the robot arm no longer produce a twisting action.

[0028] The two linear motors 10 are arranged in parallel on both sides of the rotary motor 5 and are eccentrically arranged with the end parallel joint 13. The bottoms of the two linear motors 10 are respectively connected to the corresponding positions on both sides of the bottom of the frame 3 through spherical hinges 11. An n-shaped connecting beam is integrally arranged at the eccentric position at the bottom of the disc of the end parallel joint 13. The telescopic ends of the two linear motors 10 are respectively connected to both ends of the n-shaped connecting beam through connectors 12. Among them, the lower end of the connector 12 is hinged to the telescopic end of the linear motor 10 through a first pin 20, and the upper end of the connector 12 is hinged to the end of the n-shaped connecting beam through a second pin 21, and the first pin 20 and the second pin 21 are vertically arranged. When the telescopic movements of the two linear motors 10 are synchronized, the end parallel joint 13 performs a pitching motion relative to the frame 3, which is a degree of freedom in one direction; when the two linear motors 10 perform telescopic movements in opposite directions, the end parallel joint 13 performs a yaw motion relative to the frame 3, which is a degree of freedom in one direction. Thus, through the mutual cooperation of the twisting motion, the pitching motion and the yaw motion, the three-degree-of-freedom motion output of the robot wrist is realized.

[0029] Combined Figure 5 As shown, the robot wrist adopts an optimized two-way clutch 7. Its housing part is a circular groove-shaped member and a perforation is provided at the center of the groove bottom. The notch end of the housing part is bolted to the lower part of the planetary gear reducer 6, and the rotating shaft 8 passes through the perforation of the housing part. On this basis, a rotating body 22 is arranged in the groove of the housing part. The rotating body 22 is a plate-shaped member and its center is coaxially connected and driven with the rotating shaft 8. The edge contour of the rotating body 22 is circular and there is a gap with the inner wall of the groove of the housing part. At the same time, two W-shaped notches are symmetrically processed at the edge of the rotating body 22. Each of the W-shaped notches is composed of two L-shaped notches with intersecting long arm ends, and each of the L-shaped notches is equipped with a self-locking module. The self-locking module includes a cylindrical roller 23 and an electromagnet 24. The cylindrical roller 23 is placed at the corner of the L-shaped notch, and a spring is supported between the corner of the L-shaped notch and the side wall of the cylindrical roller 23. The electromagnet 24 is embedded and fixed inside the short arm of the L-shaped notch.

[0030] The specific working principle is described as follows:

[0031] When the rotating shaft 8 needs to rotate, the electromagnet 24 is turned on to magnetically fix the cylindrical roller 23 so that there is a gap between it and the inner wall of the groove of the housing part, which is in the unlocked state. At this time, the rotating shaft 8 does not produce a restrictive effect and allows the rotating motor 5 to rotate forward and backward according to requirements;

[0032] When the rotating shaft 8 does not need to rotate, the electromagnet 24 is turned off, and the cylindrical roller 23 is elastically supported on the inner wall of the groove of the housing part by a spring. At this time, regardless of the rotational movement tendency of the rotating body 22 in the forward or reverse direction, two diagonal cylindrical rollers 23 will be squeezed by the long arm ends of the corresponding L-shaped notches, increasing the friction between the cylindrical roller 23 and the inner wall of the groove of the housing part. At this time, the acting force of the cylindrical roller 23 is almost perpendicular to the contact surface, forming a self-locking, thereby restricting the rotation of the rotating body 22 and the rotating shaft 8.

[0033] Among them, the rotating body 22 and the rotating shaft 8 can be made into one body or connected by detachable assembly. For example, a special-shaped hole is machined in the center of the rotating body 22, and a shaft rod section with a cross-section matching the special-shaped hole is machined at the assembly end of the rotating shaft 8, so as to insert and position the rotating shaft 8 and the rotating body 22. For the convenience of machining the rotating shaft 8, the special-shaped hole is preferably a circular notch hole, so that only one plane needs to be machined on the side wall of the rotating shaft 8.

[0034] In addition, in view of the problem that if the electromagnet 24 is externally connected to a power supply through a wire, it is easy to cause wire entanglement during the rotation of the rotating body 22, a power supply can be embedded inside the rotating body 22 to supply power to the electromagnet 24, and the electromagnet 24 is controlled to be switched in a wireless manner.

[0035] Through the above optimization design of the two-way clutch 7, there is no distinction between the driving shaft and the driven shaft, greatly streamlining the number of parts and the axial thickness of the clutch, making the overall structure simpler and the volume smaller, which helps to further reduce the axial dimension of the robot wrist and provides technical support for the size optimization of the robot wrist.

[0036] For those skilled in the art, it is obvious that the present invention is not limited to the details of the above exemplary embodiments, and the present invention can be implemented in other forms without departing from the spirit or basic characteristics of the present invention. Therefore, from any point of view, the embodiments should be regarded as exemplary and non-limiting. The scope of the present invention is defined by the appended claims rather than the above description. Therefore, all changes falling within the meaning and scope of the equivalent conditions of the claims are intended to be included in the present invention. Any reference signs in the claims should not be regarded as limiting the claimed claims.

[0037] In addition, it should be understood that although this specification is described according to embodiments, not every embodiment only contains an independent technical solution. This narrative way of the specification is only for clarity. Those skilled in the art should regard the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A three-degree-of-freedom robot wrist with bidirectional active clutch and braking functions, comprising a frame (3), a terminal parallel joint (13) and two linear motors (10), wherein the terminal parallel joint (13) is disc-shaped and its bottom center is mounted on the top of the frame (3) through a universal joint (14), the two linear motors (10) are arranged in parallel and eccentrically arranged with the terminal parallel joint (13), the bottom ends of the two linear motors (10) are respectively connected to the bottom of the frame (3) through ball joints (11), an n-shaped connecting beam is arranged at an eccentric position at the bottom of the terminal parallel joint (13), and the telescopic ends of the two linear motors (10) are respectively hinged to the two ends of the n-shaped connecting beam through connecting pieces (12), characterized in that: The robot wrist further comprises a bottom shell (1), a top shell (2), a top rotating seat (4), a rotating motor (5), a planetary gear reducer (6), a bidirectional clutch (7) and a bottom rotating seat (9); the bottom shell (1) and the top shell (2) are two cylindrical shells arranged coaxially and rotatably connected; the bottom rotating seat (9) is fixed inside the bottom shell (1); the top rotating seat (4) is arranged at the lower end inside the top shell (2) and is rotatably connected to the bottom rotating seat (9); the top rotating seat (4) and the bottom rotating seat (9) both adopt an annular structure; the bottom of the frame (3) is fixed at the center position of the upper surface of the top rotating seat (4); The upper end of the frame (3) is connected and fixed to the top shell (2), and the end parallel joint (13) extends out of the top shell (2). The rotating motor (5) is longitudinally fixed to the bottom of the frame (3), and the planetary gear reducer (6) is longitudinally fixed below the frame (3). The output shaft of the rotating motor (5) passes through the frame (3) and is connected to the input end of the planetary gear reducer (6). The two-way clutch (7) is longitudinally fixed below the planetary gear reducer (6). The two-way clutch (7) is coaxially provided with a rotating shaft (8). The housing part of the two-way clutch (7) adopts a circular groove-shaped component and a through hole is opened at the center of the groove bottom. The notch end of the housing part is bolted to the planetary gear reducer. The rotating shaft (8) is disposed below the speed reducer (6), and the rotating shaft (8) passes through the through hole of the housing part. In addition, a rotating body (22) is arranged in the groove of the housing part. The rotating body (22) is a plate-shaped component and its center is coaxially connected with the rotating shaft (8) for transmission. The edge profile of the rotating body (22) is circular and has a gap with the inner wall of the groove of the housing part. At the same time, two W-shaped notches are symmetrically processed on the edge of the rotating body (22). Each of the W-shaped notches is composed of two L-shaped notches intersecting at the long arm end. Each of the L-shaped notches is equipped with a self-locking module. The self-locking module includes a cylindrical roller (23) and an electromagnet (24). The cylindrical roller (23) is placed at the corner of the L-shaped notch. The cylindrical roller (23) is fixed at the corner of the L-shaped notch and supported by a spring between the corner of the L-shaped notch and the side wall of the cylindrical roller (23). The electromagnet (24) is embedded and fixed inside the short arm of the L-shaped notch. When the electromagnet (24) is turned on, the cylindrical roller (23) is magnetically fixed so that a gap is left between it and the inner wall of the groove of the housing part to form an unlocked state. When the electromagnet (24) is turned off, the cylindrical roller (23) is elastically supported on the inner wall of the groove of the housing part through the spring to form a locked state. In the unlocked and locked states, the forward and reverse rotations of the rotating shaft (8) are respectively allowed and restricted. The upper end of the rotating shaft (8) is connected to the output end of the planetary gear reducer (6), and the lower end of the rotating shaft (8) is connected and fixed to the bottom rotating seat (9).

2. A three-degree-of-freedom robot wrist with two-way active clutch and braking functions according to claim 1, characterized in that: A power source is embedded in the rotating body (22) to supply power to the electromagnet (24), and the electromagnet (24) is switched on and off in a wireless manner.

3. A three-degree-of-freedom robot wrist with two-way active clutch and braking functions according to claim 2, characterized in that: The rotating shaft (8) is detachably assembled and connected to the rotating body (22).

4. A three-degree-of-freedom robot wrist with two-way active clutch and braking functions according to claim 3, characterized in that: A special-shaped hole is provided at the center of the rotating body (22), and the assembly end of the rotating shaft (8) is processed into a shaft section whose cross section matches the special-shaped hole.

5. A three-degree-of-freedom robot wrist with two-way active clutch and braking functions according to claim 4, characterized in that: The special-shaped hole is a circular hole.

6. The three-degree-of-freedom robot wrist with two-way active clutch and braking functions according to claim 2, characterized in that: The rotating shaft (8) and the rotating body (22) are made as one piece.

7. The three-degree-of-freedom robot wrist with two-way active clutch and braking functions according to claim 1, characterized in that: A plurality of hand connection holes (16) are evenly processed on the edge of the terminal parallel joint (13), and a connection portion is circumferentially arranged on the outer side wall of the upper end of the bottom shell (1), and a plurality of arm connection holes (18) are evenly processed on the connection portion.

Images