A mechanical wrist joint based on flexible tether drive
By using multi-degree-of-freedom ball hinge and flexible tether to simulate the tendon driving technology, the problems of large size, heavy weight and inconvenient movement of traditional mechanical wrist joints are solved, and lightweight, compact and good flexible control effects are achieved.
Patent Information
- Application Number
- CN202111589024.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2021-12-23
- Publication Date
- 2025-04-25
- Estimated Expiration
- 2041-12-23
AI Technical Summary
Traditional mechanical wrist joints restrict the use and promotion of prosthetic limbs due to their large size, heavier weight and inconvenient movement.
The mechanical wrist joint driven by a flexible tether is adopted to simulate the human tendon through a multi-degree of freedom ball hinge and a flexible tether, so as to achieve accurate control of the ball hinge and achieve good flexibility control effect.
It realizes lightweight, compact and convenient installation of mechanical wrist joints, has good flexible control capabilities, and improves the convenience of use and promotion potential of prosthetic limbs.
Smart Images
Figure CN114176851B_ABST
Abstract
Description
Technical Field
[0001] The invention relates to a mechanical wrist joint, in particular to a mechanical wrist joint driven by a flexible tether. Background Art
[0002] Currently, there are very few cost-effective prostheses available on the market for people with limb disabilities, and most of them are decorative. In addition, most current prostheses use a single-degree-of-freedom motor combined with a mechanical mechanism to achieve multi-degree-of-freedom rotation of the wrist. The large number of mechanical transmission mechanisms makes the overall size of the wrist larger, heavier, and inconvenient to move, which limits the use and promotion of prostheses. Although mechanical wrist-band prosthetic technology has developed in the direction of multi-degree-of-freedom and high-precision since the 1970s, overall, there are currently few mature commercial wrist-band prosthetic hands. From the perspective of design focus, most research and design on prostheses tend to be decorative, with less consideration of functionality. Summary of the invention
[0003] The present invention takes a mechanical wrist joint as the background, and aims to provide a mechanical wrist joint driven by a flexible tether to address the shortcomings of traditional mechanical wrist joints, such as large size, heavy weight, and inconvenient movement. The mechanical wrist joint uses a ball joint with multiple degrees of freedom. At the same time, multiple flexible tethers are used to simulate human tendons to send motion commands, and precise control of the ball joint is achieved by retracting and releasing the tethers, ultimately achieving good compliant control of the mechanical wrist joint.
[0004] To achieve the above object, the technical solution of the present invention is as follows:
[0005] The present invention comprises a manipulator, a tether retractable module and a multi-degree-of-freedom ball joint module; the wrist joint of the manipulator is connected to the multi-degree-of-freedom ball joint module, the multi-degree-of-freedom ball joint module is connected to the tether retractable module, the tether retractable module drives and controls the output of the multi-degree-of-freedom ball joint module, so that the multi-degree-of-freedom ball joint module controls the wrist joint of the manipulator.
[0006] The multi-degree-of-freedom ball joint module comprises a ball joint sleeve, a ball joint base, an output rod, an external self-locking module and an internal ball joint module;
[0007] The lower surface of the ball joint base is fixedly connected to the tether retraction and extension module, the ball joint sleeve is installed on the ball joint base through the built-in ball joint module, the upper part of the ball joint sleeve is fixedly installed with an external self-locking module, the external self-locking module is fixedly installed with an output rod, the output rod is coaxially fixedly connected to the wrist joint of the manipulator, the external self-locking module and the built-in ball joint module are matched by threads, and the built-in ball joint module and the external self-locking module are fixedly connected by threads, so that the ball joint sleeve is axially self-locking; a plurality of tether through holes arranged at equal intervals along the circumference are opened in the ball joint base, and the tether retraction and extension module is fixedly connected to the external self-locking module after passing through the tether through holes.
[0008] The built-in ball joint module includes a ball joint rod and a ball joint rod top cover;
[0009] The middle part of the ball joint sleeve is provided with a mounting through hole in the vertical direction, the diameter of the upper part of the mounting through hole is larger than the diameter of the lower part of the mounting through hole, and the middle part of the mounting through hole is provided with a funnel-shaped arc hole, one end of the ball joint rod is provided with a spherical shape, and the other end of the ball joint rod is provided with a rod shape, and the rod-shaped end of the ball joint rod passes through the mounting through hole from above and is connected with the ball joint base, and the spherical end of the ball joint rod is just stuck in the funnel-shaped arc hole in the middle part of the mounting through hole, so that the ball joint rod is fixedly installed in the middle part of the ball joint sleeve; a ball joint rod top cover is also provided at the upper part of the mounting through hole near the spherical end of the ball joint rod, and the ball joint rod top cover is in contact with the spherical end of the ball joint rod; a blind hole is also provided at the top of the spherical end of the ball joint rod, and the lower part of the external self-locking module passes through the ball joint rod top cover and is arranged in the blind hole and is threadedly connected with the spherical end of the ball joint rod, thereby realizing axial self-locking of the ball joint sleeve.
[0010] The external self-locking module includes a locking motor, a transmission pin, a self-locking screw, an inner sleeve and a ball joint top cover;
[0011] The ball joint top cover is fixedly installed on the ball joint sleeve, and an output rod is fixedly installed on the ball joint top cover. The lower surface of the ball joint top cover is fixedly connected to the tether retracting and releasing module. A top cover through hole is opened in the middle of the ball joint top cover, and a self-locking screw and an inner sleeve are installed in the top cover through hole. The inner sleeve is coaxially sleeved outside the self-locking screw, and a locking motor is arranged at the upper end of the self-locking screw. The output shaft of the locking motor is coaxially fixedly connected to the upper end of the self-locking screw through a transmission pin, and the lower end of the self-locking screw is threadedly matched with the upper part of the built-in ball joint module. The locking motor is driven so that the self-locking screw coaxially connected to the output shaft of the locking motor rotates downward, and then the lower end of the self-locking screw is fixedly connected to the upper part of the built-in ball joint module through a thread, thereby realizing axial self-locking of the ball joint sleeve.
[0012] The tether retracting and releasing module comprises a connecting shaft, a tensioning wheel, a hub motor, a tether base, a motor bracket and a tether;
[0013] The multi-degree-of-freedom ball joint module is connected to the tether base through a connecting shaft. Multiple motor brackets are installed on the tether base at equal intervals along the circumference. A hub motor is installed on each motor bracket. A tension sensor is set on the tension wheel to measure the tension of the tether. One end of each tether is wound around the hub motor through the tension wheel, and the other end of each tether is fixedly connected to the multi-degree-of-freedom ball joint module.
[0014] The beneficial effects of the present invention are:
[0015] 1. Compared with the traditional mechanical wrist joint, the present invention uses a high-reliability multi-degree-of-freedom ball joint, so the mechanical wrist joint is light in weight, small in size and easy to install.
[0016] 2. Compared with the traditional mechanical wrist joint, the rear end of the present invention adopts a tether to simulate the human tendon signal, with a high degree of coupling, which can achieve good flexible control of the mechanical wrist joint.
[0017] 3. The present invention has ingenious structural design, is easy to manufacture, and is easy to implement in engineering.
[0018] 4. The center of mass of the multi-degree-of-freedom spherical joint of the present invention is stable, the rotor is evenly stressed, and it is easier to drive. BRIEF DESCRIPTION OF THE DRAWINGS
[0019] Figure 1 It is one of the three-dimensional diagrams of the mechanical wrist joint of the present invention;
[0020] Figure 2 This is the second three-dimensional diagram of the mechanical wrist joint of the present invention;
[0021] Figure 3 It is a schematic diagram of a multi-degree-of-freedom spherical joint module of the present invention;
[0022] Figure 4 is a cross-sectional view of the multi-degree-of-freedom spherical joint of the present invention;
[0023] Figure 5 is a schematic diagram of a tether retracting and releasing module of the present invention;
[0024] In the figure: 1. ball joint rod, 2. ball joint sleeve, 3. locking motor, 4. ball joint base, 5. ball joint rod top cover, 6. ball joint rod nut, 7. transmission pin, 8. self-locking screw, 9. inner sleeve, 10. output rod, 11. tether hole, 12. connecting screw, 13. connecting shaft, 14. tensioning wheel, 15. hub motor, 16. tether base, 17. motor bracket, 18. tether, 19. hub motor housing, 20. manipulator, 21. ball joint top cover. DETAILED DESCRIPTION
[0025] The present invention will be further described below in conjunction with the accompanying drawings and specific implementations.
[0026] like Figure 1 and Figure 2 As shown, the present invention includes a manipulator 20, a tether retractable module, and a multi-degree-of-freedom ball joint module; the wrist joint of the manipulator 20 is connected to the multi-degree-of-freedom ball joint module, and the multi-degree-of-freedom ball joint module is connected to the tether retractable module, and the drive of the tether retractable module controls the output of the multi-degree-of-freedom ball joint module, so that the multi-degree-of-freedom ball joint module controls the wrist joint of the manipulator 20.
[0027] The hub motor in the tether retraction and extension module rotates, driving the tether connected to the other end on the ball joint top cover 21 to be retracted and extended. At the same time, the tension sensor installed on the tensioning wheel in the tether retraction and extension module monitors the tension of each tether in real time. By adjusting the retraction and extension of the tether by the hub motor, different posture changes of the output rod can be achieved.
[0028] like Figure 3 and Figure 4 As shown, the multi-degree-of-freedom ball joint module includes a ball joint sleeve 2, a ball joint base 4, an output rod 10, an external self-locking module and an internal ball joint module;
[0029] The lower surface of the ball joint base 4 is fixedly connected to the tether retractable module, the ball joint sleeve 2 is installed on the ball joint base 4 through the built-in ball joint module, the upper part of the ball joint sleeve 2 is fixedly installed with an external self-locking module, and the external self-locking module is fixedly installed with an output rod 10, the output rod 10 is coaxially fixedly connected to the wrist joint of the manipulator 20, the external self-locking module and the built-in ball joint module are matched by threads, and the built-in ball joint module and the external self-locking module are fixedly connected by threads, then the ball joint sleeve 2 is axially self-locking, otherwise, the ball joint sleeve 2 is not axially self-locking; the ball joint base 4 is provided with a plurality of tether through holes 11 arranged at equal intervals along the circumference, in a specific implementation, there are 3 through holes 11, that is, the angle between two adjacent through holes 11 is 120°, and the multiple tethers 18 of the tether retractable module are fixedly connected to the external self-locking module after passing through the corresponding tether through holes 11.
[0030] The built-in ball joint module includes a ball joint rod nut 6, a ball joint rod 1 and a ball joint rod top cover 5;
[0031] A mounting through hole is provided in the middle of the ball joint sleeve 2 in the vertical direction. The diameter of the upper portion of the mounting through hole is larger than the diameter of the lower portion of the mounting through hole and the middle portion of the mounting through hole is set as a funnel-shaped arc hole. One end of the ball joint rod 1 is set as a ball, and the other end of the ball joint rod 1 is set as a rod. The rod-shaped end of the ball joint rod 1 passes through the mounting through hole from above and is connected to the ball joint base 4 through the ball joint rod nut 6. Specifically, a base through hole is provided in the middle of the ball joint base 4. The rod-shaped end of the ball joint rod 1 passes through the base through hole and is fixedly connected to the ball joint rod nut 6 through a thread, so that the ball joint rod 1 is installed on the ball joint base 4. The rod-shaped end of the ball joint rod 1 can move along the tether direction (i.e., axial direction), but does not rotate circumferentially. The spherical end of the ball joint rod 1 is just stuck in the funnel-shaped arc hole in the middle of the mounting through hole, so that the ball joint rod 1 is fixedly installed in the middle of the ball joint sleeve 2; a ball joint rod top cover 5 is also provided at the upper part of the mounting through hole close to the spherical end of the ball joint rod 1, and the ball joint rod top cover 5 is in contact with the spherical end of the ball joint rod 1; a blind hole is also provided on the top of the spherical end of the ball joint rod 1, and the lower end of the self-locking screw 8 at the bottom of the external self-locking module passes through the ball joint rod top cover 5 and is arranged in the blind hole and threadedly connected with the spherical end of the ball joint rod 1, thereby realizing axial self-locking of the ball joint sleeve 2.
[0032] The external self-locking module includes a locking motor 3, a transmission pin 7, a connecting screw 12, a self-locking screw 8, an inner bushing 9 and a ball joint top cover 21;
[0033] The ball joint top cover 21 is fixedly mounted on the ball joint sleeve 2 by means of a connecting screw 12. The ball joint sleeve 2 is spherical with a flat top. An output rod 10 is fixedly mounted on the ball joint top cover 21. The lower surface of the ball joint top cover 21 is fixedly connected to one end of multiple tethers 18 of the tether retracting and releasing module. A top cover through hole is opened in the middle of the ball joint top cover 21. A self-locking screw 8 and an inner sleeve 9 are installed in the top cover through hole. The inner sleeve 9 is coaxially sleeved outside the self-locking screw 8. The self-locking screw 8 and the inner sleeve 9 are threadedly connected. A locking motor 3 is arranged at the upper end of the self-locking screw 8. The output shaft of the locking motor 3 is connected through a transmission The movable pin 7 is coaxially fixedly connected to the upper end of the self-locking screw 8, and the lower surface of the inner sleeve 9 is in close contact with the upper surface of the ball joint rod top cover 5; a motor mounting hole is opened in the output rod 10, and the locking motor 3 is arranged in the motor mounting hole; the lower end of the self-locking screw 8 is threadedly matched with the upper part of the built-in ball joint module, and the locking motor 3 is driven so that the self-locking screw 8 coaxially connected to the output shaft of the locking motor 3 rotates downward, and then the lower end of the self-locking screw 8 is threadedly fixedly connected to the ball joint rod top cover 5 and the ball joint rod 1 on the upper part of the built-in ball joint module, thereby realizing axial self-locking of the ball joint sleeve 2.
[0034] The locking motor 3 is running, and the transmission pin 7 drives the self-locking screw 8 to rotate in the axial inner hole of the inner sleeve 7. The self-locking screw 8 rotates and moves up and down along the axial direction of the inner sleeve 7, thereby driving the lower end of the self-locking screw 8 to be inserted into the ball joint rod 1 to achieve locking control. When locking is required, the locking motor 3 drives the self-locking screw 8 downward and inserts it into the blind hole at the top of the ball joint rod 1 to achieve locking; when unlocking is required, the locking motor 3 performs the opposite movement. The upper and lower limits of the output displacement of the motor are adjusted by controlling the distance between the initial position of the lower end of the self-locking screw 8 and the bottom surface of the blind hole in the top of the ball joint rod 1.
[0035] like Figure 5 As shown, the tether retracting and releasing module includes a connecting shaft 13, a tensioning wheel 14, a hub motor 15, a tether base 16, a motor bracket 17, a hub motor housing 19 and a tether 18;
[0036] The multi-degree-of-freedom ball joint module is connected to the tether base 16 through a connecting shaft 13, which is located at the center of the tether base 16. A plurality of motor brackets 17 are installed on the tether base 16 at equal intervals along the circumference, and a hub motor 15 is installed on each motor bracket 17. A hub motor housing 19 is provided outside each hub motor 15. A tension sensor is provided on the tension wheel 14 to measure the tension of the tether 18. One end of each tether 18 is wound around the hub motor 15 through the tension wheel 14, and the other end of each tether 18 is fixedly connected to the multi-degree-of-freedom ball joint module; specifically, the other end of each tether passes through the tether through hole 11 of the ball joint base 4 and is fixedly connected to the ball joint top cover 21 of the external self-locking module. In the specific implementation, there are three hub motors 15 and three tethers 18. The rotation of the hub motor 15 realizes the retraction and extension of the tether 18. The retraction and extension process of the tether 18 is similar to the contraction and relaxation process of the tendon of the human body. The pressure sensor installed on the tensioning wheel 14 has a signal output, thereby realizing the tether-controlled rotation of the multi-degree-of-freedom ball joint and realizing the multi-posture of the output rod 10 of the ball joint.
[0037] The working process of the present invention is as follows:
[0038] After the locking motor is running, the transmission pin drives the self-locking screw to rotate in the axial inner hole of the inner sleeve. The self-locking screw rotates and moves up and down along the axial direction of the inner sleeve, thereby driving the lower end of the self-locking screw to insert into the ball hinge rod to achieve locking control. When locking is required, the locking motor drives the self-locking screw downward and inserts it into the blind hole at the top of the ball hinge rod to achieve locking. When unlocking is required, the locking motor can move in the opposite direction. After self-locking, compared with before self-locking, the output rod connected to the piezoelectric ball motor will not move with the stretching of the tether, so that the wrist joint can be fixed in a certain position, which is convenient for the manipulator to lift heavy objects.
[0039] The tether is wound around the hub motor through the tensioning wheel. During the movement, the tether is always kept in a tensioned state. The tension sensor on the tensioning wheel measures the tension and outputs a signal. The three hub motors can rotate independently without being affected. The contraction and relaxation of the tether are achieved through the rotation of the hub motor, simulating the contraction and relaxation process of human tendons. At the same time, the three hub motors move independently of each other without being affected. The tension sensors installed on the tensioning wheel are measured by different tension values from the tether, and the tension of the tether is changed by the rotation of the hub motor. When the wrist needs to move, one of the tethers is contracted by the rotation of the hub motor, and the tension becomes larger. The remaining tethers are relaxed by the rotation of the hub motor in the opposite direction, and the tension becomes smaller. Since the tether is connected to the lower end of the ball joint top cover and the ball joint sleeve is fixed at the lower end of the ball joint top cover, the contraction and relaxation of the tether can drive the ball joint top cover to move in the contraction direction of the tether.
Claims
1. A mechanical wrist joint driven by a flexible tether, characterized in that: It comprises a manipulator (20), a tether retractable module, and a multi-degree-of-freedom ball joint module; the wrist joint of the manipulator (20) is connected to the multi-degree-of-freedom ball joint module, the multi-degree-of-freedom ball joint module is connected to the tether retractable module, the drive of the tether retractable module controls the output of the multi-degree-of-freedom ball joint module, so that the multi-degree-of-freedom ball joint module controls the wrist joint of the manipulator (20); The multi-degree-of-freedom ball joint module comprises a ball joint sleeve (2), a ball joint base (4), an output rod (10), an external self-locking module and an internal ball joint module; The lower surface of the ball joint base (4) is fixedly connected to the tether retractable module, the ball joint sleeve (2) is installed on the ball joint base (4) via the internal ball joint module, an external self-locking module is fixedly installed on the upper part of the ball joint sleeve (2), an output rod (10) is fixedly installed on the external self-locking module, the output rod (10) is coaxially fixedly connected to the wrist joint of the manipulator (20), the external self-locking module and the internal ball joint module are matched by threads, and the internal ball joint module and the external self-locking module are fixedly connected by threads, so that the ball joint sleeve (2) is axially self-locking; a plurality of tether through holes (11) arranged at equal intervals along the circumference are opened in the ball joint base (4), and the tether retractable module is fixedly connected to the external self-locking module after passing through the tether through holes (11); The built-in ball joint module comprises a ball joint rod (1) and a ball joint rod top cover (5); The middle part of the ball joint sleeve (2) is provided with a mounting through hole in the vertical direction, the diameter of the upper part of the mounting through hole is larger than the diameter of the lower part of the mounting through hole, and the middle part of the mounting through hole is arranged as a funnel-shaped arc hole, one end of the ball joint rod (1) is arranged as a ball, and the other end of the ball joint rod (1) is arranged as a rod, and the rod-shaped end of the ball joint rod (1) passes through the mounting through hole from above and is connected to the ball joint base (4), and the ball-shaped end of the ball joint rod (1) is just stuck in the funnel-shaped arc hole in the middle part of the mounting through hole, so that The ball hinge rod (1) is fixedly mounted in the middle of the ball hinge sleeve (2); a ball hinge rod top cover (5) is also arranged on the upper part of the mounting through hole near the spherical end of the ball hinge rod (1), and the ball hinge rod top cover (5) is in contact with the spherical end of the ball hinge rod (1); a blind hole is also opened at the top of the spherical end of the ball hinge rod (1), and the lower part of the external self-locking module passes through the ball hinge rod top cover (5) and is arranged in the blind hole and is threadedly connected to the spherical end of the ball hinge rod (1), thereby realizing axial self-locking of the ball hinge sleeve (2); The external self-locking module comprises a locking motor (3), a transmission pin (7), a self-locking screw (8), an inner bushing (9) and a ball joint top cover (21); The ball joint top cover (21) is fixedly mounted on the ball joint sleeve (2), an output rod (10) is fixedly mounted on the ball joint top cover (21), a lower surface of the ball joint top cover (21) is fixedly connected to the tether retracting and releasing module, a top cover through hole is opened in the middle of the ball joint top cover (21), a self-locking screw (8) and an inner sleeve (9) are installed in the top cover through hole, the inner sleeve (9) is coaxially sleeved outside the self-locking screw (8), a locking motor (3) is arranged at the upper end of the self-locking screw (8), and a locking motor (3) is arranged at the upper end of the self-locking screw (8). The output shaft of the dead motor (3) is coaxially fixedly connected to the upper end of the self-locking screw (8) via a transmission pin (7), and the lower end of the self-locking screw (8) is threadedly matched with the upper part of the built-in ball joint module. The dead motor (3) is driven so that the self-locking screw (8) coaxially connected to the output shaft of the dead motor (3) rotates downward, and the lower end of the self-locking screw (8) is threadedly fixedly connected to the upper part of the built-in ball joint module, thereby realizing axial self-locking of the ball joint sleeve (2); The tether retracting and releasing module comprises a connecting shaft (13), a tensioning wheel (14), a hub motor (15), a tether base (16), a motor bracket (17) and a tether (18); The multi-degree-of-freedom spherical joint module is connected to the tether base (16) via a connecting shaft (13); a plurality of motor brackets (17) are installed at equal intervals along the circumference of the tether base (16); a wheel hub motor (15) is installed on each motor bracket (17); a tension sensor is provided on the tension wheel (14) for measuring the tension of the tether (18); one end of each tether (18) is wound around the wheel hub motor (15) via the tension wheel (14); and the other end of each tether (18) is fixedly connected to the multi-degree-of-freedom spherical joint module.
Citation Information
Patent Citations
Mechanical wrist structure device
CN109048988A
Spherical hinge type multi-degree-of-freedom traveling wave type ultrasonic ball motor
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