Rope-driven three-degree-of-freedom high-rigidity spherical wrist joint

Abstract

The present application relates to a kind of high stiffness spherical wrist joints of three degrees of freedom of rope drive, including base, wrist platform, multiple connecting rod groups and winding shaft;Connecting rod group is arranged around wrist platform, one end of connecting rod group is connected with wrist platform, and connecting rod group includes multiple connecting rod members connected in sequence;Winding shaft is installed on base, the other end of connecting rod group is connected with winding shaft, and winding shaft is rotated by the moment difference generated by driving line wound on winding shaft, and winding shaft drives wrist platform to rotate by connecting rod group;Power can be transmitted from a long distance by using rope drive, keep the overall size of wrist structure miniaturization, realize the dexterity and safety of agile robot arm.

Description

Technical Field

[0001] This invention belongs to the field of robotic arms, specifically relating to a rope-driven, three-degree-of-freedom, high-stiffness spherical wrist joint. Background Technology

[0002] There are many types of robotic arm wrists, each with different principles and structures, expanding the functionality of robotic arms and enabling them to adapt to different work requirements. To accomplish more complex and precise tasks, and to achieve greater human-like performance, robotic arm wrists are developing towards parallel connections, compact structures, and simpler principles. Currently, robotic arm wrists mainly achieve transmission through traditional mechanical transmission and pneumatics, but this still results in increased overall wrist size and increased robotic arm inertia, hindering the dexterity and safety of truly agile robotic arms. Summary of the Invention

[0003] Aimed at at least in solving one of the technical problems existing in the prior art, the present invention provides a rope-driven three-degree-of-freedom high-stiffness spherical wrist joint, which is beneficial to achieving dexterity and safety of robotic arms.

[0004] A first aspect of the present invention provides a cable-driven, three-degree-of-freedom, high-stiffness spherical wrist joint, comprising:

[0005] Base;

[0006] Wrist platform;

[0007] Multiple linkage groups are arranged around the wrist platform, one end of each linkage group is connected to the wrist platform, and each linkage group includes multiple connecting rods connected in sequence.

[0008] A winding shaft is mounted on the base, and the other end of the connecting rod assembly is connected to the winding shaft;

[0009] The winding shaft is driven to rotate by the torque difference generated by the drive wire wound on the winding shaft, and the winding shaft drives the wrist platform to rotate through the linkage assembly.

[0010] According to an embodiment of a first aspect of the present invention, the wrist platform is connected to the base via a universal joint.

[0011] According to an embodiment of a first aspect of the present invention, the wrist platform includes a first end face and a second end face, the second end face being connected to the universal joint, the first end face being smaller than the second end face, and an inclined rod connecting surface being provided between the first end face and the second end face.

[0012] According to an embodiment of a first aspect of the present invention, the plurality of connecting rods includes a first connecting rod, a second connecting rod, and a third connecting rod. One end of the first connecting rod is axially connected to the rod connecting surface, the other end of the first connecting rod is axially connected to one end of the second connecting rod, the other end of the second connecting rod is axially connected to one end of the third connecting rod, and the other end of the third connecting rod is connected to the winding shaft.

[0013] According to an embodiment of a first aspect of the present invention, the drive line includes an opening / closing line and a closing line, the opening / closing line and the closing line being wound on the winding shaft.

[0014] According to an embodiment of a first aspect of the present invention, the opening / closing line and the contraction line are wound around a driver, and the winding directions of the opening / closing line and the contraction line on the driver are opposite.

[0015] According to an embodiment of a first aspect of the present invention, the base is equipped with a pulley assembly for guiding the drive line from the driver to the winding shaft.

[0016] According to an embodiment of a first aspect of the present invention, the pulley assembly includes a first pulley and a second pulley, the first pulley being used to guide the opening / closing line from the driver to the winding shaft, and the second pulley being used to guide the closing line from the driver to the winding shaft.

[0017] According to an embodiment of the first aspect of the present invention, the number of linkage groups is three, and the angle between two adjacent linkage groups is 120 degrees.

[0018] According to a second aspect of the present invention, a robotic arm is provided with a cable-driven, three-degree-of-freedom, high-stiffness spherical wrist joint as described above.

[0019] The beneficial effects of this invention include: the ability to obtain the operating parameters of each servo motor based on the rotation angle of the wrist platform. The servo motors operate according to these parameters. Because the opening / closing and retraction lines are wound in opposite directions on the driver, they undergo opposite displacements, which are transmitted to the winding shaft via a pulley system, causing the winding shaft to rotate accordingly. The winding shaft drives the linkage assembly to rotate, and under the drive of the three linkage assemblies, the wrist platform rotates. Using rope drive allows power to be transmitted to a greater distance while ensuring the overall size of the wrist structure is not excessively large. Furthermore, the use of universal joints improves the rigidity of the spherical wrist, enabling both dexterity and safety in the agile robotic arm.

[0020] Furthermore, additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0021] Figure 1 This is a structural diagram of a rope-driven, three-degree-of-freedom, high-stiffness spherical wrist joint;

[0022] Figure 2 This is a structural diagram of the wrist platform;

[0023] Figure 3 This is a structural diagram of the connecting rod assembly.

[0024] Figure label:

[0025] 100 Base; 110 First Structural Plate; 120 Second Structural Plate;

[0026] 200 Wrist Platform; 210 First End Face; 220 Second End Face; 230 Rod Connection Surface; 240 Mounting Platform;

[0027] 300 Linkage; 310 First Link; 320 Second Link; 330 Third Link;

[0028] 400 winding spool; 410 spool mounting bracket; 420 bearing support bracket;

[0029] 500 pulley block; 510 first pulley; 520 second pulley;

[0030] 6 million universal joint. Detailed Implementation

[0031] The following will provide a clear and complete description of the concept, specific structure, and technical effects of the present invention in conjunction with the embodiments and accompanying drawings, so as to fully understand the purpose, solution, and effects of the present invention. It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other.

[0032] It should be noted that, unless otherwise specified, when a feature is referred to as "fixed" or "connected" to another feature, it can be directly fixed or connected to the other feature, or indirectly fixed or connected to the other feature. Furthermore, the descriptions of "upper," "lower," "left," "right," "top," and "bottom" used in this invention are only relative to the relative positional relationships of the various components of the invention in the accompanying drawings.

[0033] Furthermore, unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. The terminology used in this specification is for the purpose of describing particular embodiments only and not for limiting the invention. The term "and / or" as used herein includes any combination of one or more of the associated listed items.

[0034] It should be understood that although the terms first, second, third, etc., may be used in this disclosure to describe various elements, these elements should not be limited to these terms. These terms are only used to distinguish elements of the same type from one another. For example, without departing from the scope of this disclosure, a first element may also be referred to as a second element, and similarly, a second element may also be referred to as a first element.

[0035] Robotic arms have been widely used in industrial production and the robotics industry. To accomplish more complex and precise tasks, and to achieve greater human-like performance, robotic arm wrists are evolving towards parallel connections, compact structures, and simpler operating principles. Currently, robotic arm wrists primarily achieve power transmission through traditional mechanical transmission and pneumatic systems. However, this still leads to issues such as increased overall wrist size and increased robotic arm inertia, hindering the realization of dexterity and safety in agile robotic arms.

[0036] To address the aforementioned problems, embodiments of the present invention provide a rope-driven, three-degree-of-freedom, high-stiffness spherical wrist joint.

[0037] Reference Figure 1 The cable-driven three-degree-of-freedom high-stiffness spherical wrist joint includes: a base 100, a wrist platform 200, three linkages 300, three winding shafts 400, and a cable drive unit (not shown in the figure).

[0038] Three linkage groups 300 are arranged around the wrist platform 200, with one end of each linkage group 300 connected to the wrist platform 200. Each linkage group 300 includes multiple connecting rods connected in sequence. A winding shaft 400 is mounted on the base 100, and the other end of each linkage group 300 is connected to the winding shaft 400. A drive line is led out from the wire drive unit and wound around the winding shaft 400.

[0039] The base 100 is provided with a first structural plate 110 and a second structural plate 120, which are connected by a connecting plate, forming a cavity between the first structural plate 110 and the second structural plate 120. A weight-reducing hole is provided in the middle of the connecting plate, which can reduce the weight of the base 100 while maintaining the strength of the base 100.

[0040] The wrist platform 200 is connected to the base 100 via a universal joint 600, which enables the wrist platform 200 to rotate around the base 100 and makes the rotation of the wrist platform 200 more stable.

[0041] Universal joint 600 includes a cross rod and two U-shaped components. The two rods of the cross rod are connected perpendicularly to each other. Each U-shaped component includes two upright blocks and a base block. The two upright blocks are vertically positioned on both sides of the base block and are correspondingly arranged to form a U-shape. The two ends of one rod of the cross rod are respectively pivotally connected to the two upright blocks of one U-shaped component, allowing the one U-shaped component to rotate around the one rod of the cross rod. The two ends of the other rod of the cross rod are respectively pivotally connected to the two upright blocks of the other U-shaped component, allowing the other U-shaped component to rotate around the other rod of the cross rod. This allows the two U-shaped components to rotate in different directions around the cross rod, thus forming universal joint 600.

[0042] One of the hinges of the universal joint 600 is connected to the wrist platform 200, and the other hinge is connected to the first structural plate 110 of the base 100 via a connecting rod. The length of the connecting rod between the universal joint 600 and the base 100 is set according to the distance between the universal joint 600 and the base 100; when the distance between the universal joint 600 and the base 100 is close, the hinge of the universal joint 600 closest to the base 100 can be directly connected to the first structural plate 110 of the base 100.

[0043] In other embodiments, the universal joint 600 can also be a spherical universal joint 600 structure. The spherical universal joint 600 mainly consists of an inner ball joint, an outer ball joint, a universal rod, a bushing, and a retaining ring. Both the inner and outer ball joints are spherical; the inner ball joint is connected to the universal rod, and the outer ball joint is connected to the bushing, which is connected to the mechanical equipment. The retaining ring serves to fix and limit movement. The structure between the inner and outer ball joints is a spherical fit, allowing for omnidirectional rotation.

[0044] The rigidity of the spherical wrist is increased by using the Universal Joint 600, thereby improving the safety of the robotic arm.

[0045] Reference Figure 2 The wrist platform 200 includes a first end face 210 and a second end face 220. The second end face 220 is connected to the universal joint 600. The first end face 210 is smaller than the second end face 220. An inclined rod connecting surface 230 is provided between the first end face 210 and the second end face 220. The wrist platform 200 is frustum-shaped. The inclined rod connecting surface 230 facilitates the connection between the wrist platform 200 and the linkage assembly 300, and also facilitates the linkage assembly 300 in driving the wrist platform 200 to rotate.

[0046] A mounting platform 240 is connected to the first end face 210, and the mounting platform 240 is used to mount grippers and other robotic arm components.

[0047] Reference Figure 3For the linkage group 300, multiple linkages include a first linkage 310, a second linkage 320, and a third linkage 330. The first linkage 310, the second linkage 320, and the third linkage 330 are all arc-shaped, and the arc of the first linkage 310, the second linkage 320, and the third linkage 330 is the same. The length of the first linkage 310, the second linkage 320, and the third linkage 330 is determined by the distance between the wrist platform 200 and the winding shaft 400, and the arc of the first linkage 310, the second linkage 320, and the third linkage 330 is determined by the distance between the wrist platform 200 and the winding shaft 400.

[0048] One end of the first link 310 is axially connected to the rod connection surface 230, and the first link 310 can rotate around the wrist platform 200; the other end of the first link 310 is axially connected to one end of the second link 320, and the other end of the second link 320 is axially connected to one end of the third link 330, and the first link 310 and the second link 320 can rotate relative to each other, and the second link 320 can rotate around the third link 330; the other end of the third link 330 is connected to the winding shaft 400, and the third link 330 and the winding shaft 400 are relatively fixed.

[0049] The angle between two adjacent linkage groups 300 is 120 degrees.

[0050] The three linkages 300 can drive the wrist platform 200 to perform pitch, yaw and roll movements. The range of motion for the pitch and yaw degrees of freedom is ±60 degrees, and the range of motion for the roll degree of freedom is ±180 degrees.

[0051] Each winding shaft 400 corresponds one-to-one with each connecting rod assembly 300. The first structural plate 110 of the base 100 is provided with a shaft mounting member 410, through which the output shaft of the winding shaft 400 passes and connects to the third connecting rod 330. The second structural plate 120 of the base 100 is provided with a bearing support member 420, one end of which is connected to the second structural plate 120, and the other end of which is shaft-connected to the tail of the winding shaft 400. The bearing support member 420 serves to support the winding shaft 400. The shaft mounting member 410 and the bearing support member 420 together clamp the winding shaft 400, ensuring its stable installation.

[0052] The wire drive unit includes an opening / closing wire unit and a contraction wire unit. The drive wires leading from the opening / closing wire unit are opening / closing wires, and the drive wires leading from the contraction wire unit are contraction wires. Each winding shaft 400 corresponds to 6 drive wires, including 3 opening / closing wires and 3 contraction wires. The 3 opening / closing wires and 3 contraction wires are wound on one winding shaft 400. Each group of opening / closing wires and contraction wires is located on both sides of the winding shaft 400, with the 3 opening / closing wires located on the same side of the winding shaft 400 and the 3 contraction wires located on the other side of the winding shaft 400.

[0053] Although this embodiment uses an example of 6 drive lines, this does not limit the number of drive lines. In other embodiments, the number of drive lines can be different, such as 8 drive lines, including 4 opening and closing lines and 4 closing lines.

[0054] The drive line can be made of polyester fiber, which has high strength, high abrasion resistance, and high chemical resistance; or it can be made of metal wire, such as steel wire rope, which has high strength, high toughness and high tensile strength.

[0055] The line drive unit includes a driver, which is a servo motor. The opening and closing wires and the retraction wires are wound around the driver, and the winding directions of the opening and closing wires on the driver are opposite.

[0056] The servo motor can be installed in the cavity between the first structural plate 110 and the second structural plate 120 of the base 100.

[0057] Each winding spool 400 is provided with a corresponding pulley assembly 500. The pulley assembly 500 includes a first pulley 510 and a second pulley 520. The first pulley 510 is mounted on the first structural plate 110 and faces the second structural plate 120, and the second pulley 520 is mounted on the first structural plate 110 and faces the first mechanism plate. The first pulley 510 is used to guide the opening and closing wire from the driver to the winding spool 400, and the second pulley 520 is used to guide the closing wire from the driver to the winding spool 400.

[0058] Rope drives offer high flexibility, allowing the drive line to be arranged in any direction to adapt to different spatial and shape requirements. They also boast a wide speed range, with different speeds achievable by adjusting the rope tension and the angle around the axis. Rope drives are simple in structure, easy to manufacture and maintain, and offer high reliability. They have strong load-bearing capacity, as the drive line diameter and material can be selected to meet various load requirements. Furthermore, rope drives offer high transmission efficiency, which can be improved by selecting appropriate drive line materials to reduce friction. Rope drives are suitable for low-speed, high-torque transmission applications, exhibiting low noise and vibration.

[0059] Depending on the requirements, when the wrist joint is used in an agile robotic arm, the power source can be placed in the base 100 of the robotic arm due to the use of rope drive. This will reduce the inertia of the robotic arm and improve its dexterity and safety. The drive line can be routed from the winding shaft 400 end to the motor end through the pulley group 500 and the slide group.

[0060] The operating parameters of each servo motor are obtained based on the rotation angle of the wrist platform 200. The servo motors operate according to these parameters. Because the opening / closing and retraction lines are wound in opposite directions on the driver, they undergo opposite displacements, which are transmitted to the winding shaft 400 via the pulley group 500. This causes the winding shaft 400 to rotate accordingly, driving the linkage group 300 to rotate. Under the drive of the three linkage groups 300, the wrist platform 200 rotates. Using rope drive allows power to be transmitted from a distance while ensuring the overall size of the wrist structure is not excessive. The use of a universal joint 600 link improves the rigidity of the spherical wrist, enabling both dexterity and safety in the agile robotic arm.

[0061] Another embodiment of the present invention provides a robotic arm equipped with a cable-driven, three-degree-of-freedom, high-stiffness spherical wrist joint as described above. Grippers and other robotic arm components can be mounted on the spherical wrist joint.

[0062] This robotic arm can obtain the operating parameters of each servo motor based on the rotation angle of the wrist platform 200. The servo motors operate according to these parameters. Because the opening and closing lines and the retraction lines are wound in opposite directions on the driver, they undergo opposite displacements, which are transmitted to the winding shaft 400 via the pulley group 500. This causes the winding shaft 400 to rotate accordingly, driving the linkage group 300 to rotate. Under the drive of the three linkage groups 300, the wrist platform 200 rotates. Using rope drive allows power to be transmitted from a distance while ensuring the overall size of the wrist structure is not excessive. The use of a universal joint 600 link improves the rigidity of the spherical wrist, achieving both dexterity and safety for the agile robotic arm.

[0063] The above description is merely a preferred embodiment of the present invention. The present invention is not limited to the above-described embodiments. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of this disclosure, as long as they achieve the same technical effects, should be included within the scope of protection of this disclosure and fall under the protection scope of the present invention. Within the protection scope of the present invention, the technical solutions and / or implementation methods can have various modifications and variations.

Claims

1. A rope-driven, three-degree-of-freedom, high-stiffness spherical wrist joint, characterized in that, include: Base (100); Wrist platform (200); Multiple linkage groups (300) are arranged around the wrist platform (200), one end of each linkage group (300) is connected to the wrist platform (200), and each linkage group (300) includes multiple connecting rods connected in sequence. A winding shaft (400) is mounted on the base (100), and the other end of the connecting rod assembly (300) is connected to the winding shaft (400). The winding shaft (400) is driven to rotate by the torque difference generated by the drive line wound on the winding shaft (400), and the winding shaft (400) drives the wrist platform (200) to rotate through the linkage group (300); The drive line includes an opening and closing line and a contraction line, which are wound around the winding shaft (400). The opening and closing lines and the contraction lines are wound around the driver, and the winding directions of the opening and closing lines and the contraction lines on the driver are opposite.

2. The cable-driven, three-degree-of-freedom, high-stiffness spherical wrist joint according to claim 1, characterized in that, The wrist platform (200) is connected to the base (100) via a universal joint (600).

3. A rope-driven, three-degree-of-freedom, high-stiffness spherical wrist joint according to claim 2, characterized in that, The wrist platform (200) includes a first end face (210) and a second end face (220). The second end face (220) is connected to the universal joint (600). The first end face (210) is smaller than the second end face (220). An inclined rod connection surface (230) is provided between the first end face (210) and the second end face (220).

4. A rope-driven, three-degree-of-freedom, high-stiffness spherical wrist joint according to claim 3, characterized in that, The plurality of connecting links include a first connecting link (310), a second connecting link (320), and a third connecting link (330). One end of the first connecting link (310) is axially connected to the rod connecting surface (230), the other end of the first connecting link (310) is axially connected to one end of the second connecting link (320), the other end of the second connecting link (320) is axially connected to one end of the third connecting link (330), and the other end of the third connecting link (330) is connected to the winding shaft (400).

5. A cable-driven, three-degree-of-freedom, high-stiffness spherical wrist joint according to claim 1, characterized in that, The base (100) is equipped with a pulley assembly (500) for guiding the drive line from the driver to the winding shaft (400).

6. A cable-driven, three-degree-of-freedom, high-stiffness spherical wrist joint according to claim 5, characterized in that, The pulley assembly (500) includes a first pulley (510) and a second pulley (520), the first pulley (510) being used to guide the opening and closing line from the driver to the winding shaft (400), and the second pulley (520) being used to guide the closing line from the driver to the winding shaft (400).

7. A cable-driven, three-degree-of-freedom, high-stiffness spherical wrist joint according to claim 1, characterized in that, The number of linkage groups (300) is three, and the angle between two adjacent linkage groups (300) is 120 degrees.

8. A cable-driven, three-degree-of-freedom, high-stiffness spherical wrist joint according to claim 7, characterized in that, The wrist platform (200) is driven to pitch, yaw and roll by the three linkages (300), wherein the range of pitch and yaw freedom is ±60 degrees and the range of roll freedom is ±180 degrees.

9. A rope-driven, three-degree-of-freedom, high-stiffness spherical wrist joint according to claim 4, characterized in that, Each of the winding shafts (400) corresponds one-to-one with each of the connecting rod groups (300). The first structural plate (110) of the base (100) is provided with a shaft mounting member (410). The output shaft of the winding shaft (400) passes through the shaft mounting member (410) and is connected to the third connecting rod member (330). The second structural plate (120) of the base (100) is provided with a bearing support member (420). One end of the bearing support member (420) is connected to the second structural plate (120), and the other end of the bearing support member (420) is axially connected to the tail of the winding shaft (400). The bearing support member (420) plays the role of supporting the winding shaft (400). The shaft mounting member (410) and the bearing support member (420) together clamp the winding shaft (400), so that the winding shaft (400) is installed stably.

10. A robotic arm, characterized in that, The robotic arm is equipped with a rope-driven, three-degree-of-freedom, high-stiffness spherical wrist joint as described in any one of claims 1 to 9.

Images