Joints and Robots

Abstract

The present invention discloses a joint and a robotic arm, wherein the joint comprises: a joint ball head; a wrapping piece, wherein the wrapping piece comprises a first wrapping layer and a second wrapping layer, wherein the first wrapping layer wraps around the outside of the joint ball head, and the second wrapping layer is arranged on the outside of the first wrapping layer and defines a chamber between the first wrapping layer and the joint cover, wherein a portion of the joint cover extends into the chamber and the second wrapping layer wraps around a portion of the joint cover, so that the joint cover and the joint ball head are arranged at intervals, wherein the wrapping piece is a deformable material piece, and the joint cover can rotate relative to the joint ball head and drive the wrapping piece to deform. According to the joint of the embodiment of the present invention, the joint cover can realize a large range of rotation with multiple degrees of freedom relative to the joint ball head, and when wrapped by the wrapping piece, it can provide good buffering and absorb impact when subjected to external impact, and restore its original shape after impact, thereby protecting the joint cover and the joint ball head.

Description

Technical Field

[0001] The present invention relates to the field of robotics technology, and in particular to a joint and a robotic arm. Background Art

[0002] In the design of robotic arms, passive joints can be divided into single-degree-of-freedom joints and multi-degree-of-freedom joints according to the number of their degrees of freedom. Single-degree-of-freedom joints are rotating hinges, whose rotation is provided by bearings. Therefore, the rotation is stable and precise, and can withstand large axial loads. Three-degree-of-freedom joints include ball joints, universal joints, etc. The mechanism of the ball joint is that the ball cup holds the ball head, and the connection is provided by rigid components. Therefore, its rotation range is small and it is difficult to exceed 180 degrees, which in turn limits the range of motion of the robotic arm. The universal joint is essentially a series of multiple single-degree-of-freedom joints with a complex structure and a large dead weight. Therefore, there is valuable room for research on multi-degree-of-freedom joints. Summary of the invention

[0003] The present invention aims to solve at least one of the technical problems existing in the prior art. To this end, one object of the present invention is to provide a joint that can achieve a large range of rotation with multiple degrees of freedom.

[0004] The invention also provides a mechanical arm.

[0005] The joint according to the first aspect of the embodiment of the present invention includes: a joint ball head; a wrapping piece, the wrapping piece includes a first wrapping layer and a second wrapping layer, the first wrapping layer wraps around the outside of the joint ball head, the second wrapping layer is arranged on the outside of the first wrapping layer and defines a cavity between the second wrapping layer and the first wrapping layer; a joint cover, a part of the joint cover extends into the cavity and the second wrapping layer wraps around a part of the joint cover, so that the joint cover and the joint ball head are arranged at intervals, wherein the wrapping piece is a deformable material piece, the joint cover can rotate relative to the joint ball head and drive the wrapping piece to deform.

[0006] According to the joint of the embodiment of the present invention, a wrapping piece having a first wrapping layer and a second wrapping layer is provided, so that the first wrapping layer wraps the joint ball head and the second wrapping layer wraps the joint cover, thereby achieving the cooperation between the joint cover and the joint ball head; through the deformation of the wrapping piece, the joint cover can be rotated relative to the joint ball head, and by adjusting the relative size of the joint cover, the rotation range of the joint cover can be adjusted, thereby enabling the joint to achieve multi-degree-of-freedom and large-range rotation, solving the problems of small rotation range of traditional ball joints, complex structure and large self-weight of universal joints, etc.; and under the wrapping of the wrapping piece, when subjected to external impact, the deformation of the wrapping piece can provide good buffering, absorb the impact, and restore the original shape after the impact to protect the joint cover and the joint ball head; the joint can be used in various types of robots and robotic arms, provide stable rotation between different rigid components, have certain flexibility and impact resistance, and can adjust the rotation stiffness when liquid is injected into the chamber, and has very good application prospects in many fields such as human-machine collaboration, humanoid robotic arms, exoskeleton robots, medical rehabilitation, disaster relief, etc.

[0007] According to the joint of an embodiment of the present invention, the joint cover includes a mounting portion and a first connecting portion, the mounting portion can extend into the cavity and the second wrapping portion wraps the mounting portion, and the side surface of the mounting portion facing the joint ball head is a part of a spherical surface; the first connecting portion is arranged in the middle of the mounting portion and extends in a direction away from the joint ball head, and the first connecting portion is suitable for connecting an external structural member.

[0008] In some examples, the chamber may be filled with a liquid.

[0009] In some examples, a liquid passage is provided in a middle portion of the connecting portion, and the liquid passage is communicated with the chamber to perfuse liquid into the chamber.

[0010] In some examples, the end of the first connecting portion away from the mounting portion has a liquid-passing joint, the liquid-passing joint is in communication with the liquid-passing channel, and the liquid-passing joint is suitable for connecting to an external connecting pipe.

[0011] In some examples, the second wrapping layer defines a first opening communicating with the chamber, the mounting portion blocks the first opening, and the first connecting portion extends out of the first opening.

[0012] In some examples, the wrapper defines a second opening opposite to the first opening, and the second connecting portion of the joint ball head can extend out of the second opening.

[0013] According to the joint of an embodiment of the present invention, the joint ball head includes a ball head body and a second connecting part, the first wrapping layer wraps the ball head body, the second connecting part is arranged on the outer surface of the ball head body and extends away from the center of the ball head body, and the second connecting part is suitable for connecting an external structural part.

[0014] According to the joint of the embodiment of the present invention, the first wrapping layer is bonded to the joint ball head, and the second wrapping layer is bonded to the joint cover.

[0015] The robotic arm according to the second aspect of the present invention comprises the joint according to the first aspect of the present invention. By adopting the above-mentioned joint, the rotation range is improved, and the robot arm has certain flexibility and impact resistance. When liquid is injected into the chamber, the rotation stiffness can be adjusted, and stable rotation can be provided between different rigid components. The overall structure is simple, the weight is small, and the cost is low.

[0016] Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The above and / or additional aspects and advantages of the present invention will become apparent and easily understood from the description of the embodiments in conjunction with the following drawings, in which:

[0018] Figure 1 is a visual structural diagram of a joint according to an embodiment of the present invention;

[0019] Figure 2 is another visual structural schematic diagram of a joint according to an embodiment of the present invention;

[0020] Figure 3 is along Figure 2 Sectional view along line AA;

[0021] Figure 4 is a visual structural schematic diagram of a joint cover according to an embodiment of the present invention;

[0022] Figure 5 is another visual structural schematic diagram of a joint cover according to an embodiment of the present invention;

[0023] Figure 6 is a cross-sectional view of a joint cover according to an embodiment of the present invention;

[0024] Figure 7 is a schematic structural diagram of a package according to an embodiment of the present invention;

[0025] Figure 8 is along Figure 7 Sectional view along line BB.

[0026] Reference numerals:

[0027] Joint 100,

[0028] Joint ball head 10, ball head body 11, second connecting part 12,

[0029] Package 20, first package layer 21, second package layer 22, chamber 23, first opening 24, second opening 25,

[0030] Joint cover 30 , mounting portion 31 , first connecting portion 32 , liquid passage 33 , liquid passage joint 34 . DETAILED DESCRIPTION

[0031] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and cannot be understood as limiting the present invention.

[0032] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. In addition, features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "multiple" means two or more.

[0033] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0034] Reference below Figure 1-Figure 8 A joint 100 according to an embodiment of the present invention is described.

[0035] like Figure 1-Figure 8As shown, a joint 100 according to an embodiment of the present invention includes: a joint ball head 10, a wrapping piece 20 and a joint cover 30, the wrapping piece 20 includes a first wrapping layer 21 and a second wrapping layer 22, the first wrapping layer 21 is wrapped around the outside of the joint ball head 10, the second wrapping layer 22 is arranged on the outside of the first wrapping layer 21, a chamber 23 is defined between the second wrapping layer 22 and the first wrapping layer 21, a portion of the joint cover 30 can extend into the chamber 23, the second wrapping layer 22 wraps a portion of the joint cover 30, and the joint cover 30 and the joint ball head 10 are arranged at intervals, thereby forming a relatively sealed cavity between the second wrapping layer 22 and the first wrapping layer 21, and between the inner wall surface of the joint cover 30 and the outer wall surface of the first wrapping layer 21, thereby constituting the entire joint 100.

[0036] Among them, the wrapping piece 20 is a deformable material piece, such as a flexible piece or an elastic piece. The joint cover 30 can rotate relative to the joint ball head 10. The deformation of the wrapping piece 20 facilitates the rotation of the joint cover 30, while ensuring the stability of the overall structure when the joint cover 30 moves. Both the joint ball head 10 and the joint cover 30 can be wrapped by the wrapping piece 20. When the joint 100 collides with other objects, the deformation of the wrapping piece 20 can absorb the impact of the collision, thereby ensuring safety during movement. It also has a certain degree of flexibility to meet the application of human-computer interaction.

[0037] It can be understood that when the joint cover 30 rotates relative to the joint ball head 10, the joint 100 can have three-degree-of-freedom rotation capabilities and a large range of continuous rotation capabilities. For example, when the angle of the joint cover 30 is 90 degrees, the theoretical maximum rotation angle that can be achieved on the joint ball head 10 around the axis perpendicular to the paper plane is 270 degrees, which is much larger than the 220-degree range of motion of the human shoulder joint, thereby achieving a large range of rotation. At the same time, the overall size is compact, the structure is simple, the cost is low, and the rotation is stable, which is suitable for application in the development of robotic arms and bionic robots.

[0038] According to the joint 100 of the embodiment of the present invention, a wrapping piece 20 having a first wrapping layer 21 and a second wrapping layer 22 is provided, so that the first wrapping layer 21 wraps the joint ball head 10, and the second wrapping layer 22 wraps the joint cover 30, so as to achieve the cooperation between the joint cover 30 and the joint ball head 10; through the deformation of the wrapping piece 20, the joint cover 30 can be rotated relative to the joint ball head 10, and the rotation range of the joint cover 30 can be adjusted by adjusting the relative size of the joint cover 30, so that the joint 100 can achieve a large range of rotation with multiple degrees of freedom, which solves the problem that the traditional ball joint has a small rotation range and a complex universal joint structure. and when wrapped in the wrapping piece 20, when impacted by the outside world, the deformation of the wrapping piece 20 can provide good cushioning, absorb the impact, and restore its original shape after the impact, thereby protecting the joint cover 30 and the joint ball head 10; the joint 100 can be used in various types of robots and robotic arms, providing stable rotation between different rigid components, having certain flexibility and impact resistance, and the rotational stiffness can be adjusted when liquid is injected into the chamber 23, and has very good application prospects in many fields such as human-machine collaboration, humanoid robotic arms, exoskeleton robots, medical rehabilitation, disaster relief, etc.

[0039] According to one embodiment of the present invention, the joint cover 30 includes a mounting portion 31 and a first connecting portion 32, the mounting portion 31 can extend into the chamber 23, the second wrapping portion wraps the mounting portion 31, and the surface of the mounting portion 31 facing the joint ball head 10 is a part of the spherical surface, so that the mounting portion 31 is opposite to the outer surface of the joint ball head 10, and the mounting portion 31 can rotate relative to the joint ball head 10 without interference. It can be understood that when the joint cover 30 rotates relative to the joint ball head 10, the mounting portion 31 can contact and fit with the first wrapping layer 21 to form a stable rotational motion.

[0040] like Figure 3 As shown, the first connection portion 32 is arranged in the middle of the mounting portion 31, and the first connection portion 32 extends in a direction away from the joint ball head 10. The center of the mounting portion 31 is located on the central axis of the first connection portion 32, and the center of the joint ball head 10 is also located on the central axis of the first connection portion 32. The extension direction of the first connection portion 32 (as shown in FIG. Figure 3 The up-down direction shown in the figure is the radial direction of the joint ball head 10. The first connecting portion 32 can be connected to an external structural component, so that the joint 100 can be modularized, which is convenient for connection and coordination with external structural components.

[0041] In some examples, the chamber 23 may be filled with liquid, and the liquid here may be oil. When there is oil in the chamber 23, on the one hand, the friction between the joint cover 30 and the joint ball head 10 can be reduced to make the movement smoother, thereby improving its application value; on the other hand, after the liquid is injected, the air in the chamber 23 is discharged and the chamber 23 is sealed, and the oil in the chamber 23 can provide a larger vertical load for the joint 100, that is, the vertical load capacity is provided by the negative pressure of the liquid in the chamber 23, so that when the joint 100 is subjected to axial tension, it can withstand a larger axial tension, and the joint cover 30 and the joint ball head 10 are not easy to separate; on the other hand, by changing the amount of liquid in the chamber 23, the rotational stiffness and axial stiffness of the joint 100 can also be changed; in addition, it can also withstand a certain impact, and even produce an effect similar to "dislocation" of the human body to protect the joint cover 30 and the joint ball head 10.

[0042] It can be understood that the wrapping piece 20 has a certain deformability. When the amount of liquid in the chamber 23 is small, the inner boundary of the wrapping piece 20 is closer to the outer boundary of the joint cover 30 and the joint ball head 10, and is not easy to deform. The rotational stiffness and axial stiffness of the joint 100 are large; when the amount of liquid in the chamber 23 is large, the wrapping piece 20 is more likely to deform, and the rotational stiffness and axial stiffness of the joint 100 are small, thereby changing the amount of liquid in the chamber 23 and changing the rotational stiffness and axial stiffness of the joint 100; when the joint 100 is subjected to axial tension, the joint cover 30 has a tendency to move away from the joint ball head 10, and the chamber 23 has a tendency to increase in volume. The liquid pressure in the chamber 23 is reduced, which can generate a greater suction force on the joint cover 30 to resist the axial tension, making it difficult for the joint cover 30 and the joint ball head 10 to separate, avoiding the movement of the joint cover 30 or the joint ball head 10, ensuring that the joint can withstand a larger axial tension, and improving the stability of the structure.

[0043] Of course, other liquids can be injected into the chamber 23, or no liquid can be injected, and the joint cover 30 can rotate freely on the joint ball head 10 without causing any essential changes to the joint 100, which should also fall within the scope of protection of the present invention. By injecting liquid, the joint 100 can have the characteristics of variable rotational stiffness on the basis of a wide range of rotation with three degrees of freedom, so as to form a stable position output and force output.

[0044] In some examples, a liquid passage 33 is provided in the middle of the connection portion, and the liquid passage 33 is connected to the chamber 23, so that liquid can be poured into the chamber 23. The provision of the liquid passage 33 allows the amount of liquid in the chamber 23 to be changed, and the rotational stiffness can be dynamically adjusted according to different tasks to be performed, thereby achieving both rigidity and flexibility.

[0045] Among them, the liquid passage 33 includes two liquid passages, one liquid passage 33 is a liquid inlet channel, and the other liquid passage 33 is a liquid outlet channel. According to the task to be performed, liquid can be introduced into the chamber 23 through the liquid inlet channel, and excess liquid in the chamber 23 can be discharged through the liquid outlet channel to achieve dynamic adjustment.

[0046] In some examples, the end of the first connecting portion 32 away from the mounting portion 31 has a liquid-passing joint 34, which is connected to the liquid-passing channel 33. The liquid-passing joint 34 can be connected to an external connecting tube. The liquid-passing joint 34 can be designed as a pagoda head, so that a standard silicone tube can be easily used to connect the chamber 23, so that an oil injection pump can be used to control the amount of oil in the chamber 23.

[0047] like Figure 8 As shown, in some examples, the second wrapping layer 22 defines a first opening 24, the first opening 24 is connected to the chamber 23, the mounting portion 31 blocks the first opening 24, the first connecting portion 32 extends out of the first opening 24, and the second wrapping layer 22 can be bonded and matched with the outer wall surface of the mounting portion 31, thereby achieving the installation of the joint cover 30 on the second wrapping layer 22, wherein the maximum central angle of the arc on the mounting portion 31 passing through its center is the opening angle of the joint cover 30, when the opening angle is small, the joint cover 30 can rotate relative to the joint ball head 10 at a large angle range, and when the opening angle is large, the joint cover 30 can rotate relative to the joint ball head 10 at a small angle.

[0048] like Figure 8 As shown, in some examples, the wrapping member 20 is defined with a second opening 25, and the second opening 25 is positioned opposite to the first opening 24. For example, the lower end of the second wrapping layer 22 is connected to the first wrapping layer 21, and the upper end of the second wrapping layer 22 is spaced apart from the first wrapping layer 21. The second opening 25 is located at the lower end of the wrapping member 20, and the second opening 25 is defined by the first wrapping layer 21 and the second wrapping layer 22. The second connecting portion 12 of the joint ball head 10 can extend out of the second opening 25, thereby allowing the second connecting portion 12 to extend out and connect to other rods, so that the joint 100 can be modularized.

[0049] like Figure 2 and Figure 3 As shown, according to some embodiments of the present invention, the joint ball head 10 includes a ball head body 11 and a second connecting portion 12, the first wrapping layer 21 wraps the ball head body 11, the ball head body 11 is located in the joint cover 30, the ball head body 11 can rotate relative to the joint cover 30, and the second connecting portion 12 is arranged on the outer surface of the ball head body 11, as shown in FIG. Figure 3 As shown, the second connecting portion 12 is arranged in the middle of the ball head body 11, and the second connecting portion 12 extends in a direction away from the center of the ball head body 11. The center of the joint ball head 10 is located on the central axis of the second connecting portion 12. The extending direction of the second connecting portion 12 (as shown in FIG. Figure 3 The up-down direction) is the radial direction of the joint ball head 10. The second connecting portion 12 can be connected to an external structural component, so that the joint 100 can be modularized, which is convenient for connection and coordination with external structural components.

[0050] like Figure 3 and Figure 8 As shown, the wrapping piece 20 can be a silicone rubber piece, and the wrapping piece 20 is a rotating body structure. The first wrapping layer 21 wraps the joint ball head 10, and the upper part of the second wrapping layer 22 wraps the joint cover 30, and the remaining part is naturally attached to the joint ball head 10. In order to make the wrapping piece 20 more closely attached to the joint cover 30 and the joint ball head 10, an adhesive can be used in the connecting part so that the first wrapping layer 21 is bonded to the joint ball head 10, and the second wrapping layer 22 is bonded to the joint cover 30.

[0051] When the joint cover 30 rotates on the joint ball head 10, except for the bonded part, the remaining part of the second wrapping layer 22 will be deformed as the joint cover 30 rotates, but will not hinder the rotation of the joint. At the same time, silicone rubber flexible material is used, and the silicone rubber flexible layer wraps the entire joint. When it is impacted by the outside world, the silicone rubber flexible material can provide good cushioning, absorb impact, and restore its original shape after impact to protect the internal rigid part.

[0052] Of course, the first wrapping layer 21 and the joint ball head 10 can also be connected in other ways, such as fixed connection through fasteners, integral injection molding, etc. The second wrapping layer 22 and the joint cover 30 can also be connected in other ways, such as fixed connection through fasteners, integral injection molding, etc. The wrapping piece 20 can also be made of other flexible deformable materials, which are not specifically limited here.

[0053] The robotic arm according to the embodiment of the present invention includes the joint 100 according to the embodiment of the present invention. By adopting the above-mentioned joint 100, the rotation range is improved, and it has certain flexibility and impact resistance. The rotation stiffness can be adjusted when liquid is injected into the chamber 23, and stable rotation can be provided between different rigid components. The overall structure is simple, the dead weight is small, and the cost is low. Among them, the joint 100 according to the present invention adopts a modular design, and the movements between each joint 100 are independent of each other. The robotic arm can include multiple joints 100, and multiple joints 100 can be connected in series to achieve a larger range of motion.

[0054] Other structures and operations of the robot arm according to the embodiment of the present invention are known to those skilled in the art and will not be described in detail here. The up-down direction, left-right direction and front-back direction are based on the up-down direction, left-right direction and front-back direction shown in the figure.

[0055] In the description of the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply means that the first feature is higher in level than the second feature.

[0056] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "illustrative embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0057] Although the embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the claims and their equivalents.

Claims

1. A joint, characterized in that: include: Joint ball head; A wrapping member, the wrapping member comprising a first wrapping layer and a second wrapping layer, the first wrapping layer wrapping the outside of the joint ball head, the second wrapping layer being arranged outside the first wrapping layer and defining a chamber between the second wrapping layer and the first wrapping layer; a joint cover, a portion of which extends into the chamber and the second wrapping layer wraps a portion of the joint cover, so that the joint cover and the joint ball head are arranged at intervals, Wherein, the wrapping piece is a deformable material piece, and the joint cover can rotate relative to the joint ball head and drive the wrapping piece to deform; The joint cover comprises a mounting portion and a first connecting portion, the mounting portion can extend into the chamber and the second wrapping layer wraps the mounting portion, and a surface of the mounting portion facing the joint ball head is a part of a spherical surface; the first connecting portion is arranged in the middle of the mounting portion and extends in a direction away from the joint ball head, and the first connecting portion is suitable for connecting an external structural member; The chamber may be filled with liquid; The middle part of the connecting part is provided with a liquid passage, and the liquid passage is communicated with the chamber so as to perfuse liquid into the chamber; The second wrapping layer defines a first opening communicating with the chamber, the lower end of the second wrapping layer is connected to the first wrapping layer, the wrapping piece defines a second opening opposite to the first opening, the second opening is jointly defined by the first wrapping layer and the second wrapping layer, and a relatively sealed cavity is formed between the second wrapping layer and the first wrapping layer, and between the inner wall surface of the joint cover and the outer wall surface of the first wrapping layer.

2. The joint according to claim 1, characterized in that An end of the first connecting portion away from the mounting portion is provided with a liquid-passing joint, the liquid-passing joint is communicated with the liquid-passing channel, and the liquid-passing joint is suitable for being connected to an external connecting pipe.

3. The joint according to claim 1, characterized in that The mounting portion blocks the first opening and the first connecting portion extends out of the first opening.

4. The joint according to claim 3, characterized in that The second connection portion of the joint ball head can extend out of the second opening.

5. The joint according to claim 1, characterized in that The joint ball head includes a ball head body and a second connecting portion, the first wrapping layer wraps the ball head body, the second connecting portion is arranged on the outer surface of the ball head body and extends in a direction away from the center of the ball head body, and the second connecting portion is suitable for connecting an external structural member.

6. The joint according to claim 1, characterized in that The first wrapping layer is bonded to the joint ball head, and the second wrapping layer is bonded to the joint cover.

7. A robotic arm, characterized in that: Comprising a joint according to any one of claims 1-6.

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