Parallel robot driven arm connecting mechanism and parallel robot

Abstract

The application discloses a parallel robot driven arm connecting mechanism and a parallel robot. A first hanging part and a second hanging part are connected with two adjacent driven arms respectively. A containing cavity is arranged in a connecting body. A core shaft is arranged in the containing cavity in the axial direction of the connecting body. The core shaft is at least partially extended out of the containing cavity to connect the first hanging part. The connecting mechanism further comprises a first positioning member and a second positioning member arranged at two ends of the connecting body. The first hanging part is provided with a first positioning hole through which the core shaft passes. The core shaft is clamped with the first positioning member through the first positioning hole. The second hanging part is provided with a second positioning hole. The second positioning member is clamped with the connecting body through the second positioning hole. By arranging the components in the body, the overall rigidity is improved, and the external pollution is isolated. The external tension is converted into internal stable linear motion by the core shaft, and the path is clear and reliable. The positioning member clamping is adopted instead of the traditional threaded connection, so that the quick disassembly and convenient maintenance are realized, and the motion stability and safety of the parallel robot are improved.

Description

Technical Field

[0001] This application belongs to the field of parallel robots, specifically relating to a parallel robot follower arm connection mechanism and a parallel robot. Background Technology

[0002] Delta parallel robots, as a typical type of spatial multi-loop mechanism, are widely used in modern industry for sorting, packaging, and precision assembly due to their ability to achieve high-speed, high-precision translational motion on their moving platform. The structure of this type of robot typically includes an active arm and a driven arm, connected by ball joints to transmit motion and maintain the mechanism's degrees of freedom.

[0003] To ensure the stability and reliability of the mechanism during high-speed movement, especially to prevent the ball joint from disengaging due to inertia or vibration, a connection mechanism with a certain preload capacity is usually required between adjacent driven arms. Existing technologies often use elastic elements as the connection method, applying a continuous force to constrain the relative movement between the driven arms, thereby enhancing the holding force of the ball joint.

[0004] However, traditional flexible connection mechanisms still have certain limitations in terms of overall layout, external protection, installation methods, and long-term operational stability. For example, some structures are not adaptable to the external environment, occupy a large space which is not conducive to robot miniaturization, the disassembly and assembly process is complex and not conducive to maintenance, and the connection reliability is prone to decline under continuous vibration conditions. These factors, to some extent, limit the performance improvement and widespread application of Delta parallel robots in high-speed, high-reliability application scenarios.

[0005] Therefore, there is still a need in the field for a more rationally structured, easier-to-maintain, and more adaptable driven arm connection solution to further improve the overall performance of the robot. Utility Model Content

[0006] This application provides a parallel robot follower arm connection mechanism and a parallel robot, which solves at least one of the above-mentioned technical problems.

[0007] The technical solution adopted in this application is as follows: A parallel robot driven arm connection mechanism includes a connecting body and a first hook-on portion and a second hook-on portion located at both ends of the connecting body. The first hook-on portion and the second hook-on portion respectively connect two adjacent driven arms. The connecting body has a receiving cavity inside, and a mandrel is provided in the receiving cavity along the axial direction of the connecting body. The mandrel extends at least partially out of the receiving cavity to connect to the first hook-on portion. The connection mechanism also includes a first positioning member and a second positioning member respectively disposed at both ends of the connecting body. The first hook-on portion has a first positioning hole through which the mandrel passes, and the mandrel passes through the first positioning hole and engages with the first positioning member. The second hook-on portion has a second positioning hole, and the second positioning member passes through the second positioning hole and engages with the connecting body.

[0008] Preferably, the connecting body includes a sleeve, the sleeve is hollow to form the receiving cavity, and the two ends of the sleeve are provided with a first connection port and a second connection port respectively. The mandrel passes through the first connection port and the second positioning member passes through the second connection port.

[0009] Preferably, the first positioning element includes an elastic retaining ring; and / or, the second positioning element includes a plug.

[0010] Preferably, the connecting mechanism further includes an elastic element disposed within the receiving cavity, and an abutment portion is provided at the end of the spindle away from the first hook portion, and the elastic element abuts against the abutment portion.

[0011] Preferably, the elastic element includes a compression spring, which is wound around the outside of the mandrel. The first hook portion is subjected to force to drive the mandrel to move toward the first connection port to compress the compression spring.

[0012] Preferably, the receiving cavity includes a sealing cavity communicating with the second connection port, and the second positioning member extends into the sealing cavity from the second connection port.

[0013] Preferably, the sealing cavity further includes a wire retaining ring disposed between the second positioning member and the inner wall of the sleeve, the wire retaining ring being disposed circumferentially along the second positioning member.

[0014] Preferably, both the first and second attachment parts are provided with two hooks, and a clamping area for accommodating the driven arm is formed between the two hooks on the same side.

[0015] A parallel robot includes driven arms, with a connection mechanism as described in any of the preceding claims provided between two adjacent driven arms.

[0016] Due to the adoption of the above technical solution, the beneficial effects achieved by this application are as follows: By setting up a connecting body and its internal cavity, the form of traditional connecting mechanisms (such as exposed tension springs) is changed, and key transmission and elastic components are built into it, improving the overall integrity of the mechanism and avoiding the risk of exposed parts failing due to interference or collision under high-speed movement or complex working conditions. It provides a reliable protective environment for internal components, such as elastic elements and spindles that may be involved later, effectively isolating them from the intrusion of external contaminants such as dust and oil, thereby significantly improving the environmental adaptability and service life of the connecting mechanism.

[0017] This solution uses a spindle as the core transmission component and cleverly connects it with the coupling to achieve a highly efficient force transmission path. When the two driven arms tend to separate, the tension is transmitted to the spindle through the coupling, driving the spindle to move axially within the housing cavity. This transforms the external, unstable spatial tension into an internal, controllable, linear motion along a single axis, making the force state of the mechanism more defined and stable, and greatly improving the accuracy and reliability of motion transmission.

[0018] Furthermore, the design of the first and second positioning components replaces the drawbacks of traditional threaded connections, which require tools for tightening and are prone to loosening under vibration, through snap-fit ​​connections. This positioning component connection method (e.g., a combination of a further defined elastic retaining ring or plug and a wire retaining ring) typically achieves a one-click or snap-fit ​​fixation effect, making the installation and disassembly of the entire connection mechanism simple and quick, reducing maintenance time and costs. Simultaneously, the snap-fit ​​direction of the first and second positioning components, perpendicular to the movement direction of the spindle, ensures that the connection point will not loosen under long-term high-frequency, high-acceleration operation of the robot, avoiding potential safety accidents due to connection failure.

[0019] By integrating functional components within the connecting body, the radial and axial space occupancy is optimized, resulting in a significantly reduced volume compared to traditional structures such as parallel double springs. This provides greater freedom for the miniaturization and lightweight design of Delta parallel robots, allowing for a more compact robot body structure or the placement of more execution units within a limited space, thereby enhancing the product's versatility and market competitiveness. Attached Figure Description

[0020] The accompanying drawings, which are included to provide a further understanding of this application and form part of this application, illustrate exemplary embodiments and are used to explain this application, but do not constitute an undue limitation of this application. In the drawings: Figure 1 This is an assembly diagram of the connecting mechanism in one embodiment of the present invention; Figure 2 This is a schematic diagram of the external structure of the connecting mechanism in one embodiment of the present invention; Figure 3This is a schematic diagram of the internal structure of the connecting mechanism in one embodiment of the present invention.

[0021] Explanation of reference numerals in the attached figures: 1-Connecting body, 110-Sleeve, 111-First connecting port, 112-Second connecting port, 120-Accommodating cavity, 130-Blocking cavity; 2-First mounting part, 210-Hook; 3-Second coupling part; 4-Mandrel; 5-First positioning component, 510-Elastic retaining ring; 6-Second positioning component, 610-Plug; 7-Compression spring; 8-Steel wire retaining ring; 9-Driven boom. Detailed Implementation

[0022] To more clearly illustrate the overall concept of this application, a detailed explanation is provided below with reference to the accompanying drawings.

[0023] Many specific details are set forth in the following description to provide a thorough understanding of this application. However, this application may also be implemented in other ways different from those described herein. Therefore, the scope of protection of this application is not limited to the specific embodiments disclosed below. It should be noted that, unless otherwise specified, the embodiments of this application and the features thereof can be combined with each other.

[0024] Furthermore, it should be understood in the description of this application that the terms "top", "bottom", "inner", "outer", "axial", "radial", "circumferential", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0025] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a communication connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0026] In this application, unless otherwise expressly specified and limited, the "above" or "below" of the second feature can mean that the first and second features are in direct contact, or that the first and second features are in indirect contact through an intermediate medium. In the description of this specification, references to terms such as "an embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described can be combined in any suitable manner in one or more embodiments or examples.

[0027] This application provides a parallel robot slave arm connection mechanism, such as... Figures 1 to 3 As shown, the connection includes a connecting body 1 and a first hook-on portion 2 and a second hook-on portion 3 located at both ends of the connecting body 1. The first hook-on portion 2 and the second hook-on portion 3 are respectively connected to two adjacent driven arms 9. The connecting body 1 has a receiving cavity 120 inside, and a spindle 4 is provided in the receiving cavity 120 along the axial direction of the connecting body 1. The spindle 4 extends at least partially out of the receiving cavity 120 to connect to the first hook-on portion 2. The connection mechanism also includes a first positioning member 5 and a second positioning member 6 respectively located at both ends of the connecting body 1. The first hook-on portion 2 has a first positioning hole through which the spindle 4 passes, and the spindle 4 passes through the first positioning hole and engages with the first positioning member 5. The second hook-on portion 3 has a second positioning hole, and the second positioning member 6 passes through the second positioning hole and engages with the connecting body 1.

[0028] By setting up the connecting body 1 and its internal receiving cavity 120, the form of the traditional connecting mechanism (such as an exposed tension spring) is changed, and key transmission and elastic elements are built into it, which improves the overall integrity of the mechanism and avoids the risk of exposed parts failing due to interference or collision under high-speed movement or complex working conditions. It provides a reliable protective environment for internal components, such as the elastic elements and spindle 4 that may be involved later, effectively isolating the intrusion of external pollutants such as dust and oil, thereby significantly improving the environmental adaptability and service life of the connecting mechanism.

[0029] This design uses the spindle 4 as the core transmission component and cleverly connects it with the coupling part to achieve an efficient force transmission path. When the two driven arms 9 tend to separate, the tension is transmitted to the spindle 4 through the coupling part, driving the spindle 4 to move axially within the receiving cavity 120. This transforms the external, unstable spatial tension into an internal, controllable, linear motion along a single axis, making the force state of the mechanism more clear and stable, and greatly improving the accuracy and reliability of motion transmission.

[0030] Furthermore, the first positioning element 5 and the second positioning element 6 replace the drawbacks of traditional threaded connections, which require tools for tightening and are prone to loosening under vibration, with snap-fit ​​connections. This positioning element connection method (such as the combination of the elastic retaining ring 510 or the plug 610 and the wire retaining ring 8, as further defined in the following embodiments) can usually achieve the effect of plugging and snapping, making the installation and disassembly process of the entire connection mechanism simple and quick, reducing maintenance time and costs. At the same time, the snap-fit ​​direction of the first positioning element 5 and the second positioning element 6 is perpendicular to the movement direction of the spindle 4, ensuring that the connection point will not loosen under long-term high-frequency and high-acceleration operation of the robot, avoiding safety accidents that may be caused by connection failure.

[0031] By integrating functional components within the connecting body 1, the radial and axial space occupancy is optimized, resulting in a significantly reduced volume compared to traditional structures such as parallel double springs. This provides greater freedom for the miniaturization and lightweight design of the Delta parallel robot, allowing for a more compact robot body structure or the placement of more execution units within a limited space, thereby enhancing the product's versatility and market competitiveness.

[0032] In one embodiment, the connecting body 1 includes a sleeve 110, the sleeve 110 is hollow to form a receiving cavity 120, the two ends of the sleeve 110 are provided with a first connecting port 111 and a second connecting port 112, the mandrel 4 passes through the first connecting port 111, and the second positioning member 6 passes through the second connecting port 112.

[0033] In this embodiment, the connecting body 1 is configured as a sleeve 110 structure. The hollow cavity 120 within the sleeve provides a highly integrated and enclosed environment for the entire connecting mechanism, enhancing the overall rigidity and stability of the structure and effectively resisting the complex alternating stresses generated during high-speed robot movement. The first connecting port 111 and the second connecting port 112 at both ends of the sleeve 110 not only provide precise positioning references for the installation of the mandrel 4 and the second positioning component 6, but also play a precise guiding role in the movement of the mandrel 4, ensuring that the mandrel 4 maintains good coaxiality during reciprocating motion, avoiding uneven wear, and thus extending the service life of the mechanism. Furthermore, the sleeve 110 structure has excellent sealing performance, effectively preventing external dust, oil, and other impurities from entering the cavity 120, protecting the internal elastic elements and moving parts from contamination. This characteristic allows the connecting mechanism to adapt to harsher industrial environments. From a manufacturing perspective, the sleeve 110 structure is easy to mass-produce using conventional machining methods such as turning and broaching, ensuring dimensional accuracy and consistency, which is beneficial for quality control and large-scale application.

[0034] Preferably, the first positioning member 5 includes an elastic retaining ring 510; and / or, the second positioning member 6 includes a plug 610.

[0035] The first positioning component 5 is defined as an elastic retaining ring 510, which fully utilizes the advantage of the elastic retaining ring 510 as a standard component. Its installation process can be completed with just simple snap ring pliers, which facilitates quick assembly and disassembly. At the same time, the elastic retaining ring 510 achieves axial positioning through its own elastic deformation, and has good vibration and impact resistance. Even under long-term high-frequency vibration conditions, it can maintain a stable locking state, effectively avoiding the risk of traditional threaded connections loosening due to vibration.

[0036] The second positioning element 6 is defined as a plug 610. The fit between the plug 610 and the sleeve 110 can achieve a reliable end seal through interference fit or other fastening methods, further enhancing the airtightness of the receiving cavity 120. This combined positioning scheme not only ensures the reliability of the connection at both ends of the mechanism, but also realizes differentiated functional settings. The elastic retaining ring 510 at the first end facilitates frequent disassembly and maintenance, while the plug 610 at the second end provides stable end support. The two work together to construct a highly reliable connection that is threadless, prevents loosening, and is easy to maintain.

[0037] Furthermore, the connecting mechanism also includes an elastic element disposed in the receiving cavity 120, and an abutment portion is provided at the end of the spindle 4 away from the first hook portion 2, and the elastic element abuts against the abutment portion.

[0038] The elastic element, housed within the receiving cavity 120, engages with the abutment portion of the spindle 4, enabling the connecting mechanism to perform adjustment and damping / buffering functions. The elastic element provides the connecting mechanism with an inherent force sensing and response mechanism. When the driven arm 9 experiences relative displacement due to inertia or changes in external load during robot operation, this displacement is transmitted to the spindle 4 through the coupling portion, transforming into compression or release of the elastic element. The elastic element absorbs and stores energy through its elastic deformation, generating a corresponding counterforce. This achieves automatic adjustment and dynamic balance of the preload between the driven arms 9, effectively suppressing the instantaneous dislocation of the ball joint during high-acceleration motion. Simultaneously, as a highly efficient damping element, the elastic element rapidly attenuates the impact vibrations generated during robot start-up, stopping, or reversal, improving the motion stability and positioning accuracy of the moving platform. The design of embedding the elastic element within the receiving cavity 120 also optimizes the force transmission path, allowing the elastic force to act directly and efficiently on the driven arm 9 through the spindle 4 and the coupling portion, reducing energy loss in intermediate transmission links and improving the efficiency and accuracy of force transmission. This integrated elastic buffer mechanism provides more compliant and reliable motion protection for the entire robot system.

[0039] Preferably, the elastic element includes a compression spring 7, which is wound around the outside of the spindle 4. When the first hook part 2 is subjected to force, the spindle 4 moves toward the first connection port 111 to compress the compression spring 7.

[0040] The elastic element is specifically defined as a compression spring 7. As a mature and reliable elastic element, the compression spring 7 has unique advantages when working under compression. Its mechanical properties are stable, and the linearity of the force-displacement relationship is good, providing precise and predictable elastic force. By winding the compression spring 7 around the mandrel 4, the radial space inside the sleeve 110 is fully utilized, achieving a compact structure. Simultaneously, the mandrel 4 effectively guides the compression spring 7, preventing buckling or deflection during compression and ensuring that the spring always deforms smoothly along the axial direction. This not only extends the spring's service life but also guarantees the accuracy of the output force direction. When the first coupling 2 is subjected to force, driving the mandrel 4 to move, the compression spring 7 is stably compressed, generating a continuous and constant-direction thrust. This thrust is cleverly converted into a pulling force on the two driven arms 9 through the mechanism. This force conversion mechanism is more reliable than directly using a tension spring because the compression spring 7 is less susceptible to external interference when working in a closed environment. Furthermore, a single compression spring 7 can replace the traditional double tension spring structure, simplifying the structural composition, reducing the number of parts and manufacturing costs, while improving the system's reliability.

[0041] In one embodiment, the receiving cavity 120 includes a sealing cavity 130 communicating with the second connection port 112, and the second positioning member 6 extends from the second connection port 112 into the sealing cavity 130.

[0042] As an important component of the receiving cavity 120, the sealing cavity 130 is specifically designed to accommodate and fix the second positioning member 6. This specialized cavity structure provides precise positioning and sufficient support contact surface for the second positioning member 6, ensuring its stability under axial force. The installation method of the second positioning member 6 extending into the sealing cavity 130 from the second connection port 112 forms an embedded connection mechanism, which facilitates the uniform transmission and dispersion of force and avoids stress concentration. Simultaneously, the sealing cavity 130 makes sealing at the second connection port 112 easier to achieve, allowing it to form an effective sealing barrier with components such as sealing rings, further enhancing the overall airtightness of the receiving cavity 120 and providing a cleaner working environment for internal precision components such as the compression spring 7 and the spindle 4. Furthermore, it facilitates the rapid installation and fixation of the second positioning member 6; whether using interference fit, bonding, or retaining ring fixation as described in subsequent claims, the sealing cavity 130 provides the assembly basis.

[0043] Preferably, the sealing cavity 130 further includes a wire retaining ring 8 disposed between the second positioning member 6 and the inner wall of the sleeve 110, and the wire retaining ring 8 is disposed circumferentially along the second positioning member 6.

[0044] The wire retaining ring 8 is a standard elastic fastener specifically designed for axial positioning of parts within holes. Its unique circular cross-section and uniform elastic distribution give it superior performance in withstanding vibration and impact loads. Compared to traditional threaded connections, this threadless connection method fundamentally eliminates the risk of loosening or stripping due to vibration, making it suitable for applications like the Delta parallel robot, which operates under high-frequency, high-acceleration motion for extended periods. The wire retaining ring 8 is easy and quick to install; simply placing it into the pre-set retaining ring groove achieves reliable fixation. Disassembly is also accomplished with just special clamps, greatly improving assembly and maintenance efficiency. Furthermore, the contact surfaces formed between the wire retaining ring 8 and the inner walls of the plug 610 and sleeve 110 are uniform, with a reasonable stress distribution, preventing wear or deformation caused by excessive local stress and extending the service life of the connection point. This method, in conjunction with the elastic retaining ring 510 at the first end, forms a unified technical approach where both ends of the connection mechanism employ a threadless anti-loosening design, ensuring the connection integrity and functional stability of the entire mechanism during long-term operation.

[0045] Preferably, both the first attachment part 2 and the second attachment part 3 are provided with two hooks 210, and the two hooks 210 located on the same side form a clamping area for accommodating the driven arm 9.

[0046] Understandably, the driven boom 9 is provided with a suitable attachment point for connecting the aforementioned hooks 210. The hook-type attachment part borrows from the working principle of a lifting hook, making the installation process of the driven boom 9 as simple and intuitive as "hanging clothes," achieving true tool-free operation. This has great practical value in industrial sites where maintenance efficiency is extremely important. The clamping area formed by the two hooks 210 on the same side provides a space for accommodating and locking the connection end of the driven boom 9. This double-point contact clamping method not only ensures the spatial stability of the connection, preventing the driven boom 9 from swinging or rotating at the connection point, but also allows the hooks 210 to produce a self-centering and self-locking effect when subjected to tension, becoming tighter the more it is pulled. This ensures the directness and efficiency of force transmission, has good tolerance, and can accommodate dimensional deviations within a certain range at the connection end of the driven boom 9, reducing the precision requirements for machining and assembly. Meanwhile, this structural design also makes the disassembly of the driven arm 9 convenient, requiring only simple axial movement to separate it. This greatly facilitates the robot's rapid reconfiguration, component replacement, or routine maintenance, significantly reducing downtime and improving the overall operational efficiency.

[0047] A parallel robot includes driven arms 9, with a connection mechanism as described in any of the foregoing embodiments provided between two adjacent driven arms 9.

[0048] For any parts not mentioned in this application, existing technologies may be used or referenced.

[0049] The various embodiments in this specification are described in a progressive manner. The same or similar parts between the various embodiments can be referred to each other. Each embodiment focuses on describing the differences from other embodiments.

[0050] The above description is merely an embodiment of this application and is not intended to limit the scope of this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of the claims of this application.

Claims

1. A parallel robot slave arm connection mechanism, characterized in that, The connection mechanism includes a connecting body and a first hook-on portion and a second hook-on portion located at both ends of the connecting body. The first hook-on portion and the second hook-on portion are respectively connected to two adjacent driven arms. The connecting body has a receiving cavity inside, and a mandrel is provided in the receiving cavity along the axial direction of the connecting body. The mandrel extends at least partially out of the receiving cavity to connect to the first hook-on portion. The connection mechanism also includes a first positioning member and a second positioning member respectively disposed at both ends of the connecting body. The first hook-on portion has a first positioning hole through which the mandrel passes, and the mandrel passes through the first positioning hole to connect with the first positioning member. The second hook-on portion has a second positioning hole, and the second positioning member passes through the second positioning hole and is fixed to the connecting body.

2. The parallel robot driven arm connection mechanism according to claim 1, characterized in that, The connecting body includes a sleeve, the sleeve is hollow to form the receiving cavity, and the two ends of the sleeve are provided with a first connection port and a second connection port respectively. The mandrel passes through the first connection port and the second positioning member passes through the second connection port.

3. The parallel robot driven arm connection mechanism according to claim 2, characterized in that, The first positioning element includes an elastic retaining ring; and / or, the second positioning element includes a plug.

4. The parallel robot driven arm connection mechanism according to claim 2, characterized in that, The connecting mechanism further includes an elastic element disposed within the receiving cavity, and an abutment portion is provided at the end of the spindle away from the first hook portion, and the elastic element abuts against the abutment portion.

5. The parallel robot driven arm connection mechanism according to claim 4, characterized in that, The elastic element includes a compression spring, which is wound around the outside of the spindle. When the first hook is subjected to force, the spindle moves toward the first connection port to compress the compression spring.

6. The parallel robot driven arm connection mechanism according to claim 2, characterized in that, The receiving cavity includes a sealing cavity communicating with the second connection port, and the second positioning member extends into the sealing cavity from the second connection port.

7. The parallel robot driven arm connection mechanism according to claim 6, characterized in that, The sealing cavity also includes a wire retaining ring disposed between the second positioning member and the inner wall of the sleeve, the wire retaining ring being disposed circumferentially along the second positioning member.

8. The parallel robot driven arm connection mechanism according to claim 1, characterized in that, Both the first and second attachment parts are provided with two hooks, and a clamping area for accommodating the driven arm is formed between the two hooks on the same side.

9. A parallel robot, characterized in that, It includes a driven arm, and a connecting mechanism as described in any one of claims 1-8 is provided between two adjacent driven arms.

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