A stiffness improvement mechanism and working method for a robot

Abstract

The present invention discloses a stiffness improvement mechanism and a working method for a robot, which relates to the technical field of robots, solves the problem of chatter in the structure of existing industrial robots, and has the beneficial effect of suppressing the chatter of the robot structure. The specific solution is as follows: A stiffness improvement mechanism for a robot includes a base bracket provided at the first joint of the robot. The base bracket supports a damper member. A two-axis joint damping disc is provided at the second joint of the robot. A pulley group is provided at the two-axis joint damping disc. A boom bracket is provided at the second link boom of the robot. A sub-arm bracket is provided at the parallel link sub-arm of the robot. A damping cable connects the boom bracket and the sub-arm bracket and then winds around to the damper member, and then continues to pass through a tensioning device and bypasses the pulley group at the two-axis joint damping disc. The torque direction of the damping cable is changed by the pulley group, and the damping cable provides a damping torque to the robot.

Description

Technical Field

[0001] The present invention relates to the technical field of robots, and in particular to a stiffness improvement mechanism and working method for robots. Background Technique

[0002] The statements in this part only provide background technical information related to the present invention and do not necessarily constitute prior art.

[0003] Industrial robots are widely used in multiple fields due to their large reachable space, high dexterity, compact volume, and versatility, promoting the transformation of traditional industries from traditional labor-intensive to technology-intensive, and improving the overall level and competitiveness of high-end manufacturing. However, industrial robots are typical open-chain multi-link serial structures. Affected by the coupling of factors such as transmission mechanisms, joint deformations, friction, and the environment, they are prone to induce robot resonance and generate medium and low-frequency chatter when processing high-strength workpieces. Moreover, the stiffness of the robot has the characteristic of non-linear distribution in the entire working space. The external forces received by the robot during the processing process will cause irregular deviations, thereby affecting the surface quality and machining accuracy of the workpiece. Research shows that the robot positioning errors caused by geometric factors and stiffness factors of the robot account for more than 90% of all positioning errors, severely restricting the application of industrial robots in high-precision machining processes.

[0004] The currently commonly used method is to perform offline optimization of process parameters for machining chatter. The working condition versatility is poor, and the suppression method is limited by the weak stiffness characteristics of the robot itself. It cannot accurately compensate for the elastic deformation motion of the joints while the robotic arm rotates rigidly, and there are still problems such as multi-variable input, strong non-linearity, and severe coupling of dynamic characteristics.

[0005] The chatter of the robot structure mainly comes from the radial and axial clearances that cannot be adjusted during the joint driving process, showing joint flexibility and weak stiffness of the end machining trajectory. For the existing methods for suppressing chatter of industrial robots, mainly by attaching a chatter suppression device to the end effector, semi-active and passive vibration suppression methods are used to introduce the machining vibration energy into the additional device to achieve dissipation, thereby improving the dynamic stiffness of the robot machining trajectory. However, the machining stiffness of the robot is highly related to the pose. During the part machining process, the end dynamic stiffness has the characteristic of spatial time-variation, and the end vibration suppression device will introduce additional rotational inertia, affecting the environmental adaptability and dynamic response of the robot, causing redundant waste of the joint output torque, and having certain application limitations. Summary of the Invention

[0006] Aiming at the deficiencies of the existing technology, the purpose of the present invention is to provide a stiffness improvement mechanism for robots, which realizes the dissipation of chatter energy during the robot machining process through a damper component and optimizes the system structure stiffness.

[0007] To achieve the above object, the present invention is realized by the following technical solutions:

[0008] A stiffness improvement mechanism for a robot, comprising a base bracket provided at the first joint of the robot, the base bracket supporting a damper member, a two-axis joint damper disc provided at the second joint of the robot, a pulley group provided at the two-axis joint damper disc, a boom bracket provided at the second link boom of the robot, and a sub-arm bracket provided at the parallel link sub-arm of the robot. A damping cable connects the boom bracket and the sub-arm bracket and then winds around to the damper member, and then passes through a tensioning device and bypasses the pulley group at the two-axis joint damper disc. The direction of the moment of the damping cable is changed by the pulley group, and the damping cable provides a damping moment to the robot.

[0009] A stiffness improvement mechanism for a robot as described above further comprises a first pulley and a second pulley. The first pulley is disposed at the hinge joint of the parallel link sub-arm and the second link boom, and the second pulley is disposed below the two-axis joint damper disc. The damping cable is arranged to bypass the first pulley and the second pulley to change the direction of the damping cable through the first pulley and the second pulley.

[0010] A stiffness improvement mechanism for a robot as described above, the damping cable comprises two segments. The first segment of the damping cable passes through the boom bracket, the sub-arm bracket and the first pulley in sequence. The second segment of the damping cable passes through the pulley group, the second pulley, the tensioning device and the damper member in sequence. The first segment of the damping cable is connected to the second segment of the damper cable through a tension sensor to form a closed cable assembly.

[0011] A stiffness improvement mechanism for a robot as described above, the two-axis joint damper disc comprises a pulley group base, the pulley group base is coaxially connected to the second joint, the pulley group base supports the pulley group, the pulley group comprises a third pulley and a fourth pulley, there are multiple third pulleys, and there are at least two fourth pulleys. The multiple third pulleys are arranged along the circumferential direction of the pulley group base, the fourth pulley is located inside the third pulley, one side of the pulley group base protrudes, a redirecting pulley is provided at the protruding part of the pulley group base, and the damping cable passes through some of the third pulleys, the fourth pulley, the other third pulleys and the redirecting pulley in sequence, so that the section of the damping cable between the redirecting pulley and the boom bracket has the same direction as the second link boom.

[0012] A stiffness improvement mechanism for a robot as described above, a stop member is further provided at the protruding part of the pulley group base, the stop member connects the pulley shaft of the redirecting pulley and the protruding part of the pulley group base, and a distance is set between the stop member and the redirecting pulley to limit the damping cable.

[0013] A stiffness improvement mechanism for a robot as described above, wherein there are at least two boom brackets, the boom brackets are fixed to the circumferential direction of the second link boom, the eyebolt is installed on the side of the boom bracket, the damping cable passes through the eyebolt of the boom bracket, and the eyebolt is installed on the boom bracket through a boom eyebolt fixing part;

[0014] There is at least one auxiliary boom bracket, the auxiliary boom bracket is arranged staggeredly with the boom bracket, the auxiliary boom bracket is fixed to the circumferential direction of the parallel link auxiliary boom, the eyebolt is installed on the side of the auxiliary boom bracket, the damping cable passes through the eyebolt at the auxiliary boom bracket, and the eyebolt is installed on the auxiliary boom bracket through an auxiliary boom eyebolt fixing part;

[0015] The structures of the boom eyebolt fixing part and the auxiliary boom eyebolt fixing part are the same. Both of them include a convex cavity, a second nut is arranged in the convex cavity, a third nut is arranged outside the convex cavity, and the eyebolt passes through the third nut and the second nut in sequence.

[0016] A stiffness improvement mechanism for a robot as described above, wherein an adaptive tightening claw is arranged on the side of the boom bracket. The adaptive tightening claw includes an adjusting bolt, the adjusting bolt passes through a welding nut and the side of the boom bracket, the welding nut is fixed to the side of the boom bracket, the end of the adjusting bolt is connected to a fastening hinge point, the fastening hinge point is hinged to a claw lobe, and the claw lobe can rotate along the fastening hinge point to adapt to the second link boom.

[0017] A stiffness improvement mechanism for a robot as described above, wherein the damper member includes two sliding damper assemblies, a tension pulley is arranged between the two sliding damper assemblies, the damping cable bypasses the tension pulley, the sliding damper assembly includes two dampers arranged oppositely, the telescopic ends of the two dampers are both connected to a damper center block, a damper center rod passes through the damper center block, one end of the damper center rod passing through the damper center block is connected to the base bracket, the other end of the damper center rod passes through a damper limit block, tension springs are sleeved on both sides of the damper center rod located at the damper center block, and the fixed ends of the dampers are connected to the base bracket and the damper limit block respectively through connecting rods.

[0018] A stiffness improvement mechanism for a robot as described above, wherein the tensioning device includes a tensioning bracket, the tensioning bracket is installed on the base bracket, the position of the tensioning bracket relative to the base bracket is adjustable, the tensioning bracket supports a tensioning adjustment assembly and a tensioning clamping assembly, the tensioning adjustment assembly includes a moving part, the moving part is slidably installed on the tensioning bracket, the moving part is connected to a cylindrical clamping shaft, a fifth pulley is arranged at one end of the cylindrical clamping shaft far away from the moving part, the damping cable bypasses the fifth pulley to adjust the tensioning degree of the damping cable through the moving part, and a stop part is arranged on one side of the fifth pulley.

[0019] As described above, a stiffness enhancement mechanism for a robot, the tensioning clamping assembly clamps the cylindrical clamping shaft and is capable of locking the cylindrical clamping shaft, the fifth pulley is arranged below the damper component, and the cylindrical clamping shaft is arranged inclined upward relative to the bottom of the base bracket.

[0020] As described above, a stiffness enhancement mechanism for a robot, the base bracket includes a bottom frame, the bottom frame supports a vertical frame, the vertical frame supports a mounting plate, the mounting plate is provided with multiple layers of mounting holes, the mounting holes of two adjacent layers of mounting holes are staggered, and the damper component is installed on the mounting plate through the mounting holes.

[0021] In a second aspect, the present invention further provides a working method for a stiffness enhancement mechanism of a robot, comprising the following contents:

[0022] A base bracket is arranged at the first joint of the robot, the base bracket supports the damper component, a two-axis joint damping disk is arranged at the second joint, a pulley block is arranged at the two-axis joint damping disk, a big arm bracket is arranged at the second connecting rod big arm, and a jib bracket is arranged at the parallel connecting rod jib;

[0023] The damping cable is connected to the boom support and the auxiliary arm support and then goes around the damper component, and then passes through the tensioning device and around the pulley block at the two-axis joint damping plate;

[0024] The robot is in a zero-position posture, the damper component provides a damping internal force for the damping cable, and the tensioning device abuts against the damping cable and deforms it to provide an initial tensioning force according to actual application requirements;

[0025] During the working process of the first arm, the second link arm, the parallel link jib and the third arm of the robot, a damping torque is introduced to the second joint, the second link arm and the parallel link jib through the damping cable to realize the dissipation of the flutter energy of the joint structure.

[0026] The beneficial effects of the present invention are as follows:

[0027] 1) In order to solve the problems of weak structural rigidity and severe dynamic coupling of industrial robots, the present invention connects the second link arm and the parallel link auxiliary arm through damping cables, and provides damping through a damper component. In this way, the damping torque is introduced to the second joint, the third joint, the second link arm and the parallel link auxiliary arm of the robot through the damping cables, so as to achieve effective dissipation of the flutter energy of the joint structure and improve the processing stability and precision of the robot. At the same time, the stiffness improvement mechanism is designed to fit the structure of the industrial robot without interfering with its original degrees of freedom and workspace, ensuring that the robot meets the requirements of complex working tasks and has high adaptability and compatibility. In this way, the processing precision of the industrial robot is improved without sacrificing the environmental adaptability and dynamic response characteristics of the robot.

[0028] 2) The present invention can adjust the tension on the damping cable to an appropriate range according to the inherent mode of the robot joint, ensure the modal matching state between the robot and the stiffness improvement mechanism, thereby inducing the vibration generated by the joint during the robot processing to the damping cable, thereby reducing the modal frequency of the robot joint. At the same time, the sliding damping component can automatically adjust the motion range of the damping cable according to the motion state of the robot arm during the processing, and effectively apply a stable damping force to the damping cable, so that the robot with the stiffness improvement mechanism can maintain the continuity and stability of the damping internal force under various processing conditions.

[0029] 3) The pulley block structure of the present invention is reasonably arranged. The pulley block includes a third pulley and a fourth pulley. The third pulley is located outside the fourth pulley. In this way, the damping cable can pass around part of the third pulley and the fourth pulley and then pass around another third pulley. The damping cable can be redirected by setting a redirection pulley.

[0030] 4) The structures of the boom support and the jib support in the present invention are reasonably arranged, and cooperate with the second connecting rod boom and the parallel connecting rod jib of the robot respectively to ensure stable arrangement. An adaptive clamping claw is arranged at the boom support to effectively fit with the second connecting rod boom. The boom support and the jib support respectively support the corresponding eye bolts through the boom lifting ring fixing parts and the jib lifting ring fixing parts to ensure the stable arrangement of the eye bolts and prevent the eye bolts from moving due to the traction force of the damping cable. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The accompanying drawings in the specification, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0032] Figure 1 An assembly diagram of a robot with a stiffness enhancement mechanism according to one or more embodiments of the present invention.

[0033] Figure 2 An exploded view of a two-axis joint damping disk of a robot with a stiffness enhancement mechanism according to one or more embodiments of the present invention.

[0034] Figure 3 The present invention is a schematic diagram of the passage of the damping cable in a robot pulley block with a stiffness enhancement mechanism according to one or more embodiments of the present invention.

[0035] Figure 4 An exploded view of a robot arm support with a stiffness enhancement mechanism according to one or more embodiments of the present invention.

[0036] Figure 5 An exploded view of a robot auxiliary arm bracket with a stiffness enhancement mechanism according to one or more embodiments of the present invention.

[0037] Figure 6 Explosion diagram of the robot base bracket with a stiffness improvement mechanism for one or more embodiments of the present invention.

[0038] Figure 7 Explosion diagram of the robot tensioning device with a stiffness improvement mechanism for one or more embodiments of the present invention.

[0039] Figure 8 Explosion diagram of the robot tensioning motion device with a stiffness improvement mechanism for one or more embodiments of the present invention.

[0040] Figure 9 Explosion diagram of the overall assembly of the robot damper with a stiffness improvement mechanism for one or more embodiments of the present invention.

[0041] Figure 10 Explosion diagram of the robot sliding damper device with a stiffness improvement mechanism for one or more embodiments of the present invention.

[0042] Figure 11 Explosion diagram of the overall assembly of the robot closed cable with a stiffness improvement mechanism for one or more embodiments of the present invention.

[0043] Figure 12 Assembly drawing of the robot with a stiffness improvement mechanism for one or more embodiments of the present invention when the robot is in the zero posture.

[0044] Figure 13 Assembly drawing of the robot with a stiffness improvement mechanism for one or more embodiments of the present invention when the robot is in the limit position.

[0045] In the figure: The distances or dimensions between each part are exaggerated for showing the positions of each part, and the schematic diagram is only for illustration.

[0046] Among them: 1. Two-axis joint damping disc; 2. Boom bracket; 3. Sub-boom bracket; 4. Base bracket; 5. Tensioning device; 6. Damper component; 7. Closed cable assembly; 8. First steering pulley bracket; 9. Second steering pulley bracket; 10. Fixed bracket; 11. Base; 12. First arm; 13. Second joint; 14. Second link boom; 15. Parallel link sub-boom; 16. Third joint; 17. Fourth link; 18. End effector;

[0047] 101. Adapter plate; 102. Pulley group base; 103. Pulley group; 104. Pulley group top cover; 105. Redirecting pulley; 106. Retaining plate; 107. Pin; 108. Snap ring; 109. Split pin; 110. Pulley fastening nut; 111. Third pulley; 112. Fourth pulley;

[0048] 201. Boom support bottom plate; 202. U-shaped plate of boom support; 203. First bolt; 204. First nut; 205. Rubber anti-slip pad for boom; 206. Adjusting bolt; 207. Welding nut; 208. Fastening hinge point; 209. Clamping claw lobe; 210. Fixing part for boom lifting ring; 211. Second bolt; 212. Second nut; 213. Third nut; 214. Lifting ring bolt;

[0049] 301. U-shaped plate of auxiliary boom support; 302. Rubber anti-slip pad for auxiliary boom; 303. Fixing part for auxiliary boom lifting ring;

[0050] 401. First support frame; 402. Second support frame; 403. Third support frame; 404. Third bolt; 405. Boat-shaped nut; 406. Right-angle angle bracket; 407. Acute-angle angle bracket; 408. Obtuse-angle angle bracket; 409. Mounting plate;

[0051] 501. Fourth support frame; 502. Fifth support frame; 503. Clamping plate; 504. Deep groove ball bearing; 505. Gear shaft; 506. Runner; 507. Rack; 508. Fourth bolt; 509. Cylindrical clamping shaft; 510. First clamping block; 511. Second clamping block; 512. Locking bolt;

[0052] 601. Tension pulley; 602. Viscous damper; 603. Center block of damper; 604. Pin shaft; 605. Center rod of damper; 606. Tension spring; 607. Damper base; 608. Damper limit block; 609. Connecting rod; 610. Connecting pad;

[0053] 701. First tension sensor; 702. Second tension sensor; 703. Damping cable; 7031. First section of damping cable; 7032. Second section of damping cable;

[0054] 801. First pulley; 901. Second pulley. Detailed implementation manners

[0055] It should be noted that the following detailed description is illustrative and is intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used in the present invention have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present invention belongs.

[0056] It should be noted that the terms used herein are only for describing specific implementation manners and are not intended to limit the exemplary embodiments according to the present invention. As used herein, unless the present invention clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should also be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof;

[0057] As introduced in the background art, there is a problem of low-frequency flutter during the movement of robots in the prior art. To solve the above technical problems, the present invention proposes a stiffness improvement mechanism for robots.

[0058] Embodiment 1

[0059] In a typical implementation manner of the present invention, with reference to Figure 1 As shown, a stiffness improvement mechanism for a robot. The robot includes a base 11. The base 11 rotatably supports a first arm 12 through a first joint. The first arm 12 is connected to a second link large arm 14 through a second joint 13. A parallel link sub-arm 15 is arranged on the side of the second link large arm 14. The second link large arm 14 and the parallel link sub-arm 15 are connected to a third arm through a third joint 16. The third arm is connected to a fourth link 17. An end effector 18 is arranged at the end of the robot. The stiffness improvement mechanism includes a base bracket 4 arranged at the first joint of the robot. The base bracket 4 supports a damper member 6. A two-axis joint damper disc 1 is arranged at the second joint 13 of the robot. A pulley group 103 is arranged at the two-axis joint damper disc 1. A large arm bracket 2 is arranged at the second link large arm 14 of the robot. A sub-arm bracket 3 is arranged at the parallel link sub-arm 15 (the parallel link sub-arm 15 is located on one side of the second link large arm 14) of the robot. A damping cable 703 connects the large arm bracket 2 and the sub-arm bracket 3 and then winds around to the damper member 6, and continues to pass through a tensioning device 5 and bypasses the pulley group at the two-axis joint damper disc 1. The torque direction of the damping cable is changed through the pulley group, and the damping cable 703 provides a damping torque to the robot.

[0060] In this embodiment, the two-axis joint damper disc 1 is fixed to a preset threaded hole at the second joint 13 of the robot by bolts and coincides with the central axis of the second joint 13. A plurality of large arm brackets 2 are evenly arranged on the second link large arm 14 of the robot as required. The number of large arm brackets 2 is greater than or equal to two. At least one sub-arm bracket 3 is evenly arranged at the parallel link sub-arm 15 of the robot as required. The large arm brackets 2 and the sub-arm brackets 3 are arranged in a staggered manner, that is, the first sub-arm bracket 3 is arranged higher than the first large arm bracket 2. The number of large arm brackets 2 is one more than the number of sub-arm brackets 3. The damping cable 703 sequentially bypasses the pulley group 103, a redirecting pulley 105, the large arm brackets 2, and the sub-arm brackets 3 in the two-axis joint damper disc 1 and forms a closed loop, thus forming a closed cable assembly 7;

[0061] In addition, a tensioning device 5 is used to change the extension length of the damping cable 703, thereby adjusting the initial pre-tightening force of the closed cable assembly 7; a damper member 6 is used to compensate for the dynamic change in the position of the damping cable 703 during the movement of the robot, preventing the cable from breaking due to excessive extension. At the same time, during the change in the extension length of the damper member 6, a continuous and stable damping internal force can be provided for the closed cable assembly 7.

[0062] It should be noted that considering that there is likely to be interference between the damping cable 703 and the robot structural members when the damping cable 703 passes through the two-axis joint damping disc 1 and the boom bracket 2, in order to adjust the passing path of the damping cable 703, a first steering pulley bracket 8 is provided at the upper hinge point position of the parallel link secondary arm 15 of the robot. A first pulley 801 is provided at the first steering pulley bracket 8. A second steering pulley bracket 9 is provided below the second joint 13 of the robot. A second pulley 901 is provided at the second steering pulley bracket 9. Both sides of the second pulley 901 are fixed to the second steering pulley bracket 9 through pulley fastening nuts.

[0063] Reference Figure 2 、 Figure 3 and Figure 12 As shown in

[0064] Specifically, the third pulley mounting holes are evenly opened along the circumferential direction of the pulley group base 102. There are eight third pulley mounting holes. All eight axially distributed pulley mounting holes need to install the third pulley 111. The fourth pulley mounting holes are opened near the axis of the pulley group base 102. The number of the fourth pulley mounting holes is four. The centers of these four pulley mounting holes are distributed in a rectangle. Only two of the four pulley mounting holes distributed in a rectangle need to be installed diagonally with the fourth pulley 112 as required. In this way, ten pulleys are provided at the pulley group base 102 to form the pulley group 103. After the damping cable 703 bypasses some of the circumferential third pulleys (such as four third pulleys), then bypasses two fourth pulleys 112, and then continues to bypass the remaining third pulleys 111. In this way, after the damping cable 703 passes through the pulley group 103 provided in a series of pulley mounting holes, the internal force in the damping cable 703 can be converted into a joint damping torque, thereby suppressing the torque fluctuation caused by the joint non-linear friction and clearance.

[0065] Among them, the damping cable 703 bypasses the first fourth pulley 112 and then reversely bypasses the second fourth pulley 112.

[0066] In this embodiment, the pulley group top cover 104 is provided with fixing holes according to the positions of the third pulley mounting holes and the fourth pulley mounting holes on the pulley group base 102, and is fixed to the unfixed end of the pulley group 103 through pulley fastening nuts 110. After the adapter plate 101, the pulley group base 102, and the pulley group top cover 104 are installed, the central axes of the three are completely coincident.

[0067] It is easily understandable that in the series direction of the damping cable 703 from the two-axis joint damping disc 1 to the large arm bracket 2, a fifth pulley mounting hole is provided on the outer extension platform of the pulley group base 102, and a redirecting pulley 105 is installed through the third pulley mounting hole. A stop member is provided at the redirecting pulley 105. The stop member includes retaining plates 106 provided at both ends of the redirecting pulley shaft. A retaining ring 108 is connected in series through a pin 107 in the outer holes of the retaining plates 106 to prevent the damping cable 703 from slipping out of the groove, and the pin 107 is fixed by a split pin 109.

[0068] To ensure the versatility of the robot and without performing destructive modification on the robot, three groups of large arm brackets 2 are provided on the second link large arm 14 of the robot to provide damping force application points, and the distance between adjacent large arm brackets 2 is set at intervals. Refer to Figure 4 and Figure 12 As shown, the large arm bracket 2 includes a large arm bracket bottom plate 201 and a large arm bracket U-shaped plate 202. After the two are fitted and installed, the rectangular cross-section of the middle cavity is slightly larger than the cross-section of the second link large arm 14 of the robot. Three bolt through holes are provided at the fitting part of the two, and the second link large arm 14 of the robot is locked through the first bolt 203 and the first nut 204. A large arm rubber anti-slip pad 205 is adhesively provided on the side of the mechanical arm where the large arm bracket bottom plate 201 and the large arm bracket U-shaped plate 202 are fitted. The large arm rubber anti-slip pad 205 can prevent wear or scratches caused by hard contact between the large arm bracket 2 and the second link large arm of the robot. At the same time, the elastic deformation of the large arm rubber anti-slip pad 205 can increase the friction force and prevent the large arm bracket 2 from sliding with the second link large arm 14 of the robot after being subjected to the tension of the damping cable 703. The thickness and shape of the large arm rubber anti-slip pad 205 are selected according to the installation effect and are not specifically limited here.

[0069] Since the side of the second link of the robot, the large arm 14, is arc-shaped and the cross-sectional shape is not fixed, to ensure the complete fixation of the large arm bracket 2 to the robot, three groups of adaptive clamping claws are provided on the side of the large arm bracket 2 close to the end effector of the robot to prevent the large arm bracket 2 from sliding along the axis direction of the fourth link 17 of the robot. Three positioning and mounting holes are provided on the side of the U-shaped plate 202 of the large arm bracket on the corresponding side for mounting the adaptive clamping claws. The adaptive clamping claws include an adjusting bolt 206, a welding nut 207, a fastening hinge point 208, and a clamping claw lobe 209. The welding nut 207 is fixed to the positioning and mounting hole of the U-shaped plate 202 of the large arm bracket by welding. The adjusting bolt 206 passes through the welding nut 207 and is threadedly connected to the fastening hinge point 208 at the end. The fastening hinge point 208 and the clamping claw lobe 209 are fixed by a hinged manner. The hinge hole is installed by a split pin 109. The anti-slip rubber pad is adhesively provided on the side of the clamping claw lobe 209 close to the side of the robotic arm to increase the fastening force. The tightness between the clamping claw lobe 209 and the side of the robotic arm is adjusted by tightening the adjusting bolt 206. At the same time, the clamping claw lobe 209 rotates along the fastening hinge point 208 to adapt to the arc of the side of the robotic arm.

[0070] Specifically, referring to Figure 4 As shown, a large arm sling fixing member 210 is provided on the side of the large arm bracket 2 away from the end effector of the robot. Five threaded holes are evenly provided on the side of the U-shaped plate 202 of the large arm bracket on the corresponding side. The large arm sling fixing member 210 is internally provided with a convex cavity. Five bolt counterbores are correspondingly provided inside the convex cavity. It is fixed to the U-shaped plate 202 of the large arm bracket by a second bolt 211. A second nut 212 is provided inside the convex cavity, and a third nut 213 is provided outside the convex cavity. The thread directions of the second nut 212 and the third nut 213 are opposite. The sling bolt 214 sequentially passes through the third nut 213 and the convex cavity and is screwed into the second nut 212. Among them, the sling bolt 214 can adjust the fixing position along the cavity of the large arm sling fixing member 210 according to the threading mode of the damping cable 703. Tightening the sling bolt 214 can clamp the second nut 212 and the third nut 213 to the large arm sling fixing member 210, thereby preventing the movement of the sling bolt 214 caused by the traction force of the damping cable 703.

[0071] Referring to Figure 5 and Figure 12As shown in the figure, two sets of sub-arm brackets 3 are provided on the parallel link sub-arm of the robot. The sub-arm brackets 3 provide a damping force application point for the damping cable 703. The sub-arm bracket 3 includes two oppositely arranged U-shaped plates 301 of the sub-arm bracket. After they are fitted and installed, the rectangular cross-section of the middle cavity is slightly larger than the cross-section of the parallel link sub-arm of the robot. A bolt through-hole is opened at each of the fitting parts. The parallel link sub-arm 15 of the robot is locked by another first bolt 203 and a first nut 204. The U-shaped plate 301 of the sub-arm bracket is adhesively provided with a sub-arm rubber anti-slip pad 302 on the side of the parallel sub-arm. The function of the sub-arm rubber anti-slip pad 302 is the same as that of the main-arm rubber anti-slip pad 205. The thickness and shape of the rubber anti-slip pad are selected according to the installation effect and are not specifically limited here.

[0072] It is easily understood that a sub-arm sling fixing member 303 is provided on the side of the sub-arm bracket 3 close to the main arm of the second link of the robot. Two threaded holes are evenly opened on the side surface of the corresponding U-shaped plate 301 of the sub-arm bracket. The sub-arm sling fixing member 303 also has a convex cavity inside. Two bolt counterbores are correspondingly provided inside the second convex cavity. The second bolt 211 is fixed on the U-shaped plate 301 of the sub-arm bracket. The second nut 212 is arranged inside the convex cavity, and the third nut 213 is arranged outside the convex cavity. The installation method of the sub-arm sling fixing member 303 on the sub-arm bracket 3 is the same as the installation method of the main-arm sling fixing member 210 in the main-arm bracket 2.

[0073] Reference Figure 6 and Figure 12 As shown in the figure, in order to reduce the influence of the stiffness improvement mechanism on the working range of the industrial robot, four fixing brackets 10 are installed at multiple threaded mounting holes reserved at the first joint of the robot. The base bracket 4 is fixed to the first joint of the robot through the fixing bracket 10. The base bracket 4 is connected to the fixing bracket 10 through a third bolt 404 and a boat-shaped nut 405, so that the stiffness improvement mechanism can rotate with the first-axis joint of the robot without interference. The fixing bracket can specifically be a support block.

[0074] In this embodiment, the main body of the base bracket 4 is composed of four first support frames 401 with a length of 900 mm, two second support frames 402 with a length of 1060 mm and 45° bevel cuts at both ends, and two third support frames 403 with a length of 611 mm. The cross-sectional dimension parameters of the support frames are selected according to the actual installation requirements and are not specifically limited here.

[0075] Among them, four first support frames 401 and two second support frames 402 form two sets of right-angled triangular frames. A third support frame 403 is set at the right-angled points of the two sets of triangular frames for connection. Another third support frame 403 is used as a reinforcement beam and is arranged between the two first support frames 401 connected to the fixed bracket according to the actual installation conditions. Each aluminum profile is connected by a right-angle corner code 406 or an acute-angle corner code 407 or an obtuse-angle corner code 408 according to the included angle space. The first support frame 401 is provided with a mounting plate 409 along the direction perpendicular to the bottom surface of the robot base. The mounting plate 409 is provided with 15 rows of transverse mounting holes parallel to the third support frame 403. The transverse mounting holes between different rows are staggered, and the fixing holes can be selected according to needs to facilitate the adjustment of the position of the damper member 6. Each support frame, corner code, and mounting plate 409 in the base bracket 4 are fixed by a boat-shaped nut 405 and a third bolt 404.

[0076] It should be explained that the tensioning device 5 includes a tensioning bracket, a tensioning adjustment component, and a tensioning clamping component. Refer to Figure 7 As shown, the tensioning bracket is composed of two fourth support frames 501 with a length of 300 mm and 45° beveled ends at both ends and a fifth support frame 502 with a length of 500 mm and a 45° beveled end at one end. Among them, the two fourth support frames 501 are vertically placed, and the fifth support frame 502 is added as the hypotenuse to form a right-angled triangular frame, which is connected by corner codes with different included angles, a third bolt 404, and a boat-shaped nut 405. The tensioning bracket is vertically arranged between the two third support frames 403 of the base bracket 4 and is connected by a corner code, a third bolt 404, and a boat-shaped nut 405. The right-angled point of the tensioning bracket is set on the third support frame 403 close to the end effector side of the robot. By removing the bolts, the tensioning bracket can be horizontally moved along the third support frame 403 to facilitate the adjustment of the position of the tensioning device 5.

[0077] Refer to Figure 8As shown in the figure, the tension adjustment assembly includes two clamping plates 503 symmetrically fixed to the fifth support frame 502 by the third bolt 404 and the boat-shaped nut 405. A bearing seat hole is provided on the clamping plate 503, and a deep groove ball bearing 504 is arranged in the bearing seat hole. The gear shaft 505 arranged between the two clamping plates 503 passes through the deep groove ball bearing 504 for connection, and one end thereof passes out of the clamping plate 503 and is fixedly connected to the runner 506 by a thread. A rack 507 is slidably arranged on the upper side of the fifth support frame 502. The rack 507 meshes with the gear shaft 505. Four threaded holes are provided on the side of the rack 507 close to the end effector of the robot, and the cylindrical clamping shaft 509 is fixedly connected by the fourth bolt 508. A pulley groove is provided at the end of the cylindrical clamping shaft 509. The fifth pulley is fixed between the pulley grooves by a pulley fastening nut. Similar to the deflecting pulley 105 arranged on the outer extension platform of the two-axis joint damping disc 1, retaining plates 106 and retaining rings 108 are arranged at both ends of the pulley, and the pin 107 passes through the retaining ring. The damping cable passes around the pulley and then passes through the retaining ring to prevent the damping cable 703 from slipping out of the groove.

[0078] It is easily understandable that the tension adjustment assembly can slide along the fifth support frame 502. After initially determining the position of the tension adjustment assembly according to specific requirements, shake the runner 506. The gear shaft 505 and the runner 506 rotate synchronously. At the same time, the rack 507 reciprocates with the gear at the gear shaft 505, and the extended length of the cylindrical clamping shaft 509 also changes with the movement of the rack 507, so as to adjust the pre-tightening degree of the damping cable 703.

[0079] In addition, a tension clamping assembly is arranged on the cylindrical clamping shaft 509. The tension clamping assembly includes a first clamping block 510 and a second clamping block 511. The first clamping block 510 is fixed to the fifth support frame 502 by the third bolt 404 and the boat-shaped nut 405. The second clamping block 511 is fixed to the first clamping block 510 by two locking bolts 512. An arc-shaped hole is provided at the joint of the two clamping blocks, and a through hole is formed by the two arc-shaped plates. The diameter of the through hole is smaller than the diameter of the cylindrical clamping shaft 509. After the initial pre-tightening force of the damping cable 703 is adjusted, the two locking bolts 512 can be tightened to make the two clamping blocks clamp the cylindrical clamping shaft 509, so as to prevent the tensioning device 5 from moving.

[0080] It is easily understandable that each component in the tension support and the base support 4 can be an existing industrial aluminum profile, which is convenient for installation.

[0081] Reference Figure 9 、 Figure 10 and Figure 11As shown in the figure, the damper member 6 includes two sliding damper assemblies and a tension pulley 601. The tension pulley is arranged between the two sliding damper assemblies. The tension pulley 601 is similar to the redirecting pulley 105 arranged on the outer extension platform of the two-axis joint damper disc 1. A retaining piece 106 and a retaining ring 108 are arranged on the side of the tension pulley 601 to prevent the damping cable 703 from coming off the groove at the tension pulley 601. The damper member 6 is fixed to the mounting plate by bolts and nuts. The sliding damper assembly can automatically adjust the movement range of the damping cable according to the movement state of the robotic arm during the processing process and effectively apply a stable damping force to the damping cable.

[0082] Specifically, the sliding damper assembly includes two dampers arranged coaxially. The damper is selected as a viscous damper 602. The two viscous dampers 602 are symmetrically distributed along the first axis, and the first axis is perpendicular to the axis of the viscous damper 602. The viscous damper 602 is a magnetorheological damper, and the damping intensity can be actively controlled by changing the current according to the requirements of the robotic structure modal matching during use. A damper center block 603 is arranged at the symmetric center of the two viscous dampers 602. The damper center block 603 and the end of the piston rod are hinged by a pin shaft 604 and a split pin 109. Through the arrangement of the dampers, the sliding damper assembly provides a continuous damping internal force for the damping cable 703 during the operation of the robot and compensates for the change in the spatial position of the damping cable 703.

[0083] In this embodiment, a guiding hole is opened in the middle of the damper center block 603, and a damper center rod 605 is arranged in the guiding hole. The damper center rod 605 provides a sliding support for the sliding damper assembly. Tension springs 606 are respectively arranged on both sides of the damper center rod 605 along the first axis. The tension springs 606 are arranged through the damper center rod. One end of the damper center rod 605 is provided with a damper base 607, and the two are fixed by threaded connection. The damper base 607 is fixed to the mounting plate 409 by bolts and nuts. The other end of the damper center rod is provided with a damper limit block 608. A guiding hole is opened in the center of the damper limit block 608 for the non-fixed side of the damper center rod 605 to pass through. The tension springs are limited by the damper limit block. One of the two tension springs 606 is located between the damper limit block 608 and the damper center block 603, and the other is located between the damper center block 603 and the damper base 607, and is fixed by screwing into the limiting ear plates opened on each part;

[0084] The side of the damper limit block 608 is provided with a threaded hole, which is fixedly connected to the tension pulley 601 in the damper member 6 by a thread. Between the end of the viscous damper 602 and the damper limit block 608 and the damper base 607, two connecting rods 609 are respectively arranged. The end of the viscous damper 602 is hinged by using a pin shaft 604 and a split pin 109 through a connecting pad 610. Connecting lugs are arranged on the damper limit block 608 and the damper base 607, and the connecting rod 609 is hinged by passing the pin shaft 604 and the split pin 109 through the connecting lugs. After the four connecting rods 609 are installed, a rhombic hinged link mechanism is formed to ensure the stability of the damper member structure setting.

[0085] Reference Figure 11 and Figure 12 As shown, the threading method of the damping cable 703 is related to the number and positions of the main boom brackets 2 and the auxiliary boom brackets 3. In this embodiment, three main boom brackets 2 are provided, and two auxiliary boom brackets 3 are provided. The positions of the eyebolt 214 of the main boom brackets 2 and the auxiliary boom brackets 3 are adjusted to appropriate positions according to the actual application scenario, so as to ensure that the first eyebolt at the main boom bracket and the deflecting pulley 105 connected thereto are in the same plane (the plane is parallel to the side of the second main boom of the robot), preventing the damping cable 703 from slipping out of the groove during operation.

[0086] In addition, the closed cable assembly 7 further includes a first tension sensor 701, a second tension sensor 702, and a damping cable 703. The damping cable 703 can be divided into a first section of damping cable 7031 and a second section of damping cable 7032.

[0087] The layout method of the stiffness improvement mechanism includes the following steps: The first section of damping cable 7031 is sequentially passed through the eyebolt 214 on the main boom bracket 2 and the auxiliary boom bracket 3 (the threading method is cross-sequential threading), the first pulley at the first steering pulley bracket 8, and then connected to the second tension sensor 702. The second section of damping cable 7032 is sequentially passed through the pulley block 103 on the two-axis joint damping disc 1, the second pulley on the second steering pulley bracket 9, the fifth pulley on the tensioning device 5, and the tension pulley 601 on the damper member 6; The first end of the first section of damping cable 7031 and the first end of the second section of damping cable 7032 are connected by the first tension sensor 701, and the second end of the first section of damping cable 7031 and the second end of the second section of damping cable 7032 are connected by the second tension sensor 702.

[0088] To ensure better flutter suppression efficiency, the damping cable 703 can be made of plant fiber rope, chemical fiber rope, or steel wire rope. It can be understood that due to the material characteristics of the cable, there are significant differences in its modal frequencies. Before selection, according to the modal frequencies of the robot joints, multi-physics field simulation and experimental testing should be carried out to ensure the modal matching characteristics between the cable parameters and the joints, so that resonance is formed between the damping cable and the joints, thereby adsorbing the flutter energy on the joints to the cable for dissipation. There are already relatively mature technologies for the selection method of the damping cable 703, and no more introduction will be made here.

[0089] Embodiment 2

[0090] This embodiment discloses a working method for a stiffness improvement mechanism for a robot, including the following contents:

[0091] As Figure 11 and Figure 12 shown, the robot is in the zero-position attitude. Due to the pulling force provided by the tension spring 606 in the damper member 6, the tension pulley 601 is in the retracted state, and most of the piston rod of the viscous damper 602 extends, but it still provides damping internal force for the closed cable assembly 7. The tensioning device 5 abuts against the damping closed cable assembly 7 according to actual application needs and deforms it to provide an initial tensioning force.

[0092] Referring to Figure 13 shown, in this embodiment, the end effector of the robot is at the farthest point in the working space. The main arm bracket 2 and the sub-arm bracket 3 have no obvious position change due to being locked. The tension spring in the damper member 6 is stretched to the limit position due to being pulled by the closed cable assembly 7. At this time, the tension pulley 601 is in the fully stretched state, and most of the piston rod of the viscous damper 602 retracts, but it still provides damping internal force for the closed cable assembly 7. At this time, the damper member 6 makes a certain compensation for the spatial position change of the closed cable assembly 7, so there is no obvious change in the tension state of the damping cable 703.

[0093] Specifically, the tensioning device 5, the eye bolt 214, the redirecting pulley 105, the damper member 6, and the damping cable 703 can be adjusted according to actual needs until the readings of the first tension sensor 701 and the second tension sensor 702 are similar and within the preset range.

[0094] Ideally, the readings on the first tension sensor 701 and the second tension sensor 702 are exactly the same. However, in actual situations, the tensioning device 5 can only ensure the modal matching of the robot in the initial state. After the machining starts, due to the change in the spatial position of the damping cable 703 and the existence of friction on the contact surface, there will be a deviation in the readings on the first tension sensor 701 and the second tension sensor 702. Therefore, when installing the damping cable 703, a lubricating medium should be applied to its surface to reduce the friction coefficient. At the same time, an active feedback control strategy should be adopted to adjust the damping intensity of the viscous damper 602 in real time to achieve the real-time matching of the modes between the damping cable 703 and the robot joints.

[0095] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention can have various changes and modifications. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A stiffness enhancement mechanism for a robot, characterized in that: The robot comprises a base and a base bracket arranged at a first joint of the robot, wherein the base can rotatably support a first arm through the first joint, the first arm is connected to a second connecting rod arm through a second joint, a parallel connecting rod auxiliary arm is arranged on the side of the second connecting rod arm, the second connecting rod arm and the parallel connecting rod auxiliary arm are connected to a third arm through a third joint, and the third arm is connected to a fourth connecting rod; The base bracket supports the damper component, a two-axis joint damping disk is arranged at the second joint of the robot, a pulley block is arranged at the two-axis joint damping disk, a boom bracket is arranged at the second connecting rod boom of the robot, and a jib bracket is arranged at the parallel connecting rod jib of the robot. The damping cable is connected to the boom bracket and the jib bracket and then goes around the damper component, continues to pass through the tensioning device and bypasses the pulley block at the two-axis joint damping disk, and changes the torque direction of the damping cable through the pulley block, so that the damping cable provides a damping torque to the robot; The two-axis joint damping disk includes a pulley block base, the pulley block base is coaxially connected to the second joint, the pulley block base supports the pulley block, the pulley block includes a third pulley and a fourth pulley, a plurality of third pulleys are provided, and at least two fourth pulleys are provided. The plurality of third pulleys are arranged along the circumference of the pulley block base, the fourth pulley is located on the inner side of the third pulley, and a protruding arrangement is provided on one side of the pulley block base. A redirecting pulley is provided at the protruding part of the pulley block base, and the damping cable passes through part of the third pulley, the fourth pulley, another third pulley and the redirecting pulley in sequence, so that the damping cable is located at a section of the redirecting pulley and the boom bracket and has the same direction as the second connecting rod boom. The boom bracket is provided with at least two, the boom bracket is fixed to the circumferential direction of the boom of the second connecting rod, the eye bolt is installed on the side of the boom bracket, the damping cable is arranged through the eye bolt of the boom bracket, and the eye bolt is installed on the boom bracket through the boom eye fixing piece; The jib bracket is provided with at least one, and the jib bracket and the boom bracket are arranged alternately, the jib bracket is fixed to the circumferential direction of the parallel connecting rod jib, the eye bolt is installed on the side of the jib bracket, the damping rope passes through the eye bolt at the jib bracket, and the eye bolt is installed on the jib bracket through the jib eye fixing piece.

2. A stiffness enhancement mechanism for a robot according to claim 1, characterized in that: It also includes a first pulley and a second pulley, the first pulley is arranged at the hinge between the parallel link auxiliary arm and the second link main arm, the second pulley is arranged below the two-axis joint damping disk, and the damping cable is arranged to bypass the first pulley and the second pulley to change the direction of the damping cable through the first pulley and the second pulley.

3. A stiffness enhancement mechanism for a robot according to claim 2, characterized in that: The damping cable comprises two sections, the first section of the damping cable passes through the boom support, the jib support and the first pulley arrangement in sequence, the second section of the damping cable passes through the pulley block, the second pulley, the tensioning device and the damper component in sequence, the first section of the damping rope is connected to the second section of the damper through a tension sensor to form a closed cable assembly.

4. A stiffness enhancement mechanism for a robot according to claim 1, characterized in that: A stopper is also provided at the protrusion of the pulley block base, and the stopper connects the pulley shaft of the redirecting pulley and the protrusion of the pulley block base, so that a distance is set between the stopper and the redirecting pulley to limit the damping cable.

5. A stiffness enhancement mechanism for a robot according to claim 1, characterized in that: The structures of the boom lifting eye fixing piece and the jib lifting eye fixing piece are the same. Both of them include a convex cavity, a second nut is arranged in the convex cavity, and a third nut is arranged outside the convex cavity. The lifting eye bolt passes through the third nut and the second nut in sequence.

6. A stiffness enhancement mechanism for a robot according to claim 5, characterized in that: An adaptive clamping claw is arranged on the side of the boom bracket, and the adaptive clamping claw includes an adjusting bolt, which passes through a welding nut and the side of the boom bracket, and the welding nut is fixed to the side of the boom bracket. The end of the adjusting bolt is connected to a fastening hinge, and the fastening hinge is hingedly connected to the clamping claw leaf petal. The clamping claw leaf petal can rotate along the fastening hinge to adapt to the second connecting rod boom.

7. A stiffness enhancement mechanism for a robot according to claim 1, characterized in that: The damper component includes two sliding damping assemblies, a tensioning pulley is arranged between the two sliding damping assemblies, and the damping cable is arranged around the tensioning pulley. The sliding damping assembly includes two dampers arranged oppositely, and the telescopic ends of the two dampers are connected to the damper center block. The damper center rod is arranged through the damper center block. The damper center rod passes through one end of the damper center block and is connected to the base bracket, and the other end of the damper center rod passes through the damper limit block. The damper center rod is located on both sides of the damper center block and is respectively covered with tension springs. The fixed end of the damper is connected to the base bracket and the damper limit block through a connecting rod.

8. A stiffness enhancement mechanism for a robot according to claim 1, characterized in that: The tensioning device includes a tensioning bracket, which is installed on the base bracket. The position of the tensioning bracket relative to the base bracket is adjustable. The tensioning bracket supports a tensioning adjustment component and a tensioning clamping component. The tensioning adjustment component includes a moving part, which is slidably installed on the tensioning bracket. The moving part is connected to the cylindrical clamping shaft. A fifth pulley is arranged at one end of the cylindrical clamping shaft away from the moving part. The damping cable is arranged to bypass the fifth pulley so as to adjust the tension of the damping cable through the moving part. A stop part is arranged on one side of the fifth pulley.

9. A rigidity enhancement mechanism for a robot according to claim 8, characterized in that: The tensioning and clamping assembly clamps the cylindrical clamping shaft and is capable of locking the cylindrical clamping shaft. The fifth pulley is arranged below the damper component, and the cylindrical clamping shaft is arranged tilted upward relative to the bottom of the base bracket.

10. A rigidity enhancement mechanism for a robot according to claim 1, characterized in that: The base support includes a bottom frame, which supports a vertical frame, and the vertical frame supports a mounting plate. The mounting plate is provided with multiple layers of mounting holes, and the mounting holes of two adjacent layers of mounting holes are staggered. The damper component is installed on the mounting plate through the mounting holes.

11. A working method for a stiffness enhancement mechanism of a robot according to any one of claims 1 to 10, characterized in that: It includes the following: A base bracket is arranged at the first joint of the robot, the base bracket supports the damper component, a two-axis joint damping disk is arranged at the second joint, a pulley block is arranged at the two-axis joint damping disk, a big arm bracket is arranged at the second connecting rod big arm, and a jib bracket is arranged at the parallel connecting rod jib; The damping cable is connected to the boom support and the auxiliary arm support and then goes around the damper component, and then passes through the tensioning device and around the pulley block at the two-axis joint damping plate; The robot is in a zero-position posture, the damper component provides a damping internal force for the damping cable, and the tensioning device abuts against the damping cable and deforms it to provide an initial tensioning force according to actual application requirements; During the working process of the first arm, the second link arm, the parallel link jib and the third arm of the robot, a damping torque is introduced to the second joint, the second link arm and the parallel link jib through the damping cable to realize the dissipation of the flutter energy of the joint structure.

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