Variable stiffness mechanism and robot

Abstract

The rigidity-variable mechanism comprises a rack, an output assembly and a driving assembly, the output assembly comprises a guide wheel frame, a first guide wheel, a second guide wheel and a rigidity-adjusting rope, the guide wheel frame is rotatably connected to the rack, the first guide wheel and the second guide wheel are both arranged on the guide wheel frame, and the rigidity-adjusting rope is wound on the first guide wheel and the second guide wheel; the driving assembly comprises a first wheel disc, a second wheel disc and a movable part, the first wheel disc and the second wheel disc are rotationally connected to the rack, the movable part is connected to the first wheel disc and the second wheel disc, the movable part and the first guide wheel are sequentially arranged in the radial direction of the first wheel disc, and the movable part abuts against the rigidity adjusting rope; when the first wheel disc and the second wheel disc rotate relatively, the movable piece moves in the radial direction of the first wheel disc, and the movable piece drives the guide wheel frame to rotate through the rigidity adjusting rope. In the invention, the transmission ratio between the driving assembly and the guide wheel frame is adjusted by changing the position of the movable part, so that the rigidity between the guide wheel frame and the driving assembly is adjusted.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of robots, in particular to a variable stiffness mechanism and a robot. BACKGROUND

[0002] With the development of robot technology, the behavior characteristics of robots have developed from simple interaction with parts to natural interaction with the environment, people and other robots. Traditional industrial robot joint drives usually adopt rigid transmission mechanisms, which can achieve high position control accuracy and response speed, but lack flexible units in the transmission chain, which has the problem of insufficient safety in human-machine-environment interaction. Therefore, a joint drive with a variable stiffness mechanism is proposed, which can be changed according to application requirements, and the stiffness of the transmission system can be adjusted in real time. By reducing the stiffness of the mechanism, the torque sensing sensitivity and reverse driving performance are improved, and by increasing the stiffness of the mechanism, the force control bandwidth and carrying capacity are improved.

[0003] The structural form of the existing variable stiffness mechanism mainly includes bionic antagonistic type, spring preloading type, variable transmission ratio type and elastic element structure adjustment type. Among them, the bionic antagonistic type and the spring preloading type variable stiffness mechanism have the problems of high energy consumption of stiffness adjustment and small stiffness adjustment range; the variable transmission ratio type and the elastic element structure adjustment type have the problems of complex structure, cannot realize power superposition of joint motor and stiffness adjustment motor, and low power density. SUMMARY

[0004] The purpose of the present application is to provide a variable stiffness mechanism and a robot, which solves the problems of high energy consumption, low adjustment efficiency and low power density of stiffness adjustment.

[0005] To achieve the purpose of the present application, the present application provides the following technical solutions:

[0006] In a first aspect, the present application provides a variable stiffness mechanism, comprising:

[0007] a rack;

[0008] an output assembly comprising a guide wheel rack, a first guide wheel, a second guide wheel and a stiffness adjustment rope, the guide wheel rack being rotatably connected to the rack, the first guide wheel and the second guide wheel being arranged on the guide wheel rack, and the stiffness adjustment rope being wound on the first guide wheel and the second guide wheel;

[0009] a drive assembly comprising a first pulley, a second pulley and a movable piece, the first pulley and the second pulley being rotatably connected to the rack, the movable piece being connected to the first pulley and the second pulley, the movable piece and the first guide wheel being arranged along the radial direction of the first pulley in sequence, and the movable piece abutting against the stiffness adjustment rope;

[0010] When the first wheel and the second wheel rotate relative to each other, the movable element moves along the radial direction of the first wheel, and the movable element drives the guide wheel frame to rotate through the rigidity adjusting rope.

[0011] In one embodiment, the first wheel is provided with a straight slot extending along the radial direction, the second wheel is provided with an arc-shaped slot, and the movable element is inserted into the arc-shaped slot and the straight slot;

[0012] When the first wheel and the second wheel rotate relative to each other, the arc-shaped slot drives the movable element to move along the straight slot to adjust the distance between the movable element and the first guide wheel.

[0013] In one embodiment, the movable element includes a shaft body, a first flange, and a second flange, the first flange and the second flange are protruding from the peripheral wall of the shaft body, and the shaft body abuts against the slot wall of the arc-shaped slot;

[0014] The first flange is square-shaped, the first flange abuts against the slot wall of the straight slot, and the second flange is clamped between the first wheel and the second wheel.

[0015] In one embodiment, the frame is rotationally connected with a mounting shaft, the guide wheel frame is fixed on the mounting shaft, and the first guide wheel is provided in plurality, and the plurality of first guide wheels are arranged at intervals in the circumferential direction of the mounting shaft;

[0016] The second guide wheel is provided in plurality, and the plurality of second guide wheels are arranged at the periphery of the plurality of first guide wheels, and the rigidity adjusting rope is wound around the plurality of first guide wheels and the plurality of second guide wheels;

[0017] The rigidity adjusting rope on at least one first guide wheel and two second guide wheels surrounds an accommodation space, and the movable element is arranged in the accommodation space.

[0018] In one embodiment, the movable element is provided in plurality, the straight slot is provided in plurality, the arc-shaped slot is provided in plurality, and the plurality of movable elements, the plurality of straight slots, the plurality of arc-shaped slots, and the plurality of first guide wheels are arranged one-to-one;

[0019] The number of the second guide wheels is twice the number of the first guide wheels.

[0020] In one embodiment, the output assembly further includes a fixed seat, a connecting rod, an elastic element, and a pre-tightening bolt, the connecting rod connects the guide wheel frame and the fixed seat, the pre-tightening bolt is threadedly connected with the fixed seat, the first end of the elastic element is connected with the fixed seat, the second end of the elastic element is connected with the first end of the rigidity adjusting rope, and the second end of the rigidity adjusting rope is connected with the pre-tightening bolt.

[0021] In one embodiment, the variable stiffness mechanism further comprises a first encoder, the first encoder is arranged on the frame, a magnetic steel is arranged on the mounting shaft, and the first encoder measures the relative rotation angle between the guide wheel frame and the frame through the magnetic steel.

[0022] In one embodiment, the variable stiffness mechanism further comprises a second encoder, the second encoder is arranged on the second pulley, a first magnetic ring is arranged on the mounting shaft, a second magnetic ring is arranged on the first pulley, the second encoder measures the relative rotation angle between the guide wheel frame and the first pulley or the second pulley through the first magnetic ring, and the second encoder measures the relative rotation angle between the first pulley and the second pulley through the second magnetic ring.

[0023] In one embodiment, the drive assembly further comprises a first drive machine and a second drive machine, a first drive rope is arranged around the first pulley, and a second drive rope is arranged around the second pulley, the first drive rope is connected to the output end of the first drive machine, and the second drive rope is connected to the output end of the second drive machine.

[0024] In a second aspect, the application also provides a robot comprising the variable stiffness mechanism according to any one of the various embodiments of the first aspect.

[0025] Compared with the prior art, the application has at least the following beneficial effects:

[0026] 1. In the application, the stiffness adjusting rope is arranged around the first guide wheel and the second guide wheel, and the movable member is connected to the first pulley and the second pulley, the movable member and the first guide wheel are arranged along the radial direction of the first pulley in sequence, and the movable member abuts against the stiffness adjusting rope. When the first pulley and the second pulley rotate relative to each other, the movable member moves along the radial direction of the first pulley. The change of the position of the movable member changes the position of the abutting point between the stiffness adjusting rope and the movable member, thereby changing the transmission ratio between the first pulley and the guide wheel frame, so as to adjust the stiffness between the guide wheel frame and the drive assembly. Moreover, the stiffness adjusting rope is arranged around the first guide wheel and the second guide wheel, and the guide wheel frame rotates under the action of the stiffness adjusting rope. The change of the stress state of the stiffness adjusting rope is transmitted to the guide wheel frame, so that the drive assembly and the guide wheel frame have a flexible unit in the transmission chain, thereby improving the safety of human-machine-environment interaction.

[0027] 2. In the application, the mechanism combines the first guide wheel, the second guide wheel, the first pulley, the second pulley, the movable member and other components, converts the relative rotation of the first pulley and the second pulley in the drive assembly into a change in the transmission ratio between the first pulley and the guide wheel frame through the movable member, and finally realizes the rotation of the guide wheel frame through the stiffness adjusting rope. The stiffness adjusting process only needs to resist a small component force of the action force generated by the deformation of the stiffness adjusting rope, so as to realize a high stiffness adjusting energy efficiency.

[0028] 3、In the application, when the first disc and the second disc move synchronously, the position of the movable part in the radial direction of the first disc does not change, the transmission ratio between the first disc and the guide wheel frame does not change, the rigidity of the mechanism remains unchanged, and the driving force of the first disc and the second disc can act on the guide wheel frame together to realize the superimposed output of the two driving forces; when the first disc and the second disc rotate relatively, the position of the movable part changes, the transmission ratio between the first disc and the guide wheel frame changes, so that the rigidity of the mechanism changes, and the driving force of the first disc and the second disc will act on the torque output and the rigidity adjustment. That is, the driving force of the first disc and the second disc can be used to drive the guide wheel frame to rotate, and also can realize the adjustment of the rigidity, so as to improve the power density of the variable rigidity mechanism as a whole.

[0029] 4、In the application, the variable rigidity mechanism adopts the driving mode of the first disc and the second disc, and the positions of the two motors can be arranged arbitrarily through the rope transmission mode. When the variable rigidity structure is used in a robot, not only the joint structure of the robot can be simplified, but also the inertia of the joint end can be reduced, so as to improve the overall dynamic performance of the robot system. BRIEF DESCRIPTION OF DRAWINGS

[0030] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed to be used in the description of the embodiments or the prior art will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor.

[0031] Figure 1 It is a perspective view of the variable rigidity mechanism of one embodiment of the present application;

[0032] Figure 2 It is an exploded view of the variable rigidity mechanism of one embodiment of the present application;

[0033] Figure 3 It is a perspective view of the driving assembly of one embodiment of the present application;

[0034] Figure 4 It is an exploded view of the driving assembly of one embodiment of the present application;

[0035] Figure 5 It is a perspective view of part of the structure of the variable rigidity mechanism of one embodiment of the present application;

[0036] Figure 6 It is an exploded view of part of the structure of the variable rigidity mechanism of one embodiment of the present application;

[0037] Figure 7 It is a front view of the variable rigidity mechanism of one embodiment of the present application;

[0038] Figure 8 For Figure 7 Figure 2 is a cross-sectional view along line A-A in Figure 1.

[0039] Explanation of reference signs:

[0040] 100, frame; 110, mounting shaft; 111, magnetic steel; 112, first magnetic ring; 200, output assembly; 210, guide wheel frame; 211, locking groove; 220, first guide wheel; 230, second guide wheel; 240, stiffness adjusting rope; 250, accommodating space; 260, fixing seat; 270, connecting rod; 280, elastic member; 290, pre-tightening bolt; 300, driving assembly; 310, first pulley; 311, straight groove; 312, second magnetic ring; 320, second pulley; 321, arc-shaped groove; 330, movable member; 331, shaft body; 332, first flange; 333, second flange; 340, first driving rope; 350, second driving rope; 400, first encoder; 500, second encoder. DETAILED DESCRIPTION

[0041] The following is a specific embodiment of the present application and further describes the technical solutions of the present application in conjunction with the drawings, but the present application is not limited to these embodiments.

[0042] With reference to Figure 1 , Figure 2 and Figure 3 , the present application provides a stiffness adjusting mechanism, which comprises a frame 100, an output assembly 200 and a driving assembly 300.

[0043] The frame 100 is the basic support structure of the entire stiffness adjusting mechanism, and provides a stable mounting platform for the output assembly 200 and the driving assembly 300, so as to ensure the relative position accuracy and the accuracy of the movement relationship between the components.

[0044] The output assembly 200 comprises a guide wheel frame 210, a first guide wheel 220, a second guide wheel 230 and a stiffness adjusting rope 240. The guide wheel frame 210 is rotatably connected to the frame 100, and the guide wheel frame 210 serves as a mounting carrier for the first guide wheel 220 and the second guide wheel 230. The first guide wheel 220 and the second guide wheel 230 are both arranged on the guide wheel frame 210, and the stiffness adjusting rope 240 is wound around the first guide wheel 220 and the second guide wheel 230. The stiffness adjusting rope 240 is a rope-like component with certain flexibility and strength, and serves as a medium for transmitting force and adjusting stiffness. The stiffness adjusting rope 240 can be a steel wire rope, a nylon rope or the like.

[0045] The driving assembly 300 comprises a first wheel disc 310, a second wheel disc 320 and a movable piece 330, the first wheel disc 310 and the second wheel disc 320 are rotatably connected to the rack 100, the movable piece 330 is connected to the first wheel disc 310 and the second wheel disc 320, the movable piece 330 and the first guide wheel 220 are sequentially arranged along the radial direction of the first wheel disc 310, and the movable piece 330 abuts against the tuning rigid rope 240; when the first wheel disc 310 and the second wheel disc 320 relatively rotate, the movable piece 330 moves along the radial direction of the first wheel disc 310, and the movable piece 330 drives the guide wheel frame 210 to rotate through the tuning rigid rope 240. The first wheel disc 310 and the second wheel disc 320 are main rotating components of the driving assembly 300, and they serve as the mounting basis of the movable piece 330. Through the relative rotation of the first wheel disc 310 and the second wheel disc 320, the movable piece 330 is driven to move along the radial direction of the first wheel disc 310, so as to change the abutting position of the movable piece 330 and the tuning rigid rope 240, realize the adjustment of the transmission ratio between the first wheel disc 310 and the guide wheel frame 210, and change the mechanism stiffness. The tuning rigid rope 240 is wound around the first guide wheel 220 and the second guide wheel 230, the guide wheel frame 210 will rotate under the action force of the tuning rigid rope 240, and the change of the stress state of the tuning rigid rope 240 will be transmitted to the guide wheel frame 210, so that the driving assembly 300 and the guide wheel frame 210 have a flexible unit in the transmission link, and the safety of human-machine-environment interaction is improved.

[0046] In the present application, when the first wheel disc 310 and the second wheel disc 320 move synchronously, the position of the movable piece 330 in the radial direction of the first wheel disc 310 does not change, the mechanism stiffness remains unchanged, and the driving force of the first wheel disc 310 and the second wheel disc 320 can jointly act on the guide wheel frame 210 to realize the superimposed output of the two driving forces; when the first wheel disc 310 and the second wheel disc 320 relatively rotate, the position of the movable piece 330 changes and the mechanism stiffness changes, and the driving force of the first wheel disc 310 and the second wheel disc 320 will act on the torque output and the stiffness adjustment. That is, the driving force of the first wheel disc 310 and the second wheel disc 320 can be used to drive the guide wheel frame 210 to rotate, and can also realize the adjustment of the stiffness between the first wheel disc 310 and the guide wheel frame 210, thereby improving the power density of the variable stiffness mechanism as a whole.

[0047] Meanwhile, the variable stiffness mechanism combines the first guide wheel 220, the second guide wheel 230, the first wheel disc 310, the second wheel disc 320 and the movable piece 330, and converts the relative rotation of the first wheel disc 310 and the second wheel disc 320 in the driving assembly 300 into the transmission ratio change between the first wheel disc 310 and the guide wheel frame 210 through the movable piece 330, and then transmits it to the guide wheel frame 210 through the tuning rigid rope 240, so as to finally realize the rotation of the guide wheel frame 210. The stiffness adjustment process only needs to resist a small part of the action force generated by the deformation of the tuning rigid rope 240, so a high stiffness adjustment energy efficiency can be realized.

[0048] The first wheel disc 310 is provided with a straight slot 311 extending in the radial direction, the second wheel disc 320 is provided with an arc-shaped slot 321, and the movable element 330 is inserted into the arc-shaped slot 321 and the straight slot 311; when the first wheel disc 310 and the second wheel disc 320 rotate relative to each other, the arc-shaped slot 321 drives the movable element 330 to move along the straight slot 311, so as to adjust the distance between the movable element 330 and the first guide wheel 220.

[0049] The straight slot 311 is a linear guide structure extending in the radial direction of the first wheel disc 310, which provides a constraint path for the radial movement of the movable element 330. The arc-shaped slot 321 is a curved guide structure provided on the second wheel disc 320, which can be realized by a circular arc-shaped or spiral-shaped slot, and its function is to convert the relative rotational motion of the first wheel disc 310 and the second wheel disc 320 into the radial displacement of the movable element 330 through cooperation with the straight slot 311.

[0050] Specifically, when the first wheel disc 310 and the second wheel disc 320 rotate relative to each other, the slot wall of the arc-shaped slot 321 exerts a lateral thrust on the movable element 330, forcing the movable element 330 to move along the extension direction of the straight slot 311. Due to the radial extension characteristic of the straight slot 311, the moving direction of the movable element 330 always coincides with the radial direction of the first wheel disc 310, and the curvature of the arc-shaped slot 321 determines the corresponding relationship between the displacement of the movable element 330 and the relative rotation angle of the two wheel discs. By adjusting the relative rotation angle of the two wheel discs, the position of the movable element 330 can be accurately controlled, thereby changing the distance between the movable element 330 and the first guide wheel 220, and finally realizing the dynamic adjustment of the tension of the rigid rope 240.

[0051] The present application directly converts the rotational motion of the first wheel disc 310 and the second wheel disc 320 into the radial displacement of the movable element 330 through the cooperation of the straight slot 311 and the arc-shaped slot 321, simplifies the transmission structure, reduces the friction loss and assembly error of the intermediate links, improves the adjustment accuracy and response speed, and can realize the accurate control of the position of the movable element 330 with a more compact structure, solving the problems of rigidity adjustment hysteresis and high energy consumption caused by the complexity of the transmission chain in the traditional variable rigidity mechanism.

[0052] It should be noted that the first wheel disc 310 is connected with the guide wheel frame 210 through the movable element 330, the first wheel disc 310 moves relative to the second wheel disc 320, so that the movable element 330 moves along the radial direction of the first wheel disc 310, and the transmission ratio between the first wheel disc 310 and the guide wheel frame 210 can be changed through the displacement of the movable element 330, so as to realize the rigidity adjustment of the mechanism. And the movable element 330 drives the guide wheel frame 210 to rotate through the abutting of the rigidity adjustment rope 240, so that the movable element 330 and the guide wheel frame 210 have a flexible unit in the transmission link, which improves the safety of human-machine-environment interaction. Specifically, when the movable element 330 moves towards the first guide wheel 220, the transmission ratio between the first wheel disc 310 and the guide wheel frame 210 decreases, and the rigidity decreases; when the movable element 330 moves away from the first guide wheel 220, the transmission ratio between the first wheel disc 310 and the guide wheel frame 210 increases, and the rigidity increases.

[0053] Wherein, the lock slot 211 can be arranged on the guide wheel frame 210, when the movable element 330 moves into the lock slot 211, the rigidity of the rigidity adjustment mechanism tends to be rigid as a whole, so that the rigidity adjustment mechanism can realize a larger rigidity range. And because the angle between the moving direction of the movable element 330 and the force direction of the rigidity adjustment rope 240 acting on the movable element 330 is small, the rigidity adjustment process does not need to exert a large adjustment torque, and high energy efficiency rigidity adjustment of the rigidity adjustment mechanism can be realized.

[0054] Reference Figure 4 , Figure 5 and Figure 6 , the movable element 330 includes a shaft body 331, a first flange 332 and a second flange 333, the first flange 332 and the second flange 333 are protruded on the peripheral wall of the shaft body 331, and the shaft body 331 abuts with the slot wall of the arc-shaped slot 321; the first flange 332 is square-shaped, the first flange 332 abuts with the slot wall of the straight slot 311, and the second flange 333 is clamped between the first wheel disc 310 and the second wheel disc 320. Wherein, the shaft body 331 is a cylindrical structure extending along the axis, the first flange 332 is a square-shaped protruding structure extending outward along the circumference of the shaft body 331, and the machining mode of being integrally formed with the shaft body 331 can be specifically adopted, which is used to limit the moving direction of the movable element 330 in the straight slot 311. The second flange 333 is a ring-shaped protruding structure extending outward along the circumference of the shaft body 331, and the split assembly or integral machining mode can be specifically adopted, which is used to limit the axial displacement of the movable element 330 between the wheel discs.

[0055] Specifically, when the first disc 310 and the second disc 320 rotate relative to each other, the shaft body 331 of the movable element 330 is guided to move by the arc-shaped groove 321. The square structure of the first flange 332 is in contact with the groove wall of the straight groove 311, ensuring that the movable element 330 only slides in the radial direction and does not rotate. The annular structure of the second flange 333 is embedded in the gap between the first disc 310 and the second disc 320, forming axial limiting, preventing the movable element 330 from being separated from the first disc 310 and the second disc 320 during movement, and improving the stability of the movable element installation.

[0056] The present application eliminates the rotational freedom of the movable element 330 by the cooperation of the square first flange 332 and the straight groove 311, and the second flange 333 avoids axial displacement deviation, significantly improving the stability and adjustment accuracy of the movement of the movable element 330.

[0057] The mounting shaft 110 is rotatably connected to the frame 100, and the guide wheel frame 210 is fixedly arranged on the mounting shaft 110. The first guide wheel 220 is provided in a plurality of numbers, and the plurality of first guide wheels 220 are arranged at intervals in the circumferential direction of the mounting shaft 110. The second guide wheel 230 is provided in a plurality of numbers, and the plurality of second guide wheels 230 are arranged outside the plurality of first guide wheels 220. The tuning string 240 is wound around the plurality of first guide wheels 220 and the plurality of second guide wheels 230. At least one first guide wheel 220 and two second guide wheels 230 form a containing space 250 around the tuning string 240, and the movable element 330 is arranged in the containing space.

[0058] The mounting shaft 110 is a shaft body 331 for fixing the guide wheel frame 210 and transmitting rotational motion. The mounting shaft 110 can be connected to the frame 100 through a bearing to realize low-friction rotation of the guide wheel frame 210. The guide wheel frame 210 is fixedly arranged on the mounting shaft 110 to ensure that the guide wheel frame 210 rotates synchronously with the mounting shaft 110. The plurality of first guide wheels 220 are arranged at intervals in the circumferential direction of the mounting shaft 110, and can be arranged at equal angles to form a symmetrical layout to balance the stress. The plurality of second guide wheels 230 are arranged outside the plurality of first guide wheels 220 to form an inner-outer two-layer guide wheel structure.

[0059] Specifically, when the movable element 330 drives the guide wheel frame 210 to rotate, the mounting shaft 110 rotates as a whole with the guide wheel frame 210, the plurality of first guide wheels 220 form a plurality of winding points in the circumferential direction, and the second guide wheel 230 forms a stress point in the periphery. The winding path of the tuning string 240 between the first guide wheel 220 and the second guide wheel 230 forms a plurality of containing spaces 250, and the movable element 330 enters the space and contacts the tuning string 240. When the movable element 330 is controlled by the driving assembly 300 to produce radial displacement, the containing space 250 is increased by extruding the tuning string 240, and the cooperation between the tuning string 240 and the movable element makes the driving assembly 300 and the transmission link of the guide wheel frame 210 flexible.

[0060] The application forms a grid winding system through multiple guide wheels distributed in a circumferential direction, realizes more adjustment positions in the same space, and significantly improves the continuity and stability of stiffness adjustment through the staggered tension network formed by the stiffness adjustment ropes 240 due to the double-layer guide wheel layout.

[0061] In an embodiment, multiple movable members 330 are provided, multiple straight grooves 311 are provided, multiple arc grooves 321 are provided, and the multiple movable members 330, the multiple straight grooves 311, the multiple arc grooves 321, and the multiple first guide wheels 220 are one-to-one correspondingly arranged; and the number of the second guide wheels 230 is twice the number of the first guide wheels 220.

[0062] Specifically, the multiple movable members 330 are respectively embedded in the corresponding straight grooves 311 and arc grooves 321, and when the first disc 310 and the second disc 320 rotate relative to each other, each movable member 330 moves independently along the straight groove 311 under the drive of the arc groove 321, thereby respectively adjusting the distance between the multiple movable members 330 and the corresponding first guide wheels 220. The stiffness adjustment ropes 240 are wound around the multiple first guide wheels 220 and the double number of second guide wheels 230, forming multiple independent tensioning paths. The displacement of each movable member 330 is transmitted to the corresponding guide wheel set through the stiffness adjustment ropes 240, driving the guide wheel frame 210 to rotate.

[0063] The application can expand the winding path of the stiffness adjustment ropes 240 while maintaining compact structure through the cooperative work of multiple independent adjustment units, effectively enhance the flexibility and stability of the stiffness adjustment mechanism, and solve the problems of small stiffness adjustment range and low power density in the prior art.

[0064] Reference Figure 6 , Figure 7 and Figure 8 The output assembly 200 further includes a fixed seat 260, a connecting rod 270, an elastic member 280, and a pre-tightening bolt 290. The connecting rod 270 connects the guide wheel frame 210 and the fixed seat 260. The pre-tightening bolt 290 is threadedly connected with the fixed seat 260. The first end of the elastic member 280 is connected with the fixed seat 260, and the second end of the elastic member 280 is connected with the first end of the stiffness adjustment rope 240. The second end of the stiffness adjustment rope 240 is connected with the pre-tightening bolt 290.

[0065] The fixed seat 260 is fixed on the guide wheel frame 210 through the connecting rod 270. The elastic member 280 is an element with elastic deformation capability, which can be a coil spring, a disc spring, or a rubber member, and is used to store and release energy to adjust the tension of the stiffness adjustment rope 240. The pre-tightening bolt 290 is a fastener for adjusting the initial tension of the stiffness adjustment rope 240. The pre-tightening bolt 290 can be threadedly connected with the fixed seat 260, and the pre-tightening force of the elastic member 280 can be adjusted by rotating the pre-tightening bolt 290 to change the stretching length of the stiffness adjustment rope 240.

[0066] Specifically, the deformation amount of the elastic member 280 is transmitted to the guide wheel frame 210 through the tuning stiffness rope 240, and the pre-tightening bolt 290 adjusts the initial tension of the tuning stiffness rope 240 to change the pre-compression amount of the elastic member 280, thereby controlling the initial stiffness of the variable stiffness mechanism. For example, when the pre-tightening bolt 290 is unscrewed, the tuning stiffness rope 240 is tightened, the pre-compression amount of the elastic member 280 is increased, and the initial stiffness of the variable stiffness mechanism is increased; when the pre-tightening bolt 290 is screwed in, the tuning stiffness rope 240 is relaxed, the pre-compression amount of the elastic member 280 is reduced, and the initial stiffness of the variable stiffness mechanism is reduced.

[0067] The present application can change the pre-tightening force of the tuning stiffness rope 240 and the elastic member 280 through the cooperation of the elastic member 280 and the pre-tightening bolt 290, can realize offline adjustment of the stiffness range of the variable stiffness mechanism, and improves the applicability of the variable stiffness mechanism to different scenes.

[0068] In an embodiment, the variable stiffness mechanism further comprises a first encoder 400, which is arranged on the rack 100, and a magnetic steel 111 is arranged on the mounting shaft 110. The first encoder 400 measures the relative rotation angle between the guide wheel frame 210 and the rack 100 through the magnetic steel 111.

[0069] The first encoder 400 is a sensor for measuring the angular displacement of a rotating component, which can be implemented by an optical encoder or a magnetic encoder. It generates an electrical signal by detecting the position change of the magnetic steel 111 to realize non-contact angle measurement. The magnetic steel 111 is a magnetic component made of permanent magnetic material, which can be implemented by neodymium iron boron, ferrite material or samarium cobalt magnetic steel. The magnetic steel 111 can be fixed at one end of the mounting shaft 110 and form a magnetic field coupling relationship with the first encoder 400 to convert mechanical rotation into identifiable magnetic signals.

[0070] Specifically, the mounting shaft 110 is fixedly connected with the guide wheel frame 210, and when the guide wheel frame 210 is driven to rotate by the tuning stiffness rope 240, the mounting shaft 110 drives the magnetic steel 111 to rotate synchronously. The first encoder 400 detects the magnetic field change of the magnetic steel 111 to obtain the rotation angle data of the guide wheel frame 210 relative to the rack 100 in real time. The rotation angle data can be used to feedback control the relative rotation amount of the first disc 310 and the second disc 320 in the driving assembly 300, so as to accurately adjust the radial displacement of the movable member 330 and realize dynamic adjustment of the stiffness of the variable stiffness mechanism.

[0071] The variable stiffness mechanism further comprises a second encoder 500 arranged on the second pulley 320. A first magnetic ring 112 is arranged on the mounting shaft 110, and a second magnetic ring 312 is arranged on the first pulley 310. The second encoder 500 measures the relative rotation angle between the trolley 210 and the first pulley 310 or the second pulley 320 through the first magnetic ring 112, and measures the relative rotation angle between the first pulley 310 and the second pulley 320 through the second magnetic ring 312.

[0072] The second encoder 500 is a sensor device for detecting the relative rotation angle between rotating components, which can be implemented by a Hall encoder or an optical encoder, and converts the change of magnetic field or light signal into an electric signal. The first magnetic ring 112 is an annular magnetic element arranged on the mounting shaft 110, which can be implemented by a multi-pole magnetic ring, and the magnetic field distribution thereof changes with the rotation of the mounting shaft 110 to provide a detection reference for the encoder. The second magnetic ring 312 is an annular magnetic element arranged on the first pulley 310, and the magnetic field distribution thereof changes with the rotation of the first pulley 310 to reflect the relative position relationship between the first pulley 310 and the second pulley 320.

[0073] Specifically, the mounting shaft 110 is fixedly connected with the trolley 210. When the trolley 210 is driven to rotate by the adjusting cable 240, the first magnetic ring 112 rotates synchronously with the mounting shaft 110. The second encoder 500 captures the change of the magnetic field of the first magnetic ring 112 to calculate the rotation angle offset of the trolley 210 relative to the first pulley 310 or the second pulley 320. Meanwhile, when the first pulley 310 and the second pulley 320 rotate relative to each other, the second magnetic ring 312 rotates with the first pulley 310. The second encoder 500 determines the relative rotation angle between the first pulley 310 and the second pulley 320 by comparing the magnetic field phase difference between the second magnetic ring 312 and a fixed reference point. Thus, the second encoder 500 can simultaneously obtain the relative motion state between the trolley 210 and the driving assembly 300 and the relative position between the first pulley 310 and the second pulley 320 in the driving assembly 300, to provide real-time feedback data for the stiffness adjustment of the variable stiffness mechanism and improve the control accuracy of the stiffness adjustment of the variable stiffness mechanism.

[0074] In an embodiment, the driving assembly 300 further comprises a first driving machine (not shown) and a second driving machine (not shown), the first driving rope 340 is wound around the first wheel disc 310, and the second driving rope 350 is wound around the second wheel disc 320, the first driving rope 340 is connected to the output end of the first driving machine, and the second driving rope 350 is connected to the output end of the second driving machine. The first driving machine is a power device for driving the first wheel disc 310 to rotate, which can be implemented by a servo motor or a stepping motor, and the torque is transmitted through the output end connection driving rope. The second driving machine has the same structure as the first driving machine and is independently controlled, and the two drive different wheel discs to realize synchronous or differential motion. The first driving rope 340 is a flexible transmission component wound and fixed around the circumference of the first wheel disc 310, which can be implemented by a steel wire rope or a synthetic fiber rope. The second driving rope 350 is a flexible transmission component wound and fixed around the circumference of the second wheel disc 320, and the second driving rope 350 and the first driving rope 340 can have the same material and structure, and the relative rotation control between the first wheel disc 310 and the second wheel disc 320 is realized through independent transmission of the first driving rope 340 and the second driving rope 350.

[0075] Specifically, when the first driving machine winds the first driving rope 340 through the output end, it drives the first wheel disc 310 to rotate around its axis, and when the second driving machine winds the second driving rope 350 through the output end, it drives the second wheel disc 320 to rotate around its axis. The first wheel disc 310 and the second wheel disc 320 can rotate synchronously or relatively, and the relative rotation of the first wheel disc 310 and the second wheel disc 320 is converted into the radial displacement of the movable part 330 through the cooperation of the arc-shaped groove 321 and the straight groove 311, thereby changing the distance between the movable part 330 and the first guide wheel 220. In this process, the independent control of the first driving machine and the second driving machine allows the first wheel disc 310 and the second wheel disc 320 to rotate at different speeds.

[0076] The first driving machine and the second driving machine are independently wound with the first driving rope 340 and the second driving rope 350, and the output power of the first driving machine and the second driving machine is directly superimposed on the stiffness adjusting system and the driving mechanism for driving the guide wheel frame 210 to rotate, thereby improving the power density of the variable stiffness mechanism as a whole. The variable stiffness mechanism adopts the driving mode of the first wheel disc 310 and the second wheel disc 320, and the first wheel disc 310 and the second wheel disc 320 can be arranged at any position through the transmission mode of the first driving rope 340 and the second driving rope 350. When the variable stiffness structure is used in a robot, not only can the joint structure of the robot be simplified, but also the inertia of the joint end can be reduced, thereby improving the overall dynamic performance of the robot system.

[0077] The variable stiffness mechanism provided in the application can realize online continuous high-energy-efficiency adjustment of the stiffness of the mechanism and offline adjustment of the stiffness range of the mechanism. By driving the differential motion of the first disc 310 and the second disc 320, the position adjustment of the movable part 330 can be realized, and then the online continuous high-energy-efficiency adjustment of the stiffness of the mechanism is realized. By rotating the pre-tightening bolt 290 to change the preload of the elastic part 280, the offline adjustment of the stiffness range of the variable stiffness mechanism can be realized, and then the variable stiffness mechanism is suitable for different application requirements.

[0078] The application also provides a robot comprising the variable stiffness mechanism. The robot is a mechanical device capable of adjusting the stiffness of a joint through the variable stiffness mechanism, and can be a mechanical arm, a bionic robot or a collaborative robot. The variable stiffness mechanism changes the stiffness of the joint through the cooperation of the first disc 310, the second disc 320 and the movable part 330.

[0079] Specifically, the robot controls the movable part 330 to move along the radial direction of the disc through the driving assembly 300 in the variable stiffness mechanism. The position change of the movable part 330 changes the position of the abutting point of the stiffness-adjusting rope 240 and the movable part 330, thereby changing the transmission ratio between the first disc 310 and the guide pulley frame 210, so as to realize the adjustment of the stiffness between the guide pulley frame 210 and the driving assembly 300. The movable part 330 is in contact with the stiffness-adjusting rope 240, and then the guide pulley frame 210 is driven to rotate around the frame 100. The rotation of the guide pulley frame 210 is transmitted to the joint of the robot through the output assembly 200, so that the stiffness of the joint is adjusted with the position change of the movable part 330.

[0080] The application realizes the dynamic adjustment of the stiffness of the joint through the variable stiffness mechanism, which can not only improve the force control bandwidth in the high stiffness state, but also enhance the torque sensing sensitivity in the low stiffness state. The stiffness of the joint can be flexibly adjusted according to the actual working condition, the high-precision position control is ensured, the safety of human-machine interaction is improved, the power transmission efficiency is optimized through the synergistic effect of the driving assembly 300 and the output assembly 200, and the energy consumption of stiffness adjustment is reduced.

[0081] It should be noted that all the directional indications in the embodiments of the application, such as up, down, left, right, front, back, etc., are only used to explain the relative position relationship, motion condition, etc. between the components in a certain specific posture (as shown in the drawings), and if the specific posture changes, the directional indications also change accordingly.

[0082] In addition, the description of "first", "second", "one" and the like in the application is only for the purpose of description, and cannot be understood as indicating or implying the relative importance of the indicated technical features or implicitly indicating the number of the indicated technical features. Therefore, the features limited by "first" and "second" can be explicitly or implicitly included at least one of the features. In the description of the application, the meaning of "multiple" is at least two, such as two, three, etc., unless otherwise specifically limited.

[0083] In the present application, unless specifically defined and limited otherwise, the terms "connection", "fixing", and the like should be interpreted broadly, for example, "fixing" can be fixed connection, or detachable connection, or integral; can be mechanical connection, or electrical connection; can be directly connected, or indirectly connected through an intermediate medium; can be internal connection of two elements, or interaction relationship between two elements, unless specifically limited. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0084] In addition, the technical solutions of various embodiments of the present application can be combined with each other, but it must be based on the fact that a person skilled in the art can realize it, when the combination of technical solutions appears contradictory or unachievable, it should be considered that the combination of technical solutions does not exist, nor is it within the scope of protection required by the present application.

Claims

1. A variable stiffness mechanism, characterized by, The utility model relates to a variable stiffness mechanism of a wind turbine, comprising: a frame; an output assembly comprising a guide wheel frame, a first guide wheel, a second guide wheel and a stiffness adjusting rope, the guide wheel frame being rotatably connected to the frame, the first guide wheel and the second guide wheel being arranged on the guide wheel frame, and the stiffness adjusting rope being wound around the first guide wheel and the second guide wheel; a driving assembly comprising a first disc, a second disc and a movable piece, the first disc and the second disc being rotatably connected to the frame, the movable piece being connected to the first disc and the second disc, the movable piece and the first guide wheel being arranged along the radial direction of the first disc in sequence, and the movable piece being in abutment with the stiffness adjusting rope; when the first disc and the second disc rotate relative to each other, the movable piece moves along the radial direction of the first disc, and the movable piece drives the guide wheel frame to rotate through the stiffness adjusting rope.

2. The variable stiffness mechanism of claim 1, wherein, The first disc is provided with a straight slot extending along the radial direction, the second disc is provided with an arc-shaped slot, and the movable piece is inserted into the arc-shaped slot and the straight slot; when the first disc and the second disc rotate relative to each other, the arc-shaped slot drives the movable piece to move along the straight slot to adjust the distance between the movable piece and the first guide wheel.

3. The variable stiffness mechanism of claim 2, wherein, The movable piece comprises a shaft body, a first flange and a second flange, the first flange and the second flange being protruded from the peripheral wall of the shaft body, and the shaft body being in abutment with the slot wall of the arc-shaped slot; the first flange is arranged in a square shape, the first flange is in abutment with the slot wall of the straight slot, and the second flange is clamped between the first disc and the second disc.

4. A variable stiffness mechanism according to claim 2 or 3, wherein, The frame is rotatably connected to a mounting shaft, the guide wheel frame is fixedly arranged on the mounting shaft, the first guide wheel is provided in a plurality of pieces, and the plurality of first guide wheels are arranged at intervals in the circumferential direction of the mounting shaft; the second guide wheel is provided in a plurality of pieces, the plurality of second guide wheels are arranged at the periphery of the plurality of first guide wheels, and the stiffness adjusting rope is wound around the plurality of first guide wheels and the plurality of second guide wheels; the stiffness adjusting rope around at least one first guide wheel and two second guide wheels forms an accommodation space, and the movable piece is arranged in the accommodation space.

5. The variable stiffness mechanism of claim 4, wherein, The movable piece is provided in a plurality of pieces, the straight slot is provided in a plurality of pieces, the arc-shaped slot is provided in a plurality of pieces, and the plurality of movable pieces, the plurality of straight slots, the plurality of arc-shaped slots and the plurality of first guide wheels are arranged in one-to-one correspondence; the number of the second guide wheels is twice the number of the first guide wheels.

6. The variable stiffness mechanism of claim 1, wherein, The output assembly further comprises a fixed seat, a connecting rod, an elastic piece and a pre-tightening bolt, the connecting rod connecting the guide wheel frame and the fixed seat, the pre-tightening bolt being threadedly connected to the fixed seat, the first end of the elastic piece being connected to the fixed seat, the second end of the elastic piece being connected to the first end of the stiffness adjusting rope, and the second end of the stiffness adjusting rope being connected to the pre-tightening bolt.

7. The variable stiffness mechanism of claim 4, wherein, The variable stiffness mechanism further comprises a first encoder, the first encoder being arranged on the frame, a magnetic steel being arranged on the mounting shaft, and the first encoder measuring the relative rotation angle between the guide wheel frame and the frame through the magnetic steel.

8. The variable stiffness mechanism of claim 4, wherein, The variable stiffness mechanism further comprises a second encoder arranged on the second pulley, a first magnetic ring is sleeved on the mounting shaft, and a second magnetic ring is sleeved on the first pulley, the second encoder measures the relative rotation angle of the guide pulley frame and the first pulley or the second pulley through the first magnetic ring, and the second encoder measures the relative rotation angle of the first pulley and the second pulley through the second magnetic ring.

9. The variable stiffness mechanism of claim 1, wherein, The driving assembly further comprises a first driving machine and a second driving machine, a first driving rope is wound around the first pulley, and a second driving rope is wound around the second pulley, the first driving rope is connected with the output end of the first driving machine, and the second driving rope is connected with the output end of the second driving machine.

10. A robot, characterized in that The variable stiffness mechanism comprises the variable stiffness mechanism according to any one of claims 1-9.

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