A variable deceleration ratio-variable stiffness coupled anthropomorphic robot knee joint

Abstract

This invention discloses a humanoid robot knee joint with variable reduction ratio and variable stiffness coupling, comprising a motor module, a push rod module, a variable four-bar linkage speed ratio module, a variable stiffness elastic unit, ropes, and a base plate. The motor module provides the main driving force, the push rod module adjusts the joint stiffness and reduction ratio, and the variable four-bar linkage speed ratio module adjusts the reduction ratio curve by changing the distance between the input and output shafts of the four-bar linkage. The variable stiffness elastic unit, ropes, and the motor end pulley in the motor module and the pulley in the variable four-bar linkage speed ratio module constitute an antagonistic variable stiffness mechanism, and the stiffness of the mechanism is changed by changing the pre-tension. This invention couples the variable four-bar linkage speed ratio module and the antagonistic variable stiffness mechanism, balancing high burst power and mechanical buffering capacity, which is beneficial for the robot to perform jumping movements. In addition, the reduction ratio curve and joint stiffness can be adjusted simultaneously with a single push rod, saving the use of drive components.

Description

Technical Field

[0001] This invention belongs to the field of humanoid robot technology, specifically relating to a humanoid robot knee joint with variable deceleration ratio and variable stiffness coupling. Background Technology

[0002] The jumping motion of humanoid robots requires strong explosive power and good cushioning capacity in the robot's knee joint. To enhance the explosive power of the knee joint, a common technical solution is to design a variable reduction ratio mechanism at the robot's knee joint. This ensures that the knee joint decelerates more significantly when the robot squats and less significantly when standing up, meeting the different torque and speed requirements of the knee joint at different stages of the jump. The impact of the jump is mainly buffered by a compliant control algorithm. To improve the mechanical cushioning capacity of the knee joint, a common technical solution is to add a variable stiffness mechanism to the robot's knee joint. During takeoff, the joint is at high stiffness to improve torque response speed and the accuracy of the jump; during landing, the joint is at low stiffness, using flexible components to absorb the impact.

[0003] Variable reduction ratio joints can effectively improve the explosive power of a robot's knee joint, but due to the lack of flexible components, they are easily damaged by large impacts when the robot lands. Variable stiffness joints can adjust their own stiffness, balancing the accuracy of take-off movements and the cushioning of landing, but their maximum output torque is often less than that of rigid joints, and they are only used in small humanoid jumping robots. It is evident that the main drawback of existing humanoid robot knee joints is the difficulty in balancing high explosive power and mechanical cushioning. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a humanoid robot knee joint with variable reduction ratio and variable stiffness coupling.

[0005] The present invention achieves the above-mentioned technical objectives through the following technical means.

[0006] A humanoid robot knee joint with variable reduction ratio and variable stiffness coupling, comprising:

[0007] The motor module includes a motor, a sliding motor base, a linear bearing A, a motor end pulley, a motor end rope pressure plate, a rope pressure block A, a motor module guide rail base plate, and an optical shaft A. The linear bearing A is mounted on the bottom of the sliding motor base, and the optical shaft A is mounted on the boss of the motor module guide rail base plate. The linear bearing A is connected to the optical shaft A and can slide along the optical shaft A. The motor is mounted on one side of the sliding motor base, and the motor end pulley is located on the other side of the sliding motor base and connected to the motor. The motor end rope pressure plate is mounted on the axial surface of the motor end pulley, and the rope pressure block A is connected to the motor end rope pressure plate.

[0008] A push rod module includes a push rod, a push rod connector, and a push rod mounting base; the push rod is connected to the push rod mounting base, and the push rod connector is installed at the head of the push rod;

[0009] A variable-structure four-bar linkage gear ratio module includes an input shaft, a left input shaft seat plate, a right input shaft seat plate, an input shaft sliding seat, a linear bearing B, a push rod connecting plate, a rope pulley adapter, a connecting rod end rope pulley, a connecting rod end rope pressure plate, a rope pressure block B, an input shaft base plate, a light shaft B, an output shaft, a left output shaft seat plate, a right output shaft seat plate, an output shaft seat base plate, an input rod, a movable rod, and an output rod. The two ends of the input shaft are connected to the left and right input shaft seat plates respectively via bearings. The push rod connecting plate is connected to the inner side of the left and right input shaft seat plates, and the lower part is connected to the input shaft sliding seat. The push rod connecting plate is connected to the push rod connector. A linear bearing B is installed at the bottom of the input shaft sliding seat. An optical axis B is fixed to the base plate of the input shaft via a boss. The linear bearing B is connected to the optical axis B and can slide along the optical axis B. An input rod is fixed to one end of the input shaft, and the input rod is located on the same side as the motor. The other end of the input shaft is connected to a rope wheel adapter, which is connected to a connecting rod end rope wheel. A connecting rod end rope pressure plate is installed on the axial surface of the connecting rod end rope wheel, and a rope pressure block B is connected to the connecting rod end rope pressure plate. The two ends of the output shaft are respectively connected to the left plate and the right plate of the output shaft seat via bearings. The lower parts of the left plate and the right plate of the output shaft seat are connected to the base plate of the output shaft seat. An output rod is connected to one end of the output shaft. The output rod, the movable rod, and the input rod are stacked and connected in sequence to form a connecting rod structure.

[0010] The variable stiffness elastic unit includes a through-hole housing, a bottom housing, a rope connecting cover, a mandrel, a low-stiffness spring, a high-stiffness spring, disc springs, and a limiting sleeve. Both the through-hole housing and the bottom housing are U-shaped frame structures with an axially circular shape. The internal space formed by their staggered fit is used to house the spring assembly. Rope connecting covers are installed at the open ends of both housings. The mandrel passes through the through-hole at the bottom of the through-hole housing. One end of the mandrel is installed in a circular groove at the bottom of the bottom housing, and the other end is installed in a circular groove on the lower surface of the rope connecting cover at the open end of the bottom housing. The spring assembly is arranged on the mandrel in the following order: low-stiffness spring - limiting sleeve - high-stiffness spring - limiting sleeve - multiple disc springs.

[0011] Both the motor end pulley and the connecting rod end pulley have two grooves around their circumferences. Two sets of through holes are provided in the grooves along the diameter direction. Each set has two through holes, which serve as rope holes. The two sets of rope holes are arranged symmetrically around the axis of the pulley. The two rope holes on the same side are respectively inserted into the two ends of a rope. The rope ends are wrapped around the rope pressure block A / rope pressure block B.

[0012] The connecting rod end pulley, the motor end pulley, the rope, and the variable stiffness elastic unit together form an antagonistic variable stiffness mechanism. The antagonistic variable stiffness mechanism is based on the pulley-rope transmission mechanism, with the motor end pulley as the input end and the connecting rod end pulley as the output end. The two variable stiffness elastic units are respectively installed on the middle of the rope on the upper and lower sides of the pulley, and the rope is connected to the rope connection cover.

[0013] In the above technical solution, the motor module further includes an adjusting screw and an adjusting nut. The tail of the adjusting screw passes through the bottom of the sliding motor seat and the boss on the bottom plate of the motor module guide rail, and is connected to the adjusting nut. The adjusting nut is in contact with the boss on the bottom plate of the motor module guide rail.

[0014] In the above technical solution, the connection between the output rod, the movable rod, and the input rod is accomplished through a connecting rod shaft, a copper washer, a copper baffle, and a needle roller bearing.

[0015] In the above technical solution, a needle roller bearing is pressed into each end of the movable rod, and a connecting rod shaft, copper washer, and copper baffle are installed at corresponding positions on the input rod and output rod. The copper washer and copper baffle clamp the needle roller bearing, and the input rod, movable rod, and output rod are connected in sequence through the connecting rod shaft and needle roller bearing.

[0016] In the above technical solution, the output rod is axially positioned by an output shaft baffle at one end of the output shaft.

[0017] In the above technical solution, the upper part of the left plate and the right plate of the input shaft seat is connected to the input shaft seat cover plate.

[0018] The above technical solution also includes a base plate, on which the motor module guide rail base plate, push rod fixing seat, input shaft base plate, and output shaft seat base plate are all mounted.

[0019] In the above technical solution, the height of the push rod is consistent with the center height of the motor end pulley and the connecting rod end pulley.

[0020] In the above technical solution, the diameter of the output shaft is smaller than that of the input shaft.

[0021] In the above technical solution, the variable structure four-bar linkage speed ratio module also includes an encoder, which is installed on the outside of the left plate of the output shaft seat and connected to the other end of the output shaft.

[0022] The beneficial effects of this invention are as follows:

[0023] (1) This invention designs a humanoid robot knee joint with variable reduction ratio and variable stiffness coupling, combining a variable four-bar linkage speed ratio module and an antagonistic variable stiffness mechanism. In the specific design, the main body of the variable four-bar linkage speed ratio module is a variable four-bar structure, and the position of its input shaft can be changed along the sliding track, so that the speed ratio module changes between the parallel four-bar mechanism and the double crank mechanism, thereby realizing the adjustment of the reduction ratio curve. The antagonistic variable stiffness mechanism consists of a rope wheel-rope transmission structure and a tension-type variable stiffness elastic unit. The variable stiffness elastic unit is connected in series on the ropes on both sides of the rope wheel to form an antagonistic arrangement. The stiffness is adjusted by changing the distance between the input and output rope wheels. This invention amplifies the output torque of the antagonistic variable stiffness mechanism through the variable four-bar linkage speed ratio module, and uses the variable stiffness elastic unit to provide mechanical buffer for the joint to cope with the impact of the robot's landing, taking into account both high explosive power and mechanical buffering capacity.

[0024] (2) In the specific design of this invention, the input shaft of the variable structure four-bar linkage speed ratio module is connected to the connecting rod end rope wheel of the antagonistic variable stiffness mechanism, which couples the adjustment of the reduction ratio and stiffness together. The distance between the input and output shafts and the distance between the rope wheels can be changed by a push rod, and the joint reduction ratio change curve and joint stiffness can be actively adjusted at the same time, saving the use of drive components.

[0025] (3) In this invention, the adjustment and coupling of the variable structure four-bar speed ratio module and the antagonistic variable stiffness mechanism realizes the coupling of two modes: large stiffness and large reduction ratio of the joint and small stiffness and small reduction ratio. The large stiffness and large reduction ratio mode meets the requirements of the robot for joint explosive force and motion accuracy when jumping. The small stiffness and small reduction ratio mode is more suitable for absorbing impact, which helps to prevent the robot from damaging the hardware when landing. In principle, it is beneficial for the robot to perform jumping motion. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the humanoid robot knee joint device with variable reduction ratio and variable stiffness coupling as described in this invention.

[0027] Figure 2 This is a schematic diagram of the motor module structure described in this invention;

[0028] Figure 3 This is an exploded view of the motor module described in this invention;

[0029] Figure 4 This is a bottom cross-sectional view of the motor module described in this invention;

[0030] Figure 5 This is a schematic diagram of the push rod module structure described in this invention;

[0031] Figure 6 This is the right-side axonometric view of the variable four-bar linkage gear ratio module described in this invention;

[0032] Figure 7 This is the left axonometric view of the variable four-bar linkage gear ratio module described in this invention;

[0033] Figure 8 This is a three-dimensional cross-sectional view of the sliding track structure in the variable four-bar linkage speed ratio module of the present invention;

[0034] Figure 9(a) is a structural diagram of the variable stiffness elastic unit described in this invention;

[0035] Figure 9(b) is a cross-sectional view of the variable stiffness elastic unit described in this invention;

[0036] Figure 10 This is a schematic diagram of the rope connection of the variable stiffness elastic unit described in this invention;

[0037] Figure 11 This is a structural diagram of the antagonistic variable stiffness mechanism described in this invention;

[0038] Figure 12 This is a schematic diagram of the installation of a single rope on a rope pulley according to the present invention;

[0039] In the diagram: 1-Motor module, 2-Push rod module, 3-Variable structure four-bar linkage speed ratio module, 4-Variable stiffness elastic unit, 5-Rope, 6-Base plate, 101-Motor, 102-Sliding motor seat, 103-Linear bearing A, 104-Motor end rope pulley, 105-Motor end rope pressure plate, 106-Rope pressure block A, 107-Motor module guide rail base plate, 108-Optical shaft A, 109-Adjusting screw, 110-Adjusting nut, 201-Push rod, 202-Push rod connector, 203-Push rod fixing seat, 301-Input shaft, 302-Input shaft seat left plate, 303-Input shaft seat right plate, 304-Input shaft sliding seat, 305-Input shaft seat cover plate, 306-Linear bearing B, 307-61807 bearing, 308-Push rod connecting plate, 30 9-Rope pulley adapter, 310-Connecting rod end rope pulley, 311-Connecting rod end rope pressure plate, 312-Rope pressure block B, 313-Input shaft base plate, 314-Optical shaft B, 315-Output shaft, 316-Output shaft seat left plate, 317-Output shaft seat right plate, 318-Output shaft seat base plate, 319-16002 bearing, 320-Encoder, 321-Output shaft baffle, 322-Input rod, 323-Moving rod, 324-Output rod, 325-Connecting rod shaft, 326-Copper washer, 327-Copper baffle, 401-Through hole housing, 402-Sealed bottom housing, 403-Rope connecting cover, 404-Mandrel, 405-Low stiffness spring, 406-High stiffness spring, 407-Disc spring, 408-Limit sleeve, 409-Plug screw, 410-Nut. Detailed Implementation

[0040] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, but the scope of protection of the present invention is not limited thereto.

[0041] This invention relates to a humanoid robot knee joint that integrates a variable-structure four-bar linkage speed ratio module and an antagonistic variable stiffness mechanism. It achieves a balance between high explosive power and mechanical cushioning, while also realizing the coupled active adjustment of joint reduction ratio and joint stiffness. Its basic structure consists of a motor module 1, a pushrod module 2, a variable-structure four-bar linkage speed ratio module 3, a variable stiffness elastic unit 4, a rope 5, and a base plate 6. Figure 1 As shown.

[0042] Motor module 1 is the main driving part of the knee joint of this humanoid robot. It mainly consists of motor 101, sliding motor base 102, linear bearing A103, motor end pulley 104, motor end rope pressure plate 105, rope pressure block A106, motor module guide rail base plate 107, optical shaft A108, adjusting screw 109, and adjusting nut 110. Figure 2 , 3As shown in Figure 4, the sliding motor base 102 is mainly used to connect the motor 101 and the sliding rail A. Its structure is L-shaped, with the sidewalls for mounting the motor 101 and triangular ribs between the sidewalls and the bottom to enhance structural stability under stress. The bottom of the sliding motor base 102 has two pairs of linear bearing mounting holes, with set screw holes on the sides of the mounting holes for mounting and fixing linear bearings A103. The screw through-holes and pin holes on the axial surface of the motor end pulley 104 are used to connect the motor 101. The motor end pulley 104 has two grooves on its circumference, each groove's width being equivalent to two ropes 5, to prevent the ropes 5 from slipping off the motor end pulley 104. In the grooves, two sets of through holes (two holes in each set) are provided along the diameter direction as rope holes. The two sets of rope holes are arranged symmetrically around the pulley axis for threading the ropes 5. The axial surface of the motor end pulley 104 near the rope holes is hollowed out to avoid affecting the installation of the ropes 5. The motor end rope pressure plate 105 is mounted on the axial surface of the motor end rope pulley 104 by countersunk screws, and four rope pressure blocks A106 are connected to it by screws to fix the rope 5. The boss of the motor module guide rail base plate 107 is provided with a pair of optical shaft mounting holes. Two optical shafts A108 are respectively passed through the two sets of mounting holes and are fixed by set screws to form a sliding track A. The sliding motor seat 102 is connected to the optical shaft A108 through the linear bearing A103 and can slide along the optical shaft A108. Its sliding range is limited by the boss on the motor module guide rail base plate 107. The boss on the motor module guide rail base plate 107 and the bottom of the sliding motor seat 102 are both provided with adjusting screw mounting holes. These holes are slightly larger than the outer diameter of the adjusting screw 109. The adjusting screw 109 passes through both holes, with its head located inside the bottom of the sliding motor seat 102 and its tail extending outwards from the outside of the motor module guide rail base plate 107 to connect with the adjusting nut 110. The adjusting nut 110 needs to be tightened until it contacts the boss on the motor module guide rail base plate 107. The specific situation after installation is as follows: Figure 4 As shown. By rotating the adjusting nut 110, the adjusting screw 109 can drive the sliding motor base 102 to slide on the motor module guide rail base plate 107. This design is used for pre-tensioning after the rope 5 is installed.

[0043] The push rod module 2 is used to adjust the position of the input shaft 310 of the variable linkage four-bar linkage speed ratio module, thereby changing the output stiffness and reduction ratio of the joint. It consists of a push rod 201, a push rod connector 202, and a push rod mounting base 203. Figure 5As shown. The push rod 201 uses a trapezoidal screw drive to ensure its self-locking capability. One end of the push rod connector 202 is installed at the head of the push rod 201, and the other end is connected to the push rod connecting plate 308 of the variable four-bar linkage speed ratio module 3, which drives the input shaft 301 of the variable four-bar linkage speed ratio module 3 to adjust its position with the movement of the push rod 201. The upper part of the push rod fixing seat 203 is used to connect the push rod 201, and it is necessary to ensure that the height of the push rod 201 in the humanoid robot's knee joint is consistent with the center height of the two rope pulleys (motor end rope pulley 104 and connecting rod end rope pulley 310); the bottom of the push rod fixing seat 203 is provided with pin holes and screw through holes for connecting the push rod module 2 and the base plate 6.

[0044] The variable-structure four-bar linkage speed ratio module 3 mainly adjusts the distance between the input shaft 301 and the output shaft 315 by moving the input shaft 301 along the sliding track B, thereby changing the configuration of the four-bar linkage and thus changing the reduction ratio curve. It consists of the input shaft 301, the left plate of the input shaft seat 302, the right plate of the input shaft seat 303, the input shaft sliding seat 304, the input shaft seat cover plate 305, the linear bearing B 306, the 61807 bearing 307, the push rod connecting plate 308, and the rope pulley adapter. Composed of 309, 310, 311, 312, 313, 314, 315, 316, 317, 318, 319, 320, 321, 322, 323, 324, 325, 326, 327, 326, 327, 328, 329, 320, 321, 322, 323, 324, 325, 326, 327 ...2, 323, 324, 325, 326, 327, 32 Figure 6 and Figure 7 As shown.

[0045] The input shaft 301 is connected to the left plate 302 and the right plate 303 of the input shaft seat via 61807 bearings 307 at both ends. The upper parts of the left and right plates are connected to the input shaft seat cover plate 305 via cylindrical pins and screws to enhance structural stability. A push rod connecting plate 308 is connected to the inner side of the left and right plates, and is used to connect to the push rod connector 202. The lower parts of the left and right plates are connected to the input shaft sliding seat 304. Two sets of linear bearings B306 are installed in pairs at the bottom of the input shaft sliding seat 304, forming a slider structure. Two parallel optical shafts B314 are fixed to the input shaft base plate 313 via a boss, forming a sliding track B. The boss acts as a limit. The input shaft sliding seat 304 is connected to the optical shafts B314 via linear bearings B306 (e.g., ...). Figure 8As shown, the input shaft 301 can slide along the optical axis B314 to change the distance from the output shaft 315, thus realizing a four-bar linkage configuration. The input shaft 301 has pin holes and keyways at both ends. The pin holes are used for positioning and fixing the input rod 322, and the keyways are used to connect the rope pulley adapter 309, which in turn connects to the connecting rod end rope pulley 310. The structure of the connecting rod end rope pulley 310 is similar to that of the motor end rope pulley 104, also having a groove for mounting the rope 5 and radial rope holes. A connecting rod end rope pressure plate 311 is mounted on the axial surface of the connecting rod end rope pulley 310, and four rope pressure blocks B312 are connected to the surface of the pressure plate by screws to fix the rope 5.

[0046] The output shaft 315 is connected to the left plate 316 and the right plate 317 of the output shaft seat via 16002 bearings 319 at both ends. The lower part of the left and right plates of the output shaft seat is connected to the bottom plate 318 of the output shaft seat. The outer side of the left plate 316 of the output shaft seat has a circular boss for mounting the encoder 320. The output shaft 315 transmits a smaller torque and has a smaller diameter than the input shaft 301. It mainly serves to support the output rod 324 and transmit rotational motion to the encoder 320. The output shaft 315 is connected to the rotating part of the encoder 320 through the cylindrical boss at the shaft end, enabling the encoder 320 to measure the angle of the joint output end. This can effectively offset the interference of the clearance at the linkage connection and the spring stiffness error on the position control, and improve the joint position control accuracy. The square boss at the other end of the output shaft 315 is used to connect the output rod 324, and the axial positioning of the output rod 324 is achieved by the output shaft baffle 321 at the top. The output rod 324 is an integrated part that combines a connecting rod and an output flange. The annular part has threaded holes and pin holes, which can be used directly as the output end of the joint, or connected to a force sensor or other flange components.

[0047] Input rod 322, movable rod 323, and output rod 324 are stacked and connected in sequence to form a three-layer linkage structure, which expands the range of rotational motion while achieving speed change function. The connection between the three linkages is completed through linkage shaft 325, copper washer 326, copper baffle 327, and needle roller bearing (not shown in the figure). Linkage shaft 325 is made of high-strength titanium alloy to resist the bending moment generated at the connection during linkage transmission and improve the mechanism's load-bearing capacity. The needle roller bearing without inner ring is installed on movable rod 323, with the needle rollers directly contacting linkage shaft 325, achieving miniaturization of the linkage connection. The needle roller bearing is clamped on both sides by copper washer 326 and copper baffle 327 to achieve axial positioning, while the self-lubricating properties of copper reduce linkage transmission friction.

[0048] The variable stiffness elastic unit 4 consists of a through-hole housing 401, a bottom-sealed housing 402, a rope connecting cover 403, a spindle 404, a low-stiffness spring 405, a high-stiffness spring 406, a disc spring 407, a limiting sleeve 408, a stop screw 409, and a nut 410, as shown in Figures 9(a) and (b). The through-hole housing 401 and the bottom-sealed housing 402 have similar structures, both being U-shaped frame structures with a circular axial direction. The top (open end) of the U-shaped frame has a threaded hole for fixing the rope connecting cover 403. The bottom of the through-hole housing 401 has a through hole with a diameter slightly larger than that of the spindle 404, facilitating sliding on the spindle 404. The bottom of the bottom-sealed housing 402 has a circular groove, which, together with the circular groove on the lower surface of the rope connecting cover 403, fixes the spindle 404. In the variable stiffness elastic unit 4, the through-hole shell 401 and the bottom shell 402 are staggered together. The contact surfaces need to be polished smooth so that the shells can slide smoothly relative to each other. The internal space formed by the two shells is used to place the spring assembly.

[0049] The spring assembly is fitted onto the mandrel 404 in the following order: low-stiffness spring 405 - limiting sleeve 408 - high-stiffness spring 406 - limiting sleeve 408 - multiple disc springs 407. The low-stiffness spring 405, high-stiffness spring 406, and disc springs 407 are all located inside the sleeve structure of the limiting sleeve 408 (see Figure 9(b)). All of these components can slide along the mandrel 404. When the variable-stiffness elastic unit 4 is subjected to axial tension, the internal space formed by the interlocking of the two shells shrinks, causing the spring to compress and generate elastic force. The stiffness of the variable-stiffness elastic unit 4 is determined by the series stiffness of the spring assembly. The limiting sleeve 408 is a cylindrical sleeve structure with a partition, used to limit the maximum compression of the spring. When the limiting sleeve 408 contacts the shell or the limiting sleeve 408 itself, the spring inside the limiting sleeve 408 will no longer be further compressed, effectively failing. By using sleeves of different lengths, the corresponding failure compression amount of the spring can be set. During the stretching process of the variable stiffness elastic unit 4, the springs in the spring group will fail in sequence according to the order of stiffness from low to high, so that the stiffness of the variable stiffness elastic unit increases in a step-like manner, thus realizing the function of stretching and changing stiffness.

[0050] The rope connecting cover 403 has two upright plates with screw through holes for connecting the rope 5. In this invention, both ends of each rope 5 are fixed to the rope pulley to form a rope loop. The rope loop is placed between the upright plates of the rope connecting cover 403, close to the rope connecting cover 403. The plug screw 409 is inserted into the through hole on the upright plate and fixed with the nut 410, so that the rope 5 can be clamped on the rope connecting cover 403, as shown in Figure 9(a) and 9(b). Figure 10 As shown.

[0051] The connecting rod end pulley 310 of the variable-structure four-bar linkage gear ratio module 3, the motor end pulley 104 of the motor module 1, the rope 5, and the variable stiffness elastic unit 4 together form an antagonistic variable stiffness mechanism, the structure of which is as follows: Figure 11As shown, this antagonistic variable stiffness mechanism is based on a pulley-rope transmission mechanism, with the motor-end pulley 104 as the input and the connecting rod-end pulley 310 as the output. Two variable stiffness elastic units 4 are respectively installed in the middle of the ropes 5 on both sides of the pulleys, moving together with the ropes 5 to form an antagonistic arrangement simulating biological joint muscles. In the antagonistic variable stiffness mechanism, the pulley-rope transmission structure converts the tensile stiffness of the variable stiffness elastic unit 4 into the rotational stiffness of the output end (i.e., the connecting rod-end pulley 310). By changing the distance between the two pulleys, the rotational stiffness of the mechanism can be adjusted. When the distance between the two pulleys increases, the tensile stiffness of the two variable stiffness elastic units 4 increases in a stepwise manner, and the rotational stiffness of the output pulley of the antagonistic variable stiffness mechanism also increases accordingly, ultimately increasing the joint stiffness.

[0052] The installation method and connection relationship of the variable reduction ratio-variable stiffness coupled humanoid robot knee joint of the present invention are as follows: the variable reduction ratio-variable stiffness coupled humanoid robot knee joint adopts a modular installation method during installation, each component module is assembled separately, and finally the modules are connected.

[0053] During motor module 1 installation, first install motor 101 and linear bearing A103 into their corresponding positions on the sliding motor base 102 and secure them with screws and set screws. Align the inner ring of linear bearing A103 with the optical shaft mounting holes on the boss of motor module guide rail base plate 107, then insert two optical shafts A108 and secure them with set screws, connecting the sliding motor base 102 to the motor module guide rail base plate 107. Insert adjusting screw 109 into the adjusting screw mounting hole from the bottom opening of the sliding motor base 102, with the screw head located inside the bottom of the sliding motor base 102 and the screw tail extending outside the motor module guide rail base plate 107, connecting it to adjusting nut 110. The nut needs to be tightened until it contacts the boss of the motor module guide rail base plate 107. Adjust all parts to ensure that the position of the adjusting screw and the position of the sliding motor base 102 are as described above. Figure 4 As shown.

[0054] Next, two ropes 5 are threaded onto the motor end pulley 104. Specifically, the two ends of one rope 5 are threaded into the two radial rope holes on one side of the motor end pulley 104, and the two ends of the other rope 5 are threaded into the two radial rope holes on the opposite side. The motor end pulley 104 is then installed onto the output shaft of the motor 101 and secured with screws. Finally, the motor end rope pressure plate 105 is fixed to the surface of the motor end pulley 104 with countersunk screws. Next, secure the rope ends. Wrap the rope 5, which is passing through the rope hole, twice around the rope pressure block A106, with the wrapping position between the two screw holes of the rope pressure block A106. Then, secure the rope pressure block A106 to the motor-end rope pressure plate 105 using two screws. Tighten the screws firmly to ensure the rope pressure block A106 presses the rope 5 tightly against the motor-end rope pressure plate 105, ensuring reliable fixation. Secure all four rope ends in this manner. Then, coil the secured rope 5 half a turn around the motor-end rope pulley 104, taking care to avoid tangling or overlapping between the ropes 5. After installation, a single rope 5 should... Figure 12 As shown in the figure, the black and gray lines represent the fixed positions of the two ends of a rope 5, respectively, and the dashed line represents the coiling of the rope 5 on the rope wheel. The length of the rope 5 needs to be determined in advance based on the diameter and spacing of the two rope wheels in the humanoid robot's knee joint, the length of the variable stiffness elastic unit, and the fixed length of the rope. The rope 5 is cut to the required length during installation.

[0055] When installing the push rod module 2, install the push rod 201 on the push rod fixing seat 203 and tighten it with screws. Install the push rod connector 202 on the head of the push rod 201 and rotate the head of the push rod 201 to its minimum extension length to complete the installation of the push rod module 2.

[0056] During the installation of the variable-structure four-bar linkage gear ratio module 3, the input shaft 301 is first connected to the left plate 302 and right plate 303 of the input shaft seat via the 61807 bearing 307. Then, the input shaft seat cover plate 305, push rod connecting plate 308, and input shaft sliding seat 304 are installed at corresponding positions on the left and right plates and secured with screws and pins. The linear bearing B306 is installed on the input shaft sliding seat 304 and secured with set screws. The inner ring of the linear bearing B306 is aligned with the optical shaft mounting holes on the boss of the input shaft base plate 313. Two optical shafts B314 are inserted and secured with set screws, thus connecting the input shaft sliding seat 304 to the input shaft base plate 313. The keyway end of the input shaft 301 is connected to the rope pulley adapter 309 via a flat key. The pin hole end of the input shaft 301 is fitted onto the input rod 322. The angle of the input rod 322 is adjusted to align the pin hole and insert a cylindrical pin. The connecting rod end pulley 310 is connected to the pulley adapter 309 via screws and cylindrical pins. A connecting rod end rope pressure plate 311 and rope pressure block B312 are mounted on it. The installation and fixing method of the rope 5 is the same as the rope installation process for the motor end pulley 104. Next, the output shaft 315 is connected to the left plate 316 and right plate 317 of the output shaft seat via a 16002 bearing 319. An output shaft seat base plate 318 is installed on the lower part of both plates and secured with screws. The output rod 324 is pressed into the end of the output shaft 315 with a square boss and axially fixed by the output shaft baffle 321. An encoder 320 is mounted on the left plate 316 of the output shaft seat. The rotating part of the encoder 320 is connected to the output shaft 315 via set screws. A needle roller bearing is pressed into each end of the movable rod 323. A connecting rod shaft 325 and a copper washer 326 are installed at corresponding positions on the input rod 322 and output rod 324. The input rod 322, movable rod 323, and output rod 324 are connected sequentially via the connecting rod shaft 325 and the needle roller bearings, and axially fixed using a copper baffle 327. The effect after installation is as follows. Figure 6 As shown. The assembly of the variable four-bar linkage gear ratio module 3 is now complete.

[0057] When assembling the variable stiffness elastic unit 4, first place the bottom housing 402 with the opening facing upwards, insert the mandrel 404 into the bottom circular groove of the bottom housing 402, and then sequentially fit multiple disc springs 407, limit sleeves 408, high stiffness springs 406, limit sleeves 408, and low stiffness springs 405 onto the mandrel 404. Then, fasten the through-hole housing 401 and press it down appropriately so that the mandrel 404 protrudes through the bottom through-hole of the through-hole housing 401. Install the rope connection cover 403 on the open end of the bottom housing 402, so that the circular groove on its lower surface is inserted into the mandrel 404 and secured with screws. Then, install the rope connection cover 403 on the open end of the through-hole housing 401 and secure it with screws. The plug screws 409 and nuts 410 will be installed during module connection.

[0058] After the assembly of each module is completed, each module is installed on the corresponding position on the base plate 6 and fastened with screws and cylindrical pins. Specifically, the motor module 1 is installed on the base plate 6 through the motor module guide rail base plate 107, the push rod module 2 is installed on the base plate 6 through the push rod fixing seat 203, and the variable structure four-bar linkage speed ratio module 3 is installed on the base plate 6 through the input shaft base plate 313 and the output shaft seat base plate 318. Connect the push rod connector 202 of push rod module 2 to the push rod connecting plate 308 of variable four-bar linkage speed ratio module 3 with screws. Adjust the length of push rod 201 to make the four-bar linkage mechanism in a parallel four-bar configuration. Then connect the two variable stiffness elastic units 4 to the ropes 5 on both sides of the rope wheel with plug screws 409 and nuts 410 respectively. Refer to Figure 9 for the connection method. During this process, the rope length of the rope wheel-rope transmission part can be adjusted by changing the length of the rope 5 passing through the rope wheel to prevent the rope 5 from being too loose. Finally, turn the adjusting nut 110 of motor module 1 to change the motor position and pre-tighten the rope wheel-rope transmission structure. The assembly of the humanoid robot knee joint with variable reduction ratio and variable stiffness coupling is completed. The assembled product is shown in Figure 9. Figure 1 As shown.

[0059] The working principle of the variable reduction ratio-variable stiffness coupled humanoid robot knee joint of the present invention is as follows: The main functions of the variable reduction ratio-variable stiffness coupled humanoid robot knee joint include outputting rotational motion, active stiffness variation, and active reduction ratio variation.

[0060] In the knee joint of this humanoid robot, the rotational motion at the motor end is transmitted to the input shaft 301 of the variable four-bar linkage speed ratio module 3 through the pulley-rope transmission mechanism, and then the rotational motion is transmitted to the output rod 324 through the four-bar linkage mechanism. The flange integrated with the output rod 324 outputs the rotational motion to the outside.

[0061] The active variable stiffness function of the humanoid robot's knee joint is mainly achieved by the synchronous stretching of two variable stiffness elastic elements 4. The distance between the motor-end pulley 104 and the connecting rod-end pulley 310 can be adjusted by the push rod 201. When the distance between the two pulleys increases, the variable stiffness elastic element 4 will be subjected to axial stretching. The internal space formed by the interlocking of the two shells will shrink, causing the spring group to compress. The smaller the stiffness of the spring, the greater the compression. When the spring length is less than the sleeve length of the corresponding limiting sleeve 408, the spring fails. The stiffness exhibited by the variable stiffness elastic element 4 is the series stiffness of the active springs. The active spring with the smallest stiffness plays a dominant role. During the stretching process, the springs in the spring group will fail in sequence from low to high stiffness, so that the stiffness of the variable stiffness elastic element 4 increases in a stepwise manner. Since the variable stiffness elastic element 4 is symmetrically installed on both sides of the pulley, the change in the tensile stiffness of the variable stiffness elastic element 4 will be converted into the change in the rotational stiffness of the output pulley through the pulley-rope transmission structure, thereby realizing the variable stiffness function of the humanoid robot's knee joint. The specific change process is as follows: As the stretching length increases, the limiting sleeve 408 of the low-stiffness spring 405 will contact the shell first. At this time, the low-stiffness spring 405 fails, and the high-stiffness spring 406 takes the lead, increasing the stiffness of the humanoid robot's knee joint. With further stretching, the two limiting sleeves 408 will contact each other, at which point the high-stiffness spring 406 will also fail. The stiffness of the variable-stiffness elastic element 4 is determined by the disc spring 407, further increasing the stiffness of the humanoid robot's knee joint. When the variable-stiffness elastic element 4 is stretched to its limit position, all springs fail, the limiting sleeves 408 are in complete contact with the shell, and the stiffness of the humanoid robot's knee joint reaches its maximum. Since the two variable-stiffness elastic elements 4 are symmetrically distributed on both sides of the rope wheel, when adjusting the rope wheel spacing, the two will stretch and contract synchronously, and the resulting elastic forces will cancel each other out, ensuring that the stiffness adjustment process will not generate interfering torque at the input shaft 301 of the variable-structure four-bar linkage speed ratio module 3.

[0062] The active variable reduction ratio function of the knee joint of this humanoid robot is mainly achieved by adjusting the position of the input shaft 301 of the variable four-bar linkage reduction ratio module 3 on the sliding track B using push rod 201. The input shaft 301 of the variable four-bar linkage reduction ratio module 3 in the knee joint of this humanoid robot can slide along the optical axis B314 on the input shaft base plate 313. Its position is controlled by push rod 201. When push rod 201 moves the input shaft 301, it changes the distance between the input shaft 301 and the output shaft 315, thus changing the configuration of the four-bar linkage and consequently altering the reduction ratio of the joint. When push rod 201 retracts to its limit, the four-bar linkage is a parallel four-bar linkage with a reduction ratio of 1. As push rod 201 extends, the four-bar linkage becomes a double-crank mechanism, producing a gear ratio change effect. Its reduction ratio changes with the angle of input shaft 301. The angle range with a reduction ratio greater than 1 is taken as the working range of the joint. The greater the extension of push rod 201, the smaller the distance between the two shafts, the larger the gear ratio range, and the larger the peak reduction ratio.

[0063] Because the connecting rod end pulley 310 and the input shaft 301 of the variable four-bar linkage speed ratio module 3 are connected via pulley adapter 309 in this invention, when the push rod 201 adjusts the position of the input shaft 301, the distance between the two pulleys and the distance between the input and output shafts of the variable four-bar linkage speed ratio module 3 will change simultaneously. Therefore, the adjustment of joint stiffness and joint reduction ratio in this invention is coupled. When the push rod 201 is pushed out, the pulley distance increases, the joint stiffness increases, the distance between the input and output shafts decreases, and the joint reduction ratio increases; conversely, when the push rod 201 is retracted, the joint stiffness decreases, and the reduction ratio also decreases; thus, the coupling of large joint stiffness and large reduction ratio, and small stiffness and small reduction ratio is achieved. The large stiffness and large reduction ratio mode meets the requirements of joint explosive force and motion accuracy when the robot jumps, while the small stiffness and small reduction ratio mode is more suitable for absorbing impact and helps prevent hardware damage when the robot lands. It is evident that the principle of this invention is beneficial for robots to perform jumping motions. At the same time, the coupling of variable stiffness and variable deceleration ratio reduces the number of drive components, enabling the invention to achieve active adjustment of both joint stiffness and deceleration ratio using only one push rod.

[0064] The embodiments described above are preferred embodiments of the present invention, but the present invention is not limited to the above embodiments. Any obvious improvements, substitutions or modifications that can be made by those skilled in the art without departing from the essence of the present invention shall fall within the protection scope of the present invention.

Claims

1. A variable-reduction-ratio and variable-stiffness coupled anthropomorphic robot knee joint, characterized by, include: The motor module (1) includes a motor (101), a sliding motor base (102), a linear bearing A (103), a motor end pulley (104), a motor end rope pressure plate (105), a rope pressure block A (106), a motor module guide rail base plate (107), and an optical shaft A (108); the sliding motor base (102) is equipped with a linear bearing A (103), and the optical shaft A (108) is installed on the boss of the motor module guide rail base plate (107). A linear bearing A (103) is connected to an optical axis A (108) and can slide along the optical axis A (108); a motor (101) is installed on one side of the sliding motor base (102), and a motor end pulley (104) is located on the other side of the sliding motor base (102) and connected to the motor (101); a motor end rope pressure plate (105) is installed on the axial surface of the motor end pulley (104), and a rope pressure block A (106) is connected to the motor end rope pressure plate (105); The push rod module (2) includes a push rod (201), a push rod connector (202), and a push rod mounting base (203); the push rod (201) is connected to the push rod mounting base (203), and the push rod connector (202) is installed on the head of the push rod (201); The variable-structure four-bar linkage gear ratio module (3) includes an input shaft (301), a left plate of the input shaft seat (302), a right plate of the input shaft seat (303), an input shaft sliding seat (304), a linear bearing B (306), a push rod connecting plate (308), a rope pulley adapter (309), a connecting rod end rope pulley (310), a connecting rod end rope pressure plate (311), a rope pressure block B (312), an input shaft base plate (313), an optical shaft B (314), an output shaft (315), a left plate of the output shaft seat (316), a right plate of the output shaft seat (317), and an output shaft seat. The base plate (318), input rod (322), movable rod (323), and output rod (324) are respectively connected to the left plate (302) and right plate (303) of the input shaft (301) via bearings. The inner sides of the left plate (302) and right plate (303) of the input shaft are connected to a push rod connecting plate (308), and the lower part is connected to an input shaft sliding seat (304). The push rod connecting plate (308) is connected to a push rod connector (202). A linear bearing B is installed at the bottom of the input shaft sliding seat (304). 306), the optical axis B (314) is fixed on the input shaft base plate (313) by a boss, the linear bearing B (306) is connected to the optical axis B (314) and can slide along the optical axis B (314); one end of the input shaft (301) is fixed to the input rod (322), and the input rod (322) and the motor (101) are located on the same side, the other end of the input shaft (301) is connected to the rope wheel adapter (309), and the rope wheel adapter (309) is connected to the connecting rod end rope wheel (310); the connecting rod end rope wheel (310) is mounted on the axial surface of the connecting rod end rope wheel (310). A rope pressure plate (311) is attached to the rod end rope pressure plate (311), and a rope pressure block B (312) is connected to it. The two ends of the output shaft (315) are respectively connected to the left plate (316) and the right plate (317) of the output shaft seat through bearings. The lower part of the left plate (316) and the right plate (317) of the output shaft seat is connected to the bottom plate (318) of the output shaft seat. One end of the output shaft (315) is connected to the output rod (324). The output rod (324), the movable rod (323), and the input rod (322) are stacked and connected in sequence to form a connecting rod structure. The variable stiffness elastic unit (4) includes a through-hole housing (401), a bottom-sealed housing (402), a rope connecting cover (403), a spindle (404), a low-stiffness spring (405), a high-stiffness spring (406), a disc spring (407), and a limiting sleeve (408); the through-hole housing (401) and the bottom-sealed housing (402) are both U-shaped frame structures with a circular axial direction. The internal space formed by their staggered fit together is used to place the spring assembly. The rope connecting cover (405) is installed at the open end of each of them. 03); The mandrel (404) passes through the through hole at the bottom of the through-hole housing (401). One end of the mandrel (404) is installed in the bottom groove of the bottom sealing housing (402), and the other end is installed in the lower surface groove of the rope connecting cover (403) at the open end of the bottom sealing housing (402); The spring assembly is sleeved on the mandrel (404) in the following order: low stiffness spring (405) - limiting sleeve (408) - high stiffness spring (406) - limiting sleeve (408) - multiple disc springs (407); The motor end pulley (104) and the connecting rod end pulley (310) are both provided with two grooves around their circumferences. Two sets of through holes are provided in the grooves along the diameter direction. Each set has two through holes, which serve as rope holes. The two sets of rope holes are arranged symmetrically around the axis of the pulley. The two rope holes on the same side are respectively inserted into the two ends of a rope (5). The rope ends are wrapped around the rope pressing block A (106) / rope pressing block B (312). The connecting rod end pulley (310), the motor end pulley (104), the rope (5), and the variable stiffness elastic unit (4) together form an antagonistic variable stiffness mechanism. The antagonistic variable stiffness mechanism is based on the pulley-rope transmission mechanism, with the motor end pulley (104) as the input end and the connecting rod end pulley (310) as the output end. The two variable stiffness elastic units (4) are respectively installed in the middle of the rope (5) on the upper and lower sides of the pulley, and the rope (5) is connected to the rope connection cover (403).

2. The humanoid robot knee joint with variable reduction ratio and variable stiffness coupling according to claim 1, characterized in that, The motor module (1) also includes an adjusting screw (109) and an adjusting nut (110). The tail of the adjusting screw (109) passes through the bottom of the sliding motor seat (102) and the boss on the motor module guide rail base plate (107) and is connected to the adjusting nut (110). The adjusting nut (110) contacts the boss on the motor module guide rail base plate (107).

3. The humanoid robot knee joint with variable reduction ratio and variable stiffness coupling according to claim 1, characterized in that, The connection between the output rod (324), the movable rod (323), and the input rod (322) is accomplished through the connecting rod shaft (325), the copper washer (326), the copper baffle (327), and the needle roller bearing.

4. The humanoid robot knee joint with variable reduction ratio and variable stiffness coupling according to claim 3, characterized in that, A needle roller bearing is pressed into each end of the movable rod (323). A connecting rod shaft (325), a copper washer (326), and a copper baffle (327) are installed at corresponding positions on the input rod (322) and the output rod (324). The copper washer (326) and the copper baffle (327) clamp the needle roller bearing. The input rod (322), the movable rod (323), and the output rod (324) are connected in sequence through the connecting rod shaft (325) and the needle roller bearing.

5. The humanoid robot knee joint with variable reduction ratio and variable stiffness coupling according to claim 4, characterized in that, The output rod (324) is axially positioned by an output shaft baffle (321) at one end of the output shaft (315).

6. The humanoid robot knee joint with variable reduction ratio and variable stiffness coupling according to claim 1, characterized in that, The upper part of the left plate (302) and right plate (303) of the input shaft seat is connected to the input shaft seat cover plate (305).

7. The humanoid robot knee joint with variable reduction ratio and variable stiffness coupling according to claim 1, characterized in that, It also includes a base plate (6), on which the motor module guide rail base plate (107), push rod fixing seat (203), input shaft base plate (313), and output shaft seat base plate (318) are all mounted.

8. The humanoid robot knee joint with variable reduction ratio and variable stiffness coupling according to claim 1, characterized in that, The height of the push rod (201) is consistent with the center height of the motor end pulley (104) and the connecting rod end pulley (310).

9. The humanoid robot knee joint with variable reduction ratio and variable stiffness coupling according to claim 1, characterized in that, The diameter of the output shaft (315) is smaller than that of the input shaft (301).

10. The humanoid robot knee joint with variable reduction ratio and variable stiffness coupling according to claim 1, characterized in that, The variable four-bar linkage speed ratio module (3) also includes an encoder (320), which is installed on the outside of the left plate (316) of the output shaft seat and is connected to the other end of the output shaft (315).

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