Humanoid robot lower limb mechanism and working method thereof

Abstract

The invention discloses a humanoid robot lower limb mechanism and a working method thereof, solves the problem that a connecting rod force arm is small due to the fact that the position of a robot knee joint motor is too high in the prior art, and has the beneficial effect of enlarging the motion range of knee joints. The first power source is connected with the first rocker arm, the first rocker arm is connected with one end of the knee joint connecting rod, the other end of the knee joint connecting rod is connected with the first connecting rod shaft, the end, close to the thigh part, of the shank part supports the second connecting rod shaft, the thigh part supports the thigh gear shaft, and the shank part supports the shank gear shaft. The gear section of the thigh gear shaft is meshed with the gear section of the shank gear shaft, one end of the first connecting rod is rotationally connected with the first connecting rod shaft, the other end of the first connecting rod is rotationally connected with the thigh gear shaft, one end of the second connecting rod is rotationally connected with the first connecting rod shaft, and the other end of the second connecting rod is rotationally connected with the second connecting rod shaft.

Description

Technical Field

[0001] The present invention relates to the technical field of robots, and in particular to a lower limb mechanism of a humanoid robot and its working method. Background Art

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

[0003] Humanoid robots have good terrain adaptability and flexible operation capabilities, and can replace human work in many industrial fields in the future, with broad application prospects. Therefore, in recent years, the research and development of humanoid robots have received more and more attention from research institutions and enterprises. During the squatting and standing up movement of a person, the range of motion of the knee joint is very large, approaching 180°, and at the same time, the contact point between the thigh bone and the calf bone is constantly changing. When a person is in a deep squatting posture, the angle between the thigh and the calf is very small, and a very large torque is required for the knee joint to stand up. At this time, the contact point between the thigh bone and the calf bone is behind, and the tendon connecting the quadriceps femoris is relatively far from the contact point, with a large moment arm, which helps a person to stand up.

[0004] One of the existing knee joint drive schemes for humanoid robots is to directly install a drive motor at the knee joint. This drive method can make the knee joint have a large range of motion, but the rotational inertia of the leg relative to the hip joint is large, reducing the motion performance of the robot. Another commonly used knee joint drive scheme is to install the knee joint motor (CN202410243993.9, application date is March 4, 2024) at the hip joint and drive the knee joint to rotate through a four-bar linkage mechanism, or use a linear actuator installed inside the thigh (CN202311080903.0, application date is August 25, 2023) to drive the knee joint to rotate. The linear actuator, the thigh rod, and the calf rod form a four-bar linkage mechanism. Although the knee joint can be bent or straightened, in order to avoid the four-bar linkage mechanism approaching the singular point position to ensure better force transmission performance, in fact, a large range of motion of the knee joint cannot be achieved; moreover, when the robot is in a deep squat, the connecting rod moves linearly, and the distance between the connecting rod and the knee joint rotation axis is relatively close, resulting in a small moment arm of the connecting rod. And the robot needs a very large knee joint torque from squatting to standing up, and the small moment arm of the connecting rod significantly increases the peak torque of the knee joint motor, making the knee joint motor work under very harsh working conditions. Summary of the Invention

[0005] Aiming at the deficiencies of the existing technology, the purpose of the present invention is to provide a lower limb mechanism of a humanoid robot, which not only ensures the motion performance of the leg but also significantly improves the working conditions of the knee joint motor.

[0006] To achieve the above purpose, the present invention is realized through the following technical solutions: A lower limb mechanism of a humanoid robot, comprising a thigh part and a calf part. One end of the thigh part far from the calf part is provided with a first power source, the first power source is connected to a first rocker arm, one end of the first rocker arm is connected to one end of a knee joint connecting rod, the other end of the knee joint connecting rod is connected to a first connecting rod shaft, one end of the calf part near the thigh part supports a second connecting rod shaft, the thigh part supports a thigh gear shaft, the calf part supports a calf gear shaft, the gear sections of the thigh gear shaft and the calf gear shaft mesh with each other, one end of a first connecting rod is rotatably connected to the first connecting rod shaft, the other end of the first connecting rod is rotatably connected to the thigh gear shaft, one end of a second connecting rod is rotatably connected to the first connecting rod shaft, the other end of the second connecting rod is rotatably connected to the second connecting rod shaft. When the first power source works, the calf part is pushed to swing relative to the thigh part through the first rocker arm, the knee joint connecting rod, the first connecting rod and the second connecting rod.

[0007] For a lower limb mechanism of a humanoid robot as described above, the central axis of the thigh gear shaft is arranged higher than the central axis of the calf gear shaft; When the bionic humanoid robot stands, the central axis of the first connecting rod shaft is higher than the central axis of the second connecting rod shaft, the central axis of the second connecting rod shaft is located on the front side of the central axis of the first connecting rod shaft, and the central axis of the second connecting rod shaft is higher than the central axis of the calf gear shaft.

[0008] For a lower limb mechanism of a humanoid robot as described above, the shaft sections on both sides of the gear section in the thigh gear shaft and the calf gear shaft are connected by a third connecting rod, and both the thigh gear shaft and the calf gear shaft are rotatably connected to the third connecting rod.

[0009] For a lower limb mechanism of a humanoid robot as described above, a support fork is arranged at one end of the calf part near the thigh part. The support fork has an inclined section, the top of the inclined section is provided with the second connecting rod shaft, the bottom of the inclined section is provided with the calf gear shaft, the support fork supports the second connecting rod shaft and the calf gear shaft, and the third connecting rod is located inside the support fork; Wear-resistant gaskets are arranged between the inner side of the support fork and the third connecting rod, and between the third connecting rod and the gear section of the calf gear shaft.

[0010] For a lower limb mechanism of a humanoid robot as described above, the knee joint connecting rod is connected to the middle section of the first connecting rod shaft, the second connecting rod and the first connecting rod are sequentially arranged on the two side shaft sections of the first connecting rod shaft from the inside to the outside, and the shaft sections of the first connecting rod shaft rotatably support the second connecting rod and the first connecting rod.

[0011] For a lower limb mechanism of a humanoid robot as described above, the thigh part includes a left thigh cover and a right thigh cover. The left thigh cover and the right thigh cover are snap-connected. One end of the left thigh cover and the right thigh cover near the calf part is bent outward, and the inner holes of the bent ends of the left thigh cover and the right thigh cover cooperate with the two end special-shaped shaft sections of the thigh gear shaft to form circumferential fixation.

[0012] A lower limb mechanism of a humanoid robot as described above, wherein the first rocker arm is installed at the output end of the first power source. A first short shaft is provided at one end of the first rocker arm away from its rotation axis, and the first short shaft is rotatably connected to the knee joint link. Shaft end retaining rings are provided at the ends of the first link shaft and the second link shaft. Wear-resistant gaskets are provided between the knee joint link and the second link, between the second link and the first link, and between the first link and the corresponding shaft end retaining ring. Wear-resistant gaskets are provided on both sides of the second link with respect to the second link shaft.

[0013] A lower limb mechanism of a humanoid robot as described above further includes a sole. The sole is connected to the calf portion. A second power source is provided in the calf portion. The second power source is connected to a second rocker arm. The second rocker arm is rotatably connected to the sole through an ankle joint link. The calf portion, the second rocker arm, the ankle joint link, and the sole form a four-bar linkage.

[0014] In a second aspect, the present invention further provides a working method of a lower limb mechanism of a humanoid robot, including the following content: During the movement of the robot, the first power source drives the first rocker arm to rotate. Through the knee joint link, the first link, and the second link, the calf portion is driven to rotate relative to the thigh portion around the central axis of the thigh gear shaft. During the process of the robot changing from the standing posture to the knee-bent state, the meshing point of the thigh gear shaft and the calf gear shaft, that is, the force application point between the thigh portion and the calf portion, continuously moves backward to the rear of the robot, continuously increasing the lever arm of the knee joint link relative to the meshing point of the thigh gear shaft and the calf gear shaft, always maintaining good force transmission characteristics of the knee joint, and significantly reducing the peak torque of the first power source.

[0015] The beneficial effects of the present invention are as follows: 1) In the lower limb structure provided by the present invention, the first power source is placed at one end of the thigh portion away from the calf portion, equivalent to the hip joint, reducing the rotational inertia of the leg. The first rocker arm, the knee joint link, the first link, and the thigh portion form a four-bar linkage. The first link, the second link, the third link, and the calf portion form another four-bar linkage. Thus, a composite linkage mechanism is formed. The first power source, the first rocker arm, the knee joint link, the first link, and the second link form a knee joint drive mechanism, which can effectively drive the movement of the calf portion relative to the thigh portion. Because a set of linkage mechanisms is located between the thigh portion and the calf portion, the calf portion can perform a bending movement of 0° - 180° relative to the thigh portion, significantly increasing the movement range of the knee joint and improving the movement performance of the humanoid robot.

[0016] 2) In the present invention, it is considered that when a person is in a deep squatting position, the contact point is at the rear, and the patella is relatively far from the contact point. As the person gradually stands up, the contact point continuously approaches the patella. When the person gradually stands up from the deep squatting posture, the contact point between the femur and the tibia continuously moves from the rear to the front, and the torque at the knee joint gradually decreases. By supporting a pair of meshing gears through the thigh gear shaft and the calf gear shaft at the knee joint of the humanoid robot, when the humanoid robot gradually stands up from the deep squatting posture, the force application point between the thigh part and the calf part can continuously move from the rear to the front, achieving a high imitation of the human squatting and standing up movements. During this process, the four-bar linkage mechanism composed of the first link, the second link, the calf part, and the third link ensures that the knee joint link always has a large force arm, not only reducing the peak torque of the first power source but also significantly improving the working condition of the first power source.

[0017] 3) In the present invention, the structure of the first link shaft is reasonably arranged. The first link shaft is provided with the first link and the second link. The first link is rotatably connected to the thigh gear shaft, and the second link is connected to the second link shaft, ensuring the arrangement of the linkage mechanism to push the second link shaft to act and further drive the movement of the calf part when the knee joint link acts.

[0018] 4) In the present invention, the structure of the calf part is reasonably arranged. An inclined section is provided at the top of the calf part. The second link shaft is provided at the top of the inclined section, and the calf gear shaft is provided at the bottom of the inclined section, which is beneficial to the arrangement of the four-bar linkage mechanism. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The accompanying drawings forming a part of the present invention are used to provide a further understanding of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation to the present invention.

[0020] Figure 1 is the front view of a lower limb mechanism of a humanoid robot according to one or more embodiments of the present invention.

[0021] Figure 2 is the schematic diagram of a lower limb mechanism of a humanoid robot according to one or more embodiments of the present invention.

[0022] Figure 3 is the present invention Figure 1 the schematic diagram at the A-A cross-section in

[0023] Figure 4 is the present invention Figure 1 the schematic diagram at the B-B cross-section in

[0024] Figure 5 is another schematic diagram of a lower limb mechanism of a humanoid robot according to one or more embodiments of the present invention.

[0025] Figure 6 is the present inventionFigure 5 Explosion schematic diagram after magnification at position E in the figure.

[0026] Figure 7 It is the present invention Figure 2 Magnification schematic diagram at position C in the figure.

[0027] Figure 8 It is a schematic diagram after removing the thigh part in the lower limb mechanism of a humanoid robot according to one or more embodiments of the present invention.

[0028] Figure 9 It is the present invention Figure 8 Magnification schematic diagram at position D in the figure.

[0029] Figure 10 It is a kinematic schematic diagram of a humanoid robot in an upright state in the lower limb mechanism of a humanoid robot according to one or more embodiments of the present invention.

[0030] Figure 11 It is a kinematic schematic diagram of a humanoid robot during knee flexion in the lower limb mechanism of a humanoid robot according to one or more embodiments of the present invention.

[0031] In the figure: The distances or sizes between each part are exaggerated for showing the positions of each part, and the schematic diagram is only for illustration.

[0032] Among them: 101. Knee joint motor, 102. First rocker arm, 103. First bearing, 104. Knee joint connecting rod, 105. Thigh part, 1051. Left thigh cover, 1052. Right thigh cover, 106. First connecting rod, 107. Second connecting rod, 108. Third connecting rod, 109. Calf part, 110. Ankle joint motor, 111. Second bearing, 112. Second rocker arm, 113. Ankle joint connecting rod, 114. Sole, 115. Support fork, 116. Arc part; 201. Axial end retaining ring, 202. First wear-resistant gasket, 203. Third bearing, 204. First connecting rod shaft, 205. Second wear-resistant gasket, 206. Second connecting rod shaft, 301. Thigh gear shaft, 302. Calf gear shaft, 303. Fixed plate, 304. Third wear-resistant gasket. Detailed implementation manners

[0033] It should be noted that the following detailed description is exemplary and is intended to provide further illustration of the present invention. Unless otherwise specified, all technical and scientific terms used in the present invention have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present invention belongs.

[0034] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present invention. As used herein, unless the present invention clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should also be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof; As introduced in the background art, in the prior art, there is a problem that the range of motion of the knee joint of a humanoid robot is limited after the power source of the knee joint is moved upward. To solve the above technical problems, the present invention proposes a lower limb mechanism for a humanoid robot.

[0035] Embodiment 1 In a typical embodiment of the present invention, refer to Figure 1 and Figure 2 As shown, a lower limb mechanism for a humanoid robot includes a thigh portion 105 and a calf portion 109. A first power source is provided at one end of the thigh portion 105 away from the calf portion 109. The first power source is connected to a first rocker arm 102. One end of the first rocker arm 102 is connected to one end of a knee joint link 104. The other end of the knee joint link 104 is connected to a first link shaft. One end of the calf portion 109 near the thigh portion 105 supports a second link shaft 206. The thigh portion 105 supports a thigh gear shaft 301. The calf portion 109 supports a calf gear shaft 302. The gear segments of the thigh gear shaft 301 and the calf gear shaft 302 mesh with each other. Refer to Figure 3 As shown, one end of a first link 106 is rotatably connected to a first link shaft 204. The other end of the first link 106 is rotatably connected to the thigh gear shaft 301. One end of a second link 107 is rotatably connected to the first link shaft 204. The other end of the second link 107 is rotatably connected to the second link shaft 206. When the first power source works, the calf portion 109 is pushed to swing relative to the thigh portion 105 through the first rocker arm 102, the knee joint link 104, the first link 106, and the second link 107. The first power source is a knee joint motor 101. The knee joint motor 101, the first rocker arm 102, the knee joint link 104, the first link 106, and the second link 107 form a knee joint drive mechanism.

[0036] Specifically, the thigh portion 105 is rigidly connected by two parts, a left thigh cover 1051 and a right thigh cover 1052. The thigh portion 105, the thigh gear shaft 301, the calf portion 109, the calf gear shaft 302, and a third link 108 form a knee joint support mechanism. The thigh gear shaft 301 serves as the knee joint axis.

[0037] Refer to Figure 4 、 Figure 5 and Figure 6As shown, the thigh part 105 is connected to the calf part 109 through the third connecting rod 108. A first gear is arranged in the middle of the thigh gear shaft 301, and a second gear is arranged in the middle of the calf gear shaft 302. The first gear and the second gear are meshed. The two ends of the thigh gear shaft 301 are processed with special-shaped shaft sections, and the special-shaped shaft sections can be in a strip shape. The corresponding special-shaped grooves are processed at the shaft holes at the lower ends of the left thigh cover 1051 and the right thigh cover 1052. The special-shaped shaft sections at the two ends of the thigh gear shaft 301 are matched with the special-shaped grooves of the shaft holes at the lower ends of the left thigh cover 1051 and the right thigh cover 1052 for circumferential fixation. Threaded holes are processed on the two end faces of the thigh gear shaft 301, and the left thigh cover 1051, the right thigh cover 1052 and the thigh gear shaft are fixedly connected by screws; On both sides of the middle tooth section of the thigh gear shaft 301, the third connecting rod 108 and the first connecting rod 106 are sequentially arranged outward. Both the first connecting rod 106 and the third connecting rod 108 are rotatably connected to the thigh gear shaft 301; third bearings 203 are installed between the thigh gear shaft 301 and the third connecting rod 108 and the first connecting rod 106 respectively. Third wear-resistant gaskets 304 are arranged between the middle tooth section of the thigh gear shaft 301 and the third connecting rod 108, between the third connecting rod and the first connecting rod 106, and between the third connecting rod and the left thigh cover 1051 and the right thigh cover 1052.

[0038] It is easily understandable that special-shaped shaft sections are processed at both ends of the calf gear shaft 302, and special-shaped grooves matching the special-shaped shaft sections of the calf gear shaft 302 are processed on the calf part 109 and the fixing plate 303. Circumferential fixation is carried out through the cooperation of the special-shaped grooves and the special-shaped shaft sections. Threaded holes are processed on the two end faces of the calf gear shaft 302, and the calf gear shaft 302 is fixedly connected to the calf part 109 and the fixing plate 303 by screws. The middle tooth section of the calf gear shaft 302 supports the third connecting rod 108 through the third bearings 203 on both sides of the shaft section. Third wear-resistant gaskets 304 are arranged between the middle tooth section of the calf gear shaft 302 and the third connecting rod 108, between the third connecting rod and the calf part 109, and between the third connecting rod and the fixing plate 303. The third wear-resistant gasket 304 located on the side of the third connecting rod is a whole piece, covering the thigh gear shaft 301 and the calf gear shaft 302.

[0039] Furthermore, the knee joint motor 101 is installed at the upper end of the thigh part 105. The first rocker arm 102 is installed at the output end of the knee joint motor 101. A first short shaft extends from the end of the first rocker arm 102 far from the rotation axis. The first short shaft is connected to one end of the knee joint connecting rod 104, and the first short shaft is parallel to the central axis of the knee joint motor 101; One end of the thigh part 105 close to the calf part 109 is provided with a first connecting rod shaft 204. The other end of the knee joint connecting rod 104 is rotationally connected to the first connecting rod shaft 204 through a first bearing 103. Two second connecting rods 107 are rotationally connected to the first connecting rod shaft 204 through third bearings 203 and are symmetrically arranged on both sides of the knee joint connecting rod 104. Two first connecting rods 106 are rotationally connected to the first connecting rod shaft 204 through third bearings 203 and are symmetrically arranged outside the two second connecting rods 107. Second wear-resistant gaskets 205 are arranged between the connecting rods. Threaded holes are respectively machined on both end faces of the first connecting rod shaft 204. Each connecting rod is axially fixed by screws and an end shaft retaining ring 201. A first wear-resistant gasket 202 is arranged between the end shaft retaining ring 201 and the first connecting rod 106. The other ends of the two first connecting rods 106 are rotationally connected to the thigh gear shaft 301 through third bearings 203. The other ends of the two second connecting rods 107 are rotationally connected to the second connecting rod shaft 206 through third bearings 203. The second connecting rod shaft 206 is installed in the shaft hole at the upper end of the calf part 109. Threaded holes are machined on both end faces of the second connecting rod shaft 206 and are fixed to the calf part 109 through two end shaft retaining rings 201 and screws.

[0040] It should be noted that, referring to Figure 7 As shown, after the left thigh cover 1051 and the right thigh cover 1052 are butted, the interior is hollow to set the knee joint connecting rod 104. One end of the left thigh cover and the right thigh cover in the thigh part 105 close to the calf part is bent outward so that the distance between the left thigh cover 1051 and the right thigh cover 1052 is increased to set components such as the first connecting rod and the second connecting rod. The width of the thigh part 105 gradually becomes narrower on the side close to the calf part 109.

[0041] Referring to Figure 8 and Figure 9 As shown, an arc part 116 is arranged on the side of the calf part 109 close to the thigh part 105 to simulate the patella of a human. One end of the calf part 109 close to the thigh part 105 is provided with a support fork 115. The support fork 115 has an inclined section. The top of the inclined section is provided with a second connecting rod shaft, and the second connecting rod shaft is arranged close to the arc part 116. The bottom of the inclined section is provided with a calf gear shaft, and the third connecting rod is located inside the support fork.

[0042] In this embodiment, the central axis of the thigh gear shaft 301 is set higher than the central axis of the calf gear shaft 302; when the humanoid robot stands, the central axis of the first connecting rod shaft 204 is higher than the central axis of the second connecting rod shaft 206. The central axis of the second connecting rod shaft 206 is located in front of the central axis of the first connecting rod shaft 204. The central axis of the second connecting rod shaft 206 is higher than the central axis of the calf gear shaft 302, ensuring the movement range of the four-bar mechanism composed of the first connecting rod 106, the second connecting rod 107 and the calf part 109; Referring toFigure 1 As shown in the figure, the lower end of the calf part 109 is rotatably connected to the sole 114. A second power source is installed near the knee joint of the calf part 109. The second power source is the ankle joint motor 110. The output end of the ankle joint motor 110 is installed with a second rocker arm 112. One end of the second rocker arm 112 far from the rotation axis is provided with a second short shaft parallel to the axis of the ankle joint motor 110. One end of the ankle joint connecting rod 113 is rotatably connected to the second short shaft through a second bearing 111, and the other end of the ankle joint connecting rod 113 is rotatably connected to the sole 114 through a second bearing 111. The calf part 109, the second rocker arm 112, the ankle joint connecting rod 113 and the sole form a regular four-bar linkage mechanism. When the ankle joint motor 110 rotates, the sole 114 is driven by the ankle joint connecting rod 113 to swing up and down relative to the calf part 109 to achieve good contact with the ground.

[0043] As Figure 10 、 Figure 11 shown, when the robot stands, the thigh part 105 and the calf part 109 are on the vertical line, and the knee joint torque is almost zero. During the movement of the robot, the knee joint motor 101 drives the first rocker arm 102 to rotate, and drives the calf part 109 to rotate relative to the thigh part 105 through the knee joint connecting rod 104 and the second connecting rod 107. During the process of the robot bending its knees from the standing posture, the meshing point of the thigh gear shaft 301 and the calf gear shaft 302, that is, the force application point between the thigh part 105 and the calf part 109, continuously moves to the right, which is similar to the contact point between the thigh and the calf moving away from the patella during the process of a person squatting down, continuously increasing the lever arm of the force of the knee joint connecting rod 104 relative to the meshing point of the thigh gear shaft 301 and the calf gear shaft 302, always maintaining good force transmission characteristics at the knee joint, and significantly reducing the peak torque of the knee joint motor 101.

[0044] Embodiment 2 This embodiment discloses a working method of a lower limb mechanism of a humanoid robot. Referring to Figure 10 and Figure 11 shown, it includes the following contents: During the movement of the robot, the first power source drives the first rocker arm 102 to rotate, and drives the calf part 109 to rotate around the central axis of the thigh gear shaft relative to the thigh part 105 through the knee joint connecting rod 104, the first connecting rod 106 and the second connecting rod 107. During the process of the robot changing from the standing posture to the knee-bending state, the meshing point of the thigh gear shaft 301 and the calf gear shaft 302, that is, the force application point between the thigh part and the calf part, continuously moves to the rear side of the robot, continuously increasing the lever arm of the knee joint connecting rod relative to the meshing point of the thigh gear shaft and the calf gear shaft, always maintaining good force transmission characteristics at the knee joint, and significantly reducing the peak torque of the first power source.

[0045] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A lower limb mechanism of a humanoid robot, characterized in that, It includes a thigh part and a calf part. A first power source is provided at one end of the thigh part away from the calf part. The first power source is connected to a first rocker arm. One end of the first rocker arm is connected to one end of a knee joint connecting rod. The other end of the knee joint connecting rod is connected to a first connecting rod shaft. One end of the calf part near the thigh part supports a second connecting rod shaft. The thigh part supports a thigh gear shaft. The calf part supports a calf gear shaft. The gear sections of the thigh gear shaft and the calf gear shaft mesh with each other. One end of a first connecting rod is rotatably connected to the first connecting rod shaft. The other end of the first connecting rod is rotatably connected to the thigh gear shaft. One end of a second connecting rod is rotatably connected to the first connecting rod shaft. The other end of the second connecting rod is rotatably connected to the second connecting rod shaft. When the first power source works, the calf part is pushed to swing relative to the thigh part through the first rocker arm, the knee joint connecting rod, the first connecting rod and the second connecting rod.

2. The lower limb mechanism of a humanoid robot according to claim 1, characterized in that, The central axis of the thigh gear shaft is arranged higher than the central axis of the calf gear shaft; When the bionic humanoid robot stands, the central axis of the first connecting rod shaft is higher than the central axis of the second connecting rod shaft. The central axis of the second connecting rod shaft is located on the front side of the central axis of the first connecting rod shaft. The central axis of the second connecting rod shaft is higher than the central axis of the calf gear shaft.

3. The lower limb mechanism of a humanoid robot according to claim 1, characterized in that, The shaft sections on both sides of the gear section between the thigh gear shaft and the calf gear shaft are connected by a third connecting rod. Both the thigh gear shaft and the calf gear shaft are rotatably connected to the third connecting rod.

4. The lower limb mechanism of a humanoid robot according to claim 3, characterized in that, One end of the calf part near the thigh part is provided with a support fork. The support fork has an inclined section. The top of the inclined section is provided with the second connecting rod shaft. The bottom of the inclined section is provided with the calf gear shaft. The third connecting rod is located inside the support fork; Wear-resistant gaskets are provided between the inner side of the support fork and the third connecting rod, and between the third connecting rod and the gear section of the calf gear shaft.

5. A lower limb mechanism of a humanoid robot according to claim 1, characterized in that, The knee joint connecting rod is connected to the middle section of the first connecting rod shaft. The second connecting rod and the first connecting rod are sequentially arranged on the two side shaft sections of the first connecting rod shaft from the inside to the outside. The shaft sections of the first connecting rod shaft rotatably support the second connecting rod and the first connecting rod.

6. The lower limb mechanism of a humanoid robot according to claim 1, characterized in that, The thigh part includes a left thigh cover and a right thigh cover. The left thigh cover and the right thigh cover are snap-connected. One end of the left thigh cover and the right thigh cover near the calf part is bent outward. The inner parts of the bent ends of the left thigh cover and the right thigh cover cooperate with the special-shaped shaft sections at both ends of the thigh gear shaft to form circumferential fixation.

7. A lower limb mechanism of a humanoid robot according to claim 1, characterized in that, The first rocker arm is installed at the output end of the first power source. A first short shaft is provided at one end of the first rocker arm away from its rotation axis. The first short shaft is rotatably connected to the knee joint connecting rod.

8. The lower limb mechanism of a humanoid robot according to claim 7, characterized in that, Axial end retaining rings are provided at the ends of the first connecting rod shaft and the second connecting rod shaft. Wear-resistant gaskets are provided between the knee joint connecting rod and the second connecting rod, between the second connecting rod and the first connecting rod, and between the first connecting rod and the corresponding axial end retaining ring; Wear-resistant gaskets are provided on both sides of the second connecting rod on the second connecting rod shaft.

9. The lower limb mechanism of a humanoid robot according to claim 1, characterized in that, It further includes a sole. The sole is connected to the calf part. A second power source is provided on the calf part. The second power source is connected to a second rocker arm. The second rocker arm is rotatably connected to the sole through an ankle joint connecting rod. The calf part, the second rocker arm, the ankle joint connecting rod and the sole form a four-bar mechanism.

10. A working method of a lower limb mechanism of a humanoid robot according to any one of claims 1-9, characterized in that, It includes the following contents: During the movement of the robot, the first power source drives the first rocker to rotate. Through the knee joint link, the first link, and the second link, the lower leg is driven to rotate relative to the thigh around the central axis of the thigh gear shaft. During the process of the robot changing from the standing posture to the knee-bending state, the meshing point of the thigh gear shaft and the lower leg gear shaft, which is the force application point between the thigh and the lower leg, continuously moves backward along the robot, continuously increasing the lever arm of the knee joint link relative to the meshing point of the thigh gear shaft and the lower leg gear shaft, always maintaining good force transmission characteristics of the knee joint, and significantly reducing the peak torque of the first power source.

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