Robot knee joint based on tendon motion control

Abstract

A robot knee joint based on tendon motion control comprises a thigh structure, a shank structure and a knee joint rotating supporting shaft, the top of the shank structure is rotationally connected with the bottom of the thigh structure through the knee joint rotating supporting shaft, and one end of the joint rotating supporting shaft is fixedly installed at the top of the shank structure. At least one idle wheel wire coil is rotationally installed on the knee joint rotating supporting shaft, a knee joint output wire coil is further fixedly installed on the knee joint rotating supporting shaft, and the knee joint output wire coil is fixedly connected with the top of the shank structure. The shank structure is fixedly supported at the other end of the knee joint rotating supporting shaft through a knee joint output wire coil, and an encoder aligned with the knee joint rotating supporting shaft is further installed at the bottom of the thigh structure. The device is simple in structure and convenient to mount, demount and maintain subsequently, the idle wheel wire coils and the output wire coils do not interfere with each other, and stable operation can be achieved.

Description

Technical Field

[0001] This invention relates to the technical field of humanoid robots, and specifically to a robotic knee joint based on tendon movement control. Background Technology

[0002] In the field of humanoid robot research and manufacturing, the joint drive solution is a key factor in the robot's stability, reliability, and cost-effectiveness. Currently, there are three main technical solutions for robot joint drives: One is hydraulic drive technology, represented by Boston Dynamics' Atlas robot, which has the advantages of high torque and fast response, but also has the disadvantages of high complexity, high cost and high weight. The second is the direct drive or linkage drive technology of motor joint modules. Most robot companies or institutions, such as Digit Robotics, Tesla Robotics and Unitree Robotics, use this technology. Its advantages are simple structure and low cost, but it may lack dynamic performance in some situations. Thirdly, there is tendon-driven technology that simulates human muscles, which can achieve more natural movements. However, this technology is difficult to control and currently has a short lifespan. Early examples include the iCub humanoid robot platform. In recent technology, patent document CN221391059 U discloses a robot joint transmission mechanism, including a first support, a first motor, a first input end, a first transmission belt, and a first output coil. The first motor is located at the upper end of the first support, and the first output coil is located at the lower end of the first support. The first input end includes a first input coil, and the power output end of the first motor is connected to the first input coil. The outer diameter of the first input coil is in the range of 15mm-45mm. The first transmission belt includes a first chain and a first pull cable. The first chain is connected to the first input coil, and the first pull cable is wound around the first output coil. It solves the problems of cable life and transmission torque in rope transmission. In the intermediate joint of its drive, namely the knee joint of the humanoid robot, it not only has to support various idler reels, but also its own joint output reel. Therefore, the joint is relatively complex, which is not convenient for installation, disassembly and subsequent maintenance. Moreover, the idler reels and output reels are arranged side by side, which can easily cause interference and is not conducive to stable operation. It is also prone to problems such as shaking and inaccurate control positioning. Summary of the Invention

[0003] To overcome the shortcomings of existing humanoid robot technology, this invention proposes a robot knee joint based on tendon motion control that is simple in structure, easy to install, disassemble and maintain, and ensures that the idler reels and output reels do not interfere with each other, thus enabling stable operation.

[0004] The specific technical solution is as follows: A robotic knee joint based on tendon motion control includes a thigh structure, a lower leg structure, and a knee joint rotation support shaft. The top of the lower leg structure is rotatably connected to the bottom of the thigh structure via the knee joint rotation support shaft. One end of the joint rotation support shaft is fixedly mounted on the top of the lower leg structure. At least one idler gear reel is rotatably mounted on the knee joint rotation support shaft. A knee joint output reel is also fixedly mounted on the knee joint rotation support shaft and is fixedly connected to the top of the lower leg structure. The lower leg structure is fixedly supported on the other end of the knee joint rotation support shaft via the knee joint output reel. An encoder aligned with the knee joint rotation support shaft is also installed at the bottom of the thigh structure.

[0005] Preferably, a first joint support plate and a second joint support plate are provided at the bottom of the thigh structure. The first joint support plate and the second joint support plate are arranged at intervals relative to each other. The idler wheel and the knee joint output wheel are arranged side by side between the first joint support plate and the second joint support plate. The first joint support plate and the second joint support plate are respectively rotatably engaged with the knee joint rotation support shaft.

[0006] Preferably, the lower leg structure includes a lower leg support and a knee joint support shell. The knee joint support shell is disposed on the top of the lower leg support and has a first support plate shell and a second support plate shell. The first support plate shell and the second support plate shell are disposed at a distance from each other, and the knee joint rotation support shaft is disposed between the first support plate shell and the second support plate shell.

[0007] Preferably, one end face of the knee joint rotation support shaft is fixedly installed on the inner side of the first support plate shell by a screw structure, the knee joint output cable reel is fixedly installed on the inner side of the second support plate shell, and the knee joint output cable reel is disposed close to the second joint support plate. The upper side of the second support plate shell has a limiting opening, which is aligned with both sides of the second joint support plate. The first joint support plate is disposed on the inner side of the first support plate shell.

[0008] Preferably, the limiting opening has a curved oblique limiting part and an upright vertical limiting part. The curved oblique limiting part is located below the knee joint rotation support axis and is inclined downward towards the rear side of the lower leg structure. The upright vertical limiting part is located at the top of the curved oblique limiting part and in front of the knee joint rotation support axis. A soft pad structure is also installed on the upright vertical limiting part, and the soft pad structure is arranged on the side opposite to the upright second joint support plate.

[0009] Preferably, the first joint support plate and the second joint support plate are respectively mounted on the two ends of the knee joint rotation support shaft via angular contact bearings.

[0010] Preferably, a through hole is provided at the center of the knee joint rotation support shaft and at the corresponding position of the first support plate shell. A radial magnet is installed at the end of the through hole of the knee joint rotation support shaft. The radial magnet is located close to the second joint support plate. An absolute encoder is installed on the outside of the second joint support plate by a screw structure. The absolute encoder is aligned with the radial magnet.

[0011] Preferably, the outer cylindrical surface of the knee joint rotation support shaft has a first cylindrical surface, a second cylindrical surface, a third cylindrical surface, and an outer ring limiting plate in sequence, and the diameters of the first cylindrical surface, the second cylindrical surface, the third cylindrical surface, and the outer ring limiting plate increase in sequence. The knee joint output coil is interference-fitted on the second cylindrical surface, and the idler coil is rotatably mounted on the first cylindrical surface through a bearing. Joint mounting holes are provided on the first joint support plate and the second joint support plate, and angular contact bearings are respectively provided in the joint mounting holes. Two angular contact bearings are respectively mounted on the first cylindrical surface and the third cylindrical surface. The outer ring limiting plate is set close to the inner ring of the angular contact bearing on the second joint support plate.

[0012] Preferably, an idler reel is rotatably mounted on the knee joint rotation support shaft. The idler reel has a through hole in its center, and an annular boss in the middle of the through hole divides the through hole into two bearing mounting holes. A left angular contact bearing and a right angular contact bearing are respectively installed in the bearing mounting holes. Both the left and right angular contact bearings are fitted onto the first cylindrical surface. A bushing or washer is provided between the inner ring of the left angular contact bearing and the inner ring of the angular contact bearing on the first joint support plate. The center of the knee joint output reel has a mounting hole. One side of the mounting hole is interference-fitted with the second cylindrical surface, and the other side of the mounting hole is provided with a limiting separator ring. The inner ring of the right angular contact bearing is positioned close to the limiting separator ring.

[0013] Preferably, a cable end locking hole is provided on the knee joint output cable reel, and a cable end locking seat is provided on the knee joint support housing. The cable end locking hole and the cable end locking seat respectively fix the two ends of the control cable.

[0014] The beneficial effects of this invention are as follows: one end of the joint rotation support shaft is fixedly installed on the top of the lower leg structure, and the other end of the knee joint rotation support shaft is supported on the other side of the top of the lower leg structure through the knee joint output cable reel. This not only facilitates installation, disassembly and subsequent maintenance, but also facilitates the rotation of the knee joint and the smooth operation of the idler wheel reel in the middle. This enhances the support stability of the joint rotation support shaft, avoids problems such as swaying and inaccurate control positioning during the control process, and is conducive to the overall balance and coordinated control of the robot. Furthermore, the outer circular surface of the knee joint rotation support shaft is composed of a first cylindrical surface, a second cylindrical surface, a third cylindrical surface with successively increasing diameters, and an outer ring limiting plate. These are used sequentially to limit the installation of the first joint support plate, the idler wheel reel, the knee joint output reel, and the second joint support plate. This facilitates sequential installation while ensuring that the rotation of each idler wheel reel and the output reel does not interfere with each other, and the structure is stable. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the overall three-dimensional structure of the robot's legs.

[0016] Figure 2 This is a schematic diagram of the overall cross-sectional structure of the present invention.

[0017] Figure 3 This is a schematic diagram of the overall rear structure of the present invention.

[0018] Figure 4 This is a side view of the overall structure of the present invention.

[0019] Figure 5 This is a schematic diagram of the installation structure of the knee joint output cable reel in this invention.

[0020] Figure 6 This is a schematic diagram of the cross-sectional structure of the knee joint rotation support shaft in this invention.

[0021] Figure 7 This is a schematic diagram of the thigh structure in this invention.

[0022] Explanation of reference numerals in the attached diagram: 1. Thigh structure; 2. Lower leg structure; 3. Knee joint rotation support shaft; 4. Idler wheel reel; 5. Knee joint output reel; 6. Absolute encoder; First joint support plate 11; Second joint support plate 12; Angular contact bearing 13; Joint mounting hole 14. 21. Lower leg support; 22. Knee joint support shell; 23. First support plate shell; 24. Second support plate shell; 25. Limiting opening; 26. Cable end holder; Curved oblique limiting part 251; Vertical limiting part 252; Threaded hole 31; radial magnet 32; first cylindrical surface 33; second cylindrical surface 34; third cylindrical surface 35; outer ring limiting plate 36; Bearing mounting hole 41; left angular contact bearing 42; right angular contact bearing 43; pull wire end clip hole 51. Detailed Implementation

[0023] The preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, so that the advantages and features of the present invention can be more easily understood by those skilled in the art, thereby providing a clearer and more explicit definition of the scope of protection of the present invention.

[0024] In the description of this invention, it should be noted that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0025] In the description of this invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can be a direct connection or a connection through an intermediate medium; or they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances. Example

[0026] like Figure 1 , Figure 2 , Figure 3 , Figure 4 , Figure 5 , Figure 6 and Figure 7 As shown: A robotic knee joint based on tendon motion control includes a thigh structure 1, a lower leg structure 2, and a knee joint rotation support shaft 3. The top of the lower leg structure 2 is rotatably connected to the bottom of the thigh structure 1 via the knee joint rotation support shaft 3. One end of the joint rotation support shaft 3 is fixedly mounted on the top of the lower leg structure 2. An idler gear reel 4 is rotatably mounted on the knee joint rotation support shaft 3 to control the cable transfer of the foot structure for smooth control. If the foot structure or other structures have multiple degrees of freedom that need to be controlled, multiple idler gear reels 4 can be rotatably mounted on the knee joint rotation support shaft 3. A knee joint output reel 5 is also fixedly mounted on the knee joint rotation support shaft 3. The knee joint output reel 5 is connected to the lower leg structure 2. The lower leg structure 2 is fixedly connected at the top and supported at the other end of the knee joint rotation support shaft 3 via the knee joint output cable reel 5. This facilitates the rotation of the knee joint and ensures smooth operation of the idler wheel reel 4 in the middle, avoiding inaccurate control positioning issues such as shaking during control. This is beneficial for the overall balance and coordinated control of the robot. Furthermore, only one end of the joint rotation support shaft is fixedly installed at the top of the lower leg structure. The indirect support via the knee joint output cable reel 5 does not affect the stability of the knee joint rotation support shaft 3, and may even enhance its stability. This facilitates installation, disassembly, and subsequent maintenance. An encoder aligned with the knee joint rotation support shaft 3 is also installed at the bottom of the thigh structure 1 to provide feedback on the movement status of the knee joint.

[0027] A first joint support plate 11 and a second joint support plate 12 are provided at the bottom of the thigh structure 1. The first joint support plate 11 and the second joint support plate 12 are arranged at intervals relative to each other. The idler pulley spool 4 and the knee joint output spool 5 are arranged side by side between the first joint support plate 11 and the second joint support plate 12. The first joint support plate 11 and the second joint support plate 12 are respectively rotatably engaged with the knee joint rotation support shaft 3, which makes the joint support more stable and is conducive to the smooth support of the knee joint rotation support shaft 3. The first joint support plate 11 and the second joint support plate 12 are respectively rotatably mounted at both ends of the knee joint rotation support shaft 3 through angular contact bearings 13.

[0028] The outer surface of the aforementioned knee joint rotation support shaft 3 sequentially comprises a first cylindrical surface 33, a second cylindrical surface 34, a third cylindrical surface 35, and an outer ring limiting disc 36, with the diameters of the first cylindrical surface 33, the second cylindrical surface 34, the third cylindrical surface 35, and the outer ring limiting disc 36 increasing sequentially. The knee joint output cable spool 5 is interference-fitted onto the second cylindrical surface 34, and the idler cable spool 4 is rotatably mounted on the first cylindrical surface 33 via bearings. Joint mounting holes 14 are respectively provided on the first joint support plate 11 and the second joint support plate 12. Angular contact bearings 13 are respectively installed on the first cylindrical surface 33 and the third cylindrical surface 35. The outer ring limiting plate 36 is set close to the inner ring of the angular contact bearings 13 on the second joint support plate 12. This is conducive to the rotation of each idler wheel spool and the output spool without interference. The idler wheel spool and the output spool can rotate independently or rotate simultaneously without interference. That is, while bending the knee, the relative angle of the foot plate is rotated, making the movement more coordinated and natural. Moreover, the knee joint structure itself is more stable and it is also easier to install in an orderly manner.

[0029] The idler coil 4 has a through hole in its center. An annular boss in the middle of the through hole divides the through hole into two bearing mounting holes 41. A left angular contact bearing 42 and a right angular contact bearing 43 are respectively installed in the bearing mounting holes 41. Both the left angular contact bearing 42 and the right angular contact bearing 43 are sleeved on the first cylindrical surface 33. A bushing or washer is provided between the inner ring of the left angular contact bearing 42 and the inner ring of the angular contact bearing 13 on the first joint support plate 11. The knee joint output coil 5 has a mounting hole in its center. One side of the mounting hole is interference-fitted with the second cylindrical surface 34, and the other side of the mounting hole is provided with a limiting separation ring. The inner ring of the right angular contact bearing 43 is set close to the limiting separation ring.

[0030] Furthermore, the lower leg structure 2 includes a lower leg bracket 21 and a knee joint support shell 22. The knee joint support shell 22 is disposed on the top of the lower leg bracket 21, and the knee joint support shell 22 has a first support plate shell 23 and a second support plate shell 24. The first support plate shell 23 and the second support plate shell 24 are arranged at intervals relative to each other, and the knee joint rotation support shaft 3 is disposed between the first support plate shell 23 and the second support plate shell 24.

[0031] The knee joint rotation support shaft 3 has one end face fixedly installed on the inner side of the first support plate shell 23 by a screw structure. That is, the first support plate shell 23 is evenly provided with mounting holes, and the knee joint rotation support shaft 3 has corresponding threaded holes 31 evenly provided on one end face. The mounting holes are provided with screw structures, and the screw structures pass through the mounting holes and cooperate with the threaded holes 31.

[0032] The knee joint output cable reel 5 is fixedly installed on the inner side of the second support plate shell 24 by a uniformly arranged screw structure, and the knee joint output cable reel 5 is set close to the second joint support plate 12. That is, the second support plate shell 24 indirectly supports the other end of the knee joint rotation support shaft 3 through the knee joint output cable reel 5. The upper side of the second support plate shell 24 has a limiting opening 25, which is aligned with both sides of the second joint support plate 12. The first joint support plate 11 is set inside the first support plate shell 23.

[0033] The aforementioned limiting opening 25 has a curved oblique limiting part 251 and an upright vertical limiting part 252. The curved oblique limiting part 251 is located below the knee joint rotation support shaft 3 and is inclined downward towards the rear side of the lower leg structure 2. The upright vertical limiting part 252 is located at the top of the curved oblique limiting part 251 and in front of the knee joint rotation support shaft 3. A soft pad structure is also installed on the upright vertical limiting part 252. The soft pad structure is located on the side opposite to the upright second joint support plate 12. The limiting opening 25 is located above the screw structure on which the knee joint output cable reel 5 is installed. Therefore, a continuous edge protective shell is provided on the second joint support plate 12, which not only embeds and protects the screw structure, but also widens the force-bearing area of ​​the curved oblique limiting part 251 and the upright vertical limiting part 252.

[0034] A through hole is provided at the center of the knee joint rotation support shaft 3 and at the corresponding position of the first support plate shell 23. A radial magnet 32 ​​is installed at the end of the through hole of the knee joint rotation support shaft 3. The radial magnet 32 ​​is set close to the second joint support plate 12. An absolute encoder 6 is installed on the outside of the second joint support plate 12 by a screw structure. The absolute encoder 6 is aligned with the radial magnet 32. The absolute encoder 6 and the radial magnet 32 ​​are used together and can easily remember the movement position of the knee joint after power failure.

[0035] A cable end locking hole 51 is provided on the knee joint output cable reel 5, and a cable end locking seat 26 is provided on the knee joint support housing 22. The cable end locking hole 51 and the cable end locking seat 26 respectively fix the two ends of the control cable. This makes it easier to lock the two ends of the cable during installation and avoids the cable from overlapping and interfering during movement, resulting in more stable movement control.

[0036] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims.

Claims

1. A robotic knee joint based on tendon motion control, characterized in that: The device includes a thigh structure (1), a calf structure (2), and a knee joint rotation support shaft (3). The top of the calf structure (2) is rotatably connected to the bottom of the thigh structure (1) via the knee joint rotation support shaft (3). One end of the joint rotation support shaft (3) is fixedly installed on the top of the calf structure (2). At least one idler reel (4) is rotatably installed on the knee joint rotation support shaft (3). A knee joint output reel (5) is also fixedly installed on the knee joint rotation support shaft (3). The knee joint output reel (5) is fixedly connected to the top of the calf structure (2). The calf structure (2) is fixedly supported on the other end of the knee joint rotation support shaft (3) via the knee joint output reel (5). An encoder aligned with the knee joint rotation support shaft (3) is also installed at the bottom of the thigh structure (1).

2. The robotic knee joint based on tendon motion control according to claim 1, characterized in that: A first joint support plate (11) and a second joint support plate (12) are provided at the bottom of the thigh structure (1). The first joint support plate (11) and the second joint support plate (12) are arranged at intervals. The idler wheel coil (4) and the knee joint output coil (5) are arranged side by side between the first joint support plate (11) and the second joint support plate (12). The first joint support plate (11) and the second joint support plate (12) are respectively rotatably engaged with the knee joint rotation support shaft (3).

3. The robotic knee joint based on tendon motion control according to claim 2, characterized in that: The lower leg structure (2) includes a lower leg support (21) and a knee joint support shell (22). The knee joint support shell (22) is disposed on the top of the lower leg support (21), and the knee joint support shell (22) has a first support plate shell (23) and a second support plate shell (24). The first support plate shell (23) and the second support plate shell (24) are arranged at a distance from each other. The knee joint rotation support shaft (3) is disposed between the first support plate shell (23) and the second support plate shell (24).

4. The robotic knee joint based on tendon motion control according to claim 3, characterized in that: One end face of the knee joint rotation support shaft (3) is fixedly installed on the inner side of the first support plate shell (23) by a screw structure. The knee joint output cable reel (5) is fixedly installed on the inner side of the second support plate shell (24), and the knee joint output cable reel (5) is set close to the second joint support plate (12). The upper side of the second support plate shell (24) has a limiting opening (25), which is aligned with both sides of the second joint support plate (12). The first joint support plate (11) is set on the inner side of the first support plate shell (23).

5. The robotic knee joint based on tendon motion control according to claim 4, characterized in that: The limiting opening (25) has a curved oblique limiting part (251) and an upright vertical limiting part (252). The curved oblique limiting part (251) is located below the knee joint rotation support shaft (3) and is inclined downward toward the rear side of the lower leg structure (2). The upright vertical limiting part (252) is located at the top of the curved oblique limiting part (251) and in front of the knee joint rotation support shaft (3). A soft pad structure is also installed on the upright vertical limiting part (252). The soft pad structure is arranged on the side opposite to the upright second joint support plate (12).

6. The robotic knee joint based on tendon motion control according to any one of claims 2-5, characterized in that: The first joint support plate (11) and the second joint support plate (12) are respectively mounted on the two ends of the knee joint rotation support shaft (3) via angular contact bearings (13).

7. The robotic knee joint based on tendon motion control according to claim 6, characterized in that: A through hole is provided at the center of the knee joint rotation support shaft (3) and at the corresponding position of the first support plate shell (23). A radial magnet (32) is installed at the end of the through hole of the knee joint rotation support shaft (3). The radial magnet (32) is located close to the second joint support plate (12). An absolute encoder (6) is installed on the outside of the second joint support plate (12) by a screw structure. The absolute encoder (6) is aligned with the radial magnet (32).

8. The robotic knee joint based on tendon motion control according to any one of claims 2-5 or 7, characterized in that: The outer circular surface of the knee joint rotation support shaft (3) has a first cylindrical surface (33), a second cylindrical surface (34), a third cylindrical surface (35), and an outer ring limiting plate (36) in sequence. The diameters of the first cylindrical surface (33), the second cylindrical surface (34), the third cylindrical surface (35), and the outer ring limiting plate (36) increase in sequence. The knee joint output coil (5) is interference-fitted on the second cylindrical surface (34). The idler coil (4) is rotatably mounted on the first cylindrical surface (33) through a bearing. Joint mounting holes (14) are provided on the first joint support plate (11) and the second joint support plate (12) respectively. Angular contact bearings (13) are respectively provided in the joint mounting holes (14). The two angular contact bearings (13) are respectively mounted on the first cylindrical surface (33) and the third cylindrical surface (35). The outer ring limiting plate (36) is set close to the inner ring of the angular contact bearing (13) on the second joint support plate (12).

9. The robotic knee joint based on tendon motion control according to claim 8, characterized in that: An idler wheel spool (4) is rotatably mounted on the knee joint rotation support shaft (3). The idler wheel spool (4) has a through hole in the center. An annular boss in the middle of the through hole divides the through hole into two bearing mounting holes (41). A left angular contact bearing (42) and a right angular contact bearing (43) are respectively provided in the bearing mounting holes (41). The left angular contact bearing (42) and the right angular contact bearing (43) are both sleeved on the first cylindrical surface (33). A bushing or washer is provided between the inner ring of the left angular contact bearing (42) and the inner ring of the angular contact bearing (13) on the first joint support plate (11). The knee joint output spool (5) has a mounting hole in the center. One side of the mounting hole is interference-fitted with the second cylindrical surface (34). The other side of the mounting hole is provided with a limiting separation ring. The inner ring of the right angular contact bearing (43) is set close to the limiting separation ring.

10. The robotic knee joint based on tendon motion control according to any one of claims 1-5, 7 or 9, characterized in that: A cable end locking hole (51) is provided on the knee joint output cable reel (5), and a cable end locking seat (26) is provided on the knee joint support housing (22). The cable end locking hole (51) and the cable end locking seat (26) respectively fix the two ends of the control cable.

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