Rope-driven anthropomorphic wrist joint with spin decoupling property

Abstract

The application discloses a rope-driven humanoid wrist joint with self-rotation decoupling characteristics and belongs to the technical field of robots.The wrist joint comprises a self-rotation decoupling mechanism and a differential mechanism; a fixed wheel in the self-rotation decoupling mechanism is fixed with a robot forearm; a driving wheel is connected with the differential mechanism; and a rope group realizes flexible driving of a joint module.The self-rotation decoupling mechanism adopts a movable pulley group structure, utilizes the movable pulley characteristics to realize motion decoupling of two groups of steel wire ropes when passing through the self-rotation joint, and enables the driving unit to be concentratedly arranged on a robot base or a proximal end structure; the differential mechanism adopts a differential self-rotation shaft, a fixed seat outside the differential self-rotation shaft and two groups of differential rotating wheels symmetrically arranged to form a differential structure, can realize multi-degree-of-freedom compound motions such as pitching and yawing in a limited space, and significantly improves the compactness of the structure.The application adopts a structure form of rope driving combined with rope transmission, enhances the flexibility of the joint, and effectively isolates the impact and vibration of the motor output end.

Description

Technical Field

[0001] This invention belongs to the field of robotics technology, specifically relating to a cable-driven anthropomorphic wrist joint with self-rotation decoupling characteristics. Background Technology

[0002] Humanoid robot wrist joints need to achieve three degrees of freedom of movement simultaneously within a confined forearm space, and the drive source is moved to the base to reduce end-effector inertia. Chinese Patent 202010620017.2 discloses a three-degree-of-freedom wrist joint structure for a rope-driven robotic arm, proposing a rope-driven wrist joint scheme with three motors, a base arrangement, and multiple ropes in parallel: three motors are fixed to the base, and after being turned by multiple stages of fixed pulleys, they drive the rotating base, rocker arm, and end-effector platform respectively with closed steel wire ropes, achieving preliminary weight reduction.

[0003] However, the structure of the aforementioned three-degree-of-freedom chord-driven wrist joint inherently has the following shortcomings: Firstly, there is the issue of motion coupling: the wire rope is dragged during the rolling process. When the slewing base rotates, the wire rope segments of the drive rocker and the end platform rotate with the base, causing additional changes in the pitch / yaw rope length. The controller must compensate for this coupled displacement in real time, but it is still impossible to completely decouple them.

[0004] Secondly, there is the issue of space redundancy: this solution occupies a large amount of assembly space, which limits the requirements of the humanoid robot for the appearance and internal integration of the thin forearm. Summary of the Invention

[0005] This invention is proposed to solve the problems existing in the prior art, and its purpose is to provide a rope-driven anthropomorphic wrist joint with self-rotation decoupling characteristics.

[0006] The technical solution of this invention is: a rope-driven anthropomorphic wrist joint with rotation decoupling characteristics, comprising a rotation decoupling mechanism and a differential mechanism. The rotation decoupling mechanism includes a fixed wheel, a follower wheel, a driving wheel, and a rope assembly. The fixed wheel is fixed to the robot forearm, and the driving wheel is connected to the differential mechanism. The fixed wheel, follower wheel, and driving wheel form a movable pulley group structure through the rope assembly, realizing the motion decoupling of the two sets of steel wire ropes when passing through the rotation joint. The differential mechanism includes a differential rotation shaft, a differential rotation shaft outer fixed seat, and a differential rotating wheel. The differential rotation shaft is rotatably supported on the differential rotation shaft outer fixed seat. Two sets of rotating differential rotating wheels are symmetrically arranged on both sides of the differential rotation shaft outer fixed seat, realizing the composite motion of pitch and yaw through the differential structure. The rope assembly realizes flexible drive for the first joint module and the second joint module.

[0007] Furthermore, the fixed wheel has a multi-step end on the side facing the follower wheel, with its first step shoulder rotatably connected to the follower wheel via a first bearing, and its second step shoulder, axially away from the follower wheel, rotatably connected to the driving wheel via a second bearing.

[0008] Furthermore, the outer ring of the follower wheel is symmetrically formed with two stepped surfaces, and cylindrical grooves are formed on the stepped surfaces for wiring. The outer ring of the follower wheel has a fan-shaped groove, and two stepped shafts extend from the bottom plane of the groove. The two stepped shafts are equipped with a first guide wheel and a second guide wheel of the follower wheel. Similarly, the inner ring of the follower wheel has a cylindrical groove for wiring, and an inner fan-shaped groove. A stepped shaft extends from the bottom plane of the inner fan-shaped groove, and a third guide wheel of the follower wheel is provided on the stepped shaft.

[0009] Furthermore, the fixed wheel is provided with a fixed wheel fixed rope end, the driving wheel is provided with a driving wheel fixed rope end, one end of the first wire rope A and the first wire rope B are connected to the fixed wheel fixed rope end, and the other end is guided by the follower wheel first guide wheel and then connected to the driving wheel fixed rope end.

[0010] Furthermore, after being guided by the first left guide wheel and the first right guide wheel of the fixed wheel, the second wire rope A and the second wire rope B are symmetrically wound around the cylindrical groove on the outer ring of the follower wheel. After being guided by the second guide wheel of the follower wheel, they are wound in the opposite direction around the cylindrical groove on the outer ring of the follower wheel. After being guided by the first left guide wheel and the first right guide wheel of the driving wheel, they are led out from the self-rotation decoupling mechanism.

[0011] Furthermore, after being guided by the second left guide wheel and the second right guide wheel of the fixed wheel, the third wire rope A and the third wire rope B symmetrically wind around the cylindrical groove of the inner ring of the follower wheel. After being guided by the third guide wheel of the follower wheel, they wind in the opposite direction around the cylindrical groove of the inner ring of the follower wheel. After passing the second left guide wheel and the second right guide wheel of the driving wheel, they are led out from the self-rotation decoupling mechanism.

[0012] Furthermore, L-shaped brackets extend symmetrically from both sides of the circular facade of the fixed wheel. A first self-rotating guide wheel is provided in the L-shaped bracket. After being guided by the first self-rotating guide wheel, the fourth steel wire rope A and the fourth steel wire rope B cross and wrap around the cylindrical facade of the driving wheel, and are connected to the opening fixed rope ends on both sides of the facade of the driving wheel.

[0013] Furthermore, the protruding end of the differential rotation shaft is connected to the hand.

[0014] Furthermore, after the second wire rope A and the second wire rope B, the third wire rope A and the third wire rope B are led out from the self-rotation decoupling mechanism, they are cross-wound onto the two sets of differential rotating wheels and connected to the opening fixed rope end of the differential rotating wheel.

[0015] Furthermore, there are four fifth steel wire ropes. One end of the fifth steel wire rope is connected to the differential rotating wheel, and the other end is guided by the second rotation guide wheel on the outer fixed seat of the differential rotation shaft, and then crosses around to the hole fixed rope end on the second stepped shaft of the differential rotation shaft.

[0016] The beneficial effects of this invention are as follows: This invention effectively decouples the motion of two sets of steel wire ropes when passing through the self-rotating joint by employing a set of movable pulley mechanisms, allowing the drive unit to be centrally arranged on the robot base or near-end structure.

[0017] In this invention, the joint adopts a differential structure, which can realize multi-degree-of-freedom compound movements such as pitch and yaw of the hand within a limited space. At the same time, the outputs of the two actuators are combined to optimize the force-sealing characteristics of the transmission structure, significantly improving the compactness of the structure and the output torque. This allows the robot wrist joint to occupy a smaller space while having a larger working space, which is conducive to improving the overall integration and environmental adaptability of the humanoid robot.

[0018] This invention adopts a structure combining rope drive and rope transmission, which enhances the flexibility of the joints and effectively isolates the impact and vibration at the motor output. Compared with the direct drive method, this structure can absorb some energy through the elastic deformation of the rope when the robot is involved in an accidental collision or overload, reducing the risk of damage to the joint body and the external environment, thereby significantly improving the safety of humanoid robots in human-robot interaction. Attached Figure Description

[0019] Figure 1 This is a structural diagram of the rope-driven, humanoid wrist joint of the present invention; Figure 2 This is a structural diagram of the rope-driven, humanoid wrist joint of the present invention; Figure 3 This is a front view of the rope-driven, humanoid wrist joint of the present invention; Figure 4 This is a cross-sectional view of the rope-driven, humanoid wrist joint of the present invention; Figure 5 This is an exploded view of the self-rotation decoupling mechanism of the rope-driven humanoid wrist joint of the present invention; Figure 6 This is a perspective view of the self-rotation decoupling mechanism of the rope-driven humanoid wrist joint of the present invention. Figure 7 This is another perspective view of the self-rotation decoupling mechanism of the rope-driven humanoid wrist joint of the present invention. Figure 8 This is an exploded view of the differential mechanism of the rope-driven humanoid wrist joint of the present invention; The components include: 1. Rotation decoupling mechanism; 2. Differential mechanism; 3. Hand; 4. First joint module; 5. Second joint module; 10. Robot forearm; 11. Second left guide wheel of fixed wheel; 12. First guide wheel of follower wheel; 13. Second right guide wheel of fixed wheel; 14. Second guide wheel of follower wheel; 15. Fixed wheel; 16. Follower wheel; 17. Driving wheel; 18. First left guide wheel of driving wheel; 19. First right guide wheel of driving wheel; 110. First rotation guide wheel; 111. Third guide wheel of follower wheel; 112. Fixed wheel fixed rope end; 113. First left guide wheel of fixed wheel; 114. First right guide wheel of fixed wheel; 115. Second left guide wheel of driving wheel; 116. Second right guide wheel of driving wheel; 117. First absolute encoder mounting base; 118. First absolute encoder. Rotating side of the encoder; 119, First absolute encoder magnetic base; 120, Drive wheel fixed rope end; 121, First wire rope A; 122, First wire rope B; 21, First differential deflection base; 22, Bearing end cover; 23, Differential rotation shaft; 24, Differential rotation shaft outer fixed seat; 25, Differential rotation shaft bushing; 26, Second differential deflection base; 27, Differential rotating wheel; 28, Second rotation guide wheel; 29, Third absolute encoder; 210, Second absolute encoder mounting base; 211, Second absolute encoder magnetic base; 212, Rotating side of the second absolute encoder; 213, Fifth wire rope; 40, Bowden conduit; 41, Third wire rope A; 42, Third wire rope B; 43, Second wire rope A; 44, Second wire rope B; 51, Fourth wire rope A; 52, Fourth wire rope B. Detailed Implementation

[0020] The present invention will now be described in detail with reference to the accompanying drawings and embodiments: like Figures 1 to 8As shown, a rope-driven anthropomorphic wrist joint with rotation decoupling characteristics includes a rotation decoupling mechanism 1 and a differential mechanism 2. The rotation decoupling mechanism 1 includes a fixed pulley 15, a follower pulley 16, a drive pulley 17, and a rope assembly. The fixed pulley 15 is fixed to the robot forearm 10, and the drive pulley 17 is connected to the differential mechanism 2. The fixed pulley 15, follower pulley 16, and drive pulley 17 form a movable pulley group structure through the rope assembly, realizing two sets of wire ropes (wherein, one set of wire ropes includes a second wire rope A43 and a second wire rope B44, and the other set of wire ropes includes...). The motion decoupling of the third wire rope (A41 and B42) when passing through the rotation decoupling mechanism; the differential mechanism 2 includes a differential rotation shaft 23, a differential rotation shaft outer fixed seat 24, and a differential rotating wheel 27. The differential rotation shaft 23 is rotatably supported on the differential rotation shaft outer fixed seat 24. Two sets of rotating differential rotating wheels 27 are symmetrically arranged on both sides of the differential rotation shaft outer fixed seat 24. The differential structure realizes the composite motion of pitch and yaw; the rope group realizes the flexible drive of the first joint module 4 and the second joint module 5.

[0021] The fixed wheel 15 has a multi-step end on the side facing the follower wheel 16. Its first step shoulder is rotatably connected to the follower wheel 16 through a first bearing, and its second step shoulder, which is axially away from the follower wheel 16, is rotatably connected to the driving wheel 17 through a second bearing.

[0022] The outer ring of the follower wheel 16 is symmetrically formed with two stepped surfaces. Cylindrical grooves are formed on the stepped surfaces for wiring. The outer ring of the follower wheel 16 has a fan-shaped groove. Two stepped shafts extend from the bottom plane of the groove. The two stepped shafts are provided with the first guide wheel 12 and the second guide wheel 14 of the follower wheel. Similarly, the inner ring of the follower wheel 16 has a cylindrical groove for wiring. The inner ring of the follower wheel 16 has an inner fan-shaped groove. A stepped shaft extends from the bottom plane of the inner fan-shaped groove. The stepped shaft is provided with the third guide wheel 111 of the follower wheel.

[0023] The fixed wheel 15 is provided with a fixed wheel fixed rope end 112, and the driving wheel 17 is provided with a driving wheel fixed rope end 120. One end of the first wire rope A121 and the first wire rope B122 are connected to the fixed wheel fixed rope end 112, and the other end is guided by the follower wheel first guide wheel 12 and then connected to the driving wheel fixed rope end 120.

[0024] After being guided by the first left guide wheel 113 and the first right guide wheel 114 on the fixed wheel 15, the second wire rope A43 and the second wire rope B44 are symmetrically wound around the cylindrical groove on the outer ring of the follower wheel 16. After being guided by the second guide wheel 14 of the follower wheel, they are wound in the opposite direction around the cylindrical groove on the outer ring of the follower wheel 16. After passing through the first left guide wheel 18 and the first right guide wheel 19 of the driving wheel, they are led out from the self-rotation decoupling mechanism 1.

[0025] After being guided by the second left guide wheel 11 and the second right guide wheel 13 on the fixed wheel 15, the third wire rope A41 and the third wire rope B42 are symmetrically wound onto the cylindrical groove of the inner ring of the follower wheel 16. After being guided by the third guide wheel 111 of the follower wheel, they are wound in the opposite direction onto the cylindrical groove of the inner ring of the follower wheel 16. After passing the second left guide wheel 115 and the second right guide wheel 116 of the driving wheel, they are led out from the self-rotation decoupling mechanism 1.

[0026] The fixed wheel 15 has L-shaped brackets extending symmetrically from both sides of its circular facade. The L-shaped brackets are equipped with a first self-rotating guide wheel 110. After being guided by the first self-rotating guide wheel 110, the fourth steel wire rope A51 and the fourth steel wire rope B52 cross and wrap around the cylindrical facade of the driving wheel 17, and are connected to the openings on both sides of the facade of the driving wheel 17 to fix the rope ends.

[0027] The protruding end of the differential rotation shaft 23 is connected to the hand part 3.

[0028] After the second wire rope A43 and the second wire rope B44, the third wire rope A41 and the third wire rope B42 are led out from the self-rotation decoupling mechanism 1, they are cross-wound onto the two sets of differential rotating wheels 27 and connected to the opening fixed rope end of the differential rotating wheel 27.

[0029] The fifth wire rope 213 consists of four strands. One end of the fifth wire rope 213 is connected to the differential rotating wheel 27, and the other end is guided by the second rotation guide wheel 28 on the outer fixed seat 24 of the differential rotation shaft, and then crosses around to the hole-fixed rope end on the second stepped shaft of the differential rotation shaft 23.

[0030] There are four fifth steel wire ropes 213. One end of the fifth steel wire rope 213 is connected to the differential rotating wheel 27, and the other end is guided by the second rotation guide wheel 28 on the outer fixed seat 24 of the differential rotation shaft, and then crosses around to the hole fixed rope end on the second stepped shaft of the differential rotation shaft 23.

[0031] Specifically, the second wire rope A43, the second wire rope B44, the third wire rope A41, and the third wire rope B42 are used to jointly drive the deflection and rotation of the differential mechanism 2, thereby realizing the movement of the second and third degrees of freedom of the wrist joint.

[0032] Specifically, the self-rotation decoupling mechanism 1 consists of a fixed wheel 15, a first left guide wheel 113, a first right guide wheel 114, a second left guide wheel 11, a second right guide wheel 13, a fixed rope end 112, a follower wheel 16, a first guide wheel 12, a second guide wheel 14, a third guide wheel 111, a driving wheel 17, a first left guide wheel 18, a first right guide wheel 19, a second left guide wheel 115, a second right guide wheel 116, a fixed rope end 120, a first self-rotating guide wheel 110, a first absolute encoder mounting base 117, a first absolute encoder rotating side 118, a first absolute encoder magnetic base 119, a first wire rope A 121, a first wire rope B 122, a fourth wire rope A 51, and a fourth wire rope B 52.

[0033] Specifically, the fixed wheel 15 serves as the connecting base. The annular boss end of the fixed wheel 15 is fixedly connected to the humanoid robot forearm 10 by bolts. The first left guide wheel 113 and the first right guide wheel 114 are symmetrically installed on one side of the annular boss end of the fixed wheel 15, and the second left guide wheel 11 and the second right guide wheel 13 are symmetrically installed on the other side. The two fixed wheel fixing rope ends 112 are installed between the first left guide wheel 113 and the first right guide wheel 114. The two circular surfaces of the fixed wheel 15 have L-shaped brackets symmetrically extending out, and the first self-rotating guide wheel 110 is fixed by the shaft shoulder and the open retaining ring.

[0034] Specifically, the other end of the fixed wheel 15 is a multi-step shaft end. The first step shaft shoulder and the shaft are fixed to the axial movement of the inner ring of the first bearing by a retaining circlip. The outer ring of the bearing is fixed to the follower wheel 16 by a retaining circlip through a hole. The outer ring of the follower wheel 16 has two symmetrically designed stepped surfaces. Cylindrical grooves are opened on the stepped surfaces for wiring. The outer ring of the follower wheel 16 has a fan-shaped groove. Two stepped shafts extend from the bottom plane of the groove to fix the first guide wheel 12 and the second guide wheel 14 of the follower wheel with different diameters, respectively. Similarly, the inner ring of the follower wheel 16 has a cylindrical groove for wiring. The inner ring of the follower wheel has an inner fan-shaped groove. Stepped shafts extend from the bottom plane of the inner fan-shaped groove to fix the third guide wheel 111 of the follower wheel.

[0035] In terms of position, the semi-circular guide grooves of the first left guide wheel 113 and the first right guide wheel 114 of the fixed wheel are tangent to the semi-cylindrical guide groove of the outer ring of the follower wheel 16. Similarly, the semi-circular guide grooves of the second left guide wheel 11 and the second right guide wheel 13 of the fixed wheel are tangent to the semi-cylindrical guide groove of the inner ring of the follower wheel 16.

[0036] Specifically, the second stepped shaft shoulder of the fixed wheel 15 is fixed to the axial movement of the inner ring of the second bearing with a snap ring, and the outer ring of the bearing is fixed to the driving wheel 17 through a hole with a snap ring. The first left guide wheel 18 and the first right guide wheel 19 of the driving wheel are symmetrically installed on one side of the annular groove of the driving wheel 17, and the second left guide wheel 115 and the second right guide wheel 116 of the driving wheel are symmetrically installed on the other side.

[0037] In terms of position, the semi-circular guide grooves of the first left guide wheel 18 and the first right guide wheel 19 of the driving wheel are tangent to the semi-cylindrical guide groove of the outer ring of the follower wheel 16. Similarly, the semi-circular guide grooves of the second left guide wheel 115 and the second right guide wheel 116 of the driving wheel are tangent to the semi-cylindrical guide groove of the inner ring of the follower wheel 16.

[0038] The two drive wheels are fixed with rope ends 120 installed between the first left guide wheel 18 and the first right guide wheel 19 of the drive wheel. The drive wheel 17 has four cylindrical platforms extending from its annular groove, with threaded holes at its upper ends for fixed connection with the differential mechanism 2.

[0039] Specifically, the rope winding method of the self-rotation decoupling mechanism 1 is as follows: One end of each of the two first wire ropes A121 and B122 is symmetrically fixed to the fixed rope end 112 of the fixed wheel, then passes around the cylindrical groove on the outer stepped surface of the follower wheel 16, and is further guided by the first guide wheel 12 of the follower wheel before passing around the cylindrical groove on the outer stepped surface of the follower wheel 16. The other ends of the ropes are then symmetrically fixed to the fixed rope end 120 of the driving wheel.

[0040] One end of each of the two second steel wire ropes A43 and B44 is transmitted through the Bowden conduit 40 to the wire threading end of the Bowden conduit 40 on the fixed end of the robot forearm 10. After being guided by the first left guide wheel 113 and the first right guide wheel 114 of the fixed wheel, they are symmetrically wound around the cylindrical groove on the outer ring of the follower wheel 16. After being guided by the second guide wheel 14 of the follower wheel, they are further wound around the cylindrical groove on the outer ring of the follower wheel 16. After being guided by the first left guide wheel 18 and the first right guide wheel 19 of the drive wheel, they reach the other end of the rope.

[0041] One end of each of the two third steel wire ropes A41 and B42 is transmitted through the Bowden conduit 40 to the wire-passing end of the Bowden conduit 40 on the fixed end of the robot forearm 10. After being guided by the second left guide wheel 11 and the second right guide wheel 13 of the fixed wheel, they are symmetrically wound around the cylindrical groove of the inner ring of the follower wheel 16. After being guided by the third guide wheel 111 of the follower wheel, they are further wound around the cylindrical groove of the inner ring of the follower wheel 16. After being guided by the second left guide wheel 115 and the second right guide wheel 116 of the drive wheel, they reach the other end of the rope.

[0042] One end of each of the two fourth steel wire ropes A51 and B52 is transmitted through the Bowden conduit 40 to the wire threading end of the Bowden conduit 40 on the fixed end of the robot arm 10. After passing through the first self-rotating guide wheel 110, they cross and are wound upward / downward onto the cylindrical surface of the drive wheel 17, and the rope ends are fixed through the openings on both sides of the surface of the drive wheel 17.

[0043] The rotation decoupling principle of the rotation decoupling mechanism 1 is as follows: One end of the first wire rope A121 and the first wire rope B122 is fixed to the fixed end 112 of the fixed wheel, and after passing through the first guide wheel 12 of the follower wheel, the other end is fixed to the fixed end 120 of the driving wheel. Thus, through the connection of the first wire rope A121 and the first wire rope B122, the fixed wheel 15, the follower wheel 16, and the driving wheel 17 form a standard set of movable pulleys.

[0044] To keep the fixed end 112 of the fixed wheel fixed, assume that the driving wheel 17 is driven by the fourth wire rope A 51 and the fourth wire rope B 52 at a speed of r1* ω If the speed rotates clockwise or counterclockwise, it will drive the second wire rope A 43 and the second wire rope B 44 to generate r2*. ω The change in rope length *Δt will cause the third wire rope A41 and the third wire rope B42 to generate r3*. ω *Δt represents the change in rope length; under the influence of the characteristics of the movable pulley, the follower pulley 16 moves at a speed of r. n * ω / 2( n =1,2,3) rotate in the same direction at speeds in the same direction; the ropes on both sides of the first guide wheel 12, the second guide wheel 14, and the third guide wheel 111 shorten in the same direction of rotation, with a shortening amount of 2*r. n * ω / 2*Δt = r n * ω *Δt ( n=1,2,3), which cancels out the changes in rope length of the second wire rope A 43, the second wire rope B44, the third wire rope A41, and the third wire rope B 42 caused by the rotation of the drive wheel 17. Furthermore, while the drive wheel 17 rotates, the output ends of the second wire rope A 43, the second wire rope B44, the third wire rope A41, and the third wire rope B42 remain unchanged.

[0045] Specifically, the first absolute encoder mounting base 117 extends out four legs and is fixedly connected to the drive wheel 17. The rotating side 118 of the first absolute encoder is fixedly connected to the top of the third step of the multi-step shaft of the fixed wheel 15 through a set screw. The magnetic base 119 of the first absolute encoder is inserted into the first absolute encoder mounting base 117 and fixedly connected by bolts.

[0046] A 0.8mm gap is left between the rotating side 118 of the first absolute encoder and the magnetic base 119 of the first absolute encoder. This electrical component is used to measure the rotation angle of the self-rotating decoupling mechanism 1 in real time.

[0047] Specifically, the differential mechanism 2 consists of a differential rotation shaft 23, a differential rotation shaft sleeve 25, a differential rotation shaft outer fixing seat 24, a first differential deflection base 21, a second differential deflection base 26, a differential rotating wheel 27, a second rotation guide wheel 28, a bearing end cover 22, a second absolute encoder mounting seat 210, a second absolute encoder magnetic seat 211, a second absolute encoder rotating side 212, and a third absolute encoder 29.

[0048] One side of the differential rotation shaft 23 is fixed to the hand part 3 by bolts, and the other side is sequentially equipped with a first deep groove ball bearing, a differential rotation shaft sleeve 25, and a second deep groove ball bearing. The outer fixing seat 24 of the differential rotation shaft has a groove, and the outer side of the bearing is fitted into the groove by the two outer fixing seats 24 of the differential rotation shaft. After the two outer fixing seats 24 of the differential rotation shaft are fitted together, a multi-step shaft is formed on the left and right sides. The axial movement of the inner side of the third deep groove ball bearing is fixed on the stepped shaft on both sides by the first stepped shaft shoulder and the shaft retainer. The outer side of the third deep groove ball bearing is fixed to the differential rotating wheel 27 by the hole retainer. Further, the axial movement of the inner side of the fourth deep groove ball bearing is fixed by the second stepped shaft shoulder and the shaft retainer. The outer side of the fourth deep groove ball bearing is fixed to the first differential deflection base 21 and the second differential deflection base 26 by the bearing end cover 22.

[0049] The second absolute encoder mounting base 210 extends out four legs and is fixedly connected to the outer fixed base 24 of the differential rotation shaft. The rotating side 212 of the second absolute encoder is interference-fitted with the top of the differential rotation shaft 23. The magnetic base 211 of the second absolute encoder is inserted into the second absolute encoder mounting base 210 and fixedly connected by bolts.

[0050] A 0.8mm gap is left between the rotating side 212 of the second absolute encoder and the magnetic base 211 of the second absolute encoder. This electrical component is used to measure the rotation angle of the differential mechanism 2 in real time.

[0051] The third absolute encoder 29 is fixed to the inside of the multi-step shaft formed on the left and right sides after the outer fixing seats 24 of the two differential rotation shafts are closed together by its own shaft shoulder. The groove on its rotating side is fitted with the corresponding boss on the bearing end cover 22. This electrical component is used to measure the deflection rotation angle in the differential mechanism 2 in real time.

[0052] Specifically, the rope winding method of differential mechanism 2 is as follows: The two second steel wire ropes A43 and B44, and the two third steel wire ropes A41 and B42, after passing through the rotation decoupling mechanism 1, are respectively crossed and wound around the two differential rotating wheels 27, and the rope ends are fixed through the openings on both sides of the differential rotating wheels 27. There are four fifth steel wire ropes 213, one end of which is connected to both sides of the two differential rotating wheels 27, and the other end is guided by the second rotation guide wheel 28 on the outer fixing seat 24 of the differential rotation shaft, and then crossed and wound around the opening on the second stepped shaft of the differential rotation shaft 23 to fix the rope end.

[0053] The motion produced by the power output of the wrist joint is as follows: When the second steel wire rope A43, the second steel wire rope B44 and the third steel wire rope A41, the third steel wire rope B42 driven by the first joint module 4 pass through the self-rotation decoupling mechanism 1 and are wound onto the differential mechanism 2, when the third steel wire rope A41, the second steel wire rope B44 or the second steel wire rope A43 and the third steel wire rope B42 are pulled in the same direction and at the same speed, the second degree of freedom of the wrist joint produces a deflection motion, but no self-rotation motion; When the second steel wire rope A43, the second steel wire rope B44, and the third steel wire rope A41 and the third steel wire rope B42 driven by the first joint module 4 pass through the self-rotation decoupling mechanism 1 and are wound onto the differential mechanism 2, when the third steel wire rope A41, the second steel wire rope B44 or the second steel wire rope A43 and the third steel wire rope B42 are pulled in the opposite direction at the same speed, the third degree of freedom of the wrist joint generates a self-rotation motion without deflection motion; When the second steel wire rope A43, the second steel wire rope B44, and the third steel wire rope A41 and the third steel wire rope B42 driven by the first joint module 4 pass through the rotation decoupling mechanism 1 and are wound onto the differential mechanism 2, when the third steel wire rope A41, the second steel wire rope B44 or the second steel wire rope A43 and the third steel wire rope B42 are pulled at different speeds, the second and third degrees of freedom of the wrist joint will operate and couple to generate deflection motion and rotation motion.

[0054] More specifically, the three degrees of freedom of movement corresponding to the human wrist joint are: When the fourth steel wire rope A51 or the fourth steel wire rope B52 driven by the second joint module 5 is pulled, the drive wheel 17 will generate a counterclockwise or clockwise rotation of the first degree of freedom of the wrist joint, and drive the differential mechanism 2 and the hand 3 to rotate synchronously to simulate the rotation of the human wrist. When the third steel wire rope A41 and the second steel wire rope B44 or the second steel wire rope A43 and the third steel wire rope B42 driven by the first joint module 4 are pulled in the same direction and at the same speed, the second degree of freedom of the wrist joint produces a deflection motion to simulate the pitching and flexing motion of the human wrist. When the third steel wire rope A41 and the second steel wire rope B44, or the second steel wire rope A43 and the third steel wire rope B42 driven by the first joint module 4 are pulled in the opposite direction at the same speed, the wrist joint's third degree of freedom generates a rotational motion that first rotates 90°. Subsequently, when the third steel wire rope A41 and the second steel wire rope B44, or the second steel wire rope A43 and the third steel wire rope B42 driven by the first joint module 4 are pulled in the same direction at the same speed, the wrist joint's second degree of freedom generates a yaw motion, which simulates the yaw motion of the human wrist.

[0055] Tensioning solutions for the rope end fixed to the wrist joint include, but are not limited to, bolt-slider tensioning solutions, tension / compression spring tensioning solutions, disc spring tensioning solutions, and temperature-controlled spring tensioning solutions.

[0056] This invention effectively decouples the motion of two sets of steel wire ropes when passing through the self-rotating joint by employing a set of movable pulley mechanisms, allowing the drive unit to be centrally arranged on the robot base or near-end structure.

[0057] In this invention, the joint adopts a differential structure, which can realize multi-degree-of-freedom compound motion such as pitch and yaw within a limited space, significantly improving the compactness of the structure. This allows the robot wrist joint to occupy a smaller space while having a larger working space, which is conducive to improving the overall integration and environmental adaptability of the humanoid robot.

[0058] This invention adopts a structure combining rope drive and rope transmission, which enhances the flexibility of the joints and effectively isolates the impact and vibration at the motor output. Compared with the direct drive method, this structure can absorb some energy through the elastic deformation of the rope when the robot is involved in an accidental collision or overload, reducing the risk of damage to the joint body and the external environment, thereby significantly improving the safety of humanoid robots in human-robot interaction.

Claims

1. A cable-driven anthropomorphic wrist joint with self-rotation decoupling characteristics, characterized in that: It includes a rotation decoupling mechanism (1) and a differential mechanism (2), which are integrated into the wrist joint and form a compact three-degree-of-freedom drive structure; The self-rotation decoupling mechanism (1) includes a fixed wheel (15), a follower wheel (16), a driving wheel (17), and a rope group. The fixed wheel (15) is fixed to the robot forearm (10), and the driving wheel (17) is connected to the differential mechanism (2). The fixed wheel (15), the follower wheel (16), and the driving wheel (17) form a movable pulley group structure through the rope group to realize the motion decoupling of the two sets of wire ropes when passing through the self-rotation decoupling mechanism. The fixed wheel (15) forms a multi-step end on the side facing the follower wheel (16), and its first step shoulder is rotatably connected to the follower wheel (16) through a first bearing, and its second step shoulder, which is axially away from the follower wheel (16), is rotatably connected to the driving wheel (17) through a second bearing. The outer ring of the follower wheel (16) is symmetrically formed with two stepped surfaces. The stepped surfaces have cylindrical grooves for wire routing. The outer ring of the follower wheel (16) has a fan-shaped groove. Two stepped shafts extend from the bottom plane of the fan-shaped groove. The two stepped shafts are provided with the first guide wheel (12) and the second guide wheel (14) of the follower wheel. Similarly, the inner ring of the follower wheel (16) has a cylindrical groove for wire routing. The inner ring of the follower wheel (16) has an inner fan-shaped groove. A stepped shaft extends from the bottom plane of the inner fan-shaped groove. The stepped shaft is provided with the third guide wheel (111) of the follower wheel. The rope group includes the first wire rope A (121) and the first wire rope B (122). The fixed wheel (15) is provided with a fixed wheel fixed rope end (112), and the driving wheel (17) is provided with a driving wheel fixed rope end (120). One end of the first wire rope A (121) and the first wire rope B (122) are connected to the fixed wheel fixed rope end (112), and the other end is guided by the follower wheel first guide wheel (12) and then connected to the driving wheel fixed rope end (120). The differential mechanism (2) includes a differential rotation shaft (23), a differential rotation shaft outer fixed seat (24), and a differential rotating wheel (27). The differential rotation shaft (23) is rotatably supported on the differential rotation shaft outer fixed seat (24). Two sets of rotating differential rotating wheels (27) are symmetrically arranged on both sides of the differential rotation shaft outer fixed seat (24). The differential rotation of the differential rotating wheels (27) realizes the combined motion of pitch and yaw.

2. The cable-driven anthropomorphic wrist joint with self-rotation decoupling characteristics according to claim 1, characterized in that: A set of wire ropes includes a second wire rope A (43) and a second wire rope B (44). The second wire rope A (43) and the second wire rope B (44) are guided by the first left guide wheel (113) and the first right guide wheel (114) of the fixed wheel (15), and then symmetrically wound around the cylindrical groove of the outer ring of the follower wheel (16). After being guided by the second guide wheel (14) of the follower wheel, they are wound in the opposite direction around the cylindrical groove of the outer ring of the follower wheel (16). After being guided by the first left guide wheel (18) and the first right guide wheel (19) of the driving wheel, they are led out from the self-rotation decoupling mechanism (1).

3. The cable-driven anthropomorphic wrist joint with self-rotation decoupling characteristics according to claim 1, characterized in that: Another set of wire ropes includes a third wire rope A (41) and a third wire rope B (42). After being guided by the second left guide wheel (11) and the second right guide wheel (13) on the fixed wheel (15), the third wire rope A (41) and the third wire rope B (42) are symmetrically wound around the cylindrical groove of the inner ring of the follower wheel (16). After being guided by the third guide wheel (111) of the follower wheel respectively, they are wound in the opposite direction around the cylindrical groove of the inner ring of the follower wheel (16). After passing the second left guide wheel (115) and the second right guide wheel (116) of the driving wheel, they are led out from the self-rotation decoupling mechanism (1).

4. The cable-driven anthropomorphic wrist joint with self-rotation decoupling characteristics according to claim 1, characterized in that: The fixed wheel (15) has L-shaped brackets extending symmetrically from both sides of its circular facade. The L-shaped brackets are equipped with a first self-rotating guide wheel (110). After being guided by the first self-rotating guide wheel (110), the fourth wire rope A (51) and the fourth wire rope B (52) cross and wrap around the cylindrical facade of the driving wheel (17), and are connected to the openings on both sides of the facade of the driving wheel (17) to fix the rope ends.

5. The cable-driven anthropomorphic wrist joint with self-rotation decoupling characteristics according to claim 1, characterized in that: The protruding end of the differential rotation shaft (23) is connected to the hand (3).

6. The cable-driven anthropomorphic wrist joint with rotation decoupling characteristics according to claim 2 or 3, characterized in that: After the second wire rope A (43), the second wire rope B (44), the third wire rope A (41), and the third wire rope B (42) are led out from the self-rotation decoupling mechanism (1), they are cross-wound onto the two sets of differential rotating wheels (27) and connected to the opening fixed rope end of the differential rotating wheel (27).

7. The cable-driven anthropomorphic wrist joint with self-rotation decoupling characteristics according to claim 5, characterized in that: There are four fifth wire ropes (213). One end of the fifth wire rope (213) is connected to the differential rotating wheel (27), and the other end is guided by the second rotation guide wheel (28) on the outer fixed seat (24) of the differential rotation shaft, and then crosses around to the hole fixed rope end on the second step shaft of the differential rotation shaft (23).

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