Flexible joint mechanism of rope differential drive

Abstract

The application discloses a flexible joint structure driven by a rope differential, which comprises a pulley differential module and a connecting rod support. Two flexible drivers fixed on the joint connecting rod are respectively fixed with two rope sections, and the two rope sections are connected with differential pulleys on the pulley differential module through a plurality of idlers. When the two drivers rotate in the same direction, the two rope sections are simultaneously driven to move downward, and the pulley differential module is bent and stretched as a whole; when the two drivers rotate in the opposite direction, the two rope sections are reversely driven to move, the differential pulleys are rotated, and the rotating flanges are driven to rotate through the inner pulley. That is, the bending and stretching and the internal and external rotation of the joint are completed. Compared with the existing joint, the application has higher load bearing and smaller inertia.

Description

Technical Field

[0001] This invention relates to the field of robotics, and in particular to a flexible joint mechanism driven by cable differential. Background Technology

[0002] Humanoid robotic arms, with their high degree of similarity to humans, can play a crucial role in future society. Especially in unconstrained environments such as homes, hospitals, and public service venues, humanoid robotic arms need to ensure safe interaction with humans while completing tasks. In the development of humanoid robotic arms, the design of the joint mechanism is the most critical aspect. Currently, the design of humanoid robotic arm joints faces several significant challenges: 1. To avoid accidental injury to humans during interaction, the robotic arm needs to be lightweight and possess excellent force control capabilities; 2. Existing robotic arm joints often use a single motor to achieve one degree of freedom, which is difficult to match well with the degree of freedom of a human arm in space; 3. Humanoid robotic arms need to possess a certain load-bearing capacity and dexterity. Summary of the Invention

[0003] To address the shortcomings and improvement needs of existing technologies, this invention proposes a joint mechanism for a humanoid robotic arm. By differentially driving two degrees of freedom through two flexible actuators, the joint's load-bearing capacity is improved, and the mass distribution of the joint is redistributed, solving the problem of excessive mass in existing joints. This paper also presents a novel differential drive method based on a rope-driven pulley.

[0004] The core drive mechanism of a rope differential-driven flexible joint mechanism lies in the use of a differential drive method based on rope-driven pulleys, such as... Figure 7 As shown, the basic principle of rope differential drive is as follows: the driven pulley is fixedly connected to both ends by drive ropes, which are respectively arranged at both ends of the pulley. When the two drive ropes are pulled in the same direction and by the same distance, the pulley moves in the direction of rope movement; when the two drive ropes are pulled in opposite directions and by the same distance, the pulley rotates by a certain angle. This invention proposes a joint mechanism by extending the application of this principle.

[0005] To achieve the above objectives, the present invention provides a rope differential drive flexible joint mechanism, including a pulley differential module and an arm module connected to each other, and a connector connecting the pulley differential module and the arm module. The pulley differential module is a two-degree-of-freedom mechanism, and the arm module is a base link.

[0006] The pulley differential module includes a support bracket module, an engagement module, and a forearm connection module. The support bracket module provides installation space for the engagement module and the forearm connection module, and improves the rigidity of the entire pulley differential module. The engagement module realizes rope differential drive and outputs two degrees of freedom: flexion and extension, and rotation. The forearm connection module transmits the flexion, extension, and rotation output by the engagement module to the forearm.

[0007] The arm module includes a first flexible actuator, a second flexible actuator, an articulated arm support, and a drive pretensioning device. The first and second flexible actuators provide power for the tensioning of the first and second drive ropes, and the drive pretensioning device pretensions the first and second drive ropes at an initial moment. The articulated arm support forms the outer shell of the arm module and provides mounting support for the first flexible actuator, the second flexible actuator, and the drive pretensioning device.

[0008] Preferably, in the pulley differential module, the support bracket module is a housing, the engagement module is installed in the support bracket module, and the forearm connection module is installed in the portion of the support bracket module near the end.

[0009] Preferably, in the arm module, the articulated arm bracket is fixedly connected to the support bracket module through a connector, and the articulated arm bracket and the support bracket module can be merged into one unit. The rotation of the first flexible actuator and the second flexible actuator drives the first drive rope and the second drive rope to be stretched. The drive pretensioning device achieves the pretensioning of the first drive rope and the second drive rope by adjusting the position of the first flexible actuator and the second flexible actuator.

[0010] Preferably, the support bracket module includes a support structure and a support link, specifically including an inner fixed bracket, an inner moving bracket, an inner support link, an outer fixed bracket, an outer moving bracket, and an outer support link. The inner fixed bracket, the inner moving bracket, the outer fixed bracket, and the outer moving bracket have similar structures, and the inner support link has similar structures to the outer support link. Each support bracket is provided with a shell and a through hole structure. The interior of the shell is used to install the engagement module and the forearm connection module, and the through hole structure is used to connect the inner support link and the outer support link.

[0011] Preferably, the meshing module includes a meshing fixed end module and a meshing moving end module. The meshing fixed end module is close to the arm module, and the meshing moving end module is away from the arm module. The meshing fixed end module is connected to the meshing moving end module through the support bracket module, and the meshing fixed end module and the meshing moving end module are tangential. Figure 7 , Figure 9 , Figure 11 , Figure 12As shown, through the meshing module, the displacement and rotation of the moving pulley in the basic principle of rope differential drive are realized as two degrees of freedom: flexion / extension and rotation. Flexion / extension is specifically manifested as follows: the moving end pulley module drives the moving end meshing plate to move along a direction tangential to the fixed end meshing plate, thereby achieving the deflection of the entire moving end meshing plate relative to the fixed end meshing plate; rotation is specifically manifested as follows: the rotation of the two moving end pulley modules drives the forearm connecting flange to rotate through the forearm connecting module.

[0012] Preferably, the meshing fixed end module includes a fixed end meshing plate, a first meshing wire rope, and four fixed end idler pulleys. The four fixed end idler pulleys are installed on the fixed end meshing plate according to the holes in the fixed end meshing plate. The first meshing wire rope is fixedly connected to the mounting groove at the meshing point of the fixed end meshing plate. The four fixed end idler pulleys are used to change the connection path of the rope.

[0013] Preferably, the meshing motion end module includes a motion end meshing plate, a second meshing steel wire rope, a motion end pulley module, and a motion end idler wheel. Two motion end pulley modules are installed on the mounting holes of the motion end meshing plate, and multiple motion end idler wheels are installed on the motion end meshing plate near the inner motion support. Similarly, the second meshing steel wire rope is fixedly connected to the mounting groove at the meshing point of the motion end meshing plate. The first drive rope and the second drive rope are decoupled and fixedly connected to the motion end pulley module via the rope differential drive.

[0014] Preferably, the forearm connection module includes a forearm pulley, a forearm pulley support frame, and a forearm connection flange, wherein the forearm pulley is mounted on the forearm pulley support frame, and the forearm connection flange is fixedly connected to the forearm pulley; the first transmission rope and the second transmission rope pass through the motion end pulley module and are redirected by the motion end idler wheel, and are fixedly connected to the forearm pulley; wherein the rotation of the motion end pulley module is achieved by the forearm connection module to realize the rotation of the forearm.

[0015] Preferably, the first flexible actuator and the second flexible actuator are a SEA (Series Spring Actuator), which can measure torque by detecting the deformation of its internal spring. The first flexible actuator and the second flexible actuator are respectively connected to one end of the first drive rope and the second drive rope. The articulated arm bracket serves as the housing of the arm module and is used to install the first flexible actuator, the second flexible actuator, and the drive pretensioning device. The drive pretensioning device is used to initially pretension the first drive rope and the second drive rope.

[0016] Preferably, both the first and second flexible actuators include a servo motor, a motor bracket, a gear shaft, a torsion spring, a motor pulley, an encoder, a first helical gear, and a second helical gear. The output force is transmitted from the servo motor to the gear pair of the first and second helical gears, and then the torsion spring drives the motor pulley to rotate, thereby realizing the extension and retraction of the first and second drive ropes. The encoder is used to measure the amount of rotation of the motor pulley relative to the motor bracket caused by the presence of the torsion spring. Based on the amount of rotation and the stiffness of the torsion spring, the torque output by the first and second flexible actuators can be calculated, providing a hardware basis for force control at the control level.

[0017] Preferably, the articulated arm bracket serves as the main support part of the arm module, and has a mating plate and multiple mating holes inside, providing installation space for the first flexible actuator, the second flexible actuator, the first drive rope, and the second drive rope pretensioning device.

[0018] Preferably, the drive pretensioning device includes a first slider guide rail module, a second pulley guide rail module, and a double lead screw module. The first slider guide rail module and the second pulley guide rail module cooperate with the first flexible actuator and the second flexible actuator. The housings of the first flexible actuator and the second flexible actuator cooperate with the nuts on the double lead screw module, thereby realizing the adjustability of the front and rear positions of the first flexible actuator and the second flexible actuator. By adjusting the positions of the first flexible actuator and the second flexible actuator, the first drive rope and the second drive rope are pretensioned.

[0019] Preferably, in addition to achieving two degrees of freedom of outputting flexion and extension and rotation, the orientation of some components can be changed according to actual requirements to achieve two degrees of freedom of outputting flexion and extension and lateral swing.

[0020] The rope differential drive flexible joint mechanism provided by the present invention has the following beneficial effects:

[0021] The rope differential drive flexible joint provided by this invention is a novel two-degree-of-freedom parallel mechanism. Compared with most joints on the market, it has the characteristics of high stiffness and large load-bearing capacity. The movement of this joint can be undertaken by two motors to share the working load, and it has a high load capacity.

[0022] The mechanism provided by this invention uses a drive rope for transmission. The drive device can be positioned close to or near the platform, reducing the mass of the front-end moving parts. This design results in lightweight, high-speed, and dynamically responsive moving parts. Simultaneously, because the drive device is close to the base, system inertia is reduced, improving power performance.

[0023] This invention uses springs and ropes for transmission, which can buffer external impacts in terms of mechanical structure. The flexibility of the ropes allows the robot to provide a certain degree of cushioning and shock absorption when interacting with people or the environment, reducing the risk of collisions and damage and improving the safety of the interaction. The introduction of series elastic actuators makes the joints more compliant and enables torque feedback.

[0024] Rope-based transmission is closer to the transmission method of human tendons, and has significant advantages in terms of lightweight, flexibility, safety and adaptability, making it more suitable for use in the design and manufacture of humanoid robotic arms. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the overall structure of the present invention;

[0026] Figure 2 This is a schematic diagram of the arm module of the present invention.

[0027] Figure 3 This is a schematic diagram of the structure of the flexible actuator of the present invention;

[0028] Figure 4 This is a schematic diagram of the structure of the drive rope pretensioning device of the present invention;

[0029] Figure 5 This is a schematic diagram of the structure of the dual lead screw module of the present invention;

[0030] Figure 6 This is a schematic diagram of the arm support of the present invention;

[0031] Figure 7 This is a basic schematic diagram of the rope differential drive of the present invention;

[0032] Figure 8 This is a schematic diagram of the overall differential drive module of the present invention;

[0033] Figure 9 This is a schematic diagram of the meshing module and rope arrangement of the present invention;

[0034] Figure 10 This is a schematic diagram of the moving end engagement module of the present invention;

[0035] Figure 11 This is a partial schematic diagram of the pulley differential module of the present invention;

[0036] Figure 12 This is a diagram illustrating an extended application of the rope differential drive of the present invention;

[0037] Figure 13 This is an exploded view of the support bracket module of the present invention;

[0038] The components include: 1. Arm module; 2. Pulley differential module; 11. First flexible actuator; 12. Second flexible actuator; 13. Articulated arm support; 14. Drive pretensioning device; 15. First drive rope; 16. Second drive rope; 21. Support bracket module; 22. Engaging module; 23. Forearm connection module; 24. First transmission rope; 25. Second transmission rope; 111. Servo motor; 112. Motor bracket; 113. Gear shaft; 114. Torsion spring; 115. Motor pulley; 116. Encoder; 117. First helical gear; 118. Second helical gear; 131. Arm housing; 132. Mating plate; 133. Mating groove; 134. Mating hole; 141. Slider guide rail module; 142. Double lead screw module; 2 11. Inner fixed bracket; 212. Inner moving bracket; 213. Inner support link; 214. Outer fixed bracket; 215. Outer moving bracket; 216. Outer support link; 221. Engaging fixed end module; 222. Engaging moving end module; 231. Forearm pulley; 232. Forearm pulley support frame; 233. Forearm connecting flange; 1421. Lead screw; 1422. Lead screw nut; 1423. Lead screw support frame; 1424. Rotary wrench; 2211. Fixed end engagement plate; 2212. First engagement wire rope; 2213. Fixed end idler wheel; 2221. Moving end engagement plate; 2222. Second engagement wire rope; 2223. Moving end pulley module; 2224. Moving end idler wheel. Detailed Implementation

[0039] To make the technical problems, technical solutions and advantages of the present invention clearer, a detailed description will be given below in conjunction with the accompanying drawings and specific embodiments.

[0040] To address the existing problems, this invention provides a flexible joint mechanism driven by cable differential.

[0041] In one embodiment, refer to Figure 1-11 As shown, a rope differential driven flexible joint mechanism includes an arm module 1 and a pulley differential module 2 connected to each other, and a connector connecting the pulley differential module 2 and the arm module 1. The pulley differential module 2 is a two-degree-of-freedom mechanism that is driven by a rope, and the arm module 1 is a base connecting rod.

[0042] Specifically, such as Figure 2As shown, the arm module 1 includes a first flexible actuator 11, a second flexible actuator 12, an articulated arm support 13, and a drive pretensioning device 14. The first flexible actuator 11 and the second flexible actuator 12 are fixedly connected to the drive pretensioning device 14 and are used to adjust the front-to-back position of the first flexible actuator 11 and the second flexible actuator 12 relative to the articulated arm support 13 to pretension the drive rope. The drive pretensioning device 14 is fixedly connected to the articulated arm support 13 and can adjust the front-to-back position of the first flexible actuator 11 and the second flexible actuator 12 relative to the articulated arm support 13. Since the first drive rope 15 and the second drive rope 16 are respectively connected to the first flexible actuator 11 and the second flexible actuator 12, the drive pretensioning device can initially pretension the drive rope.

[0043] The articulated arm support 13 is fixedly connected to the support bracket module 21 via a connector. When the joint size is highly restricted, the articulated arm support 13 and the support bracket module 21 can be combined into one unit, saving space by treating the articulated arm support 13 and the support bracket 21 as a single component. The rotation of the first flexible actuator 11 and the second flexible actuator 12 causes the first drive rope 15 and the second drive rope 16 to be stretched. The drive pre-tensioning device 14 achieves pre-tensioning of the first drive rope 15 and the second drive rope 16 by adjusting the positions of the first flexible actuator 11 and the second flexible actuator 12.

[0044] The first flexible actuator 11 and the second flexible actuator 12 provide power for the stretching of the first drive rope 15 and the second drive rope 16, and the drive pretensioning device 14 pretensions the first drive rope 15 and the second drive rope 16 at the initial moment. The articulated arm bracket 13 constitutes the outer shell of the arm module 1 and provides installation support for the first flexible actuator 11, the second flexible actuator 12 and the drive pretensioning device 14.

[0045] The first flexible actuator 11 and the second flexible actuator 12 are a series spring actuator (SEA), which can measure torque by detecting the deformation of the internal spring. The first flexible actuator 11 and the second flexible actuator 12 are respectively connected to one end of the first drive rope 15 and the second drive rope 16. The articulated arm bracket 13 serves as the housing of the arm module 1 and is used to install the first flexible actuator 11, the second flexible actuator 12 and the drive rope pretensioning device 14. The drive rope pretensioning device 14 is used to initially pretension the first drive rope 15 and the second drive rope 16.

[0046] The articulated arm bracket 13 serves as the main support part of the arm module 1. It has a mating plate and multiple mating holes inside, providing installation space for the first flexible actuator 11, the second flexible actuator 12, the first drive rope 15, and the second drive rope 16 pretensioning device.

[0047] like Figure 6 As shown, the articulated arm support 13 includes an arm housing 131, a mating plate 132, and a mating hole. The mating plate 132 is located in the middle of the arm housing 131. The mating hole is located at the end of the arm housing 131. The mating plate 132 includes a mating groove 133 and a mounting hole. The mating groove 133 is located on one side of the mating plate 132. The mating groove 133 is used for mounting the drive pretensioning device 14 and providing movement space for the first flexible actuator 11 and the second flexible actuator 12. The mounting hole is located on the other side of the mating plate 132 and is fixedly connected to the drive pretensioning device 14. The arm housing 131 includes a protrusion located around the end of the arm housing. The protrusion includes several connecting holes for connecting to the pulley differential module 2. The mating hole 134 serves as a bearing hole for housing the other side of the drive pretensioning device 14. Figure 4 As shown, the drive preload device 14 includes a first slider guide rail module 141, a second pulley guide rail module, and a double lead screw module 142. Each of the first slider guide rail module 141 and the second slider guide rail module includes a slider and a guide rail, and the two guide rails are fixedly connected to the mating groove 133 of the articulated arm bracket 13.

[0048] The two sliders are fixedly connected to the bottom of the first flexible actuator 11 and the second flexible actuator 12, respectively.

[0049] The first slider guide module 141 and the second pulley guide module cooperate with the first flexible actuator 11 and the second flexible actuator 12. The housings of the first flexible actuator 11 and the second flexible actuator 12 cooperate with the nuts on the double lead screw module 142, ultimately realizing the adjustability of the front and rear positions of the first flexible actuator 11 and the second flexible actuator 12. By adjusting the positions of the first flexible actuator 11 and the second flexible actuator 12, the rope can be pre-tensioned.

[0050] like Figure 5As shown, the dual lead screw module 142 includes two lead screws 1421, two lead screw nuts 1422, a lead screw support frame 1423, and a rotary wrench 1424. One end of each lead screw 1421 is connected to the lead screw support frame 1423 via a bearing, and the other end of each lead screw 1421 is connected to the articulated arm bracket 13 via a bearing. The threaded portion of each lead screw 1421 is engaged with the lead screw nuts 1422, and the lead screw nuts 1422 are fixedly connected to the mating plates 132 at the ends of the first flexible actuator 11 and the second flexible actuator 12.

[0051] Specifically, the mating groove 133 is used for mounting and placing with the guide rail.

[0052] Specifically, the other side of the mating plate 132 is provided with a mounting hole that is fixedly connected to the lead screw support frame 1423.

[0053] Specifically, the other end of the articulated arm bracket 13 is provided with two mating holes 134 as bearing holes for placing the other side of the lead screw.

[0054] like Figure 3 As shown, both the first flexible actuator 11 and the second flexible actuator 12 include a servo motor 111, a motor bracket 112, a gear shaft 113, a torsion spring 114, a motor pulley 115, an encoder 116, a first helical gear 117, and a second helical gear 118. The motor bracket 112 is fixed to the slider in the drive preload device 14. The servo motor 111 is fixedly connected to the motor bracket 112. The gear shaft 113 is embedded in the motor bracket 112 via bearings. The end of the motor bracket 112 is fixedly connected to the lead screw nut. Furthermore, both ends of the gear shaft 113 are connected to the motor bracket via bearings. The second helical gear 118 is fixedly connected to the gear shaft 113, and the motor pulley 115 is connected via bearings. The motor shaft at the end of the servo motor is fixedly connected to the first helical gear 117, and meshes with the second helical gear 118 through the first helical gear 117. One end of the torsion spring 114 is connected to the motor pulley 115, and the other end of the torsion spring 114 is connected to the motor pulley 115. A drive rope is fixedly connected to the motor pulley 115. The force is transmitted from the motor to the gear pair of the first helical gear 117 and the second helical gear 118, and then through the torsion spring 114 to drive the motor pulley 115 to rotate, thereby realizing the extension and retraction of the drive rope. The encoder 116 is used to measure the amount of rotation of the motor pulley 115 relative to the motor bracket 112.

[0055] Specifically, the output force is transmitted from the servo motor 111 to the gear pair of the first helical gear 117 and the second helical gear 118, and then the motor pulley 115 is rotated through the torsion spring 114, thereby realizing the extension and retraction of the first drive rope 15 and the second drive rope 16; the encoder 116 is used to measure the amount of rotation of the motor pulley 115 relative to the motor bracket 112 caused by the presence of the torsion spring 114. Based on the amount of rotation and the stiffness of the torsion spring 114, the torque output by the first flexible actuator 11 and the second flexible actuator 12 can be calculated, providing a hardware basis for force control at the control level.

[0056] Combination Figure 3 and Figure 5 Specifically, the lead screw nut 1422 is fixedly connected to the end mating plate of the motor bracket 112.

[0057] Specifically, the two sliders are fixedly connected to the bottom of the motor bracket 112. For example... Figure 8 As shown, the pulley differential module 2 includes a support bracket module 21, an engagement module 22, and a forearm connection module 23 disposed therein. The support bracket module 21 is a housing, the engagement module 22 is installed in the support bracket module 21, and the forearm connection module 23 is installed in the portion of the support bracket module 21 near its end. The support bracket module 21 provides installation space for the engagement module 22 and the forearm connection module 23, and also improves the rigidity of the entire pulley differential module 2. The engagement module 22 realizes differential cable drive, outputting two degrees of freedom: flexion / extension and rotation. The forearm connection module 23 transmits the flexion / extension and rotation output by the engagement module 22 to the forearm.

[0058] The support bracket module provides installation space for the engagement module 22 and the forearm connection module 23, and improves the stiffness of the entire pulley differential module 2. The engagement module 22 implements the rope differential drive proposed in this paper, and transmits one degree of freedom in one direction to the forearm through the forearm connection module 23, thereby realizing rope-driven differential drive. The forearm connection module transmits the flexion, extension, and rotation output by the engagement module to the forearm.

[0059] like Figure 13As shown, the support bracket module 21 includes a support structure and support links, specifically including an inner fixed bracket 211, an inner moving bracket 212, an inner support link 213, an outer fixed bracket 214, an outer moving bracket 215, and an outer support link 216. The inner fixed bracket 211, inner moving bracket 212, outer fixed bracket 214, and outer moving bracket 215 have similar structures, as do the inner support link 213 and outer support link 216. Each support bracket has a shell and a through-hole structure. The interior of the shell is used to install the engagement module 22 and the forearm connection module 23, and the through-hole structure is used to connect the inner support link 213 and the outer support link 216.

[0060] The outer fixed bracket 214 and the inner fixed bracket 211 are fixedly connected to the arm module 1 by bolts and nuts. The outer moving bracket 215 is connected to the outer fixed bracket 214 by the outer support link 216. The inner moving bracket 212 is connected to the inner fixed bracket 211 by the inner support link 213.

[0061] like Figure 9 and Figure 10 As shown, the meshing module 22 includes a meshing fixed end module 221 and a meshing moving end module 222.

[0062] The meshing motion end module 222 is located away from the arm module 1, and the meshing fixed end module 221 is connected to the meshing motion end module 222 through the support bracket module 21. The meshing fixed end module 221 and the meshing motion end module 222 are tangential. The meshing module 22 achieves two degrees of freedom through the basic principle of rope differential drive.

[0063] The meshing fixed end module 221 includes a fixed end meshing plate 2211, a first meshing steel wire rope 2212, and four fixed end idler pulleys 2213. The four fixed end idler pulleys 2213 are installed on the fixed end meshing plate 2211 according to the holes in the fixed end meshing plate 2211. The first meshing steel wire rope 2212 is fixedly connected to the mounting groove at the meshing point of the fixed end meshing plate 2211. The four fixed end idler pulleys 2213 are used to change the connection path of the rope.

[0064] The meshing motion end module 222 includes a motion end meshing plate 2221, a second meshing steel wire rope 2222, a motion end pulley module 2223, and a motion end idler wheel 2224. Two motion end pulley modules 2223 are mounted on the mounting holes of the motion end meshing plate 2221, and multiple motion end idler wheels 2224 are mounted on the motion end meshing plate 2221 near the inner motion support 212. Similarly, the second meshing steel wire rope 2222 is fixedly connected to the mounting groove at the meshing point of the motion end meshing plate 2221. The first drive rope 15 and the second drive rope 16 are decoupled at the fixed end idler wheel 2213 and fixedly connected to the motion end pulley module 2223 for differential rope drive.

[0065] The mounting holes on the moving end engagement plate 2221 for mounting the moving end pulley module 2223 are positioned to correspond left and right to the mounting holes on the fixed end engagement plate 2211.

[0066] According to the application design requirements, four fixed-end idler wheels 2213 are installed on the fixed-end meshing plate 2211 according to the holes in the fixed-end meshing plate 2211. The meshing wire rope 2212 is fixedly connected to the mounting groove at the meshing point of the fixed-end meshing plate 2211. The fixed-end meshing plate 2211 is provided with multiple mounting holes. The outer meshing is set as an arc, which is tangent to the moving end meshing plate 2221. The mounting holes for installing the fixed-end idler wheels 2213 need to satisfy the axial symmetry relationship of the idler wheels on the left and right sides. This axis is formed by the line connecting the midpoint of the arc and the center of the arc.

[0067] like Figure 11 As shown, the forearm connection module 23 includes a forearm pulley 231, a forearm pulley support frame 232, and a forearm connection flange 233. The forearm pulley 231 is mounted on the forearm pulley support frame 232, and the forearm connection flange 233 is fixedly connected to the forearm pulley 231. The two motion-end pulley modules 2223 are respectively fixedly connected to a first transmission rope 24 and a second transmission rope 25. The first transmission rope 24 and the second transmission rope 25 pass through the motion-end pulley modules 2223 and the motion-end idler wheel 2224, and are fixedly connected to the forearm pulley 231; the rotation of the motion-end pulley modules 2223 is achieved through the forearm connection module 23, thus rotating the forearm.

[0068] It is worth noting that the transmission rope 24, through the rotation of the motion-end pulley module 2223, represents the stretching of one side of the motion-end pulley module 2223, while the other side retracts. The tangential direction of the motion-end idler wheel 2224 spatially coincides with the tangential direction of the forearm pulley 231. The left side of one drive rope passes through the left motion-end idler wheel 2224, then clockwise around the right side of the forearm pulley 231 and is fixedly connected thereto. Similarly, the other right side of this drive rope passes through the right motion-end idler wheel 2224, then clockwise around the left side of the forearm pulley 231 and is fixedly connected thereto. The number of turns depends on the actual situation. Similarly, the transmission rope 25 is connected to the forearm pulley 231 along the same path as the transmission rope 24. The combined rotation of the two motion-end pulley modules 2223 pulls the transmission ropes 24 and 25, thereby driving the forearm connection module 23 to achieve the rotation of the forearm. The two motion end pulley modules can always rotate in a consistent manner. Therefore, the two motion end modules drive the forearm pulley to rotate together. The advantage is that the rotation of the forearm is ultimately achieved by two motors working together.

[0069] The transmission rope passes through the motion end pulley module 2223 and is deflected by the motion end idler wheel 2224, and is fixedly connected to the forearm pulley. Since the two motion end pulley modules 2223 always maintain the same rotation angle, the rotation of the forearm can be achieved by rotating the two motion end pulley modules 2223.

[0070] The motion-end pulley module 2223 comprises a differential pulley 22231, a steering pulley 22232, a pulley shaft 22233, and some standard components such as bearings and screws. The differential pulley and the steering pulley are respectively fixedly connected to both ends of the pulley shaft. When the motion-end pulley module is installed on the aforementioned motion meshing plate, the differential pulley and the steering pulley are respectively close to the side of the outer support and the side of the inner support.

[0071] Each of the pulleys in the motion-end pulley module, the motor pulley, and the forearm pulley is equipped with at least two rope interfaces. The two drive ropes connect the motor pulley and the motion-end pulley module, and the two transmission ropes connect the motion-end pulley module and the forearm module.

[0072] The driven pulley is fixedly connected to both ends by drive ropes. The two drive ropes are respectively arranged at both ends of the pulley. When the two drive ropes are pulled in the same direction and for the same distance, the pulley will move in the direction of the rope movement; when the two drive ropes are pulled in opposite directions and for the same distance, the pulley will rotate at a certain angle.

[0073] In addition to achieving two degrees of freedom of outputting flexion and extension and rotation, the rope differential drive can be modified to output two degrees of freedom of outputting flexion and extension and lateral swing by changing the orientation of some components according to actual requirements.

[0074] This patent mainly proposes two points: 1. It proposes the basic principle of rope differential drive; 2. Based on the basic principle of 1, it expands and invents a flexible joint mechanism driven by rope differential drive.

[0075] like Figure 12 As shown, extending the basic principle of the rope differential drive, in this basic principle, driving ropes 15 and 16 are simultaneously pulled downwards by the same displacement, corresponding to the pulley shaft driving the pulley to move downwards, and this displacement shortens... Figure 12 The distance between the front left pulley and the rear left pulley, shown in the figure, is tangential through the meshing plate, thereby driving the forearm to flex and extend. The figure illustrates the rope layout on the left side. Let the radius of the front pulley (differential pulley 22231) be r1, and the radius of the rear pulley be r2; the arm swing angle be θ, and the length of the portion enclosed by the two pulleys and the rope be:

[0076] S1=(0.5Π+0.5θ)r1;

[0077] S2=(0.5Π-0.5θ)r2;

[0078] If we keep S1+S2 unchanged, then we have S1+S2=0.5Π(r1+r2)+ 0.5θ*(r1-r2);

[0079] To keep S1+S2 unchanged, we can set r1=r2.

[0080] Therefore, in an extended application of this principle, during flexion and extension movements, the front pulley does not rotate in the world coordinate system. In practical mechanism applications, the front pulley is the differential pulley 22231 within the motion-end pulley module 2223.

[0081] according to Figure 9 As shown, the complete wiring diagram for an extended application of this principle is illustrated. In the basic principle, any two drive ropes 15 and 16 simultaneously pull in opposite directions with the same displacement, causing the corresponding pulleys to rotate. Since the wiring positions of the left and right pulleys are opposite, the rotation angles of the two front pulleys are the same and opposite in the same world coordinate system.

[0082] Therefore, during rope differential drive, the two pulleys at the front end always have the same rotation angle relative to the inner support and the outer support.

[0083] In the description of this invention, it should be understood that the terms "longitudinal", "lateral", "up", "down", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this invention, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention.

[0084] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A rope differential driven flexible joint mechanism, comprising a pulley differential module (2) and an arm module (1) connected to each other, and a connector connecting the pulley differential module (2) and the arm module (1), wherein the pulley differential module (2) is a two-degree-of-freedom mechanism, and the arm module (1) is a base link, characterized in that: The pulley differential module (2) includes a support bracket module (21), an engagement module (22), and a forearm connection module (23). The support bracket module (21) provides installation space for the engagement module (22) and the forearm connection module (23) and improves the rigidity of the entire pulley differential module (2). The engagement module (22) realizes rope differential drive and outputs two degrees of freedom: flexion and extension and rotation. The forearm connection module (23) transmits the flexion, extension, and rotation output by the engagement module (22) to the forearm. The arm module (1) includes a first flexible actuator (11), a second flexible actuator (12), an articulated arm support (13), and a drive pretensioning device (14). The first flexible actuator (11) and the second flexible actuator (12) provide power for the stretching of the first drive rope (15) and the second drive rope (16). The drive pretensioning device (14) pretensions the first drive rope (15) and the second drive rope (16) at the initial moment. The articulated arm support (13) constitutes the shell of the arm module (1) and provides installation support for the first flexible actuator (11), the second flexible actuator (12), and the drive pretensioning device (14). In the pulley differential module (2), the support bracket module (21) is the outer shell, the engagement module (22) is installed in the support bracket module (21), and the forearm connection module (23) is installed in the part of the support bracket module (21) near the end. The meshing module (22) includes a meshing fixed end module (221) and a meshing moving end module (222). The meshing fixed end module (221) is close to the arm module (1), and the meshing moving end module (222) is far from the arm module (1). The meshing fixed end module (221) is connected to the meshing moving end module (222) through the support bracket module (21). The meshing fixed end module (221) and the meshing moving end module (222) are tangential. The meshing module (22) realizes two degrees of freedom through the basic principle of rope differential drive. The meshing fixed end module (221) includes a fixed end meshing plate (2211), a first meshing wire rope (2212), and four fixed end idler pulleys (2213). The four fixed end idler pulleys (2213) are installed on the fixed end meshing plate (2211) according to the holes in the fixed end meshing plate (2211). The first meshing wire rope (2212) is fixedly connected to the mounting groove at the meshing point of the fixed end meshing plate (2211). The four fixed end idler pulleys (2213) are used to change the connection path of the rope. The meshing motion end module (222) includes a motion end meshing plate (2221), a second meshing steel wire rope (2222), a motion end pulley module (2223), and a motion end idler wheel (2224). Two motion end pulley modules (2223) are installed on the mounting holes of the motion end meshing plate (2221), and multiple motion end idler wheels (2224) are installed on the motion end meshing plate (2221) on the side near the inner motion bracket (212). Similarly, the second meshing steel wire rope (2222) is fixedly connected to the mounting groove at the meshing point of the motion end meshing plate (2221). The first drive rope (15) and the second drive rope (16) are decoupled and fixedly connected to the differential drive of the rope on the moving end pulley module (2223) through the idler wheel (2213) at the fixed end; The forearm connection module (23) includes a forearm pulley (231), a forearm pulley support frame (232), and a forearm connection flange (233). The forearm pulley (231) is mounted on the forearm pulley support frame (232), and the forearm connection flange (233) is fixedly connected to the forearm pulley (231). The first transmission rope (24) and the second transmission rope (25) are turned by the motion end pulley module (2223) and the motion end idler wheel (2224), and are fixedly connected to the forearm pulley (231). The rotation of the motion end pulley module (2223) is achieved by the forearm connection module (23) to realize the rotation of the forearm.

2. The flexible joint mechanism with cable differential drive according to claim 1, characterized in that: In the arm module (1), the articulated arm bracket (13) is fixedly connected to the support bracket module (21) through a connector. The articulated arm bracket (13) and the support bracket module (21) can be combined into one unit. The rotation of the first flexible actuator (11) and the second flexible actuator (12) drives the first drive rope (15) and the second drive rope (16) to be stretched. The drive pre-tightening device (14) achieves the pre-tightening of the first drive rope (15) and the second drive rope (16) by adjusting the position of the first flexible actuator (11) and the second flexible actuator (12).

3. The flexible joint mechanism with cable differential drive according to claim 2, characterized in that: The support bracket module (21) includes a support structure and a support link, specifically including an inner fixed bracket (211), an inner moving bracket (212), an inner support link (213), an outer fixed bracket (214), an outer moving bracket (215), and an outer support link (216). The inner fixed bracket (211), the inner moving bracket (212), the outer fixed bracket (214) and the outer moving bracket (215) have similar structures. The inner support link (213) and the outer support link (216) have similar structures. Each support bracket is provided with a shell and a through hole structure. The inside of the shell is used to install the meshing module (22) and the forearm connecting module (23). The through hole structure is used to connect the inner support link (213) and the outer support link (216).

4. The flexible joint mechanism with cable differential drive according to claim 2, characterized in that: The first flexible actuator (11) and the second flexible actuator (12) are a SEA that can measure torque by detecting the deformation of the internal spring. The first flexible actuator (11) and the second flexible actuator (12) are respectively connected to one end of the first drive rope (15) and the second drive rope (16). The articulated arm bracket (13) serves as the housing of the arm module (1) and is used to install the first flexible actuator (11), the second flexible actuator (12) and the drive pretensioning device (14). The drive pretensioning device (14) is used to initially pretension the first drive rope (15) and the second drive rope (16).

5. The flexible joint mechanism with cable differential drive according to claim 4, characterized in that: Both the first flexible actuator (11) and the second flexible actuator (12) include a servo motor (111), a motor bracket (112), a gear shaft (113), a torsion spring (114), a motor pulley (115), an encoder (116), a first helical gear (117), and a second helical gear (118). The output force is transmitted from the servo motor (111) to the gear pair of the first helical gear (117) and the second helical gear (118), and then the torsion spring (114) drives the motor pulley (115) to rotate, thereby realizing the extension and retraction of the first drive rope (15) and the second drive rope (16). The encoder (116) is used to measure the amount of rotation of the motor pulley (115) relative to the motor bracket (112) caused by the presence of the torsion spring (114). Based on the amount of rotation and the stiffness of the torsion spring (114), the torque output by the first flexible actuator (11) and the second flexible actuator (12) can be calculated, providing a hardware basis for force control at the control level.

6. The flexible joint mechanism with cable differential drive according to claim 4, characterized in that: The articulated arm bracket (13) serves as the main support part of the arm module (1). It is equipped with a mating plate and multiple mating holes to provide installation space for the first flexible actuator (11), the second flexible actuator (12), the first drive rope (15), and the second drive rope (16) pre-tensioning device.

7. The flexible joint mechanism with cable differential drive according to claim 4, characterized in that: The drive pretensioning device (14) includes a first slider guide rail module (141), a second pulley guide rail module and a double lead screw module (142). The first slider guide rail module (141) and the second pulley guide rail module cooperate with the first flexible actuator (11) and the second flexible actuator (12). The housings of the first flexible actuator (11) and the second flexible actuator (12) cooperate with the nuts on the double lead screw module (142) to finally realize the adjustability of the front and rear positions of the first flexible actuator (11) and the second flexible actuator (12). By adjusting the positions of the first flexible actuator (11) and the second flexible actuator (12), the first drive rope (15) and the second drive rope (16) are pretensioned.

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