Robot joint module with flexible element and double encoders for torque measurement

Abstract

The invention discloses a robot joint module with a flexible element and double encoders for torque measurement, and belongs to the technical field of robots. The joint module mainly comprises a motor, a harmonic reducer, a flexible link and two encoders mounted at the two ends of the flexible link respectively. Wherein the motor and the speed reducer are used for providing power for driving the joint module to rotate; a three-layer structure flexible link is arranged at the output end of the joint module, a rubber ring with a plurality of petal bodies designed in the circumferential direction is adopted in the middle layer, and the petal bodies are arranged between the adjacent joints in the joints designed on the upper layer and the lower layer respectively, so that the flexible link can generate tiny elastic deformation when the joint is stressed, external impact can be absorbed, and the joint can be protected from being damaged. Meanwhile, the encoders at the two ends of the flexible link are used for detecting the relative rotation angle change of the flexible link, so that the torque of the output end of the joint is obtained, and the torque observation function is achieved. Compared with a common planetary reducer, the planetary reducer has higher transmission precision, smaller return difference and more compact size.

Description

Technical Field

[0002] The present invention relates to the field of robotics, and in particular to a joint module used in a robot, specifically a robot joint module with a flexible element and a dual encoder torque measurement, which is suitable for a robot joint actuator with high-precision control and impact resistance requirements. Background Art

[0004] The rapid development of robotics, particularly in high-dynamic performance platforms like humanoid robots and quadruped robots, places ever-higher demands on joint modules for integration, precision, and impact resistance. Existing robotic joint modules typically utilize a motor drive combined with a reducer (such as a planetary reducer or harmonic reducer) to output motion. However, these motors and reducers are susceptible to damage from external shocks or collisions, compromising system reliability.

[0005] Currently, most robot joints on the market use rigid connection structures, which make it difficult for the joints to effectively buffer external impacts during operation. This makes the motor and reducer components susceptible to damage, reducing the reliability and service life of the robot system. In addition, many robot systems require the perception of joint output torque. Existing torque measurement solutions typically rely on additional force sensors, but traditional torque sensors are large, expensive, and difficult to integrate, making them difficult to use in miniaturized, high-density joint modules. Some existing torque estimation methods rely on current sensing, but this is affected by various interference factors and has limited estimation accuracy.

[0006] Therefore, there is an urgent need for a motor joint module with a compact structure, measurable output torque, and certain impact resistance to solve the above problems. Summary of the Invention

[0008] To address technical issues such as the vulnerability of existing robot joints to damage to motors and reducers when subjected to external force impacts, difficulty in measuring output torque, and insufficient measurement accuracy, the present invention proposes a robot joint module with a flexible element and dual encoder torque measurement. This module utilizes an innovatively designed flexible link as an elastic element connecting the output of the harmonic reducer with the output of the joint, achieving the introduction of a limited flexible structure without compromising stiffness requirements. This flexible link is capable of producing minute elastic deformations when subjected to external force impacts, thereby effectively buffering the impact and protecting the motor and reducer from damage. Encoders are installed at both ends of the flexible link to detect the angular difference in real time. This angular difference is combined with the torsional stiffness of the flexible link for calculation, enabling highly accurate indirect measurement of torque information at the output end.

[0009] The present invention has a robot joint module with flexible elements and dual encoder torque measurement, including a motor installed in the joint module shell, a harmonic reducer, a flexible link, a joint module output end cover, an end encoder, and an intermediate encoder, which constitute a joint module as a whole.

[0010] The output end of the motor is connected to the input end of the harmonic reducer through a coupling; the motor and the harmonic reducer are coaxially sleeved on the hollow support shaft, and the two ends of the hollow support shaft are respectively fixedly connected to the motor and the harmonic reducer.

[0011] The flexible link comprises an upper flexible link support, a rubber ring, and a lower flexible link support. The bottom surface of the upper flexible link support and the top surface of the lower flexible ring support are circumferentially spaced with m joints. The outer wall of the rubber ring is circumferentially spaced with m petals at equal angles; m is an even number greater than or equal to 2.

[0012] The rubber ring structure described above is positioned between the upper and lower flexible link supports. The petals of the rubber ring are grouped in pairs, with each group containing two adjacent petals. The upper flexible ring support is then moved downward from the top of the rubber ring to insert each connector between the two petals in each group, with the left and right sides of the connectors abutting the opposing sides of the adjacent petals. The lower flexible ring support is then moved upward from the bottom of the rubber ring to insert each connector between adjacent petals in adjacent groups, with the left and right sides of the connectors abutting the opposing sides of the adjacent petals in the adjacent groups.

[0013] The flexible link is coaxially mounted with an upper and lower annular bearing seats at the top and bottom, respectively, within the dual-bearing housing. The upper annular bearing seat is fixedly connected to the upper flexible link bracket, while the lower annular bearing seat is fixedly connected to the lower flexible link bracket. The upper and lower annular bearing seats are connected to the dual-bearing housing via bearings, forming a revolute pair. The dual-bearing housing is fixedly connected to the joint module housing. The end of the upper flexible link bracket serves as the output port for connecting to a load. The flexible link provides a torsional elastic connection between the joint module and the load.

[0014] The intermediate encoder is installed between the flexible link and the harmonic reducer. Its stator is fixed to the bottom surface of an annular stator frame, which is connected and fixed to the bottom end of the dual-bearing housing. Its rotor is fixed to the bottom surface of an annular rotor frame, which is connected and fixed to the lower flexible annular support. The intermediate encoder detects the angle information at the output end of the harmonic reducer.

[0015] The end encoder is mounted at the output end of the flexible link. Its rotor is fixedly connected via internal threads to a central protrusion on the inner side of the joint module output cover, located at the output end of the flexible link. Its stator is fixedly mounted at the top of the hollow support shaft. The joint module output cover is fixedly connected to the upper flexible link bracket. The end encoder detects the actual output angle of the joint module.

[0016] The signals of the end encoders and the intermediate encoder are transmitted to the main control unit via a high-speed communication interface, and angle and torque calculations are performed in real time.

[0017] The advantages of the present invention are:

[0018] 1. The present invention has a robot joint module with flexible elements and dual encoders for torque measurement.

[0019] The flexible link realizes efficient impact buffering capability and effectively protects the motor and reducer.

[0020] 2. The present invention has a robot joint module with a flexible element and dual encoder torque measurement. Dual encoders are installed on both sides of the flexible link to measure the angle difference of the flexible link, thereby indirectly achieving high-precision output torque measurement.

[0021] 3. The present invention has a robot joint module with flexible elements and dual encoders to measure torque, which reduces the torque

[0022] demand and improved energy efficiency and dynamic responsiveness.

[0023] 4. The flexible link involved in the present invention not only has basic impact absorption and torque sensing functions, but also forms an "energy storage and return" function similar to biological tendons in dynamic alternating motion scenarios, providing important support for the high-frequency and flexible control of the robot system.

[0024] 5. The present invention has a robot joint module with flexible elements and dual encoders for torque measurement, which can reduce the harmonic

[0025] The speed reducer improves transmission accuracy and control response speed.

[0026] 6. The present invention has a robot joint module with flexible elements and dual encoders to measure torque, which realizes the measurement

[0027] The organic integration of force structure and power transmission structure significantly improves the structural compactness and measurement reliability of the joint module.

[0028] 7. The robot joint module of the present invention has a flexible element and a dual encoder torque measurement, has a high degree of integration, and adopts a modular design, which is conducive to the assembly of a multi-degree-of-freedom system. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is a schematic diagram of the overall structure of the robot joint module;

[0031] Figure 2 This is a schematic diagram of the flexible link and encoder installation structure of the joint module;

[0032] Figure 3 Schematic diagram of the structural composition of the flexible link;

[0033] Figure 4 Schematic diagram of elastic deformation of the flexible link at the moment of impact;

[0034] Figure 5 This is a schematic diagram of the joint module applied to a quadruped robot;

[0035] Figure 6 This is a schematic diagram of the joint module applied to a biped robot.

[0036] In the picture:

[0037] 1-Motor 2-Harmonic reducer 3-Flexible link 4-Joint module output cover 5-end encoder 6-Intermediate encoder 7-Joint module outer shell 8- Main control unit 9-End cap 10-Hollow support shaft 11-Reducer positioning platform 12-ring rotor frame 13- Ring stator frame 302-Rubber Ring 303-lower flexible link bracket 304-ring structure end face 305-connector 306-Inner Ring 307-valve 308-upper annular bearing seat 309-lower annular bearing seat 310-Dual bearing housing DETAILED DESCRIPTION

[0039] The specific implementation of the robot joint module of the present invention is described in detail below with reference to the accompanying drawings.

[0040] The present invention has a robot joint module with flexible elements and dual encoders for torque measurement, which is mainly composed of a motor 1, a harmonic reducer 2, a flexible link 3, a joint module output end cover 4, an end encoder 5, and an intermediate encoder 6. The whole is coaxially installed in a cylindrical joint module outer shell 7, as shown in FIG. Figure 1 shown.

[0041] The motor 1 is a brushless DC motor with the characteristics of high power density, high speed and long life. Its output end is connected to the input end of the harmonic reducer 2 through a coupling. The harmonic reducer 2 converts the high-speed, low-torque output of the motor 1 into a low-speed, high-torque output. The motor 1 and the harmonic reducer 2 are coaxially sleeved on the hollow support shaft 10 from bottom to top. The end of the hollow support shaft 10 has a connecting end that is fixed to the bottom surface of the motor 1 by screws. At the same time, a reducer positioning platform 11 is fixed to the top of the hollow support shaft 10 by screws evenly distributed around the circumference. The reducer positioning platform 11 is designed with openings on the circumference, which are plugged into the columnar protrusions designed on the end of the harmonic reducer 2. The circumferential positioning between the harmonic reducer 2 and the hollow support shaft 10 is achieved through the reducer positioning platform 11. The above-mentioned motor 1 is connected and fixed to the joint module outer shell 7 on the circumference by screws. The bottom surface of motor 1 also features an annular sidewall, forming a control chamber within which resides a main control unit 8. This unit is secured to the end of a hollow support shaft 10 via bolts evenly spaced around the perimeter. The control chamber is further sealed by an end cap 9 fixed to the end of the annular sidewall. Motor 1 also incorporates a motor-end encoder to measure motor angle and speed.

[0042] The above design allows the joint module of the present invention to have a hollow structure. The harmonic reducer 2 and the annular main control unit 8 are fixed by the hollow support shaft 10, so that the entire joint module forms an axial hollow channel with a maximum hollow diameter of not less than 15mm, thereby enabling the joint module to have completely internal wiring. At the same time, the harmonic reducer 2 used above has higher transmission accuracy and transmission efficiency than the planetary reducers commonly used on the market, further improving the control accuracy and response speed of the joint module.

[0043] The flexible link 3 includes an upper flexible link bracket 301, a rubber ring 302 and a lower flexible link bracket 303. Figure 2 、 Figure 3 shown.

[0044] The upper flexible segment bracket 301 and the lower flexible ring bracket 303 have the same structural dimensions and feature a circular end face 304. Six joints 305 are circumferentially spaced evenly around the lower surface of the end face. The inner and outer sides of the joints 305 are curved, coplanar with the inner and outer sides of the circular end face 304. The left and right sides of the joints 305 are concave arcs, and the bottom surface of the joints is flat and parallel to the circular end face 304.

[0045] The rubber ring 302 is an integral annular multi-lobe structure composed of 12 lobes 307 which are equiangularly spaced on the outer wall of the inner ring 306. The inner wall of each lobe 307 is connected with the outer wall of the inner ring 306, and the upper and lower walls are parallel to the cross section of the inner ring 306; meanwhile, the left and right walls are convex arc surfaces with the same curvature as the inner concave arc surfaces on the left and right sides of the joint 305 on the upper and lower flexible link supports 301 and 303.

[0046] The rubber ring 302 with the above structure is located between the upper and lower flexible link supports 301 and 303, and the three are coaxially arranged. The lobes 307 on the circumference of the rubber ring 302 are grouped two by two, and each group has two adjacent lobes 307. The upper flexible ring support 301 is inserted into the two lobes 307 in each group from top to bottom, and at this time, the inner concave arc surfaces on the two sides of the joint 305 are tightly fitted with the opposite convex arc surfaces of the adjacent lobes 307, while the lower flexible ring support 303 is inserted into the adjacent lobes 307 in the adjacent group from bottom to top, and at this time, the inner concave arc surfaces on the two sides of the joint 305 are tightly fitted with the opposite convex arc surfaces of the adjacent lobes 307 in the adjacent group.

[0047] The top and bottom of the flexible link 3 are sleeved with the upper and lower annular bearing seats 308 and 309, and are coaxially arranged in the double-bearing housing 310. Among them, the upper annular bearing seat 308 is connected and fixed with the upper flexible link support 301 through three circumferentially distributed screws. The lower annular bearing seat 309 is connected and fixed with the lower flexible link support 302 through three circumferentially distributed screws. At the same time, the bearings sleeved on the upper and lower annular bearing seats 309 are connected between the double-bearing housing 310 to form a rotating pair. Further, the top surface of the double-bearing housing 310 is connected and fixed with the circumferential shoulder of the top surface of the joint module shell 7 through circumferentially distributed screws.

[0048] Thus, the flexible link 3 can realize the torsional elastic connection between the joint module of the application and the load. In the flexible link 3, one end of the upper flexible link support 301 is an output end for connecting the load (joint module connecting device, such as a mechanical arm or a robot leg link). Since the middle layer of the flexible link 3 is the rubber ring 302, the flexible link 3 will deform when subjected to torque; therefore, when the joint module of the application is subjected to impact or load, half of the lobes 307 on the circumference of the rubber ring 302 will be in a compressed state, and the remaining lobes 307 will be in a neutral state, forming a symmetrical strain response distribution, and producing a torsional elastic deformation, as shown in Figure 4 .

[0049] During the actual working process of the joint module of the present invention, the working condition is usually reciprocating rotation. Therefore, when the joint module performs the reciprocating rotation task, the rubber ring 302 of the flexible link 3 will undergo directional elastic deformation during each joint rotation, thereby storing elastic potential energy. Specifically, when the joint rotates from the initial position A in the clockwise / counterclockwise direction to the position B, the rubber ring 302 in the middle of the flexible link is locally compressed, forming a certain torsional deformation. Part of the energy in this process is stored by the flexible link 3; when the joint then returns from position B to position A in the counterclockwise / clockwise direction, the rubber ring 302 will release the previously stored energy due to its own elastic recovery performance, thereby generating additional assist torque at the initial stage of reverse movement. This energy storage characteristic similar to that of biological tendons enables the joint module to meet actual working requirements with a smaller output torque, while also improving energy efficiency and dynamic response capabilities, and can absorb impact energy without destroying the mechanical connection, reduce stress concentration, and effectively extend the service life of the harmonic reducer and motor. This "self-assisted" feature has the following technical advantages:

[0050] ① Reduce the peak load of the motor: The reaction torque provided by the rubber rebound can offset part of the motor output torque in the initial stage of reverse rotation, reduce the motor load and extend the motor life;

[0051] ② Improve the dynamic response performance of joints: Since the elastic release of the flexible link is a fast response, combined with the closed-loop control strategy, it can improve the response speed and trajectory accuracy of the joint module in actions such as frequent starts and stops and rapid rotation;

[0052] ③ Enhanced control system stability: The dynamic power-assistance effect can form a natural buffer mechanism at the control level, reducing torque jumps under high-speed switching conditions and improving system control robustness;

[0053] ④ Energy saving and consumption reduction: In frequent alternating motion, the actual output energy of the motor can be reduced, partial elastic energy feedback can be achieved, and the overall energy efficiency of the module can be improved;

[0054] The number of actuators 307 circumferentially disposed on the rubber ring 302 can be determined by analyzing the external load capacity of the rubber ring 302. In this embodiment, 12 actuators are used, resulting in a maximum joint module output of 81 NM. Simulation tests have estimated the service life of the flexible link 3 to be approximately 100,000 reciprocating joint rotations.

[0055] At the same time, the size of the flexible link 3 is designed according to the rated load and torsional stiffness requirements of the robot joint. The material and structure of the flexible link can be adjusted according to the application requirements of different robots. For example, elastic alloy materials with different stiffness are used as the middle layer to adapt to a wider range of load changes and impact absorption requirements.

[0056] like Figure 1As shown, the end encoder 5 and the intermediate encoder 6 are both magnetic encoders, with high resolution and environmental interference resistance, suitable for use in complex conditions such as industrial robots.

[0057] The intermediate encoder 6 is installed between the flexible link 3 and the harmonic reducer 2, and is used to detect the angle information of the output end of the harmonic reducer 2. The stator of the intermediate encoder 6 is fixed to the bottom surface of a ring-shaped stator holder 13 through circumferentially distributed screws, and the ring-shaped stator holder 13 is connected and fixed to the bottom end of the double-bearing housing 310 through circumferentially distributed screws. The rotor of the intermediate encoder 6 is fixedly installed on the bottom surface of a ring-shaped rotor holder 12 through circumferentially distributed screws, and the ring-shaped rotor holder 12 is connected and fixed to the lower flexible ring-shaped support 303 through circumferentially distributed screws passing through the through holes in the lower ring-shaped bearing seat 309.

[0058] The end encoder 5 is installed at the output end of the flexible link 3, and is used to detect the actual output angle of the joint module. The rotor of the end encoder 5 is connected and fixed through thread cooperation between the inner threads and the outer thread protrusions on the inside of a joint module output end cover 4 provided at the output end of the flexible link 3. The stator of the end encoder 5 is fixedly installed on the encoder mounting table fixedly installed on the reducer positioning table 11 at the top end of the hollow support shaft 10. The joint module output end cover 4 is connected and fixed between the upper flexible link support 301 through circumferentially distributed screws, and the top of the flexible link 1 is sealed through the joint module output end cover 4.

[0059] The signals of the above-mentioned end encoder 5 and intermediate encoder 6 are transmitted to the main control unit 8 through a high-speed communication interface for real-time angle and torque calculation. When the intermediate encoder 6 is installed, the designed ring-shaped stator holder 13 and ring-shaped rotor holder 12 are used to realize the positioning of the bearings, specifically: the upper and lower ends of the inner ring of the upper ring-shaped bearing are limited by the circumferential shoulder of the outer wall of the joint module output end cover 4 and the circumferential shoulder of the inner wall of the double-bearing housing 310, respectively. The upper and lower ends of the outer ring of the upper ring-shaped bearing are limited by the circumferential shoulder of the top surface of the joint module housing 7 and the circumferential shoulder of the inner wall of the double-bearing housing 310, respectively. The upper and lower ends of the inner ring of the lower ring-shaped bearing are limited by the circumferential shoulder of the outer wall of the lower ring-shaped bearing seat 309 and the ring-shaped rotor holder 12, respectively. The upper and lower ends of the outer ring of the lower ring-shaped bearing are limited by the circumferential shoulder of the top surface of the joint module housing 7 and the ring-shaped stator holder 13, respectively.

[0060] When the robot performs a task and encounters a sudden impact or high dynamic load at the joint output, the rubber ring 302 in the flexible link 3 will produce a certain angular offset, resulting in an angular position difference Δθ between the two flexible link brackets. During this process, the end encoder 5 and the intermediate encoder 6 respectively collect the angle signals at both ends of the flexible link 3. The main control unit then calculates the difference between the two angle signals and the equivalent torsional stiffness coefficient of the flexible link 3 to accurately calculate the torque acting on the joint module output, achieving high-precision torque sensing. This torque measurement process does not require an external force sensor, does not increase the system weight and complexity, and avoids the risk of failure due to mechanical contact. This method offers the advantages of low cost, high integration, and high dynamic response, making it suitable for torque closed-loop control and impedance control in robot control.

[0061] The modular design of the joint module of the present invention is not only convenient for integration into various robot platforms, especially humanoid robots and quadruped robots that require high-precision motion and high robustness, but also has good scalability and adaptability; a three-degree-of-freedom joint module can be assembled by matching three joint modules with a joint connector, such as connecting the joint module output end cover 4 at the front end of the joint module B to the end of the joint module A, and further connecting the joint module output end cover 4 at the front end of the joint module C through the joint connector 1 at the end of the joint module B, such as Figure 5 As shown; further, through the four assembled three-degree-of-freedom joint modules, combined with the limbs, body and other structures, a quadruped robot can be constructed, as shown Figure 5 As shown. Installing 10 of these joint modules on the two legs of a biped robot will give a single-leg 5-DOF biped robot lower limb structure. The joint modules are symmetrically distributed on the two legs. In the single leg, there are 3 joint modules located at the hip joint, namely the hip pitch joint module, the hip lateral swing joint module, and the hip rotation joint module, which are responsible for the lifting and lowering of the thigh, the lateral separation and retraction of the thigh, and the rotation of the thigh, respectively. There is also a knee joint module responsible for the lifting and lowering of the calf, and an ankle joint module responsible for the lifting and lowering of the toes. Figure 6 shown.

Claims

1. A robot joint module with a flexible element and dual encoder torque measurement, characterized by: The joint module comprises a motor, a harmonic reducer, a flexible link, a joint module output end cover, an end encoder, and an intermediate encoder installed in the outer shell of the joint module, which together constitute a joint module. The output end of the motor is connected to the input end of the harmonic reducer through a coupling; the motor and the harmonic reducer are coaxially sleeved on the hollow support shaft, and the two ends of the hollow support shaft are respectively fixedly connected to the motor and the harmonic reducer; The flexible link comprises an upper flexible link bracket, a rubber ring, and a lower flexible link bracket; wherein the bottom surface of the upper flexible link bracket and the top surface of the lower flexible ring bracket are circumferentially and evenly spaced with m joints; the outer wall of the rubber ring is circumferentially and evenly spaced with 2m petals; m is an even number greater than or equal to 2; The rubber ring of the above structure is positioned between the upper flexible segment support and the lower flexible segment support; the petals on the circumferential direction of the rubber ring are grouped in pairs, with the two petals in each group adjacent to each other; the upper flexible ring support is moved downward from the top of the rubber ring to insert each connector between the two petals in each group, with the left and right sides of the connector respectively fitting against the opposite sides of the adjacent petals; the lower flexible ring support is moved upward from the bottom of the rubber ring to insert each connector between adjacent petals in adjacent groups, with the left and right sides of the connector respectively fitting against the opposite sides of the adjacent petals in adjacent groups; The upper and lower annular bearing seats are sleeved on the top and bottom of the flexible link and are coaxially placed in the dual-bearing housing; the upper annular bearing seat is fixedly connected to the upper flexible link bracket; the lower annular bearing seat is fixedly connected to the lower flexible link bracket; the upper and lower annular bearing seats are connected to the dual-bearing housing through bearings to form a revolving pair; the dual-bearing housing is fixedly connected to the joint module housing; the end where the upper flexible link bracket is located is the output end, used to connect the load, and the flexible link realizes the torsional elastic connection between the joint module and the load; The intermediate encoder is installed between the flexible link and the harmonic reducer. The stator of the intermediate encoder is fixed to the bottom surface of an annular stator frame, which is fixedly connected to the bottom end of the aforementioned double-bearing housing. The rotor of the intermediate encoder is fixedly installed to the bottom surface of an annular rotor frame, which is fixedly connected to the lower flexible annular bracket. The intermediate encoder detects the angle information of the output end of the harmonic reducer. The end encoder is installed at the output end of the flexible link; the rotor of the end encoder is fixedly connected to a protrusion at the center position of the inner side of the output end cover of the joint module provided at the output end of the flexible link through an internal thread; the stator of the end encoder is fixedly installed at the top of the hollow support shaft; the output end cover of the joint module is connected and fixed to the upper flexible link bracket; the end encoder detects the actual output angle of the joint module; The signals of the end encoders and the intermediate encoder are transmitted to the main control unit via a high-speed communication interface, and angle and torque calculations are performed in real time.

2. A robot joint module with a flexible element and dual encoder torque measurement according to claim 1, characterized in that: The main control unit is fixedly installed at the end of the hollow support shaft, and the main control unit is also located in a control cavity designed on the bottom surface of the motor; the control cavity is further sealed by an end cover fixedly installed at the end of the annular wall.

3. A robot joint module with a flexible element and dual encoder torque measurement according to claim 1, characterized in that: The left and right surfaces of the joints on the upper flexible link bracket and the lower flexible ring bracket are designed to be concave arc surfaces.

4. A robot joint module with a flexible element and dual encoder torque measurement according to claim 1, characterized in that: The bearings are positioned by the annular stator frame and the annular rotor frame; the upper and lower ends of the inner ring of the upper annular bearing are respectively limited by the output end cover of the joint module and the circumferential shoulders of the outer wall of the upper annular bearing seat, and the upper and lower ends of the outer ring of the upper annular bearing are respectively limited by the circumferential shoulders of the top surface of the joint module outer shell and the circumferential shoulders of the inner wall of the double bearing outer shell; the upper and lower ends of the inner ring of the lower annular bearing are respectively limited by the circumferential shoulders of the outer wall of the lower annular bearing seat and the annular rotor frame, and the upper and lower ends of the outer ring of the lower annular bearing are respectively limited by the circumferential shoulders of the top surface of the joint module outer shell and the annular stator frame.

5. A robot joint module with a flexible element and dual encoder torque measurement according to claim 1, characterized in that: When the flexible link is subjected to torque, it deforms, causing the circumferential part of the rubber ring to be in a compressed state and the remaining petals to be in a neutral state, forming a symmetrical strain response distribution and generating torsional elastic deformation. At the same time, the upper and lower flexible link brackets form an angular position difference Δθ; during the process, the end encoder and the middle encoder respectively collect the angle signals at both ends of the flexible link, and then the main control unit can calculate the difference between the two angle signals and the equivalent torsional stiffness coefficient of the flexible link, and calculate the torque applied to the output end of the joint module.

6. A robot joint module with a flexible element and dual encoder torque measurement according to claim 1, characterized in that: A three-degree-of-freedom joint module is assembled by combining three joint modules with a joint connector. Specifically, the joint module output end cover at the front end of joint module B is connected to the end of joint module A, and the joint module output end cover at the front end of joint module C is further connected at the end of joint module B through the joint connector.

7. A robot joint module with a flexible element and dual encoder torque measurement according to claim 6, characterized in that: A quadruped robot is formed by combining limbs, legs and body through four assembled three-degree-of-freedom joint modules.

8. A robot joint module with a flexible element and dual encoder torque measurement according to claim 6, characterized in that: Ten joint modules are installed on the two legs of the bipedal robot to obtain a bipedal robot lower limb structure with a single-leg degree of freedom. The joint modules are symmetrically distributed on the two legs. In the single-limb leg, there are three joint modules located at the hip joint, namely the hip pitch joint module, the hip lateral swing joint module, and the hip rotation joint module, which are responsible for the lifting and lowering of the thigh, the lateral separation and contraction of the thigh, and the rotation of the thigh, respectively. One knee joint joint module is responsible for the lifting and lowering of the calf, and one ankle joint joint module is responsible for the lifting and lowering of the toes.

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