Robot leg transmission structure with flexible joint, common rigid joint and flexible link

Abstract

The invention discloses a robot leg transmission structure with a flexible joint, a common rigid joint and a flexible link. The robot leg transmission structure mainly comprises a motor module, a connecting rod transmission module and a sole module. The motor module is composed of two motor joint modules with the flexible torque measuring function, a rigid joint module and a motor connecting piece, and multi-axis cooperative driving is achieved. The connecting rod transmission module is of a parallel four-rod structure, a driving crank is connected with the output end of a rigid joint, a flexible crank structure formed by compounding aluminum alloy and a rubber layer is adopted, and good buffering capacity and dynamic response performance are achieved. The sole module is of a multi-cavity air chamber structure and comprises a conical hole used for absorbing high-frequency vibration, a main air chamber used for absorbing low-frequency impact and a supporting column structure used for preventing collapse, a force sensor is arranged on the top, and real-time force sensing of the foot end is achieved. The transmission configuration has excellent impact resistance, structural flexibility and sensing integration, and is suitable for robot platforms in various complex terrains and dynamic task environments.

Description

Technical Field

[0002] The present invention belongs to the field of robot structure design, and specifically relates to a robot leg transmission configuration that integrates a flexible drive mechanism, a connecting rod coordination structure, a foot-end buffer system and a force feedback function. It is suitable for quadruped robots and other bionic robot platforms, and is one of the key technologies for high-performance robot motion control and structural optimization. Background Art

[0004] With the growing demand for mobile robots to perform tasks in complex environments, their leg structures are facing higher requirements for high dynamic response capabilities, impact buffering capabilities, and perception accuracy. Most existing robot leg structures mainly use a solution that directly connects rigid motors to joints. Although this has certain advantages in simplifying control and improving force output, it is prone to motor overload, structural fatigue, and even failure when faced with terrain uncertainty, high-frequency micro-vibrations, or sudden external force impacts, seriously affecting system stability and service life. In addition, traditional structures often lack the ability to accurately measure external forces at the foot end, making it difficult to achieve closed-loop regulation based on force control, limiting their adaptability in complex scenarios.

[0005] While previous studies have attempted to incorporate flexible elements or cushioning structures into joint modules, most have failed to form a unified and coordinated structural system, lacking a complete technical solution that integrates flexible drive, linkage transmission, foot cushioning, and sensing systems. Therefore, a robot leg transmission configuration that combines structural flexibility, impact cushioning, and force sensing capabilities is urgently needed to improve the overall performance and reliability of the robot system in complex environments. Summary of the Invention

[0007] In order to solve the above technical problems, the present invention proposes a robot leg transmission configuration consisting of flexible joints and ordinary rigid joints plus flexible links. It is a high-performance robot leg transmission configuration that integrates drive, flexible buffering, force perception and modularization. It has a reasonable structural design and high functional integration. It is particularly suitable for mobile robot systems with high requirements on stability, impact resistance and environmental adaptability, and has broad application prospects and promotion value.

[0008] The transmission configuration of the robot leg of the present invention, which comprises a flexible joint and an ordinary rigid joint plus a flexible link, includes a motor module integrating drive and perception, a rigid-flexible coordinated connecting rod transmission module, and a sole buffer.

[0009] The drive and perception integrated motor module includes a first flexible motor joint module, a second flexible motor joint module, a rigid motor joint module and a joint connector.

[0010] The rigid motor joint module is a drive motor. The first and second flexible motor joint modules share the same structure, consisting of an outer shell, a motor mounted within the shell, a reducer, and a flexible element. The motor output is coaxially connected to the reducer and secured to the outer shell input. The flexible element is mounted at the outer shell input and connected to the reducer output, providing a torsionally elastic connection with the load.

[0011] Two encoders are installed at each end of the flexible element. The encoder at the output end of the flexible element is used to detect changes in the output angle of the flexible element; the encoder at the other end is used to detect changes in the reducer angle, thereby monitoring changes in the angle between the upper and lower layers of the flexible element. This allows the first flexible motor joint module 101 and the second flexible motor joint module 102 to output real-time torque signals.

[0012] The joint connection component is used to realize the connection between the first flexible motor module, the second flexible motor joint module and the rigid motor joint module, including a coaxial connection between the end of the rigid motor joint module shell and the output end of the outer shell of the first flexible motor joint module, and the connection of the second flexible motor joint module, and the axis of the second flexible motor joint module is perpendicular to the axis of the rigid motor joint module.

[0013] The rigid-flexible coordinated connecting rod transmission module is used to transmit joint driving force and coordinate the movement between joints. It adopts a parallel four-bar mechanism, including an active crank, a thigh shell, a thigh connecting rod, a driven crank and a calf.

[0014] The active crank's flexible end is fixedly mounted to the output of the rigid motor joint module, creating a torsionally elastic connection between the two. This provides flexibility in the joint's torsional direction during movement. The active crank's front end connects to the end of the thigh connecting rod, forming a revolute pair; the thigh connecting rod's front end connects to the front end of the driven crank, forming a revolute pair. The driven crank's end is designed with a plug that secures it to the end of the calf; the front end of the calf connects to the foot cushion.

[0015] The above-mentioned active crank, thigh connecting rod and driven crank are located in the thigh shell. The end of the thigh shell is fixedly connected to the end of the rigid motor joint module body, and the front end is connected to the end of the driven crank to form a rotating pair.

[0016] The advantages of the present invention are:

[0017] 1. The transmission configuration of the robot leg of the present invention, which combines flexible joints with ordinary rigid joints plus flexible links, has a rigid-flexible coupling drive capability by introducing flexible elements and dual encoders into the motor module. This can adapt to severe dynamic impact environments and improve the impact resistance of the joint module.

[0018] 2、The flexible joint and the ordinary rigid joint plus the flexible link robot leg transmission configuration of the application, the design of the rigid and flexible collaborative ability of the connecting rod transmission module, the use of composite flexible driving crank and driven crank, improve the force transmission smoothness and rigid and flexible coordination ability of the parallel four-bar mechanism in the dynamic switching process;

[0019] 3、The flexible joint and the ordinary rigid joint plus the flexible link robot leg transmission configuration of the application, the design of the foot cushioning and sensing module, the use of multistage cavity structure takes into account high and low frequency impact absorption, force sensor sensing feedback, provides data support for the landing decision in complex environment; BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 The overall structure diagram of the robot leg transmission configuration of the application is shown in the figure;

[0022] Figure 2 The motor module structure structure diagram of the driving and sensing integrated in the robot leg transmission configuration of the application is shown in the figure;

[0023] Figure 3 The flexible element structure diagram of the driving and sensing integrated motor module is shown in the figure;

[0024] Figure 4 The rigid and flexible collaborative connecting rod transmission module structure diagram in the robot leg transmission configuration of the application is shown in the figure;

[0025] Figure 5 The driving crank structure diagram in the rigid and flexible collaborative connecting rod transmission module is shown in the figure;

[0026] Figure 6 The driven crank structure and its connection mode between the driven crank and the lower leg in the rigid and flexible collaborative connecting rod transmission module are shown in the figure;

[0027] Figure 7 The foot cushioning structure diagram in the robot leg transmission configuration of the application is shown in the figure;

[0028] Figure 8 The parallel screw structure diagram in the rigid and flexible collaborative connecting rod transmission module is shown in the figure.

[0029] In the figure:

[0030] 1-Motor module integrating drive and perception 2-Rigid-flexible linkage transmission module 3-Foot cushioning 101-First Flexible Motor Joint Module 101a-first boss 101b-First Office 101c first rubber ring 101d-ring structure 102-Second flexible motor joint module 103-Ordinary rigid motor joint module 104-first joint connector 105-Second joint connector 201-Active crank 201a-Flexible link outer crank A 201b-Second rubber ring 201c-with crank A in flexible link 201d-Second boss 201e-third boss 201f-Second Office 201g-positioning piece 202-Thigh Shell 202a-Inner shell 202b-outer shell 203-Thigh connecting rod 204-driven crank 204a-Flexible link outer crank B 204b-Rectangular Connector A 205-calf 205a-Plastic layer 205b-carbon plate 301-conical shock absorbing cavity 302-Main buffer chamber 303-Support reinforcement cavity 303 304-Force Sensor 305-Rectangular Connector B DETAILED DESCRIPTION

[0032] In order to make the technical scheme of the application more clear and clear, the embodiment of the application is described in detail below with reference to the drawings. It should be noted that the following description is only one specific embodiment of the application, and does not limit the protection scope of the application.

[0033] like Figure 1 As shown in the figure, the transmission configuration of the robot leg, which combines flexible joints with conventional rigid joints and flexible links, mainly includes a motor module 1 that integrates drive and perception, a connecting rod transmission module 2 that combines rigidity and flexibility, and a foot cushioning module 3. These components are integrated in a modular manner, resulting in a compact structure and complementary functions, enabling comprehensive functions such as multi-degree-of-freedom drive, impact relief, real-time perception, and terrain adaptation.

[0034] like Figure 2 As shown, the drive and perception integrated motor module 1 includes a first flexible motor joint module 101, a second flexible motor joint module 102, a rigid motor joint module 103, a first joint connector 104 and a second joint connector 105, which are used to provide driving force for the legs and have high dynamic response and real-time torque perception functions.

[0035] Among them, the rigid motor joint module 103 is a medium to high power drive motor.

[0036] The first flexible motor joint module 101 and the second flexible motor joint module 102 have the same structure, both including an outer shell, a motor installed in the outer shell, a reducer and a flexible element. The output end of the motor is coaxially connected to the reducer and fixed to the input end of the outer shell. The reducer converts the high-speed and low-torque output of the motor into a low-speed and high-torque output. Figure 3 As shown, the flexible element is installed at the output end of the outer shell. The flexible element has a three-layer annular structure. The upper and lower annular structural members 101d have first bosses 101a arranged alternately in the circumferential direction. The middle layer is a first rubber ring 101c (or an elastomeric material such as silicone rubber or thermoplastic polyurethane) with multiple first actuators 101b in the circumferential direction. The first actuators 101b are the same height as the first bosses 101a and are respectively placed between adjacent first bosses 101a among all the first bosses 101a on the upper and lower annular structural members 101d, and are in contact with the opposite sides of the adjacent first bosses 101a.

[0037] The above-mentioned flexible element serves as the output end of the joint module, realizing the torsional elastic connection between the joint module and the load. In the flexible element, the lower annular structure 101d is connected to the output of the reducer; the end where the upper annular structure 101d is located is the output end, which is used to connect the load (joint module connection device, such as: a robotic arm or a robot leg connecting rod). Therefore, through the design of the flexible element, when the flexible motor joint module is subjected to impact or load, the first body 101b of the circumferential half of the first rubber ring 101c will be in a compressed state, and the remaining first petal 101b will be in a neutral state, forming a symmetrical strain response distribution, generating torsional elastic deformation, such as Figure 4As shown, the first flexible motor joint module 101 and the second flexible motor joint module 102 can produce slight elastic deformation when the joints are subjected to force, which can absorb external impact and protect the motor and reducer.

[0038] Two encoders are also installed at both ends of the above-mentioned flexible element. The encoder located at the output end of the flexible element is used to detect the angular change of the output end of the flexible element; the encoder at the other end is used to detect the angular change end of the reducer, thereby realizing the angular change monitoring between the upper and lower layers of the flexible element, so that the first flexible motor joint module 101 and the second flexible motor joint module 102 can output real-time torque signals.

[0039] The first joint connector 104 and the second joint connector 105 are respectively used to realize the connection between the first flexible motor module 101, the second flexible motor joint module 102 and the rigid motor joint module 103. Among them, the first joint connector 104 is an annular structure, and has a lug in the circumferential direction of the front end. The lug is connected to the circumferential end of the rigid motor joint module 103 shell by screws to achieve fixation between the two. The end of the first joint connector 104 has an annular boss for positioning the second joint connector 105. The second joint connector 105 has two parts, one part is a circular ring structure; the circular ring structure is sleeved on the annular boss at the end of the first joint connector 104, and is fixed to the end of the first joint connector 104 and the output end of the first flexible motor joint module 101 by screws evenly distributed circumferentially.

[0040] The other part of the second joint connector 105 is a circular connecting surface, which is arranged perpendicular to the plane where the annular boss is located, and is coaxially fixed to the output end of the flexible element in the second flexible motor joint module 102 through screws evenly distributed around the circumference.

[0041] The rigid-flexible linkage transmission module 2 is used to transmit joint driving force and coordinate the movement between joints. It adopts a parallel four-bar mechanism, including an active crank 201, a thigh shell 202, a thigh connecting rod 203, a driven crank 204 and a shank 205. Figure 4 shown.

[0042] Among them, the active crank 201 is also designed as a flexible structure, similar to the aforementioned flexible unit structure, including a flexible link outer crank A201a, a second rubber ring 201b and a flexible link inner crank A201c, which constitute a three-layer composite structure active crank 201. Figure 5 As shown. One end of the flexible link outer crank A201a is a large-diameter input end with a connection hole in the center. At the same time, three second bosses 201d are evenly designed around the circumference. The other end of the flexible link outer crank A201a is a small-diameter output end with a connection hole in the center.

[0043] The second rubber ring 201b (made of an elastomeric material such as silicone rubber or thermoplastic polyurethane) has an inner ring and six second operating bodies 201f designed circumferentially on the outer wall of the inner ring. The height of the second operating bodies 201f is equal to that of the second boss A201d.

[0044] The inner crank A201c of the flexible link is annular and made of 7075-T6 aluminum alloy, providing overall support strength. The inner side of the outer crank of the flexible link is evenly designed with three third bosses 201e, which have the same structure as the second bosses 201d.

[0045] The flexible link outer crank A201a, the second rubber ring 201b and the flexible link inner crank A203c are connected by staggered insertion of the three second bosses 201d at the input end of the flexible link outer crank A201a and the three third bosses 201e on the inner side of the flexible link inner crank A201c from both sides of the second rubber ring 201b between two adjacent second actuators 201f structures in the circumferential direction of the second rubber ring 201b; further, after the rotating shaft passes through the corresponding through holes at the input end of the flexible link outer crank 201 and the center of the flexible link inner crank A201c, it is connected to the flexible link outer crank 201 and the flexible link inner crank A201c via bearings to form a rotating pair; and after installation is completed, the left and right sides of each protruding structure are in contact with the opposite sides of the second actuators 201f on both sides.

[0046] The thigh shell 202 is composed of an inner shell and an outer shell that are interlocked. After the inner shell 202a and the outer shell 202b are interlocked, the two halves are fixed together by screws arranged circumferentially along the thigh shell 202. The active crank 201 is provided at the end of the thigh shell 202. The crank in the flexible link of the active crank 201 is fixedly connected to the output end of the rigid motor joint module 103 through the large circular hole provided in the inner shell 202a via screws evenly distributed circumferentially, forming a torsional elastic connection. At the same time, the thigh shell 202 is sleeved onto the annular boss designed on the output end of the rigid motor joint module 103 through the large circular hole to achieve the positioning of the thigh shell 202. It is then connected to the output end of the rigid motor joint module 103 through a circumferential screw and pin fastening method to ensure torsional stiffness and response speed.

[0047] The active crank 201 of the above structure can provide a certain degree of flexibility in the torsional direction of the joint during movement, effectively absorb the instantaneous impact caused by the undulation of the terrain, and realize the coordinated power transmission of rigidity and flexibility.

[0048] The thigh connecting rod 203, located within the thigh housing 202, is a straight rod with circular joints at both ends, each with coaxial through-holes. The distal end of the thigh connecting rod 203 is connected to the active crank 201 and is positioned between the output end of the flexible link outer crank and a positioning member 201g. After a rotating shaft passes through the positioning member 201g, the output end of the flexible link outer crank A201a, and the through-hole at the distal end of the thigh connecting rod, its two ends are connected to the positioning member 201g and the flexible link outer crank A201a via bearings, forming a revolute pair. The positioning member 201g is further secured to the input end of the flexible link outer crank A201a with screws, thereby enabling the connecting rod to rotate about the rotating axis.

[0049] The driven crank 204 is placed inside the front end of the housing and is a common rigid crank. The large diameter end of the driven crank 204 is sleeved on the rotating shaft, and the two ends of the rotating shaft are fixedly connected to the inner shell and the front end of the outer shell of the thigh housing 202; a rectangular joint 204a is designed on the outer wall of the large diameter end of the driven crank for connecting to the lower leg 205. Figure 6 The front end of the thigh connecting rod 203 and the small diameter end of the driven crank 204 are connected to the rotating shaft through a positioning piece B204b, and the connection method is the same as the connection method between the active crank 201 and the end of the thigh connecting rod 203.

[0050] The lower leg 205 is a three-layer structure, with a plastic layer 205a in the middle and carbon plates 205b on both sides.

[0051] The rectangular groove at the end of the plastic layer 205a is plugged into and positioned with the rectangular joint A204b on the outer wall of the output end of the driven crank 204, and the end of the carbon plate is fixedly connected to the rectangular protrusion by screws to achieve the fixation between the shank 205 and the driven crank 204.

[0052] The plantar cushioning 3 is a composite cushioning and sensing device installed at the front end of the calf 205, which is used to realize ground impact energy absorption and real-time contact force detection. The plantar cushioning 3 is a circular structure as a whole. In this embodiment, it is designed to be a circular sheet structure with a certain thickness. The top is designed to be a flat surface as a connecting surface. The plantar contact layer 301 contacts the ground in the circumferential direction, and the surface is designed with an anti-slip texture. At the same time, the plantar cushioning 3 adopts a chambered gas cushioning structure design, and the whole is made of rubber material through 3D printing. Figure 7 shown.

[0053] The divided-chamber gas buffer structure comprises:

[0054] ① The conical shock-absorbing cavity 301 at the lower inner portion of the sole cushion 3 is an inverted conical cavity arranged in the front-to-back direction, which can be compressed to absorb high-frequency impacts.

[0055] ② The main cushioning air chamber 302 at the front and rear positions inside the sole cushioning 3 can be filled with low-pressure inert gas (such as nitrogen) to absorb large-scale impact energy.

[0056] ③ The front and rear support reinforcement cavities 303 designed at the center position inside the plantar cushion 3 are filled with some hard plastic to enhance the anti-collapse capability of the plantar cushion 3 .

[0057] ④ The center groove of the connection surface of the plantar cushion 3 has a force sensor 304 with a diaphragm strain gauge structure installed on the inner bottom surface. It is connected to the main control unit via a flexible cable to achieve real-time monitoring of the ground contact status and data feedback. At the same time, a rectangular connector B305 is also installed in the groove. The bottom of the rectangular connector B305 is located in the groove, and there are lugs on both sides of the bottom. They are respectively inserted into the slots on both sides of the groove and positioned between the plantar cushion 3. The lugs are fixed to the plantar cushion 3 by screws, thereby fixing the rectangular connector 305 to the plantar cushion 3. In this way, the rectangular connector B305 is inserted and positioned with the rectangular groove at the front end of the plastic layer 205a in the calf 205, and the front end of the carbon plate is fixed to the rectangular connector B305 by screws. The connection between the plantar cushion 3 and the calf 205 is achieved.

[0058] In summary, the transmission configuration of the robot leg of the present invention is a combination of flexible joints and ordinary rigid joints plus flexible links, in which the first flexible motor joint module 101 and the second flexible motor joint module 102 in the motor module 1 with integrated drive and perception are embedded with designed flexible elements and encoders at both ends, which can realize real-time measurement of output torque and impact relief function between joints; the rigid module provides high-power and high-precision driving force output.

[0059] At the same time, the connecting rod transmission module with rigid-flexible coordination capability is composed of a symmetrical parallel four-bar structure consisting of an active crank 201, a thigh connecting rod 203, and a driven crank 204, such as Figure 8 As shown; wherein, the active crank 201 is driven by the output of the rigid motor joint module 103; and the active crank 201 and the driven crank 204 adopt a three-layer composite structure (aluminum alloy + elastomer + aluminum alloy), which can achieve flexible mechanical response and motion coordination while maintaining the overall structural strength, effectively solve the impact concentration and power unevenness problems of rigid structures in irregular terrain, and realize the dynamic unity of force transmission and flexible adaptation.

[0060] Furthermore, the designed plantar cushioning and sensing module has a multi-level cavity structure and an integrated high-sensitivity force sensor, which can absorb high-frequency impact energy at the moment of landing, provide real-time feedback for gait switching, terrain recognition and stability control, and greatly improve the robot's landing stability and environmental perception capabilities on complex terrain.

[0061] The flexible joints of this invention connect to each module in the transmission configuration of a conventional rigid joint plus a flexible link in a robotic leg through standardized mechanical connectors and electrical interfaces. This allows for scalability to multiple platforms, such as tripod, quadruped, or hexapod robotic lower limb systems, as needed. Its modular design provides strong scalability, maintainability, and task adaptability. This structure is particularly suitable for applications such as outdoor mobility in complex terrain, high-dynamic response tasks, high-impact environments, and the need for compliant interaction in human-robot collaboration.

Claims

1. A transmission configuration of a robot leg comprising a flexible joint and a conventional rigid joint plus a flexible link, characterized by: It includes a motor module integrating drive and perception, a rigid-flexible linkage transmission module, and a sole cushioning system. The drive and perception integrated motor module includes a first flexible motor joint module, a second flexible motor joint module, a rigid motor joint module and a joint connector; Among them, the rigid motor joint module is a driving motor; the first flexible motor joint module and the second flexible motor joint module have the same structure, both including an outer shell, a motor installed in the outer shell, a reducer and a flexible element; the motor output end is coaxially connected to the reducer and fixed to the input end of the outer shell; the flexible element is installed at the input end of the outer shell and connected to the output end of the reducer to achieve a torsional elastic connection with the load; Two encoders are also installed at both ends of the flexible element, wherein the encoder at the output end of the flexible element is used to detect the angle change of the output end of the flexible element; the encoder at the other end is used to detect the angle change end of the reducer, thereby realizing the angle change monitoring between the upper and lower layers of the flexible element; thereby, the first flexible motor joint module and the second flexible motor joint module can output real-time torque signals. The joint connector is used to realize the connection between the first flexible motor module, the second flexible motor joint module and the rigid motor joint module, including a coaxial connection between the end of the rigid motor joint module housing and the output end of the outer shell of the first flexible motor joint module, and a connection of the second flexible motor joint module, and the axis of the second flexible motor joint module is perpendicular to the axis of the rigid motor joint module; The rigid-flexible linkage transmission module is used to transmit joint driving force and coordinate the movement between joints. It adopts a parallel four-bar mechanism, including an active crank, a thigh shell, a thigh connecting rod, a driven crank and a shank. Among them, the end of the active crank is a flexible structure, fixedly installed on the output end of the rigid motor joint module, realizing a torsional elastic connection between the two, so that the active crank provides flexibility in the torsion direction of the joint during movement; the front end of the active crank is connected to the end of the thigh connecting rod to form a revolving pair; the front end of the thigh connecting rod is connected to the front end of the driven crank to form a revolving pair; the end of the driven crank is designed with a plug, which is plugged and fixed to the end of the calf; the front end of the calf is plugged and fixed to the sole cushion; The above-mentioned active crank, thigh connecting rod and driven crank are located in the thigh shell. The end of the thigh shell is fixedly connected to the end of the rigid motor joint module body, and the front end is connected to the end of the driven crank to form a rotating pair.

2. The transmission configuration of a robot leg comprising a flexible joint, a common rigid joint and a flexible link as claimed in claim 1, characterized in that: The flexible element has a three-layer annular structure, which is circumferentially coordinated by the bosses designed on the upper and lower layers and the valves designed on the circumference of the middle layer of elastomeric material. The specific coordination method is: the bosses on the circumference of the upper annular structure are arranged in an alternating manner, and the valves on the circumference of the middle layer are respectively placed between adjacent bosses among all the bosses on the upper and lower annular structural parts, and fit with the opposite sides of the adjacent bosses; thus, when the flexible link is subjected to torque, it will deform, and the valves on the circumference of the middle layer will be in a compressed state, while the remaining valves will be in a neutral state.

3. The transmission configuration of a robot leg comprising a flexible joint, a common rigid joint and a flexible link as claimed in claim 1, characterized in that: The joint connector includes a first joint connector and a second joint connector; wherein the first joint connector is an annular structure, and has a lug on the circumferential direction of the front end fixedly connected to the end of the rigid motor joint module housing; the end of the first joint connector has an annular boss for positioning the second joint connector; the second joint connector has two parts, one part is a circular ring structure that is sleeved on the annular boss at the end of the first joint connector, and is fixedly connected to the end of the first joint connector and the output end of the first flexible motor joint module through circumferentially distributed screws; the other part of the second joint connector is a circular connecting surface, which is arranged perpendicular to the plane where the annular boss is located, and the output end of the second flexible motor joint module is fixed on the circular connecting surface.

4. The transmission configuration of a robot leg comprising a flexible joint, a common rigid joint and a flexible link as claimed in claim 1, characterized in that: The active crank is a three-layer composite structure active crank consisting of an outer crank of a flexible link, an intermediate ring of elastomeric material and an inner crank of a flexible link; bosses are evenly designed on the circumference of the end of the outer crank of the flexible link and the inner crank of the flexible link, and the bosses on the two are arranged alternately; actuators are evenly designed on the circumference of the intermediate ring, and are placed between adjacent bosses among all the bosses on the upper and lower annular structural parts, and fit with the opposite sides of the adjacent bosses; as a result, when the end of the active crank is subjected to torque, the actuator part of the circumference of the intermediate ring is in a compressed state, and the remaining petals are in a neutral state.

5. The transmission configuration of a robot leg comprising a flexible joint, a common rigid joint and a flexible link as claimed in claim 1, characterized in that: The lower leg is a three-layer structure, with a plastic layer in the middle and carbon plates on both sides. The plastic layer has rectangular grooves at both ends. The rectangular grooves at the ends of the plastic layer mate with the joint at the end of the driven crank, and screws secure the carbon plate end to the joint.

6. The transmission structure of a robot leg comprising a flexible joint, a common rigid joint and a flexible link as claimed in claim 1, characterized in that: The plantar cushioning system is circular in structure and adopts a split-chamber gas cushioning structure design, including: a conical shock-absorbing chamber at the lower part of the plantar cushioning system, which is an inverted conical chamber arranged along the front-to-back direction; two front and rear support reinforcement chambers designed at the center of the plantar cushioning system, which are filled with hard plastic; a force sensor is set on the bottom surface of the center groove of the plantar cushioning connection surface; at the same time, a joint is installed in the groove to plug into the bottom of the plantar cushioning system to fix the plantar cushioning system.

7. The transmission structure of a robot leg comprising a flexible joint, a common rigid joint and a flexible link as claimed in claim 1, characterized in that: The sole contact layer of the foot cushioning is in contact with the ground around the foot, and the surface is designed with anti-slip texture.

8. The transmission structure of a robot leg comprising a flexible joint, a common rigid joint and a flexible link as claimed in claim 1, characterized in that: The main cushioning air chambers at the front and rear positions inside the sole cushioning are filled with low-pressure inert gas.

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