Bionic biped robot with variable-rigidity joints and double-joint flexibility

Abstract

The invention discloses a bionic biped robot with variable rigidity joints and double-joint flexibility, which comprises a trunk, thighs, variable rigidity knee joints, shanks and feet, and the double-joint flexible part of each leg is driven by three elastic drivers connected in series; a front-side linear motor of the rigidity-variable knee joint is rotationally connected to a mounting frame at the lower end of the thigh, and an output shaft of the front-side linear motor is connected with one end of an L-shaped connecting piece; the rear-side linear motor is mounted on the mounting frame, an output shaft of the rear-side linear motor is sequentially sleeved with a rear-side shell, a rear-side spring and a front-side shell and then fixed to the output end connecting piece, and the two sides of the rear-side spring make contact with the rear-side shell and the output end connecting piece respectively; a rope is led out from the tail end of the front side shell, is wound on a rear side shaft and a knee joint shaft in sequence, penetrates through two pairs of rollers and is fixed on a knee joint output shaft; the rollers are installed at the other ends of the L-shaped connecting pieces, and the knee joint shaft is connected with the switching parts of the two L-shaped connecting pieces through bearings. The robot has good stability, flexibility and adaptability.

Description

Technical Field

[0001] The invention belongs to the technical field of robots, and in particular relates to a bionic biped robot with variable stiffness joints and double-joint flexibility. Background Art

[0002] Organisms in nature exhibit amazing environmental adaptability and are able to perform a variety of tasks in a changing environment. This adaptability is largely due to the collaborative work of the muscle and joint systems, which can adjust stiffness in real time to adapt to different movement requirements. Specifically, when the joints perform movement tasks that require stability and large force output (such as jumping into the air), they can increase stiffness by adjusting muscles; when the joints perform movement tasks that require shock absorption and energy storage (such as landing from the air), they can reduce stiffness by adjusting muscles. This dynamic regulation mechanism is the result of highly complex and precise regulation of biological movement systems. Inspired by this natural animal muscle and joint stiffness regulation mechanism, researchers invented a variable stiffness actuator.

[0003] Most of the joints of traditional biped robots use rigid actuators, which have the characteristics of simple control, high precision and infinite theoretical stiffness. With the development of robot technology, traditional rigid actuators can no longer meet the needs. For example, various impacts often occur when the robot moves, and there is no energy absorption and buffering structure in the rigid actuator. The instantaneous impact force can easily cause damage to the structure of the robot. Introducing variable stiffness actuators in biped robots can effectively solve these problems. Variable stiffness actuators can make joint movements smoother, not only preventing hardware damage caused by impact, but also continuously storing and releasing energy during the robot's walking process to achieve higher energy efficiency. However, compared with traditional rigid actuators, variable stiffness actuators require additional stiffness adjustment motors, so they usually have more mechanical components and control elements, which increases the total weight and complexity of the system. In addition, the design and configuration of elastic elements in variable stiffness actuators have a crucial impact on the overall energy storage effect of variable stiffness actuators, further increasing the difficulty and requirements of the design.

[0004] In addition to the influence of single-joint flexibility on human movement, bi-articular muscles also play an extremely important role in the movement process. Bi-articular muscles refer to muscles that span two or more joints, which can provide complex and fine regulation capabilities for human movement. When the human body performs jumping movements, bi-articular muscles ensure the stability of movement and realize energy recycling by coordinating the movements of different joints. By introducing structures inspired by bi-articular muscles into robots, the robot's adaptability to complex environments and dynamic stability can be greatly improved, and the robot's movement gait can also be made more natural. Summary of the invention

[0005] In view of this, the present invention provides a bionic biped robot with variable stiffness joints and double-joint flexibility.

[0006] The present invention achieves the above technical objectives through the following technical means.

[0007] A bionic biped robot with variable stiffness joints and double-joint flexibility, comprising:

[0008] A trunk, 4 trunk linear motors, 2 hip joint motors and 2 synchronous belt pinions; the 4 trunk linear motors are divided into two groups, front and rear, the output shafts of the front group of trunk linear motors are respectively connected to one end of two span double-joint springs A, and the output shafts of the rear group of trunk linear motors are respectively connected to one end of two span double-joint springs B; the output shafts of the hip joint motors are connected to the synchronous belt pinions;

[0009] The thigh includes a thigh linear motor and a terminal connector, a synchronous belt gear and a synchronous belt; the synchronous belt gear is fixed between the upper ends of the thigh outer baffle and the inner thigh baffle, and the inner part of the synchronous belt gear is interference fit with the outer end of the hip joint shaft, and the outer side of the synchronous belt gear is connected to the synchronous belt pinion through the synchronous belt; the thigh linear motor is installed at the lower part of the thigh outer baffle;

[0010] A variable stiffness knee joint comprises a posterior linear motor of the knee joint, a posterior spring of the knee joint, a knee output rope, a knee output end roller, a knee output end baffle, a knee L-shaped connector and a front linear motor of the knee joint; the posterior linear motor of the knee joint is mounted on a knee linear motor mounting frame located between the lower ends of the outer thigh baffle and the inner thigh baffle; the output shaft of the posterior linear motor of the knee joint is sequentially sleeved with a posterior shell of the posterior spring of the knee joint, a posterior spring of the knee joint and a front shell of the posterior spring of the knee joint, and then fixed to the output end connector of the posterior linear motor of the knee joint; the rear shell of the posterior spring of the knee joint and the front shell of the posterior spring of the knee joint are connected together by screws; the two sides of the posterior spring of the knee joint are respectively in contact with the rear shell of the posterior spring of the knee joint and the output end connector of the posterior linear motor of the knee joint; the posterior axis of the knee joint is interference-connected on the knee linear motor mounting frame near the front shell of the posterior spring of the knee joint; One end of the knee joint linear motor mounting frame close to the calf is rotatably connected to the knee joint shaft, and the knee joint shaft is rotatably connected to the transition part of the two knee joint L-shaped connecting pieces, and two pairs of knee joint output end rollers are installed on the part of the knee joint L-shaped connecting piece along the calf direction; after the two ends of the knee joint shaft pass through the knee joint linear motor mounting frame, they are rotatably connected to the two ends of the U-shaped knee joint output end baffle; the knee joint output end baffle is close to the knee joint output end roller, and is interference connected to the knee joint output shaft; the rear end of the front side shell of the knee joint rear spring leads out the knee joint output rope, which is successively wound around the knee joint rear side shaft and the knee joint shaft, and then passes through the two pairs of knee joint output end rollers, and is finally fixed on the knee joint output shaft; the ends of the other parts of the two knee joint L-shaped connecting pieces are connected to the output shaft of the front side linear motor of the knee joint, and the front side linear motor of the knee joint is rotatably connected to the front side linear motor mounting base of the knee joint, and the front side linear motor mounting base of the knee joint is installed on the knee joint linear motor mounting frame;

[0011] The calf and foot include a calf connecting rod and an ankle joint motor; the bottom end of the calf connecting rod is rigidly connected to the housing of the ankle joint motor, the output shaft of the ankle joint motor is connected to the outer side and bottom side baffle of the foot, and the outer side and bottom side baffle of the foot are rigidly connected to the inner side baffle of the foot; the top end of the calf connecting rod is fixed to the end of the knee joint output end baffle;

[0012] The cross-double-joint spring A and the cross-double-joint spring B are wound around the boss on the inner thigh baffle and then fixed on the boss on the inner side of the knee joint output end baffle; the output shaft of the thigh linear motor is connected to one end of the cross-double-joint spring C, and the cross-double-joint spring C is wound around the boss on the outer side of the knee joint output end baffle and then fixed on the boss on the outer side of the foot and the outer side of the bottom baffle.

[0013] In the above technical solution, a synchronous belt pinion housing is provided on the outer side of the synchronous belt pinion, and the outer side of the synchronous belt pinion housing is rotatably connected to the synchronous belt pretensioner. The end of the synchronous belt pretensioner is interference-connected to the synchronous belt pretensioner shaft and roller. The synchronous belt pretensioner shaft and roller include a pretensioner shaft and a roller. The pretensioner shaft is connected to the end of the synchronous belt pretensioner, and a roller is sleeved on the pretensioner shaft, and the roller is in contact with the synchronous belt.

[0014] In the above technical solution, the hip joint motor is installed inside the hip joint motor housing, the bottom of the hip joint motor housing is connected to the trunk connecting piece, and the lower end of the trunk connecting piece is fixed on the hip joint axis.

[0015] In the above technical solution, a hip joint shaft end screw and a gasket are installed at the end of the hip joint shaft.

[0016] In the above technical solution, an inner shell plate of the hip joint motor is connected between the two hip joint motor shells, and a groove for placing the hip joint motor is formed on the inner shell plate of the hip joint motor.

[0017] In the above technical solution, the synchronous belt pinion housing and the hip joint motor housing are both connected to the outer housing plate of the hip joint motor.

[0018] In the above technical solution, the operation of the trunk linear motor, hip joint motor, thigh linear motor, ankle joint motor, posterior knee joint linear motor, and anterior knee joint linear motor are respectively controlled by STM32 control boards, and multiple STM32 control boards communicate with the industrial computer.

[0019] In the above technical solution, an electronic component placement plate is arranged on the upper part of the hip joint motor housing for placing an industrial computer, an STM32 control board and a battery, and the battery provides power for the industrial computer and the STM32 control board.

[0020] In the above technical solution, the trunk linear motor is installed in a trunk linear motor installation box, and the top of the trunk linear motor installation box is connected to the trunk shell.

[0021] In the above technical solution, the boss on the inner side of the baffle at the output end of the knee joint is provided with two annular grooves.

[0022] The beneficial effects of the present invention are:

[0023] (1) The variable stiffness knee joint in the present invention adopts a compact structural design, which effectively reduces the overall weight and volume and improves the integration of the system; the configuration of the spring on the back of the thigh ensures the overall energy storage and release capabilities of the driver; and the knee joint balance position adjustment motor (linear motor on the front of the knee joint) and the stiffness adjustment motor (linear motor on the back of the knee joint) are independently controllable, ensuring that the knee joint has excellent variable stiffness effect even in an unbalanced position.

[0024] (2) The knee joint structure designed by the present invention not only has the ability to adjust joint stiffness in real time, but also combines the characteristics of dual-joint flexibility, significantly improving bionics and motion adaptability. This design not only optimizes the flexibility and adaptability of motion control, but also provides a wider potential for the application of bipedal robots in diverse environments, making them significantly superior to robots with traditional rigid drives or fixed-stiffness series elastic drives in terms of stability and efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is the overall assembly diagram of the bionic biped robot of the present invention;

[0026] Figure 2 This is an assembly diagram of the right leg of the bionic biped robot of the present invention;

[0027] Figure 3 is a cross-sectional view of the trunk of the present invention;

[0028] Figure 4 This is an assembly diagram of the thigh of the present invention;

[0029] Figure 5 It is an assembly diagram of the lower leg and foot of the present invention;

[0030] Figure 6 is a cross-sectional view of the variable stiffness knee joint of the present invention;

[0031] In the figure: 1-trunk, 2-thigh, 3-variable stiffness knee joint, 4-calf and foot, 5-cross-double joint spring A, 6-cross-double joint spring B, 7-cross-double joint spring C, 8-trunk linear motor mounting box, 9-trunk linear motor and end connector, 10-hip joint motor housing, 11-trunk housing, 12-trunk connector, 13-hip joint shaft, 14-hip joint shaft end screw and gasket, 15-synchronous belt preload shaft and roller, 16-synchronous belt preload, 17-hip joint motor outer shell plate, 18-synchronous belt pinion, 19-hip joint motor base, 20-hip joint motor shaft connector, 21-hip joint motor, 22-synchronous belt pinion housing, 23-hip joint motor inner shell plate, 24-electronic component placement plate, 25-thigh outer baffle, 26-thigh linear motor installation Box, 27-thigh linear motor and end connector, 28-inner thigh baffle, 29-synchronous belt large gear, 30-synchronous belt, 31-calf connecting rod, 32-outer and bottom baffles of the foot, 33-inner baffle of the foot, 34-ankle motor, 35-knee linear motor mounting frame, 36-posterior linear motor of the knee joint, 37-posterior shell of the rear spring of the knee joint, 38-posterior spring of the knee joint, 39-posterior linear motor output end connector of the knee joint, 40-posterior spring of the knee joint front shell, 41-posterior shaft of the knee joint, 42-knee output rope, 43-knee shaft, 44-knee output end roller, 45-knee output shaft, 46-knee output end baffle, 47-knee L-shaped connector, 48-anterior linear motor of the knee joint, 49-anterior linear motor mounting base of the knee joint. DETAILED DESCRIPTION

[0032] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments, but the protection scope of the present invention is not limited thereto.

[0033] The present invention designs a bionic biped robot with variable stiffness joints and double-joint flexibility, which has a symmetrical structure as a whole. The robot consists of a trunk 1, a thigh 2, a variable stiffness knee joint 3, a calf and a foot 4, wherein the number of thighs 2, variable stiffness knee joints 3, calves and feet 4 is 2. The double-joint flexible part of each leg is driven by three series elastic drivers, and the series elastic driver is composed of a spring and a corresponding linear motor. Specifically, the cross-double-joint spring A5, the cross-double-joint spring B6 and its corresponding motors respectively simulate the rectus femoris and hamstring muscles of the human thigh to achieve flexible coupling of the hip and knee joints, and the cross-double-joint spring C7 and its corresponding motor simulate the gastrocnemius muscle of the human calf to achieve flexible coupling of the knee and ankle joints. Figure 2 shown.

[0034] like Figure 3As shown, the trunk 1 includes 4 trunk linear motors and end connectors 9, 2 hip joint motors 21 and 2 synchronous belt pinions 18; the trunk linear motor and end connector 9 include two parts, the trunk linear motor and the end connector, the end connector is connected to the output shaft of the trunk linear motor, the trunk linear motor is installed in the trunk linear motor mounting box 8, the top of the trunk linear motor mounting box 8 is connected to the trunk shell 11, and the trunk shell 11 is located at the outermost side of the entire trunk 1; the 4 trunk linear motors are divided into two groups, front and back, the end connectors of the front group of trunk linear motors are respectively connected to one end of the two-span double-joint springs A5, and the end connectors of the rear group of trunk linear motors are respectively connected to one end of the two-span double-joint springs B6; the inner side of the trunk linear motor mounting box 8 is fixedly connected to one side of the hip joint motor housing 10, the hip joint motor 21 is connected to the inside of the hip joint motor housing 10 through the hip joint motor base 19, and the output shaft of the hip joint motor 21 is connected to the synchronous belt pinion 18 through the hip joint motor shaft connector 20; the synchronous belt pinion A synchronous belt pinion housing 22 is provided on the outer side of 18, and the synchronous belt pinion housing 22 and the hip joint motor housing 10 are both connected to the outer housing plate 17 of the hip joint motor, and an inner housing plate 23 of the hip joint motor is connected between the two hip joint motor housings 10, and a groove for placing the hip joint motor 21 is provided on the inner housing plate 23 of the hip joint motor; the lower parts of the two hip joint motor housings 10 are both connected to the trunk connecting piece 12, and the lower end of the trunk connecting piece 12 is provided with a through hole passing through the hip joint shaft 13, and the lower end of the trunk connecting piece 12 is connected to the hip joint shaft 13. The joint shafts 13 do not rotate relative to each other; an electronic component placement plate 21 is arranged on the upper part of the two hip joint motor housings 10, which is used to place an industrial computer, an STM32 control board, and a battery, and the battery supplies power to the industrial computer and the STM32 control board; the outer side of the synchronous belt pinion housing 22 is rotatably connected to the synchronous belt pretensioner 16, and the end of the synchronous belt pretensioner 16 is interference-connected to the synchronous belt pretensioner shaft and roller 15, and the pretensioner shaft and roller 15 include a pretensioner shaft and a roller, and the roller is sleeved on the pretensioner shaft, and the pretensioner shaft is connected to the end of the synchronous belt pretensioner 16.

[0035] like Figure 4 As shown, the thigh 2 includes a thigh linear motor and an end connector 27, a synchronous belt gear 29 and a synchronous belt 30. The synchronous belt gear 29 is fixed between the upper ends of the thigh outer baffle 25 and the inner thigh baffle 28. The interior of the synchronous belt gear 29 is interference fit with the outer end of the hip joint shaft 13 through a bearing. The end of the hip joint shaft 13 is equipped with a hip joint shaft end screw and a gasket 14 to prevent the thigh 2 from detaching; the synchronous belt gear 29 is connected to the synchronous belt pinion 18 through the synchronous belt 30, and the roller is in contact with the synchronous belt 30 to adjust the preload force of the synchronous belt; a thigh linear motor mounting box 26 is fixedly connected to the lower part of the thigh outer baffle 25, and a thigh linear motor is mounted inside the thigh linear motor mounting box 26.

[0036] like Figure 5 As shown, the calf and foot 4 includes a calf connecting rod 31 and an ankle joint motor 34, the bottom end of the calf connecting rod 31 is rigidly connected to the housing of the ankle joint motor 34, the output shaft of the ankle joint motor 34 is connected to the outer side and bottom side baffle 32 of the foot, the outer side and bottom side baffle 32 of the foot is rigidly connected to the inner side baffle 33 of the foot, and the outer side and bottom side baffle 32 of the foot and the inner side baffle 33 of the foot are both sleeved on the housing of the ankle joint motor 34. A boss with an annular groove is arranged on the outer side of the outer side and bottom side baffle 32 of the foot, which is used to fix one end of the cross-double joint spring C7.

[0037] like Figure 6As shown, the variable stiffness knee joint 3 includes a knee joint rear linear motor 36, a knee joint rear spring 38, a knee joint output rope 42, a knee joint output end roller 44, a knee joint output end baffle 46, a knee joint L-shaped connector 47 and a knee joint front linear motor 48. The knee joint rear linear motor 36 is mounted on a knee joint linear motor mounting frame 35, and the knee joint linear motor mounting frame 35 is connected between the lower ends of the thigh outer baffle 25 and the inner thigh baffle 28. The output shaft of the knee joint rear linear motor 36 is fixed to the knee joint rear linear motor output end connector 39, and the knee joint rear linear motor output end connector 39 contacts one side of the knee joint rear spring 38. The knee joint rear spring 38 is sleeved on the output shaft of the knee joint rear linear motor 36, and the other side of the knee joint rear spring 38 is fixed to the lower end of the knee joint rear linear motor 36. The side contacts the rear shell 37 of the rear spring of the knee joint; the rear shell 37 of the rear spring of the knee joint is connected to the front shell 40 of the rear spring of the knee joint by screws, and the distance between the two is adjustable; the rear shaft 41 of the knee joint is interference-connected on the front shell 40 of the rear spring of the knee joint; the end of the knee joint linear motor mounting frame 35 close to the calf is connected to the knee joint shaft 43 through a bearing, and the knee joint shaft 43 is connected to the transition part of the two knee joint L-shaped connecting pieces 47 through a bearing, and the knee joint L-shaped connecting piece 4 Two pairs of knee joint output rollers 44 are installed on the part along the calf direction, and a pair of knee joint output rollers 44 close to the calf are processed with grooves to facilitate the routing of the knee joint output rope 42; after the two ends of the knee joint shaft 43 pass through the knee joint linear motor mounting frame 35, they are connected to the two ends of the U-shaped knee joint output end baffle 46 through bearings, and the knee joint output end baffle 46 is close to the knee joint output roller 44, and is interference connected to the knee joint output shaft 45; the rear end of the front shell 40 of the knee joint rear spring leads out the knee joint output rope 42, according to It is wrapped around the posterior axis 41 and the knee axis 43 of the knee joint, then passes through two pairs of rollers 44 at the output end of the knee joint, and is finally fixed on the output axis 45 of the knee joint; the end of the baffle 46 at the output end of the knee joint is fixed to the top of the calf connecting rod 31; the ends of the other parts of the two knee joint L-shaped connecting parts 47 are connected to the output axis of the front linear motor 48 of the knee joint, and the front linear motor 48 of the knee joint is rotatably connected to the front linear motor mounting base 49 of the knee joint, and the front linear motor mounting base 49 of the knee joint is installed on the knee linear motor mounting frame 35.

[0038] The inner and outer sides of the knee joint output end baffle 46 are respectively provided with bosses with annular grooves, and the inner boss is provided with two annular grooves. The inner thigh baffle 28 is also provided with a boss with two annular grooves. Figure 1The cross-double joint spring A5 and the cross-double joint spring B6 are wound around the boss on the inner thigh baffle 28 and fixed to the boss on the inner side of the knee joint output end baffle 46. One end of the cross-double joint spring C7 is connected to the output shaft of the thigh linear motor, and is wound around the boss on the outer side of the knee joint output end baffle 46 and fixed to the boss on the outer side of the foot and the outer side of the bottom baffle 32.

[0039] The operations of the trunk linear motor, hip joint motor 21, thigh linear motor, ankle joint motor 34, knee joint posterior linear motor 36, and knee joint anterior linear motor 48 are respectively controlled by STM32 control boards, and multiple STM32 control boards communicate with the industrial computer.

[0040] The working principle of the bionic biped robot with variable stiffness joints and double-joint flexibility of the present invention is as follows: the hip joint motor 21 located in the upper body drives the synchronous belt pinion 18 to rotate through the hip joint motor shaft connector 20, and the synchronous belt pinion 18 drives the synchronous belt large gear 29 to rotate through the synchronous belt 30, thereby realizing the control of the hip joint; the front side linear motor 48 of the knee joint can control the knee joint L-shaped connector 47 to rotate around the knee joint axis 43 through telescopic movement, thereby realizing the control of the balance position of the variable stiffness knee joint 3, and the rear side linear motor 36 of the knee joint can control the rotation of the knee joint L-shaped connector 47 ... thereby realizing the control of the balance position of the variable stiffness knee joint 3, thereby realizing the control of the balance position of the variable stiffness knee joint 3, thereby realizing the control of the balance position of the variable stiffness knee joint 3, thereby realizing the control Through extension and retraction, the position of the output end connector 39 of the rear linear motor of the knee joint can be controlled, which affects the preload degree of the rear spring 38 of the knee joint. The spring force of the rear spring 38 of the knee joint is transmitted to the output rope 42 of the knee joint through the rear shell 37 of the rear spring of the knee joint and the front shell 40 of the rear spring of the knee joint. The rope force of the output rope 42 of the knee joint is equal to the spring force. Therefore, by controlling the extension and retraction of the rear linear motor 36 of the knee joint, the stiffness of the variable stiffness knee joint 3 can be controlled; the ankle joint is directly driven by the ankle motor 34. In addition, by controlling the extension and retraction of the linear motors corresponding to the cross-double joint spring A5, the cross-double joint spring B6, and the cross-double joint spring C7, the preload force of the cross-double joint spring is changed, and the passive flexible coupling force between the hip-knee joint and the knee-ankle joint is further adjusted.

[0041] The embodiments are preferred implementations of the present invention, but the present invention is not limited to the above-mentioned implementations. Any obvious improvements, substitutions or modifications that can be made by those skilled in the art without departing from the essential content of the present invention belong to the protection scope of the present invention.

Claims

1. A bionic biped robot with variable stiffness joints and double joint flexibility, characterized in that: include: A trunk (1), four trunk linear motors, two hip joint motors (21) and two synchronous belt pinions (18); the four trunk linear motors are divided into two groups, front and rear, the output shafts of the front group of trunk linear motors are respectively connected to one end of two span double joint springs A (5), and the output shafts of the rear group of trunk linear motors are respectively connected to one end of two span double joint springs B (6); the output shaft of the hip joint motor (21) is connected to the synchronous belt pinion (18); The thigh (2) comprises a thigh linear motor and an end connector (27), a synchronous belt gear (29) and a synchronous belt (30); the synchronous belt gear (29) is fixed between the upper ends of the thigh outer baffle (25) and the inner thigh baffle (28), and the inner part of the synchronous belt gear (29) is interference fit with the outer end of the hip joint shaft (13), and the outer side of the synchronous belt gear (29) is connected to the synchronous belt pinion (18) through the synchronous belt (30); the thigh linear motor is installed at the lower part of the thigh outer baffle (25); A variable stiffness knee joint (3) comprises a knee joint rear linear motor (36), a knee joint rear spring (38), a knee joint output rope (42), a knee joint output end roller (44), a knee joint output end baffle (46), a knee joint L-shaped connecting piece (47) and a knee joint front linear motor (48); the knee joint rear linear motor (36) is mounted on a knee joint linear motor mounting frame (35) located between the lower ends of a thigh outer baffle (25) and a thigh inner baffle (28); a knee joint rear spring rear shell (37) is sequentially sleeved on the output shaft of the knee joint rear linear motor (36); ), a knee joint rear spring (38) and a knee joint rear spring front shell (40), and then fixed to a knee joint rear linear motor output end connector (39); the knee joint rear spring rear shell (37) and the knee joint rear spring front shell (40) are connected together by screws; the two sides of the knee joint rear spring (38) are respectively in contact with the knee joint rear spring rear shell (37) and the knee joint rear linear motor output end connector (39); a knee joint rear shaft (41) is interference-connected on the knee joint linear motor mounting frame (35) near the knee joint rear spring front shell (40); the knee joint rear spring rear shell (37) and the knee joint rear linear motor output end connector (39) are respectively in contact with the knee joint rear spring rear shell (37) and the knee joint rear linear motor output end connector (39); the knee joint rear spring rear shell (40) is connected to the knee joint rear linear motor mounting frame (35) by interference; The end of the joint linear motor mounting frame (35) close to the calf is rotatably connected to the knee joint shaft (43), and the knee joint shaft (43) is rotatably connected to the transition part of two knee joint L-shaped connecting pieces (47), and two pairs of knee joint output end rollers (44) are installed on the part of the knee joint L-shaped connecting piece (47) along the calf direction; after the two ends of the knee joint shaft (43) pass through the knee joint linear motor mounting frame (35), they are rotatably connected to the two ends of the U-shaped knee joint output end baffle (46); the knee joint output end baffle (46) is close to the knee joint output end roller (44) and is interference connected to the knee joint output shaft (45); A knee joint output rope (42) is led out from the rear end of the front shell (40) of the rear spring, and is sequentially wound around the rear shaft (41) and the knee shaft (43), and then passes through two pairs of knee joint output end rollers (44), and is finally fixed on the knee joint output shaft (45); the ends of the other parts of the two knee joint L-shaped connectors (47) are connected to the output shaft of the front linear motor (48) of the knee joint, and the front linear motor (48) of the knee joint is rotatably connected to the front linear motor mounting base (49) of the knee joint, and the front linear motor mounting base (49) of the knee joint is mounted on the knee joint linear motor mounting frame (35); The calf and foot (4) include a calf connecting rod (31) and an ankle joint motor (34); the bottom end of the calf connecting rod (31) is rigidly connected to the housing of the ankle joint motor (34); the output shaft of the ankle joint motor (34) is connected to the outer side and bottom side baffles (32) of the foot; the outer side and bottom side baffles (32) of the foot are rigidly connected to the inner side baffles (33) of the foot; the top end of the calf connecting rod (31) is fixed to the end of the knee joint output end baffle (46); The cross-double-joint spring A (5) and the cross-double-joint spring B (6) are wound around the boss on the inner thigh baffle (28) and then fixed on the boss on the inner side of the knee joint output end baffle (46); the output shaft of the thigh linear motor is connected to one end of the cross-double-joint spring C (7), and the cross-double-joint spring C (7) is wound around the boss on the outer side of the knee joint output end baffle (46) and then fixed on the boss on the outer side of the foot and the outer side of the bottom baffle (32).

2. The bionic biped robot with variable stiffness joints and double joint flexibility according to claim 1, characterized in that: A synchronous belt pinion housing (22) is provided on the outer side of the synchronous belt pinion housing (22), and the outer side of the synchronous belt pinion housing (22) is rotatably connected to the synchronous belt pretensioner (16). The end of the synchronous belt pretensioner (16) is interference-connected to the synchronous belt pretensioner shaft and roller (15). The synchronous belt pretensioner shaft and roller (15) include a pretensioner shaft and a roller. The pretensioner shaft is connected to the end of the synchronous belt pretensioner (16), and a roller is sleeved on the pretensioner shaft. The roller is in contact with the synchronous belt (30).

3. The bionic biped robot with variable stiffness joints and double joint flexibility according to claim 2, characterized in that: The hip joint motor (21) is installed inside the hip joint motor housing (10), the bottom of the hip joint motor housing (10) is connected to the trunk connecting piece (12), and the lower end of the trunk connecting piece (12) is fixed on the hip joint shaft (13).

4. The bionic biped robot with variable stiffness joints and double joint flexibility according to claim 1, characterized in that: A hip joint shaft end screw and a washer (14) are installed at the end of the hip joint shaft (13).

5. The bionic biped robot with variable stiffness joints and double joint flexibility according to claim 3, characterized in that: A hip joint motor inner shell plate (23) is connected between the two hip joint motor shells (10), and a groove for placing the hip joint motor (21) is provided on the hip joint motor inner shell plate (23).

6. The bionic biped robot with variable stiffness joints and double joint flexibility according to claim 5, characterized in that: The synchronous belt pinion housing (22) and the hip joint motor housing (10) are both connected to the outer housing plate (17) of the hip joint motor.

7. The bionic biped robot with variable stiffness joints and double joint flexibility according to claim 6, characterized in that: The trunk linear motor, the hip joint motor (21), the thigh linear motor, the ankle joint motor (34), the knee joint rear linear motor (36), and the knee joint front linear motor (48) are controlled by STM32 control boards respectively, and the multiple STM32 control boards communicate with the industrial computer.

8. The bionic biped robot with variable stiffness joints and double joint flexibility according to claim 7, characterized in that: An electronic component placement plate (21) is arranged on the upper part of the hip joint motor housing (10) for placing an industrial computer, an STM32 control board, and a battery, and the battery supplies power to the industrial computer and the STM32 control board.

9. The bionic biped robot with variable stiffness joints and double joint flexibility according to claim 1, characterized in that: The trunk linear motor is installed in a trunk linear motor installation box (8), and the top of the trunk linear motor installation box (8) is connected to the trunk shell (11).

10. The bionic biped robot with variable stiffness joints and double joint flexibility according to claim 1, characterized in that: The boss on the inner side of the knee joint output end baffle (46) is provided with two annular grooves.

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