A multi-link differential drive mechanism for mimicking lower leg and foot motion

Abstract

The application belongs to the technical field of bionic robots, and particularly relates to a multi-link differential drive mechanism for the action of a lower leg and a foot sole. The technical scheme is as follows: a multi-link differential drive mechanism for the action of a lower leg and a foot sole, comprising a thigh base, the thigh base being connected with a lower leg base through a rotating shaft, the lower leg base being rotatably connected with a cross beam, and the two ends of the cross beam being connected with a driving mechanism and a steel wire rope, the other end of the steel wire rope being connected with an ankle joint lever, the lower end of the lower leg base being rotatably connected with a foot sole assembly, the foot sole assembly being rotatably connected with a sliding sleeve through a spline, and the other end of the ankle joint lever being rotatably connected with the side of the sliding sleeve. The application provides a multi-link differential mechanism for driving the bending of the lower leg base and the torsion of the foot sole by the driving mechanism.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of bionic robots, and particularly relates to a multi-link differential drive mechanism for the movement of a lower leg and a foot sole. BACKGROUND

[0002] The field of robot research is developing towards aerospace, water surface and underwater, underground pipeline and other environments to replace humans to enter unpredictable environments for rescue, reconnaissance, detection and other operation tasks. Therefore, the requirements for the movement flexibility and environmental adaptability of robots are further improved. Bionic robots can adapt to different environments and have a wide range of activities and strong mobility due to the simulation of certain characteristics of animals, and have a wide application prospect in the fields of climbing rescue, spacecraft extravehicular walking and the like.

[0003] A patent with the application number CN202210265223.5 discloses a mechanical leg and a bionic robot, and belongs to the technical field of robots. The mechanical leg comprises a femur joint, a thigh, a knee joint, a lower leg, an ankle joint and a foot connected to the ankle joint through a universal ball head connecting rod. The foot has a bionic foot sole, the bionic foot sole is made of an adsorbing material, the bionic foot sole is used for forming physical adsorption with a road surface, at least one spring is arranged between the bionic foot sole and the ball seat of the universal ball head connecting rod, and each spring is used for isolating the excitation of the road surface from the robot body. The femur joint, the knee joint and the ankle joint each have one degree of rotational freedom. The bionic robot has the beneficial effects of shock absorption, improved adsorption and climbing ability on different roughness or different material planes through the bionic foot sole, reduced space required for the movement of the mechanical leg structure, and a more compact structure.

[0004] However, the bending of the lower leg and the twisting of the foot of the above-mentioned device are controlled by different driving devices respectively, and the structure is relatively complex. SUMMARY

[0005] In order to solve the above-mentioned problems existing in the prior art, the purpose of the present application is to provide a multi-link differential mechanism for driving the bending of a lower leg base body and the twisting of a foot sole by driving mechanisms respectively.

[0006] The technical scheme adopted by the present application is as follows:

[0007] A multi-link differential drive mechanism for the movement of a lower leg and a foot sole, comprising a thigh base body, the thigh base body being connected with a lower leg base body through a rotating shaft, the lower leg base body being rotatably connected with a cross beam, and the two ends of the cross beam being connected with driving mechanisms between the cross beam and the thigh base body; one end of the driving mechanism connected with the cross beam is connected with a steel wire rope, the lower leg base body is rotatably connected with an ankle joint lever, one end of the ankle joint lever is connected with the other end of the steel wire rope, the lower end of the lower leg base body is rotatably connected with a foot sole assembly, the foot sole assembly is connected with a sliding sleeve through a spline, and the other end of the ankle joint lever is rotatably connected with the side edge of the sliding sleeve.

[0008] When the two driving mechanisms of the present application drive the two ends of the cross beam rod to move in the same direction, the force is concentrated at the connecting point of the cross beam rod and the lower leg base, which pushes the lower leg base to rotate around the rotating shaft, thereby realizing the bending of the lower leg. When the two driving mechanisms drive the two ends of the cross beam rod to move in opposite directions, the end of the cross beam rod that is lifted pulls the steel wire rope, which in turn pulls the ankle joint lever on the side, the ankle joint lever pushes the sliding sleeve and the sole assembly to rotate by a certain angle, thereby realizing the torsion of the sole assembly. The bending of the lower leg base and the torsion of the sole assembly are both driven by driving mechanisms, which can simplify the structure, save space, and ensure the bionics of the shape under the action of the lower leg and the sole.

[0009] As a preferred scheme of the present application, the driving mechanism comprises a rotary power device, the rotary power device is installed on the thigh base, the outer circle of the output end of the rotary power device is rotationally connected with a driving link, the two sides of the rotating shaft are both rotationally connected with a triangular lever, the other end of the driving link is rotationally connected with one end of the triangular lever, the other end of the triangular lever is rotationally connected with a lower leg link, and the other end of the lower leg link is rotationally connected with the end of the cross beam rod.

[0010] The output end of the rotary power device drives the driving link to move, the driving link drives the triangular lever to rotate, the other end of the triangular lever drives the lower leg link to move, and then the lower leg link can drive one end of the cross beam rod to move. When the two driving links move in the same direction, the two lower leg links move in the same direction through the conversion of the two triangular levers, at this time the two lower leg links are relatively stationary, the force is concentrated at the fulcrum of the cross beam rod to push the lower leg base to rotate around the rotating shaft. When the two driving links move in opposite directions, the driving link on one side moves upward, and the lower leg link moves upward correspondingly through the conversion of the triangular lever plate, and the lower leg link on the other side moves downward correspondingly. At this time, the force is no longer concentrated at the fulcrum of the cross beam rod, but is continuously transmitted along the side of the cross beam rod that is lifted, and the upward tension of the steel wire rope pulls the ankle joint lever, changes the direction of the force through the ankle joint lever, and drives the sliding sleeve to rotate, thereby driving the sole assembly to twist.

[0011] As a preferred scheme of the present application, a limiting step is arranged on the thigh base to limit one side of the triangular lever, and when one end of the triangular lever contacts the limiting step, the thigh base is collinear with the lower leg base. The limiting step can limit one side of the triangular lever, so that the limit position of the rotation of the lower leg base is collinear with the thigh base, simulating the working state of the real human lower leg.

[0012] As a preferred scheme of the present application, the two rotary power devices are arranged on the thigh base in an up-down manner. The two rotary power devices are arranged in an up-down manner, which reasonably utilizes the space of the thigh base, and makes the shape of the thigh more natural.

[0013] As a preferred embodiment of the present invention, the rotary power device includes a central shaft, a motor stator connected to the central shaft, a motor rotor sleeved on the motor stator, a harmonic reduction unit connected to the motor rotor, the output end of the harmonic reduction unit being rotatably connected to the central shaft, a drive connecting rod being rotatably connected to the outer ring of the output end of the harmonic reduction unit, a harmonic rigid wheel meshing with the output end of the harmonic reduction unit, the harmonic rigid wheel being fixed to the thigh base, and a rear cover being fixed to one end of the central shaft, the rear cover being fixed to the harmonic rigid wheel.

[0014] The output speed of the harmonic reducer is significantly lower than that of the cam, resulting in a stable and low-speed output from the harmonic rotary power unit. The harmonic reducer meshes with the harmonic rigid wheel, thus providing high transmission accuracy relative to the cam at the output of the harmonic rotary power unit. The output of the harmonic reducer is rotatably connected to the central shaft, ensuring stable support for its output.

[0015] As a preferred embodiment of the present invention, the harmonic reduction unit includes a cam, which is fixed on the motor rotor. A flexible bearing is mounted on the cam, and a flexible wheel is sleeved on the outer ring of the flexible bearing. The flexible wheel meshes with the harmonic rigid wheel. The number of teeth on the flexible wheel is less than the number of teeth on the harmonic rigid wheel. An output flange is fixed on the flexible wheel. The flexible wheel is rotatably connected to the central shaft, and the drive connecting rod is rotatably connected to the outer ring of the output flange.

[0016] When the motor is powered on, the motor rotor rotates relative to the motor stator. The motor rotor drives the cam to rotate, and the cam drives the flex wheel to mesh with the harmonic rigid wheel through a flexible bearing. If the number of teeth on the flex wheel is N less than the number of teeth on the harmonic rigid wheel, then when the cam rotates one revolution, the flex wheel rotates N teeth relative to the harmonic rigid wheel. This results in a greater speed reduction for the output flange connected to the flex wheel, ensuring a stable output force, and ensuring transmission accuracy through gear transmission.

[0017] In a preferred embodiment of the present invention, the foot assembly includes a foot pivot, which is rotatably connected to the lower leg base. A sliding sleeve is connected to the foot pivot via a spline. A cross-shaped ankle joint is rotatably connected to the foot, and the cross-shaped ankle joint is connected to the foot body. The cross-shaped ankle joint connects the foot body to the foot pivot, allowing the foot body to move forward and backward, rotate left and right, or perform a combination of both movements, thereby improving the flexibility of the foot body.

[0018] In a preferred embodiment of the present invention, the cross-shaped ankle joint includes an upper bearing seat, a cross-shaped pivot, and a lower bearing seat. The cross-shaped pivot includes two mutually perpendicular pivots. The upper bearing seat is rotatably connected to one of the pivots, and the lower bearing seat is rotatably connected to the other pivot. The upper bearing seat is fixed to the foot pivot, and the lower bearing seat is fixed to the foot body. When the upper bearing seat rotates relative to the lower bearing seat around one of the pivots, the foot swings back and forth. When the upper bearing seat rotates relative to the lower bearing seat around the other pivot, the foot rotates left and right.

[0019] In a preferred embodiment of the present invention, a plurality of guides are installed on the lower leg base, and the guides are provided with rope grooves, in which steel wire ropes are sleeved. The guides can guide the steel wire ropes, ensuring that the steel wire ropes can accurately transmit force to the ankle joint lever.

[0020] In a preferred embodiment of the present invention, the ankle joint lever and the side of the sliding sleeve are connected by a fisheye bearing. Since the ankle joint lever rotates in a plane, the angle between the ankle joint lever and the sliding sleeve will change during the process of the ankle joint lever pushing the sliding sleeve to rotate. The fisheye bearing can adapt to the changes in the relative position and angle between the ankle joint lever and the sliding sleeve.

[0021] The beneficial effects of this invention are as follows:

[0022] When the two drive mechanisms of this invention drive the two ends of the crossbeam to move in the same direction, the force is concentrated at the connection point between the crossbeam and the lower leg base, pushing the lower leg base to rotate around the rotation axis, thereby achieving bending of the lower leg. When the two drive mechanisms drive the two ends of the crossbeam to move in opposite directions, the raised end of the crossbeam pulls the steel cable, which in turn pulls the ankle joint lever. The ankle joint lever pushes the sliding sleeve and the foot assembly to rotate at a certain angle, achieving torsion of the foot assembly. In this invention, both the bending of the lower leg base and the torsion of the foot assembly are driven by drive mechanisms, which simplifies the structure, saves space, and ensures biomimetic shape while achieving lower leg and foot movements. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the structure in the first direction of the present invention;

[0024] Figure 2 This is a schematic diagram of the structure in the second direction of the present invention;

[0025] Figure 3 yes Figure 1 A magnified view of a section at point A in the middle;

[0026] Figure 4 yes Figure 1 A magnified view of a section at point B in the middle;

[0027] Figure 5 This is a schematic diagram of the cross-shaped rotating shaft;

[0028] Figure 6 This is a cross-sectional view of a rotary power unit;

[0029] Figure 7 This is a partial structural diagram of the rotating power unit.

[0030] In the figure: 1-thigh base body; 2-rotation shaft; 3-calf base body; 4-crossbeam rod; 5-driving mechanism; 6-steel wire rope; 7-ankle joint lever; 8-sole assembly; 9-sliding sleeve; 11-limiting step; 31-guide; 51-rotary power device; 52-driving connecting rod; 53-triangle lever; 54-calf connecting rod; 81-sole rotation shaft; 82-cross ankle joint; 83-sole main body; 311-rope groove; 821-upper bearing seat; 822-cross rotation shaft; 823-lower bearing seat; a1-center shaft; a2-motor stator; a3-motor rotor; a4-harmonic reduction unit; a5-harmonic gear; a6-crossed roller bearing; a7-rear cover; a11-rolling bearing; a41-cam; a42-flexible bearing; a43-flexspline; a44-output flange. DETAILED DESCRIPTION

[0031] In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the following will be combined with the accompanying drawings for the embodiments of the present application to make a clear and complete description of the technical solutions in the embodiments of the present application. Obviously, the described embodiments are a part of the embodiments of the present application, rather than all the embodiments. The components of the embodiments of the present application described and shown in the accompanying drawings can be arranged and designed in various different configurations.

[0032] Therefore, the following detailed description of the embodiments of the present application provided in the accompanying drawings is not intended to limit the scope of the claimed present application, but only represents selected embodiments of the present application. All other embodiments obtained by a person of ordinary skill in the art without creative labor based on the embodiments in the present application belong to the scope of protection of the present application. It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict.

[0033] As shown in Figure 1 and Figure 2 The multi-link differential driving calf and sole action mechanism of the embodiment comprises a thigh base body 1, the thigh base body 1 is connected with a calf base body 3 through a rotation shaft 2, the calf base body 3 is rotationally connected with a crossbeam rod 4, and the two ends of the crossbeam rod 4 are both connected with a driving mechanism 5 between the thigh base body 1; one end of the driving mechanism 5 connected with the crossbeam rod 4 is connected with a steel wire rope 6, the calf base body 3 is rotationally connected with an ankle joint lever 7, one end of the ankle joint lever 7 is connected with the other end of the steel wire rope 6, the lower end of the calf base body 3 is rotationally connected with a sole assembly 8, the sole assembly 8 is connected with a sliding sleeve 9 through a spline, and the other end of the ankle joint lever 7 is rotationally connected with the side edge of the sliding sleeve 9.

[0034] When the two ends of the cross beam rod 4 are driven by the two driving mechanisms 5 to move in the same direction, the force is concentrated at the connecting point of the cross beam rod 4 and the lower leg base 3, and the lower leg base 3 is pushed to rotate around the rotating shaft 2, so as to realize the bending of the lower leg. When the two ends of the cross beam rod 4 are driven by the two driving mechanisms 5 to move in opposite directions, the end of the cross beam rod 4 that is lifted pulls the steel wire rope 6, and the steel wire rope 6 on the side pulls the ankle joint lever 7, and the ankle joint lever 7 pushes the sliding sleeve 9 and the instep assembly 8 to rotate by a certain angle, so as to realize the torsion of the instep assembly 8. The bending of the lower leg base 3 and the torsion of the instep assembly 8 are both driven by the driving mechanism 5, which can simplify the structure, save space, and ensure the bionics of the shape under the action of the lower leg and the instep.

[0035] When one end of the cross beam rod 4 is lifted and the other end is lowered, the steel wire rope 6 at the lowered end of the cross beam rod 4 is relaxed, so that the steel wire rope 6 on the side has no force on the ankle joint lever 7. At this time, the force at the connecting point of the cross beam rod 4 and the lower leg base 3 is counteracted, so the lower leg base 3 will not bend. When the steel wire rope 6 on one side pulls the ankle joint lever 7, the instep assembly 8 is twisted clockwise; when the steel wire rope 6 on the other side pulls the ankle joint lever 7, the instep assembly 8 is twisted counterclockwise.

[0036] The ankle joint lever 7 is in a right angle shape, and when the steel wire rope 6 pulls the ankle joint lever 7 to rotate, the ankle joint lever 7 drives the sliding action. Since the height of the lower end of the ankle joint lever 7 will change, the sliding sleeve 9 will generate a certain distance relative to the instep assembly 8, avoiding motion interference. The ankle joint lever 7 and the side of the sliding sleeve 9 are connected through a fish eye bearing. Since the ankle joint lever 7 rotates in a plane, the angle between the ankle joint lever 7 and the sliding sleeve 9 will change during the process of the ankle joint lever 7 pushing the sliding sleeve 9 to rotate, and the fish eye bearing can adapt to the change of the relative position and angle between the ankle joint lever 7 and the sliding sleeve 9.

[0037] Further, the thigh base 1 is provided with a limiting step 11 limiting one side of the triangular lever 53, and when one end of the triangular lever 53 contacts the limiting step 11, the thigh base 1 is collinear with the lower leg base 3. The limiting step 11 can limit one side of the triangular lever 53, so that the limit position of the rotation of the lower leg base 3 is collinear with the thigh base 1, simulating the working state of the real human lower leg. Since the driving of the lower leg assembly torsion requires the two driving mechanisms 5 to drive the two ends of the cross beam rod 4 to move in opposite directions, both triangular levers 53 need to be able to rotate to achieve this. Due to the limiting effect of the limiting step 11, the lower leg base 3 must be in a bent state to simultaneously drive the two triangular levers 53 to rotate in opposite directions.

[0038] The two rotating power devices 51 are arranged on the thigh base 1 in an up-down manner. The two rotating power devices 51 are arranged in an up-down manner, which reasonably utilizes the space of the thigh base 1, so that the shape of the thigh is more natural.

[0039] In order to guide the steel wire rope 6, a plurality of guides 31 are installed on the shank base 3, the guides 31 are provided with rope grooves 311, and the steel wire rope 6 is sleeved in the rope grooves 311. The guides 31 can guide the steel wire rope 6, so that the steel wire rope 6 can accurately transmit the force to the ankle lever 7.

[0040] Specifically, as shown in the figure, Figure 3 The driving mechanism 5 includes a rotary power device 51, the rotary power device 51 is installed on the thigh base 1, the outer circle of the output end of the rotary power device 51 is rotationally connected with a driving link 52, both sides of the rotating shaft 2 are rotationally connected with a triangular lever 53, the other end of the driving link 52 is rotationally connected with one end of the triangular lever 53, the other end of the triangular lever 53 is rotationally connected with a shank link 54, the other end of the shank link 54 is rotationally connected with the end of the cross beam 4, and the steel wire rope 6 is connected to one end of the shank link 54 connected with the cross beam 4.

[0041] The output end of the rotary power device 51 drives the driving link 52 to act, the driving link 52 drives the triangular lever 53 to rotate, the other end of the triangular lever 53 drives the shank link 54 to act, and then the shank link 54 can drive one end of the cross beam 4 to act. When the two driving links 52 act in the same direction, the conversion of the two triangular levers 53 makes the two shank links 54 act in the same direction, at this time, the two shank links 54 are relatively stationary, and the force is concentrated to the fulcrum of the cross beam 4 to push the shank base 3 to rotate around the rotating shaft 2. When the two driving links 52 move in opposite directions, when one side of the driving link 52 moves upward, the conversion of the triangular lever 53 plate makes the shank link 54 correspondingly move upward, and the other side of the shank link 54 correspondingly moves downward. At this time, the force is no longer concentrated to the fulcrum of the cross beam 4, but is continuously transmitted along the side of the cross beam 4 that is lifted up, and the upward tension of the steel wire rope 6 pulls the ankle lever 7, changes the direction of the force through the ankle lever 7, and then drives the sliding sleeve 9 to rotate, so as to drive the sole assembly 8 to twist.

[0042] As shown in the figure, Figure 6 The rotary power device 51 includes a center shaft a1, a motor stator a2 is connected to the center shaft a1, a motor rotor a3 is sleeved on the motor stator a2, a harmonic reducer unit a4 is connected to the motor rotor a3, the output end of the harmonic reducer unit a4 is rotationally connected with the center shaft a1, the driving link 52 is rotationally connected with the outer circle of the output end of the harmonic reducer unit a4, the output end of the harmonic reducer unit a4 is toothedly engaged with a harmonic gear a5, the harmonic gear a5 is fixed with the thigh base 1, a rear cover a7 is fixed to one end of the center shaft a1, and the rear cover a7 is fixed with the harmonic gear a5.

[0043] The rotation speed of the output end of the harmonic reduction unit a4 is greatly reduced relative to the rotation speed of the cam a41, so that the output end of the harmonic rotary power device 51 is stable and low-speed output. The harmonic reduction unit a4 is in gear engagement with the harmonic gear a5, so that the output end of the harmonic rotary power device 51 has high transmission accuracy relative to the cam a41. The output end of the harmonic reduction unit a4 is rotationally connected to the central shaft a1, so that the output end of the harmonic reduction unit a4 can be stably supported.

[0044] As shown in Figure 7 The harmonic reduction unit a4 includes the cam a41 fixed to the motor rotor a3, the flexible bearing a42 mounted on the cam a41, the flexspline a43 sleeved with the outer ring of the flexible bearing a42, the flexspline a43 in gear engagement with the harmonic gear a5, the flexspline a43 having a smaller number of teeth than the harmonic gear a5, the output flange a44 fixed to the flexspline a43, the flexspline a43 fixed to the central shaft a1, and the driving connecting rod 52 rotationally connected to the outer ring of the output flange a44. The cam a41 and the flexible bearing a42 are both elliptical in shape, and the flexspline a43 is in engagement with the harmonic gear a5 at two positions. The flexible bearing a42 pushes the flexspline a43 to engage with the harmonic gear a5 for transmission at two positions, so as to ensure stable transmission of the flexspline a43 and the harmonic gear a5.

[0045] The motor stator a2 and the electronic rotor a3 are built in the flexspline a43, so as to effectively utilize the space, reduce the volume of the rotary power device 51, and simplify the structure.

[0046] When the motor is powered on, the motor rotor a3 rotates relative to the motor stator a2, the motor rotor a3 drives the cam a41 to rotate, and the cam a41 pushes the flexspline a43 to engage with the harmonic gear a5 for transmission through the flexible bearing a42. If the flexspline a43 has N fewer teeth than the harmonic gear a5, when the cam a41 rotates one circle, the flexspline a43 rotates N teeth relative to the harmonic gear a5, so that the output flange a44 connected to the flexspline a43 is greatly reduced in speed, and the stable output force is ensured, and the transmission accuracy is ensured through the gear transmission.

[0047] In order to support the cam a41, the inner side of the cam a41 is connected with the central shaft a1 through the rolling bearing a11. The central shaft a1 reliably supports the cam a41, and the central shaft a1 and the cam a41 can relatively rotate.

[0048] In order to support the harmonic gear a5, the rotary power device further includes the cross roller bearing a6, the inner ring of the cross roller bearing a6 is integrally formed or fixedly connected with the output flange a44, and the outer ring of the cross roller bearing a6 is integrally formed or fixedly connected with the harmonic gear a5. The outer ring of the cross roller bearing a6 stably supports the harmonic gear a5.

[0049] AsFigure 4 As shown in the figure, the instep assembly 8 comprises an instep rotating shaft 81, which is rotatably connected with the lower leg base 3, and the sliding sleeve 9 is connected with the instep rotating shaft 81 through a spline connection. The instep rotating shaft 81 is rotatably connected with a cross ankle joint 82, and the cross ankle joint 82 is connected with an instep body 83. The cross ankle joint is connected between the instep body 83 and the instep rotating shaft 81, and the instep body 83 can swing forward and backward, turn left and right, or compound motion of the two, so as to improve the flexibility of the instep body 83.

[0050] As shown in the figure, Figure 5 As shown in the figure, the cross ankle joint 82 comprises an upper bearing seat 821, a cross rotating shaft 822 and a lower bearing seat 823. The cross rotating shaft 822 comprises two perpendicular rotating shafts. The upper bearing seat 821 is rotatably connected with one of the rotating shafts of the cross rotating shaft 822, and the lower bearing seat 823 is rotatably connected with the other rotating shaft of the cross rotating shaft 822. The upper bearing seat 821 is fixed with the instep rotating shaft 81, and the lower bearing seat 823 is fixed with the instep body 83. When the upper bearing seat 821 rotates relative to the lower bearing seat 823 around one of the rotating shafts, the instep swings forward and backward. When the upper bearing seat 821 rotates relative to the lower bearing seat 823 around the other rotating shaft, the instep turns left and right.

[0051] The present application is not limited to the above-mentioned optional embodiments, and anyone can derive other various forms of products under the inspiration of the present application, but regardless of any changes in shape or structure, any technical solutions falling within the scope defined by the claims of the present application fall within the protection scope of the present application.

Claims

1. A mechanism for multi-link differential drive of lower leg and foot movement, characterized in that: The system includes a thigh base (1), a calf base (3) connected to the thigh base (1) via a rotating shaft (2), a crossbeam (4) rotatably connected to the calf base (3), and a drive mechanism (5) connected to both ends of the crossbeam (4) and the thigh base (1); a wire rope (6) is connected to one end of the drive mechanism (5) connected to the crossbeam (4), an ankle joint lever (7) rotatably connected to the calf base (3), one end of the ankle joint lever (7) being connected to the other end of the wire rope (6), a foot assembly (8) rotatably connected to the lower end of the calf base (3), a sliding sleeve (9) connected to the foot assembly (8) via a spline, and the other end of the ankle joint lever (7) rotatably connected to the side of the sliding sleeve (9); The drive mechanism (5) includes a rotary power device (51), which is mounted on the thigh base (1). The outer ring of the output end of the rotary power device (51) is rotatably connected to a drive link (52). Both sides of the rotating shaft (2) are rotatably connected to triangular levers (53). The other end of the drive link (52) is rotatably connected to one end of the triangular lever (53). The other end of the triangular lever (53) is rotatably connected to a calf link (54). The other end of the calf link (54) is rotatably connected to the end of the crossbeam (4). A steel wire rope (6) is connected to one end of the calf link (54) and the connecting crossbeam (4).

2. The mechanism for multi-link differential drive of lower leg and foot movement according to claim 1, characterized in that: The thigh base (1) is provided with a limiting step (11) that limits one side of the triangular lever (53). When one end of the triangular lever (53) contacts the limiting step (11), the thigh base (1) and the calf base (3) are collinear.

3. The mechanism for multi-link differential drive of lower leg and foot movement according to claim 1, characterized in that: Two rotating power devices (51) are arranged vertically on the thigh base (1).

4. The mechanism for multi-link differential drive of lower leg and foot movement according to claim 1, characterized in that: The rotating power device (51) includes a central shaft (a1), a motor stator (a2) connected to the central shaft (a1), a motor rotor (a3) ​​sleeved on the motor stator (a2), a harmonic reduction unit (a4) connected to the motor rotor (a3), a drive link (52) rotatably connected to the outer ring of the output end of the harmonic reduction unit (a4), a harmonic rigid wheel (a5) meshing with the output end of the harmonic reduction unit (a4), the harmonic rigid wheel (a5) being fixed to the thigh base (1), a rear cover (a7) being fixed to one end of the central shaft (a1), and the rear cover (a7) being fixed to the harmonic rigid wheel (a5).

5. The mechanism for multi-link differential drive of lower leg and foot movement according to claim 4, characterized in that: The harmonic deceleration unit (a4) includes a cam (a41), which is fixed on the motor rotor (a3). A flexible bearing (a42) is mounted on the cam (a41). A flexible wheel (a43) is sleeved on the outer ring of the flexible bearing (a42). The flexible wheel (a43) meshes with the harmonic rigid wheel (a5). The number of teeth on the flexible wheel (a43) is less than the number of teeth on the harmonic rigid wheel (a5). An output flange (a44) is fixed on the flexible wheel (a43). The drive connecting rod (52) is rotatably connected to the outer ring of the output flange (a44).

6. The mechanism for multi-link differential drive of lower leg and foot movement according to claim 1, characterized in that: The foot assembly (8) includes a foot pivot (81), which is rotatably connected to the lower leg base (3). The sliding sleeve (9) is connected to the foot pivot (81) via a spline. The foot is rotatably connected to a cross ankle joint (82), which is connected to the foot body (83).

7. The mechanism for multi-link differential drive of lower leg and foot movement according to claim 6, characterized in that: The cross-shaped ankle joint (82) includes an upper bearing seat (821), a cross-shaped pivot (822), and a lower bearing seat (823). The cross-shaped pivot (822) includes two mutually perpendicular pivots. The upper bearing seat (821) is rotatably connected to one of the pivots of the cross-shaped pivot (822), and the lower bearing seat (823) is rotatably connected to the other pivot of the cross-shaped pivot (822). The upper bearing seat (821) is fixed to the foot pivot (81), and the lower bearing seat (823) is fixed to the foot body (83).

8. The mechanism for multi-link differential drive of lower leg and foot movement according to claim 1, characterized in that: Several guides (31) are installed on the lower leg base (3), and rope grooves (311) are provided on the guides (31), with steel wire ropes (6) sleeved in the rope grooves (311).

9. A mechanism for multi-link differential drive of lower leg and foot movement according to any one of claims 1 to 8, characterized in that: The ankle joint lever (7) is connected to the side of the sleeve (9) via a fisheye bearing.

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