Bionic foot sole and lower leg structure

Abstract

The present application belongs to the technical field of bionic robot, and particularly relates to a bionic foot sole and lower leg structure. The technical scheme is as follows: a bionic foot sole and lower leg structure, comprising a lower leg bone and a foot sole, the lower end of the lower leg bone is rotationally connected with an integrated joint, the output end of the integrated joint is fixedly connected with the foot sole, a linear driver is installed on the lower leg bone, the output shaft of the linear driver is rotationally connected with a driving link, a heel support seat is fixedly arranged on the shell of the integrated joint, and the end of the driving link away from the output shaft of the linear driver is rotationally connected with the heel support seat. The bionic foot sole and lower leg structure is provided in a compact, low-inertia and driving decoupling manner, and simultaneously realizes the actions of metatarsophalangeal flexion, dorsiflexion, inversion and eversion.

Description

Technical Field

[0001] This invention belongs to the field of bionic robot technology, and specifically relates to a bionic foot and lower leg structure. Background Technology

[0002] Bionic robots aim to mimic the movement patterns, behaviors, and interaction capabilities of living organisms to achieve efficient, stable, and human-like movement in complex terrains. Among these, the lower limb structure, especially the connection and drive mechanism between the foot and lower leg, directly determines the gait naturalness, terrain adaptability, and energy efficiency of the robot's walking.

[0003] In existing technologies, the lower limb structures of bionic robots are mainly divided into two categories: rigid and flexible (or containing passive elastic elements). Common rigid foot structures (such as flat or simple curved soles) achieve support through point or line contact with the ground, but they lack the multi-degree-of-freedom joint coordination unique to human feet. This results in a stiff gait when the robot walks, making it unable to achieve active plantar flexion and dorsiflexion of the foot. Therefore, the kinetic chain is discontinuous and energy loss is relatively large when pushing off the ground to jump, cushioning the landing, and walking uphill.

[0004] To address these issues, some research and patents have disclosed bionic feet with single- or multi-degree-of-freedom articulated structures. For example, some designs incorporate a motor-driven rotation axis at the ankle joint, enabling relative rotation between the lower leg and foot to simulate plantar flexion and dorsiflexion. However, such structures typically simplify the ankle joint to a single-direction rotational joint, neglecting the foot's degrees of freedom in the medial and lateral directions. During human walking, the foot also needs to achieve inversion and eversion via structures such as the subtalar joint to adapt to inclined or uneven surfaces (such as shoulders, gravel, and slopes) and maintain balance. Most existing robotic lower limb structures fail to simultaneously provide inversion / everversion degrees of freedom, or although a second rotation axis is added, it lacks proper kinematic decoupling and drive coordination with the plantar flexion / dorsiflexion axis, resulting in a still mechanical gait and susceptibility to lateral instability on uneven surfaces.

[0005] Furthermore, existing solutions for implementing multi-degree-of-freedom ankle-foot mechanisms often employ complex serial or parallel drive layouts, resulting in bulky structures, large inertia, and highly coupled control algorithms. This makes it difficult to balance real-time response and energy efficiency while ensuring the naturalness of the bionic gait. In particular, these solutions typically directly borrow joint designs from industrial robotic arms or medical devices (such as prostheses and orthotics). However, medical devices are designed for human weight and physiological actuation conditions, and their load, speed, and control logic differ fundamentally from those of autonomous walking bionic robots, making direct application unsuitable. Summary of the Invention

[0006] In order to solve the above-mentioned problems in the prior art, the purpose of this invention is to provide a bionic foot and lower leg structure that can simultaneously realize plantar flexion, dorsiflexion, inversion and eversion movements in a compact, low-inertia and drive-decoupled manner.

[0007] The technical solution adopted in this invention is as follows: A bionic foot and lower leg structure includes a shinbone and a foot. The lower end of the shinbone is rotatably connected to an integrated joint. The output end of the integrated joint is fixedly connected to the foot. A linear actuator is installed on the shinbone. The output shaft of the linear actuator is rotatably connected to a drive linkage. An ankle support is fixed on the housing of the integrated joint. The end of the drive linkage away from the output shaft of the linear actuator is rotatably connected to the ankle support.

[0008] The linear actuator functions as the skeletal structure of the lower leg. It drives the output shaft, and a drive linkage is rotatably connected to the output shaft, adapting to angle changes during its extension and retraction. The drive linkage is also rotatably connected to the ankle support, adapting to its angle changes. The ankle support is connected to an integrated joint, the output end of which is fixedly connected to the foot, while the ankle support is rotatably connected to the foot. The extension and retraction of the linear actuator's output shaft drives the drive linkage to plantarflex or dorsiflex the foot, while the rotation of the integrated joint's output end causes inversion or eversion of the foot. When the linear actuator and integrated joint move simultaneously, the foot performs a compound movement of plantarflexion / dorsiflexion and inversion / everversion.

[0009] This invention utilizes a linear actuator within the shinbone as the power source for plantar flexion or dorsiflexion of the foot. The output shaft of the linear actuator drives a connecting rod, which in turn pulls the foot in plantar flexion or dorsiflexion. By placing the linear actuator, its output shaft, and the connecting rod within the shinbone, the internal space of the shin can be fully utilized, ensuring that the shape of the shinbone and foot closely resembles that of a real human shin and foot. Furthermore, the linear actuator, its output shaft, and the connecting rod, acting as the skeletal framework of the shin, enhance the supporting force of the shin.

[0010] As a preferred embodiment of the present invention, a vertically arranged sliding groove is provided inside the shinbone, and a roller follower is installed on the needle roller bearing between the output shaft of the linear actuator and the drive connecting rod, and the roller follower is sleeved in the sliding groove.

[0011] When the linear actuator is activated, its output shaft rises or falls. At this time, the roller follower always rolls within the sliding space of the tibia, thus ensuring that the roller follower is accurately limited. Consequently, the output shaft and drive linkage of the linear actuator can move more smoothly.

[0012] In a preferred embodiment of the present invention, grooves are provided on both sides of the interior of the tibia, and roller followers are installed at both ends of the needle roller bearing between the output shaft of the linear actuator and the drive connecting rod. The two roller followers are respectively fitted into the grooves at corresponding positions. The roller followers on both sides can further improve the stability of the needle roller bearing at this location, ensuring smooth operation of the output shaft of the linear actuator and the drive connecting rod.

[0013] In a preferred embodiment of the present invention, the heel portion of the foot is rotatably connected to the ankle support via a needle roller bearing. The ankle support not only connects to the drive linkage but also rotatably connects to the heel portion of the foot, thus providing reliable support for the heel. The forefoot is fixed to the output end of the integrated joint, and the rear end of the foot is rotatably connected to the ankle support, ensuring reliable support for both the forefoot and rear ends and improving foot stability.

[0014] As a preferred embodiment of the present invention, the pin bearing between the heel portion of the foot and the ankle support is coaxial with the integrated joint.

[0015] Because the forefoot is fixed to the output end of the integrated joint, the rotation axis of the forefoot is coaxial with the axis of the integrated joint. Consequently, both the forefoot and the heel are coaxial with the integrated joint, ensuring reliable rotation of the foot during inversion or eversion and avoiding movement interference.

[0016] In a preferred embodiment of the present invention, the shinbone includes a shin body and a support component detachably connected to the lower end of the shin body. The support component is rotatably connected to the housing of the integrated joint via a needle roller bearing. The support component is connected to the shin body by several bolts for easy disassembly, thereby allowing the foot to be separated from the shinbone for convenient assembly and disassembly.

[0017] In a preferred embodiment of the present invention, an opening groove is provided on the lower part of the posterior side of the tibia, and the drive link extends out from the opening groove; the axis of the integrated joint is coplanar with the center line of the drive link. The lower end of the drive link extends out from the opening groove of the tibia to avoid motion interference between the drive link and the tibia when the drive link moves.

[0018] As a preferred embodiment of the present invention, the axis of the integrated joint is arranged parallel to the extension direction of the foot, and the output end of the integrated joint rotates to drive the foot to turn inward or outward.

[0019] As a preferred embodiment of the present invention, the integrated joint is a harmonic geared motor; the harmonic geared motor includes a central shaft, a motor stator mounted on the central shaft, a motor rotor sleeved on the motor stator, a cam fixed on the motor rotor, a flexible wheel connected to the cam via a flexible bearing, the flexible wheel meshing with a harmonic rigid wheel, the number of teeth of the flexible wheel being less than the number of teeth of the harmonic rigid wheel, an output flange fixed on the flexible wheel, the output flange being fixed to the flexible wheel, a rear cover fixed to one end of the central shaft, the rear cover being fixed to the harmonic rigid wheel; the harmonic rigid wheel is rotatably connected to the shinbone, and the output flange is fixedly connected to the foot.

[0020] 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.

[0021] As a preferred embodiment of the present invention, a rolling bearing is provided between the central shaft and the cam; the harmonic reduction motor further includes a crossed roller bearing, the inner ring of which is integrally formed or fixedly connected to the output flange, and the outer ring of which is integrally formed or fixedly connected to the harmonic rigid wheel.

[0022] The beneficial effects of this invention are as follows: 1. The linear actuator of the present invention drives the output shaft of the linear actuator, and the drive linkage is rotatably connected to the output shaft of the linear actuator to adapt to the angle change when the output shaft of the linear actuator extends or retracts. The drive linkage is rotatably connected to the ankle support seat to adapt to the angle change of the drive linkage. The ankle support seat is connected to the integrated joint, the output end of the integrated joint is fixedly connected to the foot, and the ankle support seat is rotatably connected to the foot. When the output shaft of the linear actuator extends or retracts, it drives the drive linkage to push the foot to plantarflex or dorsiflex, and the output end of the integrated joint rotates to drive the foot to invert or evert. When the linear actuator and the integrated joint move simultaneously, the foot performs a compound movement in the plantarflexion-dorsiflexion direction and the inverting / evertating direction.

[0023] 2. This invention uses a linear actuator within the shinbone as the power source for plantar flexion or dorsiflexion of the foot. The output shaft of the linear actuator drives a connecting rod, which in turn pulls the foot in plantar flexion or dorsiflexion. By placing the linear actuator, its output shaft, and the connecting rod within the shinbone, the internal space of the shin can be fully utilized, ensuring that the shape of the shinbone and foot closely resembles that of a real human shin and foot. Furthermore, the linear actuator, its output shaft, and the connecting rod, acting as the skeletal framework of the shin, enhance the supporting force of the shin. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the structure of the present invention; Figure 2 yes Figure 1 A magnified view of a section at point A in the middle; Figure 3 This is a schematic diagram of the structure of the invention in the first direction when the instep is removed; Figure 4 yes Figure 3 A magnified view of a section at point B in the middle; Figure 5 This is a schematic diagram of the second direction of the present invention when the instep is removed; Figure 6 yes Figure 5 A magnified view of a section at point C; Figure 7 This is a cross-sectional view of a harmonic geared motor; Figure 8 This is a partial structural diagram of a harmonic geared motor.

[0025] In the diagram: 1-Shinbone; 2-Foot; 3-Integrated joint; 4-Linear actuator; 5-Output shaft; 6-Drive linkage; 7-Ankle support; 8-Roller follower; 9-Instep; 11-Slide groove; 12-Shinbone body; 13-Supporting parts; 14-Opening slot; a1-Central shaft; a2-Motor stator; a3-Motor rotor; a4-Cam; a5-Flexible wheel; a6-Harmonic rigid wheel; a7-Output flange; a8-Flexible bearing; a9-Rear cover; a10-Rolling bearing; a11-Cross roller bearing. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0027] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention. It should be noted that, unless otherwise specified, the embodiments and features described in the embodiments of the invention can be combined with each other.

[0028] like Figures 1-6As shown, the bionic foot 2 and lower leg structure of this embodiment include a shinbone 1, a foot 2, and an instep 9 fixed on the foot 2. The lower end of the shinbone 1 is rotatably connected to an integrated joint 3. The output end of the integrated joint 3 is fixedly connected to the foot 2. A linear actuator 4 is installed on the shinbone 1. The output shaft 5 of the linear actuator 4 is rotatably connected to a drive link 6. An ankle support 7 is fixed on the housing of the integrated joint 3. The end of the drive link 6 away from the output shaft 5 of the linear actuator 4 is rotatably connected to the ankle support 7.

[0029] Linear actuator 4 serves as the skeletal frame of the lower leg. Linear actuator 4 drives its output shaft 5, and a drive link 6 is rotatably connected to the output shaft 5, adapting to the angle changes when the output shaft 5 extends or retracts. Drive link 6 is rotatably connected to ankle support 7, adapting to the angle changes of drive link 6. Ankle support 7 is connected to integrated joint 3, and the output end of integrated joint 3 is fixedly connected to the foot 2. Ankle support 7 is rotatably connected to the foot 2. When the output shaft 5 of linear actuator 4 extends or retracts, it drives drive link 6 to push the foot 2 in plantarflexion or dorsiflexion. The output end of integrated joint 3 rotates, causing the foot 2 to invert or evert. When linear actuator 4 and integrated joint 3 move simultaneously, the foot 2 performs a compound movement in plantarflexion / dorsiflexion and invert / evertation.

[0030] This invention uses a linear actuator 4 within the shinbone 1 as the power source for plantar flexion or dorsiflexion of the foot 2. The output shaft 5 of the linear actuator 4 drives a drive linkage 6, which in turn pulls the foot 2 in plantar flexion or dorsiflexion. By placing the linear actuator 4, its output shaft 5, and the drive linkage 6 within the shinbone 1, the internal space of the shin can be fully utilized, ensuring that the shape of the shinbone 1 and the foot 2 closely resembles that of a real human shin and foot. Furthermore, the linear actuator 4, its output shaft 5, and the drive linkage 6 serve as the skeletal framework of the shin, enhancing the shin's support strength.

[0031] The lower leg bone 1 is provided with a vertically arranged sliding groove 11. A roller follower 8 is installed on the needle roller bearing between the output shaft 5 of the linear actuator 4 and the drive connecting rod 6. The roller follower 8 is sleeved in the sliding groove 11.

[0032] When the linear actuator 4 is activated, its output shaft 5 rises or falls. At this time, the roller follower 8 always rolls within the sliding space of the tibia 1, thereby ensuring that the roller follower 8 is accurately limited. As a result, the output shaft 5 of the linear actuator 4 and the drive linkage 6 can move more smoothly.

[0033] Furthermore, grooves 11 are provided on both sides of the interior of the shinbone 1. Roller followers 8 are installed at both ends of the needle roller bearing between the output shaft 5 of the linear actuator 4 and the drive link 6, with the two roller followers 8 respectively fitted into the corresponding grooves 11. The roller followers 8 on both sides can further improve the stability of the needle roller bearing here, ensuring smooth operation of the output shaft 5 of the linear actuator 4 and the drive link 6.

[0034] The heel of the foot 2 is rotatably connected to the ankle support 7 via a needle roller bearing. The ankle support 7 not only connects to the drive linkage 6 but also rotatably connects to the heel of the foot 2, thus providing reliable support for the heel of the foot 2. The front of the foot 2 is fixed to the output end of the integrated joint 3, and the rear end of the foot 2 is rotatably connected to the ankle support 7, thereby providing reliable support for both the front and rear of the foot 2 and improving its stability.

[0035] The pin bearing between the heel of the foot 2 and the ankle support 7 is coaxial with the integrated joint 3.

[0036] Since the front part of the foot 2 is fixed to the output end of the integrated joint 3, the axis of rotation of the front part of the foot 2 is coaxial with the axis of the integrated joint 3. Consequently, both the front part of the foot 2 and the heel of the foot 2 are coaxial with the integrated joint 3, ensuring that the foot 2 can rotate reliably when inverting or everting, and avoiding motion interference.

[0037] Specifically, the shinbone 1 includes a shin body 12 and a support part 13 detachably connected to the lower end of the shin body 12. The support part 13 is rotatably connected to the housing of the integrated joint 3 via a needle roller bearing. The support part is connected to the shin body 12 by several bolts for easy disassembly, thereby allowing the foot 2 to be separated from the shinbone 1 for easy assembly and disassembly.

[0038] To avoid interference, an opening groove 14 is provided on the lower part of the posterior side of the tibia 1, from which the drive link 6 extends; the axis of the integrated joint 3 is coplanar with the center line of the drive link 6. The lower end of the drive link 6 extends from the opening groove 14 of the tibia 1 to avoid motion interference between the drive link 6 and the tibia 1 when the drive link 6 moves.

[0039] The axis of the integrated joint 3 is set parallel to the extension direction of the foot 2, and the output end of the integrated joint 3 rotates to drive the foot 2 to turn inward or outward.

[0040] Specifically, such as Figure 7 and Figure 8As shown, the integrated joint 3 is a harmonic reduction motor; the harmonic reduction motor includes a central shaft a1, a motor stator a2 mounted on the central shaft a1, a motor rotor a3 sleeved on the motor stator a2, a cam a4 fixed on the motor rotor a3, a flexible wheel a5 connected to the cam a4 via a flexible bearing a8, a harmonic rigid wheel a6 meshing with the flexible wheel a5, the number of teeth of the flexible wheel a5 being less than the number of teeth of the harmonic rigid wheel a6, an output flange a7 fixed on the flexible wheel a5, the output flange a7 and the flexible wheel a5 being fixed, a rear cover a9 fixed to one end of the central shaft a1, the rear cover a9 being fixed to the harmonic rigid wheel a6; the harmonic rigid wheel a6 is rotatably connected to the shinbone 1, and the output flange a7 is fixedly connected to the foot 2.

[0041] When the motor is powered on, the motor rotor a3 rotates relative to the motor stator a2. The motor rotor a3 drives the cam a4 to rotate, and the cam a4 drives the flexure a5 to mesh with the harmonic rigid wheel a6 through the flexible bearing a8. If the number of teeth of the flexure a5 is N less than the number of teeth of the harmonic rigid wheel a6, then when the cam a4 rotates one revolution, the flexure a5 rotates N teeth relative to the harmonic rigid wheel a6. This results in a greater speed reduction for the output flange a7 connected to the flexure a5, ensuring a stable output force, and ensuring transmission accuracy through gear transmission.

[0042] A rolling bearing a10 is provided between the central shaft a1 and the cam a4; the harmonic reduction motor also includes a crossed roller bearing a11, the inner ring of the crossed roller bearing a11 is integrally formed or fixedly connected to the output flange a7, and the outer ring of the crossed roller bearing a11 is integrally formed or fixedly connected to the harmonic rigid wheel a6.

[0043] This invention is not limited to the above-described optional embodiments. Anyone can derive other various forms of products under the guidance of this invention. However, regardless of any changes made in their shape or structure, any technical solution that falls within the scope of the claims of this invention shall be protected by this invention.

Claims

1. A bionic foot (2) and lower leg structure, characterized in that: It includes a shinbone (1) and a foot (2). The lower end of the shinbone (1) is rotatably connected to an integrated joint (3). The output end of the integrated joint (3) is fixedly connected to the foot (2). A linear actuator (4) is installed on the shinbone (1). The output shaft (5) of the linear actuator (4) is rotatably connected to a drive link (6). An ankle support seat (7) is fixed on the housing of the integrated joint (3). The end of the drive link (6) away from the output shaft (5) of the linear actuator (4) is rotatably connected to the ankle support seat (7).

2. The bionic foot (2) and lower leg structure according to claim 1, characterized in that: The shinbone (1) is provided with a vertically arranged slide groove (11). A roller follower (8) is installed on the needle roller bearing between the output shaft (5) of the linear actuator (4) and the drive link (6). The roller follower (8) is sleeved in the slide groove (11).

3. The bionic foot (2) and lower leg structure according to claim 2, characterized in that: Both sides of the calf bone (1) are provided with sliding grooves (11). Both ends of the needle roller bearing between the output shaft (5) of the linear actuator (4) and the drive link (6) are equipped with roller followers (8). The two roller followers (8) are respectively fitted into the sliding grooves (11) at the corresponding positions.

4. The bionic foot (2) and lower leg structure according to claim 1, characterized in that: The heel of the foot (2) is rotatably connected to the ankle support (7) via a needle roller bearing.

5. A bionic foot (2) and lower leg structure according to claim 4, characterized in that: The pin bearing between the heel of the foot (2) and the ankle support (7) is coaxial with the integrated joint (3).

6. The bionic foot (2) and lower leg structure according to claim 1, characterized in that: The lower leg bone (1) includes a lower leg body (12) and a support part (13) detachably connected to the lower end of the lower leg body (12). The support part (13) is rotatably connected to the housing of the integrated joint (3) via a needle roller bearing.

7. The bionic foot (2) and lower leg structure according to claim 1, characterized in that: The lower part of the posterior side of the tibia (1) is provided with an opening groove (14), and the drive link (6) extends out from the opening groove (14); the axis of the integrated joint (3) is coplanar with the center line of the drive link (6).

8. The bionic foot (2) and lower leg structure according to claim 1, characterized in that: The axis of the integrated joint (3) is set parallel to the extension direction of the foot (2), and the output end of the integrated joint (3) rotates to drive the foot (2) to turn inward or outward.

9. The bionic foot (2) and lower leg structure according to claim 1, characterized in that: The integrated joint (3) is a harmonic speed reducer motor; the harmonic speed reducer motor includes a central shaft (a1), a motor stator (a2) is mounted on the central shaft (a1), a motor rotor (a3) ​​is mounted on the motor stator (a2), a cam (a4) is fixed on the motor rotor (a3), the cam (a4) is connected to a flexible wheel (a5) through a flexible bearing (a8), the flexible wheel (a5) meshes with a harmonic rigid wheel (a6), the number of teeth of the flexible wheel (a5) is less than the number of teeth of the harmonic rigid wheel (a6), an output flange (a7) is fixed on the flexible wheel (a5), the output flange (a7) and the flexible wheel (a5) are fixed, a rear cover (a9) is fixed at one end of the central shaft (a1), the rear cover (a9) is fixed to the harmonic rigid wheel (a6); the harmonic rigid wheel (a6) is rotatably connected to the shinbone (1), and the output flange (a7) is fixedly connected to the foot (2).

10. A bionic foot (2) and lower leg structure according to claim 9, characterized in that: A rolling bearing (a10) is provided between the central shaft (a1) and the cam (a4); the harmonic geared motor also includes a cross roller bearing (a11), the inner ring of the cross roller bearing (a11) is integrally formed or fixedly connected to the output flange (a7), and the outer ring of the cross roller bearing (a11) is integrally formed or fixedly connected to the harmonic rigid wheel (a6).

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