A variable stiffness foot structure for a bipedal robot

Abstract

This invention discloses a variable stiffness foot structure for a bipedal robot, including a lower leg support and a foot fixation component. A heel is fixedly connected to the rear of the foot fixation component, and axle heads are provided on both sides of the heel. An ankle joint drive device is movably connected to each axle head. An arch is fixedly connected to the front of the foot fixation component, and a foot is rotatably connected to the front end of the arch. A first link is rotatably connected to the rear end of the foot. A second link and a third link are rotatably connected to the other end of the first link. The other end of the second link is rotatably connected to the foot fixation component, and the other end of the third link is rotatably connected to a damping assembly. The damping assembly includes a sleeve, a damping spring disposed within the sleeve, and a piston slidably connected within the sleeve and capable of pressing against the damping spring. An adjusting rod is connected to the piston, and the adjusting rod is fixed relative to the lower leg support. A stiffness adjustment device is provided between the adjusting rod and the piston. This invention has the advantages of being more flexible, efficient, and adaptable.

Description

Technical Field

[0001] This invention relates to the field of bipedal robot technology, and more particularly to a variable stiffness foot structure for a bipedal robot. Background Technology

[0002] The design of the feet for bipedal robots has always been a key focus and challenge in the field of robotics. Traditional foot designs typically only achieve fixed stiffness and cannot dynamically adjust to changes in the environment and task. Therefore, traditional fixed-stiffness feet are poorly adaptable to complex terrains and tasks. For example, on soft ground, rigid feet tend to sink, resulting in insufficient grip and decreased stability; while on hard surfaces, rigid feet generate significant ground reaction forces, affecting the smoothness of movement and energy efficiency.

[0003] Therefore, it is necessary to further improve and refine the existing technology to overcome these shortcomings, and this invention is made based on this situation. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide a more flexible, efficient, and adaptable variable stiffness foot structure for bipedal robots.

[0005] This invention is achieved through the following technical solution:

[0006] To address the aforementioned technical problems, this invention provides a variable stiffness foot structure for a bipedal robot, comprising a lower leg support and a foot fixation component universally connected to the lower end of the lower leg support. A heel is fixedly connected to the rear of the foot fixation component, and axle heads are provided on both sides of the heel. An ankle joint drive device is movably connected to each of the two axle heads. An arch is fixedly connected to the front of the foot fixation component, and a foot capable of vertical movement is rotatably connected to the front end of the arch. A first link is rotatably connected to the rear end of the foot. A second link and a third link are rotatably connected to the other end of the first link. The other end of the second link is rotatably connected to the foot fixation component. The other end of the third link extends upward and is rotatably connected to a damping assembly. The damping assembly includes a sleeve connected to the third link and slidably connected to the lower leg support, a damping spring disposed in the sleeve, and a piston slidably connected in the sleeve and capable of pressing against the damping spring. An adjusting rod is connected to the piston, and the adjusting rod is fixed relative to the lower leg support. A stiffness adjustment device for adjusting the piston position is provided between the adjusting rod and the piston.

[0007] To further address the technical problem addressed by this invention, the present invention provides a variable stiffness foot structure for a bipedal robot. The stiffness adjustment device includes a stiffness adjustment motor mounted on a lower leg support. The output shaft of the stiffness adjustment motor and an adjustment rod are connected via a coupling, and the adjustment rod and a piston are connected by a thread. When the adjustment rod rotates, the piston rises and falls within a sleeve, thereby adjusting the degree of pre-compression of the piston's damping spring.

[0008] To further address the technical problem to be solved by this invention, the present invention provides a variable stiffness foot structure for a bipedal robot, wherein a first universal joint connecting the upper end of the sleeve and the third link is provided.

[0009] To further address the technical problem to be solved by this invention, this invention provides a variable stiffness foot structure for a bipedal robot, wherein the sleeve is arranged in the vertical direction, and the third link has a curved shape that extends backward first, then upward and forward.

[0010] To further address the technical problem to be solved by this invention, the present invention provides a variable stiffness foot structure for a bipedal robot, wherein the foot is hollow.

[0011] To further address the technical problem addressed by this invention, the present invention provides a variable stiffness foot structure for a bipedal robot, wherein the foot arches are provided on the left and right sides and are distributed in a figure-eight shape, and the foot arches are both arcs that gradually decrease from back to front.

[0012] To further address the technical problem addressed by this invention, the present invention provides a variable stiffness foot structure for a bipedal robot, wherein each foot arch has a vertical pin at its front end, a rotating shaft is provided between the two pins, and the rotating shaft has shaft holes at both ends that can be inserted into the corresponding pins, and the rear end of the foot is rotatably connected to the rotating shaft.

[0013] To further address the technical problem addressed by this invention, the present invention provides a variable stiffness foot structure for a bipedal robot, wherein the ankle joint driving device includes a turntable rotatably connected to a lower leg support, an eccentric shaft is provided on the turntable, a transmission rod is provided between the eccentric shaft and a corresponding shaft head, and both ends of the transmission rod are provided with a second universal joint for connecting the corresponding eccentric shaft or the corresponding shaft head, and the turntable is connected to an ankle joint actuator for driving its rotation.

[0014] To further address the technical problem to be solved by this invention, this invention provides a variable stiffness foot structure for a bipedal robot in which the axle heads on both sides of the heel are coaxial.

[0015] To further address the technical problem to be solved by this invention, the present invention provides a variable stiffness foot structure for a bipedal robot, wherein a universal joint is provided between the lower leg support and the foot fixing component for universal connection between the two.

[0016] Compared with the prior art, the present invention has the following advantages:

[0017] This invention relates to a bipedal robot with variable stiffness feet, integrating a variable stiffness foot structure, a flexible ankle joint, and a stiffness adjustment device. Through damping components, a closed-loop linkage mechanism, and a motor-driven stiffness adjustment rod, the robot can dynamically adjust the foot stiffness according to different terrains and task requirements, thereby improving its adaptability, stability, movement efficiency, and safety in various ground environments, and achieving a more natural gait. Attached Figure Description

[0018] The specific embodiments of the present invention will be further described in detail below with reference to the accompanying drawings, wherein:

[0019] Figure 1 This is one of the three-dimensional structural schematic diagrams of the present invention;

[0020] Figure 2 This is an exploded diagram of the foot;

[0021] Figure 3 This is a cross-sectional view of the foot;

[0022] Figure 4 This is a cross-sectional schematic diagram of the damping component;

[0023] Figure 5 This is the second three-dimensional structural schematic diagram of the present invention. Detailed Implementation

[0024] To enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0025] This invention provides a bipedal robot with variable stiffness feet, which can effectively improve the robot's adaptability and mobility in different terrains.

[0026] like Figures 1 to 5 As shown, the variable stiffness foot structure of the bipedal robot mainly includes the following components: the lower leg support 1 serves as the supporting base of the foot structure; the foot fixing component 2 is connected to the lower end of the lower leg support 1 through a universal connection, so that the foot has a certain spatial posture adjustment capability; the heel 3 is fixedly connected to the rear of the foot fixing component 2, and axle heads 31 are respectively set on its left and right sides for connecting the ankle joint drive device 4 to realize the flexible rotation of the ankle joint.

[0027] An arch 5 is provided at the front of the foot, and the arch 5 is fixedly connected to the foot fixing member 2. Its front end is connected to the foot ball 6, which can swing up and down, through a rotating connection structure. The rear end of the foot ball 6 is connected to the first link 61 through a rotating connection structure. The other end of the first link 61 is rotatably connected to the second link 21 and the third link 7. The other end of the second link 21 is rotatably connected to the foot fixing member 2, forming a closed-loop linkage mechanism, which makes the movement of the foot ball more stable and controllable. The other end of the third link 7 extends upward and is rotatably connected to the damping component 8.

[0028] The design of the damping assembly 8 is the core of achieving variable foot stiffness. This assembly includes a sleeve 81, a damping spring 82, a piston 83, and an adjusting rod 84. The sleeve 81 is connected to the third link 7 and can slide along the lower leg support 1. The damping spring 82 is disposed inside the sleeve 81. The piston 83 is slidably connected inside the sleeve 81 and can press against the damping spring 82 to adjust the foot stiffness. The piston 83 is connected to the adjusting rod 84, which is fixed relative to the lower leg support 1.

[0029] To precisely control foot stiffness, this invention further employs a stiffness adjustment device 85. This device includes a stiffness adjustment motor 851 mounted on the calf support 1. The output shaft of the stiffness adjustment motor 851 is connected to an adjusting rod 84 via a coupling, and the adjusting rod 84 and the piston 83 are connected by a thread. When the stiffness adjustment motor 851 operates, it drives the adjusting rod 84 to rotate, which in turn drives the piston 83 to move up and down within the sleeve 81, thereby changing the degree of pre-compression of the damping spring 82 by the piston 83, achieving continuous adjustment of foot stiffness. The greater the degree of pre-compression of the damping spring 82, the greater the foot stiffness, and vice versa.

[0030] Through the aforementioned structural design, this variable stiffness foot can dynamically adjust its stiffness characteristics according to different terrains and task requirements. For example, on soft ground, reducing foot stiffness increases the contact area between the sole and the ground, improving grip and stability and preventing foot sinking; while on hard surfaces, increasing foot stiffness ensures the effective transmission of ground reaction forces, achieving efficient movement. Furthermore, the variable stiffness design facilitates the storage and release of energy during walking, similar to the elastic tendon mechanism in organisms, thereby improving energy efficiency and achieving a more natural gait. When carrying heavy objects, higher stiffness provides the necessary support; while when performing delicate operations or human-machine collaborative tasks, lower stiffness enhances compliance and improves safety.

[0031] To further enhance the flexibility, adaptability, and stability of the foot, the present invention has made several improvements based on the above embodiments:

[0032] First, to enable the damping assembly 8 to better adapt to the posture changes of the foot during complex movements, a first universal joint 71 is added between the upper end of the sleeve 81 and the third link 7. This universal joint connects the sleeve 81 and the third link 7, allowing for a certain angle of relative rotation between them. This avoids motion interference or stress concentration that may occur with traditional fixed connections, improves the reliability and service life of the mechanism, and enhances the foot's adaptability to irregular terrain.

[0033] Secondly, to optimize the mechanical performance and spatial layout of the foot structure, the sleeve 81 is arranged vertically, while the third link 7 is designed as a curved shape that extends backward first, then upward and forward. This link configuration, combined with the universal joint, allows the foot to deform more smoothly during movement, while effectively transferring the ground impact force to the damping component 8, achieving energy absorption and release; in addition, it can reduce space occupation, making the layout more reasonable and the structure more compact.

[0034] To reduce foot weight and improve breathability, the foot 6 features a hollow design. This design effectively reduces the overall weight of the foot without compromising its structural strength, thereby improving the robot's movement efficiency and enhancing heat dissipation.

[0035] To enhance foot support and stability, this invention designs two arches 5 arranged in a figure-eight shape. Each arch 5 has an arc that gradually decreases from back to front. This biomimetic design simulates the structure of the human foot arch, effectively distributing pressure on the sole of the foot, improving the foot's load-bearing capacity and stability, and enhancing adaptability to different terrains.

[0036] To enable flexible rotation of the foot 6, a vertical pin 51 is provided at the front end of each arch 5. A pivot 52 is provided between two pins 51, with shaft holes 521 at both ends that can be inserted into the corresponding pins 51. The rear end of the foot 6 is fixed to the pivot 52 via a rotatable connection. This design gives the foot 6 additional pitch freedom, allowing it to swing flexibly around the pivot 52, enabling it to better conform to uneven ground and adapt to terrain changes. At the same time, the vertical pin 51 structure can effectively buffer the impact force from the ground, especially under high impact conditions. Even if the pivot 52 undergoes slight deformation, the pin 51 can maintain the stability of the connection, thereby protecting the foot structure and ensuring the stability of the robot's movement.

[0037] To make the connection between the foot and the lower leg support 1 more flexible, a universal joint 9 is provided between the lower leg support 1 and the foot fixing component 2. The universal joint 9 realizes the universal connection between the lower leg support 1 and the foot fixing component 2, giving the foot greater freedom of movement, enabling it to move in more complex three-dimensional space, thereby improving the robot's movement ability and stability in various terrains.

[0038] Each ankle joint drive device 4 includes a turntable 41 rotatably connected to the lower leg support 1. Each turntable 41 is equipped with an eccentric shaft 411. The eccentric shaft 411 converts the rotational motion of the turntable 41 into the swinging motion of the heel 3. Specifically, the eccentric shaft 411 is connected to the corresponding shaft ends 31 on both sides of the heel 3 via transmission rods 42. Each transmission rod 42 has a second universal joint 421 (such as a ball bearing) at both ends for connecting the corresponding eccentric shaft 411 and shaft end 31 respectively. This universal joint design ensures that the transmission rod 42 can flexibly adapt to angle changes during foot movement, avoiding motion interference and ensuring smooth power transmission. The turntable 41 is driven to rotate by an ankle joint actuator, for example, a motor can be used as the actuator, thereby driving the eccentric shaft 411, transmission rods 42, and the shaft ends 31 of the heel 3 to move, ultimately achieving flexible rotation of the ankle joint.

[0039] To further simplify the structure and improve motion efficiency, the axle heads 31 on both sides of the heel 3 are preferably designed to be coaxial. This coaxial design allows the two axle heads 31 to share the same axis of rotation, reducing the number of parts and simplifying the assembly process. More importantly, the coaxial design simplifies the mechanical model and facilitates coordinated control of the movements on both sides, thereby improving the synchronization and stability of ankle joint movements and avoiding potential motion deviations and energy losses. This is crucial for bipedal robots to maintain balance and achieve a stable gait.

[0040] Through the design of the ankle joint actuator described above, combined with the variable stiffness foot structure, the bipedal robot of this invention can more flexibly adapt to various complex terrains, achieving a more stable, efficient, and natural walking gait. The ankle joint actuator, combined with the transmission mechanism of an eccentric shaft and a drive rod, enables precise adjustment of the foot posture, thereby enhancing the robot's adaptability and motion performance in different ground environments. For example, on uneven ground, the robot can maintain its balance by adjusting the angle of the ankle joint, while flexible ankle rotation is also crucial in scenarios such as going up or down slopes or stairs.

Claims

1. A variable stiffness foot structure for a bipedal robot, characterized in that: The device includes a calf support (1) and a foot fixation device (2) universally connected to the lower end of the calf support (1). The foot fixation device (2) is fixedly connected to the rear of the heel (3). The heel (3) is provided with a shaft head (31) on both the left and right sides. An ankle joint drive device (4) is movably connected to both shaft heads (31). The foot fixation device (2) is fixedly connected to the front of the foot arch (5). The front end of the foot arch (5) is rotatably connected to the foot ball (6) which can swing up and down. The rear end of the foot ball (6) is rotatably connected to the first link (61). The other end of the first link (61) is rotatably connected to the second link (21) and the third link (7). The other end of the second link (21) is rotatably connected to the foot fixation device (2). The other end of the third link (7) extends upward and is rotatably connected to the damping component (8) with adjustable damping size. The damping assembly (8) includes a sleeve (81) connected to the third link (7) and slidably connected to the lower leg support (1), a damping spring (82) disposed in the sleeve (81), and a piston (83) slidably connected in the sleeve (81) and capable of pressing the damping spring (82). An adjusting rod (84) is connected to the piston (83), and the adjusting rod (84) is fixed relative to the lower leg support (1). A stiffness adjusting device (85) for adjusting the position of the piston (83) is provided between the adjusting rod (84) and the piston (83). The stiffness adjustment device (85) includes a stiffness adjustment motor (851) mounted on the lower leg support (1). The output shaft of the stiffness adjustment motor (851) and the adjustment rod (84) are connected by a coupling, and the adjustment rod (84) and the piston (83) are connected by a thread. When the adjustment rod (84) rotates, the piston (83) moves up and down in the sleeve (81), thereby adjusting the degree of pre-compression of the damping spring (82) by the piston (83).

2. The variable stiffness foot structure for a bipedal robot according to claim 1, characterized in that: A first universal joint (71) is provided between the upper end of the sleeve (81) and the third link (7) to connect the two.

3. The variable stiffness foot structure for a bipedal robot according to claim 1, characterized in that: The sleeve (81) is arranged in the vertical direction, and the third link (7) has a curved shape that extends backward first and then upward and forward.

4. The variable stiffness foot structure for a bipedal robot according to claim 1, characterized in that: The sole (6) is hollowed out.

5. The variable stiffness foot structure for a bipedal robot according to claim 1, characterized in that: The foot arch (5) has two parts, left and right, arranged in a figure-eight shape. The foot arch (5) is an arc shape that gradually decreases from back to front.

6. The variable stiffness foot structure for a bipedal robot according to claim 5, characterized in that: The front end of each foot arch (5) is provided with a vertical pin (51), and a rotating shaft (52) is provided between the two pins (51). The two ends of the rotating shaft (52) are provided with shaft holes (521) that can be inserted into the corresponding pins (51). The rear end of the foot (6) is rotatably connected to the rotating shaft (52).

7. The variable stiffness foot structure for a bipedal robot according to claim 1, characterized in that: The ankle joint drive device (4) includes a turntable (41) rotatably connected to the calf support (1). An eccentric shaft (411) is provided on the turntable (41). A transmission rod (42) is provided between the eccentric shaft (411) and the corresponding shaft head (31). Both ends of the transmission rod (42) are provided with a second universal connector (421) for connecting the corresponding eccentric shaft (411) or the corresponding shaft head (31). The turntable (41) is connected to an ankle joint actuator for driving its rotation.

8. The variable stiffness foot structure of a bipedal robot according to claim 1, characterized in that: The shaft heads (31) on both sides of the heel (3) are coaxial.

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