A line-driven bipedal robot leg structure

Abstract

This invention discloses a line-driven bipedal robot leg structure, including a thigh support, a knee joint motor at the lower end of the thigh support, a lower leg support connected to the output shaft of the knee joint motor, and a foot assembly movably connected to the lower end of the lower leg support. The foot assembly includes a foot fixation member, a heel connected to the rear of the foot fixation member, and a line-driven structure connected to the heel. The line-driven structure includes a first ankle joint motor and a second ankle joint motor, a first drive spool, a second drive spool, a first ankle joint spool, and a second ankle joint spool. A first transmission line is provided between the first drive spool and the first ankle joint spool, and a second transmission line is provided between the second drive spool and the second ankle joint spool. A first crank-rocker structure is provided between the first ankle joint spool and one side of the heel, and a second crank-rocker structure is provided between the second ankle joint spool and the other side of the heel. This invention has the advantages of simple structure and good adaptability.

Description

Technical Field

[0001] This invention relates to the field of bipedal robot technology, and more particularly to a leg structure for a wire-driven bipedal robot. Background Technology

[0002] In traditional bipedal robot designs, ankle motors are typically mounted in the lower leg. This design increases the mass and rotational inertia of the lower leg. Greater leg inertia directly impacts the robot's dynamic performance, such as reducing speed and acceleration, and increasing energy consumption. Furthermore, greater leg inertia places higher demands on the robot's balance control system, making it more prone to instability during rapid movements or when subjected to external disturbances, thus limiting its application in complex environments.

[0003] Secondly, existing bipedal robots typically use multiple motors to drive each joint, resulting in a highly complex mechanical structure in the joint areas. This complexity not only increases the robot's manufacturing cost and maintenance difficulty but also makes it prone to mechanical failures. Furthermore, due to limitations in motors and transmission mechanisms, joint stiffness is usually high, making it difficult to achieve smooth and natural movement like that of humans. High-stiffness joints also limit the robot's compliance when interacting with its environment, making it difficult to adapt to uneven terrain or absorb impacts.

[0004] Finally, most traditional bipedal robots have feet with fixed stiffness, which cannot be adjusted according to different ground environments. This makes it difficult for the robots to maintain stability and efficient movement when facing complex terrains, such as soft grass, hard rocks, or uneven roads.

[0005] 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

[0006] The purpose of this invention is to overcome the shortcomings of the prior art and provide a simple and adaptable line-driven bipedal robot leg structure.

[0007] This invention is achieved through the following technical solution:

[0008] To solve the above-mentioned technical problems, the present invention provides a line-driven bipedal robot leg structure, including a thigh support, a knee joint motor at the lower end of the thigh support, a lower leg support connected to the output shaft of the knee joint motor, a foot assembly movably connected to the lower end of the lower leg support, the foot assembly including a foot fixing member universally connected to the lower end of the lower leg support, a heel fixedly connected to the rear of the foot fixing member, and a line-driven structure connected to the heel. The line-driven structure includes a first ankle joint motor and a second ankle joint motor mounted on the thigh support, a first drive sheave mounted on the output shaft of the first ankle joint motor, a second drive sheave mounted on the output shaft of the second ankle joint motor, and a first ankle joint sheave and a second ankle joint sheave rotatably connected to the lower leg support. A first transmission line connects the first drive sheave and the first ankle joint sheave, and a second transmission line connects the second drive sheave and the second ankle joint sheave. A first crank-rocker structure is provided between the first ankle joint sheave and one side of the heel, and a second crank-rocker structure is provided between the second ankle joint sheave and the other side of the heel.

[0009] To further address the technical problem addressed by this invention, the present invention provides a line-driven bipedal robot leg structure in which a first relay wheel and a second relay wheel are provided on the thigh support, the first transmission line passing through the first relay wheel and the second transmission line passing through the second relay wheel.

[0010] To further address the technical problem to be solved by this invention, in the leg structure of a wire-driven bipedal robot provided by this invention, both the first relay wheel and the second relay wheel are coaxial with the output shaft of the knee joint motor.

[0011] To further address the technical problems to be solved by this invention, the present invention provides a line-driven bipedal robot leg structure in which the first crank-rocker structure includes a first eccentric column disposed on a first ankle joint reel and a first shaft head disposed on one side of the heel. A first transmission rod is provided between the first eccentric column and the first shaft head, and both ends of the first transmission rod are provided with first universal connectors for connecting with the first eccentric column or the first shaft head.

[0012] To further address the technical problems to be solved by this invention, the present invention provides a line-driven bipedal robot leg structure in which the second crank-rocker structure includes a second eccentric column disposed on the second ankle joint sheave and a second shaft head disposed on the other side of the heel. A second transmission rod is provided between the second eccentric column and the second shaft head, and both ends of the second transmission rod are provided with second universal connectors for connecting to the second eccentric column or the second shaft head.

[0013] To further address the technical problem to be solved by this invention, the present invention provides a line-driven bipedal robot leg structure in which the first shaft head and the second shaft head are coaxial.

[0014] To further address the technical problems addressed by this invention, the present invention provides a line-driven bipedal robot leg structure in which a universal joint is provided between the foot fixing component and the lower end of the lower leg support for universal connection between the two.

[0015] To further address the technical problem addressed by this invention, the present invention provides a line-driven bipedal robot leg structure in which the foot assembly further includes a foot arch located at the front of a foot fixation member. The front end of the foot arch is rotatably connected to a foot that can swing up and down. The rear end of the foot is rotatably connected to a first connecting rod. The rear end of the first connecting rod is rotatably connected to a second connecting rod and a drive rod. The other end of the second connecting rod is rotatably connected to the foot fixation member. The other end of the drive rod extends upward and is provided with a damping assembly between it and the lower leg.

[0016] To further address the technical problem addressed by this invention, the present invention provides a line-driven bipedal robot leg structure in which the damping assembly includes a third universal joint located at the upper end of a drive rod. A sleeve is connected to the third universal joint, and the sleeve is slidably connected to a lower leg support in the vertical direction. The sleeve contains a damping spring and a piston capable of pressing the damping spring downwards. A rotating rod is connected to the piston, and the rotating rod is fixed relative to the lower leg support.

[0017] To further address the technical problem addressed by this invention, the present invention provides a line-driven bipedal robot leg structure in which the piston and the rotating rod are connected by a thread, and a stiffness-adjusting motor is connected to the rotating rod for driving the rotating rod to rotate and thus driving the piston to rise and fall.

[0018] Compared with the prior art, the present invention has the following advantages:

[0019] 1. This invention effectively reduces leg inertia and improves the robot's movement flexibility and gait stability by moving the ankle joint motor to the thigh and using a wire-driven mechanism to control the ankle joint. Simultaneously, the wire-driven structure simplifies the mechanical structure of the joint area, providing more space for the integration of other sensors or components. Furthermore, the inherent elasticity of the wire-driven system enhances the ankle's cushioning capacity, reduces ground impact, and improves the robot's interaction with the ground, thereby enhancing the robot's adaptability in complex environments.

[0020] 2. The foot assembly of this invention features a variable stiffness foot structure. By adjusting the preload of the damping spring via a motor, the foot stiffness can be adjusted in real time. This design enables the robot to dynamically adjust foot stiffness according to different terrains and task requirements, thereby improving grip and stability on various surfaces, reducing energy consumption, achieving a smoother and more natural gait, and enhancing adaptability to perform various tasks. Attached Figure Description

[0021] The specific embodiments of the present invention will be further described in detail below with reference to the accompanying drawings, wherein:

[0022] Figure 1 This is one of the three-dimensional structural schematic diagrams of the present invention;

[0023] Figure 2 This is an exploded view of the present invention;

[0024] Figure 3 This is a cross-sectional view of the damping component;

[0025] Figure 4 This is an exploded view of the foot components;

[0026] Figure 5 This is a cross-sectional view of the foot components;

[0027] Figure 6 This is a second three-dimensional structural schematic diagram of the present invention (the lower leg support is not shown). Detailed Implementation

[0028] 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.

[0029] like Figures 1 to 6 As shown, this embodiment provides a line-driven bipedal robot leg structure, aiming to solve problems such as large leg inertia, complex joints, and poor foot adaptability in the prior art. The structure mainly includes a thigh support 1, a knee joint motor 2, a lower leg support 3, a foot assembly 4, and a line-driven structure 5.

[0030] The thigh support 1 serves as the main support structure for the robot's legs, with its lower end connected to the knee joint motor 2. The output shaft of the knee joint motor 2 is connected to the lower leg support 3, enabling flexion and extension movements of the knee joint. The lower end of the lower leg support 3 is connected to the foot assembly 4 via a universal joint, providing the foot with a certain degree of posture adjustment capability.

[0031] The foot assembly 4 includes a foot fixation member 41 and a heel 42. The foot fixation member 41 is connected to the lower end of the calf support 3 via a universal joint, ensuring a flexible connection between the foot and the calf. The heel 42 is fixedly connected to the rear of the foot fixation member 41 and serves as the connection point for the wire-driven structure 5.

[0032] The wire-driven structure 5 is the core of this invention. It moves the ankle joint motor to the thigh support 1, thereby reducing the inertia at the end of the leg. The wire-driven structure 5 mainly consists of a first ankle joint motor 51, a second ankle joint motor 52, a first drive reel 511, a second drive reel 521, a first ankle joint reel 53, a second ankle joint reel 54, a first transmission line 55, a second transmission line 56, a first crank-rocker structure 57, and a second crank-rocker structure 58.

[0033] The first ankle joint motor 51 and the second ankle joint motor 52 are respectively mounted on the thigh support 1, and their output shafts are connected to the first drive spool 511 and the second drive spool 521, respectively. A first transmission line 55 connects the first drive spool 511 and the first ankle joint spool 53, and a second transmission line 56 connects the second drive spool 521 and the second ankle joint spool 54. The first ankle joint spool 53 and the second ankle joint spool 54 are rotatably connected to the lower leg support 3. The rotation of the first ankle joint motor 51 and the second ankle joint motor 52 drives the drive spools to rotate, which in turn drives the ankle joint spools to rotate via the transmission lines, ultimately achieving the flexion, extension, inversion, and eversion movements of the foot.

[0034] To convert the rotational motion of the spool into the swinging motion of the foot, this invention also incorporates a crank-rocker structure. A first crank-rocker structure 57 connects the first ankle joint spool 53 to one side of the heel 42, and a second crank-rocker structure 58 connects the second ankle joint spool 54 to the other side of the heel 42. This design allows the ankle joint motor to drive the spool's rotation, which in turn drives the heel 42 via the crank-rocker structure, thus enabling flexible ankle joint movement.

[0035] This embodiment effectively reduces leg inertia and improves the robot's movement flexibility and gait stability by moving the ankle joint motor to the thigh and using a wire-driven mechanism to control the ankle joint. Simultaneously, the wire-driven structure simplifies the mechanical structure of the joint area, providing more space for the integration of other sensors or components. Furthermore, the inherent elasticity of the wire-driven system enhances the ankle's cushioning capacity, reduces ground impact, and improves the robot's interaction with the ground, thereby enhancing the robot's adaptability in complex environments.

[0036] To further optimize the transmission efficiency and layout of the wire drive system, this invention improves the wire drive structure based on the existing embodiments. A first relay pulley 551 and a second relay pulley 561 are provided on the thigh support 1. The first transmission line 55 bypasses the first relay pulley 551, and the second transmission line 56 bypasses the second relay pulley 561. This design can change the direction of the transmission lines, making the layout of the wire drive system more reasonable, avoiding tangling and interference between lines, and allowing for adjustment of the transmission ratio as needed to optimize torque output.

[0037] A more preferred approach is to make the first relay wheel 551 and the second relay wheel 561 coaxial with the output shaft of the knee joint motor 2. This coaxial design can effectively prevent the transmission cable from getting tangled during knee joint movement, ensuring the stability and reliability of the wire drive system.

[0038] The specific implementation of the crank-rocker structure is explained in detail below.

[0039] The first crank-rocker structure 57 consists of the following components: a first eccentric column 531 fixed to the first ankle joint pulley 53, a first axle head 421 disposed on one side of the heel 42, and a first transmission rod 571 connecting the first eccentric column 531 and the first axle head 421. To achieve a flexible rotational connection, the first transmission rod 571 has first universal joints 572, such as ball bearings, at both ends for connection with the first eccentric column 531 and the first axle head 421.

[0040] The second crank-rocker structure 58 is similar to the first crank-rocker structure 57, including: a second eccentric column 541 fixed on the second ankle joint pulley 54, a second shaft head 422 disposed on the other side of the heel 42, and a second transmission rod 581 connecting the second eccentric column 541 and the second shaft head 422. Similarly, the two ends of the second transmission rod 581 are also provided with second universal joints 582, such as ball bearings, for connecting with the second eccentric column 541 and the second shaft head 422.

[0041] This crank-rocker structure design allows the eccentric column to drive the transmission rod as the ankle joint pulley rotates, which in turn causes the heel to rotate around the shaft, enabling the ankle joint to perform pitching and inversion / eversion movements. The use of a universal joint ensures the flexibility of the transmission rod during movement and allows it to adapt to a certain degree of misalignment and deformation, improving the reliability and durability of the mechanism.

[0042] A more preferred approach is to design the first shaft head 421 and the second shaft head 422 as coaxial. This coaxial design effectively simplifies the heel structure, reduces the number of parts, and improves assembly accuracy. Simultaneously, the coaxial design ensures the stability of the heel's rotation center, preventing wobbling or offset, thereby improving the accuracy and stability of ankle joint movement and making torque transmission more efficient.

[0043] The specific implementation of the foot component is explained in detail below.

[0044] The foot assembly 4 includes a foot fixation member 41, which is connected to the lower end of the calf support 3 via a universal joint 43. The universal joint 43 enables the foot assembly to move with multiple degrees of freedom relative to the calf, allowing it to adapt to different terrains and postures.

[0045] An arch 44 is provided at the front of the foot fixation component 41. The arch 44 is typically curved and gradually slopes downward from back to front. The front end of the arch 44 is rotatably connected to the foot ball 45, which can swing up and down. This design simulates the arched structure of the human foot, providing a certain degree of cushioning and support.

[0046] A first connecting rod 46 is provided at the rear of the foot 45. The front end of the first connecting rod 46 is rotatably connected to the foot 45, and the rear end of the first connecting rod 46 is rotatably connected to a second connecting rod 47 and a drive rod 48. The other end of the second connecting rod 47 is rotatably connected to a foot fixing member 41, forming a four-bar linkage. The drive rod 48 extends upward and is connected to the calf support 3 through a damping assembly 49.

[0047] The damping assembly 49 is a key component for achieving variable stiffness. It includes a third universal joint 491 fixed to the upper end of the drive rod 48, a sleeve 492, a damping spring 493, a piston 494, a rotating rod 495, and a stiffness adjustment motor 496. The sleeve 492 slides up and down along the calf support 3, and houses the damping spring 493 and the piston 494. The piston 494 is connected to the rotating rod 495, which is connected to the stiffness adjustment motor 496 via a coupling. The stiffness adjustment motor 496 is fixed to the calf support 3. The piston 494 and the rotating rod 495 are connected by a thread, allowing the piston 494 to move up and down when the rotating rod 495 rotates. By driving the rotating rod 495 to rotate via the stiffness adjustment motor 496, the up-and-down movement of the piston 494 within the sleeve 492 can be controlled, thereby changing the pre-compression of the damping spring 493 and thus adjusting the stiffness of the foot.

[0048] The advantages of this variable stiffness foot structure are:

[0049] 1) Adapting to different terrains: By adjusting the stiffness of its feet, the robot can better adapt to various terrains. On soft ground, reducing stiffness can increase the contact area, improving grip and stability; on hard surfaces, increasing stiffness can ensure efficient force transmission.

[0050] 2) Energy storage and release: The variable stiffness foot can store and release energy like a spring, thereby reducing the energy consumption of the actuator and improving the energy efficiency of the robot's walking.

[0051] 3) Flexible gait: By adjusting the stiffness of the foot, a more flexible gait can be achieved, mimicking the natural movement of living organisms, reducing the adverse effects of ground reaction force, and making the movement smoother.

[0052] 4) Adapt to different task requirements: When moving heavy objects, higher stiffness is required to provide stable support; while when performing delicate or collaborative tasks, stiffness can be reduced to achieve more precise and compliant interaction.

[0053] In summary, this foot component design, especially the variable stiffness structure, significantly improves the robot's environmental adaptability, motion efficiency, and task execution capabilities, enabling it to better cope with complex and ever-changing application scenarios.

Claims

1. A leg structure for a wire-driven bipedal robot, characterized in that: The system includes a thigh support (1), a knee joint motor (2) at the lower end of the thigh support (1), a calf support (3) connected to the output shaft of the knee joint motor (2), a foot assembly (4) movably connected to the lower end of the calf support (3), the foot assembly (4) including a foot fixing member (41) universally connected to the lower end of the calf support (3), a heel (42) fixedly connected to the rear of the foot fixing member (41), and a wire drive structure (5) connected to the heel (42). The wire drive structure (5) includes a first ankle joint motor (51) and a second ankle joint motor (52) mounted on the thigh support (1), a first drive wheel (511) mounted on the output shaft of the first ankle joint motor (51), and a drive wheel (511) mounted on the output shaft of the first ankle joint motor (51). The output shaft of the second ankle joint motor (52) is provided with a second drive wheel (521), a first ankle joint wheel (53) and a second ankle joint wheel (54) rotatably connected to the calf support (3), and a first transmission line (55) connecting the first drive wheel (511) and the first ankle joint wheel (53) is provided. A second transmission line (56) connecting the second drive wheel (521) and the second ankle joint wheel (54) is provided. A first crank-rocker structure (57) is provided between the first ankle joint wheel (53) and one side of the heel (42), and a second crank-rocker structure (58) is provided between the second ankle joint wheel (54) and the other side of the heel (42).

2. The leg structure of a wire-driven bipedal robot according to claim 1, characterized in that: The thigh support (1) is provided with a first relay wheel (551) and a second relay wheel (561). The first transmission line (55) passes through the first relay wheel (551), and the second transmission line (56) passes through the second relay wheel (561).

3. The leg structure of a wire-driven bipedal robot according to claim 2, characterized in that: The first relay pulley (551) and the second relay pulley (561) are both coaxial with the output shaft of the knee joint motor (2).

4. The leg structure of a wire-driven bipedal robot according to claim 1, characterized in that: The first crank lever structure (57) includes a first eccentric column (531) on the first ankle joint pulley (53) and a first shaft head (421) on the side of the heel (42). A first transmission rod (571) is provided between the first eccentric column (531) and the first shaft head (421). Both ends of the first transmission rod (571) are provided with a first universal connector (572) for connecting with the first eccentric column (531) or the first shaft head (421).

5. The leg structure of a wire-driven bipedal robot according to claim 4, characterized in that: The second crank lever structure (58) includes a second eccentric column (541) on the second ankle joint pulley (54) and a second shaft head (422) on the other side of the heel (42). A second transmission rod (581) is provided between the second eccentric column (541) and the second shaft head (422). Both ends of the second transmission rod (581) are provided with a second universal connector (582) for connecting to the second eccentric column (541) or the second shaft head (422).

6. The leg structure of a wire-driven bipedal robot according to claim 5, characterized in that: The first shaft head (421) and the second shaft head (422) are coaxial.

7. The leg structure of a wire-driven bipedal robot according to claim 1, characterized in that: A universal joint (43) for universally connecting the foot fixing member (41) and the lower end of the calf support (3) is provided.

8. The leg structure of a wire-driven bipedal robot according to claim 1, characterized in that: The foot assembly (4) also includes an arch (44) located at the front of the foot fixation member (41). The front end of the arch (44) is rotatably connected to a foot (45) that can swing up and down. The rear end of the foot (45) is rotatably connected to a first connecting rod (46). The rear end of the first connecting rod (46) is rotatably connected to a second connecting rod (47) and a drive rod (48). The other end of the second connecting rod (47) is rotatably connected to the foot fixation member (41). The other end of the drive rod (48) extends upward and is provided with a damping assembly (49) between it and the lower leg.

9. The leg structure of a wire-driven bipedal robot according to claim 8, characterized in that: The damping assembly (49) includes a third universal joint (491) located at the upper end of the drive rod (48). A sleeve (492) is connected to the third universal joint (491). The sleeve (492) is slidably connected to the calf support (3) in the vertical direction. A damping spring (493) and a piston (494) that can push down the damping spring (493) are provided in the sleeve (492). A rotating rod (495) is connected to the piston (494). The rotating rod (495) is fixed relative to the calf support (3).

10. The leg structure of a wire-driven bipedal robot according to claim 9, characterized in that: The piston (494) and the rotating rod (495) are connected by a thread, and a stiffness adjustment motor (496) is connected to the rotating rod (495) for driving the rotating rod (495) to rotate and thus driving the piston (494) to rise and fall.

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