Bird claw imitating actuator with bending and twisting combined joints

Abstract

The invention discloses a bird-claw-imitating actuator with a bending and twisting combined joint, and relates to the technical field of soft robots, the bird-claw-imitating actuator comprises a sole, toes are hinged to the sole, each toe comprises a connecting toe joint, two attaching toe joints and a claw toe joint, the middle parts of the connecting toe joint, the two attaching toe joints and the claw toe joint are sequentially connected through flexible joints, and the connecting toe joint is connected with the two attaching toe joints through flexible joints. The upper surfaces of the connecting toe joint, the two attachment toe joints and the claw toe joint are sequentially connected through reset springs, and pins are installed in the connecting toe joint, the two attachment toe joints and the claw toe joint. According to the bird claw imitating actuator with the bending and twisting combined joints, a composite adhesion mechanism is formed through vacuum adsorption and dry adhesion materials, adaptability is high, and adhesive force is large; and low-power-consumption self-locking is achieved by means of a worm and gear structure, and the device has good dynamic stability and engineering controllability and is suitable for man-machine interaction, robot surface operation and intelligent attachment systems in various complex environments.

Description

Technical Field

[0001] The present invention relates to the technical field of soft robots, and in particular to a bird claw-like actuator with a bending-torsion combined joint. Background Art

[0002] Anatomical studies of bird claw structures have shown that bird grasping movements are primarily achieved through the contraction of the flexor tendons (which connect the upper limb muscles to the toes). This mechanism, based on the combination of active drive and passive linkage based on tendon interlocking, enables bird claws to reliably grasp branches or objects of varying sizes and shapes. Existing bird claw actuators draw on the structural characteristics of bird claws and simulate tendon-driven underactuated systems through ropes. Although these actuators possess certain environmental adaptability and self-locking properties, the toe joints lack torsional freedom, making them unable to twist along the axial and normal directions of the fingers. Furthermore, the toe joints of the bird claw actuators have a small contact area with various irregular surfaces, making them less adaptable to complex structures.

[0003] Current gecko-like microstructured adhesive materials can adhere tightly to target surfaces through their micron-scale structures, generating stable adhesion. However, this process requires pre-established normal adhesion. Meanwhile, vacuum adsorption technology generates rapid and sustained normal adhesion through a pressure differential between the inside and outside of the suction cup. While most current flexible adhesives based on vacuum adsorption technology have a certain degree of adhesion, they suffer from low load-bearing capacity and cannot maintain stable operation in dynamic or complex environments.

[0004] In summary, existing attachment technologies either focus on active driving but lack adaptability, or rely on vacuum adsorption but have limited load-bearing capacity. It is still difficult to take into account efficient grasping, adaptability to complex surfaces and high load-bearing capacity.

[0005] Therefore, there is an urgent need for a new actuator that combines a rigid-flexible coupling structure and a composite attachment mechanism to achieve the synergistic advantages of bionic bird claws and multiple attachment methods such as micro-nano adhesion and vacuum adsorption, so that the attachment operation can be completed stably and efficiently in both conventional and extreme environments. Summary of the Invention

[0006] The purpose of the present invention is to provide a bird claw actuator with a bending and torsion combined joint to solve the problems listed in the background technology.

[0007] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0008] The present invention provides a bird claw-like actuator with a bending-torsion combined joint, comprising a sole, with multiple toes hinged on the sole, each of the toes comprising a connecting toe segment, two attached toe segments, and a hook toe segment, the middle parts of the connecting toe segment, the two attached toe segments, and the hook toe segment being connected in sequence via a flexible joint, the upper surfaces of the connecting toe segment, the two attached toe segments, and the hook toe segment being connected in sequence via a return spring, and pins being installed in the interiors of the connecting toe segment, the two attached toe segments, and the hook toe segment.

[0009] Preferably, it also includes a main pull rope, one end of which is fixedly connected to the pin at the toe joint of the hook claw, the middle part of the main pull rope is wrapped around and connected to the remaining pins, and the other end of the main pull rope is connected to the control rope through a ring structure.

[0010] Preferably, there are two main pull ropes, and the two main pull ropes are respectively located at two ends of the pin.

[0011] Preferably, the attached toe segment includes a bionic flexible attachment actuator, a toe segment body and a trachea, the bionic flexible attachment actuator is connected to the toe segment body by a pin limiter, the bionic flexible attachment actuator is connected to one end of the trachea, and the other end of the trachea is connected to an external air source.

[0012] Preferably, the bionic flexible attachment actuator comprises a vacuum adsorption layer and a dry adhesion layer, and the vacuum adsorption layer and the dry adhesion layer are connected via a rigid connection hardware;

[0013] The vacuum adsorption layer is bonded to the attachment body.

[0014] Preferably, the vacuum adsorption layer adopts an industrial vacuum suction cup, and the dry adhesion layer imitates a gecko bristle array.

[0015] Preferably, the flexible joint is integrally cast using a gradient hardness PDMS material.

[0016] Preferably, the return spring is a shape memory alloy coil spring.

[0017] Compared with the prior art, the present invention has the following beneficial technical effects:

[0018] The present invention discloses a bird claw-like actuator with a bending and torsion combined joint. By imitating the structure of bird claws, it combines flexible joints, a rope drive system and a composite attachment to form a multi-degree-of-freedom attachment device suitable for complex surfaces. The actuator as a whole is composed of a sole and four toes. Each toe is connected by multiple toe joints and flexible joints, and has passive deformation capabilities such as twisting, bending and flipping; and realizes three-dimensional posture adjustment through "flexible joint + rope differential drive"; forms a composite attachment mechanism through "vacuum adsorption + dry adhesive material", with strong adaptability and large adhesion; and uses a worm gear structure to achieve low-power self-locking, with good dynamic stability and engineering controllability, and is suitable for human-computer interaction, robot surface operations and intelligent attachment systems in a variety of complex environments. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The present invention will be further described below with reference to the accompanying drawings.

[0020] Figure 1 This is a schematic diagram of the overall structure of a bird claw-like actuator with a bending and torsion combined joint according to the present invention;

[0021] Figure 2 This is a schematic diagram of the decomposition of a single toe of the present invention;

[0022] Figure 3 This is a schematic diagram of the main pull rope arrangement of the present invention;

[0023] Figure 4 This is a schematic diagram of the control rope arrangement of the present invention;

[0024] Figure 5 Schematic diagram of the flexible joint structure of the present invention;

[0025] Figure 6 This is a schematic diagram of the decomposition of a single attachment toe segment structure of the present invention;

[0026] Figure 7 This is a schematic diagram of the decomposition structure of the bionic flexible attachment device of the present invention;

[0027] Figure 8 This is a schematic diagram of the toe joint degrees of freedom of the present invention;

[0028] Figure 9 This is a schematic diagram of the deformation of the flexible joint under load;

[0029] Figure 10 Schematic diagram A of the working state of the toe of the present invention;

[0030] Figure 11 Schematic diagram B of the working state of the toe of the present invention.

[0031] Explanation of reference numerals: 1, toe; 1-1, connecting toe joint; 1-2, attachment toe joint; 1-3, hook toe joint; 1-4, flexible joint; 1-5, return spring; 1-6, pin; 1-7, main pull rope; 1-8, control rope;

[0032] 1-2-1, bionic flexible attachment actuator; 1-2-2, toe segment body; 1-2-3, trachea;

[0033] 1-2-1-1, vacuum adsorption layer; 1-2-1-2, dry adhesive layer; 1-2-1-3, applicator body;

[0034] 2. Soles of the feet. DETAILED DESCRIPTION

[0035] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0036] like Figure 1-11 As shown, a bird claw actuator with a bending and twisting joint is modeled after the anatomical structure of birds in nature. The overall structure consists of four toes 1 connected to the sole 2 through flexible joints 1-4;

[0037] like Figure 2-4 As shown, the toes are mainly divided into a connecting segment 1-1, two attachment segments 1-2, and a hook segment 1-3. The middle parts of the segments are connected in sequence by flexible joints 1-4, and the upper parts are connected in sequence by reset springs 1-5. The hook segments 1-3 are curved hook-shaped structures that can be used to hook onto the raised edges or crevices of the target surface to assist in gripping and improve attachment stability. The flexible joints 1-4 are integrally cast from PDMS material and have good flexibility and elasticity. The through holes on both sides are connected to the two adjacent segments using fasteners, allowing the toes to bend and twist along the axial direction and twist in the normal direction of the fingers when subjected to external forces. The reset springs 1-5 are fixed at both ends to the flexible joints 1-4. By changing the stiffness of the flexible joints, the reset speed of the flexible joints 1-4 after deformation is increased, thereby achieving chain deformation.

[0038] It also includes a main pull rope 1-7, one end of which is fixedly connected to the pin 1-6 at the hook toe joint 1-3, the middle part of the main pull rope 1-7 is wound and connected with the remaining pins 1-6, and the other end of the main pull rope 1-7 is connected to the control rope 1-8 through a ring structure, so as to actively control the movement of the toes; the two ends of the main pull rope 1-7 pass through the pins 1-6 on each toe joint and are finally fixed to the hook toe joint, so as to stretch the toes as a whole to achieve a grasping action; the control rope 1-8 passes through the main pull ropes on both sides and balances the forces on the ropes on both sides through the ring structure;

[0039] When the main pull rope is pulled, the toes contract and bend toward the claws to complete basic grasping; when the control rope is pulled, the lengths of the main pull ropes on both sides change synchronously - one side of the rope becomes longer and the other side shortens synchronously - causing the toes to twist and bend, and automatically adjust their posture to fit the uneven surface to the greatest extent. By reasonably coordinating the pulling of the main pull rope and the control rope, efficient grasping and rapid detachment of the toes can be achieved; for example, when pulling the control rope, the toes can be axially turned outward, simulating the detachment action of the gecko's toes, and achieving rapid detachment. The force-balanced layout of the control rope ensures stable force on the toes, allowing each toe to automatically adjust its angle according to the contour of the target surface, thereby obtaining the maximum contact area and attachment stability. Control ropes 1-6 are connected to an external worm gear drive motor.

[0040] like Figure 6 As shown, the attached toe segment 1-2 includes a bionic flexible attachment actuator 1-2-1, a toe segment body 1-2-2 and a trachea 1-2-3. The bionic flexible attachment actuator 1-2-1 is connected to the toe segment body 1-2-2 by a pin limiter. The bionic flexible attachment actuator 1-2-1 is connected to one end of the trachea 1-2-3, and the other end of the trachea 1-2-3 is connected to an external air source to provide pressure changes for the bionic flexible attachment 1-2-1.

[0041] like Figure 7 As shown, the bionic flexible attachment actuator 1-2-1 includes a vacuum adsorption layer 1-2-1-1 and a dry adhesion layer 1-2-1-2, simulating the layered structure of a gecko's toes. The vacuum adsorption layer 1-2-1-1 and the dry adhesion layer 1-2-1-2 are connected by rigid connection hardware to ensure a firm structure and maintain airtightness;

[0042] To ensure airtightness, the vacuum adsorption layer 1-2-1-1 is bonded to the attachment body 1-2-1-3;

[0043] The vacuum adsorption layer 1-2-1-1 adopts an industrial vacuum suction cup, which is fixed on the attachment body 1-2-1-3 by gluing and mechanical installation, and is connected to the air pipe 1-2-3 through an external air source to form negative pressure adsorption. The dry adhesive layer 1-2-1-2 imitates the gecko bristle array with a density of 10 5 root / mm 2 , a tapered column with an aspect ratio of 5:1, based on the gecko toe adhesion principle, closely adheres to the attachment surface through van der Waals force;

[0044] During operation, an external air pump evacuates the adsorption layer, causing the suction cup to fit against the target surface to form a sealed negative pressure, generating a continuous normal adsorption force; at the same time, the preload applied by the suction cup makes the dry adhesion layer fully adhere to the surface, improving the overall adhesion friction and load-bearing capacity; this layered structure corresponds to the "rigid skeleton-flexible film" structure of the gecko's toes. Through the organic combination of the adsorption layer (rigid skeleton) and the adhesion layer (flexible film layer), a composite adhesion effect with both strong normal adsorption force and microscopic adhesion force is achieved.

[0045] Specifically, the flexible joints 1-4 are integrally cast using a gradient hardness PDMS material with a gradual change in Shore A from 30° to 70°.

[0046] Specifically, the return spring 1-5 is a shape memory alloy coil spring with a phase change temperature of 45°C±2°C and an adjustable preload range of 0.5 to 5N.

[0047] Working principle:

[0048] The bird claw-like attachment actuator of the present invention imitates the structure of bird claws and combines flexible joints, a rope drive system and a composite attachment to form a multi-degree-of-freedom attachment device suitable for complex surfaces. The actuator is composed of a sole and four toes. Each toe is connected by multiple toes and flexible joints, and has passive deformation capabilities such as twisting, bending and flipping.

[0049] When performing an attach operation, the executor goes through the following workflow:

[0050] Initial standby stage: the toes are naturally open, the posture is maintained by the return spring and flexible joint, the attachment does not touch the target surface, and the control system is in standby;

[0051] Passive conformation stage: After the actuator approaches the surface, the toes automatically conform to the irregular surface under the drive of the flexible joint to achieve local posture adjustment;

[0052] Preload application phase: The control rope and the main pull rope are used to pull the toes together and actively apply preload to ensure that the attachment is in full contact with the surface;

[0053] Negative pressure adsorption stage: The air pump is turned on, and the vacuum suction cup forms negative pressure to generate normal adsorption force. At the same time, pre-pressure strengthens the adhesion between the micro-nano dry adhesive layer and the surface, improving the adhesion stability;

[0054] Self-locking and holding stage: The worm gear motor is powered off and self-locked after tightening, maintaining the grip without continuous energy consumption, and the attachment process is stable and reliable;

[0055] Detachment and reset phase: The control system releases the air pressure and relaxes the rope tension at the same time. Under the action of the reset spring, the toes automatically rebound and open, completing the detachment.

[0056] The actuator achieves three-dimensional posture adjustment through "flexible joints + rope differential drive"; forms a composite adhesion mechanism through "vacuum adsorption + dry adhesion material", with strong adaptability and strong adhesion; and uses a worm gear structure to achieve low-power self-locking, with good dynamic stability and engineering controllability, and is suitable for human-computer interaction, robot surface operations and intelligent adhesion systems in a variety of complex environments.

[0057] It should be noted that, in this document, relational terms such as first and second, etc., are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprises," "comprising," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that includes a list of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such process, method, article, or apparatus.

[0058] The embodiments described above are merely descriptions of preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Without departing from the spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by persons skilled in the art should fall within the scope of protection defined by the claims of the present invention.

Claims

1. A bird claw actuator with a bending and twisting combined joint, comprising a sole (2), characterized in that: A plurality of toes (1) are hingedly connected to the sole (2), and each toe (1) comprises a connecting toe segment (1-1), two attached toe segments (1-2) and a hook toe segment (1-3). The middle parts of the connecting toe segment (1-1), the two attached toe segments (1-2) and the hook toe segment (1-3) are sequentially connected via a flexible joint (1-4). The upper surfaces of the connecting toe segment (1-1), the two attached toe segments (1-2) and the hook toe segment (1-3) are sequentially connected via a return spring (1-5). Pins (1-6) are installed inside the connecting toe segment (1-1), the two attached toe segments (1-2) and the hook toe segment (1-3).

2. The bird claw-like actuator with a bending-torsion combined joint according to claim 1, characterized in that: It also includes a main pull rope (1-7), one end of which is fixedly connected to the pin (1-6) at the hook toe joint (1-3), the middle part of the main pull rope (1-7) is wound and connected to the remaining pins (1-6), and the other end of the main pull rope (1-7) is connected to the control rope (1-8) through a ring structure.

3. The bird claw-like actuator with a bending-torsion combined joint according to claim 2, characterized in that: Two main pull ropes (1-7) are arranged, and the two main pull ropes (1-7) are respectively located at two ends of the pin (1-6).

4. The bird claw-like actuator with a bending-torsion combined joint according to claim 1, characterized in that: The attachment toe segment (1-2) comprises a bionic flexible attachment actuator (1-2-1), a toe segment body (1-2-2) and a trachea (1-2-3); the bionic flexible attachment actuator (1-2-1) and the toe segment body (1-2-2) are connected via a pin limiter; the bionic flexible attachment actuator (1-2-1) is connected to one end of the trachea (1-2-3); and the other end of the trachea (1-2-3) is connected to an external air source.

5. The bird claw-like actuator with a bending-torsion combined joint according to claim 4, characterized in that: The bionic flexible attachment actuator (1-2-1) comprises a vacuum adsorption layer (1-2-1-1) and a dry adhesion layer (1-2-1-2), wherein the vacuum adsorption layer (1-2-1-1) and the dry adhesion layer (1-2-1-2) are connected via a rigid connection hardware; The vacuum adsorption layer (1-2-1-1) is bonded to the attachment body (1-2-1-3).

6. The bird claw-like actuator with a bending-torsion combined joint according to claim 5, characterized in that: The vacuum adsorption layer (1-2-1-1) adopts an industrial vacuum suction cup, and the dry adhesion layer (1-2-1-2) imitates a gecko bristle array.

7. The bird claw-like actuator with a bending-torsion combined joint according to claim 1, characterized in that: The flexible joints (1-4) are integrally cast using a gradient hardness PDMS material.

8. The bird claw-like actuator with a bending-torsion combined joint according to claim 1, characterized in that: The return spring (1-5) is a shape memory alloy coil spring.

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