Bird-imitating multi-degree-of-freedom folding and unfolding wing device based on Bennett mechanism derivative space 8R mechanism

Abstract

The invention discloses a bird-imitating multi-degree-of-freedom folding and unfolding wing device based on a Bennett mechanism derivative space 8R mechanism, belongs to the technical field of folding and unfolding wing design, and aims to solve the problems that wing design of current fixed-wing and flapping-wing aircrafts is generally low in degree of freedom, and high-flexibility deformable wings of birds are insufficient in reduction degree. The mechanism comprises a humerus connecting rod combination body, an ulna connecting rod combination body, a radius connecting rod combination body, a wrist and metacarpal bone connecting rod combination body and a folding and unfolding driving unit, and the humerus connecting rod combination body, the ulna connecting rod combination body, the radius connecting rod combination body and the wrist and metacarpal bone connecting rod combination body jointly form a space 8R mechanism. The folding and unfolding driving unit is installed on the space 8R mechanism and drives the space 8R mechanism to conduct folding and unfolding actions, a wrist rotating steering engine is installed on the ulna connecting rod combination body, and the wrist rotating steering engine drives the wrist and metacarpal bone connecting rod combination body to rotate so as to drive the space 8R mechanism to conduct wrist rotating actions. The bird-imitating fixed wing and flapping wing structure is mainly used on an aircraft.

Description

Technical Field

[0001] This invention belongs to the field of folding wing design technology, specifically relating to a bird-like multi-degree-of-freedom folding wing device based on a Bennett mechanism-derived spatial 8R mechanism. Background Technology

[0002] Bird wings are a high-performance and efficient aerodynamic structure, endowing birds with the ability to fly at high speeds, with high maneuverability, and with low flight energy consumption. Therefore, they have attracted the attention of aerodynamic research and aircraft design engineering, and are used as design references for various fixed-wing and flapping-wing aircraft. Although the body structure of birds varies significantly due to their living environment and diet, especially in wing structure where there are considerable differences in skeletal size, feather shape, and length, they still share many structural similarities, particularly in the equivalent mechanism configuration of the skeleton. The spatial distribution of their kinematic pairs is basically consistent with their overall degrees of freedom. Basic movements they can perform include planar folding and spreading, forward and backward sweeping around the shoulder joint, and wrist joint twisting caused by the crossing of the radius and ulna. Theoretical analysis of their aerodynamic efficiency shows that birds adjust wing area through wing folding and spreading, adjust wing sweep angle and flapping direction through forward and backward sweeping, and change the angle of attack of the hand-wing portion through wrist joint twisting, thus achieving the needs of increasing lift and reducing drag during flight, adapting to complex flow environments, and performing complex maneuvers. Therefore, this multi-degree-of-freedom folding wing mechanism is very beneficial for enriching the mission functions of aircraft and improving their performance.

[0003] Large fixed-wing aircraft have relatively ample internal space in their wings and fuselage, allowing for the installation of complex flow control structures such as leading and trailing edge flaps, ailerons, and variable sweep angles, thus expanding the aircraft's adaptability to flow fields. However, smaller fixed-wing aircraft often lack the space for complex onboard devices and typically only have one or two pairs of trailing edge ailerons for roll control. Some innovative fixed-wing aircraft designs incorporate wing surface torsion mechanisms based on single hinges or other cascaded mechanisms. Due to the limited number of load-bearing points, the load is concentrated on one or a few hinges, potentially leading to insufficient reliability and reduced ability to withstand extreme conditions. This problem is more pronounced in flapping-wing aircraft. The high vibration and large alternating loads of flapping wings often result in insufficient reliability when introducing multi-degree-of-freedom designs. Furthermore, to avoid excessive flapping wing inertia, it is difficult to install additional mechanisms at the distal wing tip, meaning that most flapping-wing aircraft lack torsional freedom. Most mainstream flapping-wing aircraft currently use a single-segment wing configuration with no degrees of freedom or a two-segment wing configuration with only one bending degree of freedom. This results in insufficient reproduction of the actual flight movements of birds, leaving considerable potential for optimization. Summary of the Invention

[0004] In order to solve the problem that the wing designs of current fixed-wing and flapping-wing aircraft generally have low degrees of freedom and insufficient reproduction of the highly flexible deformable wings of birds, this invention provides a bird-inspired multi-degree-of-freedom flapping wing device based on the Bennett mechanism-derived spatial 8R mechanism.

[0005] A bird-inspired multi-degree-of-freedom folding wing device based on a Bennett mechanism-derived spatial 8R mechanism is disclosed. The folding wing device includes a humeral link assembly, an ulnar link assembly, a radius link assembly, a carpal metacarpal link assembly, and a folding drive unit. The humeral link assembly, ulnar link assembly, radius link assembly, and carpal metacarpal link assembly together form a spatial 8R mechanism. Four revolute joints in the spatial 8R mechanism are located at the connection points of two adjacent link assemblies. The rotation axis of the revolute joint between two adjacent link assemblies is perpendicular to the axis of the link assembly. The other four revolute joints in the spatial 8R mechanism are each located in a link assembly. The rotation axis of the revolute joint in the link assembly is collinear with the axis of the link assembly. The folding drive unit is mounted on the spatial 8R mechanism and drives the spatial 8R mechanism to perform folding and unfolding actions. A wrist rotation servo is mounted on the ulnar link assembly. The wrist rotation servo drives the carpal metacarpal link assembly to rotate, thereby driving the spatial 8R mechanism to perform wrist rotation actions.

[0006] Furthermore, one end of the humeral link assembly is hinged to one end of the ulnar link assembly to form a first revolute joint, the other end of the ulnar link assembly is hinged to the middle of the carpal metacarpal link assembly to form a second revolute joint, the radial link assembly is disposed on one side of the ulnar link assembly, one end of the radial link assembly is hinged to one end of the humeral link assembly to form a third revolute joint, and the other end of the radial link assembly is hinged to one end of the carpal metacarpal link assembly to form a fourth revolute joint;

[0007] Furthermore, the humeral link assembly is an integral structure, with a cross shaft in its middle that can rotate freely around its axis, and one end of the radial link assembly is hinged to the humeral link assembly through the cross shaft;

[0008] Furthermore, the ulnar link assembly includes a proximal end base and an output shaft. The wrist servo is installed in the proximal end base, and the wrist servo housing is fixedly connected to the proximal end base. The output shaft of the wrist servo extends through the proximal end base to the side of the proximal end base away from the fuselage, and is connected to one end of the output shaft through a coupling. One end of the humeral link assembly is hinged to the end of the proximal end base away from the fuselage, and the other end of the output shaft is hinged to the middle of the carpal metacarpal link assembly.

[0009] Furthermore, the radial link assembly includes a superior radial link and a inferior radial link. One end of the superior radial link is hinged to the humeral link assembly via a cross shaft. The other end of the superior radial link is inserted into one end of the inferior radial link and rotatably connected to the inferior radial link via a bearing. The other end of the inferior radial link is hinged to one end of the carpal metacarpal link assembly.

[0010] Furthermore, the carpal and metacarpal link assembly includes a radial articulated link and an ulnar articulated link. One end of the radial articulated link is hinged to the other end of the radial articulated link. The other end of the radial articulated link is inserted into one end of the ulnar articulated link and is rotatably connected to the ulnar articulated link through a bearing. The other end of the ulnar link assembly is hinged to the middle of the ulnar articulated link.

[0011] Furthermore, the folding drive unit includes a folding main drive link and a folding push rod. One end of the folding main drive link is hinged to the middle of the humeral link assembly, and the other end of the folding main drive link is connected to the drive source. One end of the folding push rod is hinged to the middle of the folding main drive link, and the other end of the folding push rod is hinged to the end of the proximal base near the body.

[0012] Furthermore, the distance between the ulnar link assembly and the main folding drive link on the humeral link assembly is consistent with the length of the corresponding part on the folding push rod;

[0013] Furthermore, the distance between the humeral link assembly and the folding push rod on the ulnar link assembly is consistent with the length of the corresponding part on the folding main drive link;

[0014] Furthermore, the corresponding parts on the main drive link and the corresponding parts on the push rod, together with the ulnar link assembly and the humeral link assembly, form a parallelogram mechanism.

[0015] The beneficial effects of this application compared to the prior art are:

[0016] 1. This application discloses a bird-inspired multi-degree-of-freedom folding wing device based on a Bennett mechanism-derived spatial 8R mechanism. It accurately replicates the mechanics and motion mechanisms of bird wing skeletons, achieving independent folding and wrist rotation with dual degrees of freedom through an innovative spatial 8R mechanism design. This effectively solves the technical pain points of existing bird-inspired aircraft, such as low wing surface degrees of freedom, poor flow field adaptability, insufficient mechanism reliability, and difficulty in deployment in small and medium-sized aircraft. It achieves significant technological breakthroughs in aerodynamic performance, mechanism operation, engineering applications, and cost control.

[0017] 2. The folding wing device provided in this application completely replicates the folding and wrist joint twisting motions of birds in nature. It allows for precise adjustment of the wing surface area through folding motions and changes in the angle of attack of the wing portion through wrist twisting motions, achieving wing shape control capabilities consistent with birds. It can flexibly perform lift-increasing and drag-reducing maneuvers under different flight conditions, adapting to complex flow environments, significantly improving the aerodynamic efficiency of the aircraft, and enabling high-maneuverability flight in multiple modes such as high-speed cruise, low-altitude maneuvering, and sharp climbs. Simultaneously, it effectively reduces flight energy consumption, meeting the flight performance requirements of medium and large bird-inspired fixed-wing and flapping-wing aircraft. Furthermore, folding and wrist twisting motions can be performed independently or simultaneously. During flight, the aircraft can adjust the wing surface state in real time according to changes in the flow field and maneuvering requirements, without any motion interference limitations. This expands the aircraft's adaptability to complex flight environments and solves the problem of narrow flow field adaptability caused by fixed or single-degree-of-freedom adjustment of traditional aircraft wing structures.

[0018] 3. The folding wing device provided in this application adopts a parallel mechanism design. Compared with the traditional series-type wing surface torsion mechanism, the load can be evenly distributed through multiple connecting rod assemblies and multiple kinematic pairs, avoiding the problem of excessive local stress caused by the load being concentrated on a single or a few hinges. The mechanism has high overall rigidity and strong load-bearing capacity, which can effectively withstand the complex working conditions of high vibration and large alternating loads during the flight of the flapping wing aircraft, and significantly improve the fatigue resistance and operational reliability of the wing structure. The four connecting rod assemblies of the humerus, ulna, radius, and carpal metacarpal bones in the wing form a closed-loop mechanism through hinges and revolute pairs, and each kinematic pair is connected by standardized components such as bearings and pins, resulting in high structural stability. During the repeated actions of folding and twisting the wrist, it is not prone to loosening or deformation, solving the technical problem of insufficient reliability of existing multi-degree-of-freedom wing surface designs in flapping wing aircraft.

[0019] 4. All core components of the folding wing device provided in this application adopt standardized designs. The linkage assemblies of the humerus, ulna, etc., are conventional mechanical structural parts. The folding drive system, wrist servo, bearings, pins, etc., are all general industrial components. This avoids complex non-standard parts processing and high-precision special kinematic pair design, significantly reducing the manufacturing difficulty and effectively controlling production costs. Furthermore, the connection methods of each component are simple, and the folding and wrist drive systems are independent, facilitating troubleshooting and component replacement, and reducing daily maintenance difficulty. Additionally, the kinematic pairs of the mechanism are all conventional revolute joints and hinges, simplifying lubrication and protection operations, further reducing the aircraft's later maintenance costs and facilitating the engineering promotion and mass application of this device. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the structure of the multi-degree-of-freedom folding wing device described in this application;

[0021] Figure 2This is an exploded view of the multi-degree-of-freedom folding wing device described in this application;

[0022] Figure 3 This is a schematic diagram of the multi-degree-of-freedom folding wing device described in this application;

[0023] Figure 4 This is a schematic diagram of the torsional process of the wrist joint of the biological forelimb corresponding to the multi-degree-of-freedom folding wing device described in this application;

[0024] Figure 5 This is a schematic diagram of the folding and unfolding action of the multi-degree-of-freedom folding and unfolding wing device described in this application;

[0025] Figure 6 This is a schematic diagram of the wrist rotation action of the multi-degree-of-freedom folding wing device described in this application;

[0026] Figure 7 This is a schematic diagram of a derivative mechanism of the space 8R mechanism in the multi-degree-of-freedom folding wing device described in this application;

[0027] In the diagram: 1. Humerus link assembly, 2. Ulnar link assembly, 3. Radius link assembly, 4. Carpal metacarpal link assembly, 5. Folding main drive link, 6. Folding push rod, and 7. Wrist servo. Detailed Implementation

[0028] Specific implementation method one: Combining Figure 1 and Figure 7 This embodiment describes a bird-inspired multi-degree-of-freedom folding and unfolding wing device based on a Bennett mechanism-derived spatial 8R mechanism. The folding and unfolding wing device includes a humeral link assembly 1, an ulnar link assembly 2, a radial link assembly 3, a carpal and metacarpal link assembly 4, and a folding and unfolding drive unit. The humeral link assembly 1, ulnar link assembly 2, radial link assembly 3, and carpal and metacarpal link assembly 4 together form a spatial 8R mechanism. The four revolute joints in the spatial 8R mechanism are located at the connection points of adjacent link assemblies. The rotation axis of the rotating joint located between two adjacent linkage assemblies is perpendicular to the axis of the linkage assembly. The other four rotating joints in the space 8R mechanism are located in a linkage assembly. The rotation axis of the rotating joint located in the linkage assembly is collinear with the axis of the linkage assembly. The folding and unfolding drive unit is installed on the space 8R mechanism and drives the space 8R mechanism to perform folding and unfolding actions. The ulnar linkage assembly 2 is equipped with a wrist rotation servo motor 7. The wrist rotation servo motor 7 drives the carpal metacarpal linkage assembly 4 to rotate, thereby driving the space 8R mechanism to perform wrist rotation actions.

[0029] One end of the humeral link assembly 1 is hinged to one end of the ulnar link assembly 2 to form a first revolute joint. The other end of the ulnar link assembly 2 is hinged to the middle of the carpal and metacarpal link assembly 4 to form a second revolute joint. The radial link assembly 3 is located on one side of the ulnar link assembly 2. One end of the radial link assembly 3 is hinged to one end of the humeral link assembly 1 to form a third revolute joint. The other end of the radial link assembly 3 is hinged to one end of the carpal and metacarpal link assembly 4 to form a fourth revolute joint.

[0030] In this embodiment, the spatial 8R mechanism is the core of the multi-degree-of-freedom folding wing device. It is equivalent in principle to the forelimb of birds. The forelimbs of most organisms are constructed through two revolute joints and two ball joints formed between the humerus, ulna, radius, and carpal metacarpal bones, creating a spatial mechanism. Wrist joint rotation can be achieved by utilizing the intersection of the ulna and radius. According to kinematic principles, each ball joint can be decomposed into three revolute joints whose axes intersect at a single point, thus forming an equivalent 8R mechanism for the biological forelimb. This 8R mechanism has two degrees of freedom: a folding motion requiring only the hinges between four linkages, and a spatial torsional motion requiring all eight revolute joints. The folding motion corresponds to the folding function of the folding wing mechanism itself, while the torsional motion corresponds to the wrist rotation function. This mechanism has properties similar to the Bennett mechanism and can be considered a derivative of the Bennett mechanism. It is studied and modeled using some of the principles and analytical methods of the Bennett mechanism. In the Bennett mechanism, the ratio of the sine values ​​of the torsion angles of each link is equal to the ratio of their lengths. This property ensures that the mechanism remains under load even when the torsion angle changes. Based on this, precise control of the wrist rotation angle can be achieved. Under a certain link assembly length ratio, for each angle output by the wrist rotation servo 7, the torsion angle of the end carpal metacarpal link assembly 4 is uniquely determined. Based on this, precise control of the wrist rotation angle can be achieved. Under a preset link assembly length ratio, the output angle of the wrist rotation servo 7 and the torsion angle of the end carpal metacarpal link assembly 4 have a unique correspondence, which greatly improves the accuracy of wing attitude control and enables precise control of aircraft flight maneuvers.

[0031] Refer to the instruction manual Figure 4 As shown, in practical applications, the revolute joints of the spatial 8R mechanism provided in this embodiment can be recombined into ball joints or other forms. The revolute joints on each link assembly can move arbitrarily along the axis of the link. When they coincide with the hinge at the end of a link assembly, they are equivalent to a Hooke's hinge; when two adjacent revolute joints coincide with a hinge, they are equivalent to a ball joint. These derived mechanisms are completely equivalent to the original mechanism in engineering. In practical engineering applications, the derived mechanism whose performance best meets the design requirements can be selected as needed.

[0032] The multi-degree-of-freedom folding wing device or derivative mechanism provided in this embodiment performs folding and twisting movements independently without interfering with each other, allowing for a large reach and flexible movement. Due to the parallel mechanism, the entire mechanism has high rigidity, strong load-bearing capacity, relatively distributed load, and higher reliability. The mechanism is simple, occupies little space, and does not involve complex non-standard parts or high kinematic pairs, making it easy and cost-effective to implement. It is easy to deploy on small and medium-sized aircraft and suitable for widespread use.

[0033] Specific Implementation Method Two: Combining Figures 1 to 7 This embodiment is a further limitation of the first specific embodiment. The humeral link assembly 1 is an integral structure, with a cross shaft in its middle that can rotate freely around its axis. One end of the radial link assembly 3 is hinged to the humeral link assembly 1 through the cross shaft.

[0034] The ulnar link assembly 2 includes a proximal end base and an output shaft. The wrist servo 7 is installed in the proximal end base, and the housing of the wrist servo 7 is fixedly connected to the proximal end base. The output shaft of the wrist servo 7 passes through the proximal end base and extends to the side of the proximal end base away from the fuselage. It is connected to one end of the output shaft through a coupling. One end of the humeral link assembly 1 is hinged to the end of the proximal end base away from the fuselage. The other end of the output shaft is hinged to the middle of the carpal metacarpal link assembly 4.

[0035] The radial link assembly 3 includes a superior radial link and a inferior radial link. One end of the superior radial link is hinged to the humeral link assembly 1 via a cross shaft. The other end of the superior radial link is inserted into one end of the inferior radial link and is rotatably connected to the inferior radial link via a bearing. The other end of the inferior radial link is hinged to one end of the carpal metacarpal link assembly 4.

[0036] The carpal and metacarpal link assembly 4 includes a radial hinge link and an ulnar hinge link. One end of the radial hinge link is hinged to the other end of the radial link, and the other end of the radial hinge link is inserted into one end of the ulnar hinge link and rotatably connected to the ulnar hinge link via a bearing. The other end of the ulnar link assembly 2 is hinged to the middle of the ulnar hinge link. Other components and connection methods are the same as in specific embodiment one.

[0037] In this embodiment, the two ends of the cross shaft in the humeral link assembly 1 are rotatably connected to the main body of the humeral link assembly 1 through bearings, thereby forming a rotating pair on the assembly. The ulnar link assembly 2, the radius link assembly 3, and the carpal and metacarpal link assembly 4 are all segmented structures, connected together by a rotating pair around their axis in the middle. The two segments in each assembly can rotate arbitrarily around their own axis. Each link assembly has a mounting hole at each end, which is connected by bearings and pins to form a hinge structure.

[0038] In this embodiment, a multi-degree-of-freedom folding wing device is formed by four linkage assemblies. Based on this, the folding drive system and the wrist rudder mechanism are combined to form a folding wing as a whole. There are no redundant transmission components and complex structures, the overall space occupies little space, and each component is arranged along the linkage axis and the wing surface direction, which fits the wing structure characteristics of bird-inspired aircraft. It can be successfully deployed on medium and large bird-inspired fixed-wing and flapping-wing aircraft with a total weight of not less than 200g and a wingspan of more than 800mm, solving the problem that small and medium-sized aircraft cannot arrange complex wing surface adjustment structures due to space limitations.

[0039] In this embodiment, the linkage assembly of the humerus, ulna, etc., consists of conventional mechanical structural components. The folding and unfolding drive system, wrist rotation servo, bearings, pins, etc., are all general industrial parts. It does not involve complex non-standard parts processing or high-precision special kinematic pair design, which greatly reduces the processing and manufacturing difficulty of the product and effectively controls the production and manufacturing costs. On this basis, the connection method of each component is simple, the folding and unfolding and wrist rotation drive systems are independent of each other, the fault diagnosis and component replacement are convenient, and the daily maintenance difficulty is low. At the same time, the kinematic pairs of the mechanism are all conventional revolute joints and hinges, and the lubrication and protection operations are simple, which further reduces the later maintenance costs of the aircraft and is conducive to the engineering promotion and mass application of this device.

[0040] Specific implementation method three: Combining Figures 1 to 7 This embodiment is a further limitation of the first specific embodiment. The folding and unfolding drive unit includes a folding and unfolding main drive link 5 and a folding and unfolding push rod 6. One end of the folding and unfolding main drive link 5 is hinged to the middle of the humeral link assembly 1, and the other end of the folding and unfolding main drive link 5 is connected to the drive source. One end of the folding and unfolding push rod 6 is hinged to the middle of the folding and unfolding main drive link 5, and the other end of the folding and unfolding push rod 6 is hinged to the end of the proximal base near the body.

[0041] The distance between the humeral link assembly 1 and the folding push rod 6 on the ulnar link assembly 2 is consistent with the length of the corresponding part on the folding main drive link 5. The distance between the ulnar link assembly 2 and the folding main drive link 5 on the humeral link assembly 1 is consistent with the length of the corresponding part on the folding push rod 6. The corresponding parts on the folding main drive link 5, the corresponding parts on the folding push rod 6, together with the ulnar link assembly 2 and the humeral link assembly 1, form a parallelogram mechanism. Other components and connection methods are the same as in Specific Implementation Method 1.

[0042] In this embodiment, the folding and unfolding drive unit is the core transmission and drive structure for the folding and unfolding motion in the multi-degree-of-freedom folding and unfolding wing device. This design is not a simple reuse of the conventional parallelogram mechanism, but a customized design that combines the working conditions of bird-like wing folding and unfolding motion with the motion characteristics of the spatial 8R mechanism. It has multiple significant technical advantages in terms of power transmission, motion control, mechanism stability, and bionic adaptability.

[0043] Firstly, the core mechanical characteristics of the parallelogram mechanism are that opposite sides are parallel and equal, and each hinge point performs planar motion at the same speed and in the same direction during the rotation of the connecting rod. The main drive connecting rod 5 for folding and unfolding serves as the power input component. Its rotational power can be transmitted synchronously and at the same speed to the humeral connecting rod assembly 1 and the ulnar connecting rod assembly 2 through this structure, so that the included angle of the axes of the two core skeletal connecting rods changes linearly and smoothly. This avoids the problem of local jamming, stuttering, or asynchronous movement on the wing surface during folding and unfolding, and achieves a smooth connection between wing folding and unfolding actions, matching the natural folding and unfolding movement rhythm of bird wings. At the same time, the parallelogram structure realizes power transmission through four hinge points. Compared with the single-point force transmission design of single push rod and single connecting rod, the load can be evenly distributed among each hinge point and connecting rod segment, avoiding local stress concentration during power transmission, effectively reducing the wear rate of bearings and pins at the hinges, while ensuring the power transmission efficiency of the folding and unfolding drive system, reducing power loss, and adapting to the power output characteristics of the miniaturized drive system of bird-inspired aircraft.

[0044] Secondly, the parallelogram mechanism is a closed, rigid structure that provides strict geometric constraints on the rotational trajectories of the humeral link assembly 1 and the ulnar link assembly 2. This ensures that the two links maintain a predetermined spatial relative position during the folding and unfolding process, guaranteeing that the wing's unfolding angle and folding curvature closely match the movement trajectory of birds' wings in nature. This avoids wing surface distortion caused by link misalignment, ensuring the biomimetic accuracy of the folding and unfolding motion. Consequently, it ensures stable aerodynamic performance of the wing surface at different folding and unfolding angles. Based on the geometric characteristics of the parallelogram mechanism, the rotation angle of the main folding and unfolding drive link 5 and the angle between them and the axes of the humeral and ulnar link assemblies change along a unique linear curve. The corresponding relationship allows for precise control of the wing's folding degree by adjusting the rotation angle of the main folding drive linkage, eliminating the need for additional angle compensation or correction mechanisms. This significantly reduces the complexity of the folding motion control algorithm and enables precise, quantitative control of the wing's folding angle. Furthermore, compared to the open series drive structure, the parallelogram mechanism offers higher overall stiffness and superior torsional and bending resistance, effectively withstanding the high vibrations and large alternating aerodynamic loads generated during bird-inspired flight. This prevents the folding drive structure from loosening, deforming, or failing in vibration environments, greatly improving the structural stability and reliability of the folding wing device under complex flight conditions.

[0045] Finally, the parallelogram structure, as an independent driving unit for the folding motion, only affects the relative angle adjustment between the humeral link assembly 1 and the ulnar link assembly 2. The locking and unlocking of its motion configuration only affects the folding degree of freedom and does not interfere with the rotational joints of the skeletal link assembly required for wrist rotation. When the wrist rotation servo 7 drives the wrist rotation movement, the parallelogram structure maintains its position. By locking the included angle of the axes of the humeral and ulnar links, it provides a stable structural foundation for the wrist rotation movement of the spatial 8R mechanism. From a structural design perspective, it achieves complete decoupling of the two degrees of freedom—folding and wrist rotation—which aligns with the core design requirement of independent dual-action motion in this invention.

[0046] The parallelogram-shaped drive structure, consisting of the humeral link assembly 1, the ulnar link assembly 2, the folding and unfolding main drive link 5, and the folding and unfolding push rod 6, not only achieves efficient, precise, and stable drive of the folding and unfolding motion of the folding and unfolding wing, but also ensures the independence of the folding and unfolding and wrist rotation movements from a structural perspective. At the same time, it takes into account the stability, spatial adaptability, and engineering practicality of the mechanism, becoming one of the core technical highlights of the bird-inspired multi-degree-of-freedom folding and unfolding wing device of this application compared with traditional folding and unfolding wing mechanisms.

[0047] The present invention has been disclosed above with preferred embodiments, but it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed structure and technical content to create equivalent embodiments without departing from the scope of the present invention. However, any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

[0048] Working principle:

[0049] The working principle of this application is to replicate the mechanism of folding and extending of a bird's forelimb and the twisting of its wrist joint. It forms a spatial 8R mechanism through two revolute joints and two ball joints between the humerus, ulna, radius, and carpal metacarpal bones, achieving wrist joint twisting through the crossing of the ulna and radius. The humeral link assembly 1, ulnar link assembly 2, radial link assembly 3, and carpal metacarpal link assembly 4 together constitute this spatial 8-bar mechanism, which is equivalent to the mechanism of a bird's forelimb in principle. This 8R mechanism has two motion states: a folding motion requiring only the hinges between four link assemblies, and a spatial twisting motion requiring all eight revolute joints. The folding motion corresponds to the folding function of the folding wing mechanism itself, while the twisting motion corresponds to the wrist rotation function of the folding wing mechanism. These two motion states can be performed independently or simultaneously. The following example illustrates the working process of the folding wing mechanism by showing the two motions performed independently.

[0050] When the folding wing performs the folding action, the wrist servo 7 does not rotate, thereby locking all the rotating pairs on the humeral link assembly 1, the ulnar link assembly 2, the radial link assembly 3, and the carpal and metacarpal link assembly 4, forming a planar or spatial four-bar linkage mechanism. The folding main drive link 5 swings, which drives the angle between the axes of the humeral link assembly 1 and the ulnar link assembly 2 to change via the folding push rod 6, thus forming the folding and unfolding motion of the wing.

[0051] When the folding wing performs a wrist rotation action, the folding main drive link 5 and the folding push rod 6 remain stationary, thus locking the angle between the axes of the humeral link assembly 1 and the ulnar link assembly 2. The wrist rotation servo 7 drives the revolute joint on the humeral link assembly 1 to rotate, and the angles of the revolute joints on the other three skeletal link assemblies change accordingly. The four-bar linkage formed by the humeral link assembly 1, the ulnar link assembly 2, the radial link assembly 3, and the carpal metacarpal link assembly 4 rotates around its diagonal. The ulnar link assembly 2 and the radial link assembly 3 intersect each other, forming a skeletal movement similar to that of a bird rotating its wing wrist joint.

[0052] The folding and wrist-rotating actions can be performed independently and repeatedly. When the folding main drive link 5 and the folding push rod 6 are in any non-overlapping and locked position, the wrist-rotating servo 7 can rotate freely. When the wrist-rotating servo 7 rotates to any angle and is locked, the folding main drive link 5 and the folding push rod 6 can also push the mechanism to fold freely. The two movements can also be performed simultaneously without affecting each other.

Claims

1. A bird-inspired multi-degree-of-freedom folding wing device based on a Bennett mechanism-derived spatial 8R mechanism, characterized in that: The folding and unfolding device includes a humeral link assembly (1), an ulnar link assembly (2), a radial link assembly (3), a carpal metacarpal link assembly (4), and a folding and unfolding drive unit. The humeral link assembly (1), ulnar link assembly (2), radial link assembly (3), and carpal metacarpal link assembly (4) together form a spatial 8R mechanism. The four revolute joints in the spatial 8R mechanism are located at the connection of two adjacent link assemblies. The axis of rotation of the revolute joint between two adjacent link assemblies is perpendicular to the axis of the link assembly. The other four revolute joints in the spatial 8R mechanism are located in a link assembly. The axis of rotation of the revolute joint in the link assembly is collinear with the axis of the link assembly. The folding and unfolding drive unit is installed on the spatial 8R mechanism and drives the spatial 8R mechanism to perform folding and unfolding actions. A wrist rotation servo (7) is installed on the ulnar link assembly (2). The wrist rotation servo (7) drives the carpal metacarpal link assembly (4) to rotate, thereby driving the spatial 8R mechanism to perform wrist rotation actions.

2. The bird-like multi-degree-of-freedom folding wing device based on a Bennett mechanism-derived spatial 8R mechanism according to claim 1, characterized in that: One end of the humeral link assembly (1) is hinged to one end of the ulnar link assembly (2) to form a first revolute joint. The other end of the ulnar link assembly (2) is hinged to the middle of the carpal metacarpal link assembly (4) to form a second revolute joint. The radial link assembly (3) is located on one side of the ulnar link assembly (2). One end of the radial link assembly (3) is hinged to one end of the humeral link assembly (1) to form a third revolute joint. The other end of the radial link assembly (3) is hinged to one end of the carpal metacarpal link assembly (4) to form a fourth revolute joint.

3. The bird-like multi-degree-of-freedom folding wing device based on a Bennett mechanism-derived spatial 8R mechanism according to claim 2, characterized in that: The humeral link assembly (1) is an integral structure with a cross shaft in its middle that can rotate freely around its axis. One end of the radial link assembly (3) is hinged to the humeral link assembly (1) through the cross shaft.

4. The bird-like multi-degree-of-freedom folding wing device based on the Bennett mechanism-derived spatial 8R mechanism according to claim 1, characterized in that: The ulnar link assembly (2) includes a proximal end base and an output shaft. The wrist servo (7) is installed in the proximal end base, and the housing of the wrist servo (7) is fixedly connected to the proximal end base. The output shaft of the wrist servo (7) extends through the proximal end base to the side of the proximal end base away from the fuselage, and is connected to one end of the output shaft through a coupling. One end of the humeral link assembly (1) is hinged to the end of the proximal end base away from the fuselage, and the other end of the output shaft is hinged to the middle of the carpal metacarpal link assembly (4).

5. A bird-like multi-degree-of-freedom folding wing device based on a Bennett mechanism-derived spatial 8R mechanism according to claim 4, characterized in that: The radial link assembly (3) includes a superior radial link and a inferior radial link. One end of the superior radial link is hinged to the humeral link assembly (1) via a cross shaft. The other end of the superior radial link is inserted into one end of the inferior radial link and is rotatably connected to the inferior radial link via a bearing. The other end of the inferior radial link is hinged to one end of the carpal and metacarpal link assembly (4).

6. A bird-like multi-degree-of-freedom folding wing device based on a Bennett mechanism-derived spatial 8R mechanism according to claim 5, characterized in that: The wrist and metacarpal link assembly (4) includes a radial hinge link and an ulnar hinge link. One end of the radial hinge link is hinged to the other end of the radial upper link. The other end of the radial hinge link is inserted into one end of the ulnar hinge link and is rotatably connected to the ulnar hinge link through a bearing. The other end of the ulnar link assembly (2) is hinged to the middle of the ulnar hinge link.

7. A bird-like multi-degree-of-freedom folding wing device based on a Bennett mechanism-derived spatial 8R mechanism according to claim 6, characterized in that: The folding drive unit includes a folding main drive link (5) and a folding push rod (6). One end of the folding main drive link (5) is hinged to the middle of the humeral link assembly (1), and the other end of the folding main drive link (5) is connected to the drive source. One end of the folding push rod (6) is hinged to the middle of the folding main drive link (5), and the other end of the folding push rod (6) is hinged to the end of the proximal base near the fuselage.

8. A bird-like multi-degree-of-freedom folding wing device based on a Bennett mechanism-derived spatial 8R mechanism according to claim 7, characterized in that: The distance between the humeral link assembly (1) and the folding push rod (6) on the ulnar link assembly (2) is consistent with the length of the corresponding part on the folding main drive link (5).

9. A bird-like multi-degree-of-freedom folding wing device based on a Bennett mechanism-derived spatial 8R mechanism according to claim 8, characterized in that: The distance between the ulnar link assembly (2) and the folding main drive link (5) on the humeral link assembly (1) is consistent with the length of the corresponding part on the folding push rod (6).

10. A bird-like multi-degree-of-freedom folding wing device based on a Bennett mechanism-derived spatial 8R mechanism according to claim 9, characterized in that: The corresponding parts of the folding main drive link (5), the corresponding parts of the folding push rod (6), together with the ulnar link assembly (2) and the humeral link assembly (1), form a parallelogram mechanism.

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