Grippable mechanism suitable for bionic micro flapping-wing air vehicle

Abstract

The invention provides a grabbable mechanism suitable for a bionic micro flapping-wing air vehicle. The grabbable mechanism is composed of a bistable strip-shaped spring, a grabbing arm and a connecting rod mechanism. The appearance design and function of the mechanism are inspired by the grabbing process of the bird claw, the bistable strip-shaped spring is adopted as a core deformation component for the grabbing mechanism to generate opening and closing movement, and the function of grabbing a target object under specific conditions and the function of automatically unfolding and separating from the target object can be achieved. In addition, the mechanism is simple in component composition, efficient in force transmission and light in weight, has good bionic characteristics, can adapt to various micro aircrafts and application scenes, and is excellent in comprehensive performance.

Description

Technical Field

[0001] The invention relates to the field of micro flapping-wing aircraft and provides a grasping mechanism suitable for bionic micro flapping-wing aircraft. Background Art

[0002] Hummingbird-like micro flapping-wing aircraft can achieve hovering and maneuvering flight, and has the characteristics of strong maneuverability, and has broad application prospects in the military and civilian fields. Although such aircraft have excellent flight performance, they currently do not have the functions of climbing and grasping like birds in nature, which makes them unable to dock freely with the help of obstacles in the surrounding environment, which is not conducive to adjusting the take-off posture before repeated take-off, and also limits their application in scenes with many obstacles such as forests.

[0003] At present, the industrial field has relatively mature grasping mechanism designs, such as "A UAV perching bionic claw device (application publication number: CN116923758A)", "A knee-triggered spring cable bionic claw collaborative grasping method (authorization announcement number: CN117021063B)", etc. These designs are exquisite but the structure is relatively complex and the weight is relatively large. Since micro-UAVs have light weight and limited net lift, the mechanism design needs to have both bionic and lightweight characteristics, and minimize the number and weight of connectors. This patent provides a method that imitates the appearance, function and application scenarios of bird claws in nature to design a grasping mechanism based on a bionic micro flapping-wing aircraft. The mechanism uses a bistable strip spring structure as the core component of the grasping. It has a simple structure and light weight, which helps to improve the concealment and flexibility of the aircraft. Summary of the invention

[0004] The present invention is aimed at the field of bionic grasping mechanism of micro flapping-wing aircraft, and proposes to add a bionic grasping mechanism part to the existing micro flapping-wing aircraft, inspired by bird claws in nature, so as to realize the function of the aircraft to grasp or cling to the target object, improve the site adaptability and concealment of the aircraft, and effectively expand the application scenarios of the aircraft.

[0005] The grabbing mechanism suitable for a bionic micro flapping-wing aircraft is fixedly connected to the bottom of the aircraft and comprises a bistable belt spring, a grabbing arm and a connecting rod mechanism.

[0006] The bistable strip spring is a thin-walled structure with two stable states: a flat unfolded state and a bent and coiled state. Both of these stable states correspond to the minimum values of strain energy, and under appropriate loading conditions, it can cross the energy barrier to achieve the switching between the two stable states. The initial state of the bistable strip spring is the flat unfolded state, in which the convex side is on the upper side, the cross-sectional shape is circular arc-shaped, and the normal direction at any position on the curved surface passes through the center of the cross-sectional circle. When an upward and appropriately sized load is applied to the concave side, the bistable strip spring bends towards the concave side and finally reaches the bent and coiled state. At this time, the cross-section changes from circular arc-shaped to straight-line-shaped, and the original straight axis becomes a bent arc facing downward. The size of the energy barrier between the two stable states of the bistable strip spring is related to the size and material of the bistable strip spring. The selected material is a composite material, which is composed of a polymer material and a reinforcing material.

[0007] The grasping arm is a three-dimensional structure. In the device of the present invention, there are two identical and symmetrically placed grasping arms, which are respectively connected to the two end faces of the bistable strip spring. The connection between the grasping arm and the bistable strip spring is a groove similar to the shape of an arch. This groove is composed of four surfaces: the lower bottom surface that conforms to the arc-shaped cross-sectional shape of the bistable strip spring in the flat unfolded state, the upper bottom surface that conforms to the straight-line-shaped cross-sectional shape of the bistable strip spring in the bent and coiled state, and the left and right side surfaces that adapt to the asymptotic line shape of the cross-section of the bistable strip spring during the switching between the two states. The closest distance between the upper and lower bottom surfaces of the groove is equal to the thickness of the bistable strip spring, ensuring that there is no gap in the connection between this part and the bistable strip spring, and the grasping arm and the bistable strip spring are connected by bonding at this part. An earpiece structure is designed on the upper side of the groove of the grasping arm and is connected to the rod of the connection mechanism. A through hole is designed on the earpiece. The lower side of the grasping arm refers to the geometric shape of a bird's claw and is designed with a curved claw arm for easy grasping.

[0008] The link mechanism is a three-dimensional structure, including a pair of long rods, a pair of short rods, and a fixed seat. There is a through hole at each end of the long rod and the short rod for forming kinematic pairs with the slot holes of other components. The fixed seat is directly fixed to the aircraft. There is a round hole on the upper side of the fixed seat, which is hinged to the through hole at one end of the long rod, and there is a chute on the lower side, which is matched with the through hole at one end of the short rod. The round holes at the other ends of the long rod and the short rod are hinged to the earpieces of the grasping arm.

[0009] The described grasping mechanism applicable to a bionic micro flapping-wing aircraft is characterized in that the bistable characteristic of the bistable strip spring comes from the antisymmetric ply of the composite material; the "polymer material" constituting the bistable strip spring is epoxy resin, styrene, styrene-butadiene, trans-polyisoprene, cyanate ester, polyurethane, polynorbornene, polyimide, bismaleimide, polyamide, polyphenylene sulfide, polyaryletherketone, polyvinyl alcohol, etc., and the "reinforcing material" is carbon fiber, glass fiber, Kevlar fiber, boron fiber, plant fiber or the fabric of the above fibers, etc.

[0010] The described grasping mechanism applicable to a bionic micro flapping-wing aircraft is characterized in that the through hole of the short rod of the link mechanism can be regarded as a slider, which cooperates with the chute of the fixed seat to form a moving pair, and drives the long rod, the short rod and the grasping arm to move; when the slider is at the uppermost position of the chute, it corresponds to the straight unfolded state of the bistable strip spring and the open state of the grasping arm; when the slider is at the lowermost position of the chute, it corresponds to the bent and retracted state of the bistable strip spring and the closed state of the grasping arm.

[0011] The described grasping mechanism applicable to a bionic micro flapping-wing aircraft is characterized in that under specific loading conditions, the bistable strip spring can be transformed from a straight state to a bent and retracted state to grasp a target object within a certain mass range; during the process of the aircraft approaching the grasped target object, the bistable strip spring is in a straight unfolded state; when the bistable strip spring contacts the target object, the strip spring receives a reaction load from the target object; if under the action of the gravitational potential energy and falling kinetic energy of the aircraft, the reaction load can reach a certain threshold, the bistable strip spring can convert part of the work done by the external load into strain energy and transform from a straight unfolded state to a bent and retracted state. At this time, the grasping arm is transformed from an open state to a closed state to achieve object grasping.

[0012] The described grasping mechanism applicable to a bionic micro flapping-wing aircraft is characterized in that when the target object can be regarded as a large-mass and stationary climbing object, the bistable strip spring can be transformed from a bent and retracted state to a straight unfolded state, so as to disengage from the target object and achieve re-flight; when the aircraft is about to take off after the climbing is over, the aircraft generates a vertical upward lift force, which has a tendency to open the grasping arm and transform the bistable strip spring to a straight state. Under the reasonable design of the bistable strip spring, part of the work done by the lift force can enable the bistable strip spring to cross the energy barrier and transform to a straight state, while achieving disengagement from the target object, automatically completing the steady-state switching, which is beneficial to the reproduction of the grasping function.

[0013] The preparation and installation method of the described grasping mechanism applicable to a bionic micro flapping-wing aircraft is as follows:

[0014] Step 1: Determine the composite components for fabricating the bistable strip spring, i.e., the reinforcing material and the polymer material, and determine the geometric dimensions of the bistable strip spring.

[0015] Step 2: Determine the curing and forming method of the composite material.

[0016] Step 3: Determine the key dimensions of the long rod, short rod, and fixed seat in the linkage mechanism to ensure that the linkage mechanism does not interfere with the bistable strip spring.

[0017] Step 4: Pass both ends of the bistable strip spring through the grooves of the grasping arm respectively, and bond the middle part near the grooves of the bistable strip spring and the grasping arm with an adhesive.

[0018] Step 5: Hinge the through holes at one end of the long rod and the short rod with the lugs of the grasping arm respectively, hinge the through hole at the other end of the long rod with the upper through hole of the fixed seat, and mate the through hole at the other end of the short rod with the lower sliding groove of the fixed seat. Finally, fix the fixed seat on the aircraft.

[0019] The advantages of the present invention are as follows:

[0020] 1. Based on the bionics principle, a set of bionic motion mechanisms capable of realizing the grasping function is designed, laying a foundation for the development of the aircraft.

[0021] 2. Creatively use the bistable strip spring as the core component for the mechanism to generate the unfolding and closing motions, and the motion relationship of the whole mechanism is simple.

[0022] 3. Through modular design, each part of the device can be decomposed into simple independent units, which is convenient for disassembly, assembly, and maintenance, saving maintenance costs. Brief Description of the Drawings

[0023] Figure 1 is the overall schematic diagram of the unfolding state of a grasping mechanism applicable to a bionic micro flapping-wing aircraft according to the present invention;

[0024] Figure 2 is the schematic diagram of the bistable strip spring of a grasping mechanism applicable to a bionic micro flapping-wing aircraft according to the present invention;

[0025] Figure 3 is the schematic diagram of the grasping arm of a grasping mechanism applicable to a bionic micro flapping-wing aircraft according to the present invention;

[0026] Figure 4 is the schematic diagram of the linkage mechanism of a grasping mechanism applicable to a bionic micro flapping-wing aircraft according to the present invention;

[0027] Figure 5 is the schematic diagram of the grasping state of a grasping mechanism applicable to a bionic micro flapping-wing aircraft according to the present invention;

[0028] In the figure:

[0029] 1 - Bistable strip spring, 2 - Gripping arm, 3 - Linkage mechanism

[0030] 301 - Long rod, 302 - Short rod, 303 - Fixed seat Specific implementation manner

[0031] The following will describe in detail the specific implementation method of the present invention in conjunction with the accompanying drawings.

[0032] The grippable mechanism applicable to a bionic micro flapping wing aircraft is fixedly connected to the bottom of the aircraft and includes a bistable strip spring 1, a gripping arm 2, and a linkage mechanism 3.

[0033] The bistable strip spring 1 is a thin-walled structure with two stable states: a flat unfolded state and a bent and coiled state. Both of these stable states correspond to the minimum values of strain energy, and under appropriate loading conditions, it can cross the energy barrier to achieve the switching between the two stable states: The initial state of the bistable strip spring 1 is the unfolded flat state. In this state, the convex side is on the upper side, the cross-sectional shape is circular arc-shaped, and the normal direction at any position on the curved surface passes through the center of the circular arc of the cross-section; when an upward and appropriately sized load is applied to the concave side, the bistable strip spring 1 bends towards the concave side and finally reaches the bent and coiled state. At this time, the cross-section changes from circular arc-shaped to straight-line-shaped, and the original straight axis becomes a bent arc-shaped facing downward; the size of the energy barrier between the two stable states of the bistable strip spring 1 is related to the size and material of the bistable strip spring. The selected material is a composite material, which is composed of a polymer material and a reinforcing material;

[0034] The gripping arm 2 is a three-dimensional structure. In the device of the present invention, there are two identical and symmetrically placed gripping arms 2, which are respectively connected to the two end faces of the bistable strip spring 1. The connection between the gripping arm 2 and the bistable strip spring 1 is a groove similar to the shape of an arch. This groove is composed of four faces in total: the lower bottom surface that fits the arc-shaped cross-sectional shape of the bistable strip spring 1 in the flat unfolded state, the upper bottom surface that fits the straight-line-shaped cross-sectional shape of the bistable strip spring 1 in the bent and coiled state, and the left and right side faces that adapt to the asymptotic shape of the cross-section of the bistable strip spring during the switching between the two states. The closest distance between the upper and lower bottom surfaces of the groove is equal to the thickness of the bistable strip spring 1, ensuring that there is no gap in the connection between this part and the bistable strip spring 1. At this part, the gripping arm 2 and the bistable strip spring 1 are connected by an adhesive bonding method; An earpiece structure is designed on the upper side of the groove of the gripping arm 2 and is connected to the rod of the connecting mechanism. Through holes are designed on the earpiece; The lower side of the gripping arm 2 refers to the geometric shape of a bird's claw and is designed with a curved claw arm for easy gripping;

[0035] The link mechanism 3 is a three-dimensional structure, including a pair of long rods 301, a pair of short rods 302 and a fixed seat 303; both ends of the long rod 301 and the short rod 302 have a through hole for forming a kinematic pair with the slot holes of other components; the fixed seat 303 is directly fixed to the aircraft, and there is a round hole on the upper side of the fixed seat 303 hinged to the through hole at one end of the long rod 301, and there is a sliding groove on the lower side cooperating with the through hole at one end of the short rod 302. The round holes at the other ends of the long rod 301 and the short rod 302 are hinged to the lugs of the grasping arm 2.

[0036] The described grasping mechanism applicable to a bionic micro flapping-wing aircraft is characterized in that the bistable characteristic of the bistable strip spring 1 comes from the anti-symmetric ply of the composite material; the "polymer material" constituting the bistable strip spring 1 is epoxy resin, styrene, styrene-butadiene, trans-polyisoprene, cyanate ester, polyurethane, polynorbornene, polyimide, bismaleimide, polyamide, polyphenylene sulfide, polyaryletherketone, polyvinyl alcohol, etc., and the "reinforcing material" is carbon fiber, glass fiber, Kevlar fiber, boron fiber, plant fiber or the fabric of the above fibers, etc.

[0037] The described grasping mechanism applicable to a bionic micro flapping-wing aircraft is characterized in that the through hole of the short rod 302 of the link mechanism 3 can be regarded as a slider, which cooperates with the sliding groove of the fixed seat 303 to form a translating pair, driving the long rod 301, the short rod 302 and the grasping arm 2 to move; when the slider is at the uppermost position of the sliding groove, it corresponds to the straight unfolded state of the bistable strip spring 1 and the open state of the grasping arm 2; when the slider is at the lowermost position of the sliding groove, it corresponds to the bent and retracted state of the bistable strip spring 1 and the closed state of the grasping arm 2.

[0038] The described grasping mechanism applicable to a bionic micro flapping-wing aircraft is characterized in that under specific loading conditions, the bistable strip spring 1 can be transformed from a straight state to a bent and retracted state to grasp a target object within a certain mass range; during the process of the aircraft approaching the grasped target object, the bistable strip spring 1 is in a straight unfolded state; when the bistable strip spring 1 contacts the target object, the strip spring receives a reaction load from the target object; if under the action of the gravitational potential energy and falling kinetic energy of the aircraft, the reaction load can reach a certain threshold, the bistable strip spring 1 can convert part of the work done by the external load into strain energy and be transformed from a straight unfolded state to a bent and retracted state. At this time, the grasping arm 2 is transformed from an open state to a closed state to achieve object grasping.

[0039] The described graspable mechanism applicable to a bionic micro flapping-wing aircraft is characterized in that when the target object can be regarded as a large-mass and stationary climbing object, the bistable ribbon spring 1 can be transformed from a bent and retracted state to a straight and unfolded state, so as to disengage from the target object and achieve re-flight; when the aircraft finishes climbing and is about to take off, the aircraft generates a vertical upward lift force, which has a tendency to open the grasping arm 2 and transform the bistable ribbon spring 1 into a straight state. With reasonable design of the bistable ribbon spring 1, part of the work done by the lift force can enable the bistable ribbon spring 1 to cross the energy barrier and transform into a straight state, while achieving disengagement from the target object, automatically completing the steady-state switching, which is beneficial to the reproduction of the grasping function.

[0040] The preparation and installation method of the described graspable mechanism applicable to a bionic micro flapping-wing aircraft is as follows:

[0041] Step 1: Determine the composite material components for preparing the bistable ribbon spring 1, namely the reinforcing material and the polymer material, and determine the geometric dimensions of the bistable ribbon spring.

[0042] Step 2: Determine the curing and forming method of the composite material.

[0043] Step 3: Determine the key dimensions of the long rod 301, the short rod 302 and the fixed seat 303 in the linkage mechanism 3 to ensure that the linkage mechanism 3 does not interfere with the bistable ribbon spring 1.

[0044] Step 4: Pass the two ends of the bistable ribbon spring 1 through the grooves of the grasping arm 2 respectively, and bond the middle part close to the grooves of the bistable ribbon spring 1 and the grasping arm 2 with an adhesive.

[0045] Step 5: Hinge the through holes at one end of the long rod 301 and the short rod 302 with the lugs of the grasping arm 2 respectively, hinge the through hole at the other end of the long rod 301 with the upper through hole of the fixed seat 303, and fit the through hole at the other end of the short rod 302 with the lower chute of the fixed seat 303. Finally, fix the fixed seat 303 on the aircraft.

Claims

1. A graspable mechanism applicable to a bionic micro flapping-wing aircraft, fixedly connected to the bottom of the aircraft, comprising a bistable strip spring, a grasping arm, and a linkage mechanism, characterized in that: The bistable strip spring is a thin-walled structure with two stable states of straight expansion and curved retraction. Both of these stable states correspond to the minimum values of strain energy, and under appropriate loading conditions, it can cross the energy barrier to achieve the switching between the two stable states: The initial state of the bistable strip spring is the straight-expanded state. In this state, the convex side is located above, the cross-sectional shape is circular arc-shaped, and the normal direction at any position on the curved surface passes through the center of the cross-sectional arc; when an upward and appropriately sized load is applied to the concave side, the bistable strip spring bends towards the concave side and finally reaches the curved retracted state. At this time, the cross-section changes from circular arc-shaped to straight-line-shaped, and the original straight axis becomes a curved arc facing downward. The material selected for the bistable strip spring is a composite material, composed of a polymer material and a reinforcing material. The grasping arm is a three-dimensional structure, connected to the end face of the bistable strip spring. The connection between the grasping arm and the bistable strip spring is a groove similar to the shape of an arch. This groove is composed of four surfaces in total: the lower bottom surface that fits the arc-shaped cross-sectional shape of the bistable strip spring in the straight-expanded state, the upper bottom surface that fits the straight-line-shaped cross-sectional shape of the bistable strip spring in the curved retracted state, and the left and right side surfaces that adapt to the asymptotic line shape of the cross-section of the bistable strip spring during the switching between the two states. The closest distance between the upper and lower bottom surfaces of the groove is equal to the thickness of the bistable strip spring, ensuring that there is no gap in the connection between this part and the bistable strip spring; an earpiece structure is designed on the upper side of the groove of the grasping arm and is connected to the rod of the connection mechanism. Through holes are designed on the earpiece; the lower side of the grasping arm refers to the geometric shape of a bird's claw and is designed with a curved claw arm for easy grasping. The linkage mechanism is a three-dimensional structure, including a pair of long rods, a pair of short rods, and a fixed seat; through holes are provided at both ends of the long rods and short rods for forming kinematic pairs with the slot holes of other components; the fixed seat is directly fixedly connected to the aircraft. There is a circular hole on the upper side of the fixed seat for hinging with the through hole at one end of the long rod, and a chute on the lower side for cooperating with the through hole at one end of the short rod. The circular holes at the other ends of the long rods and short rods are hinged to the earpieces of the grasping arm.

2. The graspable mechanism applicable to a bionic micro flapping-wing aircraft according to claim 1, characterized in that, The bistable characteristics of the bistable strip spring come from the anti-symmetric ply of the composite material; the "polymer material" constituting the bistable strip spring is epoxy resin, styrene, styrene-butadiene, trans-polyisoprene, cyanate ester, polyurethane, polynorbornene, polyimide, bismaleimide, polyamide, polyphenylene sulfide, polyaryletherketone, polyvinyl alcohol, etc., and the "reinforcing material" is carbon fiber, glass fiber, Kevlar fiber, boron fiber, plant fiber, or the above fiber fabrics, etc.

3. The graspable mechanism applicable to the bionic micro flapping wing aircraft according to claim 1, characterized in that, The through hole of the short rod of the linkage mechanism can be regarded as a slider, which cooperates with the chute of the fixed seat to form a moving pair, and drives the long rod, the short rod and the grasping arm to move; when the slider is at the uppermost position of the chute, it corresponds to the straight unfolded state of the bistable ribbon spring and the open state of the grasping arm; when the slider is at the lowermost position of the chute, it corresponds to the bent and retracted state of the bistable ribbon spring and the closed state of the grasping arm.

4. The gripper mechanism applicable to a bionic micro flapping-wing aircraft according to claims 1-3, characterized in that, Under specific loading conditions, the bistable ribbon spring can be transformed from the straight state to the bent and retracted state to achieve the grasping of target objects within a certain mass range; During the process of the aircraft approaching the grasped target object, the bistable ribbon spring is in the straight unfolded state; when the bistable ribbon spring contacts the target object, the ribbon spring receives a reaction load from the target object; If under the action of the gravitational potential energy and falling kinetic energy of the aircraft, the reaction load can reach a certain threshold, the bistable ribbon spring can convert part of the work done by the external load into strain energy and be transformed from the straight unfolded state to the bent and retracted state. At this time, the grasping arm is transformed from the open state to the closed state to achieve object grasping.

5. A graspable mechanism applicable to a bionic micro flapping-wing aircraft according to any one of claims 1-3, characterized in that, When the target object can be regarded as a large-mass and stationary clinging object, the bistable ribbon spring can be transformed from the bent and retracted state to the straight unfolded state, so as to break away from the target object and achieve reflight; when the aircraft is about to take off after the clinging is completed, the aircraft generates a vertical upward lift force, which has a tendency to open the grasping arm and transform the bistable ribbon spring to the straight state. Under the reasonable design of the bistable ribbon spring, part of the work done by the lift force can enable the bistable ribbon spring to cross the energy barrier and transform to the straight state, while achieving the separation from the target object, automatically completing the steady-state switching.

6. A graspable mechanism applicable to a bionic micro flapping-wing aircraft according to any one of claims 1-3, and its preparation and installation method are as follows: Step 1: Determine the composite material components for preparing the bistable ribbon spring, namely the reinforcing material and the polymer material, and determine the geometric dimensions of the bistable ribbon spring; Step 2: Determine the curing and forming method of the composite material; Step 3: Determine the key dimensions of the long rod, short rod and fixed seat in the linkage mechanism to ensure that the linkage mechanism does not interfere with the bistable ribbon spring; Step 4: Pass the two ends of the prepared bistable ribbon spring through the grooves of the grasping arm respectively, and bond the middle part close to the bistable ribbon spring and the grooves of the grasping arm with an adhesive; Step 5: Hinge the through holes at one end of the long rod and the short rod with the lugs of the grasping arm respectively, hinge the through hole at the other end of the long rod with the upper through hole of the fixed seat, and match the through hole at the other end of the short rod with the lower chute of the fixed seat. Finally, fix the fixed seat on the aircraft.

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