Experimental device for testing mechanical properties of bionic opposite-flapping flapping wings

Abstract

The invention discloses an experimental device for testing mechanical properties of bionic opposite-shooting flapping wings, which relates to the technical field of mechanical testing devices and comprises a truss, a force measuring system, a driving mechanism, a water tank, a high-speed camera and a laser light source. By controlling the flapping frequency of the flapping wings and the proportion of the downward flapping time, asymmetric opposite flapping flapping of the flapping wings is achieved; the structural parameters of the flapping wing are further changed by changing the length of the wing panel. The wing panel is transversely arranged in a test environment, so that the wing panel rigidity assumption that the aspect ratio is greater than 5 can be fully met; the number and the position relation of the main shafts are changed, so that the number and the distance of constraint points of flapping wing panels are changed, the flapping wings are controlled to meet rigid body conditions, the requirements for testing hydrodynamic characteristics such as thrust, lateral force and torque and flow fields under different Reynolds numbers can be met, and the relation between hydrodynamic force and flapping wing structure parameters and motion parameters can be explored. According to the invention, an experimental basis and a design reference can be provided for the research of a bionic flapping wing propelled underwater vehicle in the next step.

Description

Technical Field

[0001] The invention relates to the technical field of mechanical testing devices, in particular to an experimental device for testing the mechanical performance of bionic flapping wings. Background Art

[0002] Since the late 1990s, Micro Air Vehicles (MAV) have attracted more and more interest in the fields of engineering and science, especially MAVs with insect-scale scale can provide breakthrough solutions for many industries. Since MAV flies at extremely low Reynolds numbers, its aerodynamic characteristics, such as lift-to-drag ratio and stall speed, are very important research directions compared to large aircraft. The structure of the flying wing has a decisive effect on the aerodynamic characteristics of MAV. In the prior art, MAV winglets can be divided into three types: fixed wing, rotating wing and flapping wing. Among them, fixed wing and rotating wing are less difficult to develop, but the lift-to-drag ratio is difficult to improve at low Reynolds numbers and the maneuverability is poor. Flapping wing MAV imitates the flight mode of birds or insects, has high flight efficiency and flexible maneuverability, and is an ideal choice for the future development and upgrading of MAV.

[0003] Flying animals flap their wings to create lift and thrust, and have significant maneuverability and rapid acceleration and deceleration characteristics. Based on bionics, people study double-wing propulsion, explore the fluid mechanics of MAV, and use unsteady aerodynamics to design future micro-aircraft. In order to study the flapping process, propulsion, rapid flipping of stroke and other factors, people have developed a bionic flapping mechanics experimental device, which includes a truss, a force measuring system, a drive mechanism and a water tank. The drive mechanism drives the flapping wing model to open and close in an "umbrella-shaped" manner, so as to intuitively measure the thrust changes of the flapping wing model. This experimental device can better measure the thrust changes generated during the flapping process, but its common feature is that the wing blades are arranged vertically below the force measuring mechanism and the drive mechanism along the span direction. The problems include the following:

[0004] 1. It is difficult to use high-speed cameras or other devices to record the changes in the flow field in the water tank during flapping. Even if an underwater high-speed camera is used, the servo or other driving mechanism above will be obviously blocked.

[0005] 2. The experimental device in the prior art has very limited space to change the wing constraint point to increase the wing rigidity. In practice, in order to meet the rigid body assumption, special requirements need to be made on the wing material, and the weight must be light.

[0006] 3. After the wing is arranged vertically, if the span length of the wing is extended, especially for the flapping wing model with an aspect ratio greater than 5, the rigid body assumption of the wing is difficult to meet. Summary of the invention

[0007] In order to solve the above-mentioned problems existing in the fluid mechanics experimental device in the prior art, meet the research requirements of monitoring the changes in the fluid field while testing the thrust of flapping wings and the rigid body assumption of the wing, and further improve the accuracy of the experimental results, the present invention provides an experimental device for testing the mechanical properties of bionic flapping wings.

[0008] To achieve the above object, the present invention provides the following solutions:

[0009] The invention provides an experimental device for testing the mechanical properties of bionic flapping wings, comprising a truss, a force measuring system, a driving mechanism, a water tank, a high-speed camera and a laser light source; the top of the water tank is open, and the truss is arranged above the water tank; the high-speed camera is arranged on the left or right side of the water tank, and the laser light source is arranged on the front or rear side of the water tank; the force measuring system is arranged on the top of the truss, and the driving mechanism is arranged on the bottom of the force measuring system; the driving mechanism is used for connecting with a flapping wing and driving the flapping wing to move.

[0010] Optionally, the force measuring system includes a force sensor, a firmware bracket, a firmware and a main shaft; the top of the force sensor is connected to the top bottom surface of the truss, the firmware bracket is provided at the bottom of the force sensor, the firmware is provided at the bottom of the firmware bracket, and the bottom of the firmware is connected to the upper end of the main shaft.

[0011] Optionally, two ends of the firmware are respectively connected to the upper end of one of the main shafts, and the two main shafts are connected via a support connecting beam.

[0012] Optionally, the driving mechanism includes a servo, a servo connecting rod, a slider, a slider sleeve, a flapping-wing connecting end, a flapping-wing connecting rod, a first connecting fulcrum, a flapping-wing connecting device, a first endpoint, a second endpoint, and a second connecting fulcrum; the servo is arranged on a firmware in the force measuring system; the servo connecting rod of the servo is connected to the slider, the slider sleeve is connected to the slider, and the slider sleeve is slidably sleeved on the main shaft in the force measuring system; a first connecting fulcrum is respectively arranged on both sides of the slider sleeve; the flapping-wing connecting end is arranged at the lower end of the main shaft in the force measuring system, and a second connecting fulcrum is respectively arranged on both sides of the flapping-wing connecting end; one end of the flapping-wing connecting rod is rotatably connected to the first connecting fulcrum, the other end of the flapping-wing connecting rod is rotatably connected to one end of the flapping-wing connecting device, and the other end of the flapping-wing connecting device is rotatably connected to the second connecting fulcrum; the flapping-wing connecting device is used to clamp the flapping wings.

[0013] Optionally, the servo connecting rod includes a first servo connecting rod and a second servo connecting rod; one end of the first servo connecting rod is connected to the output shaft of the servo, the other end of the first servo connecting rod is rotatably connected to one end of the second servo connecting rod, and the other end of the second servo connecting rod is rotatably connected to the slider.

[0014] Optionally, the flapping-wing connecting device includes a first hinge and a second hinge; the middle part of the first hinge is connected to one end of the first hinge connecting rod, and the second hinge connecting rod is provided at one end of the second hinge; the middle part of the first hinge and one end of the second hinge are respectively located on both sides of the flapping wing, and are connected to the flapping wing by screws, the other end of the first hinge connecting rod is rotatably connected to the flapping-wing connecting rod, and the second hinge connecting rod is rotatably connected to the second connecting fulcrum of the flapping-wing connecting end.

[0015] Optionally, tracer particles are provided in the water tank.

[0016] Optionally, the tracer particles are hollow glass microspheres with a diameter of 5-20 μm and a density of 1.05×10 3 g / cm 3 .

[0017] Optionally, the laser light source is a continuous laser, which generates a laser sheet light with a thickness of 1 mm through an optical lens group, and illuminates the flow field from the side wall of the water tank to capture the flow field.

[0018] Compared with the prior art, the present invention has achieved the following technical effects:

[0019] The present invention is an experimental device for testing the mechanical properties of bionic flapping wings. By controlling the flapping frequency and the proportion of the down-flapping time, the asymmetric flapping of the flapping wings is realized. By changing the length of the wing, the flapping wing structural parameters (aspect ratio) are further changed. The flapping wing of the present invention is arranged horizontally in the test environment, which can fully meet the wing rigidity assumption that the aspect ratio is greater than 5. By changing the number and position relationship of the main axes, the number and distance of the constraint points of the flapping wing are changed, and the flapping wings are controlled to meet the rigid body conditions, which can further meet the hydrodynamic characteristics and flow field requirements of thrust, lateral force, torque, etc. under different Reynolds numbers within the test range of 103 and 104, so as to explore the relationship between hydrodynamic force and flapping wing structural parameters and motion parameters. The present invention also provides a solution for exploring the propulsion efficiency problem of bionic flapping wings. It can simultaneously realize direct force measurement and fluid display, and adopt a high-speed camera, an acquisition card and a synchronous control device to realize a particle image velocimetry (PIV) device to measure the details and structure of the unsteady flow around the flapping wing under typical working conditions. Combined with flow field analysis methods such as vortex dynamics and proper orthogonal decomposition (POD), the efficiency of flapping wing propulsion is explored with the maximum net thrust as an indicator. This can provide an experimental basis and design reference for the next step of research on bionic flapping wing propulsion underwater vehicles. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0021] Figure 1 It is a three-dimensional schematic diagram of the present invention;

[0022] Figure 2 It is a schematic diagram of the application of two main axis double constraint points of the present invention;

[0023] Figure 3 It is a schematic diagram of the structure of two main axis double constraint points of the present invention;

[0024] Figure 4 It is a front view of the driving mechanism and the force measuring mechanism of the present invention;

[0025] Figure 5 It is a side view of the driving mechanism and the force measuring mechanism of the present invention;

[0026] Figure 6 is a partial enlarged view of the first flapping-wing connecting device and the second flapping-wing connecting device of the present invention;

[0027] Reference numerals: 1, truss; 2, force measurement system; 3, driving mechanism; 4, water tank; 5, first flapping wing; 6, second flapping wing; 7, high-speed camera; 8, laser light source; 9, support connecting beam;

[0028] 201, force sensor; 202, firmware bracket; 203, firmware; 204, spindle;

[0029] 301, servo; 302, servo connecting rod; 303, slider; 304, slider sleeve; 308, flapping wing connecting end; 309, first flapping wing connecting rod; 310, first flapping wing blade; 311, first connecting fulcrum; 312, first flapping wing connecting device; 313, first endpoint; 314, second endpoint; 315, second flapping wing connecting rod; 316, second flapping wing blade; 317, second flapping wing connecting device; 318, second connecting fulcrum;

[0030] 30201, first connecting rod of servo; 30202, second connecting rod of servo;

[0031] 31201, first hinge; 31203, first hinge connecting rod; 31204, second hinge connecting rod;

[0032] 31701, third hinge; 31702, fourth hinge; 31703, third hinge connecting rod; 31704, fourth hinge connecting rod. DETAILED DESCRIPTION

[0033] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0034] In order to intuitively describe the embodiments of the present invention, two coordinate systems are first defined: a ground coordinate system XYZ and a body coordinate system X'Y'Z' of a flapping wing. The X-axis of the ground coordinate system coincides with or is parallel to the flapping rotation axis of the flapping wing, and the Z-axis of the ground coordinate system is parallel to the principal axis of the present invention; the X'-axis of the body coordinate system is parallel to the X-axis of the ground coordinate system, and the Y'-axis of the body coordinate system is always in the YZ plane of the ground coordinate system or parallel to the YZ plane of the ground coordinate system. The X'-axis direction of the body coordinate system is the span direction of the flapping wing, and the Y'-axis direction of the body coordinate system is the chord direction of the flapping wing.

[0035] The purpose of the present invention is to provide an experimental device for testing the mechanical properties of bionic flapping wings, which meets the research requirements of monitoring the changes in the fluid field while testing the thrust of the flapping wings and the rigid body assumption of the wing, and further improves the accuracy of the experimental results. The present invention provides an experimental device for testing the mechanical properties of bionic flapping wings.

[0036] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0037] like Figures 1 to 6As shown, this embodiment provides an experimental device for testing the mechanical properties of bionic flapping wings, comprising a truss 1, a force measuring system 2, a driving mechanism 3, a first flapping wing 5 and a second flapping wing 6; the force measuring system comprises a force sensor 201, a fixture bracket 202, a fixture 203 and a main shaft 204; the truss 1 is fixedly mounted on the experimental table as a supporting skeleton of the entire experimental device; in a more general sense, the truss 1 can be mounted on any fixed supporting object in the laboratory. The force sensor 201 is connected to the truss 1 at one end and to the fixture bracket 202 at the other end, and the thrust generated by the flapping of the first flapping wing 5 and the second flapping wing 6 is measured by a direct force measurement method; the fixture bracket 202 is connected to the fixture 203, and is arranged on the upper side of the fixture 203, and is located between the force sensor 201 and the fixture 203, that is, the force sensor 201 is connected to the fixture 203 through the fixture bracket 202. The force sensor 201 should be understood in a broad sense, including hooks, springs, tension and pressure force sensors, and electronic data processing systems, etc. The connection with the object to be measured and the supporting mechanism is achieved through hooks, springs, etc., and the data input and output of the force sensor is achieved through the electronic data processing system. This is a conventional instrument in a general laboratory, and the present invention will not further describe the implementation method.

[0038] One end of the main shaft 204 is connected to the fixture 203 and is located at the lower side of the fixture 203; the other end of the main shaft 204 is provided with a flapping wing connection end 308 for movably connecting the first flapping wing 5 and the second flapping wing 6; the flapping wing connection end 308 includes two first connection fulcrums 311 and second connection fulcrums 318 symmetrically arranged with the center point of the flapping wing connection end 308 as the symmetry point, and the line connecting the first connection fulcrum 311 and the second connection fulcrum 318 is perpendicular to the main shaft 204. Those skilled in the art may understand the main shaft 204 together with the flapping wing connection end 308 as an inverted "T"-shaped structure, and the first connection fulcrum 311 and the second connection fulcrum 318 are symmetrically arranged at the two ends of the horizontal bar of the "T"-shaped structure. It is further understood that the line connecting the first connection fulcrum 311 and the second connection fulcrum 318 coincides with or is parallel to the XY plane. See the attached figure. Figure 1 , Attachment Figure 2 and attached Figure 4 When viewing the experimental device from the vertical direction, the top is the truss 1, followed by the force sensor 201, the fixture bracket 202, the fixture 203, the main shaft 204 and the flapping wing connection end 308.

[0039] See attached Figure 5The first flapping wing 5 includes a first flapping wing piece 310 and a first flapping wing connecting device 312, and the first flapping wing piece 310 and the first flapping wing connecting device 312 are fixedly connected; the second flapping wing 6 includes a second flapping wing piece 316 and a second flapping wing connecting device 317, and the second flapping wing piece 316 and the second flapping wing connecting device 317 are fixedly connected; the flapping wing connecting end 308 is movably connected to the first flapping wing connecting device 312 through a first connecting fulcrum 311; the span direction of the first flapping wing piece 310 is perpendicular to the main axis 204; the flapping wing connecting end 308 is movably connected to the second flapping wing connecting device 317 through a second connecting fulcrum 318, and the second flapping wing 6 and the first flapping wing 5 are symmetrically arranged on the flapping wing. The first flapping wing 5 and the second flapping wing 6 are symmetrically arranged at the two ends of the flapping wing connection end 308, the axis of symmetry is the main axis 204, and the center of symmetry is the center of the flapping wing connection end 308; and under the drive of the driving mechanism 3, the first flapping wing 5 can rotate with the first connection fulcrum 311 as the fulcrum and the axis parallel to the span direction of the first flapping wing 310 as the rotation axis, and the second flapping wing 6 can rotate with the second connection fulcrum 318 as the fulcrum and the axis parallel to the span direction of the second flapping wing 316 as the rotation axis, so as to realize the first flapping wing and the second flapping wing to beat and flap up and down. Further, the rotation of the first flapping wing 5 and the second flapping wing 6 is to flap up and down with the straight line parallel to the X-axis as the rotation axis. It is specially noted that the movable connection here, including the movable connection described in other parts of this specification, can be broadly understood as a universal connection, or narrowly understood as an axis connection or a pin connection, etc., unless otherwise specified, as long as the purpose of the present invention can be achieved, the present invention does not make any further limitations on this.

[0040] The main shaft 204 is arranged in the vertical direction and is parallel to the Z axis. Since the main shaft 204 is perpendicular to the span direction of the first flapping wing 310 and the second flapping wing 316, the first flapping wing 5 and the second flapping wing 6 are arranged horizontally along their span direction, that is, the first flapping wing 5 and the second flapping wing 6 are transversely installed on the flapping wing connecting end 308 on the main shaft 204 along their span direction. That is, the span direction of the first flapping wing 310 and the second flapping wing 316 is parallel to the X axis.

[0041] In order to ensure that the first flapping wing 5 and the second flapping wing 6 are subjected to balanced and symmetrical flapping driving forces, the main axis 204 is perpendicular to the span direction of the first flapping wing 5 and the second flapping wing 6; when the first flapping wing 5 and the second flapping wing 6 rotate in a vertical plane with the first connecting fulcrum 311 and the second connecting fulcrum 318 as fulcrums respectively, the chord direction of the first flapping wing 5 and the second flapping wing 6 is always in the YZ plane or parallel to the YZ plane.

[0042] The driving mechanism 3 includes a servo 301, a servo connecting rod 302, a slider 303, a first flapping-wing connecting rod 309 and a second flapping-wing connecting rod 315; the servo 301 is connected to the fixture 203; in order to make the experimental device simpler, the servo 301 is located on the fixture 203 and is located on the same side as the main shaft 204; however, even if the servo 301 and the main shaft 204 are not on the same side, the purpose of the present invention can be achieved, and the present invention does not limit this; the servo 301 is connected to the servo connecting rod 302, the servo connecting rod 302 is connected to the slider 303, the slider 303 includes a slider sleeve 304, the slider 303 is sleeved on the main shaft 204 through the slider sleeve 304, and the slider 303 can slide up and down along the main shaft 204. Preferably, the main shaft 204 is made of a material with a smooth surface to reduce the friction of the slider and further reduce the experimental error factor. The up and down sliding of the slider 303 is driven by the servo 301 through the servo connecting rod 302, so that the slider 303 can slide back and forth up and down along the main shaft 204; the slider 303 includes a first endpoint 313 and a second endpoint 314; the first endpoint 313 and the second endpoint 314 are on the outside of the slider sleeve 304, and are symmetrically arranged with the main shaft 204 as the symmetry axis, and are respectively used to flexibly connect the first flapping-wing connecting rod 309 and the second flapping-wing connecting rod 315.

[0043] When designing the experimental device, the main shaft 204 may be vertically connected to the fixture 203; the slider 303 may be in the shape of a straight line or a straight bar and vertically connected to the main shaft 204. Of course, other solutions may also be used to achieve the purpose of the present invention, and the present invention is not limited thereto.

[0044] One end of the first flapping-wing connecting rod 309 is movably connected to the first end point 313, and the first flapping-wing connecting rod 309 can rotate in a vertical plane with the first end point 313 as a fulcrum, that is, rotate in a plane parallel to the Z axis, so that the first flapping-wing connecting rod 309 can drive the first flapping wing 5 to rotate or flap up and down with the first connection fulcrum 311 as a fulcrum and an axis parallel to the extension direction of the first flapping-wing wing 310 as a rotation axis; the other end of the first flapping-wing connecting rod 309 is movably connected to the first flapping-wing connecting device 312, so that the first flapping-wing connecting rod 309 can drive the first flapping wing 5 to flap up and down along its rotation axis under the drive of the servo 301; One end of the second flapping-wing link 315 is movably connected to the second endpoint 314, and the second flapping-wing link 315 can rotate in a vertical plane with the second endpoint 314 as a fulcrum, that is, rotate in a plane parallel to the Z axis. The purpose is that the second flapping-wing link 315 can drive the second flapping wing 6 to rotate or flap up and down with the second connection fulcrum 318 as a fulcrum and the axis parallel to the extension direction of the second flapping wing 316 as the rotation axis; the other end of the second flapping-wing link 315 is movably connected to the second flapping-wing connecting device 317, so that the second flapping-wing link 315 can push the second flapping wing 6 to flap up and down along its rotation axis under the drive of the servo 301.

[0045] When in use, the servo 301 drives the slider 303 to reciprocate up and down along the main shaft 204 through the servo connecting rod 302, thereby driving the first flapping wing connecting rod 309 and the second flapping wing connecting rod 315 to reciprocate in a plane parallel to the Z axis respectively; the first flapping wing connecting rod 309 and the second flapping wing connecting rod 315 respectively drive the first flapping wing 5 and the second flapping wing 6 to perform periodic flapping up and down on the flapping wing connecting end 308. During the experiment, the speed, time and proportion of the flapping time of the flapping wing can be controlled by controlling the movement cycle of the servo, so as to realize the thrust parameters of the flapping wing in various asymmetric experimental designs. During the flapping process, the force sensor records and outputs the measurement data, and the servo outputs the driving data.

[0046] As a preferred embodiment, in order to further meet the rigidity assumption of the constraint points of the first flapping wing 5 and the second flapping wing 6 in the test, when designing this experimental device, the first flapping wing link 309, the second flapping wing link 315, the line between the first endpoint 313 and the second endpoint 314, the first connection fulcrum 311 and the second connection fulcrum 318 associated with or matched with the same main axis are all in the same vertical plane. Those skilled in the art can understand that the flapping wing constraint point is the force point that fixes the flapping wing and flaps up and down; if the number and position of the constraint points on each flapping wing change, the rigidity of the flapping wing will change slightly. For multiple constraint points, multiple main axes will be applied. For the case of multiple main axes, the first flapping wing link, the second flapping wing link, the line between the first endpoint and the second endpoint, the first connection fulcrum and the second connection fulcrum connected to different main axes will not all be in the same vertical plane.

[0047] Further, as a preferred embodiment of the steering gear connecting rod 302, see the attached Figure 4 and attached Figure 5 The servo connecting rod 302 includes a first servo connecting rod 30201 and a second servo connecting rod 30202; that is, the servo 301 is connected to the slider 303 through the first servo connecting rod 30201 and the second servo connecting rod 30202; one end of the first servo connecting rod 30201 is connected to the rotating shaft of the servo 301, and the servo 301 can drive the first servo connecting rod 30201 to rotate in a vertical plane with the servo 301 as the center, or to rotate with the rotating shaft of the servo 301 as the center; the other end of the first servo connecting rod 30201 is movably connected to one end of the second servo connecting rod 30202; the second servo connecting rod 30202 can make up and down reciprocating motion under the drive of the first servo connecting rod 30201; the other end of the second servo connecting rod 30202 is connected to the slider 303. The second connecting rod 30202 of the servo drives the slider 303 to slide reciprocatingly up and down along the main shaft 204 through the driving force output by the servo 301. It is particularly noted that the movable connection here can be broadly understood as a universal connection, or narrowly understood as an axis connection or a pin connection, etc., as long as the purpose of the present invention can be achieved, and the present invention does not make further limitations on this.

[0048] Further, as a preferred embodiment in which the flapping wings are connected to the main shaft and the flapping wing connecting rod respectively through the flapping wing connecting device, see the attached Figure 5 and attached Figure 6 , the first flapping-wing connecting device 312 includes a screw, a first hinge 31201 and a second hinge (not shown in the figure); the first flapping-wing wing piece 310 includes a screw hole; the first hinge 31201 includes a first hinge connecting rod 31203 and a screw hole, and one end of the first hinge connecting rod 31203 is fixedly connected to the first hinge 31201; the second hinge includes a second hinge connecting rod 31204 and a screw hole, and one end of the second hinge connecting rod 31204 is fixedly connected to the second hinge; the positions and apertures of the screw holes on the first flapping-wing piece, the screw holes on the first hinge, and the screw holes on the second hinge match; the first hinge 31201 and the second hinge are respectively located on the upper and lower sides of the first flapping-wing wing piece 310, and The first flapping wing 310 is fixed or closed by screw holes and screws; the end of the first hinge link 31203 away from the first flapping wing 310 is movably connected to the other end of the first flapping wing link 309, so as to achieve the purpose of movably connecting one end of the first flapping wing link 309 to the first endpoint 313 and movably connecting the other end of the first flapping wing link 309 to the first flapping wing connecting device 312; that is, the first flapping wing link 309 is movably connected to the end of the first hinge link 31203 away from the first flapping wing 310, so as to output power and drive the first flapping wing 310 to flap up and down with the first connection fulcrum 311 as the fulcrum and the axis parallel to the X-axis as the rotation axis. The movable connection here can be broadly understood as a universal connection, or narrowly understood as an axis connection or a pin connection, etc., as long as the present invention can be implemented, the present invention does not make further limitations on this. The end of the second hinge link 31204 away from the first flapping wing 310 connects the flapping wing connecting end 308 with the first flapping wing 5 through the first connecting fulcrum 311, ensuring that the first flapping wing 5 can flap vertically up and down with the first connecting fulcrum 311 as the fulcrum and the axis parallel to the extension direction of the first flapping wing 310 as the rotation axis; that is, under the drive of the first flapping wing link 309, the first flapping wing 310 can flap up and down with the first connecting fulcrum 311 as the fulcrum; similarly, the movable connection here can be broadly understood as a universal connection, or narrowly understood as an axis connection or a pin connection, etc., and the present invention does not make further limitations on this.

[0049] The connection method is exactly the same as that of the first flapping-wing connection device. The second flapping-wing connection device 317 includes a screw, a third hinge 31701 and a fourth hinge 31702; the second flapping-wing wing piece 316 includes a screw hole; the third hinge 31701 includes a third hinge connecting rod 31703 and a screw hole, and one end of the third hinge connecting rod 31703 is fixedly connected to the third hinge 31701; the fourth hinge 31702 includes a fourth hinge connecting rod 31704 and a screw hole, and one end of the fourth hinge connecting rod 31704 is fixedly connected to the fourth hinge 31702; the positions and apertures of the screw holes on the second flapping-wing piece, the screw holes on the third hinge and the screw holes on the fourth hinge match; the third hinge 31701 and the fourth hinge 31702 are respectively located at the second flapping-wing wing piece 316 The upper and lower sides are fixed or closed by screw holes and screws; the end of the third hinge link 31703 away from the second flapping wing 316 is movably connected to the other end of the second flapping wing link 315, so as to achieve the purpose of movably connecting one end of the second flapping wing link 315 to the second endpoint 314 and movably connecting the other end of the second flapping wing link 315 to the first flapping wing connecting device 317; the end of the fourth hinge link 31704 away from the second flapping wing 316 movably connects the flapping wing connecting end 308 with the second flapping wing 6 through the second connecting fulcrum 318; under the drive of the second flapping wing link 315, the second flapping wing 316 can flap up and down with the second connecting fulcrum 318 as the fulcrum and the axis parallel to the X-axis as the rotation axis.

[0050] For the experimental design of flapping wing with aspect ratio greater than 5, especially the design with large span, it is difficult for a single constraint point to meet the requirements of the wing rigidity assumption. The present invention provides an experimental scheme using multiple constraint points. As a preferred embodiment, see the attached Figure 2 and attached Figure 3, the constraint points progress from a single constraint point to a double constraint point, and the corresponding main axes are in two groups, which are arranged at the two ends of the fixture 203; the two groups of main axes 204 are parallel to each other. Preferably, the slider 303 can be designed as a long strip or other strip-shaped structure, and the fixture 203 can be designed as a long strip or other strip-shaped structure, which is not limited by the present invention. In order to make the structure of the experimental device simple, the slider 303 is long and horizontally arranged, perpendicular to the main axis 204, and parallel to the span direction of the first flapping wing 5 and the second flapping wing 6; the fixture 203 is long and parallel to the slider 303, and parallel to the span direction of the first flapping wing 5 and the second flapping wing 6. There are two sets of slider sleeves 304, which are arranged at both ends of the slider 303; the two sets of slider sleeves 304 are respectively sleeved on the two sets of main shafts 204; the two sets of slider sleeves 304 through which the slider 303 passes are sleeved on the two sets of main shafts 204; the first flapping-wing connecting rod 309 and the second flapping-wing connecting rod 315 are respectively two sets, which correspond to and are connected to the two sets of slider sleeves 304; the length of the slider 303 is limited to the distance that meets the two constraint points, and the present invention does not further limit it. The connection point between the servo connecting rod 302 and the slider 303 is located between the two sets of slider sleeves 304, and the present invention does not limit the specific connection position of the slider. There are two sets of first flapping-wing connecting devices 312, which are arranged on the first flapping-wing wing 310, and correspond to and are connected to the two sets of first flapping-wing connecting rods 309; there are two sets of second flapping-wing connecting devices 317, which are arranged on the second flapping-wing wing 316, and correspond to and are connected to the two sets of second flapping-wing connecting rods 315. In this design, there are two constraint points on the first flapping wing and the second flapping wing, respectively, for a total of four constraint points, the purpose of which is to meet or improve the rigidity requirements of the flapping wing. Those skilled in the art should be able to understand that the distance between the two sets of first flapping wing connecting devices, the distance between the two sets of second flapping wing connecting devices, the distance between the two sets of slider sleeves, the length of the firmware, the length of the slider, and the distance between the two sets of main shafts match each other. Whether the distance between the two sets of first flapping wing connecting devices and the distance between the two sets of second flapping wing connecting devices are the same or how much they are respectively, the present invention does not limit it, and those skilled in the art can determine it according to the design requirements of the constraint points of the experimental device.

[0051] When in use, the distance between the two sets of main shafts is determined according to the requirements of the experimental design for the distance between the constraint points, and then the length of the firmware and the slider is determined. The servo drives the two sets of first flapping wing connecting rods and the second flapping wing connecting rods to move synchronously through the slider, and drives the first flapping wing and the second flapping wing to flap up and down at the four constraint points through the two sets of first flapping wing connecting devices and the second flapping wing connecting devices.

[0052] It is obvious that those skilled in the art can design an experimental device with three or more restraint points according to the requirements of the experimental design and further in accordance with the ideas of the present invention.

[0053] Further preferably, for the dual-constraint point experimental device of the two main axes, in order to improve the stability and rigidity of the main axes during the test, see the attached Figure 2 The experimental device for testing the mechanical properties of bionic flapping wings also includes a support connecting beam 9; the support connecting beam 9 is perpendicular to the two groups of main shafts 204, and the two ends are respectively connected to the two groups of main shafts 204. Of course, even if the support connecting beam 9 is not perpendicular to the two groups of main shafts, it does not affect the purpose of the present invention, so the present invention is not further limited to this. The support connecting beam 9 is located above the flapping wing connection end 308 and lower than the slider 303 that slides down to the lowest position of the main shaft 204, which is used to fix the main shaft 204 to make it more stable, and at the same time cannot affect the up and down sliding of the slider. When in use, the support connecting beam 9 is welded or fixed to the main shaft 204 in other ways to prevent the main shaft 204 from vibrating, moving or deforming during the test, reduce the influence of the servo on the stability of the main shaft when the servo is running, and make the flapping of the wings strictly follow the frequency emitted by the servo, further reducing the error factors.

[0054] Further, as a preferred embodiment of the flapping wing, the first flapping wing 310 and the second flapping wing 316 are both flat wings.

[0055] Further preferably, in order to reduce the weight of the experimental device itself, the slider 303 and the servo connecting rod 302 of the experimental device for testing the mechanical properties of bionic flapping wings are hollow structures; the slider 303 includes a round hole; and the main shaft 204 is made of a hollow and smooth surface pipe. In order to further ensure the stability of underwater experimental force transmission, the first flapping wing 310, the second flapping wing 316, the first flapping wing connecting device 312, the first flapping wing connecting device 317 and the flapping wing connecting end 308 are made of stainless steel waterproof material.

[0056] As another embodiment, see the attached Figure 1 and attached Figure 2 Any of the above embodiments of the experimental device for testing the mechanical properties of bionic flapping wings also includes a water tank 4, a high-speed camera 7, a laser light source 8, a capture card (not shown in the figure), a control device (not shown in the figure) and a background analysis computer (not shown in the figure); the water tank 4 is filled with liquid; the truss 1 of the experimental device is fixedly mounted above the water tank 4; the length of the main shaft 204 of the experimental device ensures that the first flapping wing 5 and the second flapping wing 6 are located below the liquid level of the water tank 4; the laser light source 8 and the high-speed camera 7 are arranged outside the water tank 4 of the experimental device; the laser light source 7 is used to irradiate the flapping wing flow field and provide a shooting light source for the high-speed camera 8; the capture card is connected to the force sensor 201 and the steering gear 301 of the experimental device; the control device includes a single-chip microcomputer and an integrated chip, which are respectively connected to the high-speed camera 8, the capture card and the steering gear 301 of the experimental device; the background analysis computer is connected to the capture card and the control device. The control device serves as the control center of the experimental device, and controls the high-speed camera 8, the steering gear 301 and the capture card to run synchronously.

[0057] In order to ensure the synchronous measurement of aerodynamic force and flow field and facilitate the calculation of phase average, when in use, the control device sends a trigger signal to trigger the servo, high-speed camera and acquisition card; the acquisition card sends a signal to the force sensor; the acquisition card is used to collect the operating data of the force sensor and the servo during the test; the acquisition card and the high-speed camera transmit data to the background analysis computer respectively to obtain the instantaneous force measurement data and the instantaneous electric power data, and the maximum thrust and average thrust coefficient data are obtained after analysis. The sampling frequency of the high-speed camera is set to one tenth of that of the force sensor. The high-speed camera takes pictures synchronously and performs phase average on the aerodynamic force.

[0058] Further preferably, the water tank 4 of the experimental device contains tracer particles; the tracer particles are hollow glass microspheres with a diameter of 5-20 μm and a density of 1.05×103 g / cm; the laser light source 7 is an 8W continuous laser, which generates a 1mm thick laser sheet light through an optical lens group, and irradiates and photographs the flow field from the side wall of the water tank 4. The present invention uses a hardware combination of a continuous laser and a high-speed camera, and adopts a particle image velocimetry method to first evenly distribute the tracer particles in the water tank; the continuous laser generates a laser sheet light, which is irradiated from the side wall of the water tank 4, and the YZ plane flow field is obtained by photographing with a high-speed camera 8; the acquisition is triggered by program synchronization control, and the acquisition card transmits the output signal of the force sensor and the voltage signal at both ends of the servo to the background analysis computer to obtain a voltage timing signal, and the force timing signal is obtained after calibration calculation, and the maximum thrust and average thrust coefficient and other data are obtained through analysis.

[0059] It should be noted that it is obvious to those skilled in the art that the present invention is not limited to the details of the above exemplary embodiments, and that the present invention can be implemented in other specific forms without departing from the spirit or essential features of the present invention. Therefore, no matter from which point of view, the embodiments should be regarded as exemplary and non-restrictive, and the scope of the present invention is defined by the appended claims rather than the above description, and it is intended that all changes falling within the meaning and scope of the equivalent elements of the claims are included in the present invention, and any figure mark in the claims should not be regarded as limiting the claims involved.

[0060] The present specification uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only used to help understand the method and core idea of ​​the present invention. At the same time, for those skilled in the art, according to the idea of ​​the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. An experimental device for testing the mechanical properties of bionic flapping wings, characterized in that: It includes a truss, a force measuring system, a driving mechanism, a water tank, a high-speed camera and a laser light source; the top of the water tank is open, and the truss is arranged above the water tank; the high-speed camera is arranged on the left or right side of the water tank, and the laser light source is arranged on the front or rear side of the water tank; the force measuring system is arranged on the top of the truss, and the driving mechanism is arranged at the bottom of the force measuring system; the driving mechanism is used to connect with the flapping wing and drive the flapping wing to move.

2. The experimental device for testing the mechanical properties of bionic flapping wings according to claim 1, characterized in that: The force measuring system includes a force sensor, a fixture bracket, a fixture and a main shaft; the top of the force sensor is connected to the top bottom surface of the truss, the bottom of the force sensor is provided with the fixture bracket, the fixture is provided at the bottom of the fixture bracket, and the bottom of the fixture is connected to the upper end of the main shaft.

3. The experimental device for testing the mechanical properties of bionic flapping wings according to claim 2, characterized in that: The two ends of the fixing device are respectively connected to the upper end of one of the main shafts, and the two main shafts are connected via a support connecting beam.

4. The experimental device for testing the mechanical properties of bionic flapping wings according to claim 1, characterized in that: The driving mechanism includes a servo, a servo connecting rod, a slider, a slider sleeve, a flapping-wing connecting end, a flapping-wing connecting rod, a first connecting fulcrum, a flapping-wing connecting device, a first end point, a second end point and a second connecting fulcrum; the servo is arranged on a firmware in the force measuring system; the servo connecting rod of the servo is connected to the slider, the slider sleeve is connected to the slider, and the slider sleeve is slidably sleeved on the main shaft in the force measuring system; a first connecting fulcrum is respectively arranged on both sides of the slider sleeve; the flapping-wing connecting end is arranged at the lower end of the main shaft in the force measuring system, and a second connecting fulcrum is respectively arranged on both sides of the flapping-wing connecting end; one end of the flapping-wing connecting rod is rotatably connected to the first connecting fulcrum, the other end of the flapping-wing connecting rod is rotatably connected to one end of the flapping-wing connecting device, and the other end of the flapping-wing connecting device is rotatably connected to the second connecting fulcrum; the flapping-wing connecting device is used to clamp the flapping wings.

5. The experimental device for testing the mechanical properties of bionic flapping wings according to claim 4, characterized in that: The servo connecting rod comprises a first servo connecting rod and a second servo connecting rod; one end of the first servo connecting rod is connected to the output shaft of the servo, the other end of the first servo connecting rod is rotatably connected to one end of the second servo connecting rod, and the other end of the second servo connecting rod is rotatably connected to the slider.

6. The experimental device for testing the mechanical properties of bionic flapping wings according to claim 4, characterized in that: The flapping-wing connecting device includes a first hinge and a second hinge; the middle part of the first hinge is connected to one end of the first hinge connecting rod, and the second hinge connecting rod is provided at one end of the second hinge; the middle part of the first hinge and one end of the second hinge are respectively located on both sides of the flapping wing, and are connected to the flapping wing by screws, the other end of the first hinge connecting rod is rotatably connected to the flapping-wing connecting rod, and the second hinge connecting rod is rotatably connected to the second connecting fulcrum of the flapping-wing connecting end.

7. The experimental device for testing the mechanical properties of bionic flapping wings according to claim 1, characterized in that: Tracer particles are arranged in the water tank.

8. The experimental device for testing the mechanical properties of bionic flapping wings according to claim 7, characterized in that: The tracer particles are hollow glass microspheres with a diameter of 5-20 μm and a density of 1.05×10 3 g / cm 3 .

9. The experimental device for testing the mechanical properties of bionic flapping wings according to claim 1, characterized in that: The laser light source is a continuous laser, which generates a 1mm thick laser sheet light through an optical lens group, and illuminates the flow field from the side wall of the water tank to shoot.

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