Fluid-driven bionic robotic fish utilizing post-buckling deformation of open thin plate

Abstract

The invention discloses a fluid-driven bionic robotic fish utilizing post-buckling deformation of an open thin plate. The fluid-driven bionic robotic fish comprises a trunk and soft pectoral fins arranged on the two sides of the trunk. The trunk is cylindrical, and a telescopic silicon capsule body is fixed in the trunk. And the two sliding blocks are driven to be close to or far away from each other through the telescopic deformation of the silicon capsule body driven by fluid. The front edge of the soft pectoral fin is an open thin plate, and the sliding block pulls the open thin plate to achieve large deformation outside a rear buckling surface and drive the TPU film on the rear edge of the pectoral fin to fluctuate. Reciprocating deformation of the silicon capsule body and the opening thin plate is achieved by controlling pumping and filling of fluid, the soft pectoral fin periodically pushes water, and finally the robotic fish is pushed to swim forwards. The fluid-driven bionic robotic fish based on buckling deformation of the open thin plate has the advantages of being large in driving amplitude, high in driving frequency, simple in structure, high in swimming speed, low in cost and the like, can quickly swim on the water surface or in water, and can be applied to seabed resource detection, marine environment monitoring, undersea biological observation and the like.

Description

Technical Field

[0001] The present invention relates to the technology of bionic robotic fish, and particularly to a fluid-driven bionic robotic fish that utilizes the post-buckling deformation of an open thin plate. Background Art

[0002] A bionic robotic fish is an underwater robot inspired by biology and can help complete important tasks such as exploring the ocean and implementing underwater environmental monitoring. Its motion mode underwater is completely different from that of traditional rigid robots propelled by propellers. The most common motion propulsion modes of underwater organisms include the propulsion mode using the swinging of the body and caudal fin and the propulsion mode using the swinging of the symmetrical pectoral fins on both sides of the body. Therefore, the motion behavior of the soft bionic fish that mimics these propulsion motion modes enables it to be closer to underwater organisms, avoiding the problems of high motor system noise and poor concealment, thereby achieving a wider range of interactions with underwater organisms.

[0003] Common soft robots mostly use fluid drive or some soft intelligent materials for drive, such as shape memory alloys, liquid crystal elastomers, dielectric elastomers, and ionic polymer metal composites, etc. However, the current intelligent soft materials cannot achieve both large motion amplitudes and fast response speeds at the same time, resulting in insufficient driving force or driving speed, and making the flexibility of the robot worse. Therefore, how to design a soft bionic fish with flexibility, bionic motion mode, large driving force, and strong flexibility is still a problem to be solved. Summary of the Invention

[0004] The purpose of the present invention is to improve the disadvantages of traditional bionic fish robots, such as low driving speed, insufficient driving force, complex driving structure, and difficulty in mimicking the swimming form of marine organisms, and to provide a fluid-driven manta ray-like robotic fish that utilizes the post-buckling deformation of an open thin plate.

[0005] The technical solution adopted by the present invention is as follows:

[0006] A fluid-driven bionic robotic fish that utilizes the post-buckling deformation of an open thin plate. The inventive concept is that a fluid-driven silicone capsule can achieve reciprocating telescopic deformation, thereby generating reciprocating linear motion. When the fluid is pumped out to make it contract, the open thin plate is squeezed at the opening, thereby generating a large out-of-plane post-buckling deformation (swinging out of the plane); when the fluid is filled to make it elongate, the open thin plate returns to its original planar state. Using the reciprocating deformation of the open thin plate as the power for the swinging of the pectoral fins of the bionic robotic fish, driving the TPU film to achieve the undulation of the overall pectoral fins, thereby pushing the water body and achieving the purpose of forward propulsion.

[0007] A fluid-driven bionic robotic fish utilizing the post-buckling deformation of an open thin plate provided by the present invention includes a trunk and soft pectoral fins provided on both sides of the trunk; the trunk includes a rigid outer shell, a fluid-driven silicon capsule body, a front slider, and a rear slider provided inside the rigid outer shell; the front and rear sliders are respectively bonded to the front end and the rear end of the fluid-driven silicon capsule body; a slide rail parallel to the axis of the fluid-driven silicon capsule body is provided on the rigid outer shell, so that the front and rear sliders can perform linear motion along the slide rail; the soft pectoral fin includes a TPU film and an open thin plate, and the TPU film is fixedly connected to the open thin plate; a rigid rod is fixedly connected to the open thin plate, and the rigid rod is connected to the front and rear sliders through a Hooke hinge.

[0008] The fluid-driven silicon capsule body is cast from silica gel, is hollow inside, and can use a fluid, that is, a gas or a liquid, for driving through an externally connected flexible thin tube. After casting, the front and rear end faces of the fluid-driven silicon capsule body are respectively fixed to the front slider and the rear slider through bonding.

[0009] The rigid outer shell includes two parts, namely an upper shell cover and a lower shell cover, which are fixedly combined on both sides of the upper shell cover and the lower shell cover, and are in a cylindrical shape after being combined.

[0010] In order to be able to fix the relative position between the fluid-driven silicon capsule body and the rigid outer shell, clamping plates integrated with the upper and lower shell covers are respectively provided on the inner sides of the upper and lower covers. After the fluid-driven silicon capsule body is placed inside the upper and lower covers, the clamping plates can be stuck at the middle groove thereof to fix the central cross-section of the fluid-driven silicon capsule body, so that the axis of the fluid-driven silicon capsule body coincides with the axis of the outer shell, so that it can only expand and contract along the axis relative to its central cross-section. This setting can effectively play a role in fixing the axis of the fluid-driven silicon capsule body and prevent the overall axial movement of the fluid-driven silicon capsule body. Withdrawing the fluid from the fluid-driven silicon capsule body to realize the contraction deformation, driving the front and rear sliders to approach its central cross-section; filling the fluid into the fluid-driven silicon capsule body to realize the elongation deformation, driving the front and rear sliders to move away from its central cross-section. In order to avoid undesired bending of the fluid-driven silicon capsule body, a slide rail is provided inside the rigid outer shell, so that the front and rear sliders can only perform linear motion along the slide rail parallel to the axis of the fluid-driven silicon capsule body, avoiding bending deformation of the fluid-driven silicon capsule body.

[0011] On both sides of the front and rear sliders, four rigid rods are respectively connected through Hooke hinges. That is, there is a hinge pair between the Hooke hinge and the slider, and there is a hinge pair between the Hooke hinge and the rigid rod, thus releasing the rotational constraints in two directions between the slider and the rigid rod. The rotating pair is fixed by a hinge cover, so as to limit the Hooke hinge to only rotate around the axis of the rigid rod. Further, the four rigid rods are respectively fixedly connected to the symmetrically arranged open thin plates on both sides.

[0012] The open thin plate is made of a PVC thin sheet through laser cutting. Its opening angle α is the key design parameter that determines the post-buckling large deformation effect of the open thin plate. By designing different opening angles α, the degree of post-buckling deformation can be significantly affected, that is, the maximum angle η at which the open thin plate swings out of the plane. max , and its calculation formula is as follows:

[0013]

[0014] When α ranges from 0 to 180°, the corresponding swinging angle η max is between 0 and 120°. Through design, when the opening angle α is between 10° and 170°, the bionic fish can swim more effectively.

[0015] The open thin plate is bonded to the leading edge of the TPU film. The two are important components of the soft pectoral fin and are also the key to imitating the manta ray to enable the bionic fish to swim. There is a very small gap between the rear halves of the upper shell cover and the lower shell cover after they are combined. The gap is slightly smaller than the thickness of the TPU film. The gap is used to clamp the TPU film on both sides of the trunk main body, playing a role in fixing the rear side edge of the TPU film and making it easier for the TPU film to achieve the effect of imitating the pectoral fin undulation of the manta ray. The rear side edge of the TPU film can also be fixed to the rigid outer shell by bonding.

[0016] In order to make the soft pectoral fin fluctuate, during the process of the front and rear end sliders approaching the card plate, the linear motion between the front and rear end sliders releases the rotation constraints in two directions through the Hooke's hinge, and respectively drives the ends of the two rigid rods located on both sides of the trunk and fixed to the same open thin plate to move closer to each other, so that the open thin plate undergoes a large post-bending deformation (the open thin plate is greatly tilted in a plane perpendicular to the axis of the trunk, that is, the open thin plate swings out of the plane) and stores elastic potential energy, thereby driving the leading edge of the soft pectoral fin to swing upward; then, during the process of the front and rear end sliders moving away from the card plate, the front and rear end sliders respectively drive the ends of the two rigid rods located on both sides of the trunk and fixed to the same open thin plate away from each other, and the elastic potential energy stored in the open thin plate is released, recovering from the flexed state to the planar state (recovering to the initial state in a plane perpendicular to the main axis of the trunk) and driving the leading edge of the soft pectoral fin to swing downward. The open thin plate swings up and down alternately, driving the soft pectoral fin to generate fluctuations, thereby pushing the water body to generate forward thrust, so that the bionic fish can imitate the manta ray to swim forward.

[0017] The beneficial effects of the present invention are:

[0018] The bionic robotic fish of the present invention utilizes the post-bending deformation of an open thin plate. Since the open thin plate has the characteristic of being greatly deformed by bending outwards after being squeezed, the fluid-driven silicon capsule body only needs a small displacement to make the deformation angle of the open thin plate very large. After design, the maximum deformation angle can reach 116°, thereby achieving the effect of increasing the swing amplitude of the soft pectoral fin.

[0019] The fluid-driven silicon capsule body can be driven by any form of fluid. In particular, when gas is selected, due to the characteristics of low gas density and low resistance, the response speed of the fluid-driven silicon capsule body can be very fast, and the expansion and contraction frequency can reach 20Hz, thereby achieving the effect of increasing the driving frequency. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a schematic structural diagram of a fluid-driven bionic fish robot utilizing post-buckling deformation of an open thin plate according to the present invention;

[0021] Figure 2 This is a schematic diagram of the torso split structure;

[0022] Figure 3 This is a cross-sectional view of the torso after installation;

[0023] Figure 4 This is a schematic diagram of the structure of the soft pectoral fin;

[0024] Figure 5 It is a schematic diagram of the structure after the main driving components are connected;

[0025] Figure 6Schematic structural diagram of the trunk and the deformable state of the opening thin plate in the driving state of the bionic fish;

[0026] Figure 7 Schematic diagram of the size of the opening thin plate and its states before and after deformation;

[0027] Figure 8 Curve relationship diagram of the opening angle and the degree of deformation (maximum swing angle) of the opening thin plate;

[0028] Wherein: 1 fluid-driven silicone capsule, 2 front slider, 3 rear slider, 4 upper shell cover, 5 lower shell cover, 6 Hooke hinge, 7 rigid rod, 8 hinge cover, 9 opening thin plate, 10 TPU film. Detailed implementation manners

[0029] The following further explains the solution of the present invention with reference to the accompanying drawings.

[0030] As Figure 1 shown, a fluid-driven bionic robotic fish using post-buckling deformation of an opening thin plate includes a trunk and soft pectoral fins symmetrically arranged on both sides of the trunk. The trunk is composed of a fluid-driven silicone capsule 1, a front slider 2 adhesively bonded to the front end of the fluid-driven silicone capsule 1, a rear slider 3 adhesively bonded to the rear end of the fluid-driven silicone capsule 1, an upper shell cover 4, and a lower shell cover 5; the soft pectoral fins include an opening thin plate 9 and a TPU film 10; a rigid rod 7 is fixedly connected to the opening thin plate 9, and the rigid rod 7 is connected to the front slider 2 and the rear slider 3 through a Hooke hinge 6. Symmetrically arranged grooves are provided on the rigid rod 7 and the hinge cover 8. After the two are fixedly connected, the Hooke hinge 6 is placed in the groove, so that there is only one degree of freedom of rotation between the Hooke hinge 6 and the rigid rod 7.

[0031] The fluid-driven silicone capsule 1 is cast from silicone, is hollow inside, and can use fluid, that is, gas or liquid, for driving through an externally connected flexible thin tube. As Figure 2 shown, after casting, the front and rear end faces of the fluid-driven silicone capsule 1 are respectively fixed to the front slider 2 and the rear slider 3 through adhesion. The upper shell cover 4 and the lower shell cover 5 form a rigid outer shell after being combined, which is cylindrical, and are fixedly combined through fixation on both sides of the upper shell cover 4 and the lower shell cover 5. In order to be able to fix the relative positions between the fluid-driven silicone capsule 1 and the upper shell cover 4 and the lower shell cover 5, as Figure 3As shown, clamping plates are respectively arranged on the inner sides of the upper shell cover 4 and the lower shell cover 5. After the fluid-driven silicon capsule body 1 is placed inside the upper shell cover 4 and the lower shell cover 5, the clamping plates can be clamped at the middle groove of the fluid-driven silicon capsule body 1, so that the axis of the fluid-driven silicon capsule body 1 coincides with the axis of the rigid shell. This setting can effectively fix the axis of the fluid-driven silicon capsule body 1 and prevent the overall axial movement of the fluid-driven silicon capsule body 1.

[0032] The main body of the soft pectoral fin is the open thin plate 9 and the TPU film 10, both of which are cut into specific shapes by a laser cutting machine. The opening angle of the open thin plate 9 is the key design parameter that determines the post-buckling deformation effect of the open thin plate. For example, Figure 8 , by designing different opening angles α, the degree of post-buckling deformation can be significantly affected, that is, the maximum angle η at which the open thin plate swings out of the plane. max . The calculation formula for the relationship between the two is as follows:

[0033]

[0034] The outer contour of the TPU film 10 is also the key to determining the swimming effect of the bionic fish. The open thin plate 9 and the TPU film 10 are fixed by bonding. One side of the open thin plate 9 is bonded to a specific position on the TPU film 10 to form the soft pectoral fin. In addition, as Figure 4 and Figure 5 shown, some connecting components also need to be assembled on the soft pectoral fin to realize the connection between the soft pectoral fin and the trunk and relieve part of the movement constraints. They include: the Hooke hinge 6 hinged to the front slider 2 and the rear slider 3 - one Hooke hinge 6 is hinged on each of the left and right sides of the front slider 2, and one Hooke hinge 6 is also hinged on each of the left and right sides of the rear slider; the rigid rod 7 fixed on the open thin plate 9 - there are two soft pectoral fins on both sides of the trunk, so there are two symmetrically arranged open thin plates 9, and each open thin plate 9 needs to be fixed with two rigid rods 7, so a total of 4 rigid rods 7 are needed to be hinged with 4 Hooke hinges 6; 4 hinge caps 8 - in order to fix the rotating pair between the Hooke hinge 6 and the rigid rod 7, 4 hinge caps are needed to be fixed with 4 rigid rods 7. Symmetrically arranged grooves are provided inside the two to place the Hooke hinge 6, so as to limit the Hooke hinge 6 from moving axially in the direction of the axis of the rigid rod 7 and only be able to rotate around the axis of the rigid rod 7. This setting can relatively simply fix the relative positions of the three without hindering the relative movement of rotation.

[0035] In addition to being connected on the kinematic pair by four Hook hinges 6, the two soft pectoral fins also need to be fixedly connected to the rear sides of the two TPU films 10 with the rigid shell. There is a small gap between the rear half of the upper shell cover 4 and the lower shell cover 5 after merging, and the gap is slightly smaller than the thickness of the TPU film 10. The gap is used to clamp the TPU films 10 on both sides of the trunk body, which plays a role in fixing the rear side of the TPU film 10. The rear side of the TPU film can also be fixed to the rigid shell by bonding, so that the TPU film can more easily achieve the effect of imitating the fluctuation of the pectoral fin of the manta ray.

[0036] The above is the installation instructions for the components of the bionic robot fish. The following will introduce how the various components work together to enable the soft-bodied fish to swim forward.

[0037] Fluid is extracted from the fluid-driven silicon capsule body 1 to achieve contraction deformation, driving the front slider 2 and the rear slider 3 to approach the central section of the fluid-driven silicon capsule body 1; fluid is filled into the fluid-driven silicon capsule body 1 to achieve extension deformation, driving the front slider 2 and the rear slider 3 away from the central section of the fluid-driven silicon capsule body 1. In order to prevent the fluid-driven silicon capsule body 1 from undesirable bending, the front half of the housing upper cover 4 and the housing lower cover 5 have a slide rail, so that the front slider 2 and the rear slider 3 can move linearly along the slide rail parallel to the axis of the fluid-driven silicon capsule body 1.

[0038] In order to make the soft pectoral fin swing, during the process of the front slider 2 and the rear slider 3 approaching the central section of the fluid-driven silicone capsule body 1, the linear displacement between the front slider 2 and the rear slider 3 releases the rotation constraints in two directions through the Hooke hinge 6, and respectively drives the ends of the two rigid rods 7 located on both sides of the trunk and fixed to the same open thin plate 9 to approach each other, so that the open thin plate 9 undergoes a large post-bending deformation (the open thin plate 9 is greatly tilted in a plane perpendicular to the axis of the trunk, that is, the open thin plate swings out of the plane) and stores elastic potential energy, thereby driving the leading edge of the soft pectoral fin to swing upward, as shown in FIG. Figure 6 and Figure 7 As shown; then, during the process of the front slider 2 and the rear slider 3 moving away from the central section of the fluid-driven silicon capsule body 1, the front slider 2 and the rear slider 3 respectively drive the ends of the two rigid rods 7 fixed to the same open thin plate 9 on both sides of the trunk to move away, and the elastic potential energy stored in the open thin plate 9 is released, so that it recovers from the flexed state to the plane state (recovers to the initial plane state in the plane perpendicular to the trunk axis), and drives the leading edge of the soft pectoral fin to swing downward. The open thin plate 9 swings up and down alternately, driving the soft pectoral fin to fluctuate, thereby pushing the water body to generate forward thrust, so that the bionic fish can imitate the manta ray to swim forward.

[0039] In this example, the opening angle of the opening thin plate is 79°. The front slider 2 and the rear slider 3 can achieve a linear telescopic motion of 35 mm driven by the fluid-driven silicone capsule 1, and the swing angle generated by driving the opening thin plate 9 can reach 55°. This realizes the effect of converting small displacement input into large swing output and meets the requirement of large driving amplitude. In terms of fluid selection, when using gas as the driving fluid of the fluid-driven silicone capsule 1, due to the characteristics of low density and low resistance of the gas, the reciprocating telescopic frequency of the fluid-driven silicone capsule 1 can reach 20 Hz, meeting the requirement of high driving frequency. Therefore, the swimming speed is considerable.

[0040] The fluid-driven bionic fish using the post-buckling deformation of the opening thin plate of the present invention has the advantages of large driving amplitude, high driving frequency, being able to imitate the propulsion form of marine organisms, having a delicate and simple structure, fast swimming speed, low cost, etc. It can achieve fast swimming on the water surface or in water and can meet the various needs of marine fields such as undersea resource exploration, marine environment monitoring, and underwater biological observation.

Claims

1. A fluid-driven bionic robotic fish utilizing post-buckling deformation of an open thin plate, characterized in that: It includes a trunk and soft pectoral fins arranged on both sides of the trunk; the trunk includes a rigid shell, and a fluid-driven silicon capsule body, a front slider and a rear slider arranged in the rigid shell; the front and rear sliders are respectively bonded to the front and rear ends of the fluid-driven silicon capsule body; the rigid shell is provided with a slide rail parallel to the axis of the fluid-driven silicon capsule body, so that the front and rear sliders can move linearly along the slide rail; the soft pectoral fins include a TPU film and an open thin plate, and the TPU film is fixedly connected to the open thin plate; the open thin plate is fixedly connected to a rigid rod, and the rigid rod is connected to the front and rear sliders through a Hooke's hinge; the reciprocating deformation of the open thin plate serves as the power for the pectoral fins of the bionic robot fish to swing: when the front slider and the rear slider are close to each other, the open thin plate is squeezed at the opening, thereby generating an out-of-plane post-buckling deformation; when the front slider and the rear slider are away from each other, the open thin plate returns to its initial plane state.

2. The fluid-driven bionic robotic fish utilizing post-buckling deformation of an open thin plate according to claim 1, characterized in that: The rigid shell is cylindrical and includes an upper shell cover and a lower shell cover. A clamp is arranged inside the upper shell cover and the lower shell cover. The clamp is used to fix the central cross-section of the fluid-driven silicon capsule body so that the fluid-driven silicon capsule body can only expand and contract relative to its central cross-section along the axis.

3. The fluid-driven bionic robotic fish utilizing post-buckling deformation of an open thin plate according to claim 1, characterized in that: The fluid-driven silicon capsule body is in the shape of a bellows, hollow inside, and driven by gas or liquid; fluid is extracted from the fluid-driven silicon capsule body to achieve contraction deformation, driving the front and rear end sliders to move closer to each other; fluid is filled into the fluid-driven silicon capsule body to achieve elongation deformation, driving the front and rear end sliders to move away from each other.

4. The fluid-driven bionic robotic fish utilizing post-buckling deformation of an open thin plate according to claim 1, characterized in that: The opening angle of the open thin plate ranges from 10° to 170°.

5. The fluid-driven bionic robotic fish utilizing post-buckling deformation of an open thin plate according to claim 1, characterized in that: The two sides of the front and rear end sliders are respectively connected to four rigid rods through four Hook hinges, so as to release the rotation constraints between the sliders and the rigid rods in two directions.

6. The working method of a fluid-driven bionic robotic fish using post-buckling deformation of an open thin plate according to any one of claims 1 to 5, characterized in that: The fluid-driven silicon capsule body and the open thin plate undergo reciprocating deformation, driving the soft pectoral fins to generate fluctuations, thereby driving the water body to generate forward thrust, so that the bionic robotic fish can swim forward.

7. The working method of the fluid-driven bionic robotic fish using post-buckling deformation of an open thin plate according to claim 6, characterized in that: The reciprocating deformation of the fluid-driven silicone capsule body and the open thin plate drives the soft pectoral fin to fluctuate, and the specific method is: when the front and rear end sliders approach each other, they respectively drive the ends of the two rigid rods located on both sides of the trunk and fixed to the same open thin plate to approach each other, so that the open thin plate undergoes rearward bending deformation and stores elastic potential energy, thereby driving the TPU film to swing upward; then, when the front and rear end sliders move away from each other, the front and rear end sliders respectively drive the ends of the two rigid rods located on both sides of the trunk and fixed to the same open thin plate to move away from each other, the elastic potential energy stored in the open thin plate is released, and it returns to its initial planar state, thereby driving the TPU film to return to its initial state.

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