A worm-like variable stiffness biomimetic robotic fish

Abstract

The application discloses a kind of earthworm-like variable stiffness biomimetic robotic fish, it includes head;Pneumatic device is arranged in head;Paper folding structure, one end is connected with head in axial direction;Pneumatic device is connected with paper folding structure, and it is used to inflate or from paper folding structure inside air extraction, to drive paper folding structure to stretch out and shrink in axial direction;Drive device is arranged in head;Pulling line structure is respectively connected with drive device and paper folding structure, to drive paper folding structure bending under the driving of drive device.This application combines paper folding structure with pulling line structure, by the inflation and air extraction of paper folding structure by pneumatic device, adjust the pressure inside paper folding mechanism, carry out the stiffness adjustment of fish body, produce earthworm-like peristalsis swimming, significantly improve the passability in narrow space operation.

Description

Technical Field

[0001] This invention relates to the field of robotic fish technology, and more particularly to a biomimetic robotic fish with variable stiffness similar to an earthworm. Background Technology

[0002] Based on their propulsion methods, biomimetic robotic fish are mainly divided into two categories: those using a body-tail fin propulsion system and those using a middle fin-to-fin propulsion system. Compared to the latter, the former offers higher propulsion efficiency, faster start-up speed, and the ability to perform high-speed underwater operations for extended periods, attracting numerous inventors and researchers to develop this type of robotic fish. However, research on the impact of body stiffness on swimming performance is still in its infancy, and the morphological adjustment and control of existing variable stiffness biomimetic robotic fish are severely limited, with most unable to effectively extend, retract, or change shape.

[0003] For example, the patent with patent number CN117985211A discloses that the heating temperature of the heating element is controlled by a temperature control device to adjust the rigidity of the tail fin skeleton. However, the flexibility is low when making large tail swings, and it cannot complete earthworm-like swimming, resulting in low passability when working in narrow spaces.

[0004] Therefore, existing technologies still need to be improved and developed. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a biomimetic robotic fish with variable stiffness similar to an earthworm, which aims to achieve earthworm-like peristaltic swimming and improve the passability of working in narrow spaces, in order to address the above-mentioned deficiencies of the prior art.

[0006] The technical solution adopted by this invention to solve the technical problem is as follows:

[0007] A biomimetic robotic fish with variable stiffness, resembling an earthworm, includes a head and also includes:

[0008] A pneumatic device is installed inside the head;

[0009] The origami structure has one axial end connected to the head; the pneumatic device is connected to the origami structure and is used to inflate or extract air from the origami structure to drive the origami structure to extend and retract axially.

[0010] A drive unit is disposed inside the head.

[0011] The earthworm-like variable stiffness biomimetic robotic fish, wherein the pneumatic device includes:

[0012] Gas cylinder;

[0013] A reversing valve is connected to the folding structure;

[0014] An air pump is located between the gas storage cylinder and the reversing valve, and is connected to both the gas storage cylinder and the reversing valve.

[0015] The earthworm-like variable stiffness biomimetic robotic fish also includes:

[0016] A drawstring structure is connected to both the drive device and the origami structure, so as to drive the origami structure to bend under the drive of the drive device.

[0017] The earthworm-like variable stiffness biomimetic robotic fish, wherein the pull-wire structure includes:

[0018] The first pull line is located on one radial side of the origami structure, and one end of the first pull line is connected to the driving device, and the other end is connected to the origami structure.

[0019] The second pull line is symmetrically arranged on the other side of the radial direction of the origami structure, and one end of the second pull line is connected to the driving device, and the other end is connected to the origami structure.

[0020] The earthworm-like variable stiffness biomimetic robotic fish, wherein the driving device includes:

[0021] Servo motor;

[0022] A rudder disc, mounted on the servo motor, is used to rotate along a horizontal plane under the drive of the servo motor.

[0023] The first pull cable and the second pull cable are located on both sides of the rudder and are both connected to the rudder.

[0024] The earthworm-like variable stiffness biomimetic robotic fish, wherein the pull-wire structure further includes:

[0025] The first fixing plate is disposed on the origami structure and can reciprocate along the axial direction with the origami structure; the first pull wire and the second pull wire are located on both sides of the first fixing plate and are both connected to the first fixing plate.

[0026] The earthworm-like variable stiffness biomimetic robotic fish, wherein the pull-wire structure further includes:

[0027] The second fixing plate is disposed on the origami structure and located between the head and the first fixing plate;

[0028] The second wire fixing plate is provided with a first mounting hole and a second mounting hole. The first pull wire passes through the first mounting hole and is in clearance fit with the first mounting hole; the second pull wire passes through the second mounting hole and is in clearance fit with the second mounting hole.

[0029] The earthworm-like variable stiffness biomimetic robotic fish also includes:

[0030] A tail fin is located at the end of the origami structure opposite to the head.

[0031] Two pusher plate structures are symmetrically arranged on both sides of the tail fin.

[0032] The earthworm-like variable stiffness biomimetic robotic fish, wherein the pusher plate structure includes:

[0033] A flexible connector is used to connect to the tail fin;

[0034] The first push plate is disposed on the flexible connector;

[0035] The second push plate is disposed on the flexible connector and located on the side of the first push plate away from the origami structure.

[0036] The earthworm-like variable stiffness biomimetic robotic fish, wherein the pusher plate structure further includes:

[0037] An elastic pad is disposed on the flexible connector and located between the first push plate and the second push plate.

[0038] Beneficial effects: In this application, the origami structure is combined with the pull-string structure. The pneumatic device is used to inflate and de-inflate the origami structure, thereby adjusting the internal pressure of the origami mechanism and realizing the spatial folding and stretching deformation of the origami structure. This allows for the adjustment of the stiffness of the fish body, producing earthworm-like wriggling movements, and significantly improving the maneuverability in narrow spaces. Attached Figure Description

[0039] Figure 1 This is a schematic diagram of the overall structure of the earthworm-like variable stiffness bionic robotic fish described in this invention.

[0040] Figure 2 This is a schematic diagram of the internal structure of the earthworm-like variable stiffness bionic robotic fish described in this invention;

[0041] Figure 3 This is a partially exploded structural diagram of the earthworm-like variable stiffness bionic robotic fish described in this invention.

[0042] Figure 4 This is a schematic diagram of the assembly structure of the driving device, the first pull wire, and the second pull wire described in this invention;

[0043] Figure 5 This is a comparison diagram of different turning states of the earthworm-like variable stiffness bionic robotic fish described in this invention;

[0044] Figure 5 In the diagram, a is a schematic diagram of the turning of the earthworm-like variable stiffness bionic robotic fish when the second pull line is tightened in this invention;

[0045] Figure 5 In diagram b, the earthworm-like variable stiffness bionic robotic fish described in this invention is moving in a straight line.

[0046] Figure 5 c is a schematic diagram of the turning of the earthworm-like variable stiffness bionic robotic fish when the first pull line is tightened in this invention;

[0047] Figure 6 This is a comparison diagram of the state of the earthworm-like variable stiffness bionic robotic fish when the origami structure described in this invention extends to the tail.

[0048] Figure 6 In the diagram below, d represents the usage state of the earthworm-like variable stiffness bionic robotic fish under natural conditions.

[0049] Figure 6 In the figure above, 'e' represents the usage state of the earthworm-like variable stiffness bionic robotic fish when the origami structure described in this invention is initially extended.

[0050] Figure 6 Figure f is a reference diagram showing the usage state of the earthworm-like variable stiffness bionic robotic fish when the origami structure described in this invention continues to extend.

[0051] Figure 7 This is a comparison diagram of the state of the earthworm-like variable stiffness bionic robotic fish when the origami structure described in this invention retracts towards the head;

[0052] Figure 7 In the figure above, g is a reference diagram showing the usage state of the earthworm-like variable stiffness bionic robotic fish when the origami structure described in this invention is extended.

[0053] Figure 7 The figure in the middle is a reference diagram of the usage state of the earthworm-like variable stiffness bionic robotic fish when the origami structure described in this invention is initially retracted.

[0054] Figure 7 The diagram in Figure k is a reference diagram of the usage state of the earthworm-like variable stiffness bionic robotic fish when the origami structure described in this invention continues to retract to its natural state. Detailed Implementation

[0055] The embodiments of the present invention will be described below with reference to the accompanying drawings and preferred embodiments. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be understood that the preferred embodiments are only for illustrating the present invention and not for limiting the scope of protection of the present invention.

[0056] It should be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of the present invention. Therefore, the drawings only show the components related to the present invention and are not drawn according to the actual number, shape and size of the components in the actual implementation. In the actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.

[0057] This application provides a biomimetic robotic fish with variable stiffness, similar to an earthworm, such as... Figure 1 and Figure 2 As shown, the earthworm-like variable stiffness bionic robotic fish includes: a head 1, a pneumatic device 2, an origami structure 3, and a driving device 4; the pneumatic device 2 is disposed inside the head 1; one axial end of the origami structure 3 is connected to the head 1; the pneumatic device 2 is connected to the origami structure 3 and is used to inflate or extract air from the origami structure 3 to drive the origami structure 3 to extend and retract axially; the driving device 4 is disposed inside the head 1.

[0058] Specifically, the origami structure 3 is tubular, meaning it has an internal cavity to hold gas. The origami structure 3 is composed of multiple origami units arranged linearly along the axial direction. Each origami unit has a rhomboid radial side with a concave center fold to form an angle β. The pneumatic device 2 is connected to the origami structure 3 to inflate and de-inflate the cavity, thereby changing the pressure within the cavity and altering the shape of the origami structure 3.

[0059] When the origami structure 3 is inflated, the included angle β (e.g.) Figure 7 As shown in g), the origami structure 3 extends axially, and the axial length of the origami structure 3 increases (e.g., as shown in g). Figure 6 As shown), this increases the rigidity of the fish's body, meeting the needs of rapid swimming; when air is drawn out from the origami structure 3, the β angle decreases, and the origami structure 3 retracts axially (as shown). Figure 7 As shown, the axial length of the origami structure 3 is reduced, decreasing the stiffness of the fish body and making it softer, facilitating changes in swimming direction and turning. The design of the origami mechanism allows it to change during gas injection or emission; this "spatial folding" allows the robotic fish to control its shape by adjusting the amount of gas. Through different folding patterns of the origami structure 3, the robotic fish can expand or contract its volume, thereby adjusting its swimming stiffness and flexibility. In relatively narrow waters, utilizing the spatial folding of the origami structure 3, and in conjunction with the pneumatic device 2 to pump and inflate the origami structure 3, the fish body can expand and contract, achieving swimming with variable stiffness and volume, thus effectively improving the flexibility and adaptability of the bionic robotic fish.

[0060] Earthworm-like undulation is a biomimetic movement pattern that mimics the wave-like muscle contractions and expansions of earthworms or similar organisms during movement. When earthworms crawl in the soil, they propel their bodies segment by segment forward and backward through a series of continuous, undulating muscle contractions and relaxations, creating a wave-like undulating motion. In this application, the drive device 4, combined with the pull-wire structure 5, mimics the muscle closure of fish. The drive device 4 drives the pull-wire structure 5, pulling the fish-shaped cavity formed by the origami structure 3, allowing the biomimetic robotic fish to perform large-amplitude tail swings, thereby generating thrust. In confined spaces, the coordinated movement of the origami mechanism and the pull-wire mechanism produces earthworm-like undulating swimming, significantly improving maneuverability in narrow spaces.

[0061] Therefore, in this application, the air pressure inside the origami mechanism is adjusted by inflating and deflating the origami structure 3 using the pneumatic device 2, thereby realizing the spatial folding and stretching deformation of the origami structure 3, and thus adjusting the stiffness of the fish body. This allows the robotic fish to adapt to different task requirements and environmental changes, producing earthworm-like wriggling movements, and significantly improving its passability in narrow spaces.

[0062] One embodiment of this application, such as Figure 2 and Figure 3 As shown, the pneumatic device 2 includes an air storage cylinder 21, a reversing valve 22, and an air pump 23; the reversing valve 22 is connected to the folding structure 3; the air pump 23 is disposed between the air storage cylinder 21 and the reversing valve 22, and is connected to the air storage cylinder 21 and the reversing valve 22 respectively.

[0063] Specifically, the gas storage cylinder 21, the air pump 23, the reversing valve 22, and the origami structure 3 are connected in sequence; the gas storage cylinder 21 is used to store compressed gas, the gas storage cylinder 21 is connected to one end of the air pump 23 through a pipe, and the other end of the air pump 23 is connected to the reversing valve 22, and the gas is transported from the gas storage cylinder 21 to the reversing valve 22 through the air pump 23.

[0064] The reversing valve 22 is a three-position four-way reversing valve. It controls the flow direction and flow rate of gas by changing the position of the valve body, thereby enabling gas to be delivered into and extracted from the origami structure 3. When the reversing valve 22 is in the inflating state, gas flows into the inner cavity (air chamber) of the origami structure 3 through the valve, pushing the origami structure 3 to expand and harden, increasing its volume and shape. When it is necessary to soften the origami structure 3 or reduce its volume, the reversing valve 22 switches to the evacuation state, and gas is discharged from the inner cavity of the origami structure 3, causing the origami structure 3 to shrink in volume, soften, and reduce its rigidity.

[0065] In one embodiment of this application, the earthworm-like variable stiffness bionic robotic fish further includes a drawstring structure 5 (such as...). Figure 3 (As shown); the pull-wire structure 5 is connected to the driving device 4 and the origami structure 3 respectively, so as to drive the origami structure 3 to bend under the drive of the driving device 4. In this application, the driving device 4 and the pull-wire structure 5 are combined to imitate the muscle closure of fish. The driving device 4 drives the pull-wire structure 5 to move, pulling the fish body cavity formed by the origami structure 3, so that the bionic robotic fish can perform a large-amplitude tail swing, thereby generating thrust.

[0066] One embodiment of this application, such as Figure 3 and Figure 4 As shown, the pull wire structure 5 includes a first pull wire 51 and a second pull wire 52; the first pull wire 51 is located on one side of the radial direction of the origami structure 3, and one end of the first pull wire 51 is connected to the driving device 4, and the other end is connected to the origami structure 3; the second pull wire 52 is symmetrically arranged on the other side of the radial direction of the origami structure 3, and one end of the second pull wire 52 is connected to the driving device 4, and the other end is connected to the origami structure 3.

[0067] Specifically, the first pull line 51 and the second pull line 52 are located on the left and right sides of the origami structure 3 and are both connected to the origami structure 3. When the driving device 4 is started, the first pull line 51 tightens or loosens, and the second pull line 52 loosens or tightens, thereby changing the shape of the fish body and realizing the bending and turning of the fish body.

[0068] The connection points between the first pull wire 51 and the driving device 4, and between the first pull wire 51 and the origami structure 3, are fixed connection points. That is, the connection points between the first pull wire 51 and the driving device 4 are positioned, and the connection points between the first pull wire 51 and the origami structure 3 are also positioned. Similarly, the connection points between the second pull wire 52 and the driving device 4 are positioned, and the connection points between the second pull wire 52 and the origami structure 3 are also positioned.

[0069] One embodiment of this application, such as Figure 2 and Figure 4 As shown, the drive device 4 includes a servo motor 41 and a servo disc 42. The servo disc 42 is mounted on the servo motor 41 and rotates along the horizontal plane under the drive of the servo motor 41. The first pull cable 51 and the second pull cable 52 are distributed on both sides of the servo disc 42 and are both connected to the servo disc 42.

[0070] Specifically, the first pull wire 51 and the second pull wire 52 are radially distributed on both sides of the rudder disk 42. In one embodiment of this invention, when the servo motor 41 is activated and drives the rudder disk 42 to rotate clockwise, the contact length between the first pull wire 51 and the rudder disk 42 increases, and the first pull wire 51 is pulled by the rudder disk 42, causing the origami structure 3 to bend towards the first pull wire 51; when the servo motor 41 is activated and drives the rudder disk 42 to rotate clockwise, the contact length between the second pull wire 52 and the rudder disk 42 increases, and the second pull wire 52 is pulled by the rudder disk 42, causing the origami structure 3 to bend towards the second pull wire 52.

[0071] like Figure 4 As shown, an arc-shaped groove 421 is provided on the outer circumferential surface of the rudder disk 42. The arc-shaped groove 421 cooperates with the first pull wire 51 and the second pull wire 52 to accommodate the first pull wire 51 and the second pull wire 52 when the rudder disk 42 rotates, thereby limiting the first pull wire 51 and the second pull wire 52 and preventing excessive deviation when the first pull wire 51 and the second pull wire 52 are pulled and deformed, thus ensuring the stability of the bionic robotic fish when turning.

[0072] like Figure 2 and Figure 3 As shown, the pull wire structure 5 also includes a first wire fixing plate 53, which is disposed on the origami structure 3 and can reciprocate along the axial direction with the origami structure 3; the first pull wire 51 and the second pull wire 52 are located on both sides of the first wire fixing plate 53 and are both connected to the first wire fixing plate 53.

[0073] Specifically, the position of the first fixing plate 53 relative to the origami structure 3 is relatively fixed, and the connection point between the first fixing plate and the first pull wire 51 and the second pull wire 52 is also relatively fixed. Therefore, when the origami structure 3 extends or retracts, the first fixing plate 53 moves synchronously along the axial direction with the origami structure 3. The first fixing plate 53 increases the interference between the first pull wire 51, the second pull wire 52, and the origami structure 3, ensuring that the tension generated when the first pull wire 51 or the second pull wire 52 is tightened can be stably transmitted to the origami structure 3, thereby ensuring the stability of the bionic robotic fish when turning.

[0074] like Figure 2 and Figure 3 As shown, the pull wire structure 5 further includes a second wire fixing plate 54, which is disposed on the origami structure 3 and located between the head 1 and the first wire fixing plate 53; the second wire fixing plate 54 is provided with a first mounting hole and a second mounting hole, the first pull wire 51 passes through the first mounting hole and is clearance-fitted with the first mounting hole; the second pull wire 52 passes through the second mounting hole and is clearance-fitted with the second mounting hole.

[0075] Specifically, the second wire fixing plate 54 is located on the side of the first wire fixing plate 53 closer to the head 1, that is, the first wire fixing plate 53 is closer to the tail of the bionic robotic fish, and the second wire fixing plate 54 is closer to the head 1. The second wire fixing plate 54 is spaced apart from the first wire fixing plate 53, and both the first pull wire 51 and the second pull wire 52 are assembled with the second wire fixing plate 54. The clearance fit between the first pull wire 51 and the first mounting hole, and the clearance fit between the second pull wire 52 and the second mounting hole, allows both the first pull wire 51 and the second pull wire 52 to move relative to the second wire fixing plate 54; that is, the assembly point between the first pull wire 51 and the second wire fixing plate 54 is not fixed, and the assembly point between the second pull wire 52 and the second wire fixing plate 54 is not fixed. When the first pull wire 51 is tightened or the second pull wire 52 is tightened, or when the origami structure 3 is extended or retracted, the second wire fixing plate 54 can move relative to the first pull wire 51 and the second pull wire 52.

[0076] In this application, the first pull line 51 and the second pull line 52 are installed using two fixing plates, which can fix the first pull line 51 and the second pull line 52 at different locations, providing a more uniform and balanced force transmission. By setting the fixing plates at different positions on the fish's body, it can be ensured that the pull line structure 5 can effectively control the movement of the fish in multiple directions. When it is necessary to adjust the swimming direction, the two fixing plates can fix the pull lines in different directions respectively, making the fish more stable when adjusting its direction and reducing erroneous movements caused by unevenness or looseness of the first pull line 51 or the second pull line 52.

[0077] Meanwhile, if there is only one fixing plate, the tension and load of the first pull wire 51 and the second pull wire 52 will be concentrated at a single point, which may lead to excessive stress at that point, thereby affecting the service life of the first pull wire 51 and the second pull wire 52 or causing unbalanced movement. By using two fixing plates, the tension of the first pull wire 51 and the second pull wire 52 can be distributed to multiple points, reducing overload at a single point and improving the reliability and stability of the pull wire structure 5.

[0078] The cooperation between the first cable fixing plate 53 and the second cable fixing plate 54 also helps to ensure the structural symmetry of the design, allowing the robotic fish to maintain balance during propulsion and avoiding asymmetrical or unbalanced movement caused by excessively tight or loose cable on one side. Especially when high-precision control is required, the two fixing points help ensure the stability of the entire system.

[0079] One embodiment of this application, such as Figure 1 , Figure 2 and Figure 3 As shown, the earthworm-like variable stiffness bionic robotic fish also includes a dorsal fin 6, which is disposed on the second fixed plate 54.

[0080] Specifically, the dorsal fin 6 enhances the forward stability of the robotic fish, especially preventing it from tilting or rolling during swimming. Positioning the dorsal fin 6 on the more forward-facing second fixing plate 54 allows it to function more effectively during forward movement, contributing to better control of the fish's longitudinal stability. When the robotic fish swims, the dorsal fin 6 resists disturbances from the water flow, reducing up-and-down flipping or instability caused by uneven fluid distribution or water flow reaction forces. Furthermore, compared to positioning the dorsal fin 6 on the first fixing plate 53, placing it further forward on the second fixing plate 54 in this embodiment ensures that the dorsal fin 6 contacts the water flow earlier, helping to optimize the direction of water flow entering the robotic fish, preventing eddies or unstable local flows at the tail, reducing resistance, and improving propulsion efficiency. This allows for rapid stability during swimming, preventing the robotic fish from being affected by instability at the rear.

[0081] It should be noted that both the first wire-fixing plate 53 and the second wire-fixing plate 54 are partially embedded within the origami structure 3 and partially extend outside the origami structure 3, and the portions embedded within the origami structure 3 are each provided with ventilation holes 50 (e.g., Figure 3 (as shown), to ensure that gas can fill the entire inner cavity of the origami structure 3; the portion of the second fixing plate 54 extending outside the origami structure 3 is used to install the dorsal fin 6, the first pull wire 51 and the second pull wire 52; the portion of the first fixing plate 53 extending outside the origami structure 3 is used to install the first pull wire 51 and the second pull wire 52.

[0082] In one embodiment of this application, the earthworm-like variable stiffness bionic robotic fish further includes a tail fin 7 and two pusher structures 8; the tail fin 7 is disposed at one end of the origami structure 3 away from the head 1; the two pusher structures 8 are symmetrically disposed on both sides of the tail fin 7.

[0083] like Figure 1 , Figure 2 and Figure 5 As shown, in this embodiment, pusher plate structures 8 are provided on both sides of the tail fin 7, forming a pointed receiving space between the two pusher plate structures 8, within which the tail fin 7 is located. One end of each pusher plate structure 8 is connected to the tail fin 7, and the other end is a free end. The tail fin 7 is mainly responsible for providing propulsion, while the pusher plate structures 8 on both sides of the tail fin 7 assist the tail fin 7 in jointly pushing the water flow, so that the propulsion force can be more evenly distributed, avoiding the propulsion force being too concentrated in a single direction of the tail fin 7, thereby enhancing the overall propulsion efficiency. The pusher plate structures 8 increase the pushing area of ​​the water flow and increase the hydrodynamic effect of the tail, which helps to maintain the propulsion force of the robotic fish under high speed or heavy load, especially when a large thrust is required, the pusher plate structures 8 can provide additional power support. At the same time, the two pusher plate structures 8 can help guide the water flow smoothly along the body shape of the robotic fish, avoiding the formation of unnecessary eddies or turbulence around the tail fin 7, which helps to reduce instability in hydrodynamics, making the robotic fish swim more smoothly and stably.

[0084] In relatively open water, the first pull wire 51 and the second pull wire 52, which are fixed to the rudder 42, are connected to the first fixed plate 53 and the second fixed plate 54. The swing of the servo motor 41 drives the tail fin 7 to swing to achieve propulsion. During the extension and retraction of the origami structure 3, the tail fin 7 and the push plate structure 8 can imitate the foot of an insect to push water, so that the robotic fish can propel itself forward without relying on the swing of its tail.

[0085] like Figure 1As shown, the pusher structure 8 includes a flexible connector 83, a first pusher 81, and a second pusher 82; the flexible connector 83 is connected to the tail fin 7, the first pusher 81 is disposed on the flexible connector 83, and the second pusher 82 is disposed on the flexible connector 83 and located on the side of the first pusher 81 away from the origami structure 3.

[0086] Specifically, one end of the flexible connector 83 is connected to the tail fin 7, and the other end is a free end; the first push plate 81 and the second push plate 82 are arranged side by side on the same side of the flexible connector 83. The first push plate 81 and the second push plate 82 form two independent structures and are connected by the flexible connector 83, so that the push plate structure 8 has a certain degree of flexibility, reducing the rigidity of the push plate structure 8; the pressure and direction of the water flow will change continuously during swimming, and the flexible push plate structure 8 can flexibly adjust its shape according to these changes (e.g., Figure 5 , Figure 6 and Figure 7 As shown in the diagram, this helps the robotic fish better cope with different water conditions and reduce fluid resistance. During the robotic fish's low-speed swimming or turning, the flexible push plate structure 8 helps to make smooth transitions and avoids excessive unnecessary resistance or water flow disturbance caused by the rigid push plate in these situations; the flexibility of the push plate structure 8 allows it to push water while the pull line structure 5 is moving.

[0087] The flexible connector 83 can be made of elastic materials such as silicone, which can absorb and disperse the pressure applied by the water flow, reduce the stress concentration that the first push plate 81 and the second push plate 82 may encounter, thereby improving the fatigue resistance and durability of the push plate structure 8, so that the robotic fish can maintain the stability of the water flow during different speeds or turns, reduce abrupt changes or sudden force transmission, and make the swimming process smoother and more natural.

[0088] Figure 6 and Figure 7 As shown, Figure 6 Middle arrow and Figure 7 The middle arrows all indicate the direction of the fluid (water); when the pneumatic device 2 drives the origami structure 3 to gradually extend towards the tail, the direction of the fluid acting on the pusher structure 8 is as follows: Figure 6 As shown, the angle between the two pusher structures 8 gradually increases, and the two pusher structures 8 gradually open outwards. When the pneumatic device 2 drives the origami structure 3 to gradually retract towards the head, the fluid direction of the pusher structure 8 is as follows. Figure 7 As shown, the angle between the two push plate structures 8 gradually decreases, and the two push plate structures 8 gradually close inward.

[0089] like Figure 1 and Figure 3 As shown, the push plate structure 8 also includes an elastic pad 84, which is disposed on the flexible connector 83 and located between the first push plate 81 and the second push plate 82.

[0090] The elastic pad 84 can also limit the movement of the first push plate 81 and the second push plate 82. The bonding of the elastic pad 84 to the flexible connector 83 allows the angle and shape between the first push plate 81 and the second push plate 82 to be adjusted appropriately according to changes in water flow and the movement state of the robotic fish; under different water flow conditions, the action of the push plate structure 8 can respond more flexibly, thereby improving the propulsion efficiency and stability of the robotic fish.

[0091] Meanwhile, the elastic pad 84 can effectively disperse and reduce the reaction force of the water flow on the first push plate 81 and the second push plate 82, avoiding excessive pressure and impact from the rigid push plate. The flexible design of the push plate can better alleviate and absorb the impact from the water flow, reducing the instability or loss of control of the robotic fish caused by excessive reaction force.

[0092] In summary, this invention provides a worm-like variable stiffness biomimetic robotic fish, comprising: a head; a pneumatic device disposed within the head; an origami structure with one axial end connected to the head; the pneumatic device being connected to the origami structure and used to inflate or extract air from the origami structure to drive the origami structure to extend and retract axially; a driving device disposed within the head; and a drawstring structure connected to both the driving device and the origami structure to bend the origami structure under the drive of the driving device. This application combines the origami structure with the pull-string structure. The pneumatic device inflates and deflates the origami structure, adjusting the internal pressure to achieve spatial folding and deformation, thereby adjusting the stiffness of the fish body. This allows the robotic fish to adapt to different task requirements and environmental changes. The pull-string mechanism mimics the muscle distribution of the robotic fish, pulling the fish body cavity formed by the origami structure to generate thrust through large-amplitude tail movements. In confined spaces, the coordinated movement of the origami and pull-string mechanisms produces a worm-like wriggling motion, significantly improving maneuverability in narrow spaces. Furthermore, during the extension and retraction of the origami structure, the tail fin and pusher structure mimic insect legs pushing water, allowing the robotic fish to propel itself forward without relying on tail movements.

[0093] It should be understood that the application of the present invention is not limited to the examples above. Those skilled in the art can make improvements or modifications based on the above description, and all such improvements and modifications should fall within the protection scope of the appended claims.

Claims

1. A vermicelli-like variable stiffness biomimetic robotic fish comprising a head, characterized in that, It also includes: A pneumatic device is installed inside the head; The origami structure has one axial end connected to the head; the pneumatic device is connected to the origami structure and is used to inflate or extract air from the origami structure to drive the origami structure to extend and retract axially. A drive unit is disposed within the head; A tail fin is located at the end of the origami structure opposite to the head. Two pusher plate structures are symmetrically arranged on both sides of the tail fin; the two pusher plate structures enclose a pointed receiving space, and the tail fin is located within the pointed receiving space; The pusher plate structure includes: A flexible connector is used to connect to the tail fin; The first push plate is disposed on the flexible connector; The second push plate is disposed on the flexible connector and located on the side of the first push plate away from the origami structure; The pusher structure also includes: An elastic pad is disposed on the flexible connector and located between the first push plate and the second push plate.

2. The classi worm variable stiffness biomimetic robotic fish of claim 1, wherein, The pneumatic device includes: Gas cylinder; A reversing valve is connected to the folding structure; An air pump is located between the gas storage cylinder and the reversing valve, and is connected to both the gas storage cylinder and the reversing valve.

3. The classi worm variable stiffness biomimetic robotic fish of claim 1, wherein, It also includes: A drawstring structure is connected to both the drive device and the origami structure, so as to drive the origami structure to bend under the drive of the drive device.

4. The classi worm variable stiffness biomimetic robotic fish of claim 3, wherein, The draw wire structure includes: The first pull line is located on one radial side of the origami structure, and one end of the first pull line is connected to the driving device, and the other end is connected to the origami structure. The second pull line is symmetrically arranged on the other side of the radial direction of the origami structure, and one end of the second pull line is connected to the driving device, and the other end is connected to the origami structure.

5. The classi worm variable stiffness biomimetic robotic fish of claim 4, wherein, The driving device includes: Servo motor; A rudder disc, mounted on the servo motor, is used to rotate along a horizontal plane under the drive of the servo motor. The first pull wire and the second pull wire are located on both sides of the rudder and are both connected to the rudder.

6. The classi worm variable stiffness biomimetic robotic fish of claim 4, wherein, The draw wire structure also includes: The first fixing plate is disposed on the origami structure and can reciprocate along the axial direction with the origami structure; the first pull wire and the second pull wire are located on both sides of the first fixing plate and are both connected to the first fixing plate.

7. The classi worm variable stiffness biomimetic robotic fish of claim 6, wherein, The draw wire structure also includes: The second fixing plate is disposed on the origami structure and located between the head and the first fixing plate; The second wire fixing plate is provided with a first mounting hole and a second mounting hole. The first pull wire passes through the first mounting hole and is in clearance fit with the first mounting hole; the second pull wire passes through the second mounting hole and is in clearance fit with the second mounting hole.

Images