A manta ray pectoral fin based on a hydro-soft actuator and a parameter optimization method thereof

Abstract

The application discloses a manta ray pectoral fin based on a liquid-actuated soft actuator and a parameter optimization method thereof, the manta ray pectoral fin comprising a main actuator, an auxiliary actuator and a peristaltic pump, the main actuator and the auxiliary actuator each comprising an elastic cavity and an intermediate limiting plate, the elastic cavity comprising a cylindrical cavity, the cavity being divided into upper and lower half-circular cavities by an intermediate layer; the intermediate limiting plate is a rectangular hard material plate arranged on the surface of the intermediate layer of the elastic cavity. When the main actuator and the auxiliary actuator bend in the same direction, the manta ray pectoral fin flaps upwards, the peristaltic pump draws the liquid in the upper half-circular cavity into the lower half-circular cavity, and the manta ray pectoral fin flaps downwards, and vice versa. When the main actuator and the auxiliary actuator bend in opposite directions, the manta ray pectoral fin flaps upwards, the peristaltic pump draws the liquid in the upper half-circular cavity of the main actuator into the lower half-circular cavity of the main actuator, draws the liquid in the lower half-circular cavity of the auxiliary actuator into the upper half-circular cavity of the auxiliary actuator, and the manta ray pectoral fin flaps downwards, and vice versa; the flapping direction is determined by the bending direction of the main actuator.

Description

Technical Field

[0001] This invention relates to the field of underwater biomimetic robot technology, and in particular to a manta ray-inspired pectoral fin based on a hydraulic soft actuator and a method for optimizing its parameters. Background Technology

[0002] Rigid robots are highly constrained by the external environment and lack flexibility during execution. To overcome the shortcomings of traditional robots, the research field of soft robots has developed rapidly. Compared to rigid robots, soft robots are more deformable and possess mechanical elasticity. The core of soft robots lies in their soft actuators. There are many common forms of soft actuators, among which the main actuation methods include shape memory alloys (SMA), fluid (pneumatic-hydraulic), and electroactive polymers.

[0003] Manta rays are fish that use their pectoral fins to generate propulsion. They have flattened, rhomboid bodies and excellent cruising and maneuverability, allowing them to turn nimbly on the spot. The manta ray-inspired pectoral fin structure is based on the manta ray's biological prototype, mimicking its movement characteristics. It is a biomimetic pectoral fin made using a special drive structure and flexible materials. The manta ray-inspired pectoral fin can mimic the flapping motion of a manta ray to generate propulsion.

[0004] Patent CN 112339958 A proposes a biomimetic manta ray structure driven by SMA filaments. Although its control method is simple and has low noise, the driving force generated by the SMA filaments is relatively small, making it difficult to produce large deformations. This results in the biomimetic manta ray moving slowly and with poor flexibility. In the paper "ABending Pneumatic Rubber Actuator RealizingSoft-bodied Manta Swimming Robot (doi:10.1109 / ROBOT.2007.364246)," Osaka University in Japan developed the world's first pneumatic soft manta ray by using a wire-wound actuator to drive a silicone wing membrane at the front. The biomimetic manta ray has a single pectoral fin ray, which is completely flexible, simple in structure, and easy to control. However, it can only drive the trailing edge by swinging / bending the leading edge actuator. It passively deforms in the water to generate thrust by its own flexibility and cannot actively control the pitching attitude of the pectoral fin. The propulsion efficiency is significantly different from that of the biological prototype. Summary of the Invention

[0005] Purpose of the invention: The present invention aims to provide a manta ray-inspired pectoral fin based on a hydraulic soft actuator that can actively control pitch attitude and a method for optimizing its parameters.

[0006] Technical Solution: The manta ray-inspired pectoral fin based on a hydraulic soft actuator described in this invention includes a left peristaltic pump, a right peristaltic pump, and mirror-image left and right pectoral fins. Both the left and right pectoral fins have a main actuator and an auxiliary actuator on their elastic substrates. The main and auxiliary actuators are connected to the peristaltic pumps via pipes. Each main and auxiliary actuator includes an elastic cavity and an intermediate limiting plate. The elastic cavity includes a cylindrical cavity divided into symmetrical upper and lower semicircular cavities by an intermediate layer. Each semicircular cavity has an interface connected to a pipe. The intermediate limiting plate is a rectangular rigid material plate disposed on the surface of the intermediate layer of the elastic cavity. When high-pressure fluid enters the upper semicircular cavity, the main / auxiliary actuator bends downwards; when high-pressure fluid enters the lower semicircular cavity, the main / auxiliary actuator bends upwards.

[0007] Furthermore, when the main actuator and the auxiliary actuator bend in the same direction (with a phase difference of 360°), the upper semicircular chambers of the main actuator and the auxiliary actuator form a loop one with the peristaltic pump through pipes, and the lower semicircular chambers of the main actuator and the auxiliary actuator form a loop two with the peristaltic pump through pipes. When bending upwards, the peristaltic pump draws the liquid from the upper semicircular chamber into the lower semicircular chamber, and vice versa when bending downwards.

[0008] Furthermore, when the main actuator and the auxiliary actuator bend in opposite directions (with a phase difference of 180°), the upper and lower semicircular chambers of the main actuator and the auxiliary actuator form loop three and loop four respectively with the peristaltic pump through pipes. When the actuator moves upward, the peristaltic pump draws the liquid from the upper semicircular chamber of the main actuator to the lower semicircular chamber of the main actuator, and draws the liquid from the lower semicircular chamber of the auxiliary actuator to the upper semicircular chamber of the auxiliary actuator. When the actuator moves downward, the opposite occurs. The direction of the movement is determined by the bending direction of the main actuator.

[0009] Preferably, the main actuator and the auxiliary actuator further include limiting lines, which consist of multiple side lines and two top lines. The side lines are circular and evenly distributed along the axial direction of the elastic cavity, arranged on the surface of the cavity. The top lines connect each side line in sequence and are arranged on the upper and lower surfaces of the elastic cavity. The side lines of the limiting lines restrict the radial expansion of the long cavity, while the top lines improve the overall stiffness of the fin surface.

[0010] Preferably, the limiting line is made of rigid silicone material.

[0011] Preferably, the elastic cavity is made of silicone.

[0012] Furthermore, the elastic matrix includes a first skeleton, a second skeleton, and a flexible fin surface. The first skeleton and the second skeleton are made of rigid silicone. The first skeleton is a trapezoid without bevels, with its lower long side connected to the end face of the elastic cavity of the main actuator near the peristaltic pump, and its upper short side connected to the closed end face of the elastic cavity.

[0013] Preferably, the second frame is a horizontal "J" shape, with its straight side connected to the end face of the elastic cavity of the auxiliary actuator near the peristaltic pump, and the other end of the flexible cavity of the auxiliary actuator is a hemispherical seal connected to the end face of the external pectoral fin.

[0014] Preferably, the flexible fin is made of silicone and is divided into three fin sections: the upper fin is connected between the first frame and the main actuator, the middle fin is connected between the main actuator and the auxiliary actuator, and the lower fin is connected between the second frame and the auxiliary actuator.

[0015] The parameter optimization method for the manta ray-inspired pectoral fin based on a hydraulic soft actuator described in this invention includes the following steps:

[0016] (1) Set the radius r of the semi-circular chamber that affects the elastic cavity of the main actuator. z Wall thickness t z Length L z The thickness of the first intermediate layer is t z1 ; Calculate the fluid pressure P supplied to the main actuator, the bending angle θ of the main actuator, and the relationship between pressure P and bending angle θ.

[0017]

[0018] In the formula, r is the radius of the semicircular chamber of the actuator, t1 is the wall thickness, and M... θ The combined torque of the upper and lower stresses on the outside of the main actuator;

[0019] (2) Determine the bending angle θ of the main actuator and the optimal flapping amplitude θ of the manta ray. z Relationship,

[0020] When θ≠θ z Then, by finding the maximum and minimum values, the structural parameters of the main actuator are optimized to make the bending angle of the main actuator under pressure P as close as possible to the optimal flapping amplitude θ of the manta ray. z The details are as follows:

[0021]

[0022] In the formula, a i All values ​​of i ∈ [1, 10] are positive integers;

[0023] Confirm the position of the auxiliary actuator, i.e., calculate the distance L1 between the auxiliary actuator and the main actuator:

[0024]

[0025] In the formula, N is the pectoral fin wave number. The phase difference between the primary and secondary actuators, where L is the length of the manta ray in the chordal direction;

[0026] (3) After confirming the position of the auxiliary actuator, set the radius r of the semi-circular chamber of the elastic cavity of the auxiliary actuator. f Wall thickness t f Length L f The thickness t of the second intermediate layer f1 Calculate the bending angle θ1 of the auxiliary actuator when the fluid with the same pressure P as the main actuator is introduced into the auxiliary actuator.

[0027] (4) Determine the bending angle θ1 of the auxiliary actuator and the optimal pitch angle θ of the manta ray. f Relationship, when θ1≠θ z -θ f When the maximum and minimum values ​​are obtained, the structural parameters of the auxiliary actuator are optimized by finding the maximum and minimum values, so that the angle between the auxiliary actuator and the main actuator is as close as possible to the target value under the same pressure P.

[0028] Beneficial Effects: Compared with the prior art, the significant advantages of this invention are: 1. The manta ray pectoral fin structure based on the hydraulic soft actuator described in this invention is simple. It uses silicone of different hardness to print and imitate the manta ray pectoral fin. The flexible fin surface and the cavity of the main and auxiliary actuators are made of soft silicone rubber, while the intermediate limiting plate, limiting line and skeleton are made of hard silicone rubber. It achieves simple control of the manta ray pectoral fin structure. One pectoral fin flapping only requires one peristaltic pump to control. The peristaltic pump inputs the liquid from one half of the main and auxiliary actuator cavities to the other half of the cavities, thereby realizing the bending deformation of the pectoral fin. When moving forward, two peristaltic pumps work simultaneously; when turning, only one peristaltic pump works. 2. The parameter optimization method described in this invention simplifies the complex problem of designing manta ray pectoral fins. Based on the mathematical model established for the actuator, the structural parameters of the actuator are adjusted by combining the method of finding the maximum value with the optimization model to achieve the optimal value of the manta ray swimming parameters. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the structure of the present invention;

[0030] Figure 2 A schematic diagram of the main actuator;

[0031] Figure 3 A schematic diagram of the auxiliary actuator;

[0032] Figure 4 This is a schematic diagram of the skeleton structure;

[0033] Figure 5 Schematic diagram of the working principle when the main actuator and the auxiliary actuator have a phase difference of 360°;

[0034] Figure 6 Schematic diagram of the working principle when the main actuator and the auxiliary actuator have a phase difference of 180°;

[0035] Figure 7This is a geometric model and parameter diagram of the semi-circular chamber of the actuator;

[0036] Figure 8 This is a flowchart of a method for optimizing actuator structural parameters. Detailed Implementation

[0037] The invention will now be further described with reference to the accompanying drawings.

[0038] The manta ray-inspired pectoral fin based on a hydraulic soft actuator described in this invention includes a left peristaltic pump, a right peristaltic pump, and mirror-image left and right pectoral fins. A main actuator and an auxiliary actuator are mounted on the elastic substrate of both the left and right pectoral fins. The main actuator and auxiliary actuator are connected to the peristaltic pumps via pipes. Both the main actuator and auxiliary actuator include an elastic cavity and an intermediate limiting plate. The elastic cavity includes a cylindrical cavity, which is divided into symmetrical upper and lower semicircular cavities by an intermediate layer. Each semicircular cavity has an interface connected to the pipe. The intermediate limiting plate is a rectangular rigid material plate disposed on the surface of the intermediate layer of the elastic cavity. When high-pressure fluid is injected into the upper semicircular cavity, the main / auxiliary actuator bends downwards; when high-pressure fluid is injected into the lower semicircular cavity, the main / auxiliary actuator bends upwards.

[0039] like Figure 1 As shown, the manta ray pectoral fin based on a soft actuator described in this invention includes a left pectoral fin 1 and a right pectoral fin 2, which are symmetrical and have the same structure. The left pectoral fin includes a main actuator 11, an auxiliary actuator 12, an elastic substrate 13, and a left peristaltic pump 14. The overall pectoral fin structure is 3D printed in one piece, and the overall structure imitates the basic characteristics of manta rays. The elastic substrate 13 contains three flexible fin surfaces. The uppermost flexible fin surface is a narrow trapezoid and is connected to the main actuator 11. The middle flexible fin surface is similar to a trapezoid, with the long side of the trapezoid connected to the main actuator 11 and the two short sides connected to the auxiliary actuator 12. The lowermost flexible fin surface is triangular, with the long side corresponding to the right angle of the triangle connected to the auxiliary actuator 12. The left peristaltic pump 14 has two interfaces and two connection methods. When the main actuator and auxiliary actuator bend in the same direction (phase difference of 360°), the upper semicircular chambers of the main and auxiliary actuators form loop one with the peristaltic pump through pipes, and the lower semicircular chambers of the main and auxiliary actuators form loop two with the peristaltic pump through pipes. When bending upwards, the peristaltic pump draws liquid from the upper semicircular chamber to the lower semicircular chamber; the opposite occurs when bending downwards. When the main and auxiliary actuators bend in opposite directions (phase difference of 180°), the upper and lower semicircular chambers of the main and auxiliary actuators form loop three and loop four respectively with the peristaltic pump through pipes. When bending upwards, the peristaltic pump draws liquid from the upper semicircular chamber of the main actuator to the lower semicircular chamber of the main actuator, and draws liquid from the lower semicircular chamber of the auxiliary actuator to the upper semicircular chamber of the auxiliary actuator; the opposite occurs when bending downwards. The connection between the right pectoral fin 2 and the right peristaltic pump 21 is the same as that on the left.

[0040] like Figure 2 As shown, the main actuator 11 is cylindrical in shape and includes a first interface 111, a long cavity 112, a long limiting line 113, a long intermediate limiting plate 114, and a second interface 115. Both the first interface 111 and the second interface 115 are rectangular in shape and have hollow cylinders inside. The long cavity 112 is made of silicone and is cylindrical in shape. Its internal cylindrical cavity is separated by an intermediate layer to form two semi-circular chambers, which are symmetrical along the intermediate layer. One end of the long cavity 112 is sealed, and the other end has two circular through holes, which are located at positions corresponding to the upper and lower semi-circular chambers. The upper circular through hole connects to one end of the first interface 111, meaning the first interface 111 connects to the upper semi-circular chamber of the main actuator, and the lower circular through hole connects to the second interface 115, meaning the second interface 115 connects to the lower semi-circular chamber of the main actuator. The long limiting line 113 includes multiple side lines and two top lines. The long limiting line 113 is made of rigid silicone. Each side line is circular and evenly distributed along the axial direction of the long cavity 112, arranged on the surface of the long cavity 112. The top line connects each side line from the first to the last and is arranged on the upper and lower surfaces of the long cavity 112. The side lines of the long limiting line restrict the radial expansion of the long cavity 112, while the top lines improve the overall rigidity of the fin surface. The long intermediate limiting plate 114 is made of rigid silicone and is rectangular in shape, arranged on the surface of the intermediate layer of the long cavity 112. When high-pressure fluid enters the upper semicircular chamber of the actuator, the actuator bends downward due to the non-extensibility of the long intermediate limiting layer. Similarly, when high-pressure fluid enters the lower semicircular chamber of the actuator, the actuator bends upward.

[0041] like Figure 3As shown, the auxiliary actuator 12 is cylindrical in shape and includes a third interface 125, a short cavity 122, a short spiral 123, a short intermediate limiting plate 124, and a fourth interface 121. Both the third interface 125 and the fourth interface 121 are rectangular in shape, with hollow cylinders inside. The short cavity 122 is made of silicone and is cylindrical in shape. Its internal cylindrical cavity is separated by an intermediate layer to form two semi-circular chambers, which are symmetrical along the intermediate layer. One end of the short cavity 122 is a hemispherical seal connected to the end face of the external pectoral fin, and the other end has two circular through holes, which are located at positions corresponding to the upper and lower semi-circular chambers. The upper circular through hole connects to one end of the third interface 125, meaning the third interface 125 connects to the upper semi-circular chamber of the auxiliary actuator, and the lower circular through hole connects to one end of the fourth interface 121, meaning the fourth interface 121 connects to the lower semi-circular chamber of the auxiliary actuator. The short limiting line 123 includes multiple side lines and two top lines. The short limiting line 123 is made of rigid silicone. Each side line is circular in shape and evenly distributed along the axial direction of the short cavity 122, arranged on the surface of the short cavity 122. The top lines connect each side line from the first to the last and are arranged on the upper and lower surfaces of the short cavity 122. The side lines of the short limiting line 123 restrict the radial expansion of the short cavity, while the top lines improve the overall stiffness of the fin surface. The short intermediate limiting plate 124 is made of rigid silicone, is rectangular in shape, and is arranged on the surface of the intermediate layer of the short cavity 122. When high-pressure liquid is injected into the upper semi-circular chamber of the actuator, the actuator bends downwards due to the non-expandability of the short intermediate limiting layer. Similarly, when high-pressure liquid is injected into the lower semi-circular chamber of the actuator, the actuator bends upwards.

[0042] like Figure 4 As shown, the elastic substrate 13 is triangular in shape, comprising a first skeleton 132, a second skeleton 133, and a flexible fin 131. The first skeleton 132 is made of rigid silicone and is a trapezoid without any sloping sides. Its lower long side connects to the end face of the first interface 111, and its upper short side connects to the closed end face of the long cavity 112. The second skeleton 133 is also made of rigid silicone and is a horizontal "J" shape. Its straight side connects to the end face of the fourth interface 121 of the short cavity 122. The flexible fin 131 is made of silicone and mimics the shape of a manta ray's pectoral fin. It consists of three flexible fin sections: the upper section connects the first skeleton 132 to the main actuator 11; the middle section connects the main actuator 11 to the auxiliary actuator 12; and the lower section connects the second skeleton 133 to the auxiliary actuator 12, making the overall structure resemble the shape of a manta ray.

[0043] like Figure 5As shown, when the main actuator 11 and the auxiliary actuator 12 bend in the same direction, that is, when the phase difference between the main actuator 11 and the auxiliary actuator 12 is 360°, the flapping direction depends on the bending direction of the main actuator 11. When flapping upwards, the fluid in the upper semicircular chamber of the main actuator 11 and the auxiliary actuator 12 is drawn into the lower semicircular chamber of the main actuator 11 and the auxiliary actuator 12 through the left peristaltic pump 14, and the right pectoral fin 2 is the same as the left pectoral fin 1. Similarly, when flapping downwards, the fluid in the lower semicircular chamber of the main actuator 11 and the auxiliary actuator 12 is drawn into the upper semicircular chamber of the main actuator 11 and the auxiliary actuator 12 through the left peristaltic pump 14, and the right pectoral fin 2 is the same as the left pectoral fin 1. When moving forward, both pectoral fins need to flap simultaneously, that is, both peristaltic pumps operate simultaneously. When turning, only one pectoral fin needs to flap, that is, only one peristaltic pump needs to operate.

[0044] like Figure 6 As shown, when the main actuator 11 and the auxiliary actuator 12 bend in opposite directions, that is, when the phase difference between the main actuator 11 and the auxiliary actuator 12 is 180°, the flapping direction depends on the bending direction of the main actuator 11. When flapping upwards, the fluid from the upper semicircular chamber of the main actuator 11 and the lower semicircular chamber of the auxiliary actuator 12 is drawn into the lower semicircular chamber of the main actuator 11 and the upper semicircular chamber of the auxiliary actuator 12 through the left peristaltic pump 14. The right pectoral fin 2 is the same as the left pectoral fin 1. Similarly, when flapping downwards, the fluid from the lower semicircular chamber of the main actuator 11 and the upper semicircular chamber of the auxiliary actuator 12 is drawn into the upper semicircular chamber of the main actuator 11 and the lower semicircular chamber of the auxiliary actuator 12 through the left peristaltic pump 14. The right pectoral fin 2 is the same as the left pectoral fin 1. When moving forward, both pectoral fins need to flap simultaneously, meaning both peristaltic pumps are operating at the same time. When turning, only one pectoral fin needs to flap, meaning only one peristaltic pump is operating.

[0045] like Figure 7 and Figure 8 As shown, the method for optimizing the structural parameters of the manta ray-inspired pectoral fin based on a soft actuator according to the present invention includes the following steps:

[0046] (1) Set the parameters that affect the main actuator: the radius r of the semi-circular chamber in the long cavity 112 z Wall thickness t z Long cavity length L z and the thickness t of the intermediate layer of the long cavity 112 z1 ;

[0047] The mathematical relationship between the actuator pressure P and the bending angle θ is as follows:

[0048]

[0049] In the formula, r is the radius of the semicircular chamber of the actuator, t1 is the wall thickness, and M... θThis is the combined torque of the upper and lower layer stresses on the actuator's exterior. Increased length, larger radius, reduced wall thickness, and reduced intermediate layer thickness facilitate bending of the actuator at lower air pressures.

[0050] (2) Introduce fluid at a pressure of P1 into the main actuator and calculate the bending angle θ1 of the main actuator.

[0051] (3) Compare the calculated bending angle θ1 of the main actuator with the optimal flapping amplitude of the manta ray, 60°, that is, with the bending angle of the main actuator, to determine whether θ1 is equal to 60°.

[0052] (4) When the bending angle θ1 ≠ 60°, the structural parameters of the main actuator are optimized by finding the maximum and minimum values, and an optimization model is established. Through optimization, the bending angle of the main actuator is made as close as possible to the target value under the same pressure P1.

[0053] In the formula, a i ,i∈[1,10] are all positive integers, a i ∈[1,5],i∈[1,4]∪[7,8],a i ∈[80,200], i∈[5,6], a i ∈[10,60],i∈[9,10], where r is the radius of the semicircular chamber of the actuator, t is the wall thickness, L is the length of the actuator cavity, and t2 is the thickness of the intermediate layer.

[0054] When the main actuator bends at an angle θ1 = 60° under pressure P1, the position of the auxiliary actuator is determined, i.e., the distance L1 between the auxiliary actuator (5) and the main actuator. This is determined using the formula...

[0055] Confirm the distance between the auxiliary actuator and the main actuator. Here, N represents the pectoral fin wave number. The phase difference between the two actuators is L, which is the length of the manta ray in the chord direction. In this embodiment, the pectoral fin wavenumber N is 1, and the phase difference is... or Corresponding to or

[0056] (6) After confirming the position of the auxiliary actuator, set the radius r of the semi-circular chamber in the short cavity 122, which affects the auxiliary actuator. f Wall thickness t f Short cavity length L f and the thickness t of the intermediate layer of short cavity 122 f1 M θThis is the combined torque of the upper and lower layer stresses on the actuator's exterior. Increased length, larger radius, reduced wall thickness, and reduced intermediate layer thickness facilitate bending of the actuator at lower air pressures.

[0057] (7) Calculate the fluid pressure P1 that is the same as that of the main actuator when it is introduced into the auxiliary actuator according to formula (1), and calculate the bending angle θ2 of the auxiliary actuator.

[0058] (8) The calculated bending angle θ2 is compared with the optimal pitch angle θ of the manta ray. f That is, the angle θ between the auxiliary actuator and the main actuator under pressure P. f Compare and determine whether θ2 equals θ. z -θ f The optimal pitch angle when the phase difference is 360° is 40°, which means the angle between the two actuators is 40°. Determine if the bending angle θ2 equals 20°. The optimal pitch angle when the phase difference is 180° is 80°, which means the angle between the two actuators is 80°. Determine if the bending angle θ2 equals -20°.

[0059] (9) When the bending angle θ2≠θ z -θ f In this case, the structural parameters of the main actuator are optimized by finding the maximum and minimum values, and an optimization model is established. Through optimization, the angle between the auxiliary actuator and the main actuator is made as close as possible to the target value under the same pressure P1.

[0060] In the formula, a i ,i∈[1,10] are all positive integers, a i ∈[1,5],i∈[1,4]∪[7,8],a i ∈[40,80], i∈[5,6], a i ∈[10,60],i∈[9,10], where r is the radius of the semicircular chamber of the actuator, t is the wall thickness, L is the length of the actuator cavity, and t2 is the thickness of the intermediate layer.

[0061] (10) When the bending angle θ2 is equal to θ z -θ f When the difference is minimized, the structural parameter optimization is complete.

[0062] like Figure 7 As shown, L is the arc length, r is the radius of the semicircular cavity; t is the wall thickness; t1 is the thickness of the intermediate layer; R is the radius of curvature; θ is the bending angle; S t For top layer stress; S b For the underlying stress; M a M is the bending moment exerted by the pressure inside the cavity on the actuator end; θ For the upper and lower layers of the actuator exterior stress St and S b The combined torque; The angle between a point on the upper surface of the semicircular cavity and the bottom surface.

Claims

1. A method for optimizing the parameters of a manta ray-inspired pectoral fin based on a hydraulic soft actuator, characterized in that, The manta ray-like pectoral fins include a left peristaltic pump (14), a right peristaltic pump (21), and mirror-image left and right pectoral fins (1 and 2). The elastic substrates (13) of the left and right pectoral fins (1 and 2) are provided with a main actuator (11) and an auxiliary actuator (12). The main actuator and the auxiliary actuator are connected to the peristaltic pumps through pipes (3). The main actuator (11) and the auxiliary actuator (12) both include an elastic cavity and an intermediate limiting plate. The elastic cavity includes a cylindrical cavity, which is divided into symmetrical upper and lower semi-circular cavities by an intermediate layer. Each semi-circular cavity is provided with an interface connected to the pipe (3). The intermediate limiting plate is a rectangular rigid material plate and is set on the surface of the intermediate layer of the elastic cavity. When the upper semi-circular cavity is filled with high-pressure fluid, the main / auxiliary actuator bends downward. When the lower semi-circular cavity is filled with high-pressure fluid, the main / auxiliary actuator bends upward. The parameter optimization method includes the following steps: (1) Set the radius of the semi-circular chamber that affects the elastic cavity of the main actuator. Wall thickness ,length First intermediate layer thickness ; Calculate the fluid pressure P supplied to the main actuator, and the bending angle of the main actuator. Pressure P and bending angle The relationship is ， In the formula, r is the radius of the semi-circular chamber of the actuator. For wall thickness, The combined torque of the upper and lower stresses on the outside of the main actuator; (2) Determine the bending angle of the main actuator With the optimal flapping amplitude of manta rays Relationship, when Then, by finding the maximum and minimum values, the structural parameters of the main actuator are optimized to make the bending angle of the main actuator under pressure P as close as possible to the optimal flapping amplitude of the manta ray. The details are as follows: In the formula, All are positive integers; Confirm the position of the auxiliary actuator, i.e., calculate the distance between the auxiliary actuator and the main actuator. : In the formula, N is the pectoral fin wave number. The phase difference between the primary and secondary actuators, where L is the length of the manta ray in the chordal direction; (3) After confirming the position of the auxiliary actuator, set the radius of the semi-circular chamber of the elastic cavity of the auxiliary actuator. Wall thickness ,length Second intermediate layer thickness Calculate the bending angle of the auxiliary actuator when a fluid with the same pressure P as the main actuator is introduced into the auxiliary actuator. ; (4) Determine the bending angle of the auxiliary actuator Optimal pitch angle with manta rays Relationship, when Then, the structural parameters of the auxiliary actuator are optimized by finding the maximum and minimum values, so that the angle between the auxiliary actuator and the main actuator is as close as possible to the target value under the same pressure P. Then the optimization is complete.

2. The parameter optimization method for manta ray-inspired pectoral fins based on hydraulic soft actuators according to claim 1, characterized in that, When the main actuator and the auxiliary actuator bend in the same direction, the upper semicircular chambers of the main actuator and the auxiliary actuator form a circuit one with the peristaltic pump through pipes, and the lower semicircular chambers of the main actuator and the auxiliary actuator form a circuit two with the peristaltic pump through pipes. When bending upwards, the peristaltic pump draws the liquid from the upper semicircular chamber to the lower semicircular chamber, and vice versa when bending downwards.

3. The parameter optimization method for the manta ray-inspired pectoral fin based on a hydraulic soft actuator according to claim 1, characterized in that, When the main actuator and the auxiliary actuator bend in opposite directions, the upper and lower semicircular chambers of the main actuator and the auxiliary actuator form circuit three and circuit four respectively with the peristaltic pump through pipes. When the actuator moves upward, the peristaltic pump draws the liquid from the upper semicircular chamber of the main actuator to the lower semicircular chamber of the main actuator, and draws the liquid from the lower semicircular chamber of the auxiliary actuator to the upper semicircular chamber of the auxiliary actuator. When the actuator moves downward, the opposite occurs. The direction of the movement is determined by the bending direction of the main actuator.

4. The parameter optimization method for the manta ray pectoral fin based on a hydraulic soft actuator according to claim 1, characterized in that, The main actuator (11) and the auxiliary actuator (12) also include limiting lines. The limiting lines consist of multiple side lines and two top lines. The side lines are circular and are evenly distributed along the axial direction of the elastic cavity and arranged on the surface of the cavity. The top lines connect each side line in sequence and are arranged on the upper and lower surfaces of the elastic cavity.

5. The parameter optimization method for manta ray pectoral fins based on hydraulic soft actuators according to claim 4, characterized in that, The limiting line is made of rigid silicone material.

6. The parameter optimization method for the manta ray-inspired pectoral fin based on a hydraulic soft actuator according to claim 1, characterized in that, The elastic cavity is made of silicone.

7. The parameter optimization method for the manta ray-inspired pectoral fin based on a hydraulic soft actuator according to claim 1, characterized in that, The elastic matrix includes a first skeleton, a second skeleton, and a flexible fin surface. The first skeleton and the second skeleton are made of rigid silicone. The first skeleton is a trapezoid without a slanted side. Its lower long side is connected to the end face of the elastic cavity of the main actuator (11) near the peristaltic pump, and its upper short side is connected to the closed end face of the elastic cavity.

8. The parameter optimization method for the manta ray-inspired pectoral fin based on a hydraulic soft actuator according to claim 7, characterized in that, The second frame is a horizontal "J" shape, with its straight side connected to the end face of the elastic cavity of the auxiliary actuator (12) near the peristaltic pump. The other end of the flexible cavity of the auxiliary actuator (12) is a hemispherical seal connected to the end face of the external pectoral fin.

9. The parameter optimization method for manta ray-inspired pectoral fins based on hydraulic soft actuators according to claim 8, characterized in that, The flexible fin is made of silicone and is divided into three sections: the upper fin connects the first frame and the main actuator, the middle fin connects the main actuator and the auxiliary actuator, and the lower fin connects the second frame and the auxiliary actuator.

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