Bionic Drag Reduction Fairing Design Method and Device for Amphibious Cross-Domain Robots

Abstract

The present invention provides a bionic drag reduction fairing design method and device for a land-water cross-domain robot, belonging to the field of cross-domain robots. First, a marine organism is selected as the bionic object according to the structural characteristics of the land-water cross-domain robot, morphological analysis is carried out on the selected bionic object, and the contour of the corresponding part of the bionic object is extracted. Then, parametric modeling is carried out on the extracted external contour, including parametric modeling of the bionic head wing part, bionic pectoral fin, and bionic tail. Then, based on the parametric models of each part, physical models of the head wing part, pectoral fin part, and tail are designed respectively. Finally, the physical model designs of each part are integrated to obtain an overall bionic fairing model. The fairing of the present invention can cover the thruster and part of the crawler of the robot, streamline the shape of the tracked amphibious robot, greatly reduce the resistance of the tracked cross-domain robot when traveling on land and in water, and enhance the ability of the land-water cross-domain robot to complete underwater tasks.

Description

Technical Field

[0001] The present invention belongs to the field of amphibious robots, and more specifically, relates to a design method and device for a bionic drag reduction fairing applied to a water-land cross-domain robot. Background Art

[0002] The tracked-propeller compound cross-domain robot has strong mobility. The water-land cross-domain robot can adjust its motion mode according to the changes in water and land driving environments. It not only has the ability to move on land and in water, but can also travel in the transition interval between land and water areas. It has received extensive attention because it can pass through complex road conditions. The tracked-propeller compound cross-domain robot has a surface contact with the ground, a large contact area, strong adhesion, strong mobility, and strong obstacle-crossing ability, and has strong driving ability in the wild and complex environments. However, the speed of the tracked cross-domain robot is slow. Limited by the main dimensions and the body lines, its anti-resistance performance is poor. When underwater, affected by the frictional resistance and pressure difference resistance brought by the blockage of the water flow, the traveling speed and the traveling speed of the tracked cross-domain robot are very limited, and the energy consumption is large. According to theoretical calculations, under the condition that the energy and power are certain, when the resistance is reduced by 10%, the underwater driving speed and driving mileage of the water-land cross-domain robot can be increased by 3.57%. Thus, it can be seen that reducing the underwater navigation resistance of the cross-domain robot can effectively reduce the energy consumption of the robot, increase the navigation speed and navigation mileage of the robot, increase the continuous operation time of the water-land cross-domain, and enhance the ability of the water-land cross-domain robot to complete underwater tasks. Therefore, it is of great significance to study the drag reduction of the water-land cross-domain robot.

[0003] The publication number CN201512016U discloses a design of a footplate-type amphibious robot. This robot has relatively high flexibility on land, but lacks a drag reduction shape design for traveling in water, resulting in a relatively large resistance when the robot travels in water, and its operation in water is extremely limited. The publication number CN113619759A proposes a relatively simple underwater bionic drag reduction design for an amphibious robot, but this design is limited to amphibious robots driven by oscillating fins and is not applicable to tracked amphibious unmanned vehicles.

[0004] Therefore, it is of great significance to design a new type of bionic drag reduction fairing applied to water-land cross-domain robots. Summary of the Invention

[0005] Aiming at the defects of the prior art, the present invention provides a design method and device for a bionic drag reduction fairing applied to a water-land cross-domain robot. By imitating the shape of marine organisms, a fairing is designed to solve the problems of large resistance and small speed when the existing cross-domain robot sails.

[0006] According to one aspect of the present invention, a bionic drag reduction fairing design method for a water-land cross-domain robot is provided. First, a marine organism is selected as the bionic object based on the structural characteristics of the water-land cross-domain robot. Morphological analysis is carried out on the selected bionic object, and the contour of the corresponding part of the bionic object is extracted.

[0007] Next, parametric modeling is carried out on the extracted outer contour. The outer contour is divided into a head wing part, a pectoral fin part, and a tail part. The parametric modeling includes three parts, namely parametric modeling of the head wing part, parametric modeling of the pectoral fin, and parametric modeling of the tail part, to obtain the parametric models of each part.

[0008] Then, based on the parametric models of each part and according to the functions and actual working conditions required by the head wing part, the pectoral fin part, and the tail part respectively, the actual parameters of each part are determined, and the physical model designs of the head wing part, the pectoral fin part, and the tail part are carried out respectively.

[0009] Finally, the physical model designs of each part are integrated to obtain the overall bionic fairing model.

[0010] Further, a hammerhead shark is selected as the bionic object.

[0011] Further, when carrying out parametric modeling of the head wing part, the outer contour of the hammerhead shark's head is decomposed into a sine curve along the horizontal direction and an elliptical curve along the horizontal direction for parametric modeling to obtain the parametric model of the head wing part contour. The sine curve along the horizontal direction is composed of three sine functions with different amplitudes connected. The equation of the sine curve along the horizontal direction is as follows:

[0012]

[0013] Among them, the meanings of the parameters are: A1, A2, and A3 are the three different amplitudes of the sine curve, λ1, λ2, and λ3 are the three periods of the sine curve, w_length is the average period, T is the time, x is the abscissa, and y is the ordinate.

[0014] Further, the equation of the elliptical curve along the horizontal direction is:

[0015]

[0016] Among them, the meanings of the parameters are: a is the major axis of the ellipse, and b is the minor axis of the ellipse.

[0017] Further, the curve equation of the outer contour of the hammerhead shark's head is as follows:

[0018]

[0019] Further, when parametric modeling of the pectoral fin is performed, the pectoral fin part structure consists of two parts: a parabola curve equation and a circle equation. The outer contour of the pectoral fin part is parametrically modeled using the parabola curve equation, and the central through-hole on the pectoral fin part is parametrically modeled using the circle equation.

[0020] Specifically, first determine the axis of symmetry of the parabola, then set the vertex of the parabola y3 as (0, k), and based on the vertex form, set the parabola equation y = ax^ 2 + k, and establish the outer contour model, where a is the coefficient of the parabola equation.

[0021] Next, set the center coordinates of the circle (0, y1), and its position is determined according to the layout of the rear thrusters of the amphibious cross-domain robot. Determine the radius R1 of the circle according to the overall size of the rear thrusters. Based on the circle equation x^ 2 +(y - y1)^ 2 = R1^ 2 Establish the contour model of the central through-hole.

[0022] Among them, the meanings of each parameter are: y1 is the ordinate of the center of the circle, x is the abscissa, y is the ordinate, and R1 is the radius.

[0023] Further, when parametric modeling of the tail is performed, according to the shape of the hammerhead shark's tail, the tail contour is simplified into a rectangular outer contour and a quadratic curve-shaped concave tail end. The tail model consists of two parts: a rectangular equation and a quadratic curve equation.

[0024] First, determine the axis of symmetry of the quadratic curve equation, then set the vertex of the quadratic curve equation as (0, k4), and based on the quadratic curve equation Ax^ 2 + Bxy + Cy^ 2 + Dx + Ey + F = 0 to establish the central contour model. Next, set the length m of the rectangle, and then set the width n of the rectangle, and establish the parametric model of the tail based on the rectangular equation. Among them, the meanings of each parameter are: A, B, C, D, E, F are the coefficients of the quadratic curve equation, x is the abscissa, and y is the ordinate.

[0025] According to the second aspect of the present invention, there is also provided a bionic drag reduction fairing designed and obtained by the method as described above.

[0026] Further, round holes are distributed on the top surfaces of both sides of the head wing part of the fairing. The round holes cover the thrusters at both front ends of the amphibious cross-domain robot. The side avoidance surfaces on both sides of the head wing are hammer-shaped, and their cross-sections gradually decrease from the middle to the front and rear ends. A convex arc surface is designed on the lower side of the front end of the head wing part, and the inner side of the convex arc surface covers the left and right tracks of the amphibious cross-domain robot.

[0027] Further, the pectoral fin imitation of the fairing has pectoral fin round holes, which are distributed on both sides and cover the thrusters on both sides of the rear end of the amphibious cross-domain robot. The pectoral fin round holes are through holes, and the connecting part between the side of the pectoral fin and the upper shell is a smooth transition surface. The profiles of the two side walls of the tail imitation of the fairing are arc-shaped designs. The top surface of the middle upper part of the tail imitation of the fairing is an arc-shaped concave downward. The tail imitation of the fairing extends successively and has a rear extension part similar to the shape of a fish tail.

[0028] Generally speaking, compared with the prior art, the above technical solution conceived by the present invention has the following

[0029] Beneficial effects:

[0030] By studying the microscopic structures of the head, pectoral fins, and tail of the hammerhead shark, the present invention proposes a parametric modeling method. On this basis, combined with the actual working conditions and the functions to be achieved, a physical model is further designed, providing an important reference for the drag reduction design of the amphibious cross-domain robot with underwater navigation function. The present invention proposes a bionic fairing based on the shape of the hammerhead shark for the amphibious cross-domain robot, which solves the problem of large underwater navigation resistance while ensuring the mobility of the tracked-propeller composite cross-domain robot, and significantly reduces the energy consumption of the amphibious cross-domain robot during underwater navigation. Description of the Drawings

[0031] Figure 1 is the overall flow chart of the bionic fairing design method provided by the embodiment of the present invention;

[0032] Figure 2 is the design schematic diagram of the head imitation wing part in the embodiment of the present invention;

[0033] Figure 3 is the schematic diagram of extracting the head contour of the hammerhead shark in the embodiment of the present invention;

[0034] Figure 4 is the schematic diagram of parametric modeling of the head imitation wing part in the embodiment of the present invention;

[0035] Figure 5a is the schematic diagram of the X-axis curve of parametric modeling of the head imitation wing part in the embodiment of the present invention;

[0036] Figure 5b is the schematic diagram of the Y-axis curve of parametric modeling of the head imitation wing part in the embodiment of the present invention;

[0037] Figure 6 is the schematic diagram of parametric modeling of the side structure of the hammerhead shark in the embodiment of the present invention;

[0038] Figure 7a is the top view of the head imitation wing part structure in the embodiment of the present invention;

[0039] Figure 7bIt is a three-dimensional schematic diagram of the head-like wing structure in the embodiment of the present invention;

[0040] Figure 8 It is a flowchart of the design method of the chest fin-like structure in the embodiment of the present invention;

[0041] Figure 9 It is a schematic diagram of the parametric model of the chest fin-like part in the embodiment of the present invention;

[0042] Figure 10a It is a top view of the schematic diagram of the chest fin-like structure in the embodiment of the present invention;

[0043] Figure 10b It is a three-dimensional schematic diagram of the chest fin-like part in the embodiment of the present invention;

[0044] Figure 11 It is a schematic flowchart of the design of the tail-like structure in the embodiment of the present invention;

[0045] Figure 12 It is a schematic diagram of the parametric model of the tail-like structure in the embodiment of the present invention;

[0046] Figure 13a It is a top view of the tail-like structure in the embodiment of the present invention;

[0047] Figure 13b It is a side view of the tail-like structure in the embodiment of the present invention;

[0048] Figure 14 It is a schematic diagram of the overall structure of the water-land cross-domain robot with a fairing installed in the embodiment of the present invention;

[0049] Figure 15 It is an exploded side view of the water-land cross-domain robot with a fairing installed in the embodiment of the present invention;

[0050] Figure 16 It is an exploded diagram of the water-land cross-domain robot before loading the fairing in the embodiment of the present invention;

[0051] Figure 17 It is an exploded diagram of the water-land cross-domain robot after installing the fairing in the embodiment of the present invention.

[0052] In all the figures, the same reference numerals are used to denote the same elements or structures, where: the fairing head-wing part 101, the fairing middle-front part 102, the fairing pectoral-fin part 103, the fairing tail part 104, the right front thruster 201, the right front thruster connecting rod 202, the left front thruster 203, the left front thruster connecting rod 204, the right rear thruster 205, the right rear thruster connecting rod 206, the left rear thruster 207, the left rear thruster connecting rod 208, the fairing head-wing part right connecting rod 209, the fairing head-wing part left connecting rod 210, the fairing middle-front part connecting rod 211, the fairing pectoral-fin part connecting rod 212, the fairing tail part right connecting rod 213, the fairing tail part left connecting rod 214, the rear right thruster 215, the rear right thruster connecting rod 216, the rear left thruster 217, the rear left thruster connecting rod 218, the right crawler belt 301, the left crawler belt 302. Detailed implementation manner

[0053] In order to make the objectives, technical solutions and advantages of the present invention clearer and more understandable, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0054] Figure 1 is the overall flowchart of the bionic fairing design method provided by the embodiment of the present invention. As Figure 1 shown, the overall process of the bionic fairing design method of the present invention is to select a bionic object according to the structural characteristics of the crawler-propeller compound cross-domain robot, analyze the selected bionic object based on the morphological principle, extract the contour of the corresponding part of the bionic object based on the bionics principle, perform parametric modeling on the extracted external contour, divide the external contour into a head-wing part, a pectoral-fin part and a tail part. The parametric modeling includes three parts, namely the parametric modeling of the head-wing imitation part, the parametric modeling of the pectoral-fin imitation part, and the parametric modeling of the tail imitation part, obtain the parametric models of each part, and based on the parametric models of each part, and according to the functions and actual working conditions that the head-wing part, the pectoral-fin part and the tail part need to have respectively, determine the actual parameters of each part, perform the physical model design of the head-wing part, the pectoral-fin part and the tail part respectively, and integrate the physical model designs of each part to obtain the overall bionic fairing model.

[0055] Figure 2 is the schematic diagram of the head-wing imitation part model design in the embodiment of the present invention. As Figure 2 shown, the overall process of the parametric modeling of the head-wing imitation part includes: first, determine the length parameter according to the spacing of the front-end two-side propulsion, and determine the amplitude parameters A1, A2, A3, determine the short-axis parameter A4, and obtain the top-view contour model based on the sine-ellipse fusion equation. Secondly, determine the long-axis parameter and short-axis length of the side view, and establish a parametric model based on the ellipse equation.

[0056] Figure 3 is a schematic diagram of the extraction of the hammerhead shark's head contour in an embodiment of the present invention. As Figure 3 shown, by observing the head part of the hammerhead shark and extracting the contour of the hammerhead shark's head structure, it is found that there are grooves with different amplitudes distributed on the head of the hammerhead shark, and the head grooves are distributed along an arc. Therefore, in the present invention, the outer contour of the hammerhead shark's head is decomposed into a sine curve along the horizontal direction and an elliptical curve along the horizontal direction, and parametric modeling is performed to obtain a parametric model of the head wing contour. Among them, the sine curve is composed of three sine functions with different amplitudes. Since the amphibious cross-domain robot in the present invention application has a symmetric structure, parametric modeling only studies the function distribution on one side of the symmetry. Figure 4 is a schematic diagram of parametric modeling of the imitated head wing in an embodiment of the present invention. From Figure 4 it can be seen that the periods of the three sine curves are set to three different parameters λ1, λ2, and λ3, and the amplitudes of the sine curves are set to three different variable parameters A1, A2, and A3. Half of the distance between the edges of the two thrusters is set as the major axis of the ellipse. Due to structural and space constraints, the distance between the thrusters is a known fixed value, and the minor axis of the ellipse is set as A4.

[0057] The equation of the sine curve is as follows:

[0058]

[0059] The ellipse equation is as follows:

[0060]

[0061]

[0062] The parameter definitions are as follows:

[0063] w_length = a b = A4 λ1 = λ2 = λ3

[0064] The equation of the edge contour curve of the imitated hammerhead shark fairing is as follows, and substituting the above parameters gives:

[0065]

[0066] Figure 5a is a schematic diagram of the X-axis curve of parametric modeling of the imitated head wing in an embodiment of the present invention. Figure 5b is a schematic diagram of the Y-axis curve of parametric modeling of the imitated head wing in an embodiment of the present invention. Figure 5b The curve represented is the synthesized imitated hammerhead shark curve. The hammerhead shark curve equation is as shown in formula 5 above. Figure 6It is a schematic diagram of parametric modeling of the side structure of a hammerhead shark in an embodiment of the present invention. As can be seen from the figure, the side profile of the hammerhead shark's head is similar to an ellipse. The present invention also conducts a parametric modeling process. It can be seen that the side profile of the hammerhead shark's head is similar to an ellipse. Based on the side profile, a parametric equation is established. Since the coordinate axes have a certain offset relative to the standard orthogonal axes, the coordinate axis transformation is performed according to the following formula:

[0067]

[0068]

[0069] In the formula, x and y represent the original coordinates, and x' and y' represent the transformed coordinates. Substituting the transformed coordinates into Equation (3), the side profile line can be obtained.

[0070] Figure 7a It is a top view of the head-wing-like structure in an embodiment of the present invention. Figure 7b It is a three-dimensional schematic diagram of the head-wing-like structure in an embodiment of the present invention. As can be seen from the figure, in the head-wing structure of the fairing, 1011 are round holes, which are distributed on both sides and cover the thrusters at both ends of the front side. In the head-wing structure, 1013 is a hammer-shaped design, and the cross-section gradually decreases from the middle to both ends. This design effectively avoids the direct impact of the fluid and the thruster cross-section when the cross-domain robot moves underwater. The hammer-shaped structure reduces the fluid retention around the front thruster and can significantly increase the flow velocity of the fluid passing around the thruster, thereby effectively reducing the resistance. In the head-wing structure, 1012 is an uneven edge with different amplitudes and periods. Due to the influence of the uneven edge, when the cross-domain robot sails underwater, there is a pair of counter-rotating flow vortices on both sides of the protrusion in the fluid, and they slip into the concave valley in the flow direction. This design can effectively delay the flow separation. At the front-end design of the head-wing structure, 1014 is a convex arc surface, and the inner side of the convex arc surface is marked as 1015. The inner side 1015 of the convex arc surface covers the left and right tracks. Compared with the track structure, this design can reduce the sudden change of curvature at the front side, avoid the sudden separation of the front fluid, reduce the retention area of the fluid near both sides of the track, and increase the fluid velocity to reduce the pressure drag.

[0071] The design process of the chest fin-like structure is as follows:

[0072] Figure 8 It is a schematic diagram of the parametric modeling process of the chest fin-like structure in an embodiment of the present invention. Figure 9 It is a parametric schematic diagram of the chest fin in an embodiment of the present invention. By observing the chest fin structure of the hammerhead shark, it is found that its outer contour is similar to a parabola. Therefore, the chest fin-like structure of the fairing consists of two parts: a parabola curve equation and a circle equation. Specifically, first determine the axis of symmetry of the parabola, and then set the vertex of the parabola y3 to (0, k). Based on the vertex form, set the parabola equation y = ax^ 2+k to establish the outer contour model. Secondly, set the center coordinates of the circle (0, y1), whose position is determined according to the layout of the rear thrusters. Determine the radius R1 of the circle according to the overall size of the thrusters. Based on the circle equation x^ 2 +(y - y1)^ 2 = R1^ 2 to establish the center contour model. After obtaining the above parametric model, determine the design parameters according to the actual tasks and working conditions, and further conduct the physical model design to obtain the pectoral fin-like structure.

[0073] Figure 10a - 10b is the schematic diagram of the pectoral fin-like structure in the embodiment of the present invention. As can be seen from the figure, in the fairing pectoral fin-like structure, 1031 are the pectoral fin round holes, which are distributed on both sides and cover the thrusters at both sides of the rear end. The through holes that penetrate up and down in the pectoral fin round holes can ensure the water intake and discharge of the vertical thrusters. 1032 is the connecting part between the side of the pectoral fin and the upper shell, which is a smooth transition surface. This design effectively avoids the direct impact of the fluid on the thrusters at both sides of the rear end when the cross-domain robot moves underwater. The fluid flows backward along the shell through the head fairing structure, avoiding the retention of the front-end fluid on both sides of the thrusters. The fairing structures of the head wing and the pectoral fin can significantly increase the flow velocity of the fluid passing through the surface of the robot. According to Bernoulli's law, the higher the fluid flow velocity, the lower the pressure at its corresponding position. This design can reduce the pressure difference resistance of the robot and thus significantly reduce the overall resistance.

[0074] The specific process of the design of the tail-like structure is as follows:

[0075] Figure 11 is the schematic diagram of the design flow of the tail-like model in the embodiment of the present invention. Figure 12 is the schematic diagram of the tail parametric model in the embodiment of the present invention. Combining the two figures, it can be seen that the tail contour is simplified into a rectangular outer contour and a quadratic curve model. The tail model consists of two parts: the rectangular equation and the quadratic curve equation. First, determine the symmetry axis of the quadratic curve equation, and then set the vertex of the quadratic curve equation as (0, k4). Based on the quadratic curve equation Ax^ 2 + Bxy + Cy^ 2 + Dx + Ey + F = 0 to establish the center contour model. Secondly, set the length m of the rectangle, and then set the width n of the rectangle. Establish the model based on the rectangular equation. After obtaining the above parametric model, determine the design parameters according to the actual tasks and working conditions, and further establish the model on this basis to obtain the tail-like structure model.

[0076] Figure 13a is the top view of the schematic diagram of the tail-like structure in the embodiment of the present invention. Figure 13bIt is a side view of the schematic diagram of the imitation tail structure in the embodiment of the present invention. Combining the two figures, it can be seen that the imitation tail structure of the fairing has an arc design 1041. When the cross-domain robot moves back and forth underwater, a large amount of irregularly moving fluid is generated when the first horizontal thruster 215 and the second horizontal thruster 217 rotate. At the same time, there is a large amount of fluid from the front at the bottom of the cross-domain robot. These fluids are mixed together to generate a large number of vortices, resulting in energy loss and increased resistance. Setting the bottom of the imitation tail structure of the fairing as the arc design 1041 can guide the bottom fluid to flow along the wall surface, thereby reducing the retention of fluid under the tail. The upper end 1042 of the imitation tail structure of the fairing is an arc with a gradually decreasing cross-sectional area. This design can guide the fluid at the upper end of the robot shell to flow along the wall surface, and can reduce the flow separation of the upper-end fluid at the tail. Flow separation will cause energy loss and increase the movement resistance. This design can effectively avoid flow separation, thereby reducing the movement resistance. The end of the imitation tail structure of the fairing is a rearward extension 1043 similar to the shape of a fish tail. This design can increase the stability of the cross-domain robot when disturbed by waves, and also has a guiding function. The middle arc curve is beneficial to the lightweight of the structure.

[0077] Figure 14 Shows the external shape of the amphibious cross-domain robot after installing the imitation hammerhead shark fairing. Figure 15 It is a rear side view of the exploded fairing of the amphibious cross-domain robot provided by the embodiment of the present invention. Combining the two figures, it can be seen that through the cooperation of the imitation head wing part 101, the middle and front part 102 of the fairing, the imitation pectoral fin part 103 of the fairing, and the imitation tail part 104, they jointly form the overall structure of the fairing. This fairing can cover the 4 thrusters on the upper side and the crawlers on both sides of the front part, and can prevent the fluid from forming retention around the above structures when the robot sails underwater. The arc-shaped protrusion at the front end of the fairing can prevent the sudden separation at the front end, and guide the large amount of fluid that was originally retained at the front end to the upper end of the shell and the bottom of the robot. The fluid at the upper end flows along the shell wall towards the tail. Due to the arc-shaped structure of the overall fairing, the fluid flow velocity is uniform and there will be no retention during the backward flow. The fluid flowing to the rear end will not cause flow separation due to the guidance of the tail structure, which can effectively reduce the momentum loss and the resistance of the robot when sailing underwater.

[0078] Figure 16 It is an exploded schematic diagram of the amphibious cross-domain robot before loading the fairing provided by the embodiment of the present invention. Figure 17 It is an exploded schematic diagram of the amphibious cross-domain robot after installing the fairing provided by the embodiment of the present invention. It can be seen from the two figures. Figure 16 and Figure 17Collectively show the installation relationship between the hammerhead shark-inspired fairing and related components and the tracked amphibious robot. The component connection relationships include: the head wing part 101 of the fairing is connected to the cross-domain robot through the right connecting rod 209 of the head wing part of the fairing and the left connecting rod 210 of the head wing part of the fairing. The middle front part 102 of the fairing is connected to the cross-domain robot through the middle front connecting rod 211 of the fairing. The pectoral fin imitation part 103 of the fairing is connected to the cross-domain robot through the connecting rod 212 of the pectoral fin imitation part of the fairing. The tail imitation part 104 of the fairing is connected to the robot through the right connecting rod 213 of the tail imitation part of the fairing and the left connecting rod 214 of the tail imitation part of the fairing. Further, there is a concave design between the middle front part 102 of the fairing and the abdominal part 103 of the pectoral fin imitation part of the fairing for accommodating the closed compartment. The fairing covers part of the right track 301 and part of the left track 302. The right front thruster 201 is connected to the cross-domain robot through the right front thruster connecting rod 202 and is hidden on the right side of the head wing part 101 of the fairing. The left front thruster 203 is connected to the cross-domain robot through the left front thruster connecting rod 204 and is hidden on the left side of the head wing part 101 of the fairing. The right rear thruster 205 is connected to the cross-domain robot through the right rear thruster connecting rod 206 and is hidden on the right part of the pectoral fin imitation structure 103 of the fairing. The left rear thruster 207 is connected to the cross-domain robot through the left rear thruster connecting rod 208 and is hidden on the left part of the pectoral fin imitation structure 103 of the fairing. The rear right thruster 215 is connected to the cross-domain robot through the right rear thruster connecting rod 216 and is hidden on the right side of the tail imitation part 104 of the fairing. The rear left thruster 217 is connected to the amphibious robot through the left rear thruster connecting rod 218 and is hidden on the left side of the tail imitation part 104 of the fairing.

[0079] The hammerhead shark-inspired fairing proposed by the present invention can streamline the shape of the tracked-propeller hybrid cross-domain robot during operation, greatly reducing the resistance when it moves on the water surface. It can effectively reduce the energy consumption of the cross-domain robot, improve its navigation speed, navigation mileage, maximum diving depth, increase the continuous operation time of the cross-domain amphibious operation, and enhance the ability of the cross-domain robot to complete underwater tasks.

[0080] Those skilled in the art can easily understand that the above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, and improvements made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A design method of a bionic drag reduction fairing for a water-land cross-domain robot, characterized in that, First, select a marine organism as the bionic object according to the structural characteristics of the water-land cross-domain robot, conduct morphological analysis on the selected bionic object, and extract the contour of the corresponding part of the bionic object. Next, perform parametric modeling on the extracted outer contour, divide the outer contour into a head wing part, a pectoral fin part, and a tail part. The parametric modeling includes three parts, namely parametric modeling of the bionic head wing part, parametric modeling of the bionic pectoral fin part, and parametric modeling of the bionic tail part, to obtain the parametric models of each part. Then, based on the parametric models of each part, and according to the functions and actual working conditions required by the head wing part, pectoral fin part, and tail part respectively, determine the actual parameters of each part, and conduct the physical model design of the head wing part, pectoral fin part, and tail part respectively. Finally, integrate the physical model designs of each part to obtain the overall bionic fairing model. When performing parametric modeling of the bionic head wing part, decompose the outer contour of the hammerhead shark's head into a sine curve along the horizontal direction and an elliptical curve along the horizontal direction, and perform parametric modeling to obtain the parametric model of the head wing part contour. The sine curve along the horizontal direction is composed of three sine functions with different amplitudes. The equation of the sine curve along the horizontal direction is as follows: Among them, A1, A2, and A3 are three different amplitudes of the sine curve, , , are three periods of the sine curve, is the average period, T is the time, x is the abscissa, y is the ordinate.

2. The bionic drag reduction fairing design method for an amphibious cross-domain robot according to claim 1, characterized in that The equation of the elliptical curve along the horizontal direction is: Among them, the meanings of the respective parameters are as follows: a is the major axis of the ellipse, b is the minor axis of the ellipse, , .

3. The bionic drag reduction fairing design method for an amphibious cross - domain robot according to claim 2, characterized in that, The curve equation of the hammerhead shark's head outer contour is as follows: 。 4. The bionic drag reduction fairing design method for an amphibious cross-domain robot according to claim 3, wherein When performing parametric modeling of the bionic pectoral fin part, the pectoral fin part structure is composed of a parabola curve equation and a circle equation. The outer contour of the pectoral fin part is parametrically modeled using the parabola curve equation, and the central through hole on the pectoral fin part is parametrically modeled using the circle equation. Specifically, first determine the axis of symmetry of the parabola, and then set the vertex of the parabola y3 to be (0, k ), and set the parabola equation based on the vertex form y = dx ^2 + k， Establish an outer contour model, d which is the coefficient of the parabola equation, Next, set the center coordinates of the circle (0, y1 ), whose position is determined by the layout of the rear thrusters of the amphibious cross-domain robot. Determine the radius R1 of the circle according to the overall size of the rear thrusters. Based on the circle equation x ^2 + ( y - y1 )^2 = R 1^2, establish the contour model of the central through-hole, Among them, y1 is the vertical coordinate of the center of the circle, x is the horizontal coordinate, y is the vertical coordinate, and R1 is the radius.

5. The bionic drag reduction fairing design method for an amphibious cross-domain robot according to claim 4, wherein When performing parametric modeling of the bionic tail part, according to the outer shape of the hammerhead shark's tail, simplify the tail contour into a rectangular outer contour and a concave tail end in the shape of a quadratic curve. The tail model is composed of a rectangular equation and a quadratic curve equation. First, determine the axis of symmetry of the conic equation, and then set the vertex of the conic equation to be (0, k4 ), and establish a central contour model based on the conic equation Ax^2 + Bxy + Cy^2 + Dx + Ey + F = 0 . Next, set the length m of the rectangle, and then set the width n of the rectangle, and establish a tail parameterization model based on the rectangle equation, where A, B, C, D, E, and F are the coefficients of the conic equation, x is the abscissa, and y is the ordinate.

6. A bionic drag reduction fairing designed by the method according to any one of claims 1-5.

7. The drag-reducing fairing according to claim 6, characterized in that, On both top surfaces of the bionic head wing part of the fairing, round holes (1011) are distributed, and the round holes (1011) cover the thrusters at both front ends of the water-land cross-domain robot. The side surfaces on both sides of the bionic head wing are designed in the shape of a hammer (1013), and its cross-section gradually decreases from the middle to the front and rear ends. A convex arc surface (1014) is designed on the lower side of the front end of the bionic head wing part, and the inner side of the convex arc surface covers the left and right tracks of the water-land cross-domain robot.

8. The drag reduction fairing according to claim 7, characterized in that, The bionic pectoral fin part of the fairing has pectoral fin round holes (1031), and the pectoral fin round holes are distributed on both sides and cover the thrusters at both rear ends of the water-land cross-domain robot. The pectoral fin round holes are through holes, and the connection part (1032) between the side of the pectoral fin and the upper shell is a smooth transition surface. The contour of both side walls of the bionic tail part of the fairing is designed in an arc shape (1041), the top surface (1042) at the upper middle part of the bionic tail of the fairing is in the shape of a downward concave arc, and the bionic tail of the fairing extends backward, having a backward extension part (1043) in the shape of a fish tail.

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