Flapping wing apparatus with conformal antenna and method for searching for field targets thereof

Abstract

The application provides a directional diagram reconfigurable conformal antenna suitable for a two-section flapping-wing aircraft and a field target searching method based on the flapping-wing structure conformal antenna, which comprises a flapping-wing fixed frame, a skin and a printed antenna, the flapping-wing fixed frame comprises an inner frame, an outer frame and a driving rocker, and the printed antenna is arranged on the inner and outer surfaces of the skin. The antenna oscillator, the parasitic patch, the reverser and the director located on the two-section flapping wing are composed, and because the conformal antenna is conformal to the flapping-wing skin, the electromagnetic wave radiation is not interfered by the internal structure. Through simulation verification, the return loss of the conformal antenna at 2.44GHz is‑35dB, and the gain is 7.05dBi. Because the beam angle of the conformal antenna is small, and the flapping-wing flapping when the bionic bird flies, the beam can be scanned in a certain area, and according to the attitude control adjustment of the aircraft, the searching work in the complex mountainous terrain in the field can be realized.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of aircraft technology, more particularly, to a flapping wing device with a conformal antenna and a field target searching method thereof. BACKGROUND

[0002] At present, with the continuous development of wireless communication science, certain progress has been made in the research and design of various forms of antennas. However, due to some special mechanical forms, for example, the internal space of a bionic aircraft is generally occupied by various power systems, transmission mechanisms and structural supports. After considering the working space of the transmission mechanism, the remaining space inside the aircraft is very limited. However, the antenna for receiving and transmitting electromagnetic wave signals is also an indispensable important component. Although the microstrip antenna currently has the advantages of low profile, miniaturization and integration, it will be affected by electromagnetic interference from various metal components inside the body, which will have unpredictable effects on the performance of the antenna. Therefore, the conformal antenna is a new solution to replace the microstrip antenna in the bionic aircraft. Then, based on the bionic aircraft scheme of the conformal antenna, in some special cases such as search and rescue, detection and defect detection, the bionic aircraft can achieve more prominent searching ability by combining the special arrangement of the conformal antenna with special motion postures, such as wider search range and higher precision. Through certain aircraft trajectory posture planning, more complex usage requirements can be achieved.

[0003] CN1925223 discloses a directional pattern reconfigurable antenna with double folding groove structure and its array, which belongs to the field of electronic technology and particularly relates to conformal antenna array technology. The antenna comprises a dielectric substrate (36), a back conductor plate (37) and a coplanar ground plate (35), the coplanar ground plate has double folding grooves, and two antenna radiation arms are connected through a coplanar waveguide transmission line (17); the coplanar waveguide transmission line (17), a bottom electric wire radiation arm (20), a coplanar waveguide feed line (23) and the coplanar ground plate (35) are embedded with corresponding switches or probes, and three state antenna directional pattern scanning can be realized at the same frequency point by changing the working state of the probes or switches. The antenna array takes the antenna as an antenna array unit, distributes it on a carrier curved surface, and keeps the unit pointing in a similar or same radiation directionality. The present application can be applied to the design and production of active phased arrays, passive phased arrays and other various complex curved surface antenna arrays. SUMMARY

[0004] In order to overcome the defects of the prior art, the technical problem to be solved by the present application is to provide a flapping wing device with a conformal antenna and provide a field target searching method based on the conformal antenna. By conforming the antenna to the flapping wing skin, the internal space of the aircraft is saved, more redundancy is left for the transmission structure and the internal structure design of the aircraft body, the far distance communication efficiency is improved by adopting the design of the Yagi-like antenna. Under the above conditions, the flight trajectory of the aircraft carrying the conformal antenna is planned, so as to realize a field target searching method.

[0005] The first object of the present application is to provide a conformal antenna suitable for a two-section flapping wing aircraft with a reconfigurable structural pattern.

[0006] Specifically, the present application provides a flapping wing device with a conformal antenna, which comprises a flapping wing skin, a flapping wing fixed frame, a conformal antenna dipole and a conformal parasitic patch, an antenna reflector and a director.

[0007] The flapping wing skin is arranged on the upper surface of the frame and comprises an inner flapping wing skin and an outer flapping wing skin.

[0008] The flapping wing fixed frame comprises an inner frame, an outer frame and a driving rocker, the outer frame and the inner frame are hinged together through a pivot, the first end of the driving rocker is rotatably connected to the R pair of the outer frame, the second end of the driving rocker is connected to a crank, a sliding groove is arranged on the driving rocker, the inner frame is provided with a sliding rod which is slidingly connected in the sliding groove.

[0009] The inner frame further comprises a fixing structure of the inner flapping wing skin for fixing the inner flapping wing skin, and the outer frame further comprises a fixing structure of the outer flapping wing skin for fixing the outer flapping wing skin.

[0010] The conformal antenna dipole and the conformal parasitic patch are printed on the lower surface of the inner flapping wing skin, and the two ends of the conformal antenna dipole are provided with the conformal parasitic patch.

[0011] The conformal antenna reflector and the conformal antenna director, the conformal antenna reflector is printed on the lower surface of the inner flapping wing skin, and the conformal antenna director is printed on the upper surface of the outer flapping wing skin.

[0012] The conformal antenna director comprises n groups of parallel arranged conformal metal strips, n is an integer greater than 3, the distance between two adjacent conformal metal strip groups is L1=k1λ, L2=k2λ, L3=k3λ, wherein k1, k2, k3∈(0.4, 0.5), λ is the working wavelength of the conformal antenna dipole, and its specific value is determined according to the simulation results in actual design, each conformal metal strip group comprises two collinear conformal metal strips, and the distance between the conformal metal strips in the plurality of conformal metal strip groups is expressed as , θ is the included angle of the "V" shape formed by the combination of the n groups of conformal metal strips. L1, L2, L3, i is 1, 2, 3. In the preferred technical solution of the present application, the length of the conformal antenna reflector is longer than that of the conformal antenna oscillator.

[0013] In the preferred technical solution of the present application, the conformal antenna oscillator adopts a bow-shaped folded oscillator structure, and the length thereof is between 40-60mm.

[0014] In the preferred technical solution of the present application, the outer frame and the inner frame are both made of elastic soft foam material.

[0015] In the preferred technical solution of the present application, the skin is made of carbon fiber and liquid crystal synthetic material.

[0016] Another object of the present application is to provide a field target searching method using the conformal antenna aircraft.

[0017] In the preferred technical solution of the present application, the method is based on the combined action of the reciprocating motion of the two-section flapping wing structure and the high-gain small beam angle of the conformal antenna, can realize the mechanical beam scanning action, and reasonably plans the trajectory according to the bionic attitude of the aircraft, and completes the target searching in the complex terrain in the field.

[0018] In the preferred technical solution of the present application, the beam scanning action is based on the mechanical reciprocating motion of the crank rocker mechanism connected to the outer flapping wing and the inner flapping wing driven by the sliding chute, so that the conformal antenna radiation lobe located on the flapping wing structure also reciprocates within a certain angle, forming the beam scanning action.

[0019] In the preferred technical solution of the present application, the trajectory planning mainly bionically simulates the flight attitude of birds, then reasonably plans, determines the target prediction position by level flight in the complex terrain, and finally completes the field target searching by precise point searching through circling at the prediction position.

[0020] The present application has the following beneficial effects:

[0021] The flapping wing device with the conformal antenna provided by the application is composed of a conformal antenna oscillator, a parasitic patch, a reverser and a director located on the two-section flapping wing, because the antenna is conformal with the flapping wing skin, the electromagnetic wave radiation is not interfered by the internal structure, and better working performance can be achieved, after impedance matching of the antenna oscillator and the remaining structure, simulation verification is carried out, the return loss of the conformal antenna at the 2.44GHz frequency band is-35dB, and the gain is 7.05dBi, the conformal antenna with the above characteristics can realize beam scanning within a certain angle, that is, a wider signal scanning and searching area is obtained. Therefore, when the bionic flying vehicle flies, according to the characteristics of the special structure, certain trajectory planning can be carried out to make it more effectively avoid obstacles in complex mountainous environments, and the conformal antenna beam scanning method is designed, compared with ordinary flying vehicles, the searching of field targets can be more easily completed, and the bionic flying vehicle has advantages in personnel search and rescue, article positioning and wild animal protection. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 Figure 1 is a schematic diagram of one side flapping wing of the two-section flapping wing vehicle based on the reconfigurable conformal antenna provided by the application;

[0023] Figure 2 Figure 2 is a side view of the device shown in Figure 1; Figure 1

[0024] Figure 3 Figure 3 is a top view of the device shown in Figure 1; Figure 1

[0025] Figure 4 Figure 4 is a conformal antenna structure diagram of the device shown in Figure 1; Figure 1

[0026] Figure 5 Figure 5 is an S11 return loss pattern of the conformal antenna shown in Figure 4; Figure 3

[0027] Figure 6 Figure 6 is an S11 return loss pattern of a comparative example antenna;

[0028] Figure 7 Figure 7 is a gain pattern of the conformal antenna shown in Figure 4; Figure 3

[0029] Figure 8 Figure 8 is a conformal antenna direction pattern change range in the two-section flapping wing structure motion shown in Figure 1. Figure 1 DETAILED DESCRIPTION

[0030] The technical solutions of the application will be further described below in combination with the drawings and through specific embodiments.

[0031] As​​​​​​Figure 1 As shown in the embodiments, a flapping wing device with a conformal antenna is provided, which comprises a flapping wing skin, a flapping wing fixed frame, a conformal antenna dipole and parasitic patch, an antenna reflector and director;

[0032] The flapping wing skin is arranged on the upper surface of the frame and comprises an inner flapping wing skin and an outer flapping wing skin.

[0033] The flapping wing fixed frame comprises an inner frame, an outer frame and a driving rocker, the outer frame and the inner frame are hingedly connected together through a pivot, the first end of the driving rocker is rotationally connected to R of the outer frame, the second end of the driving rocker is connected to a crank, the driving rocker is provided with a sliding groove, the inner frame is provided with a sliding rod, and the sliding rod is slidingly connected in the sliding groove.

[0034] The swing angle of the outer flapping wing is 80°-100°, and a part is located on the inner flapping wing with small swing angle, the swing angle of the inner flapping wing is 40°-60°, so that the directional diagram of the conformal antenna can be reconstructed, and a wide space of 150° up and down can be covered, and excellent signal coverage can be ensured under the premise of long-distance communication.

[0035] The conformal antenna located in the inner flapping wing part is composed of three parts, one part is an antenna dipole and a feeding network printed under the flapping wing skin, and two parasitic patches are printed at both ends of the dipole, which are used to increase the bandwidth of the conformal antenna, and a reflector is used to reflect the electromagnetic wave of the main dipole to the direction indicated by the flapping wing.

[0036] In the preferred technical scheme of the present application, the skin comprises an inner flapping wing skin and an outer flapping wing skin, the inner flapping wing skin is pasted on the upper surface of the inner frame, and the outer flapping wing skin is pasted on the upper surface of the outer frame.

[0037] In the preferred technical scheme of the present application, the printed antenna comprises a conformal antenna dipole and parasitic patch, the conformal antenna dipole and parasitic patch are printed on the lower surface of the inner flapping wing skin, and the parasitic patch is arranged at both ends of the conformal antenna dipole.

[0038] In the preferred technical scheme of the present application, the printed antenna further comprises a conformal antenna reflector and a conformal antenna director, the conformal antenna reflector is printed on the lower surface of the inner flapping wing skin, and the conformal antenna director is printed on the upper surface of the outer flapping wing skin.

[0039] In the preferred technical scheme of the present application, the conformal antenna director comprises four conformal metal strip groups, the four conformal metal strip groups are arranged in parallel, each equal-length conformal metal strip group is composed of two conformal metal strips arranged in line, and the distance between the two conformal metal strips in the four equal-length conformal metal strip groups increases in equal proportion with the distance from the conformal antenna dipole.

[0040] In the preferable technical solution of the present application, the length of the conformal antenna reflector is longer than the conformal antenna dipole.

[0041] In the preferable technical solution of the present application, the conformal antenna dipole adopts a butterfly-shaped folded dipole structure with a length of 40-60 mm.

[0042] In the preferable technical solution of the present application, the outer frame and the inner frame are both made of elastic soft foam material.

[0043] As shown in Figure 1 The present application provides a direction pattern reconfigurable conformal antenna based on flapping wing structure, which comprises an inner flapping wing fixed frame 11, an outer flapping wing fixed frame 21, an inner flapping wing skin 12, an outer flapping wing skin 22, a conformal antenna dipole 31, a conformal antenna parasitic patch 32, a conformal antenna reflector 33, and a conformal antenna director 34. The flapping wing fixed frame is made of non-metallic material, generally using elastic soft foam body, which can maintain the stability of the flapping wing structure as much as possible without affecting the performance of the antenna. The flapping wing skin made of carbon fiber and liquid crystal synthetic material is pasted on the upper surface, and the conformal antenna structure, feed network and welding point are printed on the lower surface of the skin. The coaxial line is connected to the signal processing system in the body.

[0044] The inner flapping wing fixed frame 11 and the outer flapping wing fixed frame 21 are connected through a hinge 4 in the middle. The reciprocating swing of the inner flapping wing 1 and the outer flapping wing 2 is driven by the swing of the driving rocker 5 on the inner flapping wing fixed frame 11 driven by the crank 6, which simulates the flapping action of birds in flight to realize the flight behavior of the aircraft. This figure is a left flapping wing schematic diagram, and the right flapping wing is designed to be axially symmetrical with the left flapping wing.

[0045] As shown in Figure 2 The conformal antenna dipole 31 is printed on the lower surface of the inner flapping wing skin 12, which receives and / or emits electromagnetic wave signals of 2.44 GHz frequency band. The conformal antenna reflector 33 is printed on the lower surface of the inner flapping wing skin 12, which is slightly longer than the conformal antenna dipole 31, and is used to reflect the electromagnetic waves emitted by the conformal antenna dipole 31 to the direction of the outer flapping wing 2.

[0046] The conformal antenna dipole 31 adopts a butterfly-shaped folded dipole structure with a length of 40-60 mm. The folded dipole is used to increase the bandwidth of the antenna, and the butterfly shape is used to further improve the narrowband problem of the dipole antenna. The two parasitic patches 32 are printed on the lower surface of the inner flapping wing skin 12, which produce resonant frequency when the conformal antenna dipole works, and are also used to increase the bandwidth of the conformal antenna.

[0047] As shown in Figure 3The shown conformal antenna director 34 is printed on the upper surface of the outer flapping wing skin 22, and the conformal antenna director 34 is composed of multiple groups of collinear equal-length metal strips, and the conformal antenna director includes n groups of parallelly arranged conformal metal strips, n is an integer greater than 3, the distance between two adjacent groups of conformal metal strips is L1=k1λ, L2=k2λ, L3=k3λ, wherein k1, k2, k3∈(0.4, 0.5), λ is the operating wavelength of the conformal antenna oscillator, and the specific value is determined according to the simulation result in actual design, each group of conformal metal strips includes two collinear conformal metal strips, and the distance between the conformal metal strips in the multiple groups of conformal metal strips is expressed as , θ is the included angle of the "V" shape formed by the n groups of conformal metal strips, L1, L2, L3, and i is 1, 2, or 3. The overall distribution is in the shape of "V", and the function is to guide the electromagnetic waves emitted by the conformal antenna oscillator 31 in different directions in the conformal antenna director part, so that interference can be generated between the electromagnetic waves in space, and the gain of the conformal antenna is increased.

[0048] As shown in Figure 4 , the conformal antenna 3 is composed of the conformal antenna oscillator 31, the conformal antenna parasitic patch 32, the conformal antenna reflector 33, and the conformal antenna director 34, and the parts are printed on the inner flapping wing skin 12 and the outer flapping wing skin 22, the inner flapping wing skin 12 is installed on the inner flapping wing fixed frame 11, and the outer flapping wing skin 22 is installed on the outer flapping wing fixed frame 21, so that the antenna function is realized in the shape of conformal with the flapping wing.

[0049] According to the radiation principle of the antenna, when alternating current flows through the conformal antenna oscillator 31, electromagnetic waves uniformly radiated around the straight line where the oscillator is located are generated, at this time, due to the alternating current in the conformal antenna oscillator 31, the parasitic patch 32 also generates a resonant current with a different frequency, so that the bandwidth is increased, as shown in Figure 5 The return loss diagram of the embodiment shows that, compared with Figure 6 the return loss of the comparative example, the bandwidth is increased from 240MHz to 400MHz. The conformal antenna reflector 33 reflects the electromagnetic waves radiated towards the body to another direction, and the conformal antenna director 34 guides the electromagnetic waves to different directions with an angle difference of 10°, the electromagnetic waves in the two directions interfere with each other at the middle position of the angle, the phase is superimposed, so that the transmission distance is farther, and the gain of the conformal antenna is effectively increased, as shown in Figure 7 .

[0050] In the preferred technical solution of the present application, the skin is made of carbon fiber and liquid crystal synthetic material.

[0051] As shown in Figure 8As shown, A and B are two positions of the flapping wing with conformal antenna, and the shaded part is the radiation pattern of the two positions of the flapping wing.

[0052] In order to solve the problem of accurate positioning of the target in the existing complex terrain, the application designs a target searching method for complex terrain in the field, which comprises the following steps:

[0053] S1, taking the vertical axis of the starting position of the aircraft as the Z axis, and the sea level as the XOY plane to establish a space rectangular coordinate system, and bringing the rectangular coordinate system into the preset area map.

[0054] S2, according to the satellite positioning system, the position coordinates (x, y, z) of the aircraft in the established rectangular coordinate system are determined, and the position is updated in real time during flight.

[0055] S3, the maximum search distance of the aircraft is determined as d.

[0056] S4, when the terrain is flat, in order to balance the relationship between the search range and the search accuracy, the flight height of the aircraft from the ground should be less than d / 2, and the flight trajectory is taken as a bird as a simulation object, and a straight line flight is adopted for searching in the plane. Considering the rationality of the search coverage area, the trajectories of the two straight flights of the aircraft should be approximately parallel, and the distance D1 between the straight lines should satisfy When the terrain is complex, the height of the mountain peak is h, if n∈N, (n+2) divides the height of the mountain peak h, the aircraft flies around the mountain peak at a certain distance D2 from the mountain peak at each divided height, and D2 satisfies the condition D2<d / 2.

[0057] S5, obtain the wireless signal emitted by the search target, the conformal antenna is conformal with the flapping wing skin, the flapping wing skin is fixed on the inner and outer frames, when the aircraft flies according to the predetermined flight trajectory, the flapping wing flaps to swing back and forth at a certain angle, which drives the radiation pattern of the conformal antenna to swing back and forth, realizes the mechanical beam scanning, and plans the flight trajectory by fusing the beam scanning to search the signal emitted by the search target;

[0058] S6, analyze the collected signals to determine several expected target positions.

[0059] S7, for each expected target position, fly around a certain range area to detect the signal source and obtain accurate target position information, compare the signal strength RSSI and signal stability of each expected position, and determine the accurate point of the search target; if the accurate point is wrong, return to step S5 to obtain the wireless signal again, and continue to execute the following steps until the accurate point of the search target is obtained.

[0060] The application is described by preferred embodiments, and those skilled in the art know that various changes or equivalent replacements can be made to the features and embodiments without departing from the spirit and scope of the application. The application is not limited by the specific embodiments disclosed herein, and other embodiments falling within the claims of the application are within the scope of the application.

Claims

1. A flapping-wing device with a conformal antenna, characterized in that: It includes flapping wing skin, flapping wing fixing frame, conformal antenna element and conformal parasitic patch, antenna reflector and director; The flapping wing skin is mounted on the flapping wing fixed frame and includes the inner flapping wing skin and the outer flapping wing skin; The flapping wing fixed frame includes an inner frame, an outer frame, and a drive rocker. The outer frame and the inner frame are hinged together by a pivot. The first end of the drive rocker is rotatably connected to the R-joint of the outer frame, and the second end of the drive rocker is connected to a crank. The drive rocker is provided with a groove, and the inner frame is provided with a slide rod, which is slidably connected in the groove. The inner frame also includes the fixing structure for the inner flapping wing skin, and the outer frame also includes the fixing structure for the outer flapping wing skin; Both the conformal antenna element and the conformal parasitic patch are printed on the lower surface of the inner flap skin, and the conformal parasitic patch is disposed at both ends of the conformal antenna element; The conformal antenna reflector is printed on the lower surface of the inner flap skin, and the conformal antenna director is printed on the upper surface of the outer flap skin. The conformal antenna director comprises n parallel conformal metal strip groups, where n is an integer greater than 3. The distances between two adjacent conformal metal strip groups are L1=k1λ, L2=k2λ, and L3=k3λ, where k1, k2, and k3 ∈ (0.4, 0.5), and λ is the operating wavelength of the conformal antenna element, the specific value of which is determined according to the simulation results during actual design. Each conformal metal strip group includes two collinear conformal metal strips, and the distance expression between the conformal metal strips in the n conformal metal strip groups is: θ is the "V"-shaped angle formed by the combination of n conformal metal strip groups, and L n Let L1, L2, L3 be numbers, and i be numbers 1, 2, 3.

2. The flapping-wing device with a conformal antenna according to claim 1, characterized in that: The conformal antenna reflector is longer than the conformal antenna element.

3. The flapping-wing device with a conformal antenna according to claim 2, characterized in that: The conformal antenna element adopts a butterfly-shaped folded element structure, with a length between 40-60mm.

4. The flapping-wing device with a conformal antenna according to claim 3, characterized in that: The conformal metal strip group includes four conformal metal strip groups of equal length, and the spacing between the two equal-length metal strips in the four conformal metal strip groups increases proportionally with the distance from the conformal antenna vibrator.

5. The flapping-wing device with a conformal antenna according to claim 3, characterized in that: Both the outer frame and the inner frame are made of elastic soft foam material.

6. The flapping-wing device with a conformal antenna according to claim 2, characterized in that: The flapping wing skin is made of carbon fiber and liquid crystal composite material.

7. A method for searching a target in the field using a flapping-wing device with a conformal antenna according to any one of claims 1 to 6, characterized in that, Includes the following steps: S1. Establish a spatial rectangular coordinate system with the vertical axis where the aircraft's starting position is located as the Z-axis and the sea level as the XOY plane. Then, input this rectangular coordinate system into the preset regional map. S2. Based on the satellite positioning system, determine the position coordinates (x, y, z) of the aircraft in the established rectangular coordinate system, and update this position in real time during flight; S3. Determine the maximum search distance of the aircraft as d; S4. In flat terrain, to balance the search range and search accuracy, the aircraft's altitude above the ground should be less than d / 2. The search should be conducted by straight-line flight within a plane. Considering the integrity of the search coverage area, the trajectories of the aircraft's two straight-line flights should be parallel, and the distance D1 between the lines should meet the following requirements. In complex mountainous terrain, assuming the peak height is h, if... Let n∈N, and divide the mountain peak height h into (n+2) equal parts. The aircraft will fly around the mountain peak at each of these equal height divisions, maintaining a distance D2 from the peak. D2 satisfies the condition D2. <d / 2; S5. Obtain the wireless signal emitted by the target. The conformal antenna conforms to the flapping wing skin, which is fixed on the inner and outer frames. When the aircraft flies along the predetermined flight path, the flapping wing flaps back and forth at a certain angle, causing the conformal antenna's radiation pattern to swing back and forth, thus achieving mechanical beam scanning. The flight path of the fused beam scanning is used to plan and search for the signal emitted by the target. S6. Analyze the collected signals to determine the locations of several expected targets with a high probability. S7. Perform fly-around detection on a certain range of each expected target location to determine the signal source, obtain accurate target location information, compare the signal strength RSSI and signal stability of each expected location, and determine the accurate location of the searched target. If the exact location is incorrect, return to step S5, regain the wireless signal, and continue with the following steps until the exact location of the search target is obtained.

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