Underwater active spin-on optical beacon guidance system and method

Abstract

The application relates to an underwater active rotating optical beacon guiding system and method, wherein a light cylinder and a mirror rotating mechanism are arranged in a mounting shell, the mirror rotating mechanism comprises a driving gear, the driving gear is rotatably arranged on the upper end of the light cylinder, a light source lampwick is arranged in the lower end of the light cylinder, an adjustable height lens is arranged in the light cylinder, a transparent protective cover is arranged on the upper side of the mounting shell, and the mirror is obliquely arranged in the transparent protective cover, the mirror is rotated by the driving gear, the light emitted by the light source lampwick first passes through the lens, is reflected by the mirror and is output by the transparent protective cover. The application prolongs the effective action distance of the output light by changing the emission angle of the beacon, and realizes 360-degree rotating dynamic scanning of the output light by the mirror rotating mechanism, so that the effective action angle of the output light is expanded to the full angle, thereby solving the problems of the limited emission angle and short action distance of the traditional light guiding beacon.

Description

Technical Field

[0001] This invention relates to the field of underwater robots, specifically to an underwater active rotating optical beacon guidance system and method. Background Technology

[0002] Autonomous underwater vehicles (AUVs) have always been a research hotspot in the field of unmanned underwater vehicles (UUVs). They have been widely used in marine scientific research, marine resource surveys, and marine safety assurance. Among these applications, navigation and positioning are key to AUVs planning their underwater mission paths.

[0003] AUV optical navigation refers to the method of guiding an AUV's navigation using optical sensors. At close range, optical positioning enables AUVs to achieve extremely high accuracy and stability during operation; therefore, optical positioning has become the primary means of precise close-range underwater positioning. Currently, AUV optical navigation has become a crucial component of AUV navigation technology, playing a vital role in achieving autonomous navigation for AUVs.

[0004] Key performance indicators for underwater optical positioning include operating range, accuracy, and update frequency. In recent years, with advancements in computer vision and hardware upgrades, optical methods have improved accuracy to the centimeter level and achieved real-time update frequencies. However, for AUVs, the transmission of optical signals in water is significantly affected by water quality, such as… Figure 4 As shown, the transmission distance of optical signals in water increases as the angle decreases, and traditional optical beacons need to consider both angle and transmission distance. Therefore, their operating range is usually only a fan shape, and both the angle and transmission distance are greatly limited. Summary of the Invention

[0005] The purpose of this invention is to provide an underwater active rotating optical beacon guidance system and method, which extends the effective range of the output light by changing the emission angle of the beacon, and realizes 360° rotational dynamic scanning of the output light plane through a mirror rotation mechanism, thereby expanding the effective range of the output light to the full angle, thus solving the problems of limited emission angle and short range of traditional optical guidance beacons.

[0006] The objective of this invention is achieved through the following technical solution:

[0007] An underwater active rotating optical beacon guidance system includes a mounting housing, a transparent shield, an optical tube, a reflector, and a reflector rotation mechanism. Both the optical tube and the reflector rotation mechanism are housed within the mounting housing. The reflector rotation mechanism includes a drive gear rotatably mounted on the upper end of the optical tube. A light source wick is located inside the lower end of the optical tube. An adjustable-height lens is located inside the optical tube. The transparent shield is mounted on the upper side of the mounting housing, and the reflector is tilted within the transparent shield. The reflector is rotated by the drive gear. Light emitted from the light source wick first passes through the lens, then is reflected by the reflector and output from the transparent shield.

[0008] The reflector is housed in a reflector bracket. The drive gear has multiple screws, and the reflector bracket has multiple screw holes along its edge. Each screw hole is fitted onto a corresponding screw. The drive gear has multiple screw sleeves, and the lower end of each screw is threaded into a corresponding screw sleeve. The upper end of each screw sleeve has a pad with an inclined surface. The pad is threaded onto the corresponding screw, and the inclined surface on the upper side of the pad mates with the reflector bracket.

[0009] The reflector bracket includes a base plate and a side frame, wherein the side frame is located on the edge of the base plate and has multiple screw holes.

[0010] The upper end of the light tube is provided with a bearing bracket, and the bearing bracket contains a bearing that supports the rotation of the drive gear. The lower end of the light tube is provided with a heat sink, and the light source wick is located on the heat sink.

[0011] The mirror rotation mechanism includes a motor, a motor gear, and a drive gear, wherein the motor is fixed in the mounting housing, and the motor gear is mounted on the output shaft of the motor and meshes with the drive gear.

[0012] The light tube is equipped with a motor mounting plate, and the motor is mounted on the motor mounting plate.

[0013] The optical tube is provided with two lens mounting seats, and the lens is clamped and fixed by the two lens mounting seats. The outer wall of the lens mounting seat is provided with an external thread that engages with the thread of the inner hole of the optical tube. The edge of the lens mounting seat near the lens is provided with a slot, and the edge of the lens is provided with a locking block.

[0014] The mounting housing includes an upper housing and a lower end plate, and a housing sealing ring is provided between the upper housing and the lower end plate. The lower end of the transparent cover is fixed to the top plate of the upper housing, and a cover sealing ring is provided between the transparent cover and the top of the upper housing. A watertight connector is provided on one side plate of the upper housing.

[0015] The lower end of the transparent cover is fixed to the top plate of the upper shell by a cover locking ring.

[0016] A guidance method based on the aforementioned underwater active rotating optical beacon guidance system, characterized by comprising the following steps:

[0017] Step 1: Determine the AUV camera's frame rate, the beacon's observable angle, the beacon's permissible error, and the AUV camera's maximum scan rate. The AUV camera's maximum scan rate sˊ is calculated using the following formula:

[0018] sˊ=f / (360° / a);

[0019] In the above formula, f is the frame rate of the AUV camera, and a is the observable angle of the beacon;

[0020] Step 2: Before positioning the AUV, confirm the time synchronization between the AUV and the base station through the time synchronization system. Then, the AUV control module obtains the theoretical angle position of the center line of the light output by the transparent shield at any time by calculating the time / angular rate.

[0021] Step 3: The AUV control module compares the angular position of the center line of the output light from the transparent shield observed by the AUV camera after the reflector has rotated two revolutions, and determines whether the actual observation error of the AUV camera is within the beacon's allowable error range. Specifically:

[0022] 1. When the AUV camera is positioned between the angular positions of the center line of the output light rays from the transparent shield during two observations, the actual error eˊ is calculated using the following formula:

[0023] eˊ=(360×s) / fe;

[0024] In the above formula, s is the scanning rate of the AUV camera, f is the frame rate of the AUV camera, and e is the beacon tolerance error;

[0025] 2. When the AUV camera is within the beacon observation error range of the center line angle of the output light from the transparent shield, the transparent shield observed in this instance shall be regarded as facing the AUV.

[0026] The advantages and positive effects of this invention are as follows:

[0027] 1. This invention reduces the emission angle of the output light to effectively increase the transmission distance of the guide light. However, reducing the emission angle also leads to a small working range of the output light plane. Therefore, this invention uses a mirror rotation mechanism to drive the mirror to rotate, thereby realizing the dynamic scanning of the output light in a 360° rotation on the plane. By trading time for space, a long-distance guiding working range of 360° full angle is obtained.

[0028] 2. In this invention, the light emitted from the light source chip first passes through a lens, and then is reflected by a reflector to form output light that is output through a transparent cover. This invention allows for adjustment of the output light by moving the lens mounting bracket to change the lens position. For example, the lens can be used to focus the beam to increase the effective distance of the output light or to diverge the beam to increase the effective angle. Furthermore, the reflector is mounted in a reflector bracket, the height of which is adjustable. The invention also allows for changing the tilt angle of the reflector by replacing reflector brackets with different tilt angles and matching pads, making it more flexible in use.

[0029] 3. This invention forms a new guidance method in which, as long as the scanning rate of the AUV camera is less than the maximum allowable scanning rate, the reflector can ensure that the output light at a certain angle position is always observed by the AUV camera for each rotation. By comparing the angle position of the center line of the output light from the transparent shield observed by the AUV camera after the reflector has rotated two times, it is determined whether the actual observation error of the AUV camera is within the allowable error range of the beacon, and thus it is determined whether the beacon light source is facing the AUV. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of the structure of the present invention.

[0031] Figure 2 for Figure 1 A schematic diagram showing the assembly of the optical tube, lens, and lens mount.

[0032] Figure 3 This is a schematic diagram of the light output path when the present invention is used.

[0033] Figure 4 This is a schematic diagram of the working range of the present invention.

[0034] Figure 5 This is a schematic diagram illustrating the positioning error calculation method of the present invention.

[0035] Figure 6 This is a schematic diagram of the electrical principle of the present invention.

[0036] Among them, 1 is a transparent protective cover, 2 is a protective cover locking ring, 3 is a protective cover sealing ring, 4 is an upper housing, 5 is a motor gear, 6 is a motor mounting plate, 7 is a motor, 8 is a watertight connector, 9 is a housing sealing ring, 10 is a lower end plate, 11 is a heat sink, 12 is a light source wick, 13 is a light tube, 14 is a lens, 141 is a locking block, 15 is a lens mounting base, 151 is a slot, 152 is an external thread, 16 is a bearing bracket, 17 is a bearing, 18 is a drive gear, 19 is a screw, 191 is a screw sleeve, 20 is a pad, 21 is a reflector, 22 is a side frame, 23 is a bracket base plate, 24 is a reflector bracket, and 25 is a mounting housing. Detailed Implementation

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

[0038] like Figures 1-6 As shown, the present invention includes a mounting housing 25, a transparent protective cover 1, a light tube 13, a reflector 21, and a reflector rotation mechanism. The light tube 13 and the reflector rotation mechanism are both disposed in the mounting housing 25. The reflector rotation mechanism includes a drive gear 18, which is rotatably disposed on the upper end of the light tube 13. A light source wick 12 is disposed in the lower end of the light tube 13. An adjustable-height lens 14 is disposed inside the light tube 13. The transparent protective cover 1 is disposed on the upper side of the mounting housing 25, and the reflector 21 is inclinedly disposed in the transparent protective cover 1. The reflector 21 is driven to rotate by the drive gear 18.

[0039] like Figure 1 As shown, in this embodiment, the reflector 21 is disposed in a reflector bracket 24, the drive gear 18 is provided with a plurality of screws 19, the reflector bracket 24 is provided with a plurality of screw holes along its edge, and each screw hole is respectively fitted onto the corresponding screw 19 to achieve the tilting setting of the reflector bracket 24. The drive gear 18 drives the reflector bracket 24 and the reflector 21 to rotate through each screw 19.

[0040] like Figure 1 As shown, in this embodiment, the reflector bracket 24 includes a bracket base plate 23 and a side frame 22, wherein the side frame 22 is located on the edge of the bracket base plate 23 and has a plurality of screw holes. The upper side of the reflector 21 is in close contact with the bracket base plate 23, and the edge of the reflector 21 is fixed by the side frame 22. The screw holes on the side frame 22 are respectively fitted onto the corresponding screws 19.

[0041] like Figure 1 As shown, in this embodiment, the drive gear 18 is provided with multiple screw sleeves 191 of different heights. The lower end of each screw 19 is threaded into the corresponding screw sleeve 191. The upper end of the screw sleeve 191 is provided with a pad 20 with an inclined upper surface. The pad 20 is threaded onto the corresponding screw 19, and the inclined surface on the upper side of the pad 20 cooperates with the reflector bracket 24. The present invention can adjust the height of the reflector 21 by replacing the pads 20 of different heights. In addition, the present invention can also change the tilt angle of the reflector 21 by replacing the reflector bracket 24 and the matching pads 20 with different tilt angles. In this embodiment, the tilt angle of the reflector 21 is 45°.

[0042] like Figure 1 As shown, in this embodiment, the upper end of the light tube 13 is provided with a bearing bracket 16, and the bearing bracket 16 is provided with a bearing 17 to support the rotation of the drive gear 18.

[0043] like Figure 1 As shown, in this embodiment, the reflector rotation mechanism includes a motor 7, a motor gear 5, and a drive gear 18, wherein the motor 7 is fixed in the mounting housing 25, and the motor gear 5 is mounted on the output shaft of the motor 7 and meshes with the drive gear 18.

[0044] like Figure 1 As shown, in this embodiment, a motor fixing plate 6 is provided between the upper end of the light tube 13 and the bearing bracket 16, and the motor 7 is installed on the motor fixing plate 6.

[0045] like Figure 1 As shown, in this embodiment, the optical tube 13 is provided with two lens holders 15, and the lens 14 is clamped and fixed by the two lens holders 15, wherein... Figure 2 As shown, the outer wall of the lens holder 15 is provided with an external thread 152 that engages with the inner hole of the optical tube 13. By rotating the two lens holders 15, their positions within the optical tube 13 can be changed, thereby altering the position of the clamped lens 14. Figure 2 As shown, in this embodiment, the lens holder 15 has a slot 151 on its edge near the lens 14, and the lens 14 has a locking block 141 on its edge. The locking block 141 is embedded in the corresponding slot 151 on the lens holder 15 to position the lens 14. The side of the lens holder 15 away from the lens 14 may be provided with a threaded hole or other structure to facilitate tightening, which is a well-known technology in the art. This invention can change the position of the lens 14 by moving the lens holder 15, thereby achieving the function of adjusting the output light. For example, the lens 14 can be used to focus the beam to increase the effective distance of the output light or to diverge the beam to increase the effective angle.

[0046] In this embodiment, the lens 14 is a Fresnel lens.

[0047] like Figure 1 As shown, in this embodiment, the lower end of the light tube 13 is provided with a heat sink 11, and the light source wick 12 is disposed on the heat sink 11.

[0048] like Figure 1 As shown, in this embodiment, the mounting housing 25 includes an upper housing 4 and a lower end plate 10 disposed on the lower side of the upper housing 4. A housing sealing ring 9 is provided between the upper housing 4 and the lower end plate 10. The lower end of the transparent cover 1 is fixed to the top plate of the upper housing 4 by a cover locking ring 2. The cover locking ring 2 is fixed to the top plate of the upper housing 4 by bolts and presses against the outer flange at the lower end of the transparent cover 1. A cover sealing ring 3 is provided between the transparent cover 1 and the upper housing 4. A watertight connector 8 is provided on one side plate of the upper housing 4 to realize the circuit connection. The watertight connector 8 is a technology known in the art.

[0049] The working principle of this invention is as follows:

[0050] like Figure 1 As shown, during installation, the heat sink 11 with the light source wick 12 is first fixed to the lower end plate 10 of the mounting housing 25 with bolts. Then, the lens mounting base 15 and the lens 14 are placed into the light tube 13, and the position of the lens 14 is adjusted by adjusting the position of the lens mounting base 15. After adjustment, the lower end of the light tube 13 is installed on the heat sink 11. Then, the motor mounting plate 6 is installed on the upper end of the light tube 13, and the bearing bracket 16, bearing 17, and drive gear 18 are installed on the motor mounting plate 6. Then, the motor 7 and motor gear 5 are installed on the motor mounting plate 6, and the motor gear 5 is properly meshed with the drive gear 18. Then, remove the drive gear 18 and install the screw 19, pad 20, and reflector bracket 24 on the drive gear 18. Then, reinstall the drive gear 18 in the bearing bracket 16. Then, install the watertight connector 8 on one side of the upper housing 4 of the mounting housing 25 and connect the electrical circuit. Then, fasten the upper housing 4 onto the lower end plate 10 with the housing sealing ring 9 and fix it. Finally, fasten the transparent cover 1 onto the reflector bracket 24, and fix the lower end of the transparent cover 1 to the top plate of the upper housing 4 by the cover locking ring 2. Before fixing, the cover sealing ring 3 needs to be set on the top plate of the upper housing 4 to complete the installation.

[0051] After the invention is assembled, the heat sink 11 on the lower side of the light source wick 12 is in close contact with the lower end plate 10 of the mounting housing 25, thereby efficiently completing the heat conduction of the electronic device. When applied to an underwater environment, the protective cover sealing ring 3 and the housing sealing ring 9 effectively ensure internal sealing.

[0052] like Figure 3 As shown, during operation, the light emitted by the light source wick 12 first passes through the lens 14, then is reflected by the reflector 21, and finally exits through the transparent cover 1. Figure 4 As shown, the reflector 21 is driven to rotate by the reflector rotation mechanism, thereby realizing a 360° rotation of the output light plane.

[0053] During guidance, AUVs typically navigate at a constant depth, thus simplifying the docking process into movement on a top-down plane. For example... Figure 4 As shown, traditional beacons typically emit at angles ranging from 30° to 120°, depending on the system design. However, due to the absorption and scattering effects of water, and limited by the luminous power, the distance light travels in water is severely restricted (generally within 10 meters), thus limiting the operational range. Figure 4The present invention reduces the emission angle and uses a focused light source to effectively increase the transmission distance of the guide light (to 20-30 meters at the same power). However, the small emission angle also brings the problem of a small working range on the plane. Therefore, the present invention uses a 360° rotating dynamic scanning method on the plane to exchange time for space and obtain a long-distance guidance working range of 360° all angles.

[0054] The guiding method of the present invention is specifically as follows:

[0055] Step 1: Determine the AUV camera's frame rate, the beacon's observable angle, the beacon's permissible error, and the AUV camera's maximum scan rate. The AUV camera's maximum scan rate sˊ is calculated using the following formula:

[0056] sˊ=f / (360° / a);

[0057] In the above formula, f is the frame rate of the AUV camera and a is the observable angle of the beacon.

[0058] For example, in one application of this invention, it is assumed that the AUV camera has a frame rate f = 60 Hz, the beacon light's observable angle a = 10°, and the beacon observation error e = 2°, where the beacon observation error is as follows: Figure 4 As shown, normally when the center line of the output light from the beacon light source (i.e., the transparent shield 1 of this invention) is on the same straight line as the AUV camera (i.e., when the error is e = 0°), the beacon light source is considered to be directly facing the AUV. However, the beacon observation error e = 2° means that the AUV camera is within a 2° error range to the left and right of the center line of the output light from the beacon light source, which can also be considered as the AUV camera being able to identify the beacon light source as directly facing the AUV. Furthermore, the AUV camera's scanning rate is s (rps). Considering the limited observation angle of the AUV, the maximum scanning rate in this application example that ensures the AUV camera does not miss any observations is sˊ = 60 frames / (360° / 10°) = 1.67 rps, that is, as... Figure 4 As shown, when the scanning rate is less than the maximum rate of 1.67 rps, the reflector 21 of the present invention can ensure that the output light at a certain angle position is always observed by the 60 Hz AUV camera for each rotation.

[0059] Step 2: Before positioning the AUV, confirm the time synchronization between the AUV and the base station through the time synchronization system. Then, the AUV control module can obtain the theoretical angle position of the center line of the output light of the transparent shield 1 of the present invention at any time by calculating the time / angular rate.

[0060] Step 3: As Figure 5 As shown, the AUV control module compares the angle position of the center line of the output light from the transparent shield 1 observed by the AUV camera after the reflector 21 of the present invention rotates two revolutions, and determines whether the actual observation error of the AUV camera is within the allowable error range of the beacon.

[0061] As mentioned above, after the AUV camera observes the beacon light (i.e., transparent shield 1), if there is no observation error (e = 0°), it can be assumed that the current AUV position is on the theoretical angular position ray of the center line of the beacon light source output light. However, if... Figure 5 As shown, due to observation errors and factors such as light scattering, there is always an observation error in the AUV camera. Therefore, it is necessary to discuss the error caused by observation between the theoretical and actual angular positions of the center line of the beacon light source output rays, which can be divided into two cases:

[0062] I. For example Figure 5 As shown, when the AUV camera is positioned between the angular positions of the center line of the output light from the beacon light source (i.e., transparent shield 1) during the two observations (i.e.,... Figure 5 When the range is A in the formula, the actual error eˊ is calculated according to the following formula:

[0063] eˊ=(360×s) / fe;

[0064] Where s is the scanning rate of the AUV camera, f is the frame rate of the AUV camera, and e is the beacon tolerance error. The accuracy calculation in the above formula is related to the scanning rate s. For example, in the above application example, when s = 1, the positioning error of the AUV camera is 4°, which does not meet the requirements. When s is 0.5, the positioning error is 2°, which meets the requirements.

[0065] 2. When the AUV camera is within the beacon observation error e = 2° of the center line of the output light of the observed beacon light source, the beacon light source observed in this instance can be regarded as being directly facing the AUV.

[0066] The electrical principle of this invention is as follows: Figure 6 As shown, the positioning control cabin, along with its timer and the present invention, are all located in the target system base station. The positioning control cabin supplies power to the light source wick 12 and the motor 7 and controls the motor 7 to drive the reflector 21 to rotate. The motor 7 has a positioning rotation function. The AUV underwater camera observes the light output of the beacon light source (transparent cover 1) and transmits it to the underwater robot control module for identification and guidance of the underwater robot's movement. Before guidance, the underwater robot and the base station positioning control cabin synchronize the timer through time synchronization. Then, the current angle is distinguished by the agreed rotation strategy and the current timer time.

Claims

1. An underwater active rotating optical beacon guidance system, characterized in that: The system includes a mounting housing (25), a transparent shield (1), a light tube (13), a reflector (21), and a reflector rotation mechanism. The light tube (13) and the reflector rotation mechanism are both located in the mounting housing (25). The reflector rotation mechanism includes a drive gear (18), which is rotatably located at the upper end of the light tube (13). A light source wick (12) is located at the lower end of the light tube (13). An adjustable lens (14) is located inside the light tube (13). The transparent shield (1) is located on the upper side of the mounting housing (25), and the reflector (21) is tilted inside the transparent shield (1). The reflector (21) is rotated by the drive gear (18). The light emitted by the light source wick (12) first passes through the lens (14), and then is reflected by the reflector (21) and output from the transparent shield (1). The reflector (21) is housed in a reflector bracket (24). The drive gear (18) is provided with multiple screws (19). The reflector bracket (24) has multiple screw holes along its edge, and each screw hole is fitted onto the corresponding screw (19). The drive gear (18) is provided with multiple screw sleeves (191). The lower end of each screw (19) is threaded into the corresponding screw sleeve (191). The upper end of the screw sleeve (191) is provided with a pad (20) with an inclined upper surface. The pad (20) is threaded onto the corresponding screw (19), and the inclined surface on the upper side of the pad (20) cooperates with the reflector bracket (24).

2. The underwater active rotating optical beacon guidance system according to claim 1, characterized in that: The reflector bracket (24) includes a bracket base plate (23) and a side frame (22), wherein the side frame (22) is located on the edge of the bracket base plate (23) and has multiple screw holes.

3. The underwater active rotating optical beacon guidance system according to claim 1, characterized in that: The upper end of the light tube (13) is provided with a bearing bracket (16), and the bearing bracket (16) is provided with a bearing (17) to support the rotation of the drive gear (18). The lower end of the light tube (13) is provided with a heat sink (11), and the light source lamp core (12) is provided on the heat sink (11).

4. The underwater active rotating optical beacon guidance system according to claim 1, characterized in that: The mirror rotation mechanism includes a motor (7), a motor gear (5), and a drive gear (18), wherein the motor (7) is fixed in the mounting housing (25), and the motor gear (5) is mounted on the output shaft of the motor (7) and meshes with the drive gear (18).

5. The underwater active rotating optical beacon guidance system according to claim 4, characterized in that: The light tube (13) is provided with a motor fixing plate (6), and the motor (7) is installed on the motor fixing plate (6).

6. The underwater active rotating optical beacon guidance system according to claim 1, characterized in that: The optical tube (13) is provided with two lens holders (15), and the lens (14) is clamped and fixed by the two lens holders (15). The outer wall of the lens holder (15) is provided with an external thread (152) that is threaded to the inner hole of the optical tube (13). The edge of the lens holder (15) near the lens (14) is provided with a slot (151), and the edge of the lens (14) is provided with a locking block (141).

7. The underwater active rotating optical beacon guidance system according to claim 1, characterized in that: The mounting housing (25) includes an upper housing (4) and a lower end plate (10), and a housing sealing ring (9) is provided between the upper housing (4) and the lower end plate (10). The lower end of the transparent cover (1) is fixed to the top plate of the upper housing (4), and a cover sealing ring (3) is provided between the transparent cover (1) and the top of the upper housing (4). A watertight connector (8) is provided on one side plate of the upper housing (4).

8. The underwater active rotating optical beacon guidance system according to claim 7, characterized in that: The lower end of the transparent cover (1) is fixed to the top plate of the upper shell (4) by the cover locking ring (2).

9. A guidance method for an underwater active rotating optical beacon guidance system according to claim 1, characterized in that: Includes the following steps: Step 1: Determine the AUV camera's frame rate, the beacon's observable angle, the beacon's permissible error, and the AUV camera's maximum scan rate. The AUV camera's maximum scan rate sˊ is calculated using the following formula: sˊ=f / (360° / a); In the above formula, f is the frame rate of the AUV camera, and a is the observable angle of the beacon; Step 2: Before positioning the AUV, confirm the time synchronization between the AUV and the base station through the time synchronization system. Then, the AUV control module obtains the theoretical angle position of the center line of the output light of the transparent shield (1) at any time by calculating the time / angular rate. Step 3: The AUV control module compares the angle position of the center line of the output light from the transparent shield (1) observed by the AUV camera after the reflector (21) has rotated two revolutions, and determines whether the actual observation error of the AUV camera is within the allowable error range of the beacon, specifically:

1. When the AUV camera is positioned between the angular positions of the center line of the output light from the transparent shield (1) during two observations, the actual error eˊ is calculated according to the following formula: eˊ=(360×s) / fe ; In the above formula, s is the scanning rate of the AUV camera, f is the frame rate of the AUV camera, and e is the beacon tolerance error; 2. When the AUV camera is within the beacon's allowable error range of the angle position of the center line of the output light of the observed transparent shield (1), the transparent shield (1) observed in this instance shall be regarded as facing the AUV.

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