Position correction system for multiple underwater vehicles using dynamic and static acoustic beacons

Abstract

To provide a position correction system for multiple underwater vehicles using dynamic and static acoustic beacons, thereby enabling underwater observation through control of multiple groups of underwater vehicles.SOLUTION: A position correction system for multiple underwater vehicles 20 using dynamic acoustic beacon 10B and static acoustic beacon 10A, includes: the static acoustic beacon 10A having beacon acoustic means 11 that always has a known absolute position and is capable of being positioned and / or ranged; and an underwater vehicle 20 having vehicle acoustic means 21 capable of positioning and / or ranging, position storage means 22 for storing the absolute position of the static acoustic beacon 10A, and position correction means 23 for correcting absolute and relative positions. The position correction means 23 corrects the vehicle absolute position of the underwater vehicle 20 on the basis of a result of positioning the static acoustic beacon 10A by the vehicle acoustic means 21 and the stored absolute position, and further corrects relative positions among the plurality of underwater vehicles 20 by positioning the relative positions among the plurality of underwater vehicles 20 using the vehicle acoustic means 21.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a position correction system for multiple underwater vehicles, in which multiple underwater vehicles that perform bottom observations or the like correct their estimated positions by themselves. [Background technology]

[0002] A technique is known in which multiple underwater vehicles are deployed into a survey area and used to conduct resource exploration under the control of a surface vessel or the like. For example, Patent Document 1 discloses a target position determination device for a surface vehicle that determines a target position for navigation of the surface vehicle that is tracking multiple underwater vehicles traveling underwater, and the device includes a selection unit that selects a reference underwater vehicle, which is one or more underwater vehicles from the multiple underwater vehicles to be used in calculating the target position, a first acquisition unit that acquires position information indicating the position of the reference underwater vehicle, a target position determination unit that determines the target position based on the position information of the reference underwater vehicle, and an instruction unit that outputs the determined target position to a navigation control device that controls the navigation of the surface vehicle to the target position, and the selection unit excludes from the reference underwater vehicle any underwater vehicles that are determined to have completed communication with the surface vehicle that has moved to the determined target position, and selects the remaining underwater vehicles as reference underwater vehicles for determining the next target position. Patent Document 2 also discloses a positioning device that includes a distance acquisition unit that acquires the distances from a main vehicle to a first underwater vehicle, a second underwater vehicle, and a third underwater vehicle, and a measurement unit that acquires position information for the first and second underwater vehicles, where the distance acquisition unit acquires the distances between the first and third underwater vehicles and the distances between the second and third underwater vehicles based on the propagation time of sound waves between the first and third underwater vehicles and the propagation time of sound waves between the second and third underwater vehicles, and the measurement unit acquires position information for the third underwater vehicle based on the position information of the main vehicle, the first underwater vehicle, and the second underwater vehicle, the distance between the main vehicle and the third underwater vehicle, the distance between the first and third underwater vehicle, and the distance between the second and third underwater vehicles. Patent document 3 also discloses a method for monitoring an underwater vehicle, which includes a behavioral history acquisition step of acquiring a behavioral history including the navigation route obtained by the underwater vehicle via a communication means based on a predetermined period or instruction signal, a positioning information acquisition step of measuring the three-dimensional position of the underwater vehicle using an acoustic positioning device and acquiring positioning information, a behavioral history reproduction step of comparing the behavioral history and positioning information at the same time and correcting the behavioral history based on the positioning information to reproduce the correct behavioral history, and a monitoring information provision step of providing the reproduced correct behavioral history for monitoring the underwater vehicle. In addition, Non-Patent Document 1 proposes a control method for creating a stable acoustic communication and positioning environment by using a formation consisting of a leader aircraft (ASV) and follower aircraft (navigation-type AUVs). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-33464 [Patent Document 2] Japanese Patent Publication No. 2023-123041 [Patent Document 3] Japanese Patent Application Publication No. 2023-67304 [Non-patent literature]

[0004] [Non-Patent Document 1] Takumi Sato and 4 others, "Stabilization of Seafloor Mineral Resource Surveys by Formation Control of Navigation-Type AUVs", National Research and Development Agency, National Institute of Maritime, Port and Aviation Technology, National Maritime Research Institute, July 28, 2020, Poster Session, 20th Research Presentation Meeting Summary of the Invention [Problem to be solved by the invention]

[0005] To achieve group control of multiple underwater vehicles, it is necessary to correct the absolute positions of the underwater vehicles and the relative positions between the underwater vehicles. Underwater vehicles estimate their own position using sensors such as an inertial navigation system (INS) and a ground speed indicator mounted on the vehicle. However, at high altitudes (150 m or more above the seabed) where ground speed cannot be obtained, only water speed can be measured, which means that tidal currents have a significant impact on self-position estimation. In addition, random errors in sensors accumulate over time, resulting in errors in self-position estimation. These self-position estimation errors cause errors in the absolute position information of the observation data, which reduces the reliability of the observation data. Furthermore, it is difficult to maintain the desired relative position between underwater vehicles due to errors in self-position estimation and the influence of tidal currents. If errors occur in the assumed relative position, the risk of collision between underwater vehicles increases and the quality of observation deteriorates due to mutual interference of acoustic waves between the observation equipment installed on each underwater vehicle. Conventionally, acoustic positioning and communication from ships and other vehicles has been used as a method for correcting the position of an underwater vehicle. However, because this method involves acoustic positioning and communication from above the water to the underwater vehicle, as the distance between the ship and the underwater vehicle increases, problems arise, such as an increase in acoustic positioning error, a deterioration in acoustic positioning communication stability, a decrease in the frequency of acoustic positioning communication, and an increase in acoustic positioning communication delay. When positioning an underwater vehicle, delays in the positioning signal due to the long distance result in an increase in positioning error.

[0006] Therefore, the present invention aims to provide a position correction system for multiple underwater vehicles using dynamic and static acoustic lighthouses, which enables underwater observation by controlling a group of multiple underwater vehicles to perform underwater observation while maintaining their relative positional relationships within a certain range. [Means for solving the problem]

[0007] A position correction system for multiple underwater vehicles using dynamic and static acoustic beacons corresponding to claim 1 is a position correction system for multiple underwater vehicles using dynamic and static acoustic beacons, and comprises a static acoustic beacon having a lighthouse acoustic means whose absolute position in an Earth-fixed coordinate system is always known and capable of positioning and / or ranging, an underwater vehicle having a vehicle acoustic means capable of positioning and / or ranging that travels underwater, a position memory means that stores the absolute position of the static acoustic beacon, and a position correction means that corrects the absolute position and relative position, and is characterized in that the position correction means corrects the vehicle absolute position as the absolute position of the underwater vehicle based on the results of positioning and / or ranging of the static acoustic beacon by the vehicle acoustic means and the stored absolute position, and the relative positions of the multiple underwater vehicles are measured by the vehicle acoustic means and / or measured, thereby correcting the relative position of each of the multiple underwater vehicles. According to the present invention as described in claim 1, by combining correction of the absolute position of a vehicle using a static acoustic beacon and correction of the relative position using a dynamic acoustic beacon, it is possible to realize stable underwater observation through group control of multiple underwater vehicles, in which multiple underwater vehicles perform underwater observation while maintaining their relative positional relationships within a certain range.

[0008] The present invention described in claim 2 is characterized in that a specific vehicle among multiple underwater vehicles is designated as a dynamic acoustic beacon, and other vehicles locate and / or measure the position of the dynamic acoustic beacon, thereby correcting the relative positions of the other vehicles. According to the present invention as set forth in claim 2, it is possible to correct the relative positions of the underwater vehicles based on the results of measuring the position of the specific vehicle.

[0009] The present invention as described in claim 3 is characterized in that the positioning information measured by the vehicle acoustic means of the underwater vehicle is the three-dimensional relative position coordinates of the static acoustic lighthouse in the vehicle-fixed coordinate system, or the three-dimensional absolute position coordinates of the static acoustic lighthouse in the Earth-fixed coordinate system. According to the present invention as set forth in claim 3, it is possible to correct the absolute position of the vessel based on the three-dimensional relative position information or three-dimensional absolute position coordinates of the static acoustic lighthouse.

[0010] The present invention as set forth in claim 4 is characterized in that the distance measurement information measured by the vehicle acoustic means of the underwater vehicle is the distance and direction to the dynamic acoustic lighthouse as seen from the underwater vehicle. According to the present invention as set forth in claim 4, an underwater vehicle other than a dynamic acoustic beacon can correct its relative position to the dynamic acoustic beacon based on the distance and direction to the dynamic acoustic beacon as seen from the vehicle itself.

[0011] The present invention as described in claim 5 is characterized in that while the underwater vehicle is correcting its absolute position by positioning and / or ranging relative to a static acoustic beacon, the underwater vehicles share the number of times of absolute position correction by acoustic communication with each other, and the underwater vehicle with the most number of absolute position corrections is determined to be the dynamic acoustic beacon. According to the present invention as set forth in claim 5, it is possible to use underwater vehicles that are considered to have particularly small errors in the absolute position of the vehicle as dynamic acoustic lighthouses to correct the relative positions of underwater vehicles.

[0012] The present invention as set forth in claim 6 is characterized in that the function of the dynamic acoustic lighthouse of a specific underwater vehicle can be replaced by another vehicle. According to the present invention as set forth in claim 6, the role of the dynamic acoustic lighthouse can be switched between underwater vehicles, thereby enabling more complex formation behavior.

[0013] The present invention as set forth in claim 7 is characterized in that the dynamic acoustic beacon constantly measures the position and / or distance of the static acoustic beacon and updates the absolute position of the vessel. According to the present invention as set forth in claim 7, by using the static acoustic beacon to correct the absolute position of the vehicle of the dynamic acoustic beacon even during observation navigation, the deviation of the dynamic acoustic beacon from the target route can be reduced, and the underwater vehicle can be navigated along its respective target route with high accuracy while correcting its relative position using the dynamic acoustic beacon.

[0014] The present invention as described in claim 8 is characterized in that a dynamic acoustic beacon as at least a specific vehicle among a plurality of underwater vehicles performs geometric navigation including straight or circular turns relative to a static acoustic beacon, determines the position and / or distance of the static acoustic beacon, and updates the absolute position of the vehicle. According to the present invention as set forth in claim 8, it becomes possible for an underwater vehicle serving as a dynamic acoustic lighthouse to start observation navigation with a small error in the vehicle's absolute position.

[0015] The present invention as described in claim 9 is characterized in that multiple underwater vehicles are made to sail according to pre-set waypoints, and other vehicles perform positioning and / or ranging to a dynamic acoustic lighthouse as a specific vehicle, and the relative position to the dynamic acoustic lighthouse is updated based on the obtained positioning and ranging information. According to the present invention as set forth in claim 9, underwater vehicles can travel through each waypoint without coming into contact or colliding with each other. Furthermore, by properly maintaining the relative positions of the underwater vehicles, deterioration of observation quality due to mutual interference of acoustic waves between the observation equipment mounted on each underwater vehicle can be prevented, enabling stable underwater observation.

[0016] The present invention as described in claim 10 is characterized in that, based on the updated relative positions, the sailing conditions including the speed of other aircraft relative to the dynamic acoustic lighthouse as a specific aircraft are updated, and the relative positional relationship between multiple underwater vehicles is corrected. According to the present invention as set forth in claim 10, the relative positional relationship between underwater vehicles can be corrected by updating the navigation conditions, thereby enabling safe navigation and stable underwater observation.

[0017] The present invention as defined in claim 11 is characterized in that at least one of the multiple underwater vehicles further has a GPS means capable of floating to the surface of the water and performing global radio positioning, and functions as a specific aircraft or a static acoustic lighthouse. According to the present invention as set forth in claim 11, it is possible to correct the absolute position of another underwater vehicle by using a static acoustic beacon on the water surface, the absolute position of which is known by GPS. Also, it is possible to correct the relative positions of two underwater vehicles by using a specific device that has acquired the absolute position of the vehicle by GPS.

[0018] The present invention as set forth in claim 12 is characterized in that formation control of a plurality of underwater vehicles is performed based on the corrected absolute positions and relative positions of the vehicles. According to the present invention as set forth in claim 12, underwater observation can be performed with high accuracy by a plurality of underwater vehicles controlled in formation. [Effects of the Invention]

[0019] The position correction system for multiple underwater vehicles using dynamic and static acoustic lighthouses of the present invention makes it possible to realize underwater observations by controlling a group of multiple underwater vehicles, in which multiple underwater vehicles perform underwater observations while maintaining their relative positional relationships within a certain range. [Brief explanation of the drawings]

[0020] [Figure 1] Schematic diagram of a system for correcting the position of multiple underwater vehicles using dynamic and static acoustic beacons in one embodiment of the present invention. [Figure 2] Schematic diagram showing an example of a structure installed on the water bottom used as the static acoustic lighthouse [Figure 3] A schematic diagram showing an example in which one of the underwater vehicles is used as a static acoustic lighthouse. [Figure 4] Schematic diagram of underwater acoustic communication between the dynamic acoustic lighthouse and other underwater vehicles. DETAILED DESCRIPTION OF THE INVENTION

[0021] An embodiment of a position correction system for multiple underwater vehicles using dynamic and static acoustic lighthouses (hereinafter, sometimes simply referred to as "position correction system") of the present invention will be described. Figure 1 is a schematic diagram of a position correction system, Figure 2 is a schematic diagram showing an example of using a bottom-mounted structure as a static acoustic beacon, and Figure 3 is a schematic diagram showing an example of using one of the underwater vehicles as a static acoustic beacon. The position correction system comprises an acoustic beacon 10 and an underwater vehicle 20. The acoustic beacon is used to correct the position of the underwater vehicle 20, and is available in two types: a static acoustic beacon 10A and a dynamic acoustic beacon 10B. The static acoustic beacon 10A is installed so that its position in the water is almost fixed. On the other hand, the dynamic acoustic beacon 10B has a navigation means and can navigate together with the underwater vehicle 20.

[0022] Each underwater vehicle 20 is, for example, a sailing type AUV (Autonomous Underwater Vehicle) equipped with navigation means such as a rudders and propellers, and capable of autonomous, unmanned, and untethered navigation. It has acoustic equipment capable of positioning or ranging to an acoustic lighthouse, including a vehicle acoustic means 21 that emits acoustic signals for acoustic positioning or ranging, a position memory means 22 that stores the absolute position of the static acoustic lighthouse 10A, a position correction means 23 that corrects the vehicle's absolute position as its own absolute position and its relative position with respect to other underwater vehicles 20, an inertial navigation system 24 that performs positioning based on the measurement results of various underwater sensors such as an accelerometer and a gyro, a vehicle acoustic communication means 25 used for two-way underwater acoustic wireless communication, and a vehicle acoustic positioning means 26 such as an acoustic transponder that responds to acoustic signals emitted from ships, other underwater vehicles 20, etc.

[0023] Each underwater vehicle 20 estimates its own absolute position, which is the vehicle's absolute position, using an inertial navigation system 24, and navigates while maintaining a predetermined relative positional relationship with other underwater vehicles 20 so as not to come into contact with them. However, as described above, errors occur in the self-position (absolute vehicle position) estimated by each underwater vehicle 20. Therefore, the position correction system corrects the absolute position error and the relative position error that occur in the underwater vehicle 20 by short-range acoustic positioning or ranging with respect to the acoustic lighthouse.

[0024] The static acoustic beacon 10A is defined as a device whose precise absolute position in an Earth-fixed coordinate system is always known, and is used by each underwater vehicle 20 to correct the vehicle's absolute position. The static acoustic lighthouse 10A is equipped with a lighthouse acoustic means 11 such as an acoustic transponder that responds to acoustic signals emitted from the underwater vehicle 20, etc., as acoustic equipment capable of determining position or distance from the underwater vehicle 20. As the static acoustic lighthouse 10A, for example, a water-bottom installation structure provided on the water bottom 1 (see FIG. 2) or an underwater vehicle 20 capable of maintaining its position underwater (see FIG. 3) is used.

[0025] As shown in Figure 2, a water-bottom installation structure that functions as a static acoustic lighthouse 10A includes, for example, a weight 13 that keeps the main body 12 on the water bottom 1, and when it is dropped into the water surface 2 from a ship that has arrived at a designated drop point, it sinks under the weight of the weight 13 and hits the water bottom 1. The weight 13 is configured to be detached by sending a designated sonic signal from the ship, and when the weight 13 is detached, the main body 12 rises to the surface. The absolute position of the bottom-mounted structure that has landed on the bottom is acquired by acoustic positioning or the like from the ship, and the absolute position information of the bottom-mounted structure is input to the underwater vehicle 20 that will perform observation work in the same water area before it is deployed. The input absolute position information is stored in the position storage means 22.

[0026] Figure 3 shows an example of using an underwater vehicle as a static acoustic lighthouse. The underwater vehicle 20 functioning as the static acoustic beacon 10A is equipped with a vehicle acoustic positioning means 26 as the lighthouse acoustic means 11, as well as a GPS (Global Positioning System) means capable of global radio positioning. The underwater vehicle 20 functioning as the static acoustic beacon 10A maintains its position near the water surface 2 with the GPS antenna 14 extended into the air, constantly acquires its own absolute position using the GPS means, and transmits its own absolute position information to other underwater vehicles 20 using the vehicle acoustic communication means 25. The transmitted absolute position information is stored in a position storage means 22. By making the underwater vehicle 20 equipped with a GPS means into a static acoustic beacon 10A, it becomes possible to correct the absolute position of other underwater vehicles 20 by using the static acoustic beacon 10A on the water surface 2 whose absolute position is known, without installing the static acoustic beacon 10A on the water bottom 1.

[0027] Before starting a survey cruise, each underwater vehicle 20 corrects its own absolute position using the static acoustic beacon 10A as follows (see the lower diagram in FIG. 1). Step 1: Dive to the vicinity of the static acoustic lighthouse 10A (underwater structure) located on the water bottom 1, or surface to the vicinity of the static acoustic lighthouse 10A (underwater vehicle 20) located on the water surface 2. In addition, the static acoustic lighthouse 10A (underwater vehicle 20) normally navigates underwater, and when necessary, it rises to the water surface 2, acquires its own absolute position using GPS means, and can also function as a static acoustic lighthouse 10A (underwater vehicle 20). Step 2: After arriving near the static acoustic lighthouse 10A, the vessel performs geometric navigation such as straight sailing and circular turns, while periodically measuring its position or distance to the static acoustic lighthouse 10A using the vessel's acoustic means 21. Step 3: The position correction means 23 estimates the position of the static acoustic beacon 10A by comparing the time series information of positioning or ranging obtained in step 2 with the time series information of positioning or ranging estimated from the geometric navigation, and corrects the absolute position of the own vessel based on the estimated position of the static acoustic beacon 10A and the absolute position information of the static acoustic beacon 10A stored in the position memory means 22.

[0028] By correcting the absolute position of each underwater vehicle 20 before the observation cruise, it becomes possible to start all cruises with little error in the absolute position of the vehicle. The positioning information measured using the vessel acoustic means 21 is preferably the three-dimensional relative position coordinates of the static acoustic beacon 10A in a vessel-fixed coordinate system, or the three-dimensional absolute position coordinates of the static acoustic beacon 10A in an Earth-fixed coordinate system. This makes it possible to correct the vessel absolute position based on the three-dimensional relative position information or three-dimensional absolute position coordinates of the static acoustic beacon 10A.

[0029] FIG. 4 is a schematic diagram of underwater acoustic communication between an underwater vehicle as a dynamic acoustic lighthouse and another underwater vehicle. The dynamic acoustic beacon 10B is used to correct the relative positional relationship between the underwater vehicles 20 during observation navigation. It is not necessary to prepare a dedicated underwater vehicle as the dynamic acoustic beacon 10B; one of the multiple underwater vehicles 20 can be configured to function as the dynamic acoustic beacon 10B. If one of the underwater vehicles 20 is to be the dynamic acoustic beacon 10B, it is possible to determine in advance which underwater vehicle 20 will be the dynamic acoustic beacon 10B before it is deployed, for example, an underwater vehicle 20 that has functioned as a static acoustic beacon 10A can also function as the dynamic acoustic beacon 10B.However, it is preferable to select the underwater vehicle 20 that will be the dynamic acoustic beacon 10B based on the number of times the vehicle's absolute position is corrected before the start of each voyage. When determining the dynamic acoustic beacon 10B based on the number of corrections of the vehicle absolute position, while each underwater vehicle 20 is correcting its absolute position, or after it has completed correcting its absolute position, the underwater vehicles 20 send and receive data via underwater acoustic communication to share the number of absolute position corrections, and the underwater vehicle 20 with the most number of absolute position corrections is determined as the dynamic acoustic beacon 10B. Note that if there are multiple underwater vehicles 20 with the most number of absolute position corrections, one of them is selected as the dynamic acoustic beacon 10B randomly or based on a predetermined rule. As a result, one of the multiple underwater vehicles 20 becomes a specific vehicle that functions as the dynamic acoustic beacon 10B. By determining the dynamic acoustic beacon 10B based on the number of times absolute position correction is performed, it becomes possible to use, among the underwater vehicles 20, an underwater vehicle 20 that is thought to have a particularly small error in the vehicle absolute position as the dynamic acoustic beacon 10B to correct the relative positional relationship between the underwater vehicles 20.

[0030] During observation navigation by a plurality of underwater vehicles 20, the relative positional relationship is appropriately corrected using the dynamic acoustic lighthouse 10B as follows (see the upper diagram in FIG. 1). Step 1: After the absolute position of the vehicle has been corrected, each underwater vehicle 20 navigates according to a preset waypoint list. Step 2: While sailing between waypoints, the underwater vehicles 20 (other vehicles) other than the dynamic acoustic beacon 10B periodically perform positioning or distance measurement with respect to the dynamic acoustic beacon 10B using the vehicle acoustic means 21. Step 3: The underwater vehicles 20 other than the dynamic acoustic beacon 10B calculate their relative positional relationship with the dynamic acoustic beacon 10B using the position correction means 23 from the positioning or ranging information obtained in step 2, and correct their relative position with the dynamic acoustic beacon 10B by changing the sailing conditions, such as changing the target speed or adding waypoints, so that an arbitrary target relative positional relationship is achieved. Step 4: The underwater vehicles 20 other than the dynamic acoustic beacon 10B continue to correct their relative positional relationships with the dynamic acoustic beacon 10B until they reach the final waypoint.

[0031] In this way, the underwater vehicles 20 other than the dynamic acoustic beacon 10B perform positioning or ranging to the dynamic acoustic beacon 10B using the vehicle acoustic means 21, calculate their relative positions to the dynamic acoustic beacon 10B from the acquired positioning or ranging information using the position correction means 23, and correct the relative positions estimated by the inertial navigation system 24 based on the calculated relative positions. This enables the underwater vehicles 20 to navigate through each waypoint without colliding with each other. Furthermore, by maintaining an appropriate distance between the underwater vehicles 20, deterioration of observation quality due to mutual acoustic interference between the observation equipment mounted on each underwater vehicle 20 is prevented, making it possible to perform stable underwater observation. Furthermore, by controlling the formation of each underwater vehicle 20 based on the corrected vehicle absolute position and relative position, it becomes possible to perform underwater observations by multiple underwater vehicles 20 with high accuracy. In addition, the role of the dynamic acoustic lighthouse 10B is performed by one of the underwater vehicles 20, but it is also possible to have the function (role) of the dynamic acoustic lighthouse 10B switched with another underwater vehicle 20 in real time during observation operations according to the waypoint list, thereby making complex formation operations possible.

[0032] Of the multiple underwater vehicles 20, it is preferable that at least the underwater vehicle 20 (specific machine) functioning as the dynamic acoustic beacon 10B estimates the position of the static acoustic beacon 10A and updates the vehicle absolute position by performing geometric navigation such as straight ahead or circular turns relative to the static acoustic beacon 10A before starting an observation navigation with the other underwater vehicles 20. This enables the underwater vehicle 20 as the dynamic acoustic beacon 10B to start an observation navigation with a small error in the absolute position.

[0033] Furthermore, it is preferable that the underwater vehicle 20 functioning as the dynamic acoustic beacon 10B constantly measures the position or distance of the static acoustic beacon 10A even during observation navigation, and updates its own absolute position estimated by the inertial navigation system 24 to a value corrected by the position correction means 23. By correcting the absolute position of the dynamic acoustic beacon 10B and reducing errors even during observation navigation, it is possible to reduce the deviation of the dynamic acoustic beacon 10B from the target route, and ultimately to enable the underwater vehicle 20, which is navigating while correcting the relative positional relationship using the dynamic acoustic beacon 10B, to navigate accurately along each target route.

[0034] The distance measurement information acquired by distance measurement using the underwater vehicle acoustic means 21 is preferably the distance (including response time information from the acoustic beacon) and direction to the dynamic acoustic beacon 10B as seen from the underwater vehicle 20 performing the distance measurement. In this case, the underwater vehicles 20 other than the dynamic acoustic beacon 10B can correct their relative positions to the dynamic acoustic beacon 10B based on the distance and direction to the dynamic acoustic beacon 10B as seen from the underwater vehicle 20 itself.

[0035] As described above, in the position correction system, each underwater vehicle 20 corrects its own absolute position estimated by the inertial navigation system 24 using the position correction means 23 based on the position of the static acoustic lighthouse 10A obtained by positioning and / or ranging using the vehicle acoustic means 21 and the absolute position stored in the position memory means 22, and calculates its relative position with other underwater vehicles 20 based on the results of positioning and / or ranging using the vehicle acoustic means 21, and if there is a deviation from the target, the relative position is corrected using the position correction means 23. By correcting both absolute and relative positions through short-range acoustic positioning or ranging using two types of acoustic lighthouses, dynamic and static, it is possible to realize simultaneous underwater observation by multiple underwater vehicles 20 (underwater observation by controlling a group of multiple vehicles), in which multiple underwater vehicles 20 conduct underwater observation while maintaining their relative positional relationships within a certain range, making stable underwater observation possible. In addition, this position correction system stabilizes the operation of the underwater vehicle 20 and makes it easier to control the underwater vehicle 20 from a surface vessel using acoustic positioning and communications, thereby enabling immediate response in emergencies and flexible changes to observation plans. Furthermore, using this position correction system when conducting underwater observations with multiple underwater vehicles 20 leads to higher quality and stabilization due to the increased amount of observation data. Furthermore, since simultaneous observation at multiple points is possible, observations using sensors that need to maintain the relative positional relationship of the underwater vehicles 20, such as acoustic observations and underwater potential observations, become possible. Furthermore, because this position correction system is based on short-range acoustic positioning or ranging, it can eliminate the disadvantages of long-range acoustic positioning and communication, contributing to reducing acoustic positioning errors, stabilizing acoustic positioning communication, increasing frequency, and reducing delays. In addition, this position correction system combines correction of the absolute position of the vehicle using a static acoustic beacon 10A with correction of the relative positional relationship between underwater vehicles 20 using a dynamic acoustic beacon 10B, thereby enabling more stable underwater observation than before. Furthermore, when correction of the absolute position of the vehicle using the static acoustic beacon 10A is limited to some of the underwater vehicles 20, even if the underwater vehicles 20 other than the dynamic acoustic beacon 10B omit the procedure for correcting their own absolute position, this position correction system can fully ensure safety when multiple underwater vehicles 20 are conducting observation navigation simultaneously by determining the underwater vehicle 20 whose absolute position has been corrected as the dynamic acoustic beacon 10B. [Industrial Applicability]

[0036] This position correction system allows each underwater vehicle to reference a stationary static acoustic beacon and a moving dynamic acoustic beacon using acoustic equipment to determine its position or distance, and then uses the information obtained to correct the vehicle's absolute position and its relative position to other underwater vehicles, thereby achieving underwater observation through the control of a group of multiple vehicles. By using this position correction system, for example, at great depths of approximately 1,000 to 6,000 meters where underwater mineral resources exist, each underwater vehicle can carry out underwater observations with high absolute position estimation accuracy, while properly maintaining its relative position with other underwater vehicles. This enables high-precision underwater observations using sensors that require relative positioning, such as acoustic geological exploration sensors. [Explanation of symbols]

[0037] 2 water surface 10A Static Acoustic Lighthouse 10B Dynamic Acoustic Lighthouse 11 Lighthouse acoustics 20 Underwater vehicle 21 Vehicle acoustic means 22 Position storage means 23 Position correction means

Claims

1. A position correction system for multiple underwater vehicles using dynamic acoustic beacons and static acoustic beacons, a static acoustic lighthouse having a lighthouse acoustic means whose absolute position in an earth-fixed coordinate system is always known and which can be positioned and / or ranged; an underwater vehicle having acoustic means for navigation underwater and capable of positioning and / or ranging, position storage means for storing the absolute position of the static acoustic lighthouse, and position correction means for correcting the absolute position and relative position; A position correction system for multiple underwater vehicles using dynamic and static acoustic lighthouses, characterized in that the position correction means corrects the absolute position of the underwater vehicle as the absolute position of the underwater vehicle based on the results of positioning and / or ranging of the position of the static acoustic lighthouse by the vehicle acoustic means and the stored absolute position, and also positions and / or ranging the relative positions of multiple underwater vehicles using the vehicle acoustic means and corrects the relative position of each of the multiple underwater vehicles.

2. A position correction system for multiple underwater vehicles using dynamic and static acoustic beacons as described in claim 1, characterized in that a specific vehicle among the multiple underwater vehicles is designated as a dynamic acoustic beacon, and other vehicles locate and / or measure the position of the dynamic acoustic beacon, and correct the relative positions of the other vehicles.

3. 2. The position correction system for multiple underwater vehicles using dynamic and static acoustic lighthouses as described in claim 1, characterized in that the positioning information measured by the vehicle acoustic means of the underwater vehicle is the three-dimensional relative position coordinates of the static acoustic lighthouse in a vehicle-fixed coordinate system, or the three-dimensional absolute position coordinates of the static acoustic lighthouse in an Earth-fixed coordinate system.

4. A position correction system for multiple underwater vehicles using dynamic and static acoustic lighthouses as described in claim 1 or claim 2, characterized in that the distance measurement information measured by the vehicle acoustic means of the underwater vehicle is the distance and direction to the dynamic acoustic lighthouse as seen from the underwater vehicle.

5. A position correction system for multiple underwater vehicles using dynamic and static acoustic beacons as described in claim 2, characterized in that while the underwater vehicles are performing absolute position correction of the vehicle by positioning and / or ranging relative to the static acoustic beacon, the underwater vehicles share the number of absolute position corrections by acoustic communication, and the underwater vehicle with the highest number of absolute position corrections is determined to be the dynamic acoustic beacon.

6. A position correction system for multiple underwater vehicles using dynamic and static acoustic beacons as described in claim 2, characterized in that the function of the dynamic acoustic beacon of the specific underwater vehicle is configured to be interchangeable with that of the other underwater vehicles.

7. A position correction system for multiple underwater vehicles using dynamic and static acoustic beacons as described in claim 2, characterized in that the dynamic acoustic beacon constantly measures the position and / or distance of the static acoustic beacon and updates the absolute position of the vehicle.

8. A position correction system for multiple underwater vehicles using dynamic and static acoustic beacons as described in claim 7, characterized in that at least the dynamic acoustic beacon as the specific vehicle among the multiple underwater vehicles performs geometric navigation including straight or circular turns relative to the static acoustic beacon, determines the position and / or distance of the static acoustic beacon, and updates the absolute position of the vehicle.

9. A position correction system for multiple underwater vehicles using dynamic and static acoustic lighthouses as described in claim 2, characterized in that multiple underwater vehicles are made to sail according to pre-set waypoints, the other vehicle performs the positioning and / or ranging to the dynamic acoustic lighthouse as the specific vehicle, and the relative position with the dynamic acoustic lighthouse is updated from the obtained positioning and ranging information.

10. A position correction system for multiple underwater vehicles using dynamic and static acoustic beacons as described in claim 9, characterized in that based on the updated relative position, the sailing conditions including the speed of the other vehicle relative to the dynamic acoustic beacon as the specific vehicle are updated, and the relative positional relationship between the multiple underwater vehicles is corrected.

11. A position correction system for multiple underwater vehicles using dynamic and static acoustic beacons as described in claim 2, characterized in that at least one of the multiple underwater vehicles further has a GPS means that can surface to the water surface and perform global radio positioning, and functions as the specific vehicle or the static acoustic beacon.

12. 2. The position correction system for multiple underwater vehicles using dynamic and static acoustic lighthouses as described in claim 1, characterized in that the formation of the multiple underwater vehicles is controlled based on the corrected absolute positions and relative positions of the vehicles.

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