JP2018036055A - Gravity measurement device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a gravity measurement device that allows a gravity measurement in the water bottom to be stably executed without persons and ropes.SOLUTION: A gravity measurement device, which can autonomously navigate and hover underwater, and grounds the water bottom to measure gravity, comprises: a gravity measurement unit that measures the gravity; a propulsion force generation unit that generates propulsion force so that the gravity measurement device is movable underwater; a laser that irradiates the water bottom with laser light; a camera that photographs the water bottom irradiated with the laser light by the laser; a water bottom shape acquisition unit that acquires a shape of the three-dimensional water bottom on the basis of the image photographed by the camera; a grounding position decision unit that decides a grounding target position of the gravity measurement device on the basis of the shape of the water bottom acquired by the water bottom shape acquisition unit; a grounding control unit that controls the propulsion force generation unit so as to reach the grounding target position decided by the grounding position decision unit, and makes the gravity measurement device ground at the grounding target position; and a posture sensor that detects a change in posture of the gravity measurement device.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a gravity measuring device, and more particularly to a gravity measuring device that measures gravity on the seabed, for example.

  It is known that gravity varies slightly depending on the distance from the measurement point to the center of the earth and the density structure of the underground. It is known to investigate the underground density structure by using this and measuring gravity.

  The invention described in Patent Document 1 discloses a gravity measuring device in which a gravimeter is mounted on a navigation body such as a helicopter and the gravity is measured while flying with the navigation body.

JP 2002-40155 A

  In the gravity measuring device described in Patent Literature 1, the current position is measured by DGPS, and gravity measurement can be performed while flying. However, since this gravity measurement apparatus flies by a navigation body equipped with a gravimeter, there is a problem that it is not suitable for gravity measurement on the bottom of the sea such as the sea bottom, lake bottom or river bottom.

  For example, by measuring gravity at the bottom of the sea, it is possible to explore the underground deposits at the bottom of the sea with high accuracy and contribute to the discovery of seabed resources.

  An object of this invention is to provide the gravity measuring apparatus which can perform the gravity measurement in a water bottom stably without an unmanned search.

  In order to achieve the above-mentioned object, the present invention is a gravity measuring device capable of autonomous navigation and hovering in water and measuring gravity by landing on the bottom of the water, the gravity measuring unit for measuring gravity, and the gravity Photographed by the propulsion generating unit that generates a propulsive force so that the measuring device can move in water, a laser that irradiates the bottom of the laser with laser light, a camera that shoots the bottom of the water irradiated with laser light by the laser, and the camera A bottom shape acquisition unit that acquires a three-dimensional bottom shape based on an image; and a bottom position determination unit that determines a bottom target position of the gravity measuring device based on the bottom shape acquired by the bottom shape acquisition unit; A bottoming control unit for controlling the propulsive force generating unit to reach the bottoming target position determined by the bottoming position determining unit and bottoming the gravity measuring device to the bottoming target position; and the gravity measuring device An attitude sensor for detecting variations in attitude, with a, characterized in that.

  Further, the present invention is a gravity measuring device capable of autonomous navigation and hovering in the water and measuring gravity by landing on the bottom of the water, the gravity measuring unit for measuring gravity, and the gravity measuring device being movable in water Obtained by the propulsive force generating unit that generates the propulsive force, the sonar that measures the water bottom topography, the water bottom shape obtaining unit that obtains the three-dimensional water bottom shape based on the measurement result by the sonar, and the water bottom shape obtaining unit A bottom position determining unit that determines a target bottom position of the gravity measuring device based on the shape of the bottom, and the propulsive force generation unit is controlled to reach the target bottom position determined by the bottom position determining unit. And a bottoming control unit that bottoms the gravity measuring device at the bottoming target position, and a posture sensor that detects a change in posture of the gravity measuring device.

  ADVANTAGE OF THE INVENTION According to this invention, the gravity measuring apparatus which can perform the gravity measurement in a water bottom stably without an unmanned can be provided.

It is a left view of the gravity measuring apparatus which concerns on one Embodiment of this invention. It is a front view of the gravity measuring apparatus shown in FIG. It is a bottom view of the gravity measuring apparatus shown in FIG. It is a schematic block diagram of the gravity measuring apparatus shown in FIG. It is a flowchart which shows an example of operation | movement of the gravity measuring apparatus shown in FIG. It is a figure explaining an example of operation | movement of the gravity measuring apparatus shown in FIG.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  1 is a left side view of a gravity measuring device according to an embodiment of the present invention, FIG. 2 is a front view of the gravity measuring device shown in FIG. 1, and FIG. 3 is a gravity shown in FIG. It is a bottom view of a measuring device.

  The gravity measuring apparatus 100 of the present embodiment mainly includes a main container 6 that houses various control boards and the like, a battery container 7 that houses a battery 115 (see FIG. 4) that is a power source for operating the gravity measuring apparatus 100, and And a spherical container 10 containing a gravimeter 111 (see FIG. 4) for measuring gravity. Although described in detail later, the gravity measuring device 100 is configured to be capable of navigating in water, and reaches the bottom of the water and performs gravity measurement with the gravimeter 111. The gravity measuring device 100 can measure gravity by landing on the bottom of a seabed, a lake bottom, a riverbed, or the like. Hereinafter, an example of landing on the seabed will be described. The main container 6, the battery container 7, and the spherical container 10 are waterproofed so that seawater does not enter the interior, and are pressure-resistant processed to withstand water pressure.

  The gravimeter 111 is accommodated in the spherical container 10 and is configured to be kept horizontal by a gimbal mechanism (not shown), for example. By maintaining the level of the gravimeter 111, it is ensured that the gravity measured by the gravimeter 111 is vertical gravity. The gravimeter 111 is supported by the gimbal mechanism. However, when the level cannot be maintained completely or when there is another external factor, the measurement result by the gravimeter 111 may be corrected accordingly.

  The spherical container 10 containing the gravimeter 111 is fixed to the skid 11 which is a load receiving table, and is provided at the lower center of the gravity measuring device 100. In addition, a ballast releaser 110, a Doppler ground speedometer 12, and a CTD 15 are provided at the lower part of the gravity measuring apparatus 100. The CTD 15 is a device that measures electrical conductivity (conductivity) (= salinity), temperature (Temperature), and depth (Depth) of the surrounding seawater. From the CTD data measured by the CTD15, the density and accurate of the seawater are measured. Depth can be calculated. By using this CTD data, the gravity measured by the gravimeter 111 can be corrected accurately. The CTD data is stored in the CTD 15 together with the measurement time, for example.

  A wireless LAN antenna 1 is provided on the upper part of the gravity measuring device 100, and data communication via the wireless LAN is performed with the wireless LAN communication device 103 (see FIG. 4) in the main container 6 via the wireless LAN antenna 1. It is feasible.

  In addition, a GPS antenna 2 is provided adjacent to the wireless LAN antenna 1 on the upper part of the gravity measuring device 100, and the GPS device 105 (see FIG. 4) in the main container 6 is not connected via the GPS antenna 2. By receiving GPS signals from the GPS satellites shown, the position of the gravity measuring device 100 on the water surface can be specified.

  Furthermore, in the center of the upper part of the gravity measuring device 100, one transmitting antenna 3 and four receiving antennas 4 used in the acoustic positioning communication device 104 (see FIG. 4) in the main container 6 that enables data communication by sound. Is provided. When the gravity measuring apparatus 100 is on the sea, the wireless LAN communication apparatus 103 can communicate with the outside such as a ship on the sea. However, when the gravity measuring device 100 is submerged in the sea, communication by the wireless LAN communication device 103 becomes difficult. Therefore, in the present embodiment, the acoustic measurement communication device 104 is provided in the gravity measurement device 100 so that the gravity measurement device 100 in the sea can communicate with the outside such as a ship on the sea.

  The gravity measuring device 100 is provided with a thruster 108 (see FIG. 4) that generates a propulsive force so that the gravity measuring device 100 can move in the sea. The thruster 108 of this embodiment is a propeller-like member, and includes two surge thrusters 5a that generate a propulsive force in the front-rear direction, one swath thruster 5b that generates a propulsive force in the left-right direction, and propulsion in the vertical direction. Two heave thrusters 5c for generating force. By switching the rotation start, rotation stop, rotation direction and rotation speed of the propellers of these two surge thrusters 5a, one sway thruster 5b and two heave thrusters 5c, the gravity measuring device 100 can be moved freely. is there.

  In the gravity measuring device 100, a buoyancy material 13 is provided around the main container 6. Further, the gravity measuring device 100 is provided with a ballast (not shown) (weight for balancing buoyancy), and when all the thrusters 108 are stopped, the gravity measuring device 100 is in a bottomed state. Further, when the ballast is released (discarded) by the ballast trimmer 110 (see FIG. 4), the gravity measuring device 100 floats on the sea surface due to the buoyancy of the buoyancy material 13.

  A laser 8 capable of irradiating the bottom of the sea with laser light is provided at the bottom of the battery container 7 of the gravity measuring device 100, and the bottom of the gravity measuring device 100 can photograph the sea bottom irradiated with laser light with the laser 8. A camera 14 is provided. The laser 8 irradiates a linear laser beam onto the seabed, and an image thereof is taken by the camera 14, and a three-dimensional shape of the seabed can be obtained by, for example, a light cutting method. In the present embodiment, the three-dimensional shape of the seabed is obtained by the light cutting method, but the present invention is not limited to this, and any known method may be used.

  FIG. 4 is a schematic block diagram of the gravity measuring apparatus shown in FIG.

  The control device 101 in FIG. 4 includes, for example, a calculation device called a CPU or MPU and is accommodated in the main container 6. The operation control of the gravity measuring device 100 is performed by the control device 101. The storage device 102 is a storage device such as a RAM or a ROM, and includes a nonvolatile storage device, and stores a program executed by the control device 101 for operating the gravity measuring device 100 and various data. The storage device 102 may store various measurement data in association with the time and position acquired by the GPS device 105. Further, the control device 101 may have a clock (not shown). When the time cannot be obtained by the GPS device 105 because it is underwater, the control device 101 is associated with the time acquired by the clock of the control device 101. Various measurement data may be stored in the storage device 102. In addition, by installing a station (not shown) on the seabed in advance, the relative position of the gravity measuring device 100 with respect to the station can be acquired using the acoustic positioning communication device 104. When the position cannot be obtained by the GPS device 105 because it is underwater, the relative position obtained by the acoustic positioning communication device 104 is stored in the storage device 102 in association with the time and various measurement data. Also good.

  The control device 101 operates according to a program stored in advance in the storage device 102 and controls each part of the gravity measuring device 100. The control device 101 can also control each unit of the gravity measurement device 100 by remote operation according to an operation instruction obtained via the wireless LAN communication device 103 or the acoustic positioning communication device 104.

  The camera 106 includes the camera 14 shown in FIG. 3, and includes other cameras (not shown) (for example, other cameras for photographing the seabed, other cameras for photographing the periphery of the gravity measuring device 100). Also good. The camera 106 captures an image according to an instruction from the control device 101, sends the captured image (or video) to the control device 101, and the control device 101 that receives the image stores the image in the storage device 102.

  The laser 107 includes the laser 8 shown in FIG. 1 and may include another laser (not shown) (for example, a laser different from the laser 8). The laser 107 irradiates laser light according to an instruction from the control device 101.

  The camera 106 and the laser 107 may instead be a sonar (not shown).

  The thruster 108 switches the propeller rotation start, rotation stop, rotation direction, and rotation speed according to an instruction from the control device 101. In this embodiment, the directions of the surge thruster 5a, sway thruster 5b, and heave thruster 5c are fixed, but they may be changed to arbitrary directions according to instructions from the control device 101.

  The sensor 109 includes a Doppler type ground speed meter (DVL) 12 that measures ground speed, a fiber optic gyro (FOG) that measures azimuth speed (not shown), and a pressure gauge that measures water depth (not shown). ), An anemometer (not shown), an attitude sensor (not shown), and the like, operate according to instructions from the control device 101, and transmit measurement results and detection results to the control device 101. Note that a magnetic compass is attached to the attitude sensor and the DVL. Further, by replacing the optical fiber gyroscope and the attitude sensor with an inertial navigation system (Internal Navigation System, INS), more accurate position / attitude data can be obtained. In addition, the sensor 109 is equipped with a scanning sonar (not shown) for obstacle detection, and further equipped with a flasher (not shown) and a transponder (not shown) as safety measures when operating in the actual sea area. To do.

  The ballast trilator 110 releases (discards) the ballast described above in response to an instruction from the control device 101.

  The gravimeter 111 always measures gravity and transmits the measurement result to the storage device 112. The storage device 112 may start the storage of the gravity measurement result and stop the storage of the measurement result in response to an instruction from the control device 101, or may be a program stored in advance in the storage device 112. The measurement result of gravity may be stored in accordance with the measurement result, the measurement result may be transmitted to the control device 101, and errors and other operating conditions during measurement may be stored in the control device 101. You may transmit. The storage device 112 is a device called a data logger, for example.

  The battery 115 supplies power to each component of the gravity measuring device 100. However, the gravimeter 111 and the storage device 112 need to be constantly energized (for example, the gravimeter 111 needs to be measured in an environment where the ambient temperature is kept constant, and is always energized for the thermostatic chamber that houses the gravimeter 111. Therefore, power is supplied from a dedicated battery 113. The gravity meter 111, the storage device 112, and the battery 113 constitute a gravity measuring unit 114.

  FIG. 5 is a flowchart showing an example of the operation of the gravity measuring apparatus shown in FIG.

  First, the gravity measuring device 100 is placed on a ship or the like, proceeds on the sea, is carried to the area where gravity measurement is performed, and the gravity measuring device 100 is lowered to the sea surface. The gravity measuring device 100 can autonomously sail and hover in the sea by driving the thruster 108, and the thruster 108 is stopped due to the buoyancy balance between the weight of the gravity measuring device 100, the buoyant material 13 and the above-described ballast. In the state, it is configured to have negative buoyancy so as to be stable on the seabed. Note that the present invention is not limited to this, and neutral buoyancy may be used, and downward thrust may be continued by the heave thruster 5c at the time of bottoming. For example, buoyancy may be adjusted by a buoyancy adjustment device (not shown). May be.

  Thereafter, for example, when the gravity measuring device 100 is on the sea, an operator on the ship operates a terminal device (not shown) and the like, and remotely operates the gravity measuring device 100 via the wireless LAN antenna 1 and the wireless LAN communication device 103. To instruct execution of the processing of FIG. In response to this, in the gravity measuring device 100, the program stored in advance in the storage device 102 is executed by the control device 101, and the processing shown in the flowchart of FIG. 5 is automatically executed. Further, when the gravity measuring device 100 is in the sea, remote operation via the acoustic positioning communication device 104 is also possible.

  The control device 101 analyzes the sea bottom image captured by the camera 106 based on the measurement result and detection result of the sensor 109, and based on the positioning result of the acoustic positioning communication device 104. The thruster 108 is driven so as to dive and reach a predetermined landing area (steps S-0 and S-1). One or more bottoming areas are stored in advance in the storage device 102, one of the bottoming areas is selected, and gravity is sequentially measured in each bottoming area as will be described later.

  Subsequently, when the gravity measuring device 100 reaches the landing area, the control device 101 irradiates the sea bottom with a line-shaped laser beam with the laser 8 and also images the sea bottom irradiated with the laser beam with the camera 14. Using the captured image, a three-dimensional shape of the seabed is obtained by, for example, a light cutting method (step S-2). In the case where a sonar is provided instead of the laser 8 and the camera 14, in step S-2, the seabed topography is measured by the sonar, and a three-dimensional seabed shape is acquired based on the measurement result by the sonar. You may do it.

  Subsequently, the control device 101 refers to the three-dimensional shape of the seabed acquired in step S-2, and determines the landing point, that is, the landing target position (step S-3). As the bottoming target position, a position where the gravity measuring device 100 having a small unevenness and a small inclination (an angle as close to the horizontal as possible) can be settled is selected and determined.

  If the bottoming target position is determined, the control device 101 drives the thruster 108 to bottom the gravity measuring device 100 at the bottoming target position (step S-4). For example, the gravity measuring apparatus 100 measures the flow direction with the velocimeter of the sensor 109 in a state of being stationary with respect to the sea bottom, and faces the direction directly opposite the flow. While maintaining the azimuth, for example, while measuring the altitude and the ground speed from the seabed by the Doppler type ground speedometer 12 of the sensor 109, the thrust of the Heave thruster 5c is lowered, and the ground is landed as it is. When the bottoming is completed, the thruster 108 (that is, all thrusters of the surge thruster 5a, the sway thruster 5b, and the heave thruster 5c) is stopped.

  Thereafter, the control device 101 monitors the posture of the gravity measuring device 100 by a posture sensor of the sensor 109 for a certain time (for example, several seconds to several minutes) (step S-5), and when there is no change in posture (step S-). 5: Yes), the bottoming is continued as it is, and the gravity measurement by the gravimeter 111 is executed (step S-6). The measurement result is stored in the storage device 102 or 112.

  If there is a change in posture in Step S-5 (Step S-5: No), the process returns to Step S-1 and starts again from the selection of the bottom target position.

  If gravity measurement is completed in step S-6, it is determined whether gravity measurement has been completed in all landing areas stored in advance in the storage device 102 (step S-7). (Step S-7: No), returning to Step S-1, the gravity measurement in the new landing area is performed. If completed (step S-7: Yes), the process proceeds to step S-8 and ascends to the sea surface. At this time, the control apparatus 101 can drive the thruster and release the ballast by the ballast trimmer 110 to increase the buoyancy and to increase the buoyancy, thereby increasing the ascent speed.

  FIG. 6 is a diagram for explaining an example of the operation of the gravity measuring apparatus shown in FIG. The example of FIG. 6 shows a case where the gravity measuring device 100 performs gravity measurement at the points A, B, C, and D.

  In this example, the gravity measuring apparatus 100 first executes the processes of steps S-1 to S-7 in FIG. 5 at point A, and then performs the processes of steps S-1 to S-7 in FIG. 5, subsequently, the process of steps S-1 to S-7 in FIG. 5 is executed at the point C, the process of steps S-1 to S-7 in FIG. 5 is subsequently executed at the point D, and finally, As blockage measurement, it returns to A point (starting point), performs the process of step S-1 to S-7 of FIG. 5 at A point, and then floats to the sea surface by the process of step S-8 of FIG.

  Comparing the results of gravity measurements at points A to D, the gravity at points B and C is greater than the gravity at points A and D, and the material is denser than the surroundings from point B to point C. (For example, hydrothermal deposits) may exist.

  According to the present embodiment, by obtaining the three-dimensional shape of the seabed and determining the landing target position based on the three-dimensional shape of the seabed, the gravity measuring device can be safely and stably settled. Gravity measurement at can be made possible.

  Further, according to the present embodiment, gravity measurement can be performed on the seabed, and gravity can be measured with higher accuracy than in the case of measurement in the air, on the sea, and in the sea.

  In addition, according to the present embodiment, it is possible to execute a series of gravity measurement processes by operating according to a program stored in advance in the storage device 102. For example, it is necessary to be connected to a marine ship by wire. In addition, it is possible to measure gravity at deeper seabed.

<Appendix 1>
In the present invention,
1.
A gravity measuring device (for example, the gravity measuring device 100) that is capable of autonomous navigation and hovering in the water and that measures gravity by landing on the bottom of the water,
A gravity measurement unit (for example, a gravity measurement unit 114) that measures gravity;
A propulsive force generator (e.g., thruster 108) that generates a propulsive force so that the gravity measuring device can move in water;
A laser that irradiates the bottom of the laser with laser light (for example, laser 107);
A camera (e.g., camera 106) that captures the bottom of the water irradiated with laser light from the laser;
A water bottom shape acquisition unit (for example, the control device 101) that acquires a three-dimensional water bottom shape based on an image captured by the camera;
A bottom position determination unit (for example, the control device 101) that determines a bottom target position of the gravity measuring device based on the bottom shape acquired by the bottom shape acquisition unit;
A bottoming control unit (for example, the control device 101) that controls the propulsive force generation unit to reach the bottoming target position determined by the bottoming position determination unit and bottoms the gravity measuring device at the bottoming target position. )When,
A posture sensor (for example, a posture sensor included in the sensor 109) for detecting a change in posture of the gravity measuring device;
With
Because it is a gravity measuring device, characterized by
It is possible to provide a gravity measuring device capable of performing unsteady and stable gravity measurement at the bottom of the water.

The present invention also provides
2.
A gravity measuring device capable of autonomous navigation and hovering in the water, and measuring gravity by landing on the bottom of the water,
A gravity measurement unit for measuring gravity;
A propulsive force generating section for generating a propulsive force so that the gravity measuring device can move underwater;
A sonar that measures underwater topography,
A water bottom shape acquisition unit for acquiring a three-dimensional water bottom shape based on a measurement result by the sonar;
A bottom position determination unit that determines a bottom target position of the gravity measuring device based on the bottom shape acquired by the bottom shape acquisition unit;
A bottoming control unit that controls the propulsive force generation unit to reach the bottoming target position determined by the bottoming position determination unit, and bottoms the gravity measuring device at the bottoming target position;
A posture sensor for detecting a change in posture of the gravity measuring device;
With
Because it is a gravity measuring device, characterized by
It is possible to provide a gravity measuring device capable of performing unsteady and stable gravity measurement at the bottom of the water.

The present invention also provides
3.
1. Or 2. In the gravity measuring device described in
The bottoming position determination unit changes the bottoming target position and determines a new bottoming target position when there is a change in the posture detected by the posture sensor in a state where the gravity measuring device is bottomed.
It was set as the gravity measuring device characterized by this.

  The embodiments of the present invention are not limited to the individual embodiments described above, and any combination of elements of the individual embodiments is included in the present invention, and various modifications that can be conceived by those skilled in the art are also included. Thus, the effects of the present invention are not limited to the above-described contents. That is, various additions, modifications, and partial deletions can be made without departing from the concept and spirit of the present invention derived from the contents defined in the claims and equivalents thereof.

  DESCRIPTION OF SYMBOLS 1 ... Wireless LAN antenna, 2 ... GPS antenna, 3 ... Transmission antenna, 4 ... Reception antenna, 5a ... Surge thruster, 5b ... Sway thruster, 5c ... Heave thruster, 6 ... Main container, 7 ... Battery container, 8 ... Laser, DESCRIPTION OF SYMBOLS 10 ... Spherical container, 11 ... Skid, 12 ... Doppler type ground speedometer, 13 ... Buoyancy material, 14 ... Camera, 15 ... CTD, 110 ... Ballast rillisa

Claims (3)

A gravity measuring device capable of autonomous navigation and hovering in the water, and measuring gravity by landing on the bottom of the water,
A gravity measurement unit for measuring gravity;
A propulsive force generating section for generating a propulsive force so that the gravity measuring device can move underwater;
A laser that irradiates the bottom of the laser with laser light;
A camera for photographing the bottom of the water irradiated with laser light from the laser;
A water bottom shape acquisition unit for acquiring a three-dimensional water bottom shape based on an image photographed by the camera;
A bottom position determination unit that determines a bottom target position of the gravity measuring device based on the bottom shape acquired by the bottom shape acquisition unit;
A bottoming control unit that controls the propulsive force generation unit to reach the bottoming target position determined by the bottoming position determination unit, and bottoms the gravity measuring device at the bottoming target position;
A posture sensor for detecting a change in posture of the gravity measuring device;
With
Gravity measuring device characterized by that. A gravity measuring device capable of autonomous navigation and hovering in the water, and measuring gravity by landing on the bottom of the water,
A gravity measurement unit for measuring gravity;
A propulsive force generating section for generating a propulsive force so that the gravity measuring device can move underwater;
A sonar that measures underwater topography,
A water bottom shape acquisition unit for acquiring a three-dimensional water bottom shape based on a measurement result by the sonar;
A bottom position determination unit that determines a bottom target position of the gravity measuring device based on the bottom shape acquired by the bottom shape acquisition unit;
A bottoming control unit that controls the propulsive force generation unit to reach the bottoming target position determined by the bottoming position determination unit, and bottoms the gravity measuring device at the bottoming target position;
A posture sensor for detecting a change in posture of the gravity measuring device;
With
Gravity measuring device characterized by that. In the gravity measuring device according to claim 1 or 2,
The bottoming position determination unit changes the bottoming target position and determines a new bottoming target position when there is a change in the posture detected by the posture sensor in a state where the gravity measuring device is bottomed.
Gravity measuring device characterized by that.