Position control system for underwater device

Abstract

The purpose of the present invention is to provide an underwater device capable of controlling the underwater position thereof without using a tether, a control system for the same, and a control method for the same.　An underwater device control system according to the present invention comprises: a master machine 20 having a transmitter-receiver 21 for underwater optical communication and a single optical pointer 22; and an underwater device 10 that is movable in water and that performs the underwater optical communication with the master machine 20. The master machine 20 emits light Lp of the optical pointer 22 sequentially so as to surround a range Asig in which the underwater optical communication can be performed and while changing the wavelength of the light Lp. The wavelength of the light Lp of the optical pointer 22 is determined by a position with respect to the range Asig. The underwater device 10 comprises a drive unit 30 that moves the underwater device 10 in accordance with a control direction correspondence table on the basis of the wavelength of the light Lp identified by a detection unit.

Description

Underwater equipment position control system

[0001] The present disclosure relates to an underwater device capable of controlling its position in water, a control system therefor, and a control method therefor.

[0002] In recent years, while aerial drones have been under consideration for social implementation, underwater drones are being developed with the aim of innovating in the underwater field. Aerial drones can be controlled wirelessly using radio waves, and location information can be obtained using satellite positioning systems (such as GNSS), so they are being applied to delivery systems using GPS, for example.

[0003] On the other hand, underwater, the transmission characteristics of various physical media are significantly limited compared to air, and the signals of the satellite positioning system required for control use radio waves, which cannot reach underwater, making it difficult to obtain position information. For this reason, current underwater drones are controlled by an operator on board a ship via a cable called a tether (see, for example, Non-Patent Document 1).

[0004] Masaki Minami, "Current Status and Issues of Underwater Drone Systems," Measurement and Control, Vol. 59, No. 7, 2020, pp. 492-496.

[0005] Controlling via such a tether poses the following tether-related challenges: (Challenge 1) Multiple skilled personnel are required for operation, such as pilots and cable operators, which poses the challenge of securing personnel. (Challenge 2) It is necessary to avoid the risk of the underwater drone itself becoming tangled in the tether cable and becoming unable to navigate, which poses the challenge of risk avoidance control. (Challenge 3) There is a challenge in that navigation in narrow spaces is difficult due to the risk of the tether cable becoming tangled in obstacles, which limits the navigation area. (Challenge 4) There is a challenge in that the navigation range is limited to the length of the tether cable.

[0006] Therefore, in order to solve the above problems, an object of the present invention is to provide a master unit capable of controlling the position of underwater equipment without using a tether, a control system for the master unit, and a control method for the master unit.

[0007] In order to achieve the above-mentioned objective, the control system for underwater equipment of the present invention is configured to emit light from an optical pointer so as to surround an area in which underwater optical communication can be performed from the control side, and to give the underwater equipment the ability to move autonomously so as to stay within the area surrounded by the optical pointer.

[0008] Specifically, the underwater equipment control system of the present invention comprises: a parent unit having a transceiver for underwater optical communication and a single optical pointer; and underwater equipment that is movable underwater and performs underwater optical communication with the parent unit, wherein the parent unit sequentially irradiates the light of the optical pointer while changing the wavelength so as to surround a range in which underwater optical communication is possible, and the wavelength of the light of the optical pointer is determined by its position relative to the range, and the underwater equipment comprises: a detection unit that detects the light of the optical pointer; a control direction correspondence table in which the direction to move for the wavelength of light is set; a determination unit that identifies the wavelength of light detected by the detection unit; and a control unit that moves the underwater equipment in accordance with the control direction correspondence table based on the wavelength of light identified by the determination unit.

[0009] Furthermore, the underwater equipment control method of the present invention is a method for controlling the position of underwater equipment that is movable underwater and performs underwater optical communication with a parent unit having a transceiver for underwater optical communication and a single optical pointer, wherein the parent unit: sequentially irradiates the light of the optical pointer while changing the wavelength so as to surround a range in which underwater optical communication is possible, and the wavelength of the light of the optical pointer is determined by its position relative to the range; and the underwater equipment has a control direction correspondence table in which the direction in which the underwater equipment should move relative to the wavelength of the light of the optical pointer is set; detects the light of the optical pointer, identifies the wavelength of the detected light, and moves the underwater equipment in accordance with the control direction correspondence table based on the identified wavelength.

[0010] The parent unit of the present invention is a parent unit that performs underwater optical communication with underwater equipment that is movable underwater, and has a transceiver for the underwater optical communication and a single optical pointer, and is characterized in that the optical pointer sequentially irradiates light with changing wavelengths to surround a range in which the underwater optical communication is possible, and the wavelength of the light is determined by its position relative to the range.

[0011] This underwater device control system can keep the underwater device within the area surrounded by the optical pointer. Therefore, the present invention can provide an underwater device that can control its position underwater without using a tether, a control system for the same, and a control method for the same.

[0012] Here, the optical pointer may provide a switching time during which the light is not emitted when the wavelength is changed, or may provide an overlap time during which the wavelength before and after the change overlap when the wavelength is changed.

[0013] The above inventions can be combined as much as possible.

[0014] The present invention can provide a master unit capable of controlling the position of an underwater device without using a tether, a control system therefor, and a control method therefor.

[0015] FIG. 1 is a table summarizing the characteristics of each communication medium. FIG. 2 is a diagram illustrating an underwater equipment control system according to the present invention. FIG. 3 is a diagram illustrating an underwater equipment control method according to the present invention. FIG. 4 is a diagram illustrating an optical pointer of the underwater equipment control system according to the present invention. FIG. 5 is a diagram illustrating an optical pointer of the underwater equipment control system according to the present invention. FIG. 6 is a diagram illustrating a range of light emitted by an optical pointer of the underwater equipment control system according to the present invention. FIG. 7 is a diagram illustrating the timing of light emission by an optical pointer of the underwater equipment control system according to the present invention. FIG. 8 is a diagram illustrating a control direction correspondence table provided in the underwater equipment according to the present invention. FIG. 9 is a diagram illustrating the range of light emitted by an optical pointer of the underwater equipment control system according to the present invention. FIG. 10 is a diagram illustrating the timing of light emission by an optical pointer of the underwater equipment control system according to the present invention. FIG. 11 is a diagram illustrating a control direction correspondence table provided in the underwater equipment according to the present invention. FIG. 12 is a diagram illustrating an underwater equipment according to the present invention. FIG. 13 is a diagram illustrating an underwater equipment according to the present invention.

[0016] The following description of the preferred embodiments of the present invention will be given with reference to the accompanying drawings. The preferred embodiments described below are examples of the present invention, and the present invention is not limited to the preferred embodiments. In this specification and the drawings, components having the same reference numerals are intended to represent the same components.

[0017] (Purpose) To resolve the aforementioned issues with current underwater drones requiring tethers, it is necessary to establish a means of communication between the operator and the underwater drone. Figure 1 summarizes the underwater characteristics and issues of each physical medium: sound, light, and radio waves. Considering applications such as transmitting high-definition video from underwater industrial robots, underwater communication using light is an attractive method. However, because light is highly directional and travels in a straight line even underwater, it is necessary to control the underwater drone within the range where optical communication is possible. However, as shown in Figure 1, GNSS signals and control signals, which use radio waves, are absorbed by water and are therefore unsuitable for controlling underwater drones. For this reason, some method is required to autonomously control underwater drones.

[0018] In the control system of this embodiment, to achieve the above-mentioned problem of autonomously controlling the position of the underwater drone within the range where optical communication is possible, a wavelength-dependent optical pointer is used to perform vertical and horizontal position correction. The main features of this control system are as follows: (1) An optical pointer with a wavelength different from the underwater optical communication wavelength is controlled by mechanical or optical control to control the irradiation direction and irradiation range, and the light is irradiated so as to encompass the range where underwater optical communication is possible. (2) The optical pointer can output light of multiple wavelengths. (3) When the underwater drone detects the optical pointer, it determines the direction of movement based on the wavelength of the detected pointer (autonomous control). (4) If the underwater drone can no longer detect the optical pointer, it moves (translation, vertical movement, rotation, etc.) to search for the optical pointer. If the underwater drone detects the optical pointer again, it resumes autonomous control from that point.

[0019] 2 is a diagram illustrating an underwater equipment control system according to this embodiment. The underwater equipment control system comprises: a master unit 20 having a transceiver 21 for underwater optical communication and a single optical pointer 22; and an underwater equipment 10 movable underwater and performing the underwater optical communication with the master unit 20. The master unit 20 sequentially irradiates light Lp of the optical pointer 22 while changing the wavelength so as to surround an area Asig in which the underwater optical communication is possible, and the wavelength of the light Lp of the optical pointer 22 is determined by its position relative to the area Asig. The underwater equipment 10 comprises: a detector 11 that detects the light Lp of the optical pointer 22; a control direction correspondence table in which the direction to move relative to the wavelength of the light Lp is set; a determiner that identifies the wavelength of the light Lp detected by the detector; and a driver 30 that moves the underwater equipment 10 in accordance with the control direction correspondence table based on the wavelength of the light Lp identified by the detector.

[0020] If the underwater device 10 moves left and right or forward and backward relative to the parent device 20, the optical signal transmitting and receiving unit of the underwater device 10 will move out of the range Asig where underwater optical communication is possible, making it impossible to communicate with the parent device 20. To avoid this, the underwater device control system performs autonomous position control of the underwater device using a preset control direction correspondence table (movement direction relative to the wavelength of light) and the detected wavelength of light of the optical pointer (see Figure 3).

[0021] In other words, this underwater device control method is a control method for controlling the position of an underwater device 10 that is movable underwater and performs underwater optical communication with a master device 20, using a master device 20 having a transceiver 21 for underwater optical communication and a single optical pointer 22. First, the master device 20 sequentially irradiates light Lp of the optical pointer 22 while changing the wavelength so as to surround a range Asig where underwater optical communication is possible (step S01). At this time, the wavelength of the light Lp of the optical pointer 22 is determined by its position relative to the range Asig. Here, the underwater device 10 has a control direction correspondence table in which the direction to move is set for the wavelength of the light Lp of the optical pointer 10. Then, the underwater device 10 detects the light of the optical pointer 10 ("Yes" in step S02), identifies the wavelength of the detected light, and moves the underwater device based on the identified wavelength and in accordance with the control direction correspondence table (step S03).

[0022] After step S03, or when the underwater device 10 cannot detect the light Lp of the optical pointer 22 ("No" in step S02), it is confirmed whether the underwater device 10 can receive the optical signal Lsig of underwater optical communication (step S04). If the underwater device 10 can receive the optical signal Lsig of underwater optical communication ("Yes" in step S04), the process from step S02 is repeated.

[0023] On the other hand, if the underwater equipment 10 cannot receive the optical signal Lsig of underwater optical communication ("No" in step S04), the underwater equipment 10 moves a predetermined distance toward the sea surface (surfaces a predetermined amount) (step S05) and again checks whether it can receive the optical signal Lsig of underwater optical communication (step S06).

[0024] If the underwater device 10 can receive the optical signal Lsig of underwater optical communication ("Yes" in step S06), the process from step S02 is repeated. On the other hand, if the underwater device 10 cannot receive the optical signal Lsig of underwater optical communication ("No" in step S06), the underwater device 10 is moved or its posture is changed until the detection unit can detect the light Lp of the optical pointer (step S07). Then, the process from step S02 is repeated.

[0025] If the answer is "Yes" in step S04 or S06, the control flow in Fig. 3 may be terminated at that point. In this case, it is preferable to periodically execute the control flow.

[0026] (Example 1) A specific example will be described with reference to Figures 4 to 7. Figure 4 is a diagram illustrating the arrangement of the optical signal transceiver 21 and the optical pointer 22 in the master unit 20 (e.g., the bottom of a ship). Figure 5 is a diagram illustrating the structure of the optical pointer 22. Figure 5(Ax) is a diagram illustrating the structure and operation of the optical pointer 22 that mechanically controls the emission direction of light Lp. The pointer 22 includes a light source 22a that emits light Lp and a direction control unit 22b that changes the direction. The direction control unit 22b changes the direction of the light source 22a, thereby changing the emission direction of the light Lp. Figure 5(Bx) is a diagram illustrating the structure and operation of the optical pointer 22 that optically controls the emission direction of the light Lp. The pointer 22 includes an optical element 22c that emits light Lp and a direction control unit 22d that changes the direction. The direction control unit 22d changes the direction of the optical element 22c, thereby changing the emission direction of the light Lp. The beam system (emitting end of the light Lp) of the light pointer 22 may be configured to combine a light source and an optical system to limit the irradiation range to a square area or the like.

[0027] The optical pointer 22 outputs light Lp of multiple specified wavelengths. The optical pointer 22 is placed at a position on the parent unit 20 where it can irradiate light Lp so as to surround the range Asig where underwater optical communication is possible. The parent unit 20 controls the movement of the underwater drone in a direction according to the preset wavelength of light Lp. The underwater drone may detect light Lp using color information from image recognition or light wavelength information.

[0028] FIG. 6 is a diagram illustrating the irradiation ranges (Ap1 to Ap4) of light Lp from the optical pointer 22. The light Lp emitted by the optical pointer 22 has a different wavelength for each range (Ap1 to Ap4). In this example, there are four irradiation ranges, so there are four wavelengths of light. The optical pointer 22 emits light Lp so that the irradiation ranges (Ap1 to Ap4) surround the underwater optical communication range Asig. The size of the irradiation ranges (Ap1 to Ap4) may be adjusted as desired using a lens or the like. Furthermore, although the irradiation ranges (Ap1 to Ap4) are circular in FIG. 6, they may also be adjusted to a polygonal shape using an optical system.

[0029] 7, the optical pointer 22 switches the illumination range (Ap1 to Ap4) at predetermined time intervals and irradiates light Lp of a predetermined wavelength for each illumination range (Ap1 to Ap4). That is, in this embodiment, the output of the optical pointer 22 is turned on and off to discretely irradiate each illumination range.

[0030] FIG. 8 is a diagram illustrating a control direction correspondence table provided in the underwater device 10. The underwater device 10 identifies the wavelength of the detected light Lp based on color information from image recognition or wavelength information of the light. The underwater device 10 then operates the drive unit 30 to move in a direction corresponding to the identified wavelength in accordance with the control direction correspondence table. Specifically, if the detected light Lp has wavelength 1, the drive unit 30 operates so that the underwater device 10 moves in a southeasterly direction (diagonally downward to the right in FIG. 6 ). By moving the underwater device 10 in this direction corresponding to the wavelength of the detected light Lp (the direction specified in the control direction correspondence table), the underwater device 10 can remain within the range Asig where underwater optical communication is possible.

[0031] (Example 2) A specific example will be described with reference to Figures 9 to 11. In the underwater equipment control system of this example, the arrangement of the optical signal transceiver 21 and the optical pointer 22 in the master unit 20 (e.g., the bottom of a ship) is the same as that of the underwater equipment control system of Example 1 (Figure 4). The underwater equipment control system of this example differs from the underwater equipment control system of Example 1 in that the optical pointer 22 constantly outputs light Lp, and switches the wavelength while moving the irradiation range of light Lp. Figure 9 is a diagram illustrating the irradiation range (Ap1 to Ap4, Ap12, Ap13, Ap24, Ap34) of light Lp from the optical pointer 22. There are irradiation areas (Ap12, Ap13, Ap24, Ap34) where the wavelengths of light Lp overlap. Note that in Figure 9, the trajectory of the center of light Lp is indicated by the symbol C. The optical pointer 22 irradiates light Lp clockwise to surround the underwater optical communication range Asig. The locus C may be counterclockwise or may be polygonal.

[0032] 10 is an image diagram illustrating the timing of irradiating light Lp in this embodiment. In order to improve the control accuracy of the underwater device 10, the optical pointer 22 outputs light Lp of two wavelengths in the range (time) where the irradiation range (Ap1 to Ap4) switches. In other words, the optical pointer 22 always outputs light.

[0033] FIG. 11 is a diagram illustrating a control direction correspondence table provided in the underwater device 10. The underwater device 10 identifies the wavelength of the detected light Lp based on color information from image recognition or wavelength information of the light. The underwater device 10 then operates the drive unit 30 to move in a direction corresponding to the identified wavelength according to the control direction correspondence table. Specifically, if the detected light Lp is light of wavelength 1 and wavelength 2, the drive unit 30 is operated so that the underwater device 10 travels south (downward in FIG. 9 ). By moving the underwater device 10 in a direction corresponding to the wavelength of the detected light Lp (the direction specified in the control direction correspondence table) in this way, the underwater device 10 can remain within the range Asig where underwater optical communication is possible.

[0034] 12 is a configuration diagram illustrating an underwater device 10 according to Examples 1 and 2. The underwater device 10 is movable underwater and performs underwater optical communication with a parent device 20, and includes: a detection unit 11 that detects light Lp of an optical pointer 22 irradiated from the parent device 20 so as to surround a range Asig in which underwater optical communication is possible; a control direction correspondence table 12 in which the direction of movement relative to the wavelength of the light Lp is set; a determination unit 13 that identifies the wavelength of the light Lp detected by the detection unit 11; and a control unit 14 that moves the underwater device 10 in accordance with the control direction correspondence table 12, based on the wavelength of the light Lp identified by the determination unit 13.

[0035] The underwater device 10 also includes components for underwater optical communication with the parent device 20 (an optical signal receiving unit 16, an optical signal transmitting unit 17, an optical signal processing unit 18, and a transmission information acquiring unit 19). The transmission information acquiring unit 19 acquires information about the environment of the underwater device 10 (e.g., temperature, water pressure, distance to obstacles, etc.). The optical signal processing unit 18 transmits the information about the environment as an optical signal from the optical signal transmitting unit 17 to the parent device 20. The optical signal processing unit 18 also analyzes the optical signal (instructions from the parent device 20) received by the optical signal receiving unit 16 from the parent device 20 and notifies the attitude control unit 14 to operate the underwater device 10 according to the instructions. The instructions from the parent device 20 include, for example, movement instructions (ascending, descending, horizontal movement, turning, etc.). The attitude control unit 14 controls the drive unit 30 to operate in accordance with the instructions from the parent device 20. The optical signal transmitting unit 17 and the optical signal receiving unit 16 may be integrated into a single unit.

[0036] For example, the detection unit 11 is a camera, and the determination unit 13 identifies the wavelength of the light Lp based on color information obtained from an image captured by the camera. The image processing unit 15 extracts color information from the image captured by the detection unit 11, which is a camera. The determination unit 13 identifies the wavelength of the light Lp currently irradiated onto the underwater device 10 based on the color information. The determination unit 13 also determines whether there is any overlap in wavelengths. The attitude control unit 14 compares the light pointer notified by the determination unit 13 with the control direction correspondence table 12 and determines the direction in which to move. The attitude control unit 14 then controls the drive unit 30 to move the underwater device 10 in that direction.

[0037] (Configuration Example 2 of Underwater Device) Because signals from the parent device 20 to control the underwater device 10 can have a low bit rate, acoustic signals, which have excellent underwater propagation characteristics, may be used as described in FIG. 1 . In this configuration example, the configuration of the underwater device 10 that can be controlled by acoustic signals is described. FIG. 13 is a configuration diagram illustrating the underwater device 10 of this configuration example. The underwater device 10 of this configuration example differs from the underwater device 10 of Configuration Example 1 in that it is equipped with an acoustic signal receiving unit 16a and an optical transmission / acoustic reception signal processing unit 18a instead of the optical signal receiving unit 16 and the optical signal processing unit 18. Other operations are the same as those of the underwater device 10 of Configuration Example 1.

[0038] 14 is a configuration diagram illustrating the underwater device 10 of this configuration example. In this configuration example, the detection unit 11 detects light Lp separated from light received by the light receiving unit 16 for underwater optical communication, and the determination unit 13 identifies the wavelength of the light Lp detected by the detection unit 11.

[0039] Specifically, the underwater device 10 includes a separation unit 15a that separates the light for underwater optical communication from the light Lp of the optical pointer 22. The separation unit 15a uses a wavelength filter to separate the light for underwater optical communication from the light of the optical pointer 22, taking advantage of the difference in wavelength. The light for underwater optical communication separated by the separation unit 15a is incident on the optical signal receiving unit 16, and the light Lp of the optical pointer 22 is incident on the detection unit 11. The operation beyond the optical signal receiving unit 16 and the detection unit 11 is the same as in configuration example 1.

[0040] (Configuration Example 4 of Underwater Device) Because signals from the parent device 20 to control the underwater device 10 can have a low bit rate, acoustic signals with excellent underwater propagation characteristics may be used, as described in FIG. 1 . In this configuration example, the configuration of an underwater device 10 that can be controlled by acoustic signals is described. FIG. 15 is a configuration diagram illustrating the underwater device 10 of this configuration example. The underwater device 10 of this configuration example differs from the underwater device 10 of Configuration Example 2 in that the detection unit 11 directly detects the light of the optical pointer 22 from the parent device 20, and the determination unit 13 identifies the optical pointer 22 from the wavelength of the light detected by the detection unit 11. The operation from the determination unit 13 and the acoustic signal receiving unit 16a onwards is the same as in Configuration Example 2.

[0041] In this embodiment, the number of wavelengths of the light Lp is four, but the number of wavelengths of the light Lp is not limited to four.

[0042] (Effects) The underwater device control system according to the present invention can autonomously control the underwater device 10 to stay within a desired range (a range where stable underwater optical communication is possible) by operating (such as changing the position of the irradiation target) the optical pointer from the master unit 20. Furthermore, since the underwater device control system according to the present invention uses only one optical pointer, it is possible to more economically control the position of the underwater device.

[0043] 10: Underwater device 11: Detection unit 12: Control direction correspondence table 13: Determination unit 14: Attitude control unit 15: Image processing unit 15a: Light separation unit 16: Optical signal receiving unit 16a: Acoustic signal receiving unit 17: Optical signal transmitting unit 18: Optical signal processing unit 18a: Optical transmission / acoustic reception signal processing unit 19: Transmission information acquisition unit 20: Parent unit 21: Optical signal transceiver 22: Optical pointer 30: Drive unit

Claims

1. A parent unit that performs underwater optical communication with underwater equipment that is movable underwater, comprising a transceiver for the underwater optical communication and a single optical pointer, the optical pointer sequentially irradiates light of different wavelengths so as to surround a range in which the underwater optical communication is possible, the wavelength of the light being determined by its position relative to the range.

2. The master unit according to claim 1, characterized in that the optical pointer provides a switching time during which the light is not emitted when the wavelength is changed.

3. The master unit according to claim 1, characterized in that the optical pointer provides an overlap time during which the wavelengths before and after the change overlap when the wavelength is changed.

4. An underwater equipment control system comprising: a parent unit having a transceiver for underwater optical communication and a single optical pointer; and underwater equipment movable underwater and performing underwater optical communication with the parent unit, wherein the parent unit sequentially irradiates the light of the optical pointer while changing the wavelength so as to surround a range in which the underwater optical communication is possible, and the wavelength of the light of the optical pointer is determined by its position relative to the range, and the underwater equipment comprises: a detection unit that detects the light of the optical pointer; a control direction correspondence table in which the direction to move for the wavelength of light is set; a judgment unit that identifies the wavelength of light detected by the detection unit; and a control unit that moves the underwater equipment in accordance with the control direction correspondence table based on the wavelength of light identified by the judgment unit.

5. An underwater equipment control method for controlling the position of underwater equipment that is movable underwater and performs underwater optical communication with a parent unit having a transceiver for underwater optical communication and a single optical pointer, wherein the parent unit: sequentially irradiates the light of the optical pointer while changing the wavelength so as to surround a range in which underwater optical communication is possible, and the wavelength of the light of the optical pointer is determined by its position relative to the range; and the underwater equipment has a control direction correspondence table in which the direction in which the underwater equipment should move relative to the wavelength of the light of the optical pointer is set; the underwater equipment control method comprises the steps of: detecting the light of the optical pointer, identifying the wavelength of the detected light, and moving the underwater equipment in accordance with the control direction correspondence table based on the identified wavelength.

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