Remotely operated underwater vehicle and cooling method for a projection device mounted on the remotely operated underwater vehicle

Abstract

To provide a remote operation type underwater movement body capable of projecting a stable video under water.SOLUTION: A remote operation type underwater movement body includes a frame body 10 with a waterproof function which incorporates a projection device 20 for displaying a projection video on an external projection surface, a projection video correction part for correcting the projection video, a light source 30 using the projection device 20 and a flowing water tube 50 for cooling the light source 30 and through which the flowing water tube 50 penetrates. The projection video correction part corrects the projection video, so that the frame body 10 has predetermined size and shape on the projection surface according to a distance from the projection device 20 to the projection surface and an angle formed by the projection surface and the optical axis of light with which the projection surface is irradiated, when the projection video is enlarged or reduced, or deformed by the movement in the tube axial direction of the flowing water tube 50.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to a remotely operated underwater vehicle and a cooling method for a projection device mounted on the remotely operated underwater vehicle. [Background technology]

[0002] In recent years, underwater projectors that project images underwater onto a wall surface or the like have been proposed (see, for example, Patent Document 1). This underwater projector has a projector body disposed in a waterproof housing, a heat exchanger disposed along the outer surface of the projector body and having a cooling water channel formed therein, and a water pump that circulates water between the cooling water channel and the outside of the underwater projector. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2008-216412 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, since the underwater projector described above includes a heat exchanger and a water pump, the entire device may become large and heavy. Therefore, an object of an embodiment of the present disclosure is to provide a remote-operated underwater vehicle capable of remotely controlling accurate projection by a projection device while moving underwater, and a cooling method for a projection device mounted on the remote-operated underwater vehicle. [Means for solving the problem]

[0005] A remote-controlled underwater vehicle according to one embodiment of the present invention has a projection device that displays a projected image on an external projection surface, a projection image correction unit that corrects the projected image, a light source used in the projection device, a heat dissipation mechanism that dissipates heat from the light source, and a running water tube for cooling the light source, and has a frame body with a waterproof function through which the running water tube passes, and the projection image correction unit is configured to correct the projected image so that it has a predetermined size and shape on the projection surface depending on the distance from the projection device to the projection surface and the angle between the projection surface and the optical axis of the light irradiated to the projection surface when the projected image is enlarged, reduced, or deformed due to movement of the frame body in the tube axis direction of the running water tube.

[0006] In addition, a remote-controlled underwater vehicle according to one embodiment of the present invention is configured to include a projection device that displays a projected image on an external projection surface, a frame body that incorporates a light source used in the projection device, a heat dissipation mechanism that dissipates heat from the light source, and a running water pipe for cooling the light source, and has a waterproofing function through which the running water pipe passes, a photographing camera that captures the projected image displayed on the projection surface as a photographed image, a temperature sensor that measures the temperature at a predetermined location of the projection device, a distance sensor that measures the distance from the projection device to the projection surface, a movement control unit that generates thrust alternately along the front and rear directions of the tube axis of the running water pipe when the temperature measured by the temperature sensor exceeds a predetermined threshold value, a focus control unit that controls the projection device so that the projected image is focused on the projection surface based on the distance measured by the distance sensor, and a projection image correction unit that corrects the projected image so that the size and aspect ratio of the photographed image captured by the photographing camera are desired values.

[0007] In addition, a cooling method for a projection device mounted on a remote-operated underwater vehicle according to one embodiment of the present invention is a cooling method for a projection device mounted on a remote-operated underwater vehicle having a waterproof function, the cooling method comprising: a projection device that displays a projected image on an external projection surface; a projection image correction unit that corrects the projected image; a light source used in the projection device; a heat dissipation mechanism that dissipates heat from the light source; and a running water pipe for cooling the light source, the running water pipe being disposed so as to penetrate the frame body; a photographing camera that photographs the projected image displayed on the projection surface as a photographed image; a temperature sensor that measures the temperature of the light source; and a distance sensor that measures the distance to the projection surface, the cooling method comprising the steps of: a movement control unit that moves the remote-operated underwater vehicle along the tube axial direction of the running water pipe when a temperature measured by the temperature sensor exceeds a predetermined threshold value; a focus control unit that controls the projection device so that the projected image is focused on the projection surface based on the distance measured by the distance sensor; and the projection image correction unit that corrects the projected image so that the size and aspect ratio of the photographed image photographed by the photographing camera become desired values. Effect of the Invention

[0008] According to one embodiment of the present invention, a remotely operated underwater vehicle and a cooling method for a projection device mounted on the remotely operated underwater vehicle can project an image at a desired position underwater while cooling the projection device. [Brief description of the drawings]

[0009] [Figure 1] FIG. 2 is a perspective view showing a frame body of an underwater drone (remotely controlled underwater vehicle) according to an embodiment of the present disclosure. [Diagram 2] FIG. 2 is a cross-sectional view of a light source and a heat dissipation mechanism that pass through the water flow pipe of the underwater drone of FIG. [Diagram 3] FIG. 2 is a block diagram showing the functional configuration of the underwater drone in FIG. 1. [Figure 4] FIG. 2 is an explanatory diagram illustrating how the underwater drone in FIG. 1 projects an image onto the wall inside the aquarium. [Diagram 5]FIG. 5 is an explanatory diagram illustrating how the image projected in FIG. 4 is observed outside the aquarium. [Figure 6] FIG. 13 is an explanatory diagram illustrating the projected image when the underwater drone is horizontal. [Figure 7] FIG. 13 is an explanatory diagram illustrating a projected image when the underwater drone is tilted forward. [Figure 8] FIG. 1 is an explanatory diagram illustrating the relationship between the attitude of the underwater drone, the projected image before projection, the projected image after projection, and the image captured by the camera. [Figure 9A] FIG. 1 is an explanatory diagram illustrating a captured image including a projection image without distortion. [Figure 9B] FIG. 1 is an explanatory diagram illustrating a captured image including a distorted projected image. [Figure 9C] FIG. 13 is an explanatory diagram for explaining a maximum rectangular area. [Figure 9D] FIG. 11 is an explanatory diagram for explaining zooming of a projected image. [Figure 9E] FIG. 11 is an explanatory diagram for explaining correction of a projected image. [Figure 10] FIG. 13 is an explanatory diagram of a corrected projected image when the underwater drone is tilted forward. [Figure 11] 13 is a flowchart showing the operation of the underwater drone cooling the projection device. [Figure 12] 13 is a flowchart showing the operation of an underwater drone to correct a projected image. [Figure 13] FIG. 11 is a perspective view showing a frame body of an underwater drone according to another embodiment of the present disclosure. [Figure 14A] FIG. 13 is a top view of an underwater screw of an underwater drone according to another embodiment of the present disclosure. [Figure 14B] FIG. 13 is a side view of an underwater screw of an underwater drone according to another embodiment of the present disclosure. [Figure 14C] FIG. 13 is a front view of an underwater screw of an underwater drone according to another embodiment of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, the embodiments of the invention will be described with reference to the drawings as appropriate. However, the embodiments described below are intended to embody the technical ideas of the present invention, and unless otherwise specified, the present invention is not limited to the following. Furthermore, the sizes and positional relationships of the components shown in the drawings may be exaggerated for clarity of explanation.

[0011] In the following description, the projection direction of the projection device 20 in FIG. 1 is the forward direction of the underwater drone 1, and the opposite direction to this forward direction is the backward direction of the underwater drone 1. FIG. 1 is a perspective view of a frame body of an underwater drone (remotely controlled underwater moving body) according to an embodiment of the present disclosure. FIG. 2 is a cross-sectional view of a light source and a heat dissipation mechanism through which a running water pipe of the underwater drone in FIG. 1 is inserted. FIG. 3 is a block diagram showing the functional configuration of the underwater drone in FIG. 1. FIG. 4 is an explanatory diagram explaining a state in which an image is projected on a wall surface in an aquarium by the underwater drone in FIG. 1. FIG. 5 is an explanatory diagram explaining a state in which the image projected in FIG. 4 is observed outside the aquarium.

[0012] <Structure of underwater drone> As shown in Figures 1 to 3, an underwater drone (remotely controlled underwater vehicle) 1 has a projection device 20 that displays a projected image on an external projection surface, a projection image correction unit 150 that corrects the projected image, a light source 30 used in the projection device 20, a heat dissipation mechanism 40 that dissipates heat from the light source 30, and a running water tube 50 for cooling the light source 30.The projection image correction unit 150 has a waterproof frame body 10 through which the running water tube 50 passes, and corrects the projected image so that it has a predetermined size and shape on the projection surface depending on the distance from the projection device 20 to the projection surface and the angle between the projection surface and the optical axis of the light irradiated to the projection surface when the projected image is enlarged, reduced, or deformed due to the frame body 10 moving in the tube axis direction of the running water tube 50.

[0013] In other words, the underwater drone 1 is a drone that can be remotely controlled to move underwater where an image is projected by the projection device 20. When the light source 30 used in the projection device 20 is heated to a predetermined temperature, the underwater drone 1 moves (reciprocates), for example, in a forward and backward direction to create a water flow in the water flow pipe 50. Furthermore, the underwater drone 1 corrects the projected image during movement so that the projected image is not distorted into a trapezoid. For example, as shown in FIG. 4, the underwater drone 1 moves underwater in an aquarium 200 and projects a projection image P onto a wall surface W of the aquarium 200, so that an external observer H can view the projection image P. As shown in FIG. 5, a projected image P is projected onto a wall surface W of the aquarium 200, as viewed by an external observer H shown in FIG. 4. In this embodiment, the projected image P shows an example of an image of fish swimming. In this manner, the underwater drone 1 can display any image within the aquarium 200. This allows the underwater drone 1 to present to the observer H an image as if fish were swimming within the aquarium 200.

[0014] Here, the underwater drone 1 mainly comprises a frame body 10 having a projection device 20, a light source 30, a heat dissipation mechanism 40, a distance sensor 60, a temperature sensor 70, a photographing camera 80, and a control unit 100 therein, and a screw 90. The projection device 20 may include a spatial light modulator 21 that modulates the light sent from the light source 30 to form an image, and a projection lens 22 that sends the light from the spatial light modulator 21 to a projection surface. The frame body 10 may have an underwater screw 90 and a support arm 91 that supports the underwater screw 90 on the outer periphery, and may include the projection device 20, the light source 30, and a heat dissipation mechanism 40 inside. The water flow pipe 50 is formed so as to penetrate the frame body 10 in the projection direction of the projection device 20 and cool the light source 30. The heat dissipation mechanism 40 may include a rod lens 43 that sends light from the light source 30 to the spatial light modulator 21. This allows the underwater drone 1 to project an image at a desired position underwater and cool the projection device 20.

[0015] The frame body 10 is a component that forms the skeleton of the underwater drone 1, and has waterproof properties due to materials such as carbon, nylon, metals such as aluminum, and resins such as polyurethane and Delrin. A water flow pipe 50 penetrates the frame body 10 so that the direction of the pipe axis is the same as the traveling direction (forward or backward direction) of the underwater drone 1. A distance sensor 60 and a photographing camera 80 are arranged on the frame body 10 facing the forward direction of the underwater drone 1. In Fig. 1, a ceiling board (top board) 13 is illustrated by a two-dot chain line so that the inside of the frame body 10 can be seen. The frame body 10 is provided with a screw (underwater screw) 90 and a support arm 91 that supports the screw on its outer periphery.

[0016] The screw 90 is provided with first drive screws 90R1, 90L1 that move the underwater drone 1 forward or backward or rotate left and right, and second drive screws 90R2, 90L2 that move the underwater drone 1 up and down, on the left and right sides of the frame body 10. The screw 90 is driven by a drive signal from the control unit 100 inside the frame body 10. The screw 90 generates thrust in the underwater drone 1 according to the rotation direction instructed by the drive signal. The direction of thrust of the screw 90 is reversed between forward and reverse rotation.

[0017] The first drive screws 90R1, 90L1 generate thrust in a forward direction, a backward direction, or a left / right rotation direction for the underwater drone 1. Here, the first drive screws 90R1, 90L1 are provided in a pair on the left and right sides of the frame body 10. The first drive screws 90R1, 90L1 both rotate in the forward direction to generate a thrust in the forward direction. As a result, the underwater drone 1 moves in the forward direction. The first drive screws 90R1, 90L1 both rotate in the reverse direction to generate a thrust in the backward direction. As a result, the underwater drone 1 moves in the backward direction. Furthermore, the first drive screws 90R1, 90L1 generate thrust in the left and right rotational directions by rotating in different directions. For example, when the first drive screw 90R1 rotates forward and the first drive screw 90L1 rotates backward, a thrust in the left rotational direction is generated. This causes the underwater drone 1 to rotate in the left direction. Also, when the first drive screw 90R1 rotates backward and the first drive screw 90L1 rotates forward, a thrust in the right rotational direction is generated. This causes the underwater drone 1 to rotate in the right direction.

[0018] The second drive screws 90R2, 90L2 generate vertical thrust for the underwater drone 1. Here, two pairs of the second drive screws 90R2, 90L2 are provided on the left and right sides of the frame body 10. The second drive screws 90R2, 90L2 both rotate in the forward direction to generate an upward thrust. This causes the underwater drone 1 to move upward. Additionally, the second drive screws 90R2, 90L2 both rotate in the reverse direction to generate a downward thrust. This causes the underwater drone 1 to move downward. Additionally, the second drive screws 90R2, 90L2 rotate in different directions on the left and right, which can generate left and right tilt or correct the tilt. In order to reduce the influence of water flow, it is preferable that the support arms 91 for the first drive screws 90R1, 90L1 and the second drive screws 90R2, 90L2 have different lengths.

[0019] The projection device 20 projects an image. The projection device 20 includes a spatial light modulator 21 that modulates light sent from a light source 30 to form an image, a projection lens 22 that projects the light from the spatial light modulator 21 onto a projection surface, and a lens adjustment mechanism 23. The spatial light modulator 21 modulates the light sent from the light source 30 to form an image, and is, for example, a digital micromirror device (DMD). This DMD has tiny movable reflecting mirrors aligned in two dimensions, and drives the angles of the reflecting mirrors based on control signals from the control unit 100 to match the image. The spatial light modulator 21 can be configured with either a reflective or transmissive liquid crystal element. When a reflective liquid crystal element is used as the spatial light modulator 21, light sent from the light source 30 is irradiated onto the spatial light modulator 21 via a beam splitter, and the image light of the spatial light modulator 21 is output. When a transmissive liquid crystal element is used as the spatial light modulator 21, light is irradiated onto the optical path of the light source 30 from the rear side of the spatial light modulator 21, and the image light is output from the spatial light modulator 21.

[0020] The projection lens 22 transmits (projects) the light from the spatial light modulator 21 onto a projection surface, and is, for example, a single lens or a group of lenses. The projection lens 22 is installed so that a part of the objective lens surface is exposed from the frame body 10. The lens adjustment mechanism 23 adjusts the focus by moving the position of the projection lens 22 along the optical axis, and also adjusts the zoom of the image.

[0021] The light source 30 emits light for projecting an image by the projection device 20. For example, the light source 30 is a laser light source module in which a semiconductor laser 31 that emits light to the projection device 20 is packaged. The light source 30 may be an LED light source module that uses an LED.

[0022] The heat dissipation mechanism 40 is installed in the left-right direction so as to be perpendicular to the water pipe 50 . Moreover, one end of the heat dissipation mechanism 40 is bonded to the light source 30 so as to be able to dissipate heat transferred from the light source 30. For example, the heat dissipation mechanism 40 includes two heat pipes 41 and a heat sink .

[0023] The heat pipe 41 is formed into a U-shape by folding back the center of a rod-shaped member formed to a predetermined length in the left-right direction. The straight portion of the U-shape of the heat pipe 41 contacts the heat sink 42, and the center portion contacts the rear surface side of the light source 30, and transfers heat from the light source 30 to the heat sink 42.

[0024] The heat sink 42 is a member that dissipates heat from the light source 30 transmitted from the heat pipes 41, and is formed in two stages, upper and lower. The heat sink 42 has the heat pipes 41 disposed in both the upper stage recess and the lower stage recess. For example, the heat sink 42 is made of thin plates arranged at regular intervals to increase the surface area and enable efficient heat dissipation. The heat pipes 41 and the heat sink 42 are preferably made of a material with high thermal conductivity, such as aluminum or copper.

[0025] Furthermore, in the heat dissipation mechanism 40, a rod lens 43 is provided to allow the light from the light source 30 (semiconductor laser 31) to reach the spatial light modulator 21. Rod lens 43 is a glass rod lens that converts the light having a non-uniform luminance distribution from light source 30 into illumination having a uniform luminance distribution.

[0026] The water flow pipe 50 is formed penetrating the frame body 10 from front to rear so as to generate a water flow in the pipe axial direction as the underwater drone 1 moves forward or backward. Furthermore, the water pipe 50 is disposed so as to be in contact with the light emitting portion of the light source 30 in order to cool the light source 30 by the flowing water in the pipe. For example, as shown in Fig. 2, the water pipe 50 can be formed so as to penetrate the portion where the light source 30 and the heat dissipation mechanism 40 are in contact. The water pipe 50 is preferably made of a material with high thermal conductivity, such as aluminum or copper, in order to cool the heat by the flowing water.

[0027] When the underwater drone 1 moves forward, a water flow α from the front to the rear occurs in the water flow pipe 50, dissipating heat from the light source 30. When the underwater drone 1 moves backward, a water flow (opposite to α) from the rear to the front occurs in the water flow pipe 50, dissipating heat from the light source 30. In order to efficiently cool the light source 30, the water pipe 50 is formed so as to penetrate the laser light source module in which the semiconductor laser 31 is packaged. The water flow pipe 50 is configured to penetrate the frame body 10, and has the function of cooling the light source 30 and also cooling the heat generated by the heat dissipation mechanism 40.

[0028] The distance sensor 60 measures the distance from the underwater drone 1 to a projection surface (for example, a wall surface) and outputs the measured distance to the control unit 100. For example, the distance sensor 60 measures the distance by a LiDAR (Light Detection And Ranging) method. Here, the distance sensor 60 includes a spectroscopic means 61 , an optical path changing means 62 , a half mirror 63 and a light detection unit 64 .

[0029] The spectroscopic means 61 separates blue light (blue laser light) contained in the light emitted by the light source 30. For example, a dichroic beam splitter can be used as the spectroscopic means 61. The spectroscopic means 61 is disposed on the optical path of the light emitted by the light source 30, and splits the blue light. The spectroscopic means 61 irradiates the split blue light to the optical path changing means 62.

[0030] The optical path changing means 62 changes the optical path of the blue light split by the spectroscopic means 61 to the forward direction of the underwater drone 1. The optical path changing means 62 can be composed of a general mirror, etc. The optical path changing means 62 irradiates the blue light onto a half mirror 63 arranged in the forward direction.

[0031] The half mirror 63 reflects light incident on one surface and transmits light incident on the other surface. The half mirror 63 irradiates the blue light irradiated from the optical path changing means 62 in the forward direction of the underwater drone 1 through an opening window 65. The half mirror 63 also receives the reflected light of the blue light irradiated in the forward direction through the opening window 65 and reflects it in the direction of the light detection unit 64. The opening window 65 is made of a transparent material such as glass.

[0032] The light detection unit 64 detects light. For example, the light detection unit 64 can be configured to include a photodiode. The light detection unit 64 measures the distance based on the time difference between the light emitted from the light source 30 and the light detected. The light detection unit 64 periodically measures the distance by making the light source 30 emit light. The light detection unit 64 outputs the measured distance to the control unit 100.

[0033] The temperature sensor 70 measures the temperature of the light source 30 and outputs the measured temperature to the control unit 100. The temperature sensor 70 is disposed at a predetermined temperature detection point of the light source 30 (laser light source module). For example, the temperature sensor 70 may be a thermistor, a thermocouple, or a platinum resistance temperature detector.

[0034] The photographing camera 80 photographs the projected image displayed on the projection surface by the projection device 20 as a photographed image, and outputs the photographed image to the control unit 100. The photographing camera 80 has a photographing angle of view that is sufficiently wider than the projection angle of view of the projection device 20 so that the entire range of the projected image of the projection device 20 fits into the photographed image. For example, the photographing camera 80 is a small CCD (Charged Coupled Devices) camera.

[0035] (Control Unit Configuration) The configuration of the control unit 100 will be described in detail with reference to FIG. As shown in FIG. 3, the control unit 100 includes a memory 110, an operation signal receiving unit 120, a movement control unit 130, a focus control unit 140, and a projected image correction unit 150.

[0036] The memory 110 is a storage device such as a RAM (Random Access Memory) that stores various information required by the underwater drone 1. For example, the memory 110 stores a projection image that the underwater drone 1 projects to the outside. This memory 110 is referenced by the movement control unit 130, the focus control unit 140, and the projection image correction unit 150, which will be described later.

[0037] The operation signal receiving unit 120 receives an operation signal for moving the underwater drone 1 from a transmitter (not shown) via wireless communication, and outputs the received operation signal to the movement control unit 130. For example, the movement operations of the underwater drone 1 include a throttle for raising or lowering the underwater drone 1, an elevator for moving the underwater drone 1 forward or backward, an aileron for moving the underwater drone 1 left and right, and a rudder for rotating the underwater drone 1 clockwise or counterclockwise. Furthermore, the operation signal receiving unit 120 receives an operation signal for operating the projection device 20 from the transmitter via wireless communication, and outputs the received operation signal to the focus control unit 140. For example, the operation of the projection device 20 includes starting and ending shooting.

[0038] The movement control unit 130 controls the movement of the underwater drone 1 based on the operation signal input from the operation signal receiving unit 120. The underwater drone 1 changes its attitude depending on the difference in the number of rotations and the direction of rotation of each screw 90, and moves forward and backward, up and down, and left and right. Therefore, the movement control unit 130 controls the number of rotations and the direction of rotation of each screw 90 so that the underwater drone 1 moves in response to the operation signal. The movement control unit 130 may also stabilize the attitude of the underwater drone 1 using the attitude information of the gyro sensor 170. In this way, the movement control unit 130 has the same function as a flight controller of a general drone.

[0039] The movement control unit 130 receives the temperature of the light source 30 from the temperature sensor 70 and judges the input temperature against a threshold value. The movement control unit 130 moves the underwater drone 1 back and forth along the direction of the tube axis of the flowing water pipe 50 while the temperature measured by the temperature sensor 70 exceeds the threshold value. The movement control unit 130 can set this threshold value arbitrarily, for example, to a value equal to or lower than the heat resistance characteristic of the light source 30. The movement control unit 130 can also set the distance for the underwater drone 1 to travel back and forth arbitrarily. In this way, the movement control unit 130 can move the underwater drone 1 back and forth to suppress overheating of the light source 30. The temperature input to the movement control unit 130 may be any temperature that is correlated with the temperature of the light source 30, and does not have to be the temperature of the light source 30 itself. In addition, when an operation signal is input from the operation signal receiving unit 120 while the underwater drone 1 is moving back and forth, the movement control unit 130 may give priority to the operation signal.

[0040] Furthermore, when the underwater drone 1 moves autonomously, the operation signal receiving unit 120 does not need to receive an operation signal. In this case, route information indicating the movement route of the underwater drone 1 is stored in advance in the memory 110. Then, the movement control unit 130 refers to the route information in the memory 110 and the position information of the GPS 160, and moves the underwater drone 1 along the movement route.

[0041] The focus control unit 140 receives a distance from the distance sensor 60 and controls the projection device 20 based on the input distance so that the projected image is focused on the projection surface. That is, the focus control unit 140 controls the lens adjustment mechanism 23 so that the projection device 20 focuses on the projection surface. When the focus control unit 140 receives an operation signal from the operation signal receiving unit 120, the focus control unit 140 controls the projection device 20 in response to the signal to focus the projected image.

[0042] The projection image correction unit 150 corrects the projection image so that the size and aspect ratio of the image captured by the capturing camera 80 become the desired values. That is, when the projection image is enlarged, reduced, or deformed due to the movement of the underwater drone 1, the projection image correction unit 150 corrects the projection image so that it has a predetermined size and shape on the projection surface according to the distance from the underwater drone 1 to the projection surface and the angle with respect to the projection surface. Then, the projection image correction unit 150 outputs the corrected projection image to the projection device 20. In addition, the projected image correction unit 150 determines whether or not the underwater drone 1 is tilted from the attitude information of the gyro sensor 170, and if the underwater drone 1 is not tilted, it is not necessary to correct the projected image.

[0043] <Focus adjustment, correction of projected image> With reference to FIG. 6 to FIG. 10, the focus adjustment and the correction of the projection image will be described in detail. FIG. 6 is an explanatory diagram for explaining the projection image when the underwater drone is horizontal. FIG. 7 is an explanatory diagram for explaining the projection image when the underwater drone is tilted forward. FIG. 8 is an explanatory diagram for explaining the relationship between the attitude of the underwater drone, the projection image before projection, the projection image after projection, and the photographed image of the photographing camera. FIG. 9A is an explanatory diagram for explaining the photographed image including the projection image without distortion. FIG. 9B is an explanatory diagram for explaining the photographed image including the projection image with distortion. FIG. 9C is an explanatory diagram for explaining the maximum rectangular area. FIG. 9D is an explanatory diagram for explaining the zoom of the projection image. FIG. 9E is an explanatory diagram for explaining the correction of the projection image. FIG. 10 is an explanatory diagram for explaining the projection image after correction when the underwater drone is tilted forward. In FIG. 6, the projection range of the projection image P is illustrated by a dashed line, and the photographed image of the photographing camera 80 is represented by the symbol C.

[0044] The underwater drone 1 maintains a horizontal posture when stationary. The distance sensor 60 measures the distance L1 from the underwater drone 1 to the wall surface W, and the focus control unit 140 adjusts the focus of the projection device 20 to the wall surface W. Here, since the underwater drone 1 is not tilted, the projection device 20 projects a rectangular projection image P0 without distortion onto the wall surface W. The captured image C includes the entire range of the projected image P projected onto the wall surface W.

[0045] As shown in FIG. 7, the underwater drone 1 may be in a forward-tilting posture when moving forward. As in the stationary state in FIG. 6, the distance sensor 60 measures the distance L1 from the underwater drone 1 to the wall surface W. At this time, the focus control unit 140 may correct the distance L1 measured by the distance sensor 60 using a trigonometric function according to the tilt angle θ of the underwater drone 1 measured by the gyro sensor 170. In FIG. 7, the corrected distance is illustrated by the symbol L2. In addition, since the underwater drone 1 is inclined forward, the projection device 20 projects a trapezoidally distorted projection image P1 onto the wall surface W.

[0046] The upper part of Fig. 8 illustrates a projection image P before projection, a projection image P0 after projection, and an image C captured by the photographing camera 80 when the underwater drone 1 is horizontal. The lower part of Fig. 8 illustrates a projection image P before projection, a projection image P1 after projection, and an image C captured by the photographing camera 80 when the underwater drone 1 is tilted forward.

[0047] As shown in FIG. 8, the projection image P before being projected onto the wall surface W is not distorted regardless of the attitude of the underwater drone 1. When the underwater drone 1 is horizontal, the projection image P0 actually projected onto the wall surface W is not distorted, but when the underwater drone 1 is tilted forward, the projection image P1 projected onto the wall surface W is distorted into a trapezoidal shape. Therefore, the shooting camera 80 of the underwater drone 1 captures the projection image P0 without distortion when the underwater drone 1 is horizontal, but captures the projection image P1 with distortion when the underwater drone 1 is tilted forward. Therefore, as described below, the underwater drone 1 corrects the distortion of the projection image P1 using the shooting image C.

[0048] Fig. 9A shows a captured image C including a undistorted projection image P0 when the underwater drone 1 is horizontal. Fig. 9B shows a captured image C including a distorted projection image P1 when the underwater drone 1 is tilted forward. Comparing the undistorted projection image P0 and the distorted projection image P1, the projection image P1 is displayed below the projection image P0, and has a smaller area.

[0049] First, as shown in FIG. 9C, the projection image correction unit 150 obtains the maximum rectangular area M that overlaps the rectangular projection image P0 captured when the underwater drone 1 is horizontal, from among the trapezoidal projection image P1 captured when the underwater drone 1 is moving forward. The maximum rectangular area M is the maximum rectangular area inscribed in the area where the projection images P0 and P1 overlap. For example, the projection image correction unit 150 detects a rectangular area representing the projection image P0 from the image C captured when the underwater drone 1 is horizontal, and detects a trapezoidal area representing the projection image P1 from the image C captured when the underwater drone 1 is moving forward. Then, the projection image correction unit 150 obtains the maximum rectangular area M inscribed in the area where the detected rectangular area and trapezoidal area overlap. Next, projected image correcting section 150 obtains, from projected image P0, a surplus area D other than maximum rectangular area M. Note that in Fig. 9C, surplus area D is illustrated by hatching.

[0050] Next, the projection image correction unit 150 corrects the projection image P so that the excess area D is removed from the projection image P and the projection image P after the removal is zoomed according to the size of the rectangular projection image P0. For example, the projection image correction unit 150 trims the excess area D from the projection image P in the memory 110. Then, as shown in FIG. 9D, the projection image correction unit 150 generates a projection image P2 zoomed from the trimmed projection image P to match the size and aspect ratio (for example, 16:9, 4:3) of the projection image P0. At this time, the projection image correction unit 150 may perform either electronic zoom for interpolating and enlarging the projection image P or optical zoom using the lens adjustment mechanism 23. Furthermore, as shown in FIG. 9E, the projection image correction unit 150 corrects (projectively transforms) the projection image P2 to an inverted trapezoidal shape in consideration of the fact that the projection image P1 is distorted into a trapezoidal shape when the underwater drone 1 moves forward. In FIG. 9, the projection position of the projected image P may be shifted slightly up or down.

[0051] As described above, the underwater drone 1 corrects the projected image P while moving, as shown in FIG. 10, so that it can display a distortion-free rectangular projected image P0 even when moving forward from the reference position. In addition, in Figures 7 to 10, the underwater drone 1 has been described as moving forward (tilting forward), but the image can also be corrected in a similar manner when the underwater drone 1 moves backward (tilting backward).

[0052] <Underwater drone operation: cooling of projection device> The operation of the underwater drone 1 to cool the projection device 20 will be described with reference to Fig. 11. Fig. 11 is a flowchart showing the operation of the underwater drone to cool the projection device. In step S1, the underwater drone 1 turns on the light source 30. In step S 2 , the temperature sensor 70 measures the temperature of the light source 30 . In step S3, the movement control unit 130 determines whether the temperature of the light source 30 measured in step S2 exceeds a threshold value.

[0053] If the temperature of the light source 30 exceeds the threshold value (Yes in step S3), the movement control unit 130 determines to move the underwater drone 1 forward or backward from a preset reference position (step S4). If the temperature of the light source 30 does not exceed the threshold value (No in step S3), the movement control unit 130 determines to cause the underwater drone 1 to wait at the reference position (step S5). In step S6, the movement control unit 130 outputs to the screw 90 a control signal according to the result of the determination in step S4 or step S5.

[0054] <Drone operation: Correction of projected images> The operation of the underwater drone 1 to correct the projected image will be described with reference to Fig. 12. Fig. 12 is a flowchart showing the operation of the underwater drone to correct the projected image. In step S10, the projection device 20 projects an image. In step S11, the distance sensor 60 measures the distance from the underwater drone 1 to the projection surface.

[0055] In step S12, focus control unit 140 controls the focus of projection device 20 based on the distance measured in step S11 so that the projected image is focused on the projection surface. In step S13, the photographing camera 80 photographs the image projected onto the projection surface. In step S14, projected image correction unit 150 corrects the projected image so that the size and aspect ratio of the image captured in step S13 have desired values.

[0056] As described above, when the light source 30 exceeds a predetermined temperature, the underwater drone 1 moves back and forth, thereby preventing overheating of the light source 30 and enabling stable image projection. At this time, even if the underwater drone 1 is tilted forward or backward, it corrects the trapezoidally distorted projection image, allowing the projection of an image that is easy for the observer to see.

[0057] (Modification) Although the embodiments of the present disclosure have been described above, the present disclosure is not limited to the above-described embodiments and can be appropriately modified and implemented. Here, the first drive screws 90R1, 90L1 are configured to be provided in pairs at the rear of the frame body of the underwater drone 1, but they may be provided in either the center or the front. In that case, it is preferable to position the first drive screws 90R1, 90L1 at a position offset from the rotation axis of the second drive screws 90R2, 90L2 so as not to interfere with the water flow of the second drive screws 90R2, 90L2. The second drive screws 90R2, 90L2 are configured to be provided in two pairs on the left and right sides of the frame body of the underwater drone 1, but three or more pairs may be provided.

[0058] Also, here, the underwater drone 1 is configured to have one water flow pipe 50 for cooling the light source 30 penetrating the frame body 10. However, the frame body 10 may be configured to have a water flow pipe 50 penetrating in the front-rear direction on either the left or right side based on the center in the left-right direction, and a second water flow pipe 50 penetrating in the front-rear direction on the other side. 13 shows an example in which two water flow pipes 50 (50R, 50L) penetrate the frame body 10. In this case, the water flow pipe 50L has the function of cooling the light source 30 by the water flow α in the tube axis direction accompanying the forward or backward movement of the underwater drone 1. On the other hand, it is preferable that the water flow pipe 50R penetrates the frame body 10 at a position that is approximately symmetrical to the water flow pipe 50L in the left-right direction of the frame body 10. These two water flow pipes 50R, 50L enable the underwater drone 1 to stabilize the left-right balance during movement.

[0059] In addition, here, the underwater drone 1 is configured such that the screw 90 is supported by the support arm 91 with the rotation axis fixed. However, the screw 90 of the underwater drone 1 may be configured such that the rotation axis is variable. For example, as shown in the top view of FIG. 14A, the side view of FIG. 14B, and the front view of FIG. 14C, the support arm 91 may be configured to include a rotation mechanism 91a that rotates the rotation axis of the screw 90 about an axis perpendicular to the rotation axis. As a result, the second drive screws 90R2, 90L2 can not only move the underwater drone 1 up and down, but also left and right, including diagonally. [Explanation of symbols]

[0060] 1. Underwater drones (remotely controlled underwater vehicles) 10 Frame body 20 Projection device 21 Spatial Light Modulator 22 Projection Lens 23 Lens adjustment mechanism 30 light source 31 Semiconductor laser 40 Heat dissipation mechanism 41 Heat Pipe 42 Heat sink 43 Rod Lens 50 Water pipe 60 Distance Sensor 61 Spectroscopic means 62 Optical path changing means 63 Half Mirror 64 Light detection unit 70 Temperature Sensor 80 Camera 90 Screw (underwater screw) 91 Support Arm 91a Rotation mechanism 100 Control section 110 Memory 120 Operation signal receiving unit 130 Movement control section 140 Focus control section 150 Projection image correction unit 160 GPS 170 Gyro sensor

Claims

1. a projection device for displaying a projected image on an external projection surface, a projection image correction unit for correcting the projected image, a light source for use in the projection device, a heat dissipation mechanism for dissipating heat from the light source, and a water flow pipe for cooling the light source, the water flow pipe passing through the water flow pipe, The projected image correction unit is a remote-controlled underwater vehicle that, when the frame body moves in the axial direction of the flowing water pipe, corrects the projected image so that it has a predetermined size and shape on the projection screen, depending on the distance from the projection device to the projection screen and the angle between the projection screen and the optical axis of the light irradiated to the projection screen.

2. a projection device for displaying a projected image on an external projection surface, a light source for use in the projection device, a heat dissipation mechanism for dissipating heat from the light source, and a water flow pipe for cooling the light source, the water flow pipe passing through the water flow pipe; and a waterproof frame body having the built-in light source and the heat dissipation mechanism for dissipating heat from the light source and a water flow pipe for cooling the light source. a photographing camera that photographs the projected image displayed on the projection screen as a photographed image; a temperature sensor for measuring a temperature at a predetermined location of the projection device; a distance sensor for measuring a distance from the projection device to the projection surface; a movement control unit that generates thrusts alternately along a front-rear direction of a pipe axis of the water pipe when the temperature measured by the temperature sensor exceeds a predetermined threshold value; a focus control unit that controls the projection device so that the projected image is focused on the projection surface based on the distance measured by the distance sensor; a projection image correction unit that corrects the projection image so that the size and aspect ratio of the captured image captured by the capturing camera become desired values; A remotely operated underwater vehicle comprising:

3. 3. The remote-operated underwater vehicle of claim 2, wherein the projection image correction unit determines a maximum rectangular area of ​​a trapezoidal captured image taken during movement that overlaps with a rectangular captured image taken in a horizontal state, determines an excess area other than the maximum rectangular area in the rectangular captured image, removes the excess area from the projection image, and corrects the projection image so that the projection image after removal is zoomed in according to the size of the rectangular captured image.

4. a spectroscopic means for spectroscopically separating blue light contained in light emitted by the light source, 4. The remote-operated underwater vehicle according to claim 2, wherein the distance sensor detects the distance from the projection device to a projection surface by emitting the blue light split by the splitting means to the projection surface.

5. 5. The remote-operated underwater vehicle according to claim 1, wherein the frame body is provided with an underwater screw and a support arm for supporting the underwater screw on its outer periphery.

6. The remote-operated underwater vehicle of claim 5, wherein the underwater screw comprises a first drive screw for moving the remote-operated underwater vehicle forward, backward or left and right, and a second drive screw for moving the remote-operated underwater vehicle up and down.

7. 6. The remote-operated underwater vehicle according to claim 5, wherein the support arm is provided with a rotation mechanism for rotating the rotation axis of the underwater screw about an axis perpendicular to the rotation axis.

8. the projection device includes a spatial light modulator that modulates the light sent from the light source to form an image, and a projection lens that sends the light from the spatial light modulator to the projection surface; the frame body is provided with an underwater screw and a support arm for supporting the underwater screw on an outer periphery thereof, and the frame body is provided with the projection device, the light source, and the heat dissipation mechanism therein; the water pipe is formed to pass through the frame body in a projection direction of the projection device to cool the light source; The remote-operated underwater vehicle according to claim 2 , wherein the heat dissipation mechanism includes a rod lens that transmits light from the light source to the spatial light modulator.

9. The remote-controlled underwater vehicle described in claim 1 or claim 2, wherein the projection device comprises a rod lens that is arranged to penetrate the center of the heat dissipation mechanism and transmits light from the light source, a spatial light modulator that modulates the light from the rod lens, a projection lens that transmits the light modulated by the spatial light modulator to become the projected image to a projection surface, and a lens adjustment mechanism that adjusts the focus by moving the position of the projection lens along the optical axis.

10. 10. The remote-operated underwater vehicle according to claim 9, wherein the spatial light modulator is a digital micromirror device that aligns reflecting mirrors and controls the angles of the reflecting mirrors in accordance with the image.

11. 10. The remote-controlled underwater vehicle according to claim 9, wherein the spatial light modulator is a reflective or transmissive liquid crystal element.

12. The frame body has a water flow pipe that penetrates in the front-to-rear direction on either the left or right side based on the center in the left-to-right direction, and a second water flow pipe that penetrates in the front-to-rear direction on the other side.

13. A cooling method for a projection device mounted on a remote-controlled underwater vehicle having a waterproof function, the cooling method comprising: a projection device for displaying a projected image on an external projection surface; a projection image correction unit for correcting the projected image; a light source used in the projection device; a heat dissipation mechanism for dissipating heat from the light source; and a running water pipe for cooling the light source, the running water pipe being provided to penetrate the frame body; a photographing camera for photographing the projected image displayed on the projection surface as a photographed image; a temperature sensor for measuring the temperature of the light source; and a distance sensor for measuring the distance to the projection surface, a movement control unit that moves the remote-controlled underwater vehicle along the axial direction of the water pipe when the temperature measured by the temperature sensor exceeds a predetermined threshold value; a focus control unit that controls the projection device so that the projected image is focused on the projection surface based on the distance measured by the distance sensor; A cooling method for a projection device mounted on a remote-controlled underwater vehicle, the projection image correction unit correcting the projected image so that the size and aspect ratio of the image captured by the photographing camera become desired values.

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