Fault Detection Method and Fault Detection Device

Abstract

To provide a failure detection method capable of detecting a rudder failure of an underwater traveling vehicle with an excellent detecting ability.SOLUTION: A failure detection method of one aspect includes a first step, a second step, and a third step. The first step measures a roll angle of an underwater traveling vehicle traveling with a specific pitch angle and a specific yaw angle under a test environment where the normality of multiple rudders is confirmed, the second step measures the roll angle of the underwater traveling vehicle traveling with the specific pitch angle and the specific yaw angle under an operational environment where the normality of multiple rudders is unconfirmed, and the third step detects one rudder failure of multiple rudders based on the difference between the roll angle of the underwater traveling vehicle measured under the test environment and the roll angle of the underwater traveling vehicle measured under the operational environment.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present disclosure relates to a rudder failure detection method and a failure detection device.

Background Art

[0002] Patent Document 1 describes a vehicle equipped with a plurality of attitude control rudders, a plurality of rudder drive sources for controlling the plurality of attitude control rudders, and failure detection means for detecting failures of the plurality of rudder drive sources. When the current value of the output signal from the rudder drive source becomes equal to or less than a predetermined threshold value, or when the change angle of the rotation angle per unit time of the rudder drive source is equal to or greater than the upper limit value or equal to or less than the lower limit value, etc., it is determined that a failure has occurred in the plurality of rudder drive sources.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Since the failure detection means described in Patent Document 1 detects the failure of the rudder drive source based on the output of the rudder drive source, it is difficult to detect a failure that occurs in the attitude control rudder steered by the rudder drive source. Further, since the above-described failure detection means assumes that the output from the rudder drive source is correct, it may not be able to appropriately detect a failure of the rudder drive source when the output of the rudder drive source is not normal.

[0005] Therefore, an object of the present disclosure is to provide a failure detection method capable of detecting a failure of a rudder of an underwater vehicle with excellent detection ability.

Means for Solving the Problems

[0006] In one aspect, a fault detection method for detecting a fault in a rudder of a submersible vehicle having a plurality of rudders is provided. This fault detection method includes a first step of measuring a roll angle of a submersible vehicle traveling at a specific pitch angle or a specific yaw angle in a test environment where the normality of the plurality of rudders has been confirmed, a second step of measuring a roll angle of a submersible vehicle traveling at a specific pitch angle or a specific yaw angle in an operation environment where the normality of the plurality of rudders has not been confirmed, and a third step of detecting a fault in one of the plurality of rudders based on the difference between the roll angle of the submersible vehicle measured in the test environment and the roll angle of the submersible vehicle measured in the operation environment.

[0007] If there is a difference between the roll angle of the submersible vehicle measured in the test environment and the roll angle of the submersible vehicle measured in the operation environment, it is assumed that the operation of the plurality of rudders in the operation environment is different from the operation of the plurality of rudders in the test environment. Therefore, according to the fault detection method of this aspect, a fault in the rudder can be detected based on the difference between the roll angle of the submersible vehicle measured in the test environment and the roll angle of the submersible vehicle measured in the operation environment. Also, in this method, by detecting a fault in the rudder of the submersible vehicle based on the difference in the measured attitude of the submersible vehicle, a fault in the rudder can be detected even when the measured values of the rudder angles of the plurality of rudders are inaccurate. Therefore, a fault in the rudder of the submersible vehicle can be detected with excellent detection ability.

[0008] In one embodiment, a plurality of rudders include a pair of left and right rudders for adjusting the pitch angle of an underwater vehicle and a pair of upper and lower rudders for adjusting the yaw angle of the underwater vehicle. In the first step, measure a first roll angle, which is the roll angle of the underwater vehicle traveling at a specific pitch angle in a test environment, and measure a second roll angle, which is the roll angle of the underwater vehicle traveling at a specific yaw angle in the test environment. In the second step, measure a third roll angle, which is the roll angle of the underwater vehicle traveling at a specific pitch angle in an operating environment, and measure a fourth roll angle, which is the roll angle of the underwater vehicle traveling at a specific yaw angle in the operating environment. In the third step, if the difference between the first roll angle and the third roll angle is greater than a first threshold, it may be determined that a failure has occurred in one of the pair of left and right rudders, and if the difference between the second roll angle and the fourth roll angle is greater than a second threshold, it may be determined that a failure has occurred in one of the pair of upper and lower rudders.

[0009] If the difference between the first roll angle measured in the test environment and the third roll angle measured in the operating environment is greater than the first threshold, it is highly likely that one of the pair of left and right rudders is not operating normally and its rudder angle is fixed. On the other hand, if the difference between the second roll angle measured in the test environment and the fourth roll angle measured in the operating environment is greater than the second threshold, it is highly likely that one of the pair of upper and lower rudders is not operating normally and its rudder angle is fixed. In this embodiment, by determining that a failure has occurred in one of the pair of left and right rudders when the difference between the first roll angle and the third roll angle is greater than the first threshold, and determining that a failure has occurred in one of the pair of upper and lower rudders when the difference between the second roll angle and the fourth roll angle is greater than the second threshold, it is possible to detect the fixing of the rudder.

[0010] A failure detection method according to one embodiment sets the rudder angle of one of the pair of upper and lower rudders of an underwater vehicle to δ a1 and sets the rudder angle of the other of the pair of upper and lower rudders to -δ a1 , a step of changing the rudder angle δ a1 by a certain angle, and a step of changing the rudder angle δ a1a step of generating first correlation data indicating the relationship with the roll angle of the underwater vehicle; a step of determining correction rudder angles for a pair of upper and lower rudders that reduce the difference between the first roll angle and the third roll angle using the first correlation data; a step of correcting the rudder angles of the pair of upper and lower rudders based on the determined correction rudder angles of the pair of upper and lower rudders; and for one of the pair of left and right rudders of the underwater vehicle, setting the rudder angle to δ a2 and setting the rudder angle of the other of the pair of left and right rudders to -δ a2 ; a step of changing the rudder angle δ a2 by a fixed angle; a step of generating second correlation data indicating the relationship between the rudder angle δ a2 and the roll angle of the underwater vehicle; a step of determining correction rudder angles for a pair of left and right rudders that reduce the difference between the second roll angle and the fourth roll angle using the second correlation data; and a step of correcting the rudder angles of the pair of left and right rudders based on the determined correction rudder angles of the pair of left and right rudders may be further included.

[0011] In the present embodiment, correction rudder angles for a pair of upper and lower rudders that reduce the difference between the first roll angle and the third roll angle are determined, and the rudder angles of the pair of upper and lower rudders are corrected based on the correction rudder angles. Also, correction rudder angles for a pair of left and right rudders that reduce the difference between the second roll angle and the fourth roll angle are determined, and the rudder angles of the pair of left and right rudders are corrected based on the correction rudder angles. As described above, by correcting the rudder angles of a plurality of rudders, the roll angle of the underwater vehicle can be made closer to the normal roll angle. Therefore, even when a failure occurs in the rudder in an operating environment, the underwater vehicle can continue to be operated.

[0012] In one embodiment, the plurality of rudders include a pair of left and right rudders that adjust the pitch angle of the underwater vehicle and a pair of upper and lower rudders that adjust the yaw angle of the underwater vehicle. In the first step, in a test environment, the first roll angle Φ1 of the underwater vehicle traveling straight horizontally, the rudder angles δ l1 , δ r1 of the pair of left and right rudders, and the rudder angles δ u1 , δ d1 of the pair of upper and lower rudders are measured. In the second step, in an operating environment, the second roll angle Φ2 of the underwater vehicle traveling straight horizontally, the rudder angles δ l2, δ r2 and the rudder angles δ of a pair of upper and lower rudders u2 , δ d2 are measured. In the third step, when (Φ2 - Φ1) is greater than the first threshold, if (δ l2 - δ l1 ) + (δ r2 - δ r1 ) is greater than the second threshold, or if (δ u2 - δ u1 ) + (δ d2 - δ d1 ) is greater than the third threshold, it may be determined that a failure has occurred in one of the plurality of rudders.

[0013] When (Φ2 - Φ1) is greater than the first threshold, if (δ l2 - δ l1 ) + (δ r2 - δ r1 ) is greater than the second threshold, or if (δ u2 - δ u1 ) + (δ d2 - δ d1 ) is greater than the third threshold, there is a high possibility that an angular deviation (offset angle) has occurred between the commanded rudder angle and the actual rudder angle of one of the plurality of rudders. In this embodiment, when there is a high possibility that an offset angle exists in one of the plurality of rudders, it is determined that a failure has occurred in the one rudder, so that the failure of the rudder can be detected with excellent detection ability.

[0014] A failure detection method according to an embodiment measures the third roll angle Φ3, which is the roll angle of the underwater vehicle when, in a test environment, the rudder angle of one of the pair of left and right rudders of the underwater vehicle traveling straight ahead horizontally is increased by an angle δ b1 and the rudder angle of the other of the pair of left and right rudders is decreased by an angle δ b1 . The first roll angle Φ1, the second roll angle Φ2, the third roll angle Φ3, the rudder angles δ l1 , δ r1 of the pair of left and right rudders measured in the test environment, the rudder angles δ l2 , δ r2 of the pair of left and right rudders measured in the operation environment, and the angle δ b1Based on this, a step of calculating the offset angle of the rudder angles of a pair of left and right rudders, a step of correcting the rudder angles of the pair of left and right rudders based on the offset angle of the rudder angles of the pair of left and right rudders, and in a test environment, for one of the pair of upper and lower rudders of an underwater vehicle moving straight horizontally, the rudder angle is increased by an angle δ b2 only, and a step of measuring the fourth roll angle Φ4, which is the roll angle of the underwater vehicle when the rudder angle of the other of the pair of upper and lower rudders is decreased by an angle δ b2 only, and the first roll angle Φ1, the second roll angle Φ2, the fourth roll angle Φ4, the rudder angles δ u1 , δ d1 of the pair of upper and lower rudders measured in the test environment, the rudder angles δ u2 , δ d2 of the pair of upper and lower rudders measured in the operating environment, and the angle δ b2 Based on this, a step of calculating the offset angle of the rudder angles of the pair of upper and lower rudders, and a step of correcting the rudder angles of the pair of upper and lower rudders based on the offset angle of the rudder angles of the pair of upper and lower rudders may be further included.

[0015] In this embodiment, since the rudder angles of the pair of left and right rudders and the pair of upper and lower rudders are corrected based on the offset angles of the rudder angles of the pair of left and right rudders and the pair of upper and lower rudders, the actual rudder angles of the plurality of rudders can be made closer to the desired rudder angles. Therefore, even when a failure occurs in the rudder in the operating environment, it is possible to continue operating the underwater vehicle.

[0016] In another aspect, a fault detection method for detecting a fault in a rudder of an underwater vehicle having a plurality of rudders is provided. This fault detection method includes a step of measuring the rudder angles of a plurality of rudders of an underwater vehicle moving at a specific pitch angle or a specific yaw angle in a test environment where the normality of the plurality of rudders has been confirmed, a step of measuring the rudder angles of a plurality of rudders of an underwater vehicle moving at a specific pitch angle or a specific yaw angle in an operating environment where the normality of the plurality of rudders has not been confirmed, and a step of detecting a fault in one of the plurality of rudders based on the rudder angles of the plurality of rudders measured in the test environment and the rudder angles of the plurality of rudders measured in the operating environment.

[0017] If there is a difference between the rudder angles of a plurality of rudders measured in a test environment and the rudder angles of the plurality of rudders measured in an operating environment, damage such as chips may occur in the rudders, and there may be a difference in the lift force of the plurality of rudders. Therefore, in the fault detection method according to this aspect, a fault of the ship can be detected based on the rudder angles of the plurality of rudders measured in the test environment and the rudder angles of the plurality of rudders measured in the operating environment.

[0018] In one aspect, a fault detection device for detecting a fault of a rudder of a submersible vehicle having a plurality of rudders is provided. This fault detection device acquires the roll angle of the submersible vehicle traveling at a specific pitch angle or a specific yaw angle in a test environment where the normality of the plurality of rudders is confirmed, and also acquires the roll angle of the submersible vehicle traveling at a specific pitch angle or a specific yaw angle in an operating environment where the normality of the plurality of rudders is not confirmed. A posture information acquisition unit, and a fault detection unit that detects a fault of one of the plurality of rudders based on the difference between the roll angle of the submersible vehicle acquired in the test environment and the roll angle of the submersible vehicle acquired in the operating environment.

[0019] As described above, according to the fault detection device of this aspect, a fault of the rudder can be detected based on the difference between the roll angle of the submersible vehicle measured in the test environment and the roll angle of the submersible vehicle measured in the operating environment. In addition, the fault detection device can detect a fault of the rudder of the submersible vehicle based on the difference in the measured posture of the submersible vehicle, and thus can detect a fault of the rudder even when the measured values of the rudder angles of the plurality of rudders are inaccurate. Therefore, a fault of the rudder of the submersible vehicle can be detected with excellent detection ability.

[0020] In one embodiment, the plurality of rudders includes a pair of left and right rudders that adjust the pitch angle of the underwater vehicle, and a pair of upper and lower rudders that adjust the yaw angle of the underwater vehicle. The attitude information acquisition unit acquires a first roll angle, which is the roll angle of the underwater vehicle traveling at a specific pitch angle in a test environment, and a second roll angle, which is the roll angle of the underwater vehicle traveling at a specific yaw angle in the test environment. At the same time, it acquires a third roll angle, which is the roll angle of the underwater vehicle traveling at a specific pitch angle in an operating environment, and a fourth roll angle, which is the roll angle of the underwater vehicle traveling at a specific yaw angle in the operating environment. The failure detection unit may determine that a failure has occurred in one of the pair of left and right rudders when the difference between the first roll angle and the third roll angle is greater than a first threshold value, and determine that a failure has occurred in one of the pair of upper and lower rudders when the difference between the second roll angle and the fourth roll angle is greater than a second threshold value.

[0021] When the difference between the first roll angle measured in the test environment and the third roll angle measured in the operating environment is greater than a predetermined threshold value, it is highly likely that one of the pair of left and right rudders is not operating normally and its rudder angle is fixed. On the other hand, when the difference between the second roll angle measured in the test environment and the fourth roll angle measured in the operating environment is greater than a predetermined threshold value, it is highly likely that one of the pair of upper and lower rudders is not operating normally and its rudder angle is fixed. In this embodiment, by determining that a failure has occurred in one of the pair of left and right rudders when the difference between the first roll angle and the third roll angle is greater than the first threshold value, and determining that a failure has occurred in one of the pair of upper and lower rudders when the difference between the second roll angle and the fourth roll angle is greater than the second threshold value, it is possible to detect the fixing of the rudder.

[0022] The failure detection device according to one embodiment further includes a rudder angle control unit that controls the rudder angles of the plurality of rudders and a correction unit that corrects the rudder angles of the plurality of rudders. The rudder angle control unit sets the rudder angle of one of the pair of upper and lower rudders of the underwater vehicle to δ a1 and sets the rudder angle of the other of the pair of upper and lower rudders to -δ a1 and changes the rudder angle δ a1 by a certain angle at a time. The failure detection unit uses the rudder angle δ a1generate first correlation data indicating the relationship with the roll angle of the underwater vehicle, and the correction unit uses the first correlation data to determine correction rudder angles for a pair of upper and lower rudders that reduce the difference between the first roll angle and the third roll angle, correct the rudder angles of the pair of upper and lower rudders based on the determined correction rudder angles for the pair of upper and lower rudders, and the rudder angle control unit sets the rudder angle of one of the pair of left and right rudders of the underwater vehicle to δ a2 and sets the rudder angle of the other of the pair of left and right rudders to -δ a2 , and changes the rudder angle δ a2 by a certain angle each time. The failure detection unit generates second correlation data indicating the relationship between the rudder angle δ a2 and the roll angle of the underwater vehicle, and the correction unit uses the second correlation data to determine correction rudder angles for the pair of left and right rudders that reduce the difference between the second roll angle and the fourth roll angle, and may correct the rudder angles of the pair of left and right rudders based on the determined correction rudder angles for the pair of left and right rudders.

[0023] In this embodiment, correction rudder angles for a pair of upper and lower rudders that reduce the difference between the first roll angle and the third roll angle are determined, and the rudder angles of the pair of upper and lower rudders are corrected based on the correction rudder angles. At the same time, correction rudder angles for a pair of left and right rudders that reduce the difference between the second roll angle and the fourth roll angle are determined, and the rudder angles of the pair of left and right rudders are corrected based on the correction rudder angles. As described above, by correcting the rudder angles of multiple rudders, the roll angle of the underwater vehicle can be made closer to the normal roll angle. Therefore, even when a failure occurs in the rudder in the operating environment, the underwater vehicle can continue to be operated.

[0024] In one embodiment, the multiple rudders include a pair of left and right rudders for adjusting the pitch angle of the underwater vehicle and a pair of upper and lower rudders for adjusting the yaw angle of the underwater vehicle. The attitude information acquisition unit acquires the first roll angle Φ1 of the underwater vehicle traveling straight ahead horizontally in the test environment, the rudder angles δ l1 , δ r1 of the pair of left and right rudders, and the rudder angles δ u1 , δ d1 of the pair of upper and lower rudders. At the same time, it acquires the second roll angle Φ2 of the underwater vehicle traveling straight ahead horizontally in the operating environment, the rudder angles δ l2 , δ r2 of the pair of left and right rudders, and the rudder angles δu2 , δ d2 is obtained, and when (Φ2 - Φ1) is greater than the first threshold value, the failure detection unit determines that a failure has occurred in one of the plurality of rudders when ((δ l2 - δ l1 ) + (δ r2 - δ r1 ) is greater than the second threshold value, or when ((δ u2 - δ u1 ) + (δ d2 - δ d1 ) is greater than the third threshold value.

[0025] When (Φ2 - Φ1) is greater than the first threshold value, when ((δ l2 - δ l1 ) + (δ r2 - δ r1 ) is greater than the second threshold value, or when ((δ u2 - δ u1 ) + (δ d2 - δ d1 ) is greater than the third threshold value, there is a high possibility that an angular deviation (offset angle) occurs between the commanded rudder angle and the actual rudder angle of one of the plurality of rudders. In this embodiment, when there is a high possibility that an offset angle exists in one of the plurality of rudders, it is determined that a failure has occurred in the one rudder, so that the failure of the rudder can be detected with excellent detection ability.

[0026] The failure detection device according to an embodiment further includes a correction unit that corrects the rudder angles of a plurality of rudders. The attitude information acquisition unit acquires, in a test environment, the third roll angle Φ3, which is the roll angle of the underwater vehicle when the rudder angle of one of the left and right pair of rudders of the underwater vehicle traveling straight ahead horizontally is increased by an angle δ b1 and the rudder angle of the other of the left and right pair of rudders is decreased by an angle δ b1 . The failure detection unit includes the first roll angle Φ1, the second roll angle Φ2, the third roll angle Φ3, the rudder angles δ l1 , δ r1 of the left and right pair of rudders measured in the test environment, the rudder angles δ l2 , δ r2 of the left and right pair of rudders measured in the operation environment, and the angle δ b1Based on this, the offset angle of the rudder angles of a pair of left and right rudders is calculated, and the correction unit corrects the rudder angles of the pair of left and right rudders based on the offset angle of the rudder angles of the pair of left and right rudders. The attitude information acquisition unit, in a test environment, sets the rudder angle of one of the pair of upper and lower rudders of the underwater vehicle traveling straight horizontally to be increased by an angle δ b2 only, and obtains the fourth roll angle Φ4 which is the roll angle of the underwater vehicle when the rudder angle of the other of the pair of upper and lower rudders is decreased by an angle δ b2 only. The failure detection unit calculates the offset angle of the rudder angles of the pair of upper and lower rudders based on the first roll angle Φ1, the second roll angle Φ2, the fourth roll angle Φ4, the rudder angles δ u1 , δ d1 of the pair of upper and lower rudders measured in the test environment, the rudder angles δ u2 , δ d2 of the pair of upper and lower rudders measured in the operation environment, and the angle δ b2 , and the correction unit may correct the rudder angles of the pair of upper and lower rudders based on the offset angle of the rudder angles of the pair of upper and lower rudders.

[0027] In this embodiment, since the rudder angles of the pair of left and right rudders and the pair of upper and lower rudders are corrected based on the offset angles of the rudder angles of the pair of left and right rudders and the pair of upper and lower rudders, the actual rudder angles of the plurality of rudders can be made closer to the desired rudder angles. Therefore, even when a failure occurs in the rudder in the operation environment, the underwater vehicle can continue to be operated.

[0028] In one aspect, a failure detection device for detecting a failure of a rudder of an underwater vehicle having a plurality of rudders is provided. This failure detection device acquires the rudder angles of a plurality of rudders of an underwater vehicle traveling at a specific pitch angle or a specific yaw angle in a test environment where the normality of the plurality of rudders has been confirmed, and also acquires the rudder angles of a plurality of rudders of an underwater vehicle traveling at a specific pitch angle or a specific yaw angle in an operation environment where the normality of the plurality of rudders has not been confirmed. It includes a rudder angle acquisition unit for acquiring, and a failure detection unit for detecting a failure of one of the plurality of rudders based on the rudder angles of the plurality of rudders acquired in the test environment and the rudder angles of the plurality of rudders acquired in the operation environment.

[0029] If there is a difference between the rudder angles of a plurality of rudders measured in a test environment and the rudder angles of the plurality of rudders measured in an operating environment, there may be a breakage such as a chip in the rudder, and there may be a difference in the lift force of the plurality of rudders. Therefore, the failure detection device according to this aspect can detect a failure of the ship based on the rudder angles of the plurality of rudders measured in the test environment and the rudder angles of the plurality of rudders measured in the operating environment.

Effect of the Invention

[0030] According to one aspect and various embodiments of the present invention, it is possible to detect a failure of the rudder of an underwater vehicle with excellent detection ability.

Brief Description of the Drawings

[0031]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Modes for Carrying Out the Invention

[0032] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. In the following description, the same or corresponding elements are denoted by the same reference numerals, and redundant descriptions will not be repeated. The drawings may be drawn with some parts simplified or exaggerated for ease of understanding, and dimensional ratios, angles, etc. are not limited to those shown in the drawings. For convenience of explanation, an XYZ orthogonal coordinate system is shown in the drawings. The X-axis direction coincides with the longitudinal direction of the underwater vehicle, the Y-axis direction coincides with the lateral direction of the underwater vehicle, and the Z-axis direction coincides with the vertical direction of the underwater vehicle. is used.

[0033] First, an underwater vehicle to which a fault detection method according to an embodiment is applied will be described. The underwater vehicle 1 is, for example, an unmanned robot for underwater exploration, and autonomously navigates underwater to explore the seabed using various sensors such as sonar.

[0034] FIG. 1(a) is a side view of an exemplary underwater vehicle 1 to which the fault detection method is applied, and FIG. 1(b) is a rear view of the underwater vehicle 1. FIG. 2 is a block diagram showing the functional configuration of the underwater vehicle 1. As shown in FIGS. 1 and 2, the underwater vehicle 1 includes a hull 2, a propulsion unit 3, a plurality of rudders 4, an INS (Inertial Navigation System) 5, and a control device 10.

[0035] The propulsion unit 3 applies a propulsion force to the hull 2. The propulsion unit 3 includes a thruster 31 and a propulsion drive unit 32. The thruster 31 is a device that generates a propulsion force, such as a propeller or a thruster, and is disposed at the rear end of the hull 2. The propulsion drive unit 32 is an actuator that drives the thruster 31. As the propulsion drive unit 32, for example, an electric motor that is driven by receiving power from a battery mounted on the underwater vehicle 1 is used.

[0036] The plurality of rudders 4 control the attitude of the underwater vehicle 1. The plurality of rudders 4 are, for example, cross rudders, and include four rudders: a left rudder 4l, a right rudder 4r, an upper rudder 4u, and a lower rudder 4d. Among these plurality of rudders 4, a pair of left and right rudders 4l, 4r adjust the pitch angle (angle around the Y-axis) of the underwater vehicle. A pair of upper and lower rudders 4u, 4d adjust the yaw angle (angle around the Z-axis) of the underwater vehicle 1.

[0037] As shown in FIG. 2, each of the plurality of rudders 4 includes a rudder body 41 and a rudder drive unit 42. The rudder body 41 is a plate-shaped member having an airfoil shape and is disposed at the rear end of the hull 2. As shown in FIG. 1(b), the rudder bodies 41 of the plurality of rudders 4 are respectively disposed at positions of 0°, 90°, 180°, and 270° in the circumferential direction around the X-axis. Each rudder body 41 is configured to be rotatable so as to have a desired angle of attack with respect to the water flow direction, and generates a rudder lift force in a direction perpendicular to the traveling direction of the hull 2. That is, the pitch angle and yaw angle of the underwater vehicle 1 are controlled by adjusting the rudder angles (angles of attack) of the rudder bodies 41 of the pair of left and right rudders 4l, 4r and the rudder angles (angles of attack) of the rudder bodies 41 of the pair of upper and lower rudders 4u, 4d. In one embodiment, auxiliary wings such as flaps may be provided on the rudder body 41, and the angle of attack of the auxiliary wings may be configured to be changeable.

[0038] The rudder drive unit 42 is an actuator that drives the rudder body 41. As the rudder drive unit 42, for example, a servo motor driven by electric power received from a battery is used. The rudder drive unit 42 receives a control signal from the control device 10 and controls the rudder angle of the corresponding rudder body 41 to a specified command rudder angle. In addition, the rudder drive unit 42 outputs a measured value of the actual rudder angle of the corresponding rudder body 41. By controlling the rudder angles of the rudder bodies 41 by the rudder drive units 42 of the plurality of rudders 4 respectively, the pitch angle and yaw angle of the underwater vehicle 1 are controlled, and as a result, the underwater vehicle 1 can dive, surface, or turn left and right.

[0039] Incidentally, the underwater vehicle 1 may further include a buoyancy adjustment device that adjusts the pitch angle of the underwater vehicle 1, or a weight moving device that changes the center of gravity position of the underwater vehicle 1. The buoyancy adjustment device adjusts the attitude of the underwater vehicle by injecting or discharging ballast water, for example. The weight moving device changes the center of gravity position by moving a weight disposed inside the underwater vehicle 1, for example.

[0040] INS5 is a device that measures the attitude information and position information of the underwater vehicle 1. INS5 includes an acceleration sensor 51 and a gyro sensor 52, and has a function of measuring the angular velocity around three axes. Specifically, INS5 obtains the pitch angle, yaw angle, and roll angle of the underwater vehicle 1 as attitude information from the angular velocity around the three axes of the underwater vehicle 1 measured by the gyro sensor 52. Further, INS5 calculates the position information of the underwater vehicle 1 by double integrating the acceleration information in the three-axis directions measured by the acceleration sensor 51. INS5 outputs the measured attitude information and position information of the underwater vehicle 1 to the control device 10.

[0041] The control device 10 controls the propulsion unit 3 and the plurality of rudders 4 to make the underwater vehicle 1 travel. Further, the control device 10 functions as a failure detection device that detects the failure of the rudder 4 of the underwater vehicle 1. The control device 10 is mainly configured by a computer including a CPU, a ROM, and a RAM, for example, and a computer program for realizing a predetermined function is stored in the ROM or the like. Then, by loading the above computer program onto the CPU and the RAM and operating it under the control of the CPU, various functions described later are realized. Incidentally, in one embodiment, each function of the control device 10 may be realized by an integrated circuit.

[0042] As shown in FIG. 2, the control device 10 includes, as a functional configuration, a target value determination unit 11, a position information acquisition unit 12, an attitude information acquisition unit 13, a rudder angle acquisition unit 14, a storage unit 15, an actuator control unit 16, a failure detection unit 17, and a correction unit 18.

[0043] The target value determination unit 11 determines the target position and target attitude of the underwater vehicle 1. The target position is the target value of the position of the underwater vehicle 1 at a future time point. The target attitude is the target value of the attitude information (for example, pitch angle, yaw angle, and roll angle) of the underwater vehicle 1 at a future time point. For example, the target value determination unit 11 reads the target position and target attitude for each time from the storage unit 15 and determines the target position and target attitude of the underwater vehicle 1 at a certain future time point.

[0044] The position information acquisition unit 12 acquires the position information of the underwater vehicle 1 measured by the INS 5 and outputs the acquired position information to the actuator control unit 16 and the failure detection unit 17. The attitude information acquisition unit 13 acquires the attitude information measured by the INS 5, that is, the pitch angle, yaw angle, and roll angle of the underwater vehicle 1, and outputs the acquired attitude information to the actuator control unit 16 and the failure detection unit 17. The rudder angle acquisition unit 14 acquires the measured values of the rudder angles of the plurality of rudders 4 based on the outputs of the rudder drive units 42 of the plurality of rudders 4. The rudder angle acquisition unit 14 outputs the acquired rudder angles of the plurality of rudders 4 to the actuator control unit 16 and the failure detection unit 17.

[0045] The storage unit 15 is a database that stores the motion information of the underwater vehicle 1. For example, the storage unit 15 stores the position information of the underwater vehicle 1, the attitude information of the underwater vehicle 1, and the measured values of the rudder angles of the plurality of rudders 4 measured by the position information acquisition unit 12, the attitude information acquisition unit 13, and the rudder angle acquisition unit 14 in association with the measurement time. In addition, the target position and target attitude of the underwater vehicle 1 at each time are stored in the storage unit 15.

[0046] The actuator control unit 16 functions as a rudder angle control unit that controls the rudder angles of the plurality of rudders 4. The actuator control unit 16 acquires the target position and target attitude from the target value determination unit 11, and also acquires the position information and attitude information of the underwater vehicle 1 from the position information acquisition unit 12 and the attitude information acquisition unit 13. Then, the actuator control unit 16 controls the propulsion unit 3 and the plurality of rudders 4 so that the position and attitude of the underwater vehicle 1 approach the target position and target attitude. For example, based on the difference between the current attitude of the underwater vehicle 1 and the target attitude, the actuator control unit 16 calculates the moments in the three-axis directions for bringing the underwater vehicle 1 to the target attitude, and determines the propulsion force of the propulsion unit 3 and the rudder angles of the plurality of rudders 4 for generating the calculated moments in the three-axis directions. Then, the propulsion unit 3 and the plurality of rudders 4 are controlled so that the propulsion force of the propulsion unit 3 and the rudder angles of the plurality of rudders 4 become the determined propulsion force and rudder angles. As a result, a rudder lift force corresponding to the rudder angles of the plurality of rudders 4 is generated, and moments around the X-axis, Y-axis, and Z-axis are generated. Consequently, the underwater vehicle 1 turns to the target pitch angle, yaw angle, and roll angle, and the underwater vehicle 1 travels toward the target position.

[0047] The failure detection unit 17 detects a failure of one of the plurality of rudders 4. For example, the failure detection unit 17 detects a failure of one of the plurality of rudders 4 based on the difference between the roll angle of the underwater vehicle 1 traveling at a specific pitch angle or a specific yaw angle in a test environment where the normality of the plurality of rudders 4 has been confirmed and the roll angle of the underwater vehicle 1 traveling at a specific pitch angle or a specific yaw angle in an operation environment where the normality of the plurality of rudders 4 has not been confirmed. Here, the test environment where the normality of the plurality of rudders 4 has been confirmed refers to an environment where it has been previously confirmed that no failure has occurred in the plurality of rudders 4, and the operation environment where the normality of the plurality of rudders 4 has not been confirmed refers to an environment where it is unknown whether a failure has occurred in the plurality of rudders 4. When the failure detection unit 17 detects a failure of the rudder 4, it outputs failure detection information indicating that a failure has occurred in the rudder 4 to the correction unit 18. Details of the method for detecting a failure of the rudder 4 by the failure detection unit 17 will be described later.

[0048] When the correction unit 18 receives failure detection information from the failure detection unit 17, it corrects the rudder angles of the plurality of rudders 4. When a failure occurs in one of the plurality of rudders 4, the correction unit 18 corrects the rudder angles of the plurality of rudders 4 to enable the continuation of a mission such as a subsea exploration. Details of the method for correcting the rudder angles of the plurality of rudders 4 by the correction unit 18 will be described later. Note that when failure detection information is output from the failure detection unit 17, the actuator control unit 16 may abort the mission such as a subsea exploration and cause the underwater vehicle 1 to surface. In this case, the control device 10 of the underwater vehicle 1 may not include the correction unit 18.

[0049] (First Embodiment) Next, a method for detecting a failure of a rudder according to the first embodiment will be described, and details of the functions of the control device 10 will be described. The failure detection method described below is executed using the underwater vehicle 1 shown in FIG. 2. FIG. 3 is a flowchart showing a failure detection method MT1 according to the first embodiment. This method MT1 is a method for detecting that one of a pair of left and right rudders 4l, 4r does not operate normally and its rudder angle is fixed at a certain angle.

[0050] In the failure detection method MT1, first, a preparation step ST11 is performed. The preparation step ST11 is a step for acquiring the motion information of the underwater vehicle 1 in a normal state. The preparation step ST11 includes steps ST101 to ST106. These steps ST101 to ST106 are performed in a test environment in which the normality of the plurality of rudders 4 is confirmed.

[0051] In the preparation step ST11, first, the underwater vehicle 1 is made to travel at a specific pitch angle in a test environment (step ST101). The specific pitch angle may be a pitch angle at which the underwater vehicle 1 dives, a pitch angle at which the underwater vehicle 1 travels horizontally, or a pitch angle at which the underwater vehicle 1 surfaces.

[0052] Next, the attitude information acquisition unit 13 of the control device 10 acquires the roll angle (first roll angle) Φ1 of the underwater vehicle 1 traveling straight at a specific pitch angle (step ST102) (first step). The attitude information acquisition unit 13 stores the acquired roll angle Φ1 in the storage unit 15 in association with the specific pitch angle. Next, the rudder angle acquisition unit 14 of the control device 10 acquires the rudder angles δ l1 , δ r1 of the pair of left and right rudders 4l and 4r of the underwater vehicle 1 traveling at a specific pitch angle (step ST103). The rudder angle acquisition unit 14 stores the acquired rudder angles δ l1 , δ r1 in the storage unit 15 in association with the specific pitch angle. At this time, the rudder angle acquisition unit 14 may acquire the rudder angles δ l1 , δ r1 of the pair of left and right rudders 4l and 4r together with the rudder angles δ u1 , δ d1 of the pair of upper and lower rudders 4u and 4d.

[0053] Next, the actuator control unit 16 of the control device 10 sets the rudder angles of the pair of upper and lower rudders 4u and 4d to δ a1 , -δ a1 respectively (step ST104). That is, the pair of upper and lower rudders 4u and 4d are steered in opposite directions with respect to the traveling direction of the underwater vehicle 1. Next, the actuator control unit 16 changes δ a1 by a certain angle (step ST105). For example, the actuator control unit 16 changes the rudder angles (δ a1 , -δ a1 ) of the pair of upper and lower rudders 4u and 4d by 5° each as (25°, -25°), (20°, -20°), (15°, -15°), (10°, -10°), (5°, -5°). At this time, the failure detection unit 17 acquires the roll angle of the underwater vehicle 1 for each rudder angle of the pair of upper and lower rudders 4u and 4d, and generates first correlation data indicating the relationship between the rudder angle δ a1 and the roll angle of the underwater vehicle 1 (step ST106). The generated first correlation data is stored in the storage unit 15.

[0054] When the preparation step ST11 ends, the detection step ST12 is performed. The detection step ST12 detects a failure of the rudder 4 of the underwater vehicle 1 and corrects the rudder angles of the plurality of rudders 4 when a failure of the rudder 4 is detected. The detection step ST12 includes steps ST107 to ST113 described later. Steps ST107 to ST113 are performed in an operating environment where the normality of the plurality of rudders 4 has not been confirmed.

[0055] In the detection step ST12, first, the underwater vehicle 1 is made to travel straight at a specific pitch angle in the operating environment (step ST107). This specific pitch angle is the same angle as the pitch angle of the underwater vehicle 1 that traveled in step ST101. Next, the attitude information acquisition unit 13 of the control device 10 acquires the roll angle (third roll angle) Φ3 of the underwater vehicle 1 traveling at the specific pitch angle (step ST108) (second step). The attitude information acquisition unit 13 stores the acquired roll angle Φ3 in the storage unit 15 in association with the specific pitch angle. Next, the rudder angle acquisition unit 14 of the control device 10 acquires the rudder angles δ l2 ,δ r2 of the pair of left and right rudders 4l, 4r of the underwater vehicle 1 traveling at the specific pitch angle (step ST109). The rudder angle acquisition unit 14 stores the acquired rudder angles δ l2 ,δ r2 in the storage unit 15 in association with the specific pitch angle. At this time, the rudder angle acquisition unit 14 may acquire the rudder angles δ l2 ,δ r2 of the pair of upper and lower rudders 4u, 4d together with the rudder angles δ u2 ,δ d2 of the pair of left and right rudders 4l, 4r.

[0056] Next, the failure detection unit 17 determines whether the difference (|Φ1 - Φ3|) between the roll angle Φ1 measured in the test environment and the roll angle Φ3 measured in the operation environment is greater than a predetermined threshold value (first threshold value) (step ST110). When the difference between the roll angle Φ1 measured in the test environment and the roll angle Φ3 measured in the operation environment is greater than the predetermined threshold value, it is highly likely that the steering angle of one of the pair of left and right rudders 4l, 4r is fixed. Therefore, when |Φ1 - Φ3| is greater than the predetermined threshold value, the failure detection unit 17 determines that a failure has occurred in one of the pair of left and right rudders 4l, 4r and outputs failure detection information (step ST111) (third step).

[0057] In one embodiment, the failure detection unit 17 measures the roll angle Φ3 of the underwater vehicle 1 during horizontal navigation, diving, or surfacing, and the steering angles δ l2 , δ r2 of the pair of left and right rudders 4l, 4r are stable at a constant value, and when |Φ1 - Φ3| is greater than the predetermined threshold value, it may be determined that a failure has occurred in one of the pair of left and right rudders 4l, 4r. On the other hand, when |Φ1 - Φ3| is less than or equal to the predetermined threshold value, it is determined that no failure has occurred in the pair of left and right rudders 4l, 4r, and a series of processes is terminated.

[0058] When the correction unit 18 receives the failure detection information from the failure detection unit 17, it uses the first correlation data generated in step ST106 to reduce the difference between the roll angle Φ1 measured in the test environment and the roll angle Φ3 measured in the operation environment, and determines the correction steering angles δ c1 of the pair of upper and lower rudders 4u, 4d (step ST112). That is, the actuator control unit 16 obtains, from the first correlation data indicating the relationship between the steering angles δ a1 of the pair of upper and lower rudders 4u, 4d and the roll angle of the underwater vehicle 1, the steering angle δ a1 that generates a roll angle that cancels out the difference between the roll angle Φ1 and the roll angle Φ3, and determines the obtained δ a1 as the correction steering angle δ c1

[0059] Next, the correction unit 18 uses the determined correction steering angle δ c1 ​Based on this, the rudder angles of the upper and lower pair of rudders 4u and 4d are corrected (step ST113). For example, the correction unit 18 adds the correction rudder angle δ u2 , δ d2 to the rudder angles δ c1 of the upper and lower pair of rudders 4u and 4d, and the rudder angles of the upper and lower pair of rudders 4u and 4d are respectively (δ u2 + δ c1 ), (δ d2 - δ c1 ). By correcting the rudder angles of the upper and lower pair of rudders 4u and 4d in this way, a moment is generated in the underwater vehicle 1 to cancel the difference between the roll angle Φ1 and the roll angle Φ3, and the roll angle Φ3 of the underwater vehicle 1 approaches the roll angle Φ1 of the normal underwater vehicle 1. By correcting the roll angle of the underwater vehicle 1 in this way, it becomes possible to continue missions such as seabed exploration.

[0060] As described above, in this method MT1, when the difference between the roll angle Φ1 measured in the test environment and the roll angle Φ3 measured in the operation environment is larger than a predetermined threshold value, it is determined that a failure has occurred in one of the pair of left and right rudders 4l and 4r. Therefore, it is possible to detect that the rudder angle of the rudder 4 has been fixed. Also, in this method MT1, since the failure of the rudder 4 of the underwater vehicle 1 is detected based on the difference between the roll angle Φ1 measured in the test environment and the roll angle Φ3 measured in the operation environment, even if the measured values of the rudder angles of the plurality of rudders 4 acquired by the rudder angle acquisition unit 14 are inaccurate, the failure of the rudder can be detected.

[0061] In the method MT1, when a failure of the rudder is detected by the failure detection unit 17, the rudder angles of the upper and lower pair of rudders 4u and 4d are corrected by the correction unit 18. However, in one embodiment, when a failure of the rudder 4 is detected, the operation of the underwater vehicle 1 may be aborted without correcting the rudder angles of the upper and lower pair of rudders 4u and 4d, and the underwater vehicle 1 may be surfaced. In this case, the processes related to the correction of the rudder angle, specifically, steps ST103 to ST106, step ST109, step ST112, and step ST113 may not be performed.

[0062] (Second Embodiment) Next, a rudder failure detection method according to the second embodiment will be described, and the details of the functions of the control device 10 will be described. FIG. 4 is a flowchart showing a failure detection method MT2 according to the second embodiment. This method MT2 is a method for detecting that one of the pair of upper and lower rudders 4u and 4d is not operating normally and its rudder angle is fixed at a certain angle.

[0063] In the failure detection method MT2, first, a preparation step ST21 is performed. The preparation step ST21 is a step for acquiring the normal motion information of the underwater vehicle 1. The preparation step ST21 includes steps ST201 to ST206. Steps ST201 to ST206 are performed in a test environment where the normality of a plurality of rudders 4 is confirmed.

[0064] In the preparation step ST21, first, the underwater vehicle 1 is made to travel at a specific yaw angle in a test environment (step ST201). The specific yaw angle is a yaw angle for turning the underwater vehicle 1 to the right, a yaw angle for turning the underwater vehicle 1 to the left, or a yaw angle for making the underwater vehicle 1 travel straight.

[0065] Next, the attitude information acquisition unit 13 of the control device 10 acquires the roll angle (second roll angle) Φ2 of the underwater vehicle 1 traveling at a specific yaw angle (step ST202) (first step). The attitude information acquisition unit 13 stores the acquired roll angle Φ2 in the storage unit 15 in association with the specific yaw angle. Next, the rudder angle acquisition unit 14 of the control device 10 acquires the rudder angles δ u1 ,δ d1 of the pair of upper and lower rudders 4u and 4d of the underwater vehicle 1 traveling at a specific yaw angle (step ST203). The rudder angle acquisition unit 14 stores the acquired rudder angles δ u1 ,δ d1 in the storage unit 15 in association with the specific yaw angle. At this time, the rudder angle acquisition unit 14 may acquire the rudder angles δ u1 ,δ d1 of the pair of upper and lower rudders 4u and 4d together with the rudder angles δ l1 ,δ r1 of the pair of left and right rudders 4l and 4r.

[0066] Next, the actuator control unit 16 of the control device 10 sets the steering angles of the pair of left and right rudders 4l and 4r to δ a2 , -δ a2 respectively (step ST204). That is, the pair of left and right rudders 4l and 4r are steered in opposite directions with respect to the traveling direction of the underwater vehicle 1. Next, the actuator control unit 16 changes δ a2 by a certain angle (step ST205). For example, the actuator control unit 16 changes the steering angles (δ a2 , -δ a2 ) of the pair of left and right rudders 4l and 4r by 5° each as (25°, -25°), (20°, -20°), (15°, -15°), (10°, -10°), (5°, -5°). At this time, the failure detection unit 17 acquires the roll angle of the underwater vehicle 1 for each steering angle of the pair of left and right rudders 4l and 4r, and generates second correlation data indicating the relationship between the steering angle δ a2 and the roll angle of the underwater vehicle 1 (step ST206). The generated second correlation data is stored in the storage unit 15.

[0067] When the preparation step ST21 is completed, the detection step ST22 is performed. The detection step ST22 detects a failure of the rudder of the underwater vehicle 1 and corrects the steering angles of the plurality of rudders 4 when a failure is detected. The detection step ST22 includes steps ST207 to ST213 described later. Steps ST207 to ST213 are performed in an operating environment where the normality of the plurality of rudders 4 has not been confirmed.

[0068] In the detection step ST22, first, the underwater vehicle 1 is made to travel at a specific yaw angle in the operating environment (step ST207). This specific yaw angle is the same angle as the yaw angle of the underwater vehicle 1 that traveled in step ST201. Next, the attitude information acquisition unit 13 of the control device 10 acquires the roll angle (fourth roll angle) Φ4 of the underwater vehicle 1 traveling at the specific yaw angle (step ST208). The attitude information acquisition unit 13 associates the acquired roll angle Φ4 with the specific yaw angle and stores it in the storage unit 15. Next, the steering angle acquisition unit 14 of the control device 10 acquires the steering angles δ u2 , δ d2To obtain it (step ST209). The rudder angle acquisition unit 14 acquires the acquired rudder angle δ u2 , δ d2 and associates it with a specific yaw angle and stores it in the storage unit 15. At this time, the rudder angle acquisition unit 14 acquires the rudder angles δ u2 , δ d2 of the pair of upper and lower rudders 4u, 4d, and may also acquire the rudder angles δ l2 , δ r2 of the pair of left and right rudders 4l, 4r.

[0069] Next, the failure detection unit 17 determines whether the difference (|Φ2 - Φ4|) between the roll angle Φ2 measured in the test environment and the roll angle Φ4 measured in the operation environment is greater than a predetermined threshold value (second threshold value) (step ST210). If the difference between the roll angle Φ2 measured in the test environment and the roll angle Φ4 measured in the operation environment is greater than the predetermined threshold value, it is highly likely that one of the pair of upper and lower rudders 4u, 4d is in a fixed state. Therefore, when |Φ2 - Φ4| is greater than the predetermined threshold value, the failure detection unit 17 determines that a failure has occurred in one of the pair of upper and lower rudders 4u, 4d and outputs failure detection information (step ST211).

[0070] In one embodiment, when the roll angle Φ4 of the underwater vehicle 1 during horizontal navigation, diving, or surfacing and the rudder angles δ u2 , δ d2 of the pair of upper and lower rudders 4u, 4d are stable at a constant value, and |Φ2 - Φ4| is greater than the predetermined threshold value, it may be determined that a failure has occurred in one of the pair of upper and lower rudders 4u, 4d. On the other hand, when |Φ2 - Φ4| is less than or equal to the predetermined threshold value, it is determined that no failure has occurred in the pair of upper and lower rudders 4u, 4d, and a series of processes ends.

[0071] When the correction unit 18 receives the failure detection information from the failure detection unit 17, it uses the second correlation data generated in step ST206 to reduce the difference between the roll angle Φ2 measured in the test environment and the roll angle Φ4 measured in the operation environment for the pair of left and right rudders 4l, 4r with the correction rudder angle δ c2Determine it (step ST212). That is, the actuator control unit 16 determines the rudder angle δ of the pair of left and right rudders 4l and 4r a2 from the second correlation data indicating the relationship between the roll angle of the underwater vehicle 1 and the roll angle Φ2 and roll angle Φ4 of the underwater vehicle 1, and cancels the difference between the roll angle Φ2 and the roll angle Φ4. a2 Obtain the rudder angle δ, and use the obtained rudder angle δ a2 as the corrected rudder angle δ c2 to determine.

[0072] Next, the correction unit 18 corrects the rudder angles of the pair of left and right rudders 4l and 4r based on the determined corrected rudder angle δ c2 . For example, the correction unit 18 adds the corrected rudder angle δ l2 to the rudder angles δ r2 of the pair of left and right rudders 4l and 4r determined by the actuator control unit 16, and adds the corrected rudder angle δ c2 to each of the rudder angles of the pair of left and right rudders 4l and 4r to correct them to (δ l2 +δ c2 ),(δ r2 -δ c2 ). By correcting the rudder angles of the pair of left and right rudders 4l and 4r in this way, a moment around the X-axis is generated to cancel the difference between the roll angle Φ2 and the roll angle Φ4 of the underwater vehicle 1, and the roll angle Φ4 of the underwater vehicle 1 approaches the roll angle Φ2 of the underwater vehicle 1 during normal operation. By correcting the roll angle of the underwater vehicle 1 in this way, it becomes possible to continue missions such as submarine exploration.

[0073] As described above, in this method MT2, when the difference between the roll angle Φ2 measured in the test environment and the roll angle Φ4 measured in the operation environment is greater than a predetermined threshold, it is determined that a failure has occurred in one of the pair of upper and lower rudders 4u and 4d. Therefore, it is possible to detect that the rudder angle of the rudder 4 is fixed. Further, in this method MT2, since the failure of the rudder 4 of the underwater vehicle 1 is detected based on the difference between the roll angle Φ2 measured in the test environment and the roll angle Φ4 measured in the operation environment, even if the measured values of the rudder angles of the plurality of rudders 4 obtained by the rudder angle acquisition unit 14 are inaccurate, the failure of the rudder 4 can be detected.

[0074] In the method MT2, when the failure detection unit 17 detects a failure of the rudder 4, the correction unit 18 corrects the rudder angles of the pair of left and right rudders 4l and 4r. However, in one embodiment, when a failure of the rudder is detected, the operation of the underwater vehicle 1 may be stopped without correcting the rudder angles of the pair of left and right rudders 4l and 4r, and the underwater vehicle 1 may be surfaced. In this case, the processes related to the correction of the rudder angle, specifically, steps ST203 to ST206, step ST209, step ST212, and step ST213 may not be performed.

[0075] (Third Embodiment) Next, a method for detecting a failure of the rudder according to the third embodiment will be described, and the details of the functions of the control device 10 will be described. FIG. 5 is a flowchart showing a failure detection method MT3 according to the third embodiment. This method MT3 is a method for detecting the presence of an offset angle in a pair of left and right rudders 4l and 4r. The offset angle means the angular deviation between the commanded rudder angle and the actual rudder angle of the rudder 4.

[0076] In the failure detection method MT3, first, a preparation step ST31 is performed. The preparation step ST31 is a step for acquiring the motion information of the underwater vehicle 1 in a normal state. The preparation step ST31 includes steps ST301 to ST306. Steps ST301 to ST306 are performed in a test environment where the normality of a plurality of rudders 4 is confirmed.

[0077] In the preparation step ST31, first, the underwater vehicle 1 is made to travel straight horizontally in a test environment (step ST301). In one embodiment, in order to make the underwater vehicle 1 travel straight horizontally, the pitch angle and the yaw angle of the underwater vehicle 1 are set to specific angles (for example, 0°).

[0078] Next, the attitude information acquisition unit 13 of the control device 10 acquires the roll angle (first roll angle) Φ1 of the underwater vehicle 1 traveling straight horizontally (step ST302). The attitude information acquisition unit 13 stores the acquired roll angle Φ1 in the storage unit 15. Next, the rudder angle acquisition unit 14 of the control device 10 acquires the rudder angles δ l1 , δr1 to obtain it (step ST303). The rudder angle acquisition unit 14 acquires the rudder angles δ l1 , δ r1 of the pair of left and right rudders 4l and 4r and stores them in the storage unit 15.

[0079] Next, the actuator control unit 16 decreases the rudder angle of the left rudder 4l of the underwater vehicle 1 traveling straight horizontally by an angle δ b1 and increases the rudder angle of the right rudder 4r by an angle δ b1 . That is, the rudder angle of the left rudder 4l is set to (δ l1 -δ b1 ), and the rudder angle of the right rudder 4r is set to (δ r1 +δ b1 ). Next, the attitude information acquisition unit 13 measures the roll angle (third roll angle) Φ3 of the underwater vehicle 1 that changes with the change in the rudder angles of the pair of left and right rudders 4l and 4r (step ST305). Then, the failure detection unit 17 calculates the change amount ΔΦ of the roll angle according to the following formula (1) (step ST306).

[0080] ΔΦ = Φ3 - Φ1…(1)

[0081] Next, the failure detection unit 17 calculates the change amount Φ u of the roll angle per 1° of the angle difference based on the following formula (2). The calculated Φ u is stored in the storage unit 15.

[0082] Φ u = ΔΦ / 2δ b1 …(2)

[0083] When the preparation step ST31 ends, the detection step ST32 is performed. The detection step ST32 detects a failure of the underwater vehicle 1 and corrects the rudder angles of a plurality of rudders 4 when a failure is detected. The detection step ST32 includes steps ST307 to ST313 described later. Steps ST307 to ST313 are performed in an operating environment where the normality of a plurality of rudders 4 has not been confirmed.

[0084] In the detection step ST32, first, the underwater vehicle 1 is made to travel straight horizontally in the operating environment (step ST307). Next, the attitude information acquisition unit 13 of the control device 10 acquires the roll angle (second roll angle) Φ2 of the underwater vehicle 1 traveling straight horizontally (step ST308). The attitude information acquisition unit 13 stores the acquired roll angle Φ2 in the storage unit 15. Next, the rudder angle acquisition unit 14 of the control device 10 acquires the rudder angles δ l2 , δ r2 of the pair of left and right rudders 4l, 4r of the underwater vehicle 1 traveling straight horizontally (step ST309). The rudder angle acquisition unit 14 stores the acquired rudder angles δ l2 , δ r2 in the storage unit 15. At this time, in addition to the rudder angles δ l2 , δ r2 of the pair of left and right rudders 4l, 4r, the rudder angle acquisition unit 14 may also acquire the rudder angles δ u2 , δ d2 of the pair of upper and lower rudders 4u, 4d.

[0085] Next, the failure detection unit 17 determines whether or not the following condition 1 or condition 2 is satisfied (step ST310). Condition 1: (Φ2 - Φ1) is greater than the first threshold value TH1 Condition 2: (δ l2 - δ l1 ) + (δ r2 - δ r1 ) is greater than the second threshold value TH2

[0086] If condition 1 or condition 2 is satisfied, there is a high possibility that there is an offset angle in the pair of left and right rudders 4l, 4r. Therefore, when condition 1 or condition 2 is satisfied, the failure detection unit 17 determines that a failure has occurred in one of the pair of left and right rudders 4l, 4r and outputs failure detection information (step ST311). In one embodiment, the failure detection unit 17 may determine that a failure has occurred in one of the pair of left and right rudders 4l, 4r when both condition 1 and condition 2 are satisfied. On the other hand, when condition 1 or condition 2 is not satisfied, it is determined that no failure has occurred in the pair of left and right rudders 4l, 4r, and a series of processes is terminated.

[0087] When the correction unit 18 receives the failure detection information, it calculates the offset angles Δδ of the pair of left and right rudders 4l and 4r l , Δδ r (step ST312). The offset angles Δδ of the pair of left and right rudders 4l and 4r l , Δδ r are calculated from the following equations (3) and (4).

[0088] Δδ l = (B - A) / 2 …(3) Δδ r = (B + A) / 2 …(4)

[0089] Note that A and B in equations (3) and (4) are defined as in the following equations (5) and (6). Therefore, the offset angle is calculated based on the roll angle Φ1, roll angle Φ2, roll angle Φ3, the rudder angles δ of the pair of left and right rudders 4l and 4r measured under the test environment l1 , δ r1 , the rudder angles δ of the pair of left and right rudders 4l and 4r measured under the operating environment l2 , δ r2 , and the angle δ b1 .

[0090] A = Δδ r - Δδ l = (Φ2 - Φ1) / Φ u …(5) B = Δδ r + Δδ l = -{(δ l2 - δ l1 ) + (δ r2 - δ r1 )} …(6)

[0091] Next, the correction unit 18 corrects the rudder angles of the pair of left and right rudders 4l and 4r based on the offset angles Δδ l , Δδ r (step ST313). For example, the correction unit 18 decreases the rudder angles of the pair of left and right rudders 4l and 4r by the offset angles Δδ l , Δδ r . That is, the corrected rudder angles δ of the pair of left and right rudders 4l and 4r l3 , δ r3It is represented by the following formulas (7) and (8).

[0092] δ l3 =δ l2 -Δδ l …(7) δ r3 =δ r2 -Δδ r …(8)

[0093] As described above, in this method MT3, when (Φ2 - Φ1) is greater than the first threshold value TH1, or when ((δ l2 -δ l1 ) + (δ r2 -δ r1 )) is greater than the second threshold value TH2, it is determined that a failure has occurred in one of the pair of left and right rudders 4l, 4r. Therefore, it is possible to detect that there is an offset angle in the pair of left and right rudders. Also, by correcting the pair of left and right rudders 4l, 4r based on the offset angles Δδ l , Δδ r , the actual rudder angles of the pair of left and right rudders 4l, 4r can be made closer to the desired rudder angles. As a result, even when a failure occurs in the pair of left and right rudders 4l, 4r, it is possible to continue the operation of the underwater vehicle 1.

[0094] In the method MT3, when a failure of the rudder is detected by the failure detection unit 17, the rudder angles of the pair of left and right rudders 4l, 4r are corrected by the correction unit 18. However, in one embodiment, when a failure of the rudder is detected, the operation of the underwater vehicle 1 may be stopped without correcting the rudder angles of the pair of left and right rudders 4l, 4r, and the underwater vehicle 1 may be surfaced. In this case, the processes related to the correction of the rudder angles, specifically, steps ST304 to ST306, step ST312, and step ST313 may not be performed.

[0095] (Fourth Embodiment) Next, a rudder failure detection method according to the fourth embodiment will be described, and details of the functions of the control device 10 will be described. FIG. 6 is a flowchart showing a failure detection method MT4 according to the fourth embodiment. This method MT4 is a method for detecting that there are offset angles in a pair of upper and lower rudders 4u and 4d.

[0096] In the failure detection method MT4, first, a preparation step ST41 is performed. The preparation step ST41 is a step for acquiring the motion information of the underwater vehicle 1 during normal operation. The preparation step ST41 includes steps ST401 to ST406. Steps ST401 to ST406 are performed in a test environment where the normality of a plurality of rudders 4 is confirmed.

[0097] In the preparation step ST41, first, the underwater vehicle 1 is made to travel straight horizontally in the test environment (step ST401). In one embodiment, in order to make the underwater vehicle 1 travel straight horizontally, the pitch angle and yaw angle of the underwater vehicle 1 are set to specific angles (for example, 0°).

[0098] Next, the attitude information acquisition unit 13 of the control device 10 acquires the roll angle (first roll angle) Φ1 of the underwater vehicle 1 traveling straight horizontally (step ST402). The attitude information acquisition unit 13 stores the acquired roll angle Φ1 in the storage unit 15. Next, the rudder angle acquisition unit 14 of the control device 10 acquires the rudder angles δ u1 , δ d1 of the pair of upper and lower rudders 4u and 4d of the underwater vehicle 1 traveling straight horizontally (step ST403). The rudder angle acquisition unit 14 stores the rudder angles δ u1 , δ d1 of the pair of upper and lower rudders 4u and 4d in the storage unit 15.

[0099] Next, the actuator control unit 16 decreases the rudder angle of the upper rudder 4u of the underwater vehicle 1 traveling straight horizontally by δ b2 and increases the rudder angle of the lower rudder 4d by δ b2 (step ST404). That is, the rudder angle of the upper rudder 4u is set to (δ u1 - δ b2 ), and the rudder angle of the lower rudder 4d is set to (δ d1 + δ b2) is set. Next, the attitude information acquisition unit 13 measures the roll angle Φ4 (the fourth roll angle) of the underwater vehicle 1 that changes with the rudder angles of the pair of upper and lower rudders 4u and 4d (step ST405). Then, the failure detection unit 17 calculates the change amount ΔΦ of the roll angle according to the following formula (9) (step ST406).

[0100] ΔΦ = Φ4 - Φ1…(9)

[0101] Next, the failure detection unit 17 calculates the change amount Φ of the roll angle per 1° of the angle difference based on the following formula (10). u The calculated Φ u is stored in the storage unit 15.

[0102] Φ u = ΔΦ / 2δ b2 …(10)

[0103] When the preparation step ST41 ends, the detection step ST42 is performed. The detection step ST42 detects a failure of the underwater vehicle 1 and corrects the rudder angles of a plurality of rudders 4 when a failure is detected. The detection step ST42 includes steps ST407 to ST413 described later. Steps ST407 to ST413 are performed in an operating environment where the normality of a plurality of rudders 4 has not been confirmed.

[0104] In the detection step ST42, first, the underwater vehicle 1 is made to travel straight horizontally in the operating environment (step ST407). Next, the attitude information acquisition unit 13 of the control device 10 acquires the roll angle (the second roll angle) Φ2 of the underwater vehicle 1 traveling straight horizontally (step ST408). The attitude information acquisition unit 13 stores the acquired roll angle Φ2 in the storage unit 15. Next, the rudder angle acquisition unit 14 of the control device 10 acquires the rudder angles δ u2 , δ d2 of the pair of upper and lower rudders 4u and 4d of the underwater vehicle 1 traveling straight horizontally (step ST409). The rudder angle acquisition unit 14 stores the acquired rudder angles δ u2 , δ d2 in the storage unit 15. At this time, the rudder angle acquisition unit 14 measures the rudder angles δ u2 , δ d2In addition, the rudder angles δ l2 , δ r2 of a pair of left and right rudders 4l and 4r may be acquired.

[0105] Next, the failure detection unit 17 determines whether or not the following condition 1 or condition 2 is satisfied (step ST410). Condition 1: (Φ2 - Φ1) is greater than the first threshold value TH1 Condition 2: (δ u2 - δ u1 ) + (δ d2 - δ d1 ) is greater than the third threshold value TH3

[0106] If condition 1 or condition 2 is satisfied, there is a high possibility that an offset angle exists in the pair of upper and lower rudders 4u and 4d. Therefore, when condition 1 or condition 2 is satisfied, the failure detection unit 17 determines that a failure has occurred in one of the pair of upper and lower rudders 4u and 4d, and outputs failure detection information (step ST411). In one embodiment, the failure detection unit 17 may determine that a failure has occurred in one of the pair of upper and lower rudders 4u and 4d when both condition 1 and condition 2 are satisfied. On the other hand, when condition 1 or condition 2 is not satisfied, it is determined that no failure has occurred in the pair of upper and lower rudders 4u and 4d, and a series of processes is terminated.

[0107] When the correction unit 18 receives the failure detection information, it calculates the offset angles Δδ u , Δδ d of the pair of upper and lower rudders 4u and 4d (step ST412). The offset angles Δδ u , Δδ d of the pair of upper and lower rudders 4u and 4d are calculated from the following formulas (11) and (12).

[0108] Δδ u = (B - A) / 2 …(11) Δδ d = (B + A) / 2 …(12)

[0109] In addition, A and B in Expressions (11) and (12) are defined as in the following Expressions (13) and (14). Therefore, the offset angle is calculated based on the roll angle Φ1, the roll angle Φ2, the roll angle Φ4, the rudder angles δ of the pair of upper and lower rudders 4u, 4d measured in the test environment u1 , δ d1 , the rudder angles δ of the pair of upper and lower rudders 4u, 4d measured in the operation environment u2 , δ d2 , and the angle δ b2 .

[0110] A = Δδ d -Δδ u = (Φ2 - Φ1) / Φ u …(13) B = Δδ d +Δδ u = -{(δ u2 - δ u1 ) + (δ d2 - δ d1 )} …(14)

[0111] Next, the correction unit 18 corrects the rudder angles of the pair of upper and lower rudders 4u, 4d based on the offset angles Δδ u , Δδ d (step ST413). For example, the correction unit 18 decreases the rudder angles of the pair of upper and lower rudders 4u, 4d by the offset angles Δδ u , Δδ d . That is, the corrected rudder angles δ u3 , δ d3 of the pair of upper and lower rudders 4u, 4d are expressed as in the following Expressions (15) and (16).

[0112] δ u3 = δ u2 - Δδ u …(15) δ d3 = δ d2 - Δδ d …(16)

[0113] As described above, in this method MT4, when (Φ2 - Φ1) is greater than the first threshold value TH1, or when (δ u2 - δ u1 ) + (δ d2 - δd1 ) is greater than the second threshold TH2, it is determined that a failure has occurred in one of the pair of upper and lower rudders 4u, 4d. Therefore, it is possible to detect that there is an offset angle in the pair of upper and lower rudders 4u, 4d. Also, based on the offset angles Δδ u , Δδ d By correcting the pair of upper and lower rudders 4u, 4d based on, the actual rudder angles of the pair of upper and lower rudders 4u, 4d can be made closer to the desired rudder angles. As a result, even when a failure occurs in the pair of upper and lower rudders 4u, 4d, it becomes possible to continue the operation of the underwater vehicle 1.

[0114] In the method MT4, when a failure of the rudder is detected by the failure detection unit 17, the rudder angles of the pair of upper and lower rudders 4u, 4d are corrected by the correction unit 18. However, in one embodiment, when a failure of the rudder is detected, the operation of the underwater vehicle 1 may be aborted without correcting the rudder angles of the pair of upper and lower rudders 4u, 4d, and the underwater vehicle 1 may be surfaced. In this case, the processes related to the correction of the rudder angles, specifically, steps ST404 to ST406, step ST412, and step ST413 may not be performed.

[0115] (Fifth Embodiment) Next, a method for detecting a failure of a rudder according to the fifth embodiment will be described. FIG. 7 is a flowchart showing a failure detection method MT5 according to the fifth embodiment. This method MT5 is a method for detecting that damage such as a chip has occurred in one of the rudder bodies 41 of the pair of left and right rudders 4l, 4r.

[0116] In the method MT5, first, a preparation step ST51 is performed. The preparation step ST51 is a step for acquiring the normal motion information of the underwater vehicle 1. The preparation step ST51 includes steps ST501 to ST506. Steps ST501 to ST506 are performed in a test environment where the normality of a plurality of rudders 4 is confirmed.

[0117] In the preparation step ST51, first, the underwater vehicle 1 is made to travel straight at a specific pitch angle in a test environment (step ST501). The specific pitch angle may be the pitch angle at which the underwater vehicle 1 dives, the pitch angle at which the underwater vehicle 1 travels horizontally, or the pitch angle at which the underwater vehicle 1 surfaces.

[0118] Next, the rudder angle acquisition unit 14 of the control device 10 acquires the rudder angles δ l1 , δ r1 of the pair of left and right rudders 4l and 4r of the underwater vehicle 1 traveling at a specific pitch angle (step ST502). The rudder angle acquisition unit 14 stores the acquired rudder angles δ l1 , δ r1 in the storage unit 15.

[0119] Next, with the underwater vehicle 1 traveling straight horizontally, the fault detection unit 17 temporarily increases the rudder angle of the left rudder 4l by Δδ e . For example, the fault detection unit 17 instantaneously increases the rudder angle of the left rudder 4l to δ l1 +Δδ e and then returns the rudder angle of the left rudder 4l to δ l1 . During this time, the rudder angle of the right rudder 4r is maintained at δ r1 . When the rudder angle of the left rudder 4l temporarily increases, a moment around the Y-axis is generated in the underwater vehicle 1. Next, the fault detection unit 17 measures the maximum pitch angle acceleration α l0 of the underwater vehicle 1 caused by the change in the rudder angle of the left rudder 4l (step ST504).

[0120] Next, with the underwater vehicle 1 traveling straight horizontally, the fault detection unit 17 temporarily increases the rudder angle of the right rudder 4r by Δδ e . For example, the fault detection unit 17 instantaneously increases the rudder angle of the right rudder 4r to δ r1 +Δδ e and then returns the rudder angle to δ r1 . During this time, the rudder angle of the left rudder 4l is δ l1It is maintained. When the rudder angle of the right rudder 4r temporarily increases, a moment around the Y-axis is generated in the underwater vehicle 1. Next, the failure detection unit 17 determines the maximum pitch angular acceleration α of the underwater vehicle 1 that occurs along with the change in the rudder angle of the right rudder 4r r0 and measures it (step ST506).

[0121] When the preparation step ST51 ends, the detection step ST52 is performed. The detection step ST52 detects a failure of the underwater vehicle 1 and corrects the rudder angles of the plurality of rudders 4 when a failure is detected. The detection step ST52 includes steps ST507 to ST515 described later. Steps ST507 to ST515 are performed in an operating environment where the normality of the plurality of rudders 4 has not been confirmed.

[0122] In the detection step ST52, first, the underwater vehicle 1 is made to travel straight at a specific pitch angle in the operating environment (step ST507). Next, the rudder angle acquisition unit 14 of the control device 10 determines the rudder angles δ of the pair of left and right rudders 4l, 4r of the underwater vehicle 1 traveling at a specific pitch angle l2 , δ r2 and acquires them (step ST508). The rudder angle acquisition unit 14 stores the acquired rudder angles δ l2 , δ r2 in the storage unit 15. At this time, in addition to the rudder angles δ of the pair of left and right rudders 4l, 4r l2 , δ r2 , the rudder angles δ of the pair of upper and lower rudders 4u, 4d u2 , δ d2 may be acquired.

[0123] Next, the failure detection unit 17 determines whether (δ l2 - δ l1 ) - (δ r2 - δ r1 ) is greater than the third threshold value TH3 (step ST509). (δ l2 - δ l1 ) - (δ r2 - δ r1If (δ l2 -δ l1 )-(δ r2 -δ r1 ) is greater than the third threshold TH3, there is a high possibility that damage such as a chip has occurred in one of the rudder bodies 41 of the pair of left and right rudders 4l and 4r, and the rudder body 41 cannot generate a rudder lift force corresponding to the rudder angle. Therefore, when (δ l2 -δ l1 )-(δ r2 -δ r1 ) is greater than the third threshold TH3, the failure detection unit 17 determines that a failure has occurred in one of the pair of left and right rudders 4l and 4r, and outputs failure detection information (step ST510). On the other hand, when (δ l2 -δ l1 )-(δ r2 -δ r1 ) is less than or equal to the third threshold TH3, it is determined that no failure has occurred in the pair of left and right rudders 4l and 4r, and a series of processes is terminated.

[0124] When the correction unit 18 detects a failure in the pair of left and right rudders 4l and 4r, the rudder angle of the left rudder 4l is temporarily increased by Δδ e (step ST511). Next, the failure detection unit 17 measures the maximum pitch angle acceleration α l1 of the underwater vehicle 1 generated along with the change in the rudder angle of the left rudder 4l (step ST512).

[0125] Next, the correction unit 18 temporarily increases the rudder angle of the right rudder 4r by Δδ e (step ST513). Next, the failure detection unit 17 measures the maximum pitch angle acceleration α r1 of the underwater vehicle 1 generated along with the change in the rudder angle of the right rudder 4r (step ST514).

[0126] Next, the correction unit 18 corrects the rudder angles of the pair of left and right rudders 4l and 4r based on the maximum pitch angle accelerations α l0 , α r0 measured in the test environment and the maximum pitch angle accelerations α l1 , α r1 measured in the operation environment. Let the rudder angles of the pair of left and right rudders 4l and 4r before correction be δ l2 , δ r2 , and the rudder angles after correction be δ lc , δ rcWhen it is assumed that, for example, the rudder forces of a pair of left and right rudders 4l and 4r are proportional to the rudder angles, the corrected rudder angles δ lc , δ rc are obtained according to the following formulas (17) and (18).

[0127] δ lc = δ l2 / k l …(17) δ rc = δ r2 / k r …(18)

[0128] Here, k l , k r in formulas (17) and (18) are defined as in formulas (19) and (20). k l = α l1 / α l0 …(19) k r = α r1 / α r0 …(20)

[0129] Note that the correction unit 18 may calculate the corrected rudder angles δ lc , δ rc according to the following formulas (21) and (22) instead of formulas (17) and (18).

[0130] δ lc = asin(2sin(δ l2 )·cos(δ l2 ) / k) / 2 …(21) δ rc = asin(2sin(δ r2 )·cos(δ r2 ) / k) / 2 …(22)

[0131] As described above, in this method MT5, (δ l2 - δ l1 )-(δ r2 - δ r1When [[ID=]] is greater than the third threshold value TH3, it is determined that a failure has occurred in one of the pair of left and right rudders 4l and 4r. Therefore, it is possible to detect that damage such as a chip has occurred in the pair of left and right rudders 4l and 4r. Also, the maximum pitch angle acceleration α l0 , α r0 measured in the test environment and the maximum pitch angle acceleration α l1 , α r1 measured in the operating environment, by correcting the pair of left and right rudders 4l and 4r, even when damage has occurred in the pair of left and right rudders 4l and 4r and the rudder lift has decreased, the rudder lift of the pair of left and right rudders 4l and 4r can be made close to the normal rudder lift. As a result, even when a failure occurs in the pair of left and right rudders 4l and 4r, it is possible to continue the operation of the underwater vehicle 1.

[0132] In the method MT5, when a rudder failure is detected by the failure detection unit 17, the rudder angles of the pair of left and right rudders 4l and 4r are corrected by the correction unit 18. However, in one embodiment, when a rudder failure is detected, the operation of the underwater vehicle 1 may be stopped without correcting the rudder angles of the pair of left and right rudders 4l and 4r, and the underwater vehicle 1 may be surfaced. In this case, the processes related to the correction of the rudder angle, specifically, steps ST503 to ST506 and steps ST511 to ST515 may not be performed.

[0133] (Sixth Embodiment) Next, a method for detecting a rudder failure according to the sixth embodiment will be described. FIG. 8 is a flowchart showing a failure detection method MT6 according to the sixth embodiment. This method MT6 detects that damage such as a chip has occurred in one of the pair of upper and lower rudders 4u and 4d.

[0134] In the method MT6, first, a preparation step ST61 is performed. The preparation step ST61 is a step for acquiring the normal motion information of the underwater vehicle 1. The preparation step ST61 includes steps ST601 to ST606. Steps ST601 to ST606 are performed in a test environment where the normality of a plurality of rudders 4 is confirmed.

[0135] In the preparation step ST61, first, the underwater vehicle 1 is made to travel straight at a specific yaw angle in a test environment (step ST601). The specific yaw angle may be the yaw angle at which the underwater vehicle 1 dives, the yaw angle at which the underwater vehicle 1 travels horizontally, or the yaw angle at which the underwater vehicle 1 surfaces.

[0136] Next, the rudder angle acquisition unit 14 of the control device 10 acquires the rudder angles δ u1 , δ d1 of the pair of upper and lower rudders 4u, 4d of the underwater vehicle 1 traveling at a specific yaw angle (step ST602). The rudder angle acquisition unit 14 stores the acquired rudder angles δ u1 , δ d1 in the storage unit 15.

[0137] Next, the failure detection unit 17 temporarily increases the rudder angle of the upper rudder 4u by Δδ e in a state where the underwater vehicle 1 is traveling straight horizontally (step ST603). For example, the failure detection unit 17 instantaneously increases the rudder angle of the upper rudder 4u to δ u1 +Δδ e and then returns the rudder angle of the upper rudder 4u to δ u1 . During that time, the rudder angle of the lower rudder 4d is maintained at δ d1 . When the rudder angle of the upper rudder 4u temporarily increases, a moment around the Z-axis is generated in the underwater vehicle 1. Next, the failure detection unit 17 measures the maximum yaw angular acceleration α u0 of the underwater vehicle 1 generated along with the change in the rudder angle of the upper rudder 4u (step ST604).

[0138] Next, the failure detection unit 17 temporarily increases the rudder angle of the lower rudder 4d by Δδ e in a state where the underwater vehicle 1 is traveling straight horizontally (step ST605). For example, the failure detection unit 17 instantaneously increases the rudder angle of the lower rudder 4d to δ d1 +Δδ e and then returns the rudder angle to δ d1 . During that time, the rudder angle of the upper rudder 4u is maintained at δ u1 . When the rudder angle of the lower rudder 4d temporarily increases, a moment around the Z-axis is generated in the underwater vehicle 1. Next, the failure detection unit 17 measures the maximum yaw angular acceleration αd0 Measure it (step ST606).

[0139] When the preparation step ST61 ends, the detection step ST62 is performed. The detection step ST62 detects a failure of the underwater vehicle 1 and corrects the rudder angles of the plurality of rudders 4 when a failure is detected. The detection step ST62 includes steps ST607 to ST615 described later. Steps ST607 to ST615 are performed in an operating environment where the normality of the plurality of rudders 4 has not been confirmed.

[0140] In the detection step ST62, first, the underwater vehicle 1 is made to travel straight at a specific yaw angle in the operating environment (step ST607). Next, the rudder angle acquisition unit 14 of the control device 10 acquires the rudder angles δ u2 , δ d2 of the upper and lower pair of rudders 4u, 4d of the underwater vehicle 1 traveling at a specific yaw angle (step ST608). The rudder angle acquisition unit 14 stores the acquired rudder angles δ u2 , δ d2 in the storage unit 15. At this time, in addition to the rudder angles δ u2 , δ d2 of the upper and lower pair of rudders 4u, 4d, the rudder angles δ u2 , δ d2 of the upper and lower pair of rudders 4u, 4d may be acquired.

[0141] Next, the failure detection unit 17 determines whether (δ u2 - δ u1 )-(δ d2 - δ d1 ) is greater than the third threshold value TH3 (step ST609). If (δ u2 - δ u1 )-(δ d2 - δ d1 ) is greater than the third threshold value TH3, there is a high possibility that damage such as a chip has occurred in one of the rudder bodies 41 of the upper and lower pair of rudders 4u, 4d, and the rudder body 41 cannot generate lift corresponding to the rudder angle. Therefore, the failure detection unit 17 determines that (δ u2 - δ u1 )-(δ d2 - δ d1) is greater than the third threshold TH3, it is determined that a failure has occurred in one of the pair of upper and lower rudders 4u, 4d, and failure detection information is output (step ST610). On the other hand, (δ u2 -δ u1 )-(δ d2 -δ d1 ) is less than or equal to the third threshold TH3, it is determined that no failure has occurred in the pair of upper and lower rudders 4u, 4d, and a series of processes is terminated.

[0142] When the correction unit 18 detects a failure in the pair of upper and lower rudders 4u, 4d, the rudder angle of the upper rudder 4u is temporarily increased by Δδ e (step ST611). Next, the failure detection unit 17 measures the maximum yaw angular acceleration α u1 of the underwater vehicle 1 that occurs along with the change in the rudder angle of the upper rudder 4u (step ST612).

[0143] Next, the correction unit 18 temporarily increases the rudder angle of the lower rudder 4d by Δδ e (step ST613). Next, the failure detection unit 17 measures the maximum yaw angular acceleration α d1 of the underwater vehicle 1 that occurs along with the change in the rudder angle of the lower rudder 4d (step ST614).

[0144] Next, the correction unit 18 corrects the rudder angles of the pair of upper and lower rudders 4u, 4d based on the maximum yaw angular accelerations α u0 , α d0 measured in the test environment and the maximum yaw angular accelerations α u1 , α d1 measured in the operation environment. When the rudder angles of the pair of upper and lower rudders 4u, 4d before correction are δ u2 , δ d2 and the rudder angles after correction are δ lc , δ rc , for example, assuming that the rudder forces of the pair of upper and lower rudders 4u, 4d are proportional to the rudder angles, the rudder angles δ uc , δ dc after correction are obtained according to the following formulas (23) and (24).

[0145] δ uc = δ u2 / k u…(23) δ dc = δ d2 / k d …(24)

[0146] k in Expressions (23) and (24) l , k r is defined as in Expressions (25) and (26). k u = α u1 / α u0 …(25) k d = α d1 / α d0 …(26)

[0147] Note that the correction unit 18 may calculate the corrected rudder angle δ lc , δ rc according to the following Expressions (27) and (28) instead of Expressions (23) and (24).

[0148] δ lc = asin(2sin(δ u2 )·cos(δ u2 ) / k) / 2 …(27) δ rc = asin(2sin(δ d2 )·cos(δ d2 ) / k) / 2 …(28)

[0149] As described above, in this method MT6, when (δ u2 - δ u1 )-(δ d2 - δ d1 ) is greater than the third threshold value TH3, it is determined that a failure has occurred in one of the pair of upper and lower rudders 4u, 4d. Therefore, it is possible to detect that damage such as chipping has occurred in the pair of upper and lower rudders 4u, 4d. Also, the maximum yaw angular acceleration α u0 , α d0 measured in the test environment and the maximum yaw angular acceleration α u1 , α d1Based on this, by correcting the pair of upper and lower rudders 4u and 4d, even when damage occurs to the pair of upper and lower rudders 4u and 4d and the rudder lift decreases, the rudder lift of the pair of upper and lower rudders 4u and 4d can be made close to the normal rudder lift. As a result, even when a failure occurs in the pair of upper and lower rudders 4u and 4d, it is possible to continue the operation of the underwater vehicle 1.

[0150] In the method MT6, when a rudder failure is detected by the failure detection unit 17, the rudder angles of the pair of upper and lower rudders 4u and 4d are corrected by the correction unit 18. However, in one embodiment, when a rudder failure is detected, the operation of the underwater vehicle 1 may be stopped without correcting the rudder angles of the pair of upper and lower rudders 4u and 4d, and the underwater vehicle 1 may be surfaced. In this case, the processes related to the correction of the rudder angles, specifically, steps ST603 to ST606 and steps ST611 to ST615, may not be performed.

[0151] As described above, the failure detection methods according to various embodiments have been described. However, the present invention is not limited to the above-described embodiments, and various modifications can be configured without changing the gist of the invention. For example, although the plurality of rudders 4 described above are cross rudders arranged above, below, left, and right of the underwater vehicle 1, in one embodiment, the plurality of rudders 4 may be X rudders arranged at an angle of 45° with respect to the up, down, left, and right directions of the underwater vehicle 1.

[0152] Note that the above-described various embodiments can be combined within a non-contradictory range. For example, the control device 10 of the underwater vehicle 1 may simultaneously execute the failure detection method MT1 according to the first embodiment and the failure detection method MT2 according to the second embodiment. For example, the control device 10 may execute the detection steps ST12 and ST22 after executing the preparation steps ST11 and ST21 in a test environment. Similarly, the control device 10 of the underwater vehicle 1 may simultaneously execute the failure detection method MT3 according to the third embodiment and the failure detection method MT4 according to the fourth embodiment. For example, the control device 10 may execute the detection steps ST32 and ST42 after executing the preparation steps ST31 and ST41 in a test environment. In this case, when (Φ2 - Φ1) is greater than the first threshold value, when (δ l2 -δ l1 )+(δ r2 -δ r1 ) is greater than the second threshold value, or when (δ u2 -δ u1 )+(δ d2 -δ d1 ) is greater than the third threshold value, the failure detection unit 17 of the control device 10 determines that a failure has occurred in one of the plurality of rudders 4.

Description of Reference Numerals

[0153] 1 Underwater vehicle 4 Plurality of rudders 4l, 4r Pair of left and right rudders 4u, 4d Pair of upper and lower rudders δ c1 , δ c2 Corrected rudder angle Δδ d , Δδ l , Δδ r , Δδ u Offset angle Φ1 Roll angle (first roll angle) Φ2 Roll angle (second roll angle) Φ3 Roll angle (third roll angle) Φ4 Roll angle (fourth roll angle) MT1, MT2, MT3, MT4, MT5, MT6 Failure detection methods

Claims

1. A fault detection method for detecting a fault in a rudder of an underwater vehicle having a plurality of rudders, comprising: a first step of measuring a roll angle of the underwater vehicle traveling at a specific pitch angle or a specific yaw angle in a test environment where the normality of the plurality of rudders has been confirmed; a second step of measuring a roll angle of the underwater vehicle traveling at the specific pitch angle or the specific yaw angle in an operating environment where the normality of the plurality of rudders has not been confirmed; a third step of detecting a fault in one of the plurality of rudders based on a difference between the roll angle of the underwater vehicle measured in the test environment and the roll angle of the underwater vehicle measured in the operating environment; wherein the plurality of rudders include a pair of left and right rudders for adjusting the pitch angle of the underwater vehicle and a pair of upper and lower rudders for adjusting the yaw angle of the underwater vehicle; in the first step, a first roll angle, which is the roll angle of the underwater vehicle traveling at the specific pitch angle in the test environment, is measured, and a second roll angle, which is the roll angle of the underwater vehicle traveling at the specific yaw angle in the test environment, is measured; in the second step, a third roll angle, which is the roll angle of the underwater vehicle traveling at the specific pitch angle in the operating environment, is measured, and a fourth roll angle, which is the roll angle of the underwater vehicle traveling at the specific yaw angle in the operating environment, is measured; in the third step, when the difference between the first roll angle and the third roll angle is greater than a first threshold value, it is determined that a fault has occurred in one of the pair of left and right rudders, and when the difference between the second roll angle and the fourth roll angle is greater than a second threshold value, it is determined that a fault has occurred in one of the pair of upper and lower rudders; a fault detection method.

2. Set the rudder angle of one of the pair of upper and lower rudders of the underwater vehicle to δ ａ１ and set the rudder angle of the other of the pair of upper and lower rudders to -δ ａ１ and a step of setting it; the rudder angle δ ａ１ changing it step by step by a certain angle, and the rudder angle δ ａ１ generating first correlation data indicating the relationship between the roll angle of the underwater vehicle and the rudder angle δ; a step of determining a corrected rudder angle of the pair of upper and lower rudders for reducing the difference between the first roll angle and the third roll angle using the first correlation data; a step of correcting the rudder angle of the pair of upper and lower rudders based on the determined corrected rudder angle of the pair of upper and lower rudders; Set the rudder angle of one of the pair of left and right rudders of the underwater vehicle to δ ａ２ and set the rudder angle of the other of the pair of left and right rudders to -δ ａ２ and a step of setting; the rudder angle δ ａ２ changing it step by step by a certain angle, the rudder angle δ ａ２ generating second correlation data indicating the relationship between the roll angle of the underwater vehicle a step of determining a corrected rudder angle of the pair of left and right rudders for reducing the difference between the second roll angle and the fourth roll angle using the second correlation data; a step of correcting the rudder angle of the pair of left and right rudders based on the determined corrected rudder angle of the pair of left and right rudders; The fault detection method according to claim 1, further comprising:

3. A fault detection method for detecting a fault in a rudder of an underwater vehicle having a plurality of rudders, comprising: In a test environment where the normality of the plurality of rudders has been confirmed, a first step of measuring the roll angle of the underwater vehicle traveling at a specific pitch angle or a specific yaw angle; In an operating environment where the normality of the plurality of rudders has not been confirmed, a second step of measuring the roll angle of the underwater vehicle traveling at the specific pitch angle or the specific yaw angle; A third step of detecting a failure of one of the plurality of rudders based on the difference between the roll angle of the underwater vehicle measured in the test environment and the roll angle of the underwater vehicle measured in the operating environment; including; The plurality of rudders include a pair of left and right rudders for adjusting the pitch angle of the underwater vehicle and a pair of upper and lower rudders for adjusting the yaw angle of the underwater vehicle; In the first step, in the test environment, the first roll angle Φ of the underwater vehicle traveling straight forward horizontally １ , the rudder angles δ ｌ１ , δ ｒ１ of the pair of left and right rudders, and the rudder angles δ ｕ１ , δ ｄ１ of the pair of upper and lower rudders are measured, In the second step, in the operation environment, the second roll angle Φ of the underwater vehicle traveling straight ahead horizontally ２ , the rudder angles δ ｌ２ , δ ｒ２ of the pair of left and right rudders, and the rudder angles δ ｕ２ , δ ｄ２ of the pair of upper and lower rudders are measured, In the third step, (Φ ２ - Φ １ ) is greater than the first threshold value, (δ ｌ２ - δ ｌ１ ) + (δ ｒ２ - δ ｒ１ ) is greater than the second threshold value, or (δ ｕ２ - δ ｕ１ ) + (δ ｄ２ - δ ｄ１ ) is greater than the third threshold value, it is determined that a failure has occurred in one of the plurality of rudders; A fault detection method.

4. In the test environment, the rudder angle of one of the pair of left and right rudders of the underwater vehicle traveling straight ahead horizontally is increased by an angle δ ｂ１ while the rudder angle of the other of the pair of left and right rudders is decreased by an angle δ ｂ１ and the third roll angle Φ which is the roll angle of the underwater vehicle at this time is measured ３ and a step of measuring; First roll angle Φ １ , second roll angle Φ ２ , third roll angle Φ ３ , the rudder angles δ ｌ１ , δ ｒ１ of the pair of left and right rudders measured in the test environment, the rudder angles δ ｌ２ , δ ｒ２ of the pair of left and right rudders measured in the operating environment, and based on the angle δ ｂ１ , a step of calculating an offset angle of the rudder angles of the pair of left and right rudders A step of correcting the rudder angles of the pair of left and right rudders based on the offset angles of the rudder angles of the pair of left and right rudders; In the test environment, the rudder angle of one of the pair of upper and lower rudders of the underwater vehicle traveling straight ahead horizontally is increased by an angle δ ｂ２ only, and the rudder angle of the other of the pair of upper and lower rudders is decreased by the angle δ ｂ２ when the roll angle of the underwater vehicle is the fourth roll angle Φ ４ measuring step; First roll angle Φ １ , second roll angle Φ ２ , fourth roll angle Φ ４ , the rudder angles δ ｕ１ , δ ｄ１ of the pair of upper and lower rudders measured in the test environment, ｕ２ , δ ｄ２ of the pair of upper and lower rudders measured in the operating environment, , and based on the angle δ ｂ２ , a step of calculating an offset angle of the rudder angles of the pair of upper and lower rudders; A step of correcting the rudder angles of the pair of upper and lower rudders based on the offset angles of the rudder angles of the pair of upper and lower rudders; The fault detection method according to claim 3, further including.

5. A fault detection device for detecting a fault of a rudder of an underwater vehicle having a plurality of rudders, An attitude information acquisition unit that acquires the roll angle of the underwater vehicle traveling at a specific pitch angle or a specific yaw angle in a test environment where the normality of the plurality of rudders has been confirmed, and in an operating environment where the normality of the plurality of rudders has not been confirmed, acquires the roll angle of the underwater vehicle traveling at the specific pitch angle or the specific yaw angle; A fault detection unit that detects a fault of one of the plurality of rudders based on the difference between the roll angle of the underwater vehicle acquired in the test environment and the roll angle of the underwater vehicle acquired in the operating environment; comprising; The plurality of rudders include a pair of left and right rudders for adjusting the pitch angle of the underwater vehicle and a pair of upper and lower rudders for adjusting the yaw angle of the underwater vehicle; The attitude information acquisition unit acquires a first roll angle that is the roll angle of the underwater vehicle traveling at the specific pitch angle in the test environment, and a second roll angle that is the roll angle of the underwater vehicle traveling at the specific yaw angle in the test environment, and also acquires a third roll angle that is the roll angle of the underwater vehicle traveling at the specific pitch angle in the operation environment, and a fourth roll angle that is the roll angle of the underwater vehicle traveling at the specific yaw angle in the operation environment. When the difference between the first roll angle and the third roll angle is greater than a first threshold value, the failure detection unit determines that a failure has occurred in one of the pair of left and right rudders, and when the difference between the second roll angle and the fourth roll angle is greater than a second threshold value, the failure detection unit determines that a failure has occurred in one of the pair of upper and lower rudders. Failure detection device.

6. A rudder angle control unit that controls the rudder angles of the plurality of rudders; A correction unit that corrects the rudder angles of the plurality of rudders; The failure detection device further includes: The rudder angle control unit sets the rudder angle of one of the pair of upper and lower rudders of the underwater vehicle to δ ａ１ and sets the rudder angle of the other of the pair of upper and lower rudders to -δ ａ１ and changes the rudder angle δ ａ１ by a fixed angle each time. The failure detection unit generates first correlation data indicating the relationship between the rudder angle δ ａ１ and the roll angle of the underwater vehicle, The correction unit uses the first correlation data to determine correction rudder angles of the pair of upper and lower rudders that reduce the difference between the first roll angle and the third roll angle, and corrects the rudder angles of the pair of upper and lower rudders based on the determined correction rudder angles of the pair of upper and lower rudders. The rudder angle control unit sets the rudder angle of one of the pair of left and right rudders of the underwater vehicle to δ ａ２ and sets the rudder angle of the other of the pair of left and right rudders to -δ ａ２ and changes the rudder angle δ ａ２ little by little at a constant angle. The failure detection unit generates second correlation data indicating the relationship between the rudder angle δ ａ２ and the roll angle of the underwater vehicle, The correction unit uses the second correlation data to determine correction rudder angles of the pair of left and right rudders that reduce the difference between the second roll angle and the fourth roll angle, and corrects the rudder angles of the pair of left and right rudders based on the determined correction rudder angles of the pair of left and right rudders. The failure detection device according to claim 5.

7. A failure detection device for detecting a failure of a rudder of an underwater vehicle having a plurality of rudders, An attitude information acquisition unit that acquires the roll angle of the underwater vehicle traveling at a specific pitch angle or a specific yaw angle in a test environment where the normality of the plurality of rudders has been confirmed, and also acquires the roll angle of the underwater vehicle traveling at the specific pitch angle or the specific yaw angle in an operation environment where the normality of the plurality of rudders has not been confirmed; A failure detection unit that detects a failure of one of the plurality of rudders based on the difference between the roll angle of the underwater vehicle acquired in the test environment and the roll angle of the underwater vehicle acquired in the operation environment; The failure detection device includes: The plurality of rudders include a pair of left and right rudders that adjust the pitch angle of the underwater vehicle and a pair of upper and lower rudders that adjust the yaw angle of the underwater vehicle. The posture information acquisition unit acquires the first roll angle Φ of the underwater vehicle traveling straight ahead horizontally in the test environment １ , the rudder angles δ ｌ１ , δ ｒ１ of the pair of left and right rudders, and the rudder angles δ ｕ１ , δ ｄ１ of the pair of upper and lower rudders, and acquires the second roll angle Φ of the underwater vehicle traveling straight ahead horizontally in the operation environment ２ , the rudder angles δ ｌ２ , δ ｒ２ of the pair of left and right rudders, and the rudder angles δ ｕ２ , δ ｄ２ of the pair of upper and lower rudders, and The failure detection unit (Φ ２ - Φ １ ) is greater than the first threshold value, (δ ｌ２ - δ ｌ１ ) + (δ ｒ２ - δ ｒ１ ) is greater than the second threshold value, or, (δ ｕ２ - δ ｕ１ ) + (δ ｄ２ - δ ｄ１ ) is greater than the third threshold value, Determine that a failure has occurred in one of the plurality of rudders Failure detection device

8. Further comprising a correction unit for correcting the rudder angles of the plurality of rudders The posture information acquisition unit acquires, in the test environment, the roll angle Φ ３ of the underwater vehicle when the rudder angle of one of the pair of left and right rudders of the underwater vehicle traveling straight ahead horizontally is increased by an angle δ ｂ１ and the rudder angle of the other of the pair of left and right rudders is decreased by an angle δ ｂ１ . ｂ１ by increasing the rudder angle of one of the pair of left and right rudders of the underwater vehicle by an angle δ ｂ１ and decreasing the rudder angle of the other of the pair of left and right rudders by an angle δ ｂ１ , ｂ１ and obtaining the third roll angle Φ ３ which is the roll angle of the underwater vehicle when the rudder angle of one of the pair of left and right rudders of the underwater vehicle traveling straight ahead horizontally is increased by an angle δ ｂ１ and the rudder angle of the other of the pair of left and right rudders is decreased by an angle δ ｂ１ . ３ ​ The failure detection unit includes the first roll angle Φ １ , the second roll angle Φ ２ , the third roll angle Φ ３ , the rudder angles δ ｌ１ , δ ｒ１ of the pair of left and right rudders measured in the test environment, the rudder angles δ ｌ２ , δ ｒ２ of the pair of left and right rudders measured in the operation environment, and based on the angle δ ｂ１ , calculates the offset angle of the rudder angles of the pair of left and right rudders. The correction unit corrects the rudder angles of the pair of left and right rudders based on the offset angles of the rudder angles of the pair of left and right rudders The posture information acquisition unit acquires, in the test environment, the roll angle Φ ４ (the fourth roll angle) of the underwater vehicle when the rudder angle of one of the pair of upper and lower rudders of the underwater vehicle traveling straight forward horizontally is increased by an angle δ ｂ２ and the rudder angle of the other of the pair of upper and lower rudders is decreased by the angle δ ｂ２ . ｂ２ while increasing the rudder angle of one of the pair of upper and lower rudders by an angle δ ｂ２ ｂ２ and decreasing the rudder angle of the other of the pair of upper and lower rudders by the angle δ ｂ２ ４ and acquires the roll angle Φ ４ (the fourth roll angle) of the underwater vehicle. The failure detection unit is the first roll angle Φ １ , the second roll angle Φ ２ , the fourth roll angle Φ ４ , the rudder angles δ ｕ１ , δ ｄ１ of the pair of upper and lower rudders measured in the test environment, the rudder angles δ ｕ２ , δ ｄ２ of the pair of upper and lower rudders measured in the operation environment, and based on the angle δ ｂ２ , calculates the offset angle of the rudder angles of the pair of upper and lower rudders, The correction unit corrects the rudder angles of the pair of upper and lower rudders based on the offset angles of the rudder angles of the pair of upper and lower rudders. The failure detection device according to claim 7

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