Ship systems

Abstract

The present invention provides a ship system capable of preventing damage caused by false GNSS signals from affecting surrounding vessels when the vessel itself receives such signals. [Solution] The ship system is characterized in that the ship 2 is equipped with a positioning unit 212 of a GNSS compass 21 that measures the ship's position based on GNSS signals transmitted from multiple satellites, and an anomaly detection unit 211 of the GNSS compass 21 that detects anomalies in the GNSS signals, and the ship 2 transmits ship information, including the ship's position measured by the positioning unit 212 of the GNSS compass 21, to other ships 2A, and if an anomaly is detected by the anomaly detection unit 211 of the GNSS compass 21, it disables the transmission of ship information to other ships 2A, or suggests to the user that it be disabled.

Description

Technical Field

[0004] , , , , , , ,

[0001] This invention relates to a ship system for reducing damage caused by false GNSS (Global Navigation Satellite System) signals.

Background Art

[0002] An electronic chart information display device (ECDIS: Electronic Chart Display and Information System) mounted on a ship displays geographical information from a nautical electronic chart on a screen and integrates various information from a radar, an automatic identification system (AIS), a depth finder, and a NAVigational TEleX (NAVigational TEleX) that mainly receives weather information and displays it on the screen. In addition, by having a function of outputting an alert when the own ship approaches another ship or approaches a shoal or a quay wall (for example, see Patent Document 1), the safety of navigation is enhanced.

[0003] <00000​​​​​​​​​​​​ Japanese Patent Publication No. 2015-164006 [Patent Document 2] Patent No. 4803862 [Patent Document 3] Japanese Patent Publication No. 2023-155130 [Patent Document 4] Special Publication No. 2024-515652 [Overview of the Initiative] [Problems that the invention aims to solve]

[0005] Incidentally, if a GNSS receiver on a certain vessel X receives a false GNSS signal and calculates an incorrect position from that false GNSS signal, the AIS on vessel X will adopt the incorrect position calculated from that false GNSS signal as the vessel's position and transmit it to other vessels as its own position information. Furthermore, the ECDIS on vessel X will display that incorrect position information on its screen or output a false collision warning based on that incorrect position information, thus hindering safe navigation. For this reason, as automation of ships through manpower reduction and remote control from land progresses, there is a need to develop a system that can mitigate the damage caused by false GNSS signals.

[0006] Therefore, the present invention aims to provide a ship system that can prevent damage caused by false GNSS signals from affecting surrounding ships when a ship is receiving false GNSS signals. [Means for solving the problem]

[0007] To solve the above problems, the invention described in claim 1 is a ship system comprising: position measuring means for measuring the position of the ship based on GNSS signals transmitted from a plurality of satellites; and anomaly detection means for detecting anomalies in the GNSS signals, wherein the ship transmits ship information, including the position of the ship measured by the position measuring means, to other ships, and if an anomaly is detected by the anomaly detection means, it disables the transmission of the ship information to other ships or proposes to the user that it be disabled.

[0008] The invention described in claim 2 is a ship system as described in claim 1, wherein the ship is equipped with a position information utilization calculation means that performs calculations using the position of the ship measured by the position measurement means, and when an anomaly is detected by the anomaly detection means, the position information utilization calculation means invalidates the position of the ship measured by the position measurement means, or proposes to the user that it be invalidated. [Effects of the Invention]

[0009] According to the invention of claim 1, if a ship detects an anomaly in its GNSS signal, it can disable the transmission of its own ship information, including its position measured based on a false GNSS signal, to other ships. This prevents damage caused by the false GNSS signal from affecting surrounding ships and improves navigational safety.

[0010] According to the invention of claim 2, if a ship detects an anomaly in the GNSS signal, the position information utilization calculation means, which performs calculations using the ship's position, is configured to invalidate the ship's incorrect position measured based on a false GNSS signal (and suggests this to the user). This makes it possible to more reliably prevent damage caused by false GNSS signals from affecting surrounding ships and improve navigational safety. [Brief explanation of the drawing]

[0011] [Figure 1] This is a block diagram showing the schematic configuration of a ship system according to an embodiment. [Figure 2]Figure 1 is a block diagram showing the schematic configuration of a GNSS compass. [Figure 3] Figure 1 is a flowchart showing the operation of the ship's system. [Figure 4] Figure 1 is a schematic diagram illustrating the positional relationship between ships (our ship and other ships) as displayed in the ECDIS. [Modes for carrying out the invention]

[0012] The present invention will be described below based on the illustrated embodiments.

[0013] Figure 1 is a block diagram showing the schematic configuration of a ship system 1 according to an embodiment of the present invention. The ship system 1 according to this embodiment mainly comprises a ship (own ship) 2 and another ship 2A. Here, the ship (own ship) 2 and the other ship 2A are connected in a way that allows communication via AIS, which will be described later.

[0014] Ship (own ship) 2 is mainly equipped with a GNSS compass (position measurement means, anomaly detection means) 21, AIS 22, control unit 23, and ECDIS (position information utilization calculation means) 24, while other ship 2A is mainly equipped with an AIS 22A. Other ship 2A may also be equipped with a GNSS compass, control unit, and ECDIS. Here, the AIS 22 of ship (own ship) 2 and the AIS 22A of other ship 2A are connected in a way that allows communication via international VHF (VHF radio waves), as will be described later. It should be assumed that the AIS 22 and AIS 22A have the same function and configuration.

[0015] Figure 2 is a block diagram showing the schematic configuration of the GNSS compass 21 in Figure 1.

[0016] The GNSS compass 21 installed on the ship (own ship) 2 is equipped with functions to receive satellite signals / positioning signals (referred to as "GNSS signals") transmitted from each of a plurality of satellites used in GNSS (referred to as "GNSS satellites") and detect abnormalities in the GNSS signals that are received signals in GNSS, and to calculate the position of the own ship, etc. It mainly has a control unit, a GNSS antenna 213, a GNSS receiver 214, an abnormality detection unit (abnormality detection means) 211, and a positioning unit (position measurement means) 212. Each part constituting the GNSS compass 21 is connected so that signals can be transmitted and received via a bus and information can be communicated with each other.

[0017] Examples of GNSS include GPS (abbreviation for Global Positioning System, Global Positioning Satellite; Global Positioning System), GLONASS (abbreviation for GLObal Navigation Satellite System), Galileo, and BDS (abbreviation for BeiDou navigation satellite System; Beidou Satellite Navigation System).

[0018] Each of the plurality of GNSS satellites transmits, as radio waves, GNSS signals including ephemeris, which is data indicating the current position of the GNSS satellite itself. The GNSS signals transmitted from each of the plurality of GNSS satellites also include information indicating the time when the GNSS satellite transmitted the GNSS signal as radio waves.

[0019] The control unit is equipped with a function to control the operations of each part constituting the GNSS compass 21, and is configured as a device having a central processing unit (CPU: abbreviation for Central Processing Unit) that performs arithmetic processing involved in, for example, detecting abnormalities in GNSS signals and calculating the position of the GNSS compass 21, etc.

[0020] The control unit also serves as a storage area for storing programs, various types of information, and data that the central processing unit (CPU) uses when performing arithmetic operations involved in detecting abnormalities in GNSS signals and calculating the position of the GNSS compass 21, etc., or as a working area for temporarily storing data, information, etc. generated when the central processing unit (CPU) performs the above arithmetic operations. For example, it is configured as a device having at least one of a read-only memory device ROM (abbreviation for Read Only Memory), a read-write memory device RAM (abbreviation for Random Access Memory), and a hard disk.

[0021] The control unit controls the start, content, and end of the processing of each part constituting the GNSS compass 21 according to a control program by causing the central processing unit (CPU) to execute a program (referred to as the "control program") for controlling the operation of the GNSS compass 21.

[0022] The GNSS receiving unit 214 is a device for receiving GNSS signals transmitted from a plurality of GNSS satellites S_i (where i is a unique number for each satellite for distinguishing the plurality of GNSS satellites from each other), and is composed of at least two GNSS receivers each having a GNSS antenna 213. In this embodiment, the GNSS receiving unit 214 is composed of three GNSS receivers 214X, 214Y, and 214Z, the GNSS receiver 214X has a GNSS antenna 213X, the GNSS receiver 214Y has a GNSS antenna 213Y, and the GNSS receiver 214Z has a GNSS antenna 213Z.

[0023] Each of the GNSS receivers 214X, 214Y, and 214Z receives the GNSS signals transmitted from each of the GNSS satellites S_i via the GNSS antennas 213X, 213Y, and 213Z, converts them into electrical signals (particularly, digital signals), and outputs them.

[0024] The GNSS signal is superimposed on a carrier wave and transmitted sequentially from the GNSS satellite S_i as radio waves (referred to as "GNSS radio waves"). Each GNSS receiver 214X, 214Y, and 214Z receives the GNSS radio waves, demodulates them, and extracts the GNSS signal. The GNSS signal is then output from the GNSS receiver unit 214.

[0025] The anomaly detection unit 211 is a device for detecting anomalies in the GNSS signal output from the GNSS receiving unit 214 and outputting the detection result. In this embodiment, it detects anomalies in the GNSS signal on the ship (the ship itself).

[0026] The method for detecting anomalies in the received signal in the anomaly detection unit 211 is not particularly limited, but may include, for example, a method of receiving GNSS signals transmitted from multiple GNSS satellites S_i via multiple GNSS antennas 213X, 213Y, and 213Z and determining whether the transmission time of the GNSS signal is normal based on a comparison of the transmission time of the GNSS signal contained in the GNSS signal with a predetermined reference transmission time (detection of transmission time anomaly); a method of determining whether the pseudo-distance ρ_i of the GNSS satellite S_i is normal based on a comparison of the pseudo-distance ρ_i of the GNSS satellite S_i that transmitted the GNSS signal with the pseudo-distance ρr of a predetermined reference satellite Sr (detection of pseudo-distance anomaly); or a method of determining whether the direction of arrival of the GNSS signal is normal based on an index representing the difference in paths from the GNSS satellite S_i that transmitted the GNSS signal to each of the multiple GNSS antennas 213X, 213Y, and 213Z (detection of path difference anomaly). Details of each of the above detection methods are described in Japanese Patent Application Publication No. 2023-155130 (Patent Document 3) by the present applicant.

[0027] The positioning unit 212 is a device for calculating and outputting positioning information based on the GNSS signal output from the GNSS receiving unit 214, and in this embodiment, it measures the position of the vessel (own ship). The positioning information calculated by the positioning unit 212 includes, for example, the ship's position, bearing, and attitude (e.g., rolling, pitching, rotation rate (ROT)). The calculation process of positioning information by the positioning unit 212 can be performed using well-known techniques, and this invention is not limited to specific items or methods, so a detailed explanation is omitted.

[0028] Here, if the positioning unit 212 uses a GNSS signal (false GNSS signal) transmitted from a GNSS satellite S_i that is classified as abnormal for the calculation of positioning information, it is predicted that the position of the ship (own ship) output from the positioning unit 212 will indicate an incorrect position.

[0029] The AIS (Automatic Identification System) 22 and 22A are devices that use international VHF (VHF radio waves) to automatically identify the movements of ships. Their basic configuration is the same as existing AIS systems that are required to be installed on ships that meet certain standards under the SOLAS Convention (International Convention for the Safety of Life at Sea).

[0030] The AIS22 of vessel 2 is connected to the AIS22A of other vessel 2A via international VHF (VHF radio waves), and transmits its own ship information (specifically, information such as the ship's identification number (MMSI number), ship name, position, course, speed, and destination; hereinafter also referred to as "AIS information") to the AIS22A. The position information included in the AIS information of vessel 2 is the position of the ship measured by the positioning unit 212 of the GNSS compass 21. In other words, vessel 2 transmits its own ship information (AIS information), including the position of the ship measured by the positioning unit 212 of the GNSS compass 21, to other vessel 2A via the AIS22 and AIS22A. Therefore, if vessel 2 receives a false GNSS signal, the position of the ship included in the own ship information (AIS information) is expected to be incorrect. Therefore, if the anomaly detection unit 211 detects an anomaly in the GNSS signal, the vessel (own ship) 2 will disable the transmission of its own ship information (AIS information), including its position measured by the positioning unit 212 of the GNSS compass 21, to the other ship 2A (and will suggest this to the user). Specifically, for example, the vessel (own ship) 2 will either not transmit its own ship information (AIS information) to the other ship 2A via AIS 22, or will transmit its own ship's position as "not positioned".

[0031] The control unit 23 is a device that primarily has the function of controlling the GNSS compass 21, AIS 22, and ECDIS 24.

[0032] The ECDIS (Electronic Chart Display and Information System) 24 is a device that integrates geographical information from nautical electronic charts, positional information such as the ship's position, bearing, and speed, and information from various devices installed on the ship, and displays it on a screen. It also has a function to output a warning when the ship approaches another ship or approaches a shoal or quay. Its basic configuration is the same as existing ECDIS systems that are required to be installed on ships that meet certain standards under the SOLAS Convention.

[0033] The ECDIS24 used in this embodiment is a device that performs calculations using the position of the ship (own ship) 2, and mainly comprises a display unit 241 and an alarm output unit 242.

[0034] The display unit 241 is a device for displaying various information, specifically, as shown in Figure 4, it displays the position of the vessel (own ship) 2 and the position of the other ship 2A. Here, the position of the vessel (own ship) 2 is the position measured by the positioning unit 212 of the GNSS compass 21. The position of the other ship 2A is the position obtained from AIS 22A, and if the other ship 2A is equipped with a GNSS compass, it may be the position measured by its positioning unit.

[0035] In other words, the display unit 241 of the ECDIS24 displays the position of the vessel (own ship) 2 measured by the positioning unit 212 of the GNSS compass 21 on the screen. Therefore, if the positioning unit 212 of the GNSS compass 21 calculates the position of the vessel (own ship) 2 based on a false GNSS signal, the display unit 241 of the ECDIS24 will display the incorrect position of the vessel (own ship) 2 ("AIS position of vessel (own ship) 2 (incorrect)" in Figure 4). For this reason, if the anomaly detection unit 211 of the vessel (own ship) 2 detects an anomaly in the GNSS signal, the vessel (own ship) 2 will suggest to the user that the position of the vessel measured by the positioning unit 212 of the GNSS compass 21 be invalidated on the display unit 241, that is, it will suggest to the user that it not be displayed on the display unit 241. In this case, the vessel (own ship) 2 may also suggest to the user that all vessel information (AIS information), including the position of the vessel, not be displayed on the display unit 241.

[0036] The alarm output unit 242 is a device for outputting an alarm to warn of the risk of collision with a ship or other vessel. Specifically, it determines whether there is a risk of collision between the two ships based on the position of the ship (own ship) 2 and the position of the other ship 2A, and outputs an alarm. Here, the position of the ship (own ship) 2 is the position measured by the positioning unit 212 of the GNSS compass 21. The position of the other ship 2A is the position of the other ship 2A obtained by AIS 22 from AIS 22A, and if the other ship 2A is equipped with a GNSS compass, it may be the position measured by its positioning unit.

[0037] In other words, the ECDIS24 alarm output unit 242 outputs an alarm using the position of the vessel (own ship) 2 measured by the positioning unit 212 of the GNSS compass 21. Therefore, if the positioning unit 212 of the GNSS compass 21 calculates the position of the vessel (own ship) 2 based on a false GNSS signal, the determination of whether or not there is a risk of collision between the two ships will be made based on the incorrect position of the vessel (own ship) 2. As a result, there is a risk of issuing a false alarm by determining that a collision will occur even though the two ships are not actually approaching each other (and therefore there is no need to avoid it) (see Figure 4). For this reason, if the abnormality detection unit 211 detects an abnormality in the GNSS signal, the vessel (own ship) 2 proposes to invalidate the position of the vessel measured by the positioning unit 212 of the GNSS compass 21 in the alarm output determination process of the alarm output unit 242, that is, it proposes not to use it in the collision prediction calculation. In this case, the vessel (own ship) 2 may choose not to use any of its own ship information (AIS information), including its own position, in the collision prediction calculation at the alarm output unit 242 (and may suggest this to the user).

[0038] The alarm output by the alarm output unit 242 may be displayed on the display unit 241 as a message or code, or it may be output as a sound such as a buzzer.

[0039] Next, the operation and function of the ship system 1 of this embodiment will be explained based on Figure 3.

[0040] First, the anomaly detection unit 211 of the GNSS compass 21 installed on the ship (our ship) 2 detects an anomaly in the GNSS signal (step S1).

[0041] Meanwhile, the vessel (own ship) 2 measures its own position using the positioning unit 212 of the GNSS compass 21 (step S2). The position of the vessel (own ship) 2 measured here is based on the GNSS signal in which an anomaly was detected, so it is expected to show an incorrect position.

[0042] Therefore, the AIS22 of ship 2 (own ship) disables the transmission of its own ship information (AIS information), including the incorrect position of the ship measured by the positioning unit 212 of the GNSS compass 21, to other ships 2A (and proposes this to the user). Specifically, "disabling transmission" means either setting the ship's position included in the own ship information (AIS information) to "not positioned" and then transmitting the ship information (AIS information) to other ships 2A (AIS22A) via international VHF (VHF radio waves) (step S3), or not transmitting the ship information (AIS information) to other ships 2A. This allows ship 2 (own ship) to prevent damage caused by false GNSS signals from affecting other ships.

[0043] Furthermore, the vessel (own ship) 2 proposes to the user to invalidate the incorrect position of the vessel measured by the positioning unit 212 of the GNSS compass 21 in the ECDIS 24 (step S4). Specifically, "invalidate" means not displaying the incorrect position of the vessel on the display unit 241 of the ECDIS 24, and not using the incorrect position of the vessel when the alarm output unit 242 determines the risk of collision between the vessel (own ship) 2 and another vessel 2A. This makes it possible to more reliably prevent damage to other vessels caused by false GNSS signals. In addition, the vessel (own ship) 2 may also invalidate (not display or not use) all other vessel information (AIS information) (speed, heading, etc.) obtained from AIS 22 in the ECDIS 24, not just its own position.

[0044] Ship (own ship) 2 may resume using its own ship information (AIS information), including its own position in ECDIS 24, when the anomaly detection unit 211 no longer detects anomalies in the GNSS signal.

[0045] As explained above, according to the ship system 1 of this embodiment, when a ship (own ship) 2 detects an anomaly in the GNSS signal, it will disable the transmission of its own ship information (AIS information), including its position measured based on a false GNSS signal, to other ships 2A (by suggesting this to the user). This prevents damage caused by false GNSS signals from affecting surrounding ships and improves navigational safety.

[0046] Furthermore, if the vessel (own ship) 2 detects an anomaly in the GNSS signal, the display unit 241 and alarm output unit 242 of the ECDIS 24, which performs calculations using the ship's position, are configured not to display or use (or to suggest to the user) the ship's incorrect position measured based on a false GNSS signal. This makes it possible to more reliably prevent damage caused by false GNSS signals from affecting surrounding vessels and improve navigational safety.

[0047] Although embodiments of this invention have been described above, the specific configuration is not limited to the embodiments described above, and any design changes, etc., that do not depart from the gist of this invention are also included. For example, in the above embodiments, the positioning unit and anomaly detection unit of a GNSS compass are given as examples of the position measurement means and anomaly detection means, but the position measurement means and anomaly detection means are not limited to the positioning unit and anomaly detection unit of a GNSS compass, and for example, a GNSS / inertial navigation system described in Patent Document 2 (Japanese Patent No. 4803862) by the present applicant may be used. Also, in the above embodiments, ECDIS is given as an example of the position information utilization calculation means, but any other system that performs calculations using the position of the ship measured based on the GNSS signal may be used. Furthermore, in the above embodiments, it is assumed that there is one other ship 2A, but there may be two or more ships. [Explanation of symbols]

[0048] 1. Ship Systems 2 Ship (own ship) 2A Other ship 21 GNSS compass (position measurement means, anomaly detection means) 211 Anomaly detection unit (anomaly detection means) 212 Positioning unit (position measurement means) 213 GNSS antenna 214 GNSS receiver 22,22A AIS 23 Control Unit 24 ECDIS (location information calculation means) 241 Display unit (calculation means using position information) 242 Alarm output unit (calculation means using position information)

Claims

1. The vessel is equipped with a position measurement means for measuring the ship's position based on GNSS signals transmitted from multiple satellites, and an anomaly detection means for detecting anomalies in the GNSS signals. The aforementioned vessel transmits its own ship information, including its position measured by the position measurement means, to other vessels, and if an anomaly is detected by the anomaly detection means, it disables the transmission of the aforementioned ship information to other vessels, or suggests to the user that it be disabled. A ship system characterized by the following features.

2. The aforementioned vessel is equipped with a position information utilization calculation means that performs calculations using the position of the vessel measured by the position measurement means, If an anomaly is detected by the anomaly detection means, the position information utilization calculation means will invalidate the position of the vessel measured by the position measurement means, or will suggest to the user that it be invalidated. The ship system according to claim 1.

Images