Method for calculating water height and associated device.

Abstract

A calculation method, implemented in a vessel (100) comprising a bathymetric sounder (120), characterized in that it comprises the following first steps: Receiving a first geographical location (p0) of the vessel (100), Receiving an actual water depth (prr0) at the first location (p0) from the bathymetric sounder (120), Determining at least a second geographical location (L10, L4, L7), comprising at least a second water depth measurement in a nautical chart (111') from the first location (p0), Determining a chart water depth at the first location (prc0) from said at least a second water depth measurement, Estimating a water height (h0) at the first location, from the actual water depth at the first location (prr0) minus the chart water depth at the first location (prc0). Figure for the summary: Figure 1

Description

Title of the invention: Method for calculating water height and associated device.

[0001] The invention relates to the navigation of a ship.

[0002] A nautical chart, used for navigation, includes water depth measurements, relative to a hydrographic zero, at a plurality of geographical locations.

[0003] To know the actual water depth, it is necessary to add a height of water, above the hydrographic zero, to the water depth measurements of the nautical chart.

[0004] In a conventional way, the water height is estimated by the tide determined from tables or calculations.

[0005] The water level is estimated in reference ports. However, this water level loses its accuracy as one moves away from said reference ports.

[0006] The water height is indeed influenced by other parameters, having a local character, such as barometric pressure, ocean currents, the rise in water level caused by global warming which can vary locally, and possibly, waves.

[0007] There is now a need to improve the accuracy of the calculation of water height relative to hydrographic zero.

[0008] To this end, the invention relates to a calculation method, implemented in a vessel comprising a bathymetric sounder, for example by an electronic device located in or on the vessel, characterized in that it comprises the following first steps: - Receiving a first geographical location of the vessel on (or in) a body of water, - Receiving an actual water depth at the first location from the bathymetric sounder (and the process may include a step of measuring the actual depth by the bathymetric sounder), - Determination of at least one second geographical location, including at least one second water depth measurement (i.e., a sounding) (relative to a hydrographic zero) on a nautical (bathymetric) chart (electronic or digital) from the first location, then - Reading said at least a second depth measurement in the nautical chart (at said at least a second location), then - Determination of a cartographic water depth at the first location based on at least one second water depth measurement, Then - Estimation of a water height at the first location, based on the actual water depth at the first location minus the mapped water depth at the first location.

[0009] Thus the invention makes it possible to estimate the height of water at the location of the boat in a direct, reliable and rapid manner.

[0010] The locations (first, second and / or third below in particular) according to the invention include for example a latitude and a longitude.

[0011] For example, the first steps can be repeated, for example: - With a frequency between 0.1 hertz and 10 Hertz, and / or - While the ship is moving,

[0012] To take into account possible waves, the water height is the smallest estimated, during the repetition of the first steps, for a predetermined duration of, for example, between twenty seconds and one minute.

[0013] A wave profile, for example, wave frequency and amplitude (in the body of water), can be determined from the evolution, during the repetition of the first steps, of the difference between the actual water depth at the first location and the mapped water depth at the first location. The water height can also be obtained from this wave profile.

[0014] It is thus possible to determine a water height when the ship is in a trough of a wave.

[0015] According to one embodiment, the first geographic location is received from a satellite geolocation module of the ship, for example of the so-called "GPS" type. Alternatively, the first geographic location is obtained from radar data, bathymetric data, or detection of the ship's movements by an inertial navigation system on the ship.

[0016] The bathymetric sounder is for example an acoustic or laser sounder or of another type.

[0017] According to one embodiment, the ship includes a draft.

[0018] For example, the body of water includes a bottom and a surface.

[0019] A true depth can be a distance (in a vertical direction relative to the Earth's horizon), between the surface and the bottom, or between the bottom and the bathymetric sounder located for example at a distance from the surface equal to the draft.

[0020] The water height at the first location can be the actual water depth at the first location minus the charted water depth at the first location. Alternatively, the water height can be the actual water depth at the first location plus the draft minus the charted water depth at the first location.

[0021] According to one embodiment, in a conventional manner, the nautical chart includes a water depth measurement (for example, a chart sounding or a point on an isobath), relative to a hydrographic zero, at each of the locations of a plurality of geographical locations.

[0022] For example, the plurality of geographical locations includes said at least one second location.

[0023] The nautical chart can be stored in the electronic device's memory. Alternatively, it can be read from a server remote from the ship (via a satellite network, for example).

[0024] According to one embodiment, said at least one second geographical location comprises several (for example three, or less than ten or twenty) second geographical locations.

[0025] Said at least one second geographical location consists, for example, of three, or less than ten or twenty geographical locations.

[0026] According to one embodiment, the cartographic water depth at the first location is an interpolation of said several second geographical locations.

[0027] In other words, according to one embodiment: - Said at least one second water depth measurement includes several second water depth measurements, and / or - The cartographic water depth at the first location is an interpolation of said several second water depth measurements.

[0028] Alternatively, the mapped water depth at the first location is a minimum among several second depth measurements.

[0029] According to another variant, said at least one second geographical location comprises a single geographical location (for example, equal to said first geographical location) and said at least one second depth measurement comprises a single depth measurement. In this case, the charted water depth at the first location may be this single depth measurement.

[0030] According to one embodiment, the method further includes a step of determining a triangulation of the plurality of geographical locations.

[0031] According to one embodiment, the triangulation comprising a first triangle in which the first location is situated (and the process may include a step of determining this triangle), the first triangle comprising first three vertices, at first three geographical locations, comprising first three water depth measurements, said at least a second location being constituted by the first three locations.

[0032] Alternatively, said at least a second location consists of the four locations, among the plurality of geographical locations, closest to the first location.

[0033] According to one embodiment, the triangulation is a triangulation such that none of the locations of the plurality of locations is (strictly) inside the circumcircle of one of the triangles of the triangulation. Such a triangulation is called a "Delaunay triangulation".

[0034] Alternatively, the triangulation can be, for example, a constrained triangulation, a so-called "Steiner" triangulation or a segment triangulation.

[0035] According to one embodiment, the cartographic water depth at the first location is an average of the first three water depth measurements weighted by barycentric coordinates of the first location with respect to the first triangle (in other words; with respect to the first three vertices).

[0036] Alternatively, the map water depth at the first location is a median or a minimum of the first three water depth measurements.

[0037] According to one embodiment, the process further comprises the following second steps: - Determination of a third geographical location (different from the first and second locations) (located, for example, at a distance of between 1 meter and 10 kilometers from the first location) then - Determination of at least a fourth geographical location, including at least a fourth water depth measurement (in other words: a sounding), on the nautical chart, starting from the third location, then - Reading said at least a fourth depth measurement in the nautical chart (at said at least a fourth location), then - Determination of a cartographic water depth at the third location from said at least a fourth water depth measurement, then - Estimation of the actual water depth at the third location from the sum of the water height and the mapped water depth at the third location.

[0038] Alternatively, the water height can be transmitted to other ships or to land for other uses, for example to estimate a risk of submersion.

[0039] The third location is for example determined from the first location (for example, the third location is chosen so as to be at a distance less than a threshold from the first location).

[0040] According to one embodiment, the method according to the invention further comprises a step of determining a trajectory of the ship, the third location being on the trajectory of the ship.

[0041] For example, the trajectory may have a length and the length of the trajectory may be determined from a predetermined safety time or safety distance.

[0042] According to one embodiment, the method includes a step of determining a safety zone, the third location being within the safety zone. For example, the safety zone is a semicircle (centered on the vessel) whose base is orthogonal to a direction of movement of the vessel. The radius of the semicircle may be equal to the length of the trajectory.

[0043] Alternatively, the electronic device includes a display screen, and the method according to the invention includes a step of displaying the water depth measurement (optionally, at certain locations) of each of the geographical locations of the plurality of geographical locations added to the water height.

[0044] Thus, according to this variant, thanks to the invention, during the navigation of the ship, it is possible to visualize an estimate of the actual depth around the ship on a screen.

[0045] According to one embodiment, the ship's trajectory includes areas of the body of water where at least a portion of the ship will be present during a planned movement of the ship,

[0046] The trajectory can, for example, be determined from a direction and a speed of movement of the ship.

[0047] For example, the second steps are repeated for, at each repetition, a third different location situated in the trajectory at a different position from a plurality of positions uniformly distributed in the trajectory, for example far from the ship or from each other according to a predetermined step.

[0048] For example, the trajectory may measure at least between 50 meters and 2 kilometers. In other words, the planned displacement of the vessel is between 50 meters and 2 kilometers.

[0049] The trajectory can be, for example, a curve or a straight line.

[0050] The actual water depth at the third location can be the sum of the water height and the chart water depth at the third location. Alternatively, the actual water depth at the third location can be the sum of the water height and the chart water depth at the third location, less the draft (and possibly less one foot from the pilot).

[0051] For example, the plurality of geographical locations includes said at least a fourth location.

[0052] According to one embodiment, said at least one fourth geographical location comprises several fourth geographical locations.

[0053] According to one embodiment, the mapped water depth at the third location lisation is an interpolation of said several fourth geographical locations.

[0054] In other words, according to one embodiment: - Said at least one fourth water depth measurement includes several fourth water depth measurements, and / or - The cartographic water depth at the third location is an interpolation of said several fourth water depth measurements.

[0055] Alternatively, the chart water depth at the third location is a minimum among several fourth depth measurements.

[0056] Alternatively, said at least a fourth geographical location comprises a single geographical location (for example, equal to said third geographical location) and said at least a fourth depth measurement comprises a single water depth measurement. In this case, the charted water depth at the third location may be this single water depth measurement.

[0057] According to one embodiment, the triangulation includes a third triangle in which the third location is situated (and the process may include a step of determining this triangle), the third triangle comprising three third vertices at three third geographical locations comprising three third water depth measurements, said at least a fourth location, being constituted by the three third locations.

[0058] Alternatively, said at least fourth location consists of the four locations, of the plurality of geographical locations, closest to the third location.

[0059] According to one embodiment, the cartographic water depth at the third location is the average of the three third water depth measurements weighted by barycentric coordinates of the third location with respect to the third triangle (in other words; with respect to the three third vertices).

[0060] Alternatively, the map water depth at the first location is a median or a minimum of the three third water depth measurements.

[0061] According to one embodiment, the second steps comprise the following steps: - Comparison of the actual water depth at the third location with a predetermined threshold, - Command to restore an alarm, for example audible or in the form of a vibration of a connected watch by wireless communication to the electronic device, (in the ship) if the actual water depth at the third location is less than the predetermined threshold.

[0062] For example, the predetermined threshold may be equal to the draft plus possibly one foot of the pilot (which is a safety margin).

[0063] The alarm can be modulated (its intensity can be modulated if the alarm is a sound, for example) depending on the proximity of the third location to the ship.

[0064] The alarm can be modulated (its intensity can be modulated if the alarm is a sound, for example) depending on whether the third location is in the trajectory or in the safety zone outside the trajectory.

[0065] The alarm display can, for example, also be implemented on a screen, such as a screen of the electronic device, or the screen of a watch connected by wireless communication to the electronic device.

[0066] When the ship's satellite geolocation module is out of service (the satellite signal is lost, for example) or when the bathymetric sounder is out of service or when the first location or when the third location is outside the area represented by the map, the method may include a step of emitting a first warning message (for example, different from the alert message).

[0067] When the water level is above (and / or below) a threshold, the method may include a step of emitting a second warning message (for example, different from the alert message, and / or the first warning message). The data obtained are then considered inconsistent.

[0068] The invention also relates to a computer program comprising instructions, executable by a microprocessor or a microcontroller or a computer, to implement the steps of the process according to the invention, when executed by the microprocessor or the microcontroller or the computer.

[0069] The method according to the invention can be implemented by an electronic device (or by a ship).

[0070] The invention therefore also relates to an electronic device (or a vessel) configured to implement the steps of the process according to the invention.

[0071] The invention also relates to a vessel comprising the electronic device.

[0072] The characteristics and advantages of the vessel and the electronic device are identical to those of the method according to the invention (without it being necessary to repeat them here).

[0073] An electronic device, vessel, or other element is understood to be "configured to" (or "suitable to") perform or implement a step or operation by the fact that the element includes means for (in other words, "designed to" or "adapted to") performing the step or operation. These are preferably electronic means, for example, a computer program, data in memory, specialized electronic circuits, wired or wireless connections, a microprocessor, and / or a microcontroller. They may also be micromechanical or mechanical means.

[0074] When a step or operation is carried out (in other words: implemented) by such an element, this generally implies that the element includes means to carry out the step or operation.

[0075] Other features and advantages of the present invention will become more apparent from the following detailed description, which includes embodiments of the invention given by way of non-limiting examples and illustrated by the accompanying drawings, in which.

[0076] [Fig-1] represents an electronic device and a ship, according to a mode of rea Description of the invention, top view.

[0077] [Fig.2] represents the electronic device and the ship [Fig.1], in side view.

[0078] [Fig.3] represents an implementation of the process according to the invention, according to a first example of implementation, by the electronic device and the ship of figures 1.

[0079] In Figures 1 and 2, certain elements are, of course, seen through transparency. The ship's sails (not referenced), and the loudspeaker 140, shown in [Fig. 2], are not shown in [Fig. 1] to facilitate understanding of [Fig. 1].

[0080] Detailed description of an example embodiment of the invention.

[0081] With reference to figures 1 to 3. At step S00, a sailing vessel 100 sails on a body of water 200 comprising a bottom 220 and a surface 210.

[0082] . Ship 100 includes, for example, a satellite geolocation module 130 of the ship 100, for example of the so-called "GPS" type and a bathymetric sounder 120, for example an acoustic sounder, connected to the electronic device 110 (which may have the architecture of a computer or a microprocessor, and the electronic device may store a computer program comprising instructions, executable by the electronic device, to implement the steps of the process according to the invention, when executed by the electronic device).

[0083] Figures 1 and 2 also show, superimposed with the vessel 100 and its surroundings, a nautical chart 111' stored in the memory 111 of the electronic device 110. The nautical chart 111' includes a water depth measurement, in this case, a chart sounding, relative to a hydrographic zero, at each of the locations L10, L4, L7, L0, L1, and L2 as below: - Depth measurement at location L10: 10 meters, - Depth measurement at location L4: 4 meters, - Depth measurement at location L7: 7 meters, - Depth measurement at location L0: 0 meters, - Depth measurement at location Ll: 1 meter - Depth measurement at location L2: 2 meters.

[0084] At step S10, device 110 receives the geographic location pO of ship 100 from satellite geolocation module 130.

[0085] In step S20, the device 110 receives from the bathymetric sounder an actual water depth prrO measured by the bathymetric sounder 120 at location pO. The bathymetric sounder 120 first determines the distance between the sounder 120 and the bottom 220, here 6 meters, and adds a constant, equal to the draft, here equal to 4 meters, to determine the distance between the surface 210 and the bottom 220 at location pO. Thus, the actual water depth prrO is 10 meters at location pO.

[0086] At step S30, the device 110 determines a triangulation of the locations L10, L4, L7, L0, L1, and L2, which includes the triangles T1, T2, T3, T4 and T5, for example, by implementing the algorithm described in the article: - “Rex A. Dwyer. A faster divide-and-conquer algorithm for constructing delaunay triangulations, Algorithmica volume 2, pages l37-151 (1987) »

[0087] At step S40, device 110 determines that, since the location pO is inside triangle Tl, it is therefore the locations L10, L4, L7 of map 111' which are relevant for the location pO.

[0088] At step S50, the device 110 reads, in memory 111, the depths at locations L10, L4, L7 of the map 111'.

[0089] At step S60, the device 110 determines, from the depths at locations L10, L4, L7, a cartographic water depth prcO, at location pO, equal to 7 meters. For example, the cartographic water depth prcO is an average of the water depth measurements at locations L10, L4, L7 weighted by the barycentric coordinates of pO (namely 1 / 3, 1 / 3, 1 / 3) with respect to the first triangle Tl (thus we have: prcO = (10+4+7) / 3= 7).

[0090] At step S70, device 110 calculates the water height hO equal to prrO -prcO, here equal to 3 meters (10 meters - 7 meters = 3 meters).

[0091] For example, steps S10 to S70 can be repeated with a frequency of 5 Hertz.

[0092] To take into account possible waves, the water height hO retained is the smallest estimated during these repetitions over 30 seconds of navigation.

[0093] At step S80, the vessel 110 is sailing in a straight line at very low speed (for example 1 knot).

[0094] At step S90, the device 110 determines the trajectory trajO of the vessel with a length ml equal to 13.5 meters from a direction and speed of movement of the vessel. The length ml represents a safety time or safety distance.

[0095] At step SI 10, the device 110 determines a location p3 situated on the trajectory trajO.

[0096] At step S120, the device 110 determines that, since location p3 is inside triangle T3, it is therefore locations L0, L1, L2 of map 111' which are per- tinentes pour la locale p3.

[0097] At step S130, the device 110 reads, in memory 111, the depths at locations LO, L1, L2 of the map 111'.

[0098] At step S140, the device 110 determines, from the depths at locations L0, L1, L2, a chart water depth prc3 at location p3 equal to 1 meter. For example, the chart water depth prc3 at position p3 is an average of the water depth measurements at locations L0, L1, L2 weighted by the barycentric coordinates of p3 (namely 1 / 3, 1 / 3, 1 / 3) with respect to the first triangle T3 (thus: prc3 = (0+2+1) / 3= 1). In the example given here, chosen for its simplicity, triangle T3 is equilateral and p3 is the centroid of T3, but other configurations are of course also possible.

[0099] At step S150, device 110 estimates an actual water depth prr3 at the third location p3 equal to hO + prc3 = 3 + 1=4 meters.

[0100] The draft tirO of the vessel 100 is, for example, 4 meters. A pilot foot ppO of 1 meter is provided to constitute a safety margin.

[0101] At step S160, device 110 compares the actual water depth prr3 at the third location p3 to the draft tirO plus the pilot's foot ppO. Since the actual water depth prr3 at the third location p3 is less than the draft tirO plus the pilot's foot ppO (4 < 4 + 1), device 110 commands an alarm to be sounded in the vessel 100 via a loudspeaker 140.

[0102] The method may also include a step of determining the safety zone zsl, and the third location may be within the safety zone. The safety zone is a semicircle zsl whose base is orthogonal to a direction of movement dl of the vessel. The radius of the semicircle may be equal to the length ml of the trajectory trajO.

[0103] The intensity of the alarm can be reduced modulated when the third location is in the safety zone zsl outside the trajectory trajO.

[0104] Step SI 10 is preceded by step S100, which is implemented after step S90. In step S100, device 110 determines actual water depths of 10 meters at location pl and 6 meters at location p2. Since these depths are greater than the draft tirO plus the pilot's foot ppO, no alarm is triggered. Step S100 is implemented in the same way as steps SI 10 to S160, except that location pl, being located at location L7, is equal to the depth measurement at location L7.

[0105] The locations p0, pl1, p2, and p3 are distributed homogeneously in the middle of the trajectory, but they can be distributed in different ways. In the example given here, the actual water depth is calculated once in each triangle along the trajectory, but the water depth can be calculated at less frequent locations. distant (or further apart) from each other, for example depending on the reception frequency of the satellite geolocation module 130.

Claims

Claims

1. Calculation method, implemented in a ship (100) comprising a bathymetric sounder (120), characterized in that it comprises the following first steps: - Reception (S 10) of a first geographical location (pO) of the ship (100), - Reception (S20) of an actual water depth (prrO) at the first location (pO) from the bathymetric sounder (120), - Determination (S40) of at least one second geographical location (L10, L4, L7), comprising at least one second water depth measurement in a nautical chart (111') from the first location (pO), - Reading (S50) of said at least one second depth measurement in the nautical chart (111'), - Determination (S60) of a cartographic water depth at the first location (prcO) from said at least one second water depth measurement.- Estimation (S70) of a water height (hO) at the first location, from the actual water depth at the first location (prrO) minus the mapped water depth at the first location (prcO).

2. Calculation method according to the preceding claim in which said at least one second geographical location (L10, L4, L7) comprises several second geographical locations, and in which the cartographic water depth at the first location (prcO) is an interpolation of said several second geographical locations.

3. A calculation method according to any one of the preceding claims, the nautical chart (111') comprising a water depth measurement at each of a plurality of geographic locations (L10, L4, L7, L0, L1, L2), the method further comprising a step of determining (S30) a triangulation of the plurality of geographic locations (L10, L4, L7, L0, L1, L2).

4. Calculation method according to the preceding claim in which the trian- regulation comprising a first triangle (Tl) in which the first location (pO) is located, the first triangle (Tl) comprising three first vertices, at three first geographical locations, comprising three first water depth measurements, said at least one second location (L10, L4, L7) being constituted by the three first locations.

5. Calculation method according to any one of the preceding claims further comprising the following second steps: - Determining (S 10) a third geographical location (p3), - Determining (S 120) at least one fourth geographical location (LO, L1, L2), comprising at least one fourth water depth measurement, in the nautical chart (111'), from the third location (p3), - Reading (S 130) said at least one fourth depth measurement in the nautical chart (111'), - Determining (S 140) a cartographic water depth at the third location (prc3) from said at least one fourth water depth measurement. - Estimating (S 150) an actual water depth at the third location (prr3) from the sum of the water height (hO) and the cartographic water depth at the third location (prc3).

6. Calculation method according to the preceding claim further comprising a step of determining (S90) a trajectory of the ship (trajO), the third location (p3) being on the trajectory of the ship (trajO).

7. A calculation method according to claim 5 or 6 wherein said at least one fourth geographic location (L0, L1, L2) comprises several fourth geographic locations, and wherein the mapped water depth at the third location (prc3) is an interpolation of said several fourth geographic locations.

8. Computer program comprising instructions, executable by a microprocessor or a microcontroller, for implementing the steps of the method according to any one of claims 1 to 7, when executed by the microprocessor or microcontroller.

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