WO2010117278A1

WO2010117278A1 - Improved integrated marine search system

Info

Publication number: WO2010117278A1
Application number: PCT/NO2009/000139
Authority: WO
Inventors: Håkon SKJELTEN; Jonas Aamodt MORÆUS; Lars André SOLBERG
Original assignee: Aptomar As
Priority date: 2009-04-08
Filing date: 2009-04-08
Publication date: 2010-10-14
Also published as: AU2009344227B2; EP2417596A1; AU2009344227A1

Abstract

The invention relates to a marine recovery system comprising the following features: - a chart plotter (1) - a position sensor (10) arranged for displaying the vessel's (2) position (2N, 2E) in said chart plotter (1); - a position receiver (21) for other vessels' (22₁, 22₂,...) or objects (24) position (23N, 23E) and possibly their identity, and for displaying them in said chart section (4); - an pointing camera unit (3) for directing a stabilized main axis (31) towards a target (5) in or by the sea, and arranged for calculating the target's position (5N, 5E), - a camera image (45) for being displayed in said chart plotter (1) with an aiming circle (55) representing said stabilized main axis (31), and for moving said camera image (45) to a new desired position (53N, 53E) in said chart section (4); - an identification unit (7) connected to the pointing unit (3) arranged to select and assign to said target (5) a class (51) and for storing said assigned class (51) and said target's (5) position (53N, 53E) as an object (24) with a stored position (58N, 58E) in a second memory (82) for display as symbols (22s) in said chart plotter (1).

Description

improved integrated marine search system

The present invention relates to a marine search and recovery system with a nautical chart plotter arranged for displaying a vessel and its heading in a selected part of a nautical chart, and also for displaying other vessels or objects.

Background art and related problems

During marine operations, electronic naval chart plotters are usually used for displaying a naval chart on a screen, in true or relative course projection. The vessel usually also has a position calculating unit such as a global positioning system (GPS) sending signals to the chart plotter so as for enabling the chart plotter unit to compute an appropriate section of the chart in a scale, the scale usually selected by the operator.. It is further common usage to display the vessel itself generally centrally in the consecutively projected chart section as a boat-shaped symbol with the vessel's course track and heading indicated. Most civilian vessels above a given tonnage are furnished with an automatic identification system (AIS) broadcasting the vessel's position as furnished by the position calculating unit (usually the GPS) and an identification signal. Such broadcasted AlS-information from other vessels, when received by an AlS-receiver may also be forwarded to the chart plotter and display such civilian vessels as symbols in their relevant positions on the chart plotter.

The applicants have in European patent application EP06783992 disclosed a stabilized searchlight which is connected to acceleration sensors and arranged for keeping the light cone fixed on an object in an arbitrarily selected position at the sea surface. During the stabilizing process the object's position is calculated based on the vessel's own position, the relative direction and calculated relative position of the object. Then the object is registered. This may be useful from a safety-at-sea point of view so as for ensuring that a found object is not lost out of sight and, if possibly, reported to other vessels that may take over handling the object whether they have a correspondingly working searchlight or not.

However, it is desirable to have more than one local searchlight on one single vessel.

A searchlight may provide much information as such but there is a strong need for collecting such information in a way that enables acquisition and mutual distribution to several participating parts in a marine search operation, such as in routinely conducted operations as search for instrument buoys, mooring devices, flotsam or oil slicks, but also for more critical search and rescue operations for finding a vessel, a life raft or lifeboat, and not the least a search for one or more men overboard. In such situations it is highly desirable that all available vessels being capable of constructively contributing to the rescue operation arrive at the search area as soon as possible and that they are efficiently conducted. It is common practice to conduct visual observation and radar search, but it is not widespread practice to share information in other ways than by oral communication via radio. The applicants are at the time of filing not aware of systems that may meet the demand for coordinating the information exchange during search operations and for distributing the information in a way that may contribute to facilitate the coordination of localizing objects in the sea, or for finding a missing object in the sea in a coordinated and expedite way.

Large objects such as marine vessels and petroleum platforms usually provide radar identification signals or broadcast their AIS signals and are easily identified in radar images or chart plotters and provide no particular challenge to be found. The problem is rather the objects smaller than commercial vessels, such as drifting items such as containers, or pollution such as oil slicks, persons over board, all of which are not intended nor foreseen to go over board, but are subject to search operations when they do, they do of course not carry any marine identification.

The problem of a search operation leader is to collect and organize all available information provided by the searching vessels about the missing objects, and make good decisions about which ship to search where.

A general problem related to marine surveillance cameras or telescopes is that the operator may see objects, but he may not instantly know the observation direction or the geographical positions of the objects observed in the camera.

Another problem related to marine surveillance cameras is that the operator may be looking for objects in the camera image which are already indicated in a chart plotter, but he may not have the visual aid to correlate the two.

Short summary of the invention

The present invention contributes to a solution to the above-mentioned problem. The invention is a marine search system comprising the following features:

- a chart plotter for displaying a desired section of a chart from a chart representation in a first memory; - a vessel position sensor arranged for transmitting the vessel's position to the chart plotter said chart plotter being arranged for projecting a symbol for the vessel's position and heading in said chart section; - a position receiver arranged for receiving other vessels' or objects' position and possibly their identifications, of which the chart plotter is arranged for projecting symbols for said vessels or objects in said chart section. Further features of the search system according to the invention comprise: - a pointing unit arranged for directing a stabilized main axis towards a target in the vicinity of the vessel and arranged for calculating said target's position and being provided with a memory for storing said position;

- said pointing unit comprising one or more cameras arranged for transmitting a camera image for being displayed on said chart plotter with an aiming circle representing said main axis,

- said camera being stabilized so as for compensating for roll motion about said stabilized main axis so as for forming said camera image non-rotating on said chart plotter,

- wherein said chart plotter is arranged for displaying a camera chart pointer symbol in the position representing said main axis' intersection with the surface, and a camera command device for moving said camera chart pointer symbol to a new desired position in the chart section and thus command the steering of said main axis towards said new desired position,

- in which said chart plotter's camera image is arranged for displaying an image pointer symbol for a camera image steering device, in which a change of the position of said image pointer symbol contributes to commanding the rotation of said main axis towards a new position for main axis' intersection with the surface;

- an identification unit connected to said pointing unit arranged for on the basis of said camera image to select and assign to said target a class, and further for storing said target's class and position as a stored position in a second memory for display with symbols in said chart plotter.

Advantages of embodiments of the invention

One embodiment of the invention has an advantage in that it may classify an object as observed in the camera image on the chart plotter, calculate the classified object's position and selectably display a symbol representing the classified object in the so calculated position in the map on the chart plotter. The operator will thus have a correspondence between identified objects as seen in the camera image on the chart plotter and identified objects as seen in the chart plotter's map display. This will allow the camera image observer in his searching process to disregard already found and identified items and concentrate his attention to objects seen but not marked as identified. This is a significant advantage particularly if several men overboard and / or objects may be observed simultaneously and the observer shall search, find and classify them and provide the observed persons and objects' position to other participating vessels in a coordinated rescue operation.

In an advantageous embodiment of the invention the classified object's position is broadcasted as a virtual AIS so as for enabling all vessels having an AlS-receiver may plot the classified object in their maps regardless of having a chart plotter according to the invention.

In a further embodiment of the invention, the classified object may advantageously be displayed by a corresponding symbol overlain on the camera image on the chart plotter. The observed objects classified and / or identified may be stored in the memory controlled by chart plotter software of the invention which may further command the classified objects listed on the chart plotter or another screen.

The software listing may comprise touch-screen toggle symbols for selection of whether an object shall be displayed in the chart plotter or not, or overlaid in the camera image or not. The toggle switch symbols may be displayed in the list of objects so as for the operator to select which classified objects' symbols should be displayed. The central processing unit may then, based on the position of the vessel and the relative orientation of the camera axis, and camera image parameters, be able to continuously calculate which portions of the geographical area rendered in the map is correspondingly rendered in the camera image, and plot the symbols of objects appearing within the image, visible or not. This feature will in an advantageous way aid the operator in discriminating between newly found objects, and objects already found and identified, either by the operator on the present chart plotter or by other operators on other vessels' corresponding chart plotters, or by other observers having provided information which is registered in the system and broadcasted.

An advantage of an embodiment the invention is the feature of the stabilized axis and further anti roll corrected observation camera displaying a camera image with a stable horizon relative to the chart plotter display. A further advantage of the anti roll corrected camera image, which usually is rectangular, is the fact that the corresponding mapped trapezoids on the chart plotter will be stable and provide a less disturbed image and further provide a better defined series of trapezoids for storing which areas have been searched, and which areas that remain to be searched. Short figure captions

Fig. 1 illustrates a marine recovery system according to the invention with a chart plotter further arranged for displaying a camera image provided from a camera in a pointing unit on the vessel, in which the camera may be controlled by means of a camera control device being logically connected to the chart plotter, and in which the camera also may be controlled using an image pointer system in the image, and where observed objects such as vessels, persons and flotsam may be assigned to a class and displayed as a function of their positions in the chart plot and in the camera image.

Fig. 2 illustrates observed or calculated deviation of identified freely drifting objects. Further is illustrated an assumed deviatory motion of searched, trapezoidal-shaped areas which have been searched by using the camera.

Fig. 3 illustrates that the system according to the invention retrieves information about registered objects without their own AIS transmitter from the system's memory, and emits this information as emulated AIS signals via the vessel's own AIS transmitter, so as for the registered objects apparently to emit AIS signals informing about their own position and assigned identification.

Fig. 4 illustrates the effect and problem of the search vessel's combined roll and pitch motion on the axially stabilized camera image when displayed on a chart plotter resulting in a virtually inversely rolling image.

Description embodiments of the invention

The invention may thus broadly be described as comprising a marine recovery system comprising a map plotter further arranged for displaying a camera image (45) given by a camera arranged in a pointing unit (3) on the vessel. A deck unit of the background art marketed as "Securus" by the applicant may comprise the camera. The pointing unit (3) may in a preferred embodiment further comprise a searchlight (54). The camera (52) may be an ordinary video camera, an infrared video camera, or possibly an amplified night vision camera. The pointing unit (3) which is employed in the present invention is arranged for providing direction parameters for calculating the target's (5) position (5N, 5E) based on the vessel's position (2N₁ 2E) and heading (2A) and position (roll, pitch, yaw) in the water. The camera (52) is in the system arranged for being controlled in two ways: in a first mode it is arranged for being controlled using a camera command device (57) logically connected to the chart plotter (1). The camera (52) is in a second mode arranged for being controlled using an image pointer symbol in the image. Observed objects such as vessels, persons and flotsam may be assigned to a class and displayed by their positions in the chart plot (1) and in the camera image (45). The classification may take place visually using the camera (52) or automatically by image recognition, or by other information such as AIS information in conjunction with the camera axis position. The chart plotter (1) may also in the usual way be arranged to project a radar image across the map section such as shown in Fig. 1.

The camera (52) is in an embodiment arranged such that the camera image (45) is continuously stored in the second memory (82) such that it may, if desired, be retrieved for later display, e.g. as a documentation in a maritime court of inquiry, or if one later in a recovery operation should doubt the veracity of the observations at a given point in time or at a given position.

In additional detail, the marine search system according to the invention comprises the following features: A chart plotter (1) arranged in the usual manner for displaying a desired chart section (4) from a chart representation (6) in a first memory (8). A position sensor (10), e.g. a GPS, arranged on the vessel (2) arranged for calculating the position (2N, 2E) of the vessel (2) and for sending the position to the chart plotter (1). The chart plotter (1) is arranged in an ordinary manner to project at least one symbol (2s) representing the vessel's position (2N, 2E) and preferably the vessel's heading (2A) in the chart section (4). The position sensor (10) may be a GPS or an integrating so-called motion reference unit (MRU) or an inertial motion unit (IMU). Most vessels above a certain tonnage are equipped with a transmitter for its own position and identification of the vessel. The most common among such system is a so- called automatic identification system, abbreviated AIS, but some radars may also be arranged for coding the vessel's own identification into its own emitted radar signal. Also buoys and other objects may be provided with AIS. The system according to the invention is provided with a position receiver (21) arranged for receiving such other vessels' (22_{1 t} 22₂, ...) or such objects (24) positions (23N, 23E) and possible identity, whereas the chart plotter (1) according to the invention is arranged for projecting symbols (22s) for vessels or objects (22, 24) in the chart section (4). The search system according to the invention further comprises a series of features which are useful during recovery operations. A pointing unit (3), preferably mounted on deck, is arranged for directing a stabilized main axis (31) towards a target (5) in the or by the sea, and arranged for calculating the target's position (5N, 5E). A second memory (82) is arranged for calculating the target's (5) position. The pointing unit (3) comprises one or more cameras (52) arranged for transmitting a camera image (45) for display in the chart plotter (1). The cameras may function in continuous or discontinuous mode according to need. An aiming circle (55) in the camera image (45) represents the stabilized main axis (31) of the camera (52). The camera (52) may be controlled in at least two ways. The chart plotter (1) is arranged for displaying a camera chart pointer symbol (56) in a position (5N, 5E) which represents the intersection of said stabilized main axis (31) with the sea or land surface. The ordinary chart plane portion of the chart plotter (1) is provided with a camera command device (57), e.g. a so-called "mouse" pointer arranged for, either directly in the screen of the chart plotter (1) or in an indirect mode, moving the camera chart pointer symbol (56) to a new desired position (53N, 53E) in the chart section (4) and thus cause the stabilized main axis (31) of the camera (52) to be steered towards the new desired position (53N, 53E). With that, the camera (52) will be rotated to display a new camera image (45) having the new desired position (53N, 53E) in the center of the image (45). In an equivalent manner camera image (45) of the chart plotter (1) is arranged for displaying an image pointer symbol for a camera image control device (59). The camera command device (57) and the camera image control device (59) may in practice be comprised in one and the same command device (57, 59) which may be part of the same pointer system or "mouse pointer". A change in the image pointer symbol position results in a rotation of the stabilized main axis (31) towards a new desired position (53N", 53E¹) for the main axis' intersection with the sea or land surface. In this way the operator will experience that he or she may steer the camera image (45) using symbols in the displayed image itself.

It has been noticed by search test operators that it is inconvenient and strenuous to watch the camera image (45) on the chart plotter (1) if the vessel rolls and pitches in rough sea, the horizon in the camera image (45) makes an apparently counter roll motion relative to the rectangular frame of the chart plotter. This situation is illustrated in Fig. 4, in which the image is shown in two rotated positions, and in which corresponding trapezoids (parts of trapezoids) are illustrated as rotated to two rolled positions about the trajectory (31') corresponding to the camera axis (31) directed at the observed vessel (22). This image roll motion is due to a combined roll and pitch motion of the vessel relative to the horizon, and depends on the angle of the stabilized camera axis relative to the long axis of the ship. While the uncompensated image roll motion is tiresome to the observer it further requires manual correction from the observer for marking objects in the image using the pointer device when using an identification unit (7) in a manual mode as described below. In a preferred embodiment, the camera is anti roll stabilized so as for compensating for roll motion about the stabilized main axis so as for forming said camera image non-rotating on said chart plotter. An image roll compensated view is shown in Fig. 1. This may be achieved in two ways, either by providing an anti-roll compensation motor (60) to rotate the camera, or by anti-roll rotating the image obtained by a non-mechanically rolling camera. The camera (52) may in one preferred embodiment be arranged also rotatable about its lens¹ already stabilized axis (31). The camera (52) is mounted in a base unit which is usually arranged on a deck and which is stationary relative to the longitudinal and transverse axes of the vessel. Based on the running measurement of the actual roll and pitch position of the vessel and the azimuthal direction of the stabilized camera axis (31) relative to the long axis of the ship, a small motor (60) may be connected to counter-rotate the camera about its axis based on control signals calculated on the basis of the vessel's roll and pitch. If the stabilized axis (31) is directed parallel with the long axis of the rolling and pitching vessel, the camera must be image roll compensated about the stabilized axis by the negative of the roll angle, if the stabilized axis is directed parallel to the transverse axis of the rolling and pitching vessel, the camera must be image roll compensated about the stabilized axis by the negative of the pitch angle. For any intermediate direction of the stabilized axis relative to the longitudinal axis of the vessel, the image roll compensation angle must be a relative direction sine- and cosine corrected sum of the vessel's pitch and roll. This image roll compensation further prevents the chart plotter trapezoids corresponding to the camera image to rotate due to the vessel's roll and pitch, thus providing a steady, generally less disturbed chart plot, as illustrated in Fig. 1.

The camera image (45) in the display screen may also be provided with pointer devices arranged for commanding the camera lens¹ focal length (zooming) or light sensitivity, focus, frequency sensitivity, etc., or for selecting another camera, e.g. an infrared camera. An important component in the recovery system according to the invention is an identification unit (7) connected to the pointing unit (3) which is arranged for, on the basis of the camera image (45), to select the target (5) and assign a class (51) to it and thus render it an identified object (24), to store the assigned class (51) and the object's position (53N, 53E) as a stored position (58N, 58E) in said second memory (82) for display as symbols (22s) in said chart plotter (1).

The system's identification unit (7) is in an embodiment of the invention arranged for working on the basis of the camera image (45).The system may be arranged such that it allows an automatic AlS-based assigned class be suggested in a class assignment menu guide in connection with the camera image (45) at the chart plotter (1), whereafter a confirmation and choice of one of the suggested identifications that the operator sees in the image (45) and thus acceptance of the automatically suggested class, an identification will be made on the basis of the camera image (45). Other vessel's AIS signal may, due to several reasons, such as GPS-errors, unsatisfactory GPS updating frequency, etc., comprise a rather erroneous position indication. The radar may designate an erroneous or missing radar identification for other vessels. The system according to the invention may be arranged so as for having other position information about other nearby vessels near what one may see in the camera (52), such that the camera image (45) and the recovery system may furnish one or more suggestions concerning what is currently observed in the camera image (45), whereupon the operator is asked to select the most relevant class identification or select a different and more relevant class to be assigned to the object.

During recovery operations the actual point in time (58t) of making an observation may be of essential importance, e.g. due to drift, and also due to the fact that a person may not reside for long periods of time in the sea before facing seriously negative consequences. This results in that for several situations one must prioritise the task of rescuing persons from the water before the task of rescuing persons who have managed to enter rafts or lifeboats. The recovery system according to the invention is thus provided with a clock which also assigns the point in time (58t) for the storage of the assigned class (51) and the stored position (58N, 58E) and stores the point in time (58t) with this information in said second memory (82).

In an embodiment of the invention the recovery system's identification unit (7) comprises a manual input or acoustic speech recognition input unit (72). This input unit (72) may be placed in local connection with the chart plotter (1) and be arranged as a menu selection input unit (74) either arranged directly as part of the screen image, or as an interrogating system comprising acoustic speech recognition within the chart plotter (1). The manual input may be operated using an interactive pointer system either as a touch screen pointer for selecting positions in the chart plot or items in the image. The manual input may further trigger the menu selection input unit (74) to present optional actions. Such an input unit (74) may also be arranged on the deck by the pointing unit (3). The menu selection input unit (74) may thus be arranged for allowing an operator to manually select between alternative classes to be assigned, this in order for having available the most probable potential classes, and an omnibus term named "other", with the classes being predetermined so as for the user not to assign classes in an imprecise way.

The recovery system according to the invention may in an embodiment be so arranged that the identification unit (7) is provided with an automatic classification unit (76) arranged for automatically assigning a class (51) to the target (5). Such a classification may take place based e.g. on the targets (5) degree of reflection or other reflection characteristics or based on the color spectrum of said target (5). Further, the classification may take place by image recognition said image recognition being known in the background art. A class assignment of the target (5) may also take place based on radar response identification acquired using the vessel's own radar. Classification of the object (5) may furthermore take place by comparing by means of the camera's main axis' (31) position (5N, 5E) for the axis' intersection with the sea, compared to one of the received positions from said position receiver (21), and wherein the classification may take place on the basis of the identification belonging to the received positions which to a sufficient degree corresponds with the camera's aiming position (5E, 5N).

For items or persons unintentionally floating about in the sea, these are in most instances not provided with navigational equipment such as GPS and AIS. In an embodiment of the invention illustrated in Fig. 3 the system is arranged for collecting objects' (24) information pertaining to position and identification (24^ 53Ni, 53E₁, ID₁), .., (24_N, 53N_N, 53E_N, ID_N) from the second memory (82) and sequentially broadcast information via its AIS- unit (21) as if this information pertaining to position and identification (24^ 53N₁, 53E₁, ID₁), .., (24_N, 53N_N, 53E_N, ID_N) etc. belonged to each particular of said objects (24^ .., 24_N) etc. and if it was sent out from each particular object's AlS-transmitter, of which they are actually not in possession. Thus the system will contribute so as for the objects (24₁, .., 24_N) to seemingly emit AlS-information about themselves via said system's own vessel's AIS (21) so as for vessels who do not have systems corresponding to the invention but only an ordinary AIS connected to an ordinary chart plotter, will be able to observe these objects (24^ .., 24_N) on their own chart plotters.

In an embodiment of the invention the alternative classes (51) to be assigned to the objects (24) may be selected among items in a group. Such items may comprise the following classes and their subclasses: Vessel (ship, lifeboat, raft, floating platform, disabled ship),

Drifting items (flotsam, container, life buoy, barrels, life vests),

Pollution (oil slick, foam cover, lost cargo),

Persons (presumed alive, presumed deceased, uncertain),

Navigational mark (stake, spar buoy, light), Land (rock awash, island, rock which covers and uncovers, mainland), or

Unknown / other. The second memory (82) of said search system may in an embodiment be arranged for exchanging classified objects' (24) assigned class (51) and stored position (58N, 58E) with other vessels' corresponding recovery systems. This may occur via radio or optical signals, and may preferably take place automatically, but manual updating should be enabled in case an automatic updating line should fail. For those occurrences wherein a target (5), e.g. an object represented by a person (24^ being in the water and having been assigned a class as "person, alive", and where this person has confirmedly been rescued and taken into a boat, either confirmed by the boat itself or via visual observation from another vessel or confirmed via radio, the recovery system according to the invention may be arranged so as for the second memory (82) to delete the record of the object, i.e. the person (240, or reassign the object's (24i) assigned class (51) and stored position (58N, 58E) to "person, salvaged", as the object (24) has been handled and is not of current interest after having been rescued. While the information pertaining to the rescued object (24^ is deleted or amended, this information should be communicated to other units of the recovery system on other vessels so as for as many as possibly of the participating parties with a search system are kept up to date about the development of the recovery operation. One may thus avoid vessels from trying to rescue persons who have already been rescued, or trying to find goods that has been handled by other vessels.

In an embodiment illustrated in Fig. 1 the chart plotter's (1) chart display is arranged to consecutively display a line of sight (31') representing the camera's (52) main axis' (31) projection vertically down on the surface plane. This is meant only to be a line of sight but facilitates the interpretation of what is observed in the camera image (45). There is, as an example, illustrated two islands (Island A and Island B) in the camera image (45) on either sides of the aiming circle (55) and thus the camera main axis (31), whereby one will intuitively recognize those two islands in the map when one considers their position relative to the line of sight (31') representing the camera main axis (31). In an embodiment of the invention names of geographical details being displayed in the camera (52) may be shown. Their names may be collected from manual or automatic identification in the camera image (45), or automatically by a combination of position of the camera axis and a given position from the map or the map memory. Indication of geographical names in the camera image (45) will facilitate the use of the camera image (45) in the recovery system.

An ordinary, rectangular stationary camera image with four corners usually corresponds to a trapezoid of the stationary, photographically imaged or scanned part of the sea surface, given that all four corners of the camera recording surface really image the sea surface and do not point above the horizon. Given the extent of the camera image (45) and the characteristic parameters of the lens it is easily calculated to find those of the projected trapezoid's corners that are projected on the sea surface. An embodiment of the recovery system is arranged so as for the chart section (4) to comprise one or more marked trapezoids (46) which correspond to the area portions of the sea surface that is, or have been seen or registered in the camera image (45), and arranged so as for those marked trapezoids' positions, orientations and extent to be stored and marked as searched areas in at least one of the first or second memories (8, 82), and arranged for exchanging parameters pertaining to the searched trapezoids (46) with other vessels with corresponding recovery systems, in order to avoid that the same areas of the sea surface be searched several times by different vessels. An additional improvement with respect to the stationary searched trapezoids (46) explained above is that the marked searched trapezoids (46) may be given a deviation and indicated as drifted trapezoids (46') with a deviation corresponding to the weather and the currents' calculated or observed deviation effect on drifting objects such as people, oil slicks, flotsam, lifeboats, passively drifting ships, platforms adrift, etc., in order to facilitate the selection of new relevant search areas, and to indicate with a certain probability that items that have not been found despite thorough searching in a trapezoid in its original geographical position may not be found in an area having indicated deviation from the original geographical position, so that one may direct the efforts to potentially non-searched areas. If an object (24) is recognized with certain individual identification several times with steadily changing position one is also given a basis for calculating the deviation of other objects (24) with a given position for a given point in time, so as for increasing the probability of retrieving the objects (24) at a later point in time. The recovery system according to the invention is thus arranged such that a stored position in the second memory (82) for display by symbols (24) in the chart plotter (1) is updated with regard to calculated or observed deviation due to weather and current.

Claims

1. A marine search system comprising the following features:

- a chart plotter (1) for displaying a chart section (4) from a nautical chart representation in a first memory,

- a vessel position sensor (10) arranged for transmitting the vessel's (2) position to said chart plotter (1), said chart plotter (1) being arranged for projecting a symbol for said vessel's (2) position and heading in said chart section,

- a position receiver (21) arranged for receiving other vessels' (22) or objects' (24) position and possibly their identity, whereby the chart plotter (1) is arranged for projecting symbols for vessels (22) or objects in said chart section (4); wherein said recovery system further comprises:

- a pointing unit (3) arranged for directing a stabilized main axis towards a target (5) vessel or object (22, 24) in the vicinity of the vessel (2) and arranged for calculating the target's (22, 24) position,, a memory for storing said position,

- said pointing unit comprising one or more cameras arranged for sending a camera image (45) for being displayed in said chart plotter (1) with an aiming circle representing said main axis, said camera being stabilized so as for compensating for roll motion about said stabilized main axis so as for forming said camera image (45) non-rotating on said chart plotter (1),

- said chart plotter (1) arranged for displaying a camera chart pointer symbol in a position which represents said main axis' intersection with the surface and provided with a camera command device for moving said camera chart pointer symbol to a new desired position in said chart section and thus command the steering of said main axis towards said new desired position;

- said chart plotter's (1) camera image (45) being arranged for displaying an image pointer symbol for a camera image (45) steering device, in which a change of the position of said image pointer symbol contributes to commanding the rotation of said main axis towards a new desired position for said main axis' intersection with the surface;

- an identification unit (7) connected to said pointing unit arranged for, on the basis of said camera image (45) to select and assign to said target (5) a class, and further for storing said assigned class and said target's (5) position as an object with a stored position in a second memory for display as symbols in said chart plotter (1).

2. The recovery system of claim 1 , in which also a point in time for the storing of said assigned class and said stored position are stored together with these in said second memory.

3. The recovery system of claim 1 , in which said identification unit (7) comprises a manual or acoustic speech recognition input unit.

4. The recovery system according to claim 1 , in which said identification unit (7) comprises a menu selection input unit arranged for allowing a user to manually choose between alternative potential classes.

5. The recovery system according to claim 1 , in which said position receiver comprises an AIS unit.

6. The recovery system according to claim 1 , in which said identification unit (7) is provided with an automatic classification unit arranged for assigning a class to said target (5) for it to become an identified object, e.g. based on degree of reflection, color spectrum, image recognition, radar response identification, or position comparison with another of the position receivers¹ received positions which to a sufficient degree corresponds with said camera's main axis' position.

7. The recovery system according to claim 4, in which alternative potential classes of a target (5) as an object are selected among items in the group of:

Vessel (ship, lifeboat, raft, platform, disabled ship),

Navigational mark (stake, spar buoy, light),

Drifting items (flotsam, container, life buoy, barrels, life vests),

Pollution (oil slick, foam cover, lost cargo),

Persons (presumably alive, presumably deceased, uncertain),

Land formations (rock awash, island, rock which covers and uncovers, mainland), or

Unknown / other.

8. The recovery system according to claim 6, in which alternative potential classes of a target (5) as an object are selected among items in the group of:

Vessel (ship, lifeboat, raft, platform, disabled ship), Navigational mark (stake, spar buoy, light), Drifting items (flotsam, container, life buoy, barrels, life vests), Pollution (oil slick, foam cover, lost cargo), Persons (presumably alive, presumably deceased, uncertain),

Unknown / other.

9. The recovery system according to claim 1 , in which said second memory is arranged for exchanging an object's assigned class and stored position with recovery systems on other vessels.

10. The recovery system according to claim 1, in which said second memory is arranged for deleting, or reassigning an object to another assigned class and stored position if said object is handled and thus no longer relevant after retrieval.

11. The recovery system according to claim 1 , in which said chart plotter (1 ) is arranged for continuously displaying a line of sight representing the camera's main axis' projection vertically down onto the surface.

12. The recovery system of claim 1 , in which said camera command device and said camera image (45) steering device is comprised in one and the same control device.

13. The recovery system according to claim 1, in which said chart section comprises one or more marked trapezoids which correspond to those areas of the surface which are or have been seen or registered in said camera image, and arranged such that these marked trapezoids' positions, orientations, and extent, are stored and marked as searched areas in at least one of said memories, and arranged for exchanging information pertaining to said searched trapezoids with other vessels having corresponding recovery systems.

14. The recovery system according to claim 12, in which said marked trapezoids are given a drift property and marked as drifted trapezoids having a deviation corresponding to the weather and the current's calculated or observed deviation effect on drifting objects for facilitating the selection of new relevant search areas.

15. The recovery system of claim 1, wherein a stored position in said second memory for being displayed by symbols in said chart plotter (1) are updated with respect to calculated or observed drift due to weather and current.

16. The recovery system of claim 1, wherein said pointing unit is arranged for providing directional parameters for calculating said target's position based on said vessel's position and heading and angular state (roll, pitch, yaw) in the sea.

17. The recovery system of claim 1 , in which said chart plotter (1) is arranged for projecting a radar image over said chart section.

18. The recovery system according to claim 5, further arranged for retrieving other objects' information pertaining to position and identification from said second memory and retransmit this information via said AlS-unit as if said position and identification were transmitted from each single of said objects.

19. The recovery system according to claim 1, said camera being stabilized so as for compensating for roll motion about said stabilized main axis so as for forming said camera image non-rotating on said chart plotter (1) using a motor (60) arranged for counter-rotating said camera (52) about said stabilized main axis (31) based on the roll and pitch angles measured for said vessel.