# US 11,079,486 B2 · Method of verifying a potential detection of a man overboard event and alert verification processing apparatus

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- Number: US 11,079,486 B2
- Document ID: US11079486B2
- Status: Granted
- Kind: B2
- Application number: 16/096,880
- Filed: 2017-04-28
- Published: 2019-05-09
- Granted: 2021-08-03
- Earliest claimed: 2016-04-29
- Assignees: MARSS Ventures S.A.
- Applicants: MARSS Ventures S.A.
- Inventors: Marco Cappelletti; Alberto Baldacci
- Web page: https://patentgrep.com/patent/US11079486B2

## CPC

- G01S 13/886: {for alarm systems (alarms with electrical actuation G08B13/22)}
- B63C 9/0005: {by means of alarm devices for persons falling into the water, e.g. by signalling, by controlling the propulsion or manoeuvring means of the boat (alarms responsive to presence of persons in a body of water in general G08B21/08)}
- G01S 13/72: for two-dimensional [2D] tracking, e.g. combination of angle and range tracking, track-while-scan radar
- G01S 13/723: {by using numerical data}
- G01S 13/88: Radar or analogous systems specially adapted for specific applications (electromagnetic prospecting or detecting of objects, e.g. near-field detection, G01V3/00)
- G06V 20/52: Surveillance or monitoring of activities, e.g. for recognising suspicious objects (recognising microscopic objects G06V20/69)
- G08B 21/08: responsive to the presence of persons in a body of water, e.g. a swimming pool; responsive to an abnormal condition of a body of water
- G01S: RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- B63C: LAUNCHING, HAULING-OUT, OR DRY-DOCKING OF VESSELS; LIFE-SAVING IN WATER; EQUIPMENT FOR DWELLING OR WORKING UNDER WATER; MEANS FOR SALVAGING OR SEARCHING FOR UNDERWATER OBJECTS (floating nets, floating slipways, or the like for recovering aircraft from the water B63B35/52)
- G06V: IMAGE OR VIDEO RECOGNITION OR UNDERSTANDING
- G08B: SIGNALLING SYSTEMS, e.g. PERSONAL CALLING SYSTEMS; ORDER TELEGRAPHS; ALARM SYSTEMS

## Abstract

A method of verifying a potential detection of a man overboard event recorded as a moving object in a plurality of sequential frames of image data in respect of a duration of a time window comprises receiving (900) ranging track data in respect of the time window. A geometric chord is then identified that intersects a start point and an end point of a path described by a ranging track of the ranging track data. A height of the start point and an angle defined by a convergence of the chord and a vertical are then determined (902, 906). The height and the angle are then compared relative to a boundary line in order to classify (910) the path described by the ranging track in relation to a man overboard event, thereby validating the potential detection.

## Claims

### Claim 1

A method of verifying a potential detection of a man overboard event recorded as a moving object in a plurality of sequential frames of image data in respect of a duration of a time window, the method comprising:
receiving ranging track data in respect of the time window;
identifying a geometric chord intersecting a start point and an end point of a path described by a ranging track of the ranging track data;
determining a height of the start point;
determining an angle defined by a convergence of the chord and a vertical;
comparing the height and the angle relative to a boundary line in order to classify the path described by the ranging track in relation to a man overboard event; and
verifying the potential detection of the man overboard event in response to the classification of the path described by the ranging track.

### Claim 2 (depends on 1)

The method according to claim 1, wherein the boundary line is defined by a first parameter and a second parameter.

### Claim 3 (depends on 2)

The method according to claim 2, wherein the first parameter is height and the second parameter is angle.

### Claim 4 (depends on 1)

The method according to claim 1, wherein the boundary line is based upon empirical data.

### Claim 5 (depends on 4)

The method according to claim 4, wherein the empirical data comprises clusters of pairs of height and angle data.

### Claim 6 (depends on 1)

The method according to claim 1, further comprising:
receiving an alert indicative of the potential detection of the man overboard event; and
disregarding the alert when evaluation of the ranging track data by the comparison of the height and the angle relative to the boundary line results in a determination that the ranging track data does not relate to the man overboard event.

### Claim 7 (depends on 1)

The method according to claim 1, wherein classification of the path described by the ranging track data as corresponding to the man overboard event comprises evaluation of the height and the angle relative to a predetermined boundary line extending in a height-angle plane.

### Claim 8 (depends on 1)

The method of filtering alerts caused by wave motion from alerts caused by a man overboard event comprising the method of verifying a detection of a potential man overboard event according to claim 1.

### Claim 9

A method of configuring a radar track analyser for verification of a man overboard event, the method comprising:
receiving a plurality of ranging track data sets;
for each of the plurality of ranging track data sets:
identifying a respective geometric chord intersecting a respective start point and a respective end point of a path described by a ranging track of the ranging track data;
determining a respective height of the respective start point;
determining a respective angle defined by a respective convergence of the respective chord and a vertical;
recording the respective height, the respective angle and a respective verified man overboard event status corresponding to the respective height and respective angle; and
identifying a first cluster of height and angle pairs and a second cluster of height and angle pairs; and
determining a boundary between the first and second clusters of height and angle pairs.

### Claim 10 (depends on 9)

The method according to claim 9, wherein the boundary corresponds to a two-dimensional threshold.

### Claim 11

An alert verification processing apparatus for verifying a potential detection of a man overboard event recorded as a moving object in a plurality of sequential frames of image data in respect of a duration of a time window, the apparatus comprising:
a processing resource arranged to receive ranging track data in respect of the time window; wherein
the processing resource is arranged to identify a geometric chord intersecting a start point and an end point of a path described by a ranging track of the ranging track data;
the processing resource is arranged to support a comparator, an angle calculator and a height calculator;
the height calculator is arranged to determine a height of the start point;
the angle calculator is arranged to determine an angle defined by a convergence of the chord and a vertical; and
a comparator is arranged to compare the height and the angle relative to a boundary line in order to classify the path described by the ranging track in relation to a man overboard event; and
the comparator is arranged to verify the potential detection of the man overboard event in response to the classification of the path described by the ranging track.

### Claim 12 (depends on 11)

The apparatus according to claim 11, wherein the boundary line is defined by a first parameter and a second parameter.

### Claim 13 (depends on 12)

The apparatus according to claim 12, wherein the first parameter is height and the second parameter is angle.

### Claim 14 (depends on 11)

The apparatus according to claim 11, wherein the boundary line is based upon empirical data.

### Claim 15 (depends on 14)

The apparatus according to claim 14, wherein the empirical data comprises clusters of pairs of height and angle data.

### Claim 16 (depends on 11)

The apparatus according to claim 11, wherein
the processing resource is arranged to receive an alert indicative of the potential detection of the man overboard event; and
the processing resource is arranged also to disregard the alert when evaluation of the ranging track data by the comparison of the height and the angle relative to the boundary line results in a determination that the ranging track data does not relate to the man overboard event.

### Claim 17 (depends on 11)

The apparatus according to claim 11, wherein classification of the path described by the ranging track data as corresponding to the man overboard event comprises the comparator evaluating the height and the angle relative to the boundary line extending in a height-angle plane.

### Claim 18 (depends on 11)

An alert filtering apparatus for filtering alerts caused by wave motion from alerts caused by a man overboard event, the apparatus comprising the alert verification processing apparatus according to claim 11.

### Claim 19

A configuration apparatus for a radar track analyser for verification of a man overboard event, the apparatus comprising:
a processing resource arranged to receive a plurality of ranging track data sets; wherein
for each of the plurality of ranging track data sets, the processing resource is arranged to:
identify a respective geometric chord intersecting a respective start point and a respective end point of a path described by a ranging track of the ranging track data;
determine a respective height of the respective start point;
determine a respective angle defined by a respective convergence of the respective chord and a vertical;
record the respective height, the respective angle and a respective verified man overboard event status corresponding to the respective height and respective angle; and
the processing resource is further arranged to identify a first cluster of height and angle pairs and a second cluster of height and angle pairs; and
the processing resource is arranged to determine a boundary between the first and second clusters of height and angle pairs.

### Claim 20 (depends on 19)

The apparatus according to claim 19, wherein the boundary corresponds to a two-dimensional threshold.