METHOD FOR MONITORING THE ENVIRONMENT OF A VEHICLE

Description

BACKGROUND OF THE INVENTION

[0001] The present invention relates to the field of preventing collisions with moving objects and more particularly between vehicles.

[0002] Traditionally, in the maritime domain, ships were fitted with a taximeter ("pelorus" in English) comprising a sighting alidade which could be pointed at a moving object to check the evolution of the bearing of this object: a lack of evolution of the bearing of the object revealed a risk of collision.

[0003] Ships are now equipped with automatic means of monitoring their environment, which include radar, an automatic identification radio system (AIS) and an optical surveillance device.

[0004] Document US-A-2014 / 0306997, for example, describes a method for radar monitoring the environment of a vehicle equipped with a radar. The position of surrounding objects is conventionally indicated by a symbol placed on a polar representation whose center is occupied by a symbol representing the vehicle equipped with the radar. It is intended to associate an AIS symbol with each surrounding object symbol.

[0005] Most radars are equipped with echo processing software to calculate the bearing and distance of the vehicle from the carrier vehicle, the vehicle's speed, and a closest point of approach (CPA) used to determine the risk of collision. However, the calculation of the closest point of approach is based on the assumption that the vehicle is moving in a straight line at the calculated speed, an assumption that may be incorrect. SUBJECT OF THE INVENTION

[0006] The invention aims in particular to improve collision prevention. SUMMARY OF THE INVENTION

[0007] For this purpose, a method is provided for monitoring a region in which a carrier is located, comprising the steps of: detecting, by means of at least one sensor of the first type, successive positions of a mobile following a trajectory in said region; displaying a polar representation having a center symbolizing the current position of the carrier and placing therein a first mobile symbol representing a current position of the mobile as a function of a bearing angle and a distance of the mobile relative to the carrier.

[0008] According to the invention, the method comprises the steps of: displaying around the polar representation an annular band whose width represents a predetermined monitoring duration; placing in the annular band second mobile symbols representing angular data of a trajectory of the mobile, the annular band and the polar representation having the same angular reference, the annular band having an inner circumference corresponding to a recent time and an outer circumference corresponding to a time past relative to the recent time of a duration equal to the predetermined monitoring duration and the second mobile symbols being placed all the closer to the outer circumference of the annular band the older the corresponding angular data.

[0009] The trajectory angular data is a bearing angle of the mobile relative to the carrier or an azimuth of the mobile. Thus, the polar representation makes it possible to visualize the relative positions of the mobiles and the carrier on a spatial scale while the annular band provides a temporal scale making it possible to visualize the direction relative to the carrier followed by the mobiles and therefore to assess the risks of collision that these mobiles pose to the carrier.

[0010] The invention also relates to a method above in which carrier symbols representing successive positions of the carrier during the predetermined monitoring time are placed in the annular band to highlight a variation in azimuth of the carrier during the predetermined monitoring time, the carrier symbols being placed closer to the outer periphery of the annular band the older the corresponding position.

[0011] According to another embodiment, the position of the mobile is also detected by at least one sensor of the second type, the sensor of the first type determining the position of the mobile in a first reference frame and the sensor of the second type determining the position of the mobile in a second reference frame, the method comprising the step of normalizing the first reference frame and the second reference frame, the position of the mobile used to position the first mobile symbol and the second mobile symbol resulting from a combination of the positions detected by the two sensors.

[0012] The invention further relates to a device for monitoring a region in which a wearer of the device is located, comprising a data processing computer unit which is connected to a display and to a data bus carrying positional data of mobiles located in the region of the wearer, the processing computer unit being programmed to implement the method of the invention.

[0013] Other characteristics and advantages of the invention will emerge from reading the following description of a particular and non-limiting embodiment of the invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Reference will be made to the attached drawings, including: There figure 1 is a schematic perspective view of a ship provided with a device allowing the implementation of the invention; The figure 2 is a schematic perspective view showing this device; The figure 3 is a view showing the display of this device and the display according to the invention. DETAILED DESCRIPTION OF THE INVENTION

[0015] With reference to the figures, the invention is described here in application to a ship or carrier 100 moving in a region R in which there are also mobiles 101, 102, 103 which are here other ships.

[0016] The carrier 100 is provided with at least one sensor of the first type, one sensor of the second type and one sensor of the third type which are arranged to determine the position of the mobiles respectively in a first reference frame, a second reference frame and a third reference frame. More precisely, the carrier 100 is provided with a radar sensor 1001, an AIS sensor 1002 and an optical sensor 1003 which are connected to a control unit 1004 of the carrier 100 by a data bus 1005 of the NMEA type to transmit to the control unit 1004 positional data of the mobiles 101, 102, 103. The sensors 1001, 1002, 1003 are arranged and controlled to detect successive positions of the mobiles 101, 102, 103 in the region R and provide the corresponding positional data. These sensors are known in themselves.It will simply be recalled that the radar system comprises an incident radar signal transmitter and a reflected signal sensor making it possible to measure in a polar reference a bearing of the mobile (orientation of the antenna), a distance from the mobile (time of flight) and a speed of the mobile (Doppler effect); the AIS sensor picks up radiofrequency signals which are sent by the mobiles and which contain an identification of the mobile, its declared position and the route followed in a geographical reference; the optical sensor comprises one or more cameras operating in the visible and possibly infrared range and making it possible to measure a bearing of the mobiles in a polar reference. The radar sensor 1001 and the AIS sensor 1002 allow the control unit to calculate a closest crossing point (CPA).

[0017] The carrier 100 is also provided with a device 1010 for monitoring the region R in which the carrier 100 is located. The device 1010 comprises a data processing computer unit 1011 which is connected to a display 1012 and to the data bus 1005. The computer unit 1011 comprises, in a manner known per se, a processor and a memory containing programs comprising instructions for implementing the method according to the invention.

[0018] The computer unit 1011 performs the steps of: recovering the positional data transmitted on the data bus 1005, normalizing the first reference mark, the second reference mark and the third reference mark, and calculating a consolidated position of each mobile 101, 102, 103 by combining the positions detected by the three sensors 1001, 1002, 1003 for each of the mobiles 101, 102, 103; determining a scrolling of the mobiles 101, 102, 103 relative to the carrier 100; displaying, on the display 1012, a polar representation 10 having a center symbolizing the current position of the carrier 100; placing in the polar representation 10 the first symbols of mobile 1, 2, 3 representing the current consolidated position of each of the mobiles 101, 102, 103 as a function of the bearing angle and the distance of each of the mobiles 101, 102, 103 relative to the carrier 100.

[0019] The computer unit 1011 performs the steps of: display around the polar representation 10 an annular band 20 whose width 1 represents a predetermined monitoring duration; place in the annular band 20 second mobile symbols 1', 2', 3' representing the successive bearing angles of each of the mobiles 101, 102, 103 relative to the carrier 100 to highlight the movement of each of said mobiles 101, 102, 103 relative to the carrier 100.

[0020] The angular reference of the annular band 20 is the same as that used for the polar representation 10. The predetermined monitoring duration depends on the speed of the carrier 100 and the speed of the mobiles which are likely to evolve in the region. In the maritime domain, the predetermined monitoring duration will be for example 30 minutes, or even 15 minutes. The annular band 20 has an inner periphery 21 corresponding to a recent time and an outer periphery 22 corresponding to a time past with respect to the recent time of a duration equal to the predetermined monitoring duration and the second mobile symbols 1', 2', 3' are placed all the closer to the outer periphery 22 of the annular band 20 as the corresponding bearing angle is old (bearing angles older than the predetermined monitoring duration are no longer represented).The inner periphery 21 of the annular band 20 is placed at a distance from the center of the polar representation 10 corresponding, in the polar representation, to an optical horizon of the optical sensor 1003. The optical horizon is for example located at a distance of around twenty nautical miles.

[0021] Furthermore, carrier symbols 0' representing successive headings of the carrier 100 during the predetermined monitoring duration are placed in the annular band 20 to highlight a variation in azimuth of the carrier 100 during the predetermined monitoring duration. The carrier symbols 0' are placed closer to the outer periphery 22 of the annular band 20 the older the corresponding heading is (headings older than the predetermined monitoring duration are no longer represented).

[0022] It is understood that this makes it easy for an operator to detect collision risks. On the figure 3, the operator can see that: the carrier 100 has not changed course (the carrier symbols 0' are aligned with the current course of the carrier); the bearing angle of the mobile 102 is constant (the second symbols of mobile 2' are aligned with the first symbol of mobile 2), that is to say that the scroll of the mobile 102 is zero, so that it represents a high risk of collision; the mobile 101 has a scroll less than 0 (the second symbols of mobile 1' are aligned with a direction that forms a non-zero angle with the direction of the first symbol of mobile 1 relative to the carrier) so that the mobile 101 is not dangerous; mobile 103 has a scroll whose sign has changed (the most recent second mobile 3' symbols are not aligned with the other second mobile 3' symbols even though the heading of carrier 100 has not changed) so that mobile 103 presents a potential risk of collision if its heading were to change again.

[0023] Computer unit 1011 finally executes: a first level alert step when the scrolling of at least one of the mobiles 101, 102, 103 is zero and the carrier has not changed course; a second level alert step when the scrolling of at least one of the mobiles 101, 102, 103 changes sign even though the carrier 100 has not changed course.

[0024] The alert can be visual: color change, flashing, or other. The alert can be audible: ringing or voice message for example.

[0025] The computer unit 1011 can also issue a reliability alert for the nearest crossing position calculations when changes in the sign of the scrolling of the mobiles or the carrier are detected.

[0026] Of course, the invention is not limited to the embodiment described but encompasses any variant falling within the scope of the invention as defined by the claims.

[0027] In particular, the invention is applicable to any type of nautical, aerial or terrestrial carrier. When the carrier is an aircraft, the data bus to which the computer unit is connected is the aeronautical data bus. In the aviation sector, the predetermined monitoring duration will be, for example, 3 minutes, or even 1 minute.

[0028] It should be noted that the second mobile symbol can represent either the bearing angle of the mobile relative to the carrier as in the example described or the heading followed by the mobile. In the latter case, it is not mandatory to have the carrier symbols in the annular band to represent changes in the carrier's heading since the variation in the heading of the mobiles is independent of the variations in the carrier's heading.

Claims

1. A method of monitoring a region (R) in which a carrier (100) is located, the method comprising the steps of: · using at least one sensor (1001) of a first type to detect successive positions of a moving body (101, 102, 103) following a path in said region (R); and · displaying a polar plot (10) having a center symbolizing the current position of the carrier (100) and having placing thereon a first moving-body symbol (1, 2, 3) representing the current position of the moving body (101, 102, 103) as a function of the bearing angle and of the distance of the moving body (101, 102, 103) relative to the carrier (100); the method being characterized in that it further comprises the steps of: · displaying an annular band (20) around the polar plot (10), the band being of width (ℓ) that represents a predetermined monitoring duration; and · placing second moving-body symbols (1', 2', 3') in the annular band (20), the second symbols being representative of successive readings of angles along the path of said moving body (101, 102, 103), the annular band (20) having an inner outline (21) corresponding to a recent time and an outer outline (22) corresponding to a past time preceding the recent time by a duration equal to the predetermined monitoring duration, and the second moving-body symbols (1', 2', 3') being placed closer to the outer outline (22) of the annular band (20) with increasing age of the corresponding angle readings.

2. A method according to claim 1, wherein the angle readings are bearing angles of the moving body (101, 102, 103) relative to the carrier (100).

3. A method according to claim 1, wherein the angle readings are azimuths of the moving body (101, 102, 103).

4. A method according to any preceding claim, wherein carrier symbols (0') representing successive positions of the carrier (100) during the predetermined monitoring duration are placed in the annular band (20) in order to show any variation in the azimuth of the carrier (100) during the predetermined monitoring duration, the carrier symbols (0') being placed closer to the outer outline (22) of the annular band (20) with increasing age of the corresponding position.

5. A method according to any preceding claim, wherein the positions of the moving body (101, 102, 103) are also detected by at least one sensor (1002) of a second type, the sensor (1001) of the first type determining the position of the moving body in a first reference frame and the sensor (1002) of the second type determining the position of the moving body in a second reference frame, the method including the step of normalizing the first and second reference frames, with the positions of the moving body (101, 102, 103) that are used for positioning the first and second moving-body symbols (1, 2, 3; 1', 2', 3') resulting from a combination of the positions detected by both sensors.

6. A method according to the preceding claim, wherein the positions of the moving body are also detected by a sensor (1003) of a third type.

7. A method according to claim 6, wherein the moving body is detected by means of a radar sensor (1001), by means of an AIS sensor (1002), and by means of an optical sensor (1003).

8. A method according to any one of claims 1 to 4, wherein the moving body is detected by an optical sensor (1003).

9. A method according to claim 8, wherein the inner outline (21) of the annular band (20) is placed at a distance from the center of the polar plot (10) that corresponds, in the polar plot, to the optical horizon of the optical sensor.

10. A method according to any preceding claim, including a first level warning step when the transverse movement of the moving body (101, 102, 103) is zero.

11. A method according to claim 10, including a second level warning step when the transverse movement of the moving body (101, 102, 103) changes sign.

12. A device (1010) for monitoring a region (R) in which a carrier (100) of the device (1010) is located, the device comprising a computer unit (1011) for processing data, which unit is connected to a display unit (1012) and to a data bus (1005) conveying position data of moving bodies (101, 102, 103) that are located in the region (R) of the carrier (100), the computer unit (1011) being programmed to perform the method according to any preceding claim.

13. A device according to claim 12, wherein the carrier (100) is a ship including an NMEA type bus forming the data bus (1005) to which the computer unit (1011) is connected.

14. A device according to claim 12, wherein the carrier (100) is an aircraft, and the data bus (1005) is an aviation data bus.