System for the detection and the depiction of objects in the path of marine vessels

• US 8,665,122 B2
• Filed: 08/12/2009
• Issued: 03/04/2014
• Est. Priority Date: 08/12/2008
• Status: Active Grant

• Current Assignee: Kongsberg Discovery As
• Original Assignee: Kongsberg Seatex AS (Government of Norway)
• Inventors: Klepsvik, John O.
• Primary Examiner(s): Bugg, George
• Assistant Examiner(s): Afrifa-Kyei, Anthony D
• Application Number:
  US13/055,003
• Publication Number:
  US 20110128162A1
• Time in Patent Office: 1,665 Days
• Field of Search: 340/985
• US Class Current: 340/985
• CPC Class Codes: G01S 17/10 using transmission of interrupted, pulse-modulated waves determination of distance by phase measurements G01S17/32
• CPC Class Codes: G01S 17/42 Simultaneous measurement of distance and other co-ordinates indirect measurement G01S17/46
• CPC Class Codes: G01S 17/89 for mapping or imaging
• CPC Class Codes: G01S 17/93 for anti-collision purposes

Abstract

System for detection and depiction of objects in the path of marine vessels and for warning about objects that may constitute a risk to the navigational safety. The system includes a sweeping unit for illumination of objects within the field of view of the system, including a light source which emits a beam within the field of view of the system, an optical sensor and pulse processing unit including optical detectors for monitoring of the beam output power and generation of a start pulse for measurement of distance, for detection/reception of radiant energy reflected from objects, including measurement of distance to the reflecting object(s) based on the time delay between emitted and reflected light, including energy and peak effect of the pulses. The sweeping unit sweeps the beam and the optical detector'"'"'s instantaneous field of view over the sweep area, by means of first and second sweeping mechanisms, to obtain directional information related to the instantaneous radiation direction relative to the vessel.

Claims

1. A system for detection and imaging of objects (16) in the course of speed boats and other marine vessels and for warning about objects that may constitute a risk to the navigational safety, said vessels preferably exhibiting a navigation and communication system (28), said system comprising a scanning unit (10) for laser illumination of objects (16) within the field of view of the system, including a control unit (11) and an operator panel (12), characterized in that the scanning unit (10) includes:

a light source (30), preferably an eye-safe IR laser provided to emit a laser beam (33) within the field of view of the system,

an optics/sensor- and pulse processing unit (21) including optical detectors (34, 38) for monitoring the output power of the laser beam (33) and generation of trigger pulses for measurement of distances to objects (16), for reception/detection of radiant energy reflected from objects (16), including measurement of distance to the reflecting object(s) (16) based on the time delay between emitted and reflected light, including energy and peak power of the pulses,

a first (19) and second (20) scanning mechanism,

said scanning unit (10) being arranged to generate a regular pattern of laser spots on a water surface, where partly overlapping laser spots (17) are generated along radial scan lines (18) from the vessel by means of the first scanning mechanism (19) and by rotating the scan lines about a vertical axis by means of the second scanning mechanism (20) so that the entire or parts of the water surface around the vessel is covered with overlapping laser spots.

2. System in accordance with claim 1, characterized in that the scanning unit (10) is arranged to stabilize the scan area both in the horizontal and vertical plane from roll and pitch movements of the vessel as well as short term deviations from the steered course.

3. System in accordance with claim 1, characterized in that the first scanning mechanism (19) comprises two counter-rotating beam deflection elements (43, 44), such as Risley prisms, optical transmission gratings, diffractive optical elements or similar, each said beam deviation elements (43, 44) being mounted in an electrical motor (45, 46), said beam deflection elements (43, 44) preferably rotating at the same but opposite speed, to scan the laser beam (33) and the receiver field of view along a vertical scan line (18).

4. System in accordance with claim 1, characterized in that the second scanning mechanism (20) comprises a rotating mirror (47), preferably arranged at approximately 45 degrees to the rotation axis of the second scanning mechanism (20), which second scanning mechanism (20) in combination with the first scanning mechanism (19) is arranged to move the vertical scan line (18) horizontally in a regular pattern, such that the selected scan area is covered by partly overlapping laser beams.

5. System in accordance with claim 3, characterized in that the first scanning mechanism (19) in combination with the second scanning mechanism (20) scan the laser beam (33) and the field of view along straight radial lines;

said lines being displaced in regular angular steps in horizontal direction synchronously with the first scanning mechanism (19).

6. System in accordance with claim 3, characterized in that the scan lines (18) which are generated in the first scanning mechanism (19) can be rotated a given angle about the rotational axis of the motors (45, 46) by adjusting the phase of the motor (46) for the second beam deflection element (44) in relation to the phase of the motor (45) of the first beam deflection element (43).

7. System in accordance with claim 3 characterized in that the scan lines (18) from the first scanning mechanism (19) are rotated synchronously with the rotation of the second scanning mechanism (20), so that the lines remain fixed in relation to the plane of incidence of the mirror (47), normal to the mirror surface.

8. System in accordance with claim 2, characterized in that roll, pitch and yaw angles are measured and transformed into a set of correction angles for the system.

9. System in accordance with claim 3, characterized in that the first scanning mechanism (19) corrects for deviation from verticality by adjusting the phase of the motor (46) for the beam deflection element (44) relative to the phase of the motor of the deflection element (43) such that the linescan angle is rotated an angle relative to the normal plane of the mirror in the second scanning mechanism (20) corresponding to the calculated correction angle, and/or that

the second scanning mechanism (20) corrects for deviation in azimuth by rotating the mirror (47) an angle corresponding to the calculated correction angle, and/or that

the second scanning mechanism (20) also corrects deviation in elevation by rotating (tilting) the mirror (47) about an axis normal to the rotational axis of the second scanning mechanism, an angle corresponding to the calculated correction angle.

10. System in accordance with claim 1, characterized in that the control unit (11) includes a scan motor controller (24) arranged to control speed and phase of the motors (45, 46) and emission of laser pulses, so that the laser spots obtain a fixed mutual distance both horizontally and vertically within the scan area.

11. System in accordance with claim 1, characterized in that the system is arranged to receive data from the navigation and communication system (28) of a vessel for measurement of steered course, speed and attitude (roll, pitch, yaw) and the video display system of a vessel for presentation of information.

12. System in accordance with claim 1, characterized in that the control unit (11) includes an image and control processor (27) provided with means and/or software to generate a monitor image on the operator panel (12), where the intensity of the returned signals and 3D position are shown both in a central projection as for a camera and in a vertical projection as for a radar.

13. System in accordance with claim 1, characterized in that the image and control processor (27) is provided with means and/or software to analyze the returned signals for detection of other vessels or objects (16) within the field of view of the system, generate standardized graphical symbols on the monitors and send standardized messages, such as NMEA/IEC, to other navigation systems, such as ECDIS or Radar, about calculated position, CPA, TCPA as well as course and speed for detected objects (16).

14. System in accordance with claim 1, characterized in that the image and control processor (27) is provided with means and/or software to send a standardized alarm message to the vessel'"'"'s alarm system if CPA to the objects (16) are within a defined safety zone of the vessel.