Real time imaging system and method for use in aiding a landing operation of an aircraft in obscured weather conditions

• US 6,119,055 A
• Filed: 12/22/1998
• Issued: 09/12/2000
• Est. Priority Date: 01/23/1998
• Status: Expired due to Fees

• Current Assignee: Mcdonnell Douglas Corporation (The Boeing Co.)
• Original Assignee: Mcdonnell Douglas Corporation (The Boeing Co.)
• Inventors: Richman, Isaac
• Primary Examiner(s): Nguyen, Tan
• Assistant Examiner(s): Hernandez, Olga
• Application Number:
  US09/218,227
• Time in Patent Office: 630 Days
• Field of Search: 701/16, 701/1, 340/945, 340/948, 340/947, 340/960, 342/33, 342/63, 244/183, 244/81, 244/75 R, 244/1, 318/583
• US Class Current: 701/16
• CPC Class Codes: G08G 5/0013 with a ground station
• CPC Class Codes: G08G 5/0026 located on the ground
• CPC Class Codes: G08G 5/025 Navigation or guidance aids radar or analogous systems specially adapted for landing purposes G01S13/913

Abstract

An imaging apparatus for aiding landing of aircraft in weather conditions obscuring a pilot'"'"'s view of a runway. The apparatus comprises a plurality of LED assemblies which are disposed along the runway. Each LED assembly includes a plurality of LEDs, a receiver and a plurality of drivers responsive to the receiver for energizing the LEDs. The LEDs of each LED assembly are pulsed on by signals from a transmitter disposed adjacent an end of the runway. The transmitter also sends synchronization signals to a receiver located on board the approaching aircraft. The receiver on the aircraft is coupled to a processor which uses the synchronization signals to determine when the LEDs are energized and when they are not energized. The processor controls a CCD camera mounted on the aircraft so as to obtain an unobstructed view of the approaching runway. The processor controls the CCD camera such that the camera takes images (i.e., frames) while the LEDs are pulsed on and also while the LEDs are off. The frames with the LEDs off are then digitally subtracted from the frames taken while the LEDs were energized to produce enhanced images which are output to a visual display on-board the aircraft and which do not include the objectionable radiant background information. In an alternative embodiment a plurality of independent groups of LED assemblies are controlled in accordance with separate synchronization frequencies. The pilot is instructed which synchronization frequency to select, and only the LED assemblies corresponding to the selected group appear as being continuously illuminated on board the visual display on the aircraft.

Claims

1. A method for increasing visibility of areas of an airport or airfield to aid an operator of an aircraft in visualizing said areas during weather conditions which obscure the operator'"'"'s vision of said areas, the method comprising the steps of:

disposing a first plurality of radiant energy sources adjacent a first area of said airport or airfield;

disposing a second plurality of radiant energy sources adjacent a second area of said airport or airfield;

controllably turning on and off said first plurality of radiant energy sources;

controllably turning on and off said second plurality of radiant energy sources;

using a camera placed on said aircraft to obtain images of said pluralities of radiant energy sources;

synchronizing operation of said camera to a selected one of said pluralities of radiant energy sources to obtain at least one image while said selected plurality of radiant energy sources is turned off and at least one image while said selected plurality of radiant energy sources is turned on; and

subtracting said image obtained while said selected plurality of radiant energy sources is turned off from the image obtained while said selected plurality of radiant energy sources is turned on, in real time, to produce a filtered image which provides said operator with an enhanced visual representation of said selected plurality of radiant energy sources to thereby assist said operator in visually discerning an area adjacent said selected plurality of radiant energy sources.

2. An apparatus for increasing a runway visual range (RVR) to aid an operator of an aircraft in visualizing a runway upon a landing approach during weather conditions obscuring the operator'"'"'s view of said runway, said apparatus comprising:

a plurality of light emitting diode (LED) assemblies disposed along opposite sides of said runway, each said LED assembly including at least one LED, an LED driver circuit and a radio frequency receiver, each one of said LED assemblies operating to help delineate an outline of said runway when said LEDs are energized;

a radio frequency transmitter disposed adjacent said runway for providing a radio frequency signal synchronized with an AC power signal powering said LEDs which is received by said radio frequency receiver of each one of said LED assemblies to cause said LED of each one of said assemblies to be energized intermittently in synchronization with the frequency of said AC power signal provided to said LED assemblies, said radio frequency transmitter further transmitting radio frequency synchronization signals indicating when said LEDs are energized and when said LEDs are not energized;

an imaging system disposed on said aircraft, said imaging system comprising;

a radio frequency receiver for receiving said radio frequency synchronization signals and transmitting control signals in response thereto;

a camera mounted on said aircraft so as to be able to obtain an image of said runway as said aircraft approaches said runway;

a processor assembly responsive to said control signals for controlling said camera in accordance with said radio frequency synchronization signals such that said camera obtains a plurality of first images when said LEDs are energized and a plurality of second images when said LEDs are not energized;

said processor operating to subtract said second plurality of images from said first plurality of images to produce a plurality of filtered images representing enhanced visual images of said LEDs delineating said runway; and

a display for presenting said filtered images to said operator of said aircraft as said operator approaches said runway during a landing approach.

3. The apparatus of claim 2, wherein:

said camera comprises a charged coupled device (CCD) camera including a bandpass filter centered at a center wave length of said LEDs.

4. An apparatus for increasing the runway visual range (RVR) to aid an operator of an aircraft in visualizing areas of an airport or airfield during poor visibility weather conditions:

a first plurality of radiant energy sources disposed adjacent a first area of said airport or airfield;

a second plurality of radiant energy sources disposed adjacent a second area of said airport or airfield;

a first system for turning on and off said first plurality of radiant energy sources at a first frequency;

a second system for turning on and off said second plurality of radiant energy sources at a second frequency different from said first frequency;

an imaging system carried on board said aircraft, said imaging system including;

a camera mounted on said aircraft;

a processor for controlling operation of said camera and for processing images obtained by said camera;

a selector for enabling said operator to synchronize operation of said camera with one or the other of said pluralities of radiant energy sources; and

said camera operating to capture radiant energy images, in real time, from the selected plurality of radiant energy sources, said processor operating to control said camera to capture at least one radiant energy image of said selected plurality of radiant energy sources when said selected plurality of radiant energy sources is turned on, and at least one radiant energy image when said selected plurality of radiant energy sources is turned off, and to subtract said image obtained while said selected plurality of radiant energy sources is turned off from the image obtained while said selected plurality is turned on, to thereby produce a filtered radiant energy image providing an enhanced visual representation of said selected group of radiant energy sources.

5. The apparatus of claim 4, wherein said first system for turning on said first plurality of radiant energy sources comprises a first radio frequency transmitter;

and

wherein said second system for turning on said second plurality of radiant energy sources comprises a second radio frequency transmitter.

6. The apparatus of claim 5, further comprising a first clock for controlling said first radio frequency transmitter in accordance with said first frequency;

and

a second clock for controlling said second radio frequency transmitter in accordance with said second frequency.

7. The apparatus of claim 6, wherein said first system for turning on said first plurality of radio frequency transmitters operates to generate a radio frequency turn on signal which is transmitted simultaneously in real-time to said first plurality of radiant energy sources and to said imaging system of said aircraft;

and

wherein said second system for turning on said second plurality of radio frequency transmitters operates to generate a radio frequency turn on signal which is transmitted simultaneously in real-time to said second plurality of radiant energy sources and to said imaging system of said aircraft.

8. A method for increasing a runway visual range (RVR) to aid an operator of an aircraft in visualizing a runway upon a landing approach during weather conditions obscuring the operator'"'"'s view of said runway, said method comprising the steps of:

disposing a plurality of radiant energy sources adjacent said runway;

controllably intermittently energizing said radiant energy sources;

using a camera placed on said aircraft to capture a plurality of first images of said runway taken when said radiant energy sources are energized and a plurality of second images of said runway taken when said radiant energy sources are not energized; and

subtracting said second images from said first images to produce a plurality of filtered images, said filtered images comprising an enhanced representation of said radiant energy sources thereby serving to delineate said runway for said operator and improve said RVR despite said weather conditions.

9. The method of claim 8, further comprising the steps of:

disposing a radio frequency receiver on board said aircraft;

transmitting a radio frequency signal from a transmitter disposed adjacent said runway when said radiant energy sources are energized to synchronize said camera with the energization of said radiant energy sources such that said camera alternatively captures said first and second images.

10. The method of claim 8, wherein the step of subtracting said second images from said first images comprises using a processor to produce said filtered images.

11. The method of claim 8, wherein the energization of said radiant energy sources is synchronized with a frequency of an AC power source powering said radiant energy sources.

12. An apparatus for increasing the runway visual range (RVR) to aid an operator of an aircraft in visualizing a runway upon a landing approach during poor visibility weather conditions, said apparatus comprising:

at least one radiant energy source disposed in the vicinity of said runway for generating radiant energy signals;

a radiant energy receiver carried on board said aircraft for capturing said radiant energy signals as said aircraft approaches said runway during a landing approach, and for capturing radiant energy background signals when said radiant energy source is turned off; and

a processor carried on board said aircraft for subtracting said radiant energy background signals from said radiant energy signals, in real time, to produce a plurality of filtered images providing an enhanced visual representation of said radiant energy source delineating said runway to increase the RVR of said runway for said operator.

13. The apparatus of claim 12, further comprising a system for intermittently turning on and off said radiant energy source in synchronization with a frequency of an AC power source powering said radiant energy source.

14. The apparatus of claim 13, wherein said system further includes a transmitter for transmitting synchronization signals to said aircraft indicating when said radiant energy source is turned on and when said source is turned off;

and

wherein said apparatus further includes a receiver for receiving said synchronization signals and outputting signals to said processor to inform said processor when said radiant energy source is turned on and off.

15. The apparatus of claim 12, further comprising a display for displaying said filtered images to said operator.

16. The apparatus of claim 12, further comprising a plurality of groups of radiant energy sources;

and

a system for turning on and off each of said groups of radiant energy sources at different frequencies.

17. The apparatus of claim 16, wherein said radiant energy receiver on-board said aircraft is synchronized with the operation of only one of said groups of radiant energy sources.

18. An apparatus for increasing a runway visual range (RVR) to aid an Operator of an aircraft in visualizing a runway upon a landing approach during weather conditions obscuring the operator'"'"'s view of the runway, said apparatus comprising:

a radiant energy source disposed adjacent said runway so as to at least partially delineate said runway for generating a radiant energy signal;

a transmitting system for controllably energizing said radiant energy source to cause said radiant energy source to be pulsed on and off and for transmitting a synchronizing signal indicating that said radiant energy source has been pulsed on;

a radiant energy receiver disposed on said aircraft so as to be able to receive said radiant energy signals as said aircraft approaches said runway;

a signal receiver responsive to said synchronizing signal for turning on said radiant energy receiver intermittently to obtain pluralities of first and second images, said first images being obtained when said radiant energy source is being energized and including said radiant energy signals and radiant background information, and said second images being obtained when said radiant energy source is not being energized and including only said radiant background information;

a system for subtracting said plurality of second images from said plurality of first images to form a plurality of filtered images in which said radiant background information has been removed, said filtered images representing substantially only radiant energy from said radiant energy source and serving to provide an enhanced visual delineation of said runway; and

a display viewable by said operator of said aircraft for displaying said filtered images delineating said runway as said aircraft approaches said runway during a landing approach.

19. The apparatus of claim 18, wherein said system for subtracting said second images from said first images comprises a processor carried on said aircraft.

20. The apparatus of claim 18, wherein said display comprises a heads-up-display (HUD).

21. The apparatus of claim 18, wherein said system for controllably energizing said radiant energy source comprises a radio frequency transmitter;

and

wherein said radiant energy source includes a radio frequency receiver responsive to said radio frequency transmitter for turning on and off said radiant energy source; and

wherein said radio frequency transmitter operates to transmit said synchronizing signal.

22. The apparatus of claim 18, wherein said radiant energy source comprises a plurality of light emitting diodes (LEDs) disposed along said runway so as to define the bounds of said runway.

23. The apparatus of claim 18, wherein said radiant energy receiver comprises a camera.

24. The apparatus of claim 23, wherein said camera comprises a charge coupled device (CCD) camera having an optical bandpass filter;

and

wherein said radiant energy source comprises a plurality of light emitting diodes (LEDs); and

wherein said bandpass filter is centered at the center wave length of an optical signal provided by said LEDs.

25. An apparatus for increasing a runway visual range (RVR) to aid an operator of an aircraft in visualizing a runway upon a landing approach during weather conditions obscuring the operator'"'"'s view of said runway, said apparatus comprising:

a plurality of light emitting diode (LED) assemblies disposed along said runway so as to delineate the bounds of said runway, each one of said LED assemblies including a plurality of light emitting diodes (LEDs) and a radio frequency receiver operable to energize said LEDs upon receipt of a first radio frequency signal;

a radio frequency transmitter disposed adjacent said runway for intermittently generating said first radio frequency signal to cause said LEDs of each one of said LED assemblies to turn on for a predetermined time duration, said radio frequency transmitter also operating to transmit a radio frequency synchronizing signal;

a camera disposed on said aircraft at a position so as to be able to view said runway as said aircraft approaches said runway;

a radio frequency receiver disposed on said aircraft responsive to said synchronizing signal for turning on said camera while said LEDs are turned on to obtain a plurality of first images including radiant energy from said LEDs and radiant background energy, said radiant background energy tending to obscure said operator'"'"'s view of said runway, and for obtaining a plurality of images of second images of said runway when said LEDs are not turned on, said images of said runway when said LEDs are not turned on representing only said radiant background energy;

a processor for subtracting said plurality of second images from said plurality of first images to produce a plurality of filtered images representing substantially only said radiant energy from said LEDs; and

a display for displaying said filtered images to said operator of said aircraft as said operator approaches said runway upon a landing approach.

26. The apparatus of claim 25, wherein each one of said LEDs of each of said LED assemblies is pulsed on approximately 15 times per second;

and

wherein each said on pulse has a duration of approximately 13 milliseconds.

27. The apparatus of claim 25, wherein said camera is turned on approximately 30 times per second to provide said plurality of first images and said plurality of second images.

a display viewable by said operator of said aircraft for displaying said filtered images delineating said runway as said aircraft approaches said runway during a landing approach.

28. The apparatus of claim 25, wherein said display comprises a video monitor.

29. The apparatus of claim 28, wherein said selector enables said operator of said aircraft to switch synchronization of said system, in real time, from one of said plurality of radiant energy sources to the other.

30. The apparatus of claim 25, wherein said camera comprises a charge coupled device (CCD) camera.

31. The apparatus of claim 30, wherein said CCD camera includes a bandpass filter centered at a LED center wave length of said LEDs to thereby permit said camera to reject at least a portion of said radiant background energy.

32. The apparatus of claim 30, wherein said CCD camera provides a horizontal field of view (FOV) of approximately between about 40°

-20°

.