Advanced warning ice detection system for aircraft

• US 6,819,265 B2
• Filed: 08/22/2002
• Issued: 11/16/2004
• Est. Priority Date: 08/22/2002
• Status: Expired due to Term

• Current Assignee: Rosemount Aerospace, Inc. (Raytheon Technologies Corporation d/b/a RTX)
• Original Assignee: Rosemount Aerospace, Inc. (Raytheon Technologies Corporation d/b/a RTX)
• Inventors: Ray, Mark D., Jamieson, James R.
• Primary Examiner(s): TWEEL JR, JOHN ALEXANDER
• Application Number:
  US10/225,610
• Publication Number:
  US 20040036630A1
• Time in Patent Office: 817 Days
• Field of Search: 340/962, 340/580, 340/968, 342/26, 701/14
• US Class Current: 340/962
• CPC Class Codes: B64D 15/20 Means for detecting icing or initiating de-icing
• CPC Class Codes: G01N 21/21 Polarisation-affecting properties G01N21/19 takes precedence
• CPC Class Codes: G01S 17/42 Simultaneous measurement of distance and other co-ordinates indirect measurement G01S17/46
• CPC Class Codes: G01S 17/87 Combinations of systems using electromagnetic waves other than radio waves
• CPC Class Codes: G01S 17/95 for meteorological use
• CPC Class Codes: G01S 7/4802 using analysis of echo signal for target characterisation; Target signature; Target cross-section
• CPC Class Codes: G01S 7/499 using polarisation effects
• CPC Class Codes: G08B 19/02 Alarm responsive to formation or anticipated formation of ice
• CPC Class Codes: Y02A 90/10 Information and communication technologies [ICT] supporting adaptation to climate change, e.g. for weather forecasting or climate simulation

Abstract

An ice detection warning system mountable on board an aircraft for inflight monitoring of the airspace ahead of the aircraft comprises: a first plurality of optical elements configured to direct a pulsed laser beam at a first wavelength from a laser source into the airspace ahead of the aircraft; a second plurality of optical elements configured to separate received backscattering of light from the laser beam into a plurality of predetermined wavelengths; a plurality of light detectors for detecting the light of the separated plurality of wavelengths, respectively, and generating respectively corresponding plurality of electrical signals representative of the light detected thereby; and a processor for processing the plurality of electrical signals to determine if airspace conditions ahead of the aircraft are likely to cause ice accretion on the surface of the aircraft, and for generating a warning indicative thereof. In one embodiment, the warning system includes an optical scanner operative to scan the pulsed laser beam into the airspace ahead of the aircraft with a predetermined scan pattern, the scanner also being operative to receive the backscattering of light from the pulsed laser beam and direct it to the second plurality of optical elements which is configured to separate the received backscattering of light into the plurality of predetermined wavelengths.

Claims

1. A warning system mountable on board an aircraft for inflight monitoring of the airspace ahead of the aircraft for conditions likely to cause ice accretion on the surface of the aircraft and provide a warning thereof, said system comprising:

a laser source for generating a pulsed laser beam at a first wavelength;

a first plurality of optical elements configured to direct said pulsed laser beam into the airspace ahead of the aircraft;

a second plurality of optical elements for receiving the backscattering of light from said pulsed laser beam, said second plurality of optical elements configured to separate the received backscattering of light into a plurality of predetermined wavelengths;

a plurality of light detectors for detecting the light of the separated plurality of wavelengths, respectively, and generating respectively corresponding plurality of electrical signals representative of the light detected thereby; and

a processor for processing said plurality of electrical signals to determine if airspace conditions ahead of the aircraft are likely to cause ice accretion on the surface of the aircraft, and for generating a warning indicative thereof.

2. The system of claim 1 wherein the processor is operative to receive a temperature signal representative of the temperature of the airspace and process said temperature signal along with the plurality of electrical signals to determine if airspace conditions ahead of the aircraft are likely to cause ice accretion on the surface of the aircraft and the rate at which said ice accretion is likely to occur.

3. The system of claim 1 wherein the processor is operative to receive a speed signal representative of the speed of the aircraft and process said speed signal along with the plurality of electrical signals to determine if airspace conditions ahead of the aircraft are likely to cause ice accretion on the surface of the aircraft and the rate at which said ice accretion is likely to occur.

4. The system of claim 1 wherein the second plurality of optical elements includes:

a first optical element for separating light substantially at the first wavelength from the received backscattering of light; and

a second optical element for separating the separated light at the first wavelength into first and second polarization states;

wherein the plurality of light detectors include;

a first light detector for detecting the separated light of the first polarization state and generating a first electrical signal representative thereof; and

a second light detector for detecting the separated light of the second polarization state and generating a second electrical signal representative thereof; and

wherein the processor is operative to process the first and second electrical signals to determine the likelihood of ice accretion in the airspace.

5. The system of claim 4 wherein the processor is operative to determine a form of the water present in the airspace based on the ratio of the first and second electrical signals.

6. The system of claim 4 wherein the second plurality of optical elements further includes:

a third optical element for separating light substantially at a second wavelength and light substantially at a third wavelength from the received backscattering of light;

said light at said second wavelength being representative of a quantity of water molecules present in the airspace and said light at said third wavelength being representative of a quantity of air molecules present in the airspace;

wherein the plurality of light detectors include;

a third light detector for detecting the separated light at the second wavelength and generating a third electrical signal representative thereof; and

a fourth light detector for detecting the separated light at the third wavelength and generating a fourth electrical signal representative thereof; and

wherein the processor is operative to process the first, second, third and fourth electrical signals to determine the likelihood of ice accretion in the airspace.

7. The system of claim 6 wherein the processor is operative to determine a measure of water to dry air in the airspace based on a ratio of said third and fourth electrical signals and a measure of aerosols in the airspace based on a ratio of a combination of the first and second electrical signals and the fourth electrical signal.

8. The system of claim 1 wherein the second plurality of optical elements includes:

a third optical element for separating light substantially at a second wavelength and light substantially at a third wavelength from the received backscattering of light;

said light at said second wavelength being representative of a quantity of water molecules present in the airspace and said light at said third wavelength being representative of a quantity of air molecules present in the airspace;

wherein the plurality of light detectors include;

a third light detector for detecting the separated light at the second wavelength and generating a third electrical signal representative thereof; and

a fourth light detector for detecting the separated light at the third wavelength and generating a fourth electrical signal representative thereof; and

wherein the processor is operative to process the third and fourth electrical signals to determine the likelihood of ice accretion in the airspace.

9. The system of claim 8 wherein the processor is operative to determine a measure of water to dry air in the airspace based on a ratio of said third and fourth electrical signals.

10. The system of claim 1 wherein the first plurality of optical elements includes an optical scanner operative to scan the pulsed laser beam into the airspace with a predetermined pattern.

11. The system of claim 1 including an optical element for collecting the backscattering of light and focusing the collected light along an optical path directed to the second plurality of optical elements.

12. The system of claim 1 wherein the first plurality of optical elements is configured to direct the laser beam into the airspace substantially along a heading of the aircraft.

13. A warning system mountable on board an aircraft for inflight monitoring of the airspace ahead of the aircraft for conditions likely to cause ice accreation on the surface of the aircraft and provide a warning thereof, said system comprising:

a laser source for generating a pulsed laser beam at a first wavelength;

a first plurality of optical elements configured to direct said pulsed laser beam along a first optical path;

an optical scanner disposed in said first optical path and operative to scan said pulsed laser beam into the airspace ahead of the aircraft with a predetermined scan pattern, said scanner also operative to receive the backscattering of light from the pulsed laser beam and direct said backscattering along a second optical path;

a second plurality of optical elements for receiving the backscattering of light from said second optical path, said second plurality of optical elements configured to separate the received backscattering of light into a plurality of predetermined wavelengths;

a plurality of light detectors for detecting the light of the separated plurality of wavelengths, respectively, and generating respectively corresponding plurality of electrical signals representative of the light detected thereby; and

a processor for processing said plurality of electrical signals to determine if airspace conditions ahead of the aircraft are likely to cause ice accretion on the surface of the aircraft, and for generating a warning indicative thereof.

14. The system of claim 13 wherein the optical scanner is operative to scan the scan pattern of the pulsed laser beam azimuthally in relation to the heading of the aircraft.

15. The system of claim 13 wherein the optical scanner is operative to scan the scan pattern of the pulsed laser beam in elevation in relation to the heading of the aircraft.

16. The system of claim 13 including means for determining the location of the laser beam in the predetermined scan pattern and generating a location signal indicative thereof;

and wherein the processor is operative to process the plurality of electrical signals and the location signal to determine if airspace conditions ahead of the aircraft are likely to cause ice accretion on the surface of the aircraft and a location of said condition.

17. The system of claim 16 including a display for presenting data in a two dimensional image of the scanned airspace;

and wherein the processor is operative to determine a value for the likelihood of ice accretion corresponding to each of a plurality of locations in the scanned airspace and to plot said likelihood values according to their associated locations in the two dimensional image of the display.

18. The system of claim 17 wherein the processor is operative to plot the likelihood values in a color coded format in the two dimensional image of the display.

19. The system of claim 13 wherein the first and second optical paths comprise fiber optic cables.

20. The system of claim 13 wherein the optical scanner comprises a scan head mountable to a surface of the aircraft remotely located from the first and second pluralities of optical elements.

21. The system of claim 20 wherein the first and second optical paths comprise fiber optic cables coupling the scan head optically to the first and second pluralities of optical elements.

22. The system of claim 13 wherein the optical scanner and certain optical elements of the warning system are common to a LIDAR system also mountable on-board the aircraft.

23. The system of claim 13 wherein the optical scanner and certain optical elements of the warning system are common to a laser obstacle awareness system (LOAS) also mountable on-board the aircraft.