Method and System For Determining a Velocity of a Relative Movement Between an Object and a Fluidal Medium

• US 20150116696A1
• Filed: 05/30/2013
• Published: 04/30/2015
• Est. Priority Date: 06/05/2012
• Status: Active Grant

• Current Assignee: NewSouth Innovations Pty Limited (University Of New South Wales)
• Original Assignee: NewSouth Innovations Pty Limited (University Of New South Wales)
• Inventors: O'Byrne, Sean Brendan, Wittig, Sven Marc
• Granted Patent: US 9,874,580 B2
• Time in Patent Office: Days
• US Class Current: 356/28
• CPC Class Codes: G01F 1/661 using light
• CPC Class Codes: G01F 1/662 Constructional details
• CPC Class Codes: G01F 1/663 by measuring Doppler frequency shift
• CPC Class Codes: G01F 1/712 using auto-correlation or cross-correlation detection means
• CPC Class Codes: G01P 3/36 Devices characterised by the use of optical means, e.g. using infrared, visible, or ultraviolet light G01P3/68 takes precedence; gyrometers using the Sagnac effect, i.e. rotation-induced shifts between counter-rotating electromagnetic beams G01C19/64
• CPC Class Codes: G01P 5/26 by measuring the direct influence of the streaming fluid on the properties of a detecting optical wave

Abstract

Disclosed is a method and a system for determining a velocity of a relative movement between a system for determining the velocity and a fluidal medium. The method includes directing at least two light beams through at least a portion of the fluidal medium using the system such that a portion of light of each light beam is absorbed by the fluidal medium. Further, the method includes detecting first and second spectral intensity profiles of at least two light beams to detect the light absorption. The method also includes determining a difference profile associated with spectral intensity differences between a first and a second spectral intensity profile; and integrating an absolute value function of the difference profile to determine the velocity. The at least two light beams are directed such that the first and second spectral intensity profiles each have a different spectral position. The system has components that are arranged to allow operation of the above-described method.

Claims

1. A method of determining a velocity of a relative movement between a system for determining the velocity and a fluidal medium, the method comprising the steps of:

directing at least two light beams through at least a portion of the fluidal medium using the system such that a portion of light of each light beam is absorbed by the fluidal medium;

detecting first and second spectral intensity profiles of the at least two light beams to detect the light absorption;

determining a difference profile associated with spectral intensity differences between a first and a second spectral intensity profile; and

performing an operation that results at least in an approximation of an integral of an absolute value function of the difference profile to determine the velocity;

wherein the at least two light beams are directed

such that the first and second spectral intensity profiles each have a different spectral position.

2. The method of claim 1 wherein the step of performing an operation that results at least in an approximation of an integral of an absolute value function of the difference profile is performed such that a value is generated that is a function of the velocity.

3. The method of claim 2 wherein the function of the velocity is a monotonic function for a given pressure and temperature of the fluidal medium.

4. The method of claim 1 wherein the step of performing an operation that results at least in an approximation of an integral comprises integrating an absolute value function of the difference profile to determine the velocity.

5. The method of claim 1 wherein the fluidal medium is a gaseous medium.

6. The method of claim 1 wherein the system is arranged on or in a moving object.

7. The method of claim 6 wherein the moving object is an aircraft.

8. The method of claim 1 wherein the at least two light beams are directed such that the spectral position of each spectral intensity profile is indicative of the velocity.

9. The method of claim 1 wherein the at least two light beams are directed through air and a portion of light of the at least two light beams is absorbed by oxygen molecules of the air.

10. The method of claim 1 wherein two light beams are directed such that the spectral profile associated with one of the light beams experiences a spectral shift in opposite spectral direction than the spectral profile of associated with the other one of the light beams as a function of the velocity.

11. The method of claim 1 wherein the step of performing an operation that results at least in an approximation of an integral comprises determining a value that is indicative of the velocity.

12. A system for determining a velocity of a relative movement between the system and a fluidal medium, the system comprising:

a light source for generating at least two light beams and directing the at least two light beams through at least a portion of the fluidal medium during a relative movement between the system and a fluidal medium such that a portion of light of each light beam is absorbed by the fluidal medium;

a detector arrangement for detecting spectral intensity profiles of the at least two light beams to detect the light absorption; and

a processor for determining the velocity using the spectral intensity profiles;

wherein the system is arranged to direct the at least two light beams through at least a portion of the fluidal medium such that each spectral intensity profile has a different spectral position.

13. The system of claim 12 wherein the system is arranged to generate a value that is a function of the velocity.

14. The system of claim 13 wherein the function of the velocity is a monotonic function for a given pressure and temperature of the fluidal medium.

15. The system of claim 12 wherein the fluidal medium is a gaseous medium.

16. The system of claim 12 wherein the system is arranged on or in an object.

17. The system of claim 12 wherein the at least two light beams are directed such that the spectral position of each light beam is indicative of the velocity.

18. The system of claim 12 wherein the system is arranged to direct two light beams in directions that are substantially anti-parallel relative to each other.

19. The system of claim 12 wherein the system is arranged such that the at least two light beams originate from one light source.

20. The system of claim 12 wherein the light source comprises at least one laser.

21. The system of claim 20 wherein the at least one laser is a vertical cavity surface emitting laser (VCSEL).

22. The system of claim 12 further comprising a respective light source for each light beam.

23. The system of claim 19 further comprising an optical beam splitter that is arranged to receive light and is arranged to split the received light into the at least two beams of light.

24. The system of claim 12 wherein the at least two light beams are guide at least partially by optical fibres to and from the fluidal medium.

25. The system of claim 12 wherein the processor comprises a differential amplifier.

26. The system of claim 12 wherein the processor comprises an analogue circuit.