Fiber optic aircraft load relief control system

• US 4,692,610 A
• Filed: 01/30/1986
• Issued: 09/08/1987
• Est. Priority Date: 01/30/1986
• Status: Expired due to Fees

• Current Assignee: Grumman Aerospace Corporation (Northrop Grumman Corporation)
• Original Assignee: Grumman Aerospace Corporation (Northrop Grumman Corporation)
• Inventors: Szuchy, Nicholas C.
• Primary Examiner(s): NOT, DEFINED
• Assistant Examiner(s): Wieland, Charles
• Application Number:
  US06/824,124
• Time in Patent Office: 586 Days
• Field of Search: 250/227, 250/231 P, 73/800, 73/802, 356/32, 356/34
• US Class Current: 250/227.14
• CPC Class Codes: G01B 11/18 using photoelastic elements
• CPC Class Codes: G01L 1/247 using distributed sensing elements, e.g. microcapsules along a single optical fibre G01L1/242

Abstract

A fiber optic load measuring system is disclosed comprising an optical pulse generator, an optical bus, a plurality of optical pulse routing switches, a plurality of optical attenuators disposed along the surface where the load is to be measured, a plurality of optical pulse routing switches, and a signal processor. The optical attenuators are each connected to a dedicated optical pulse routing switch and are adapted to vary the attenuation of the optical pulse in response to the applied load. The optical pulse routing switches are adapted to selectively direct the optical pulses to individual optical attenuators, such that each of the optical attenuators is separately and sequentially pulsed.

Claims

1. A fiber optic load measuring system comprising:

(a) an optical pulse generator;

(b) an optical bus connected to said optical pulse generator;

(c) a plurality of optical pulse routing switches serially disposed along the length of said optical bus;

(d) a plurality of optical attenuators, each of said optical attenuators being disposed along a dedicated surface where an applield load is to be measured, each of said optical attenuators further being connected to a dedicated optical pulse routing switch and being operative to vary the attenuation of the optical pulse in response to the applied load as said optical pulse is reflected by said optical attenuators;

(e) said optical pulse routing switches being operative to selectively direct said optical pulses to individual optical attenuators such that each of said optical attenuators is separately pulsed;

(f) an optical pulse receiver connected to said optical bus and operative to receive optical pulses reflected from said optical attenuators; and

(g) a signal processor connected to said optical receiver and operative to process the signal received by said optical pulse receiver to determine the load along each of said surfaces.

2. The system as recited in claim 1 further including an optical pulse delay element, said delay element being disposed so as to interface said optical pulse generator and said optical pulse receiver with said optical bus, said optical pulse delay element being operative to delay optical pulses communicated between said optical bus and said optical pulse generator, and between said optical bus and said pulse receiver.

3. The system as recited in claim 1 wherein said optical pulse generator and said optical pulse receiver comprise a reflectometer.

4. The system as recited in claim 1 wherein said optical attenuators are operative to vary the intensity of the optical pulse reflected thereby in accordance with the load applied along the surface where the optical attenuator is disposed.

5. The system as recited in claim 4 wherein said optical attenuators are operative to linearly vary the optical pulse reflected thereby in response to instantaneous variations in the applied load.

6. The system as recited in claim 1 wherein said optical attenuators comprise serpentined optical fibers.

7. The system as recited in claim 1 wherein said pulse delay element comprises a spool having a predetermined length of optical fiber.

8. The system as recited in claim 1 wherein said optical attenuators each comprise a length of fiber optic material having at least one curved portion, said curved portion being deformable in response to an applied load, said curved portion being dimensioned such that light optical pulses passing therethrough are attenuated in linear relation to the instantaneous deformation of said curved portions in response to the applied load.

9. The system as recited in claim 8 wherein said curved portions have a bend radius dimensioned so as to attenuate optical pulses passing therethrough in linear relation to the deformation of said curved portion in response to the applied load.

10. The system as recited in claim 8 wherein said curved portion is dimensioned to provide static attenuation of the light passing therethrough, said curved portion also being dimensioned to provide variable dynamic attenuation of optical pulses passing therethrough, said dynamic attenuation being linearly related to the instantaneous deformation of said curved portion in response to the applied load.

11. A method of measuring the load applied to a surface comprising communicating a plurality of optical pulses to an optical bus;

disposing a plurality of optical pulse routing switches along the length of said optical bus;

disposing a plurality of optical attenuators along a surface where a load is to be measured, each of said optical attenuators being disposed along a dedicated surface portion and connected to a dedicated optical pulse routing switch;

selectively directing said optical pulses to individual optical attenuators such that each of said optical atttenuators is separately pulsed;

receiving optical pulses reflected from said optical attenuators; and

processing said received optical pulses to determine the load along each of said surface portions.

12. The method as recited in claim 11 wherein said step of disposing a plurality of optical attenuators comprises the step of bending a length of fiber optic material so as to form an optical attenuator, the degree of bending being selected such that the optical conductivity of the fiber optic material will vary in linear relation to the instantaneous load applied to the fiber optic material.

13. The method as recited in claim 11 wherein said step of disposing a plurality of optical attenuators includes the step of bending a length of fiber optic material so as to form an optical attenuator, the degree of bending being selected such that the bent fiber optic material provides static attenuation of optical pulses passing therethrough, the bent portion further providing variable dynamic attenuation of light passing therethrough, said dynamic attenuation being linearly related to the instantaneous deformation of said bent portion in response to the applied load.

14. The method as recited in claim 11 wherein said step of selectively routing optical pulses comprises the step of generating a plurality of substantially identical optical pulses;

communicating said substantially identical pulses to said optical bus; and

sequentially directing one of said optical pulses to each of said optical attenuators in a sequence determined by the location of said dedicated optical pulse routing switches.