FIBER-OPTIC BASED TRAFFIC AND INFRASTRUCTURE MONITORING SYSTEM

• US 20190137305A1
• Filed: 05/09/2017
• Published: 05/09/2019
• Est. Priority Date: 05/09/2016
• Status: Active Grant

• Current Assignee: Optics11 B.V.
• Original Assignee: Fugro Technology BV
• Inventors: KARABACAK, Devrez Mehmet, SINGER, Johannes Maria, KNOPPERS, German Enrique, O'DOWD, John
• Granted Patent: US 10,458,818 B2
• Time in Patent Office: Days
• CPC Class Codes: E01F 11/00 Road engineering aspects of Embedding pads or other sensitive devices in paving or other road surfaces , e.g. traffic detectors, vehicle-operated pressure-sensitive actuators, devices for monitoring atmospheric or road conditionspressure-sensitive elements G01L; traffic control systems G08G
• CPC Class Codes: G01D 5/353 influencing the transmission properties of an optical fibre
• CPC Class Codes: G08G 1/015 with provision for distinguishing between two or more types of vehicles, e.g. between motor-cars and cycles
• CPC Class Codes: G08G 1/02 using treadles built into the road pads or other sensitive devices responsive to passage of vehicles E01F11/00
• CPC Class Codes: G08G 1/04 using optical or ultrasonic detectors
• CPC Class Codes: G08G 1/052 with provision for determining speed or overspeed speed measuring in general G01P

Abstract

In an arrangement of a traffic infrastructure and an optic sensor system (10, 20), the traffic infrastructure has a traffic carrying surface (51) for providing support of conveyance elements (92) of a vehicle (90), therewith allowing movements of the vehicle over the traffic carrying surface. The optic sensor system (10, 20) comprising an interrogator (10) and at least one fiber optic sensor (20) arranged below the traffic carrying surface that is coupled to the interrogator. The at least one fiber optic sensor (20) comprising an optic fiber (21) with a plurality of optic strain-sensor elements (22) distributed over its length. The plurality of optic strain-sensor elements (22) have mutually different optical characteristics, e.g. a mutually different characteristic wavelength. The interrogator (10) is configured to transmit an optical interrogation signal into the at least one fiber optic sensor, to receive a response optical signal modulated by said fiber optic sensor, and to identify changes in the optical characteristics of the response optical signal resulting from strains induced in said optic strain-sensor elements as a result of a conveyance element (92) of a vehicle (90) moving over the traffic carrying surface (51) across said at least one fiber optic sensor. wherein the at least one fiber optic sensor (20) extends at least substantially according to a straight line in a direction at least substantially parallel to the traffic carrying surface.

Claims

1. An arrangement comprising:

a traffic infrastructure comprising;

a traffic carrying surface to support at least one conveyance elements of a vehicle, therewith allowing movements of the vehicle over the traffic carrying surface; and

an optic sensor system comprising;

at least one fiber optic sensor coupled to an interrogator and extending at least substantially according to a straight line in a direction at least substantially parallel to the traffic carrying surface, the at least one optic sensor comprising;

an optic fiber with a plurality of optic strain-sensor elements distributed over its length, wherein the plurality of optic strain-sensor elements have mutually different optical characteristics, and

the interrogator arranged below the traffic carrying surface and being configured to;

transmit an optical interrogation signal into the at least one fiber optic sensor,

receive a response optical signal that has been modulated by the fiber optic sensor based on its optical characteristics, and

identify changes in the optical characteristics of the response optical signal resulting from strains induced in the optic strain-sensor elements as a result of the conveyance element of the vehicle moving over the traffic carrying surface across the at least one fiber optic sensor.

2. The arrangement according to claim 1, wherein the at least one fiber optic sensor is provided with at least one anchor element that extends around the at least one fiber optic sensor between mutually subsequent optic strain-sensor elements, the at least one anchor element having a circumference in a plane transverse to a longitudinal direction of the at least one fiber optic sensor that is at least 1.5 times larger than a circumference of the fiber optic sensor in a plane transverse to the longitudinal direction at a position of an optic strain-sensor element.

10. The arrangement according to claim 1, wherein the at least one fiber optic sensor is arranged in a direction transverse to a longitudinal direction of the traffic infrastructure.

12. The arrangement according to claim 1, wherein the at least one fiber optic sensor is arranged in a direction longitudinal along the direction of the traffic infrastructure

15. The arrangement according to claim 1, wherein the interrogator is configured to derive a set of signal features indicative for a shape of a temporal pattern of the response optical signal.

16. The arrangement according to claim 1, wherein the interrogator is configured to derive a set of signal features by using a model that relates properties of the conveyance element and or its kinetic state to a shape of the temporal pattern.

19. The arrangement according to claim 1, wherein the interrogator is configured to extract a spatial pattern indicative for a spatial footprint of a plurality of tires of a vehicle.

22. The arrangement according to claim 1, wherein respective optical signals of the plurality of optic strain-sensor elements of the at least one fiber optic sensor are processed to estimate a distance between a pair of tires on a same axle of the vehicle.

23. The arrangement according to claim 1, wherein respective optical signals of the plurality of optic strain-sensor elements of the at least one fiber optic sensor obtained for a first time-interval are processed to correlate those signals with respective optical signals of the plurality of optic strain-sensor elements of the at least one fiber optic sensor in another time interval.

26. The arrangement according to claim 1, wherein the at least one fiber optic sensor is one of a plurality of mutually parallel fiber optic sensors that are spaced relative to each other in the traffic direction.

29. The arrangement according to claim 1, wherein the at least one fiber optic sensor is arranged in a trench inside a traffic carrying layer defining the traffic carrying surface or is arranged between a support layer and a traffic carrying layer carried by the support layer.

36. The arrangement according to claim 1, wherein the optic fiber further comprises a pair of a first and a second optic strain-sensor element with at least substantially the same optical characteristics in their neutral state, and arranged at mutually opposite sides of a longitudinal section of the at least one fiber optic sensor, and wherein the interrogator is configured to estimate a change in a gap between the first and the second optic strain-sensor element based on an interference between response optic signals received from the first and second optic strain-sensor elements.

37. The arrangement according to claim 1, further comprising at least one optic sensor element below the traffic infrastructure surface that is mechanically decoupled from the traffic infrastructure in a longitudinal direction of the fiber optic sensor.

39. The arrangement according to claim 37, wherein the at least one optic sensor element that is mechanically decoupled in a longitudinal direction is at least substantially mechanically decoupled in any direction, wherein the interrogator module is arranged for determining a temperature based on response optical signals obtained from the mechanically decoupled optic sensor element.

48. The arrangement according to claim 1, wherein the interrogator is configured to process response optical signals of mutually neighboring optic strain sensor elements to determine a relative position of a conveyance element between the mutually neighboring optic strain sensor elements, using a model that relates a relationship between the response optical signals to the relative position.

49. The arrangement according to claim 1, wherein the interrogator includes a conversion module to convert an optic response signal into a detection signal having a magnitude indicative for a detected strain of the at least one optic strain sensor element.

50. The arrangement according to claim 49, wherein the interrogator further includes a signal filter to determine low-frequency components in the detection signal, and to further process the low frequency components to derive signal features related to a mechanical behavior of the traffic infrastructure.

62. The arrangement according to claim 1, further comprising a plurality of optic strain-sensor elements that are distributed in a longitudinal direction of the road, wherein the interrogator is configured to track motion of a vehicle in the longitudinal direction by associating subsequent response optic signals from respective ones of the optic strain-sensor elements associated with a traversal of the vehicle, to determine a magnitude of these subsequent response optic signals, therewith obtaining a time series of magnitudes and to determine whether a variation is present in the time series.

63. The arrangement according to claim 62, wherein the at least one fiber optic sensor is one of a plurality of fiber optic sensors that are arranged at mutually different longitudinal positions transverse to a longitudinal direction of the road, and wherein the plurality of optic strain-sensor elements that are distributed in a longitudinal direction of the road comprise optic strain-sensor elements of respective ones of the plurality of fiber optic sensors.

67. The arrangement according to claim 1, wherein the interrogator includes a temperature estimation module to estimate a value for a temperature of an optic strain-sensor element and a compensation module using the estimated value to compensate a response optic signal received from the optic strain-sensor element for temperature.

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