Detection device to be installed on a road for detecting environmental conditions and monitoring and controlling traffic

• US 20050072907A1
• Filed: 09/14/2004
• Published: 04/07/2005
• Est. Priority Date: 10/02/2003
• Status: Active Grant

• Current Assignee: C.R.F. Societa Consortile Per Azioni
• Original Assignee: C.R.F. Societa Consortile Per Azioni
• Inventors: Darin, Marco, Visintainer, Filippo, Mosca, Emilio, Repetto, Piermario, Liotti, Luca, Pallaro, Nereo
• Granted Patent: US 7,817,183 B2
• Time in Patent Office: Days
• US Class Current: 250/215
• CPC Class Codes: G01J 1/4228 arrangements with two or more detectors, e.g. for sensitivity compensation
• CPC Class Codes: G01N 21/538 for determining atmospheric attenuation and visibility
• CPC Class Codes: G08G 1/04 using optical or ultrasonic detectors
• CPC Class Codes: G08G 1/096716 where the received information does not generate an automatic action on the vehicle control
• CPC Class Codes: G08G 1/09675 where a selection from the received information takes place in the vehicle
• CPC Class Codes: G08G 1/096758 where no selection takes place on the transmitted or the received information
• CPC Class Codes: G08G 1/096783 where the origin of the information is a roadside individual element
• CPC Class Codes: G08G 1/096791 where the origin of the information is another vehicle
• CPC Class Codes: H04N 7/181 for receiving images from a plurality of remote sources

Abstract

The invention describes a system with a multifunctional integrated visual sensor using a CMOS or CCD technology matrix having a sensitive area divided into sub-areas dedicated to a series of specific functions.

Claims

1. Detection device to be installed on roads or motorways or on traffic dividers so as to perform one or more functions among fog detection, lighting detection, traffic monitoring and control,

wherein it comprises sensor means including a CCD or CMOS matrix having a sensitive area divided into sub-areas by means of optical systems with different directions and/or fields of view and/or optical separation modes of said sub-areas.

2. Detection device according to claim 1, wherein it is installed on a series of portals placed at a given distance one from the other on a road portion.

3. Detection device according to claim 1, wherein it is installed on a control vehicle (for instance a safety car), for dynamically monitoring environmental and traffic conditions on a motorway.

4. Detection device according to claim 1, wherein said sensor means are designed to integrate the visibility functions related to the presence of mist, fog and fog banks, by combining active techniques (indirect, local and accurate measuring by means of emitters) with passive techniques (direct, extended and self-assured measuring).

5. Detection device according to claim 1, wherein said sensor means are designed to integrate the function of fog bank detection.

6. Detection device according to claim 1, wherein said sensor means comprise an outer temperature and relative humidity sensor, from which dew temperature can be obtained, which parameters are the inputs of a mathematic model predicting possible fog formation.

7. Detection device according to claim 1, wherein said sensor means are designed to integrate also lighting detection, together with visibility evaluation, so as to adjust the intensity of emergency lights on the concerned road portion and make them well visible to vehicles, thus avoiding dangerous phenomena of drivers'"'"' dazzling.

8. Detection device according to claim 1, wherein said sensor means are designed to integrate inner temperature detection for the self-adjustment of the response of sensor means.

9. Detection device according to claim 1, wherein said sensor means are designed to integrate traffic monitoring and control function.

10. Detection device according to claim 1, wherein said sensor means are designed to integrate a self-adjusting function as a result of partially dirty optical window, sensor temperature variation and power reduction of emitters.

11. Detection device according to claim 1, wherein said sensor means comprise a self-cleaning optical window or means for cleaning the latter.

12. Detection device according to claim 1, wherein in a possible arrangement the matrix has its sensitive area divided into sub-areas, each dedicated to the one of following functions:

traffic monitoring and control, visibility (passive technique), fog banks;

visibility (active technique);

environmental lighting;

dirt on optical window (active or passive technique);

operation of emitters.

13. Detection device according to claim 12, wherein the portion of the matrix sensitive area dedicated to passive fog detection also performs traffic monitoring and control functions.

14. Detection device according to claim 12, wherein environmental lighting function is performed by a specific sub-area of the matrix or by a sub-area contained in the one dedicated to traffic monitoring.

15. Detection device according to claim 12, wherein the function of dirt on optical window is performed in an active mode (i.e. via an emitter), but the receiver is separated from the visual matrix (though integrated into the device).

16. Detection device according to claim 12, wherein the function of dirt on optical window is performed in an active mode, but the receiver is the visual matrix itself, with a sub-area dedicated to said function or with a sub-area contained in the one dedicated to one of the aforesaid functions.

17. Detection device according to claim 12, wherein the function of dirt on optical window is performed in a passive mode (i.e. image analysis), in a matrix sub-area dedicated to said function or in a sub-area contained in the one dedicated to one of the aforesaid functions (for instance the sub-area dedicated to scene monitoring).

18. Detection device according to claim 12, wherein the monitoring of emitter operation consists in monitoring the emitted optical power through a sub-area dedicated to said function or through a photosensitive detector separated from the matrix or through an electronic circuit monitoring control current and environmental temperature.

19. Detection device according to claim 12, wherein the sub-area dedicated to scene monitoring and passive fog detection uses an objective with a convenient focal length, placed at a distance from matrix center.

20. Detection device according to claim 12, wherein according to a preferred feature the sub-area dedicated to scene monitoring and passive fog detection receives the optical signal through a system of microlenses.

21. Detection device according to claim 12, wherein the sub-area dedicated to fog function based on active technique receives the optical signal through a ball or GRIN (gradient of index) lens, or also no lens at all, in association with a glass or plastic optical fiber, if necessary with another GRIN or micro-optical lens, or also with no lens at all, in association with a high-pass/interferential filter 8, which could how ever also be absent, with a collection lens without filter or a collection lens provided with high-pass material with interferential coating.

22. Detection device according to claim 21, wherein in order to filter the disturbance deriving from environmental lighting, in addition or as an alternative to the optical filter, a LED modulated to a given frequency and an electronic band-pass filtering system at emitter frequency are used as emitter.

23. Detection device according to claim 21, wherein in order to filter the disturbance deriving from environmental lighting, the environmental lighting signal is used for calculating background intensity and subtracting it from fog detector signal.

24. Detection device according to claim 12, wherein in the sub-area dedicated to lighting function the optical signal is collected by means of an optical fiber made of plastic or glass.

25. Detection device according to claim 12, wherein lighting function can also be performed by calculating the average incident intensity on the area dedicated to traffic monitoring or to active fog detection, and in such a case the same optical component as in these functions can be used.

26. Detection device according to claim 12, wherein for dirtying function based on active technique an optical system as the one in active technique fog function is used, but the fields of view of emitter and receiver overlap in such a smaller volume including a portion of the optical window.

27. Detection device according to claim 12, wherein for dirtying function based on passive technique the objective used for scene monitoring is used.

28. Detection device according to claim 12, wherein optical collection components for the various functions consist of one or more matrixes of overlapping microlenses or microlenses-prisms-microlenses, whereby one or more microlenses can be present on each matrix, and for each function the optical system comprises one or more microlenses arranged on different matrixes.

29. Detection device according to claim 12, wherein the optical axis can be oriented by using micro-mirrors/micro-prisms or by axial shift or tilt of micro-lenses.

30. Detection device according to claim 12, wherein the global optical chain also comprises matrixes of microfilters, or simply optical windows partially covered with an interferential coating.

31. Detection device according to claim 1, wherein in order to insulate and adjust the diaphragm of the optical system for each function, one or more substrates of absorbing material, conveniently perforated, are used, said substrates being placed before or after microlens matrixes so as to act as aperture stop, as stray light baffle or as field stop.

32. Detection device according to claim 12, wherein the sensor means have a protection window made of glass or transparent plastic, also acting as support for optical fibers (in the arrangement with standard optical elements) and, if necessary, a prism, which optical components are inserted into holes made in said window.

33. Detection device according to claim 32, wherein the protection window made of transparent plastic coincides with the substrate onto which the microlens matrix close to the photosensitive area is laid.

34. Detection device according to claim 12, wherein it is provided for an optical insulation system between the areas dedicated to the various functions, based on a partial covering of the surface of the matrix protection window or of the microlens matrix, on the side towards the matrix, with a layer of absorbing or reflecting material, for instance by serigraphy or thermal evaporation.

35. Detection device according to claim 1, wherein the matrix is a CCD or CMOS matrix, with a different size depending on the number of performed functions and of the field of view designed for traffic monitoring and control.

36. Detection device according to claim 1, wherein the CMOS sensor has a logarithmic response so as to have an almost linear development of visibility (in meters) depending on pixel light intensity, and thus a higher resolution (in terms of gray scale) for levels of visibility above 100 m.

37. Detection device according to claim 1, wherein the CMOS sensor is a color sensor so as to strengthen the algorithm of visibility evaluation with passive technique;

RGB levels in case of fog get saturated, thus making the image less brilliant and tending to white.

38. Detection device according to claim 1, wherein the matrix is a standard or parallel architecture (pixel pre-processing) CMOS matrix.

39. Detection device according to claim 21, wherein in active fog function, beyond the optical signal filter, there is a further filtering system, based on signal acquisition together with the emitter and on the use of suitable digital filters.

40. Detection device according to claim 1, wherein visibility is evaluated by the electronic module by comparing the signals originating from active and passive technique fog functions, adding if necessary the environmental lighting signal;

evaluation takes place through such suitable algorithms as to give as output an accurate and self-assured visibility signal.

41. Detection device according to claim 1, wherein the electronic module also uses temperature and humidity signals for evaluating visibility, in a data fusion algorithm improved with respect to the previous one, and predicting, if required, fog formation and/or thinning out.

42. Detection device according to claim 1, wherein said sensor means further comprise a wireless data transmitting-receiving module for communication with other identical or lower function sensors:

each sensor receives data from the preceding sensor and transmits them to the following one, and conversely;

transmission goes on as far as a base station.

43. Detection station according to claim 1, wherein said sensor means are used at least partly for transmitting instructions-information to oncoming vehicles.