Process for determining the surface state of highways in particular, and device for carrying out this process

• US 5,962,853 A
• Filed: 10/22/1997
• Issued: 10/05/1999
• Est. Priority Date: 02/24/1995
• Status: Expired due to Fees

• Current Assignee: Institut FUER Chemo und Biosensorik Muenster EV
• Original Assignee: Institut FUER Chemo und Biosensorik Muenster EV
• Inventors: Huth-Fehre, Thomas, Kantimm, Thomas, Cammann, Karl
• Primary Examiner(s): Hannaher, Constantine
• Assistant Examiner(s): Israel, Andrew
• Application Number:
  US08/894,606
• Time in Patent Office: 713 Days
• Field of Search: 250/339.11, 250/341.8
• US Class Current: 250/339.11
• CPC Class Codes: G01N 21/55 Specular reflectivity
• CPC Class Codes: G08B 19/02 Alarm responsive to formation or anticipated formation of ice
• CPC Class Codes: G08G 1/0116 from roadside infrastructure, e.g. beacons
• CPC Class Codes: G08G 1/04 using optical or ultrasonic detectors

Abstract

There are proposed a method and a device for ascertaining the surface condition, particularly of traffic routes, as regards dryness, wetness or icing, in which the surface is irradiated by a radiation source with an infrared component, and the reflected radiation is measured simultaneously in different wavelength ranges characterizing water and ice. In this case at least four wavelength ranges are selected, permitting sufficient depth or penetration of the radiation into the surface. A first and a second wavelength range are so selected that they are influenced to a very small degree by absorption of the water molecules, and a third and fourth wavelength ranges are so selected that they are characteristic for water and ice. The influence of the background on signals measured in the third and fourth wavelength ranges is compensated for by means of the information in the signals measured in the first and second wavelength ranges. In dependence on the measured signals, therefore, a prediction can be made regarding the surface condition.

Claims

1. A method as ascertaining the surface condition, particularly of traffic routes, with a view to dryness, wetness or icing, in which the surface is irradiated by a radiation source with an infrared component, and the reflected radiation is simultaneously measured in different wavelength ranges characterising water and ice, information on the surface condition being obtained in dependence on the measured signals, wherein the reflected radiation is simultaneously measured selectively in at least four wavelength ranges lying in the area between 800 and 1250 nm, a first and a second wavelength range being so selected that they are influenced to only a small degree by an absorption of the water molecules, independently of the state of aggregation, and a third and fourth wavelength are selected so that they are characteristic for water and ice, and in that an influence of the background, caused by the depth of penetration, on the signals measured in the third and fourth wavelength ranges, is compensated for by means of the information in the signals measured in the first and second wavelength ranges.

2. A method according to claim 1, wherein the third and fourth wavelength ranges are selected between 900 and 110 nm.

3. A method according to claim 1, wherein the proportions of water and ice in the overall quantity of moisture are determined from the ratio and/or the difference in the compensated signals.

4. A method according to claim 1, wherein the overall cross-section of the radiation reflected from the surface is measured independently of locus for each wavelength range.

5. A device of ascertaining the surface condition, particularly of traffic routes, as regards dryness, wetness or icing, with a radiation source with an infrared component for irradiating the surface, an optical condenser system in the beam path in front of the surface to be tested, an optical arrangement collecting the reflected component of the electromagnetic radiation, and a wavelength-selective receiver arrangement, which receives the reflected radiation in accordance with a plurality of wavelength ranges, and an evaluation unit for evaluating the wavelength-selective signals, wherein the receiver arrangement is provided for reception of radiation in four wavelength ranges in a field between 800 and 1250 nm, a first and second wavelength range being so selected that they are influenced to only a small degree by absorption of the water molecules, independently of the state of aggregation, and a third and fourth wavelength range are so selected that they are characteristic for water and ice, and in that the evaluation device is provided in order to compensate for an influence of the background of the signals measured in the third and fourth wavelength ranges by means of the information from the signals measured in the first and second wavelength ranges.

6. A device according to claim 5, wherein the receiver arrangement has three beam-splitters for splitting the reflected radiation into four beam paths of identical locus information and four wavelength-selective filters in front of the respective receivers, which have a transmission band between 800 and 1250 nm.

7. A device according to claim 5, wherein the receiver arrangement has a spatially dispersive element in the form of at least one lattice or prism, which forms a wavelength-selective diffraction spectrum in the wavelength range between 800 and 1250 nm, and that receivers are locally associated with this dispersive element.

8. A device according to claim 5, wherein the receivers are in the form of detector arrays.

9. A device according to claim 5, wherein the device is disposed on vehicles in front of and/or behind a vehicle track.