Abstract
A method for ascertaining a solid physical state of water on a roadway surface. The method encompasses: emitting light having at least two predefined wavelengths or predefined wavelength ranges which differ from one another; receiving a signal representing an intensity of a portion of the emitted light which is scattered back by the roadway surface to an optical sensor; ascertaining a solid physical state of water on a roadway surface based on a ratio of received values for light intensities of the respective predefined wavelengths or predefined wavelength ranges within the signal; classifying the solid physical form of water on the roadway surface by reconciling absolute values of the signal with a first predefined threshold value and/or by reconciling a signal-to-noise ratio of the signal with a second predefined threshold value; and using the ascertained information regarding the solid physical state of the water in the transportation device.
Claims
1-10. (canceled)
11. A method for ascertaining a solid physical state of water on a roadway surface, comprising the following steps: emitting light of a light source of an optical sensor of a transportation device at a predefined angle onto the roadway surface, the light source being configured to emit the light having at least two predefined wavelengths or predefined wavelength ranges which differ from one another; receiving a signal of a light detector of the optical sensor, representing an intensity of a portion of the emitted light which is scattered back by the roadway surface to the optical sensor; ascertaining a solid physical state of water on a roadway surface based on a ratio of received values for light intensities of the respective predefined wavelengths or predefined wavelength ranges within the signal; classifying the solid physical form of water on the roadway surface by: (i) reconciling absolute values of the signal with a first predefined threshold value, and/or (ii) reconciling a signal-to-noise ratio of the signal with a second predefined threshold value; and using ascertained information regarding the solid physical state of the water in the transportation device.
12. The method as recited in claim 11, wherein the light source: encompasses a single light-emitting device or a plurality of light-emitting devices; and/or is a laser light source or an LED light source; and/or is embodied to emit near-infrared light whose wavelength lies in a range between 800 nm and 3000 nm.
13. The method as recited in claim 11, wherein the predefined angle of the optical sensor of the transportation device with respect to the roadway surface is an angle of between 10° and 54°.
14. The method as recited in claim 11, wherein the predefined angle of the optical sensor of the transportation device with respect to the roadway surface is an angle of between 15° and 35°.
15. The method as recited in claim 11, wherein the predefined angle of the optical sensor of the transportation device with respect to the roadway surface is an angle of 20°.
16. The method as recited in claim 11, wherein an information item regarding a current degree of deflection of a suspension system of the transportation device is taken into account upon reconciliation of the absolute values of the signal with the first predefined threshold value.
17. The method as recited in claim 11, wherein the classification of the solid physical state of water on the roadway surface is additionally carried out based on further sensors of the transportation device.
18. The method as recited in claim 11, further comprising: ascertaining a layer thickness of the water in its respective solid physical state based on the signal.
19. The method as recited in claim 11, wherein the solid physical state of water on the roadway surface is ascertained based on a machine learning method.
20. The method as recited in claim 11, further comprising: ascertaining a confidence value for the solid physical form of the water; and using the confidence value in the transportation device.
21. The method as recited in claim 11, wherein a plurality of signals of the optical sensor, which have each been received at different positions of the transportation device, are taken into account upon classification of the solid physical state of the water.
22. An apparatus for ascertaining a solid physical state of water on a roadway surface, comprising: an evaluation unit; a data input; and a data output; wherein the evaluation unit is configured to: in conjunction with the data output, emit light of a light source of an optical sensor of a transportation device at a predefined angle onto a roadway surface, the light source being configured to emit the light having at least two predefined wavelengths or predefined wavelength ranges that differ from one another; in conjunction with the data input, receive a signal of a light detector of the optical sensor representing an intensity of a portion of the emitted light which is scattered back by the roadway surface to the optical sensor; ascertain a solid physical state of water on a roadway surface based on a ratio of received values for light intensities of the respective predefined wavelengths or predefined wavelength ranges within the signal; classify the solid physical state of water on the roadway surface by: (i) reconciling absolute values of the signal with a first predefined threshold value, and/or (ii) reconciling a signal-to-noise ratio of the signal with a second predefined threshold value; and in conjunction with the data output, use the classified solid physical state of the water in the transportation device.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
[0026] Exemplifying embodiments of the present invention are described below in detail with reference to the figures.
[0027] FIG. 1 is a flow chart illustrating steps of an exemplifying embodiment of a method according to the present invention.
[0028] FIG. 2 is a schematic overview of an apparatus according to the present invention in conjunction with a means of transportation.
[0029] FIG. 3a shows a comparative example of a spectrum of a first signal and a second signal of an optical sensor of a means of transportation.
[0030] FIG. 3b shows a comparative example of a third signal and a fourth signal of an optical sensor of a means of transportation.
DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS
[0031] FIG. 1 is a flow chart illustrating steps of an exemplifying embodiment of a method according to the present invention for ascertaining a roadway state. In step 100, light of an LED light source of an optical sensor of a means of transportation (i.e., transportation device) is emitted, at a predefined angle of 20°, onto a roadway surface being traveled on by the means of transportation. The LED light source is configured to emit light having at least two predefined wavelengths or predefined wavelength ranges that differ from one another. The optical sensor has control applied to it by way of an evaluation unit according to the present invention, which here is a microcontroller. The evaluation unit according to the present invention is informatically connected for that purpose to the optical sensor via a FlexRay bus of the means of transportation. In step 200, the evaluation unit receives a signal of a light detector of the optical sensor, representing an intensity of a portion of the emitted light which was scattered back by the roadway surface to the optical sensor. The signal is received in the evaluation unit in the form of digital data and is stored by the evaluation unit in an internal memory unit of the evaluation unit. In step 300, a solid physical state of water on the roadway surface is to be ascertained by the evaluation unit on the basis of a ratio of received values for the respective predefined wavelengths or predefined wavelength ranges within the signal. In step 400, the solid physical state of the water on the roadway surface is classified by way of the evaluation unit. For that purpose, absolute values of the signal are reconciled with a first predefined threshold value stored in the memory unit. Because the absolute values of the signal are low in this exemplifying embodiment, the result of the reconciliation is that the roadway is ice-covered. In step 600, the layer thickness of the ice on the roadway surface is ascertained. In the subsequent step 700, a confidence value for a reliability of the classification of the solid physical state of the water is ascertained. In step 500 and step 800, the confidence value is combined with the result for the solid physical state of the water, and is transferred in the form of a bus signal to a control device for a highly automated driving mode. In this control device the result is then used, in consideration of the confidence value, to adapt the control function of the means of transportation.
[0032] FIG. 2 is a schematic overview of an apparatus according to the present invention in conjunction with a means of transportation 80. The apparatus according to the present invention encompasses an evaluation unit 10, which here is a microcontroller. Evaluation unit 10 is informatically connected to an external memory unit 20 and is configured to execute above-described method steps according to the present invention on the basis of a computer program. Evaluation unit 10 is furthermore connected via a data input 12 and a data output 14, via a portion of a vehicle electrical system of means of transportation 80, to an optical sensor 30 that is oriented at an angle of 20° with respect to roadway surface 70 and is disposed in the underbody region of means of transportation 80. The portion of the vehicle electrical system is implemented here on an Ethernet basis. A camera 40, which is disposed in the front region of means of transportation 80 and detects roadway surface 70, is likewise connected informatically to evaluation unit 10 via the aforesaid portion of the vehicle electrical system. Based on a signal of camera 40, evaluation unit 10 is capable of plausibilizing a roadway state to be ascertained by way of the method according to the present invention. Evaluation unit 10 is furthermore connected informatically via data output 14, via the portion of the vehicle electrical system, to a control device 50 for a highly automated driving mode. A result of the method according to the present invention, ascertained by evaluation unit 10 on the basis of the method according to the present invention, is transferred in the form of a digital signal, via data output 14, to control device 50 for the highly automated driving mode. Control device 50 for the highly automated driving mode uses the result of the method according to the present invention to adapt a current control function for means of transportation 80.
[0033] FIG. 3a shows a comparative example of a spectrum of a first signal 60 detected in broadband fashion, and a second signal 62 detected in broadband fashion, of an optical sensor of a means of transportation. First signal 60 represents a signal that is detected by the optical sensor when a roadway surface is covered with snow in such a way that the latter is present only in pores of the roadway surface, and the roadway surface is thus not completely covered with snow. Second signal 62 represents a signal that is detected by the optical sensor when the roadway surface is covered with a thin layer of ice. It is apparent from the comparative example that values of reflection factors of the first and the second signal differ sufficiently from one another that a classification of the respective signal in terms of a snow-covered or an ice-covered roadway can be carried out on the basis of the method according to the present invention.
[0034] FIG. 3b shows a comparative example of a spectrum of a third signal 64 detected in broadband fashion, and a fourth signal 66 detected in broadband fashion, of an optical sensor of a means of transportation. Third signal 64 represents a signal that is detected by the optical sensor when a roadway surface is completely covered with a continuous layer of snow. Fourth signal 66 represents a signal that is detected by the optical sensor when the roadway surface is covered with a thick layer of ice. It is apparent from the comparative example that values of reflection factors of the third and the fourth signal differ from one another sufficiently that a classification of the respective signal in terms of a snow-covered or an ice-covered roadway can be carried out on the basis of the method according to the present invention.
