madrid2i

Resumen

[0001] Sensor and method for detecting road conditions while a vehicle is moving, the sensor comprising a dual optical frequency comb, optical means for directing the output beam of the comb towards a verification site of the road, a photodetector and receiving optics for directing the back reflected light towards the photodetector, the photodetector being provided with electronics for obtaining the RF spectrum of the detected signal and resolving the optical spectrum of the verification region from the RF spectrum.

Reivindicaciones

1. A road condition sensor for detecting a state condition of the surface of the roadway in a specific verification region (3) ahead of a vehicle, characterized in that it comprises: - an emitting group (1) for emitting optical pulses (2), comprising: ∘ a first system to generate a first optical frequency comb with a central frequency f1 and a frequencies span of n*Δf1, being n the number of the comb lines and Δf1 the spacing between comb lines, where the spectral bandwidth of the comb covers a region of the spectrum where the refraction index is different if the verification region if in state condition or another: ∘ a second system to generate a second optical frequency comb with a central frequency f2 and a frequencies span of m*Δf2, being m the number of the comb lines and Δf2 the spacing between comb lines, where the spectral bandwidth of the second comb overlaps the spectral bandwidth of the first comb; - a receiving group (5) for a reflected signal (4) comprising: ∘ a photodetector (5.2) intended for receiving the reflected radiation (4) coming from the first and second comb after striking the verification region (3) and outputting an electrical signal S1, with a bandwidth BW; ∘ electronic means to compute the radiofrequency spectrum of signal S1. 2. The road condition sensor according to claim 1, wherein: - the difference of the frequencies of the two combs (|f2-f1|) equals the central frequency bandwidth of the receiving group (BW), - the heterodyne of first comb and second comb generate frequencies with in the bandwidth of the receiving group (BW). 3. The road condition sensor of claims 1 or 2 wherein the dual optical frequency comb is formed by two optical frequency comb generators that use the same laser diode as a source. 4. The road condition sensor of any of the previous claims wherein the optical frequency combs have a central wavelength in a region of the spectrum where the absorption properties of water and ice are different. 5. The road condition sensor of claim 4 wherein the optical frequency combs have a central wavelength in one of the ranges between 900 and 1350 nm, between 1400 and 1800 nm and between 1900 nm and 2100 nm in the near infrared. 6. A method for determining the state condition of the surface of a roadway in a specific verification region (3) ahead of a vehicle, comprising the steps of: - generating a first optical frequency comb with a central frequency f1 and a frequencies span of n*Δf1, being n the number of the comb lines and Δf1 the spacing between comb lines, where the spectral bandwidth of the comb covers a region of the spectrum where the refraction index is different if the verification region if in state condition or another; - generating a second optical frequency comb with a central frequency f2 and a frequencies span of m*Δf2, being m the number of the comb lines and Δf2 the spacing between comb lines, where the spectral bandwidth of the second comb overlaps the spectral bandwidth of the first comb; - combining the output signals of the two combs to obtain a dual comb and directing such a pulse (2) towards the verification region; - receiving a reflected signal (4) at a photodetector (5.2) after striking the verification region (3); - outputting an electrical signal S1, with a bandwidth BW, - computing the radiofrequency spectrum of signal S1, - comparing the amplitude of the line of frequency f = f2-f1 with an amplitude of reference for the pavement in the dry condition; - if f is different than the reference, then, - calculating the ratios of the amplitudes of the frequencies around the central frequency f; - assessing the road condition as "wet" if the ratio is above a threshold and as "ice" if it is below the threshold.

Índice de la ficha

En detalle

Resumen

Reivindicaciones

Etiquetas