Classifications

• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
  • G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
  • G01N21/55—Specular reflectivity
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
  • G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
  • G01N21/47—Scattering, i.e. diffuse reflection
  • G01N21/4738—Diffuse reflection, e.g. also for testing fluids, fibrous materials
  • G01N21/474—Details of optical heads therefor, e.g. using optical fibres
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
  • G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
  • G01N21/55—Specular reflectivity
  • G01N2021/556—Measuring separately scattering and specular

Definitions

• the present description relates to sensors for non-contact determination of the road surface under a motor vehicle.
• the present description relates to optical surface sensors for detecting different road surfaces such as asphalt or concrete, as well as for detecting the state thereof, in particular for detecting dry, wet, icy or snow-covered road surfaces.
• optical surface sensors are based essentially on two basic principles.
• surface sensors are known which emit light onto the road surface and measure the diffusely reflected light and the specularly reflected light on the road surface.
• Sensors are based on the effect that the proportion of diffusely reflected light increases with increasing brightness of the road surface.
• bright such as snow-covered roads of dark asphalt can be
• the present invention is therefore based on the object to provide an improved sensor for determining the type and condition of a road, which is space-saving and offers a high recognition quality.
• the object is achieved by a sensor for detecting a condition of a road, in particular the surface of a roadway for a motor vehicle according to claim 1.
• the condition of the roadway can be a state of
• Road surface such as wet, dry, icy or snow covered or include a combination thereof.
• the nature of the roadway may also include the type of roadway or information about surface road surface roughness, such as asphalt, concrete, split or gravel, or a combination thereof.
• the sensor comprises at least one light source unit, a first detector for detecting diffusely reflected light and a second detector for detecting reflected light.
• the reflected light detected at the second detector may include specular reflected light and diffused reflected light.
• At least two polarizers provided, wherein a first polarizer is associated with a first polarization direction of the first detector.
• Light source unit is a Lichtierinpolarisator and / or the second detector is associated with a second polarizer whose polarization directions are aligned substantially perpendicular to the first polarization direction of the first polarizer.
• the diffuse and specularly reflected light on the road surface is focused by means of a common focusing device with an optical axis and split by a beam splitter onto the first detector and onto the second detector.
• the emitter axis is at least partially superimposed with the optical axis of the focusing device.
• the arrangement of the emitter axis with the optical axis of the focusing device at least partially superimposed makes it possible to substantially superimpose the emitted light beam and the light reflected from the road surface.
• Lichtierinpolarisator be arranged on or on the optical axis of the focusing device. Further, the specularly reflected light and the diffused reflected light are collected by the same focusing means. As a result, the sensor can be made compact and space-saving. All essential components can be integrated in a single housing, which allows a simple, compact and thus cost-effective installation in the vehicle.
• the optical axis of the light source unit may be or defined by the optical axis of an emitter lens disposed in front of the light source unit. It is not necessary that the one or more light sources of the
• Light source unit are arranged on the optical axis. Rather, multiple light sources can emit light of different wavelengths be arranged side by side in the vicinity of or around the optical axis of the light source unit in the light source unit.
• the direction of the reflected light in particular the specularly reflected light and the diffusely reflected light reaching the focusing means, is approximately 180 ° in relation to the direction of the emitted light beam, e.g. inclined at an angle in the range of about 170 ° to 190 °, i. You are in
• the focusing device may comprise a collecting optics.
• the collecting optics may have dimensions, in particular a diameter, which is greater than the dimensions of the light source unit and / or the diameter of the emitter lens.
• the focusing means may comprise a condenser lens and / or other optical elements known to those skilled in the art.
• the light source unit may be arranged in front of or behind the focusing device in the light beam, that is, the light source unit may be arranged with respect to the
• Focusing arrangement on the same side as the beam splitter, or be arranged on the opposite side of the beam splitter.
• the light source unit can also be arranged at least partially in the focusing device.
• Focusing device may have a receptacle or opening which receives the light source unit and / or the emitter optics associated with the light source unit.
• the opening in the focusing device can also be designed to transmit light emitted by the light source unit.
• the opening may be made substantially on the optical axis of the focusing device.
• the opening may be designed as a bore, in particular as a through hole.
• the light source unit is on the same side of the
• Focusing device such as the beam splitter, and the light source unit is protected by the focusing device.
• the emitter optics can be adapted accordingly.
• the focusing device may also have a parabolic mirror or another
• the beam splitter can be arranged in the beam path after the parabolic mirror and in front of the focal point of the parabolic mirror.
• a light source polarizer may be arranged in front of the light source unit, which polarizes the light emitted by the at least one light source in a predetermined direction.
• the light source unit can also be designed to emit polarized light.
• At least two polarizers or polarization filters are provided, of which a first polarizer is arranged on the first detector such that it transmits only light waves in the first polarization direction to the first
• a light source polarizer is provided on the light source unit, its polarization direction is substantially perpendicular to the first polarization direction of the first detector and the light emitted by the light source unit is polarized in a direction substantially perpendicular to the first polarization direction of the first detector, such that the first Detector polarized, specularly reflected light
• a second polarizer is associated with the second detector whose polarization direction is oriented substantially perpendicular to the first polarization direction of the first polarization filter.
• the second polarizing filter may alternatively or in addition to the
• Light source polarizer can be used. It can also be provided to generate already polarized light in the light source unit.
• wavelengths which are particularly well absorbed by ice or water, For example, ice or water may be detected on the roadway when the reflected light of these particular wavelengths is compared to a reference wavelength. It is thus possible to implement the principles of spectral analysis and diffuse and specular reflection in a single device or housing. That's what the light source units with all the light sources are all about
• the first and the second detector space-saving housed in a housing, which also simplifies installation and maintenance. It can emit light in at least three different wavelengths
• the light source unit may for this purpose comprise a plurality of light sources.
• the light source unit can be designed to emit infrared light of the wavelengths 1300 nm, 1460 nm and 1550 nm.
• wavelength 1460 nm While light of wavelength 1460 nm is particularly well absorbed by water, light of wavelength 1550 nm is well absorbed by ice. Light in the range of about 1300 nm can then be used as the reference wavelength. However, other wavelengths may be used. In particular, as a reference wavelength, any other wavelength can be used, which is not significantly absorbed by neither ice nor water. As a water-sensitive wavelength, any other wavelength can be used, which is absorbed in water increased. In the same way, each wave length can be chosen as the pseudo-wavelength, which is absorbed in ice. Other interesting wavelengths include e.g. 1 190, 1040, 970, 880 and 810 nm in the infrared range, as well as the visible wavelengths 625, 530 and 470 nm.
• the light source unit may be configured to emit light of exactly three different wavelengths.
• the light source unit can have three light sources, one light source for each wavelength. There are only the three light sources, one light source for each wavelength. There are only the three light sources, one light source for each wavelength. There are only the three light sources, one light source for each wavelength. There are only the three light sources, one light source for each wavelength. There are only the three light sources, one light source for each wavelength. There are only the three light sources, one light source for each wavelength.
• Wavelengths are used to detect both spectral and specular / diffuse reflected light to detect both the road condition and the type of roadway.
• Each of the light sources can be controlled individually and switched on and off independently of the other or be adjustable in intensity.
• more than the above two or three different wavelengths may be used.
• the 625 nm wavelength may also be used in addition to measuring diffuse and specularly reflected light.
• the modulation of the intensity or amplitude can be done by switching on and off all or individual light sources of the light source unit.
• the modulation of the intensity or the switching on and off can be carried out separately for each wavelength of the light source unit or for each light source of the light source unit. For example, modulating the intensity or turning it on and off for each wavelength at the same frequency, however, may be
• the light of different wavelengths is transmitted offset in time or sequentially.
• Wavelength detected As a result, a spectral analysis or splitting of the incident light at the detectors can be avoided.
• Mixed forms of different modulation techniques are also applicable, in particular frequency and amplitude modulated optical signal trains with or without interruptions.
• the present invention therefore also makes it possible to use simple detectors as the first or second detector.
• photodiodes can be used.
• the first detector and the second detector may each comprise one or more photodiodes.
• At least the first detector may be configured to detect light of all wavelengths emitted by the light source unit.
• the detector may also alternatively or additionally comprise an opto-electrical chip (e.g., CCD) or other optical pickup device.
• CCD opto-electrical chip
• the first and second detectors can be used to detect or detect specularly reflected and diffusely reflected light.
• at least one of the first and the second detector can also be used for the spectral determination. At least this detector is then designed to detect light of several wavelengths.
• the sensor has exactly the first detector and the second detector and no further detectors are provided.
• the sensor may be configured to be placed at a distance of 10 cm to 100 cm from the road surface on a vehicle or stationary.
• the emitter optics associated with the light source unit may be the
• Focusing device be designed so that diffusely and specularly reflected light in the first detector and the second detector is detected at a located at a distance of 10 cm to 100 cm from the sensor surface road surface. Due to the wide distance range, the sensor can be easily attached to different vehicles. The attachment is thus also in the
• the sensor may also include an evaluation device for evaluating or processing data determined by means of the first detector and at least by means of the second detector.
• the evaluation device may be disposed within the housing or integrated into the housing. This results in a particularly compact design and easy installation of the sensor.
• the evaluation device can also be provided as a separate element outside the sensor and be connected to the sensor, for example via a cable connection or a wireless connection.
• the evaluation device may also include a control device for the light sources of the light source unit.
• FIG. 1 shows an example of a sensor for detecting a road condition with a light source arranged behind a convergent lens
• FIG. 2 shows a sensor with a light source arranged in a bore of a converging lens
• FIG. 3 shows a sensor with a light source arranged in front of the converging lens
• FIG. 4 shows a sensor with parabolic mirror
• FIG. 5 shows by way of example how a sensor can be arranged on a vehicle.
• FIG. 1 schematically shows a first example of a structure of a sensor 102 for detecting the condition, in particular the nature and condition of a roadway 1, in particular the surface 1 a of the roadway 1.
• the sensor 102 is designed for attachment to a motor vehicle.
• the sensor 102 shown in FIG. 1 comprises a focusing device in the form of a collecting optical system, which focuses light 16 reflected by a roadway 1.
• the collection optics is exemplified as a single converging lens 160th
• the collection optics may include additional lenses and / or other optical elements.
• the reflected light 16 may include specularly reflected light and / or diffused reflected light.
• the converging lens 160 has an optical axis A which may be oriented substantially perpendicular to the roadway 1 when the sensor 102 is mounted on a vehicle. The sensor 102 is oriented so that the emitted light beam 1 1 falls approximately perpendicular to the lane 1 and the road surface 1 a.
• a first detector 122 is arranged, which comprises, for example, one or more photodiodes not shown. Further, in the light beam of the reflected light 16 between the condenser lens 160 and the focal point or focus 161 of FIG.
• Condenser lens 160 a beam splitter 150, which is adapted to pass a portion of the light collected in the condenser lens 160 and focused on the focal point 161 and reflect the other part at an angle of, for example, approximately 90 ° along a reflection axis D.
• the reflected light 16 is then focused depending on the arrangement of the beam splitter 150 to a second focal point 151 on the reflection axis D outside the optical axis A.
• the position of the reflection axis D is determined by the arrangement and orientation of the beam splitter 150 and may be other than the angle of 90 ° shown in FIG.
• a second detector 132 may be arranged.
• the first detector 122 may be associated with a first polarization filter 124 and / or the second detector 132 may be associated with a second polarization filter 134.
• a first polarization filter 124 is arranged on the optical axis A only at the first detector 122 such that light aligned in the first polarization direction of the first polarization filter 124 is incident on the first detector 122.
• it can optionally be provided to arrange a second polarization filter 134 or another filter alternatively or additionally in front of the second detector 132.
• the first detector 122 and the second detector 132 may comprise identically constructed photodiodes or may be constructed differently, for example with
• first polarization filter 124 or the second polarization filter 134 can also be assigned to the first detector 122 and / or the second detector 132.
• color filters can be used which only light specific wavelengths or certain
• the beam splitter 150 may be designed as a dichroic mirror and reflect a certain wavelength range while another
• Wavelength range is transmitted or transmitted.
• the sensor 102 further comprises a light source unit 1 12, which comprises one or more light emitting diodes (LED), not shown, laser diodes or other suitable light sources or a combination thereof.
• the light source unit 1 12 may be configured to light one or more wavelengths or
• the light source unit 1 12 is associated with a Lichtierinpolarisationsfilter 1 14 and emitter optics, so that light emitted from the light source unit 1 12 light from the Lichtierinpolarisationsfilter 1 14 polarized and emitter optics to form an emitted light beam 1 1.
• the emitter optics is exemplified as a single emitter lens 1 16. However, the emitter optic may include additional lenses and / or other optical elements.
• the light source 1 12, the polarizing filter 1 14 and the emitter lens 1 16 are arranged on the optical axis A in the example shown. However, it is mainly important that the emitter optic 1 16 is arranged and designed so that the emitted light beam 1 1 is emitted substantially along the optical axis A or is superimposed thereon.
• Light beam 1 1 is thus first polarized in the light source polarizing filter 1 14 in a predetermined direction and then through the emitter lens 1 16 and then through the converging lens 160 on the lane 1 and
• the combination of the emitter lens 1 16 and the converging lens 160 can be adjusted so that a predetermined area is illuminated on the roadway 1.
• the polarization direction of the light source polarizing filter 1 14 can in
• the second detector 132 has no polarization filter and detects both specular and diffuse reflected light.
• a second polarizing filter 134 may optionally be provided, which may be added to the
• Polarization direction of the Lichtménpolarisators 1 14 is aligned in parallel, so that with the second detector 132 mainly specularly reflected light can be detected.
• the sensor 102 also has an evaluation device 50 with which the data detected or determined by the first detector 122 and the second detector 132 are processed.
• the evaluation device 50 may be connected to the first detector 122 and the second detector 132 via a cable or a wireless connection.
• the evaluation device can also be a controller for the
• Light source unit 121 include or be connected to a controller.
• the evaluation unit 50 and / or the control can be arranged on or in the housing 4 or integrated into the housing 104, as illustrated with reference to FIGS. 1 and 3.
• the evaluation device 50 can also be arranged outside the housing 104, as shown in FIG. 2, and can be located, for example, at a different location in the vehicle 60.
• the condenser lens 162 may also have an opening 163, for example in the form of a bore, in particular in the form of a bore
• Emitter lens 1 17 influenced light can be directed to the lane 1.
• a lens 162 with central opening 163 is shown as a converging lens 162 with opening 163 by way of example in FIG. Since the emitted light beam 1 1 not here is influenced by the converging lens 162, the emitter optics, or the emitter lens 1 17 is adjusted accordingly.
• the central bore 163 of the converging lens with bore 162 can be embodied, for example, as a circular bore centered on the optical axis A.
• the further devices such as the first detector 122, the second detector 132, the beam splitter 150 and all other elements not specifically mentioned here, can also be configured identically or identically in FIG. 1 and with reference to the example described in FIG.
• FIG. 3 shows a further exemplary embodiment of the present invention, in which the light emitter device consisting of the light source unit 12, the light source polarizer 114 and the emitter lens 117 is arranged in front of the converging lens 160 on the optical axis A of the condenser lens 160.
• the term "before” refers to the arrangement of the light emitting device 1 10 on the sensor 102 relative to the converging lens 160.
• the light emitter device consisting of the light source unit 12
• the light source polarizer 114 and the emitter lens 117 is arranged in front of the converging lens 160 on the optical axis A of the condenser lens 160.
• the term “before” refers to the arrangement of the light emitting device 1 10 on the sensor 102 relative to the converging lens 160.
• the light emitter device consisting of the light source unit 12
• the light source polarizer 114 and the emitter lens 117 is arranged in front of the converging lens 160 on the optical axis A of the
• the first detector 122 and the second detector 132 opposite side of the converging lens 160 can be dispensed with an opening in the converging lens 160.
• All other components may correspond to or be identical to those in FIG. 1 or in FIG. 2, with the person skilled in the art adjusting the focal lengths and optical properties of the converging lens 160 and the emitter lens 1 17 to the changed geometry.
• the sensor 202 has a focusing device in the form of a parabolic mirror 260, which is arranged in the rear region of a sensor housing 204.
• the parabolic mirror 260 has an optical axis B and is arranged such that the incident along the optical axis B of the road surface 1 a reflected light beam 26 on a likewise located on the optical axis B focal point 261 of
• Parabolic mirror 260 is focused. Depending on the orientation of the parabolic mirror 260, this focal point 261 of the parabolic mirror 260 may be located in the center of the incident reflected light beam 26, as shown by way of example in FIG. At the focal point 261 of the parabolic mirror 260, the first detector 222 may be arranged.
• a beam splitter 250 which may essentially correspond to the beam splitter 150 of FIGS. 1 to 3, may be arranged between the parabolic mirror 260 and the focal point of the parabolic mirror 261 or the first detector 222 and a part of the light reflected or focused by the parabolic mirror 260 into one Focusing direction approximately 90 ° along a reflection axis C to a second detector 232. The second detector 232 is then located outside the optical axis B.
• the position of the reflection axis C is determined by the arrangement and orientation of the beam splitter 250 and may be other than the 90 ° angle illustrated in FIG.
• a first polarizer or first polarization filter 224 may be associated with the first detector 222.
• a second polarizer or second polarization filter 234 may be associated with the second detector 232 (shown in dashed lines).
• the first polarizing filter 224 and the optional second polarizing filter 234 may be used for the first polarizing filter 124 and the second polarizing filter 134 of FIGS. 1 to 3, respectively
• the first polarizing filter 224 before the first Detector 222 may serve to filter out specularly reflected light so that it is detected only with the second detector 232.
• On the optical axis B is also a light emitting device consisting of a light source unit 212, a Lichtizonpolarisator 214 and a
• Emitter optics exemplified as a single emitter lens 216, arranged.
• the emitter device can be designed so that the optical axis of a
• Emitter lens 216 of the optical axis B of the parabolic mirror 260 corresponds to or at least partially superimposed therewith.
• the light emitter 210 may be disposed within a sensor housing 204.
• the functional principle corresponds to that of Figures 1 to 3, but the converging lens 160 or 162 is replaced by the parabolic mirror 260 as a focusing device, and the optical paths are adjusted accordingly.
• the described sensors 102, 202 may be operated in the visible light range, for example at a wavelength of approximately 625 nm, to measure specularly reflected light and diffusely reflected light. From the
• Ratio of the diffuse reflected light measured in the first detector to the specularly reflected light additionally measured in the second detector can be inferred on the road surface brightness and road surface roughness and thus determined whether the vehicle is on an asphalt or concrete carriageway, for example.
• the described sensors 102, 202 can also be used in the infrared range at different wavelengths.
• the first detector and / or the second detector can be used.
• infrared light of wavelength 1460 nm is absorbed particularly well by water, so that light of this wavelength is only slightly reflected back to the first detector or the second detector in the wet lane. On dry roads, this wavelength is normally reflected. Infrared light of wavelength 1550 nm, however, is well absorbed by ice.
• the reference wavelength which is not significantly absorbed by either ice or water, eg, 1300 nm, serves as a reference for evaluating the absorbance of the other two
• Wavelengths 1550 nm / 1300 nm are related to the ratio 1460 nm / 1300 nm in a known manner in order to obtain information about water and ice on the road or a dry roadway.
• the different wavelengths can be transmitted in parallel, but in particular sequentially offset in time. Thus, only light of one wavelength at a time is emitted and detected accordingly. This makes it possible to dispense with a complex spectral analysis or beam splitting.
• Roadway style and condition are closed. This results in a better and more accurate information about the actual state and the nature of the lane 1 or road surface 1 a below the vehicle 60.
• a single sensor 102 or 202 in a sensor housing 104, 204 is required, but it can also several sensors are used.
• FIG. 5 shows by way of example how the sensor 102, 202 described above with reference to FIGS. 1 to 4 can be arranged in a vehicle 60.
• the sensor 102, 202 is configured to be disposed on a vehicle 60.
• the sensor 102, 202 is arranged in front of the left front wheel 62 of the vehicle 60 in the track in the example shown.
• the sensor 102, 202 may additionally or alternatively also in front of the right front wheel and / or one or both rear wheels, for. B. the left rear wheel 64, be arranged to
• the sensor 102, 202 is arranged on the vehicle 60 in such a way that the light beam 1 1, 21 emitted by the sensor 102, 202 is essentially at right angles to the light beam Road surface 1 a hits.
• the light beam 16, 26 reflected at an angle of approximately 180 ° is then detected in the sensor 102, 202.
• the sensor 102, 202 is designed to be arranged at a height h or a distance of about 10 cm to about 1 m from the road surface 1 a, wherein the distance may be adapted to the respective application.
• the height h may be in the range of about 10 cm to 40 cm.
• the height h may be about 30 cm to about 100 cm, in particular in a range of 50 cm to 80 cm.
• the senor 102, 202 may also be disposed at any other location of a vehicle 60. Further, the sensor 02, 202 may also be configured to be retrofitted to a vehicle 60.
• the vehicle 60 may be a passenger car, a utility vehicle, or any other type of vehicle.
• the indicated wavelengths are not limited to exactly these values, but may include a wavelength range containing the indicated discrete wavelengths.

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• 2010
  • 2010-06-15 DE DE102010023856A patent/DE102010023856A1/de not_active Withdrawn
• 2011
  • 2011-04-29 WO PCT/EP2011/002141 patent/WO2011157319A1/de not_active Ceased
  • 2011-04-29 JP JP2013515742A patent/JP2013529775A/ja active Pending
  • 2011-04-29 EP EP11717503.4A patent/EP2583082B1/de active Active
  • 2011-04-29 CN CN201180029538XA patent/CN102939528A/zh active Pending

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