Fog detector for vehicles with special shaped lens

Abstract

The invention relates to a fog detector for a vehicle having a specially shaped lens, comprising a light emitter (1) configured to emit at least one light pulse, a first optical element (2) configured to guide light of the at least one light pulse along a first optical path, a second optical element (4) configured to guide scattered light of the at least one light pulse along a second optical path to a focal point of a light receiver (3) of the fog detector, wherein the focal point is spatially offset from an axis extending along the first optical path, the first optical element (2) and the second optical element (4) being arranged and configured such that the first and second optical paths at least partially overlap each other, and the first optical element (2) and the second optical element (4) being arranged and configured such that the light emitter (1) and the light receiver (3) are operable on a common optical axis. The invention also relates to a method for fog detection and to a driving support system comprising the fog detector. Furthermore, the invention relates to a vehicle comprising the driving support system. Moreover, the invention relates to a computer program, to a data carrier signal and to a computer readable medium.

Description

Technical Field

[0001] This invention relates to a fog detector with a specially shaped lens. It also relates to a driving support system incorporating the fog detector.

[0002] Furthermore, the present invention relates to a vehicle including the driving support system or the fog detector.

[0003] Furthermore, the present invention relates to a method for fog detection. Additionally, the present invention relates to a computer program comprising instructions that, when executed by a computer, cause the computer to perform the steps of the method.

[0004] Furthermore, this invention relates to data carrier signals transmitted by computer programs.

[0005] Furthermore, the present invention relates to a computer-readable medium including instructions that, when executed by a computer, cause the computer to perform the steps of the method. Background Technology

[0006] According to existing techniques, fog detection is performed by a camera detecting optical blur caused by fog, and then using specialized software to identify the presence of fog. Some vision systems are also equipped with an illumination source. See US 6,946,639 B2 for reference. The illumination source is used to detect backscattering from that specific light source. One drawback is that image processing requires high computational power.

[0007] LiDAR can also be used. "LIDAR" is an abbreviation for "light detection and ranging." It's a radar-related method used for measuring optical distance and velocity, as well as for long-range measurements of atmospheric parameters. LiDAR systems for atmospheric measurements emit laser pulses and detect the backscattered light from the atmosphere. The distance to the scattering point is calculated from the light's propagation time. Clouds and airborne dust particles, or aerosols, scatter the laser light, making high-resolution detection and distance measurement of cloud and aerosol layers possible. Using more sophisticated systems, atmospheric state parameters and the concentration of atmospheric trace gases can be determined. For example, LiDAR instruments can also be used to monitor emissions from factory chimneys to ensure compliance with prescribed limits.

[0008] Depending on the wavelength of the laser used, LIDAR systems are sensitive to backscattering from molecules or particles. Furthermore, the intensity of backscattering at a given wavelength depends on particle size and concentration. By using LIDAR systems employing multiple wavelengths, the precise size distribution of atmospheric particles can be determined.

[0009] One drawback of using LIDAR is that it requires high computing power to distinguish between fog and objects.

[0010] In addition, some systems, such as the one described in US 2009 / 0138210 A1, transmit a collimated beam and the receiving section collects the backscattered light. This method is more inexpensive. However, misalignment between the transmitter and receiver makes the method complex to implement in certain weather conditions when light is backscattered from a distance, such as from too far away or too close to a vehicle. In this case, the backscattered light cannot be imaged by the receiver. Another drawback is that the detection of optical phase shift requires a complex electronic system.

[0011] US 6,495,815 B1 relates to a system for automatically detecting moisture on a vehicle windshield, comprising an optical system for imaging a portion of the windshield onto an image array sensor, such as a CMOS active pixel sensor. The voltage of each pixel, representing an illuminance level, is converted into a corresponding grayscale value by an analog-to-digital converter. The grayscale values ​​corresponding to the image are stored in memory. The spatial frequency components of the grayscale values ​​are analyzed to determine the amount of rainfall present, so as to provide a control signal based on the amount of moisture present to control the operation of the vehicle's windshield wipers. The system is also adapted to detect the level of fog both inside and outside the windshield. By providing a system for automatically detecting the presence of fog inside and outside the windshield, the severe performance limitations of known automatic rain sensors are eliminated.

[0012] US 2005 / 253070 A1 relates to a sensor for detecting a fog-like medium, comprising at least two transmitters and at least one receiver, wherein the transmitter axis and receiver axis intersect at two different locations. The sensor of this invention also includes an evaluation unit that detects the medium when the receiver receives signals emitted by the two transmitters. Summary of the Invention

[0013] The purpose of this invention is to provide an improved, and particularly more reliable, fog detection method, driving support system, fog detector, vehicle, computer program, data carrier signal, and computer-readable medium.

[0014] This objective is achieved through the independent claims. Advantageous embodiments are given in the dependent claims.

[0015] In particular, the present invention provides a fog detector for a vehicle with a specially shaped lens, comprising: a light emitter configured to emit at least one light pulse; a first optical element configured to guide the light of the at least one light pulse along a first optical path; and a second optical element configured to guide the scattered light of the at least one light pulse along the second optical path to a focal point of a light receiver of the fog detector, wherein the focal point is spatially offset from an axis extending along the first optical path; the first and second optical elements are arranged and configured such that the first and second optical paths at least partially overlap each other, and the first and second optical elements are arranged and configured such that the light emitter and the light receiver are operable on a common optical axis.

[0016] The present invention also relates to a method for detecting fog, comprising method steps including any features of the fog detector according to the present invention. Preferably, the final step of the method of the present invention is performed in a vehicle. The present invention also relates to a driving support system including a fog detector.

[0017] Driving support systems may include automatic or semi-automatic driving support systems for supporting corresponding automatic or semi-automatic vehicles, or driver assistance systems for supporting vehicle drivers in different driving situations.

[0018] Fog detectors can be integrated into other sensing systems in a vehicle. For example, they can complement existing products such as rain sensors. Preferably, the fog detector is designed as an infrared sensor (IR sensor). Particularly preferred is that the detector uses radiation with wavelengths ranging from ≥600nm to ≤1500nm, and more preferably from ≥800nm ​​to ≤1200nm.

[0019] The present invention also provides a vehicle including a driving support system or a fog detector. Preferably, the vehicle is an autonomous vehicle driven by a driver.

[0020] The present invention also provides a computer program comprising instructions that, when executed by a computer, cause the computer to perform the steps of the method. A computer program is a collection of instructions for performing a specific task designed to solve a particular class of problems. The instructions of the program are designed to be executed by a computer, and require the computer to be capable of executing the program to make it run.

[0021] The present invention also provides a data carrier signal for computer program transmission.

[0022] The present invention also provides a computer-readable medium including instructions that, when executed by a computer, cause the computer to perform the steps of the method.

[0023] The principle of this invention is to combine the two optical elements of the transmitter and receiver to increase the fog detection range by merging the aerial optical paths of the received backscattered light. Furthermore, the idea behind this invention is the design of the optical element, which preferably allows the transmitter and receiver of the fog sensor to be combined on a single optical axis. This eliminates the drawbacks of misalignment. It is also an inexpensive solution, requiring only a single molded optical element.

[0024] According to a modified embodiment of the invention, the optical receiver is configured to generate at least one electronic noise signal based on the received scattered light. According to a modified embodiment of the invention, the fog detector includes a noise analyzer configured to analyze the form of at least one electronic noise signal. This method of signal analysis is readily implemented.

[0025] According to a modified embodiment of the invention, the first and second optical elements are constructed as a single piece. This allows the two optical elements to be aligned during manufacturing. It also reduces the workload in subsequent production of the fog detector.

[0026] According to a modified embodiment of the present invention, the first optical path is defined to correspond to the central optical path of the light emitter, and the second optical path is off-center relative to the optical path of the light emitter. For example, the two components can also be arranged in such a way that the two optical paths are arranged in complete opposite directions.

[0027] According to a modified embodiment of the invention, the first optical element and the second optical element are configured and arranged such that they have a common optical axis.

[0028] According to a modified embodiment of the invention, the first optical element comprises a collimating lens, and the second optical element comprises a focusing lens. In other words, the transmitter optical element must best collimate the light in order to allow the light to travel further with the highest optical density. Such an element can be designed as a conventional thick lens.

[0029] According to a modified embodiment of the invention, the first or second optical element comprises a Fresnel lens and / or a diffraction element, preferably a diffraction grating. Alternatively or additionally, one of the optical elements may be a holographic element. For example, the central portion of the optical element (preferably included by the first optical element) may function as a Fresnel lens, while the surrounding area (preferably included by the second optical element) is designed as a Fresnel lens integrated with a blazed grating.

[0030] According to a modified embodiment of the invention, the second optical element is specified to include a prism-shaped lens portion. This is a simple optical component, for example, in which a model for calculating the beam cross-section is available.

[0031] According to a modified embodiment of the invention, the first and / or second optical elements are arranged and configured such that an off-center light receiver receives focused light backscattered by a target placed in the far field. This is an easily implemented and cost-effective structure.

[0032] According to a modified embodiment of the invention, the light emitter and the light receiver are configured and / or arranged separately from each other. This allows the fog detector to adapt to various needs and conditions.

[0033] According to a modified embodiment of the invention, the first and / or second optical elements are specified to at least partially comprise a design constructed according to a freeform optical design. Freeform optics involve optical designs having at least one freeform surface, which, according to ISO standard 17450-1:2011, has no translational or rotational symmetry about an axis perpendicular to the average plane. The integration of freeform optical system components offers significant degrees of freedom. These additional degrees of freedom bring numerous potential advantages, including system miniaturization, reduced component count, and even entirely new optical functions, which will have a profound impact on the optics industry.

[0034] These and other aspects of the invention will become apparent and will be elucidated with reference to the embodiments described below. The various features disclosed in the embodiments may constitute aspects of the invention individually or in combination. Features of different embodiments may be carried over from one embodiment to another. Attached Figure Description

[0035] In the attached diagram:

[0036] Figure 1 A flowchart of the method according to the present invention is shown.

[0037] Figure 2 A schematic diagram of an embodiment of the optical element arrangement according to the present invention is shown.

[0038] Figure 3 Another schematic diagram of an embodiment of the optical element arrangement according to the present invention is shown.

[0039] Figure 4 A schematic diagram of a first embodiment of the second optical element is shown.

[0040] Figure 5 A schematic diagram of a second embodiment of the second optical element is shown.

[0041] Figure 6 Another schematic diagram of a second embodiment of the second optical element is shown.

[0042] Figure 7 Another schematic diagram of a second embodiment of the second optical element is shown.

[0043] Figure 8 A schematic diagram of an embodiment of the first optical element is shown. Detailed Implementation

[0044] Figure 1 A flowchart of the method according to the present invention is shown.

[0045] This method is applicable to fog detection in vehicles and is performed using a fog detector with a specially shaped lens and a vehicle-integrated driving support system for performing at least one step of the method.

[0046] According to step "100", the method includes emitting at least one light pulse by the light emitter 1 of the fog detector, and guiding the light of the at least one light pulse along a first optical path via a first optical element 2.

[0047] According to step "200", the method includes guiding the scattered light of at least one light pulse along a second optical path via a second optical element 4 to the focal point of the light receiver 3 of the fog detector. The focal point is spatially offset from the axis extending along the first optical path.

[0048] The first optical element 2 and the second optical element 4 are arranged and configured such that the first and second optical paths at least partially overlap each other, and the first optical element 2 and the second optical element 4 are arranged and configured such that the light emitter 1 and the light receiver 3 can operate on a common optical axis.

[0049] According to step "300", the method includes generating at least one electronic noise signal by the optical receiver 3 based on the received scattered light. According to step "400", the method further includes analyzing the form of the at least one electronic noise signal by a noise analyzer.

[0050] exist Figure 2 The diagram shows a schematic representation of the arrangement of the first optical element 2 and the second optical element 4. The first optical element 2 and the second optical element 4 are manufactured as single components. Figure 3 The image shows another view of the setup. The principle is to combine the two optical elements of the transmitter and receiver in order to increase the fog detection range by merging the in-air optical paths of the emitted light from the received backscattered light.

[0051] exist Figure 4 The image shows a first embodiment of the second optical element 4. The second optical element 4 includes a focusing lens 7 and a prism-shaped portion 8. The receiver design should be very simple, as it concerns focusing backscattered light. In other words, the focal point of the light receiver 3 is off-center to leave room for both the light emitter 1 and the light receiver 3. To achieve this, a prism-shaped portion 8 is added to the back of the lens.

[0052] exist Figure 5 The image shows a second embodiment of the second optical element 4. According to this embodiment, besides regarding... Figure 4 In addition to the portions described in the embodiments, the second optical element 4 includes portions constructed using freeform surface optics. Figure 6 and Figure 7 In the middle, it is described according to Figure 5 Other views of optical element 4. Figure 6 A front view of the second optical element 4 is shown. Figure 7 A rear view of the second optical element 4 is shown.

[0053] exist Figure 8 The image shows a possible embodiment of the first optical element 2. According to this embodiment, the first optical element 2 is a collimating lens 6. The emitter optics must preferably collimate the light to allow the light to travel further with the highest optical density. Such an element can be designed as a conventional thick lens.

[0054] The optical arrangement described above can be used in fog detection systems that can be implemented in any transparent part of the vehicle body, such as headlights or windshields. Furthermore, it can complement existing products such as rain sensors.

[0055] The analysis of optical signals can be accomplished by measuring their intensity or by performing time-of-flight measurements. In both cases, the analysis is based on optical noise, which is backscattered into the surrounding portion of the optical element. An increase in optical noise will indicate an increase in backscattered light. By analyzing optical noise in the intensity and / or time domains, the presence of fog can be identified and distinguished from optical bursts produced by a final object that may have hard physical properties.

[0056] List of reference numerals

[0057] 1. Light emitter

[0058] 2 First optical element

[0059] 3. Optical receiver

[0060] 4 Second optical element

[0061] 6. Collimating lens

[0062] 7. Focusing lens

[0063] 8. Prism-shaped lens component

[0064] 100 Light, guided by a first optical element along a first optical path, consists of at least one light pulse.

[0065] 200 The scattered light of at least one light pulse is guided along the second optical path by a second optical element to the focal point of the light receiver of the fog detector, the focal point being spatially offset from the axis extending along the first optical path.

[0066] 300 The optical receiver generates at least one electronic noise signal based on the received scattered light.

[0067] 400 The form of at least one electronic noise signal is analyzed by a noise analyzer.

Claims

1. A fog detector for a vehicle, having a specially shaped lens, the fog detector comprising: An optical transmitter (1) is configured to emit at least one optical pulse; The first optical element (2) is configured to guide the light of the at least one optical pulse along the first optical path; The second optical element (4) is configured to guide the scattered light of the at least one light pulse along the second optical path to the focal point of the light receiver (3) of the fog detector, wherein the focal point is spatially offset from the axis extending along the first optical path; The first optical element (2) and the second optical element (4) are arranged and configured such that the first optical path and the second optical path at least partially overlap each other, and The first optical element (2) and the second optical element (4) are arranged and configured such that the light emitter (1) and the light receiver (3) can operate on a common optical axis. The first optical element (2) and the second optical element (4) are constructed as a single unit. The first optical path corresponds to the central optical path of the light emitter (1). The first optical element (2) and the second optical element (4) are constructed and arranged such that the first optical element and the second optical element have a common optical axis. The first optical element (2) includes a collimating lens (6). The second optical element (4) includes a focusing lens (7) and a prism-shaped lens portion (8). The focusing lens (7) is away from the light receiver (3), and the prism-shaped lens portion (8) is close to the light receiver (3). The focus of the second optical path of the light receiver (3) through the prism-shaped lens portion (8) deviates from the first optical path of the light emitter (1).

2. The fog detector according to claim 1, wherein, The optical receiver (3) is configured to generate at least one electronic noise signal based on the received scattered light.

3. The fog detector according to claim 1 or 2, comprising a noise analyzer configured to analyze the form of the at least one electronic noise signal.

4. The fog detector according to claim 1 or 2, wherein, The second optical path is off-center relative to the optical path of the light emitter (1).

5. The fog detector according to claim 1 or 2, wherein, The first optical element (2) and / or the second optical element (4) are arranged and configured such that the eccentric light receiver (3) receives focused light backscattered by a target located in the far field.

6. The fog detector according to claim 1 or 2, wherein, The light emitter (1) and the light receiver (3) are constructed and / or arranged separately from each other.

7. The fog detector according to claim 1 or 2, wherein, The first optical element (2) and / or the second optical element (4) at least partially comprise a design constructed according to a freeform surface optical design.

8. A driving support system comprising a fog detector according to any one of claims 1 to 7.

9. A vehicle comprising a driving support system according to claim 8 or a fog detector according to any one of claims 1 to 7.

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