Device for detecting a state of a translucent front element of an optical sensor for a vehicle and optical sensor

Abstract

Device (10) for detecting a state of a light-transmitting front element (3) of an optical sensor (2, 9) for a vehicle, comprising the light-transmitting front element (3) and a detector device (14) for receiving light rays (13) reflected on an outer side (7) of the light-transmitting front element (3), and optical sensor (2, 9) comprising such a device (10).

Description

The invention relates to a device for detecting a state of a light-transmissive front element of an optical sensor for a vehicle, and to an optical sensor having such a device.For optical distance measurements, in particular for use in vehicles, a scanning sensor, for example a LIDAR (light detection and ranging) sensor, is usually used, which periodically emits pulses. The pulses, in particular light pulses, are reflected by objects and the reflected pulse is detected. From the determination of the travel time of the pulses from the sensor to the object and back, the distance or the distance to the object can be deduced by means of the speed of light.For example, a LIDAR measuring system having a transmitting unit and a receiving unit is known from document DE 10 2017 222 971 A1, wherein a plurality of sensor elements of the receiving unit are arranged in macrocells and each sensor element can be individually activated and deactivated or can be activated and deactivated in groups of sensor elements.LIDAR sensors, in particular based on the focal plane array detection method, or other optoelectronic sensors for vehicles, such as motor vehicles, may suffer from severe power losses. This is attributable in particular to the contamination and / or the lack of quality and / or deterioration of the front pane (light-transmissive front element), through which the sensor detects the environment. In addition, production-related fluctuations in the material and / or surface quality of the front pane can occur. During the manufacturing process or the aging of front panes, defects or defect sites cannot be avoided, so that when the laser light is transmitted through the front pane, unwanted deflection or back reflection of the laser light takes place and thus the accuracy of the sensor is negatively influenced. Increasing contamination by dirt particles on the front screen can also have a negative influence on the accuracy of the sensor, so that the front writing must be cleaned. The assessment of the visibility and / or detection capability of optoelectronic sensors, such as LIDAR sensors, is usually very complicated, since perception-based analyses of the visibility conditions through the front writing, for example on the basis of a generated point cloud, can be very time- and computation-intensive, but also inaccurate.The object of the invention is to improve a device mentioned at the beginning structurally and / or functionally. In addition, the object of the invention is to improve an optical sensor mentioned at the beginning structurally and / or functionally.The object is achieved with a device having the features of claim 1. In addition, the object is achieved with an optical sensor having the features of claim 11.A device for detecting a state of a light transmissive front member of an optical sensor for a vehicle may include the light transmissive front member. The apparatus may comprise detector means for receiving light beams reflected at an outer side of the light transmissive front element. The light beams can be emitted or emitted by the optical sensor, for example by a transmission unit of the optical sensor. The device can be designed for noninvasive detection of the state of the light-transmissive front element.The vehicle may be a motor vehicle, such as a passenger motor vehicle, or a truck. The vehicle can furthermore be, for example, a rail vehicle, a bus, or an autonomously driving shuttle. The front element can be made of glass or plastic, for example a polymer. The front element can be a pane, such as a glass pane or a plastic pane. The front element can be a sensor front pane, in particular of the optical sensor. The light transmissive front element may have an outwardly facing surface, such as an outer surface and / or a surface (e.g., an outer surface). The light transmissive front element may have an inwardly facing surface, such as an inner surface and / or a surface (e.g., an inner surface). The outwardly facing surface, such as the outer surface and / or (e.g., exterior) surface, of the light transmissive front element may be the exterior of the light transmissive front element. The detector device can be configured to receive light beams reflected at the outwardly facing surface, such as the outer surface and / or (e.g. outer) surface, of the light-transmissive front element.The state of the light-transmissive front element may be a contamination state and / or flaw state. The state of the light transmissive front member may be a front member state such as a disc state and / or a sensor front disc state, and / or a disc contamination state. The state of the light transmissive front element may be an aging state and / or damage state of the light transmissive front element.The device can be designed for detecting a contamination and / or flaw and / or aging. The contamination and / or flaw and / or aging may be on the outwardly facing surface, such as the outer surface and / or (e.g., outer) surface, of the light transmissive front element. The detector device can be designed to receive light beams reflected at the contamination and / or defect location. The detector device can be designed to receive light rays reflected on the surface facing outwards, such as the outer surface and / or (e.g. outer) surface of the light-transmissive front element. The light beams reflected at the dirt or at the dirt particles and / or at the defect location can reflect inside the light-transmissive front element once or several times, for example at the surface pointing outwards and / or inwards, in particular before they strike the detector device.The device can have an evaluation device. The evaluation device can be designed for evaluating the light beams received from the detector device. The evaluation device can be designed to determine a degree of contamination and / or a degree of defect location and / or a visibility and / or a detection capability of the light-transmissive front element, for example based on the light beams received from the detector device and / or the evaluation thereof. The evaluation device can be configured to determine the degree of contamination and / or the degree of defect and / or the visibility and / or the detection capability of the light-transmissive front element depending on at least one received wavelength of the reflected light beams or received by the detector device. As the degree of contamination, a contamination intensity and / or a contamination material can be determined. An error location intensity and / or an error location number can be determined as the error location degree.Depending on the evaluation of the light beams received by the detector device, a control signal can be generated and / or provided. The device can be designed to generate and / or provide the control signal. The apparatus can have a control device for generating the control signal. The device can generate and / or provide one or a plurality of control signals, for example different control signals, for example for different possibilities and / or countermeasures. By means of the control signal, a corresponding countermeasure can be initiated by the device. The control signal can be for a cleaning device for cleaning the light-transmissive front element and / or for a heating device for heating / heating the light-transmissive front element and / or for initiating and / or changing a driving state of the vehicle, or can serve for controlling the latter. For example, the control signal can initiate termination of the travel in the automated driving state of the vehicle and / or the light-transmissive front element, in particular its outwardly facing surface, such as the outer surface and / or (e.g. outer surface), can be cleaned or freed of dirt particles by means of the cleaning device. The device can comprise the cleaning device and / or heating device. The cleaning device can be a liquid and / or air cleaning device. The cleaning device can have a cleaning nozzle, such as a spray nozzle. The cleaning device can comprise a liquid or gaseous cleaning medium. The cleaning medium can be applied by means of the cleaning nozzle to the light-transmissive front element, in particular to its outwardly facing surface, such as the outer surface and / or (e.g. outer) surface. The cleaning device may generate ultrasonic waves for cleaning. The heating device can have at least one heating element. The at least one heating element can be a heating wire or heating coil. The at least one heating element can be integrated in the light-transmissive front element. The heating device can have a heating fan or a warm air fan.This makes it possible for the state of the light-transmissive front element of the optical sensor for the vehicle to be able to be detected accurately and then the control signal can be correspondingly generated and / or provided depending on the respective state.The detector device can be arranged on the inwardly facing surface, such as the inner surface and / or (e.g. inner) surface, of the light-transmissive front element and / or can be effectively fastened thereto. The detector device can be arranged on the outwardly facing surface, such as the outer surface and / or (e.g. outer) surface, of the light-transmissive front element and / or can be effectively fastened thereto. The detector device can be arranged outside a receiving unit of the optical sensor, in particular outside a receiving range of the receiving unit of the optical sensor.The detector device can have one or more receiving elements, for example a two-dimensional arrangement of receiving elements, for receiving the reflected light beams. The receiving elements may be diodes such as photodiodes. The detector device can have a sensor, such as an image sensor or a camera sensor. The sensor can be formed by the one or more receiving elements. The detector device can have one or more filters, such as optical filters, wavelength filters and / or color filters.An optical sensor can have the device described above and / or below for detecting a state of a light-transmissive front element of the optical sensor. The optical sensor can be for a vehicle, such as a motor vehicle or a motor vehicle. The optical sensor can be designed for static or immovable arrangement on a vehicle. The optical sensor may include the light transmissive front element. The optical sensor can be an optoelectronic sensor.The optical sensor can have a transmission unit for transmitting light beams, such as laser beams. The optical sensor can have a receiving unit for receiving the light beams emitted by the transmitting unit. The transmitting unit and receiving unit can form a transmitting and receiving device. The receiving unit may be configured to receive the light beams emitted from the transmitting unit, reflected at an object such as a target object, and transmitted through the light transmissive front element.The transmitting unit can have one or more emitter elements, for example a two-dimensional arrangement of emitter elements, for transmitting light beams, such as laser beams. The emitter elements may be diodes, such as light emitting diodes (LEDs) and / or laser diodes. The receiving unit can have one or more receiving elements, for example a two-dimensional arrangement of receiving elements, for receiving the light beams, such as laser beams, emitted by the transmitting unit, and / or light beams reflected on an object, such as a target object, and / or transmitted through the light-transmissive front element. The receiving elements may be diodes, such as photodiodes and / or avalanche diodes, for example single photon avalanche diodes (SPAD). Single photon avalanche diodes are avalanche diodes which already trigger an avalanche effect when a single photon arrives and can thereby enable a detection of this photon. The receiving unit may alternatively comprise a silicon photomultiplier (SiPM) for receiving the light beams, or alternatively be based on CCD or CMOS chip variants.The optical sensor can have a transmission optics and / or a reception optics. The transmission optics can be or serve for the transmission unit. The reception optics can be or serve for the reception unit. The optical sensor, for example its transmission optics and / or a reception optics, can have one or more filters, such as optical filters, wavelength filters and / or color filters.The light-transmissive front element can be arranged in front of the transmitting unit and / or receiving unit. The inwardly facing surface, such as the inner surface and / or (e.g. inner) surface, of the light-transmissive front element can be a surface facing the transmitting unit and / or receiving unit. The detector device of the apparatus can be arranged outside the receiving unit of the optical sensor, in particular outside a receiving range of the receiving unit of the optical sensor. In this case, the detector device of the device can be arranged on the inwardly facing surface, such as the inner surface and / or (e.g. inner) surface, of the light-transmissive front element and / or be fastened thereto in an effective manner.The optical sensor may be a LIDAR sensor. The optical sensor or the LIDAR sensor can be embodied in a focal plane array arrangement. A focal plane array configuration can be understood to mean a two-dimensional arrangement of emitter elements of the transmitting unit and / or receiving elements of the receiving unit in a plane, in particular the focal plane of the transmitting optics and / or receiving optics. A focal plane array configuration can therefore enable a static configuration of the LIDAR sensor and / or its transmitting unit and / or receiving unit, so that it does not comprise any moving parts.In other words, the device can serve or be designed for detecting the pane contamination or pane state in an optoelectronic sensor. The visibility / detection capability of optoelectronic sensors, such as lidar sensors, can be assessed or the device can be configured for this purpose. By means of this sensor concept, the state of the sensor front window can be detected non-invasively, in particular for so-called focal plane array lidar sensors.If the optical sensor, e.g. the lidar sensor, is no longer completely performable, a countermeasure such as windshield cleaning and / or windshield heating and / or the termination of the travel in the automated driving state can be initiated accordingly.With the invention, the accuracy and operation of the optical sensor can be improved. The assessment of the visibility and / or detection capability of optoelectronic sensors, such as LIDAR sensors, can be improved and / or simplified. The assessment of the visibility / detection capability of optoelectronic sensors, such as LIDAR sensors, can be carried out without perception-based analyses on a generated point cloud. The perception-based analysis of the visibility conditions through the pane (light-transmissive front element) can therefore be omitted. Driving scenarios are not used where, for example, the range estimation of the sensor is explicitly carried out on the basis of algorithmically ascertained characteristic variables. The quality of the windshield cleanings can be improved.Exemplary embodiments of the invention are described in more detail below with reference to figures, in which: FIG. 1 schematically shows the beam path of an optical sensor with a good or clean front element; and FIG. 2 schematically shows the beam path of an optical sensor with a deteriorated or soiled front element.FIG. 1 shows the beam path 1 of an optical sensor 2 having a light-transmissive front element 3. The optical sensor 2 has a transmitting unit 4 with emitter elements and a receiving unit 5 with receiving elements. The transmitting unit 4 emits laser beams (illustrated by the arrows in FIG. 1 ) through the front element 3, which are then reflected by a target object 6. The reflected beams transmit or pass through the front element 3 and then strike the receiving unit 5.The front element 3 is designed as a sensor front window, for example made of glass or plastic, and has an outwardly facing outer surface 7 and an inwardly facing inner surface 8. The inner surface 8 is oriented or arranged towards the transmitting unit 4 and towards the receiving unit 5.The front element 3 has neither defects nor soiling on the outer surface 7, so that the light beams 1 emitted by the transmission unit 4 and beams reflected on the target object 6 can be transmitted optimally through the front element 3 and received by the reception unit 5.FIG. 2 schematically shows an optical sensor 9 with a device 10 for detecting a state of the light-transmissive front element 3 of the optical sensor 10. As a result, aberrations can arise and the accuracy of the optical sensor 2 suffers.The apparatus 10 has a detector device 14 for receiving the light beams 13 of the transmitting unit 4 reflected back on the outer side or outer surface 7 of the light-transmissive front element 3 by the flaws 11 and / or dirt particles 12. The detector device 14 has a plurality of receiving elements, in particular a two-dimensional arrangement of receiving elements, for receiving the light beams reflected back. The detector device 14 is effectively arranged outside a reception range of the receiving unit 5 and on the inner surface 8 of the light-transmissive front element 3.The apparatus 10 further comprises an evaluation device 15 which is designed, in particular, for determining a degree of contamination and / or a degree of defect location and / or a visibility and / or a detection capability of the light-transmissive front element 3, for evaluating the light beams 13 received by the detector device 14. A contamination intensity and / or a contamination material can be determinable as the degree of contamination and / or a fault location intensity and / or a fault location number can be determinable as the degree of fault location.Depending on the evaluation of the light beams received by the detector device 14, the device 10 can generate and / or provide a control signal by means of a control device 16, in particular for a cleaning device for cleaning the light-transmissive front element 7 and / or for a heating device for heating the light-transmissive front element 7 and / or for initiating and / or changing a driving state of a vehicle in which the optical sensor 9 is arranged.For the rest, reference is additionally made in particular to FIG. 1 and the associated description.Optional features of the invention are designated in particular by "can". Accordingly, there are also developments and / or exemplary embodiments of the invention which additionally or alternatively have the respective feature or the respective features.Isolated features can also be extracted from the combinations of features disclosed here, if necessary, and used in combination with other features to delimit the subject matter of the claim, resolving a structural and / or functional relationship optionally existing between the features.Reference numerals denote reference numerals1 Beam path 2 Optical sensor 3 Light-transmissive front element 4 Transmission unit 5 Reception unit 6 Target object 7 Outer surface 8 Inner surface 9 Optical sensor 10 Device 11 Flaws 12 Dirt particles 13 Back reflections 14 Detector device 15 Evaluation device 16 Control deviceReferences included in the specificationThis list of documents cited by the applicant has been produced in an automated manner and is only included for the better information of the reader. The list is not part of the German patent application or utility model application. The DPMA does not take any adhesion for any faults or omissions.Patent Literature citedDE 10 2017 222 971 A1

[0003]

Claims

Device (10) for detecting a state of a light-transmissive front element (3) of an optical sensor (2, 9) for a vehicle, having the light-transmissive front element (3) and a detector device (14) for receiving light beams (13) reflected on an outer side (7) of the light-transmissive front element (3).Device (10) according to claim 1, characterised in that the device (10) is designed for detecting a contamination (12) and / or flaw (11), in particular on an outwardly facing surface (7), such as outer surface and / or surface, of the light-transmissive front element (3).Device (10) according to at least one of the preceding claims, characterized in that the device (10) has an evaluation device (15) which is designed, in particular for determining a degree of contamination and / or degree of defect location and / or a visibility and / or detection capability of the light-transmissive front element (3), for evaluating the light beams (13) received by the detector device (14).Device (10) according to Claim 3, characterized in that, depending on at least one received wavelength of the reflected light beams (13), the degree of contamination and / or the degree of defect and / or the visibility and / or detection capability of the light-transmissive front element (3) can be determined by means of the evaluation device (15), and / or a contamination intensity and / or a contamination material can be determined as the degree of contamination, and / or a defect intensity and / or number of defects can be determined as the degree of defect.Device (10) according to at least one of the preceding claims, characterized in that the device (10) is designed for noninvasive detection of the state of the light-transmissive front element (3).Device (10) according to at least one of the preceding claims, characterized in that, depending on the evaluation of the light beams (13) received by the detector device (14), a control signal can be generated, in particular for a cleaning device for cleaning the light-transmissive front element (3) and / or for a heating device for heating the light-transmissive front element (3) and / or for introducing and / or changing a driving state of the vehicle.Device (10) according to at least one of the preceding claims, characterized in that the detector device (14) is designed to receive light beams (13) reflected on an outwardly facing surface (7), such as outer surface and / or surface, of the light-transmissive front element (3).Device (10) according to at least one of the preceding claims, characterized in that the detector device (14) is designed to receive light rays (13) reflected on dirt particles (12) present on an outwardly facing surface (7), such as outer surface and / or surface, of the light-transmissive front element (3).Device (10) according to at least one of the preceding claims, characterized in that the detector device (14) is arranged on and / or fastened to an inwardly facing surface (8), such as inner surface and / or surface, of the light-transmissive front element (3) or on an outwardly facing surface (7), such as outer surface and / or surface, of the light-transmissive front element (3).Apparatus (10) according to at least one of the preceding claims, characterized in that the detector device (14) has one or more receiving elements, in particular a two-dimensional arrangement of receiving elements, for receiving the reflected light beams (13).Optical sensor (2, 9), in particular a LIDAR sensor, for a vehicle, having a device (10) according to at least one of the preceding claims.Optical sensor (2, 9) according to Claim 11, having a transmission unit (4) for transmitting light beams, such as laser beams, and a reception unit (4) for receiving the light beams which are emitted by the transmission unit (4) and reflected on an object (6) such as target object and have passed through the light-transmissive front element (3), wherein the detector device (14) of the apparatus (10) is arranged outside a reception range of the reception unit (5).

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