Lidar sensor for a vehicle with light guide elements adapted to a cover element, sensor arrangement and vehicle

Abstract

The invention relates to a lidar sensor (4) for a vehicle (1), comprising a transmitter unit for emitting a light signal, a receiver unit for receiving the light signal reflected in an environment (5) of the vehicle (1), wherein the transmitter unit and / or the receiver unit has a plurality of light guide elements (10), wherein the respective light guide elements (10) are configured to guide the emitted light signal along a light guide direction (18) during emission or to guide the reflected light signal along the light guide direction (18) during reception, wherein the light guide elements (10) are arranged next to each other, and wherein the light guide elements (10) are configured such that a surface (17) formed by their free ends (16) has a predetermined angle (β) to the light guide direction (18).

Description

[0001] The present invention relates to a lidar sensor for a vehicle. Furthermore, the present invention relates to a sensor arrangement comprising such a lidar sensor. In addition, the present invention relates to a vehicle comprising such a sensor arrangement.

[0002] Modern vehicles utilize environmental sensors in conjunction with driver assistance systems to detect the vehicle's surroundings and objects within them. This paper focuses particularly on lidar sensors, which can be used in vehicles and their assistance systems, especially in highly automated driving. Lidar sensors are optical measuring devices for distance measurement, similar to radar sensors. LIDAR is an acronym for "Light Detection and Ranging." Lidar sensors are also frequently referred to as laser scanners.

[0003] When lidar sensors are installed in vehicles, a location is typically sought that is ideal both technically and aesthetically. Factors to consider include the heat generated by the lidar sensor during operation, the mechanical connection and its accuracy, the ease of replacing the lidar sensor during servicing, and the possibility of cleaning the lidar sensor. Furthermore, installation locations are determined by functional requirements, which define the areas to be covered.

[0004] When lidar sensors are used in vehicles, it is necessary to protect them from environmental influences and damage. Lidar sensors typically have a cover glass, which in most cases represents the interface with the environment. It is necessary to clean the lidar sensor's cover glass properly to ensure its functionality. For this purpose, special cleaning units for lidar sensors are used, such as wipers, spray nozzles, and compressed air nozzles.

[0005] It is also known from the prior art to use additional cover elements for lidar sensors. However, the use of cover elements has the disadvantage of reducing the maximum range of the lidar sensor. Furthermore, the effective resolution and angular accuracy can be reduced. This is because the light signal is transmitted through the cover element during both transmission and reception. During the transition of the light signal between the lidar sensor and the cover element, some of the signal can be reflected. These optical losses and the associated reduction in the lidar sensor's maximum range can be a limitation, particularly with regard to automated driving functions.

[0006] It is also known from the prior art to arrange lidar sensors behind the vehicle's windshield. However, windshields are usually inclined towards the lidar sensor. The angle-dependent reflectivity, according to Fresnel's formulas, states that the optical losses depend on the angle of incidence.

[0007] The object of the present invention is to demonstrate a solution for how a lidar sensor, together with a cover element of the type mentioned above, can be operated more efficiently in a simple manner.

[0008] This problem is solved by the features of the independent claims. Further advantageous embodiments of the invention are specified in the dependent claims.

[0009] A lidar sensor according to the invention for a vehicle comprises a transmitter unit for emitting a light signal. The lidar sensor also comprises a receiver unit for receiving the light signal reflected in the vehicle's surroundings. The transmitter unit and / or the receiver unit of the lidar sensor have a plurality of light-guiding elements. The respective light-guiding elements are configured to guide the emitted light signal along a light-guiding direction during emission and / or to guide the reflected light signal along the light-guiding direction during reception. Furthermore, the light-guiding elements are arranged side by side. The light-guiding elements are also configured such that a surface formed by their free ends has a predetermined angle to the light-guiding direction.

[0010] The lidar sensor can be used in vehicles or in vehicle driver assistance systems. With the help of the lidar sensor, objects or obstacles in the vicinity of a vehicle can be detected, for example. The lidar sensor includes the transmitter unit, which emits the light signal or laser radiation into the vehicle's surroundings. The transmitter unit can contain a suitable light source or a laser diode. The lidar sensor can emit the light signals in such a way that different solid angles in the vehicle's vicinity can be scanned. The lidar sensor also includes the receiver unit. The receiver unit of the lidar sensor serves to receive the light signal reflected in the vicinity of the lidar sensor or the vehicle. The receiver unit can include a detector to capture the received light signal.

[0011] The transmitting unit can have multiple optical guide elements for directing the transmitted light signal. These individual optical guide elements can, for example, be designed like optical fibers. The optical guide elements can direct the light signal emitted by the light source, and the light signal can then be coupled out from the free end into the environment. The receiving unit can also have optical guide elements. In the receiving unit, the optical guide elements serve to direct the received light signal from the free end to the detector. The optical guide elements of the transmitting unit can be the same as those of the receiving unit.

[0012] The light guide elements are arranged side by side. Several light guide elements can therefore be arranged one above the other and / or one behind the other. The light signal is guided along the direction of the light guide element. This direction can correspond to the main direction of extension of the respective light guide element. The free ends of the light guide elements together form the surface. During transmission, the light signal is coupled out of this surface into the surroundings. During reception, the light signal reflected from the surroundings is coupled back into the surface.

[0013] According to the invention, the light-guiding elements are designed such that the surface formed by their free ends has a predetermined angle to the direction of light transmission. The free ends of the respective light-guiding elements can therefore be angled to the direction of light transmission, so that the desired surface is formed by the adjacent light-guiding elements. This design of the free ends of the light-guiding elements allows the surface to be of virtually any contour.

[0014] Thus, the surface or contour can be adapted to a cover element behind which the lidar sensor is located when installed on the vehicle as intended. For example, the angle of the surface can be adjusted to the inclination of the cover element. In this way, an air gap between the free ends of the light guide elements and the cover element can be avoided or kept as small as possible. Such an air gap would cause a change in the refractive index and consequently a reflection of the light signal. By adapting the surface of the light guide elements to the cover element, reflections at the transition between the light guide element and the cover element can be reduced, thereby minimizing optical losses.

[0015] In one embodiment, the angle between the surface formed by the light-guiding elements and the direction of light transmission lies within a range of 10° to 40°. When the lidar sensor is installed in the vehicle as intended, the cover element may not be perpendicular to the light-guiding direction of the lidar sensor, but rather inclined at a specific angle to the light-guiding direction. This is the case, for example, when the cover element is formed by the vehicle's windshield or a headlight cover. Depending on the vehicle manufacturer, a windshield may be inclined at an angle between 60° and 70° to the vehicle's vertical axis. If the light-guiding direction of the lidar sensor runs essentially in the longitudinal direction of the vehicle, the surface of the light-guiding elements may have an angle between 20° and 30° to the light-guiding direction.This angle differs significantly, for example, from the angles used in known APC connectors (APC: Angled Physical Connect) for optical fibers.

[0016] In another embodiment, the lidar sensor comprises an optical phased array. In particular, the transmitting unit can be designed as a one-dimensional scanner based on the operating principle of an optical phased array. With this method, multiple light beams from the laser light source or laser diode can be guided into predefined paths on the surface of the transmitting unit and their phase can be altered, for example, by applying electrical currents. These individual light signals or laser beams can then be recombined so that the different phases, when combined into a single light signal or laser beam, cause a spatial deflection of the beam. Using the optical phased array, the laser radiation can be pivoted along a direction or by a defined angle in one dimension. The laser beam can also be deflected in two dimensions using the optical phased array.The spatial directions can be panned. This can result in different resolutions for the two spatial directions. It is also possible for the transmitting unit to include a focal plane array.

[0017] The transmitting unit, or optical phased array, can be implemented using semiconductor technology or on a semiconductor chip. The optical phased array can have multiple regions from which the laser radiation can be extracted. Optical elements or lenses can be arranged at these extraction regions. The transmitting unit can therefore include corresponding optical elements through which the respective laser beams are emitted. By using an optical phased array, moving elements, such as micromirrors, can be omitted.

[0018] Another aspect of the invention relates to a sensor arrangement for a vehicle. The sensor arrangement comprises a lidar sensor according to the invention and a cover element for covering the lidar sensor. The cover element is arranged relative to the lidar sensor such that it has a predetermined angle of inclination to a light-guiding direction of the lidar sensor, wherein the angle of the surface of the light-guiding elements of the lidar sensor is adapted to the angle of inclination of the cover element. In particular, the angle of the surface formed by the free ends of the light-guiding elements can correspond to the inclination or angle of inclination of the cover element with respect to the light-guiding direction. The cover element is connected to the light-guiding elements and the output surface in such a way that there is no discontinuity in the refractive index.

[0019] The sensor assembly comprises the lidar sensor and the protective cover, which serves to protect the lidar sensor from environmental influences, contamination, and damage. The protective cover can be a cover, a pane of glass, part of a vehicle front, a headlight cover, or the like. The protective cover can be made of glass, plastic, or several different materials. The protective cover can also be formed by a window of the vehicle, particularly the windshield. The protective cover can also serve to cover other vehicle components, such as additional ambient light sensors, headlights, lighting elements, or the like. The protective cover is transparent to the light signal from the lidar sensor, especially light signals in the infrared wavelength range.

[0020] In one embodiment, the cover element has a receiving area in which the light guide elements or the free ends of the light guide elements of the lidar sensor are arranged, at least partially. For example, the cover element can have a defined area in which the surface of the light guide elements can be positioned. Alternatively, the cover element can have a recess, an opening, a bore, or the like, into which the light guide elements or their free ends can be inserted, at least partially. In this embodiment, it is particularly intended that the surface of the light guide elements is adapted to the receiving area.

[0021] In another embodiment, the light guide elements of the lidar sensor and the cover element are bonded together. For example, the light guide elements, or their free ends, and the cover element can be bonded together using an adhesive. In particular, an adhesive that is transparent to the light signal from the lidar sensor can be used to bond the light guide elements and the cover element. This bonded connection eliminates air gaps between the light guide elements and the cover element, thus reducing optical losses. The adhesive can be selected to provide the most consistent refractive index profile possible.

[0022] In an alternative embodiment, the light guide elements of the lidar sensor are formed integrally with the cover element. The light guide elements, or parts thereof, can thus be integrated into the cover element. If the lidar sensor includes an optical phased array, optical phase shifters can also be integrated into the cover element. Parts of the lidar sensor can also be incorporated into the cover element. For example, parts of the lidar sensor can be integrated into the windshield or the cover element as a so-called lidar-on-photonics chip.

[0023] The lidar sensor's light source and / or detector can be located within the cover element and / or at least partially integrated into it. The lidar sensor's control unit can be located separately. In this case, electronic data transmission can then take place between the control unit and the lidar sensor components located on and / or within the cover element. Alternatively, the light source and detector can be located within the control unit. In this case, an optical connection, for example, via fiber optics, can be provided. This optical connection allows the light signal generated by the light source and the light signal reflected in the environment to be transmitted to the detector.

[0024] As previously explained, the cover element is preferably designed as a windshield. By adjusting the free ends of the light guide elements, the surface area of ​​the light guide elements can be adapted to the angle of the windshield. However, the cover element can also be formed by part of the vehicle's front, a radiator grille, a headlight cover, a taillight cover, or the like. By adjusting the surface area formed by the light guide elements, optical losses during the transmission of the lidar sensor's light signal between the light guide elements and the cover element can be avoided.

[0025] A vehicle according to the invention comprises a sensor arrangement according to the invention. The vehicle is in particular designed as a passenger car.

[0026] The preferred embodiments and their advantages presented with reference to the lidar sensor according to the invention apply accordingly to the sensor arrangement according to the invention as well as to the vehicle according to the invention.

[0027] Further features of the invention will become apparent from the claims, the figures, and the description of the figures. The features and combinations of features mentioned above in the description, as well as the features and combinations of features mentioned below in the description of the figures and / or shown in the figures alone, can be used not only in the combinations specified, but also in other combinations or on their own, without departing from the scope of the invention.

[0028] The invention will now be explained in more detail with reference to preferred embodiments and the accompanying drawings. These show: Fig. 1 a schematic representation of a vehicle comprising a sensor array with a lidar sensor; and Fig. 2 A schematic representation of the sensor arrangement, which includes the lidar sensor and a cover element in the form of a windshield.

[0029] Fig. Figure 1 shows a schematic top view of a vehicle 1, which in this case is a passenger car. The vehicle 1 includes a sensor arrangement 2, which in turn includes a lidar sensor 4. Objects 6 in an environment 5 or the vicinity of the vehicle 1 can be detected by means of the lidar sensor 4. An object 6 in the environment 5 of the vehicle 1 is shown here as an example.

[0030] The lidar sensor 4 emits light signals or laser radiation and receives the portion of the emitted laser radiation reflected by the object 6. The lidar sensor 4 then transmits sensor data describing the reflected light signal to a control unit 3 of the lidar sensor 4. Based on this sensor data, the control unit 3 determines distance values ​​that describe the respective distances between the lidar sensor 4 and the objects 6 in the environment 5. These distance values ​​can be determined based on the travel time between the emission and reception of the sensor signal. The sensor signal can also represent a point cloud.

[0031] Furthermore, the sensor arrangement 2 includes a cover element 7 for covering the lidar sensor 4. The cover element 7 protects the lidar sensor 4 from environmental influences, and in particular from damage and contamination. In the example shown, the cover element 7 is formed by a windshield 8 of the vehicle 1. In the sensor arrangement 2, the lidar sensor 4 is also located behind this windshield 8. Alternatively, the lidar sensor 4 could, for example, be located in the front of the vehicle 1.

[0032] Fig. Figure 2 shows a schematic representation of the sensor arrangement 2. The cover element 7 of the lidar sensor 4 is formed by the windshield 8 of the vehicle 1. The windshield 8 is inclined at an angle α of 60° to the vehicle's vertical axis y. The lidar sensor 4 comprises a transmitter unit with a light source 13 for emitting the light signal or laser radiation. The lidar sensor 4 also includes a receiver unit with a detector 14 for receiving the light signal reflected in the area 5 surrounding the vehicle 1. In the example shown, the light source 13 and the detector 14 are assigned to a component 12 of the lidar sensor 4, which is located on the windshield 8 or the cover element 7.

[0033] The lidar sensor 4 further comprises a plurality of light guide elements 10, which serve to guide the light signal from the light source 13 during emission. In addition, the light guide elements 10 serve to direct the light signal reflected in the environment 5 to the detector 14. In this embodiment, an electrical data line 15 can be used for data transmission between the component 12 and the control unit 3. It is also possible for the light source 13 and the detector 14 to be integrated into the control unit 3. In this case, an optical data connection between the control unit 3 and the component 12 can be used.

[0034] The individual light guide elements 10 of the lidar sensor 4 are arranged side by side. As shown, the light guide elements 10 are arranged one above the other. Alternatively or additionally, the light guide elements 10 can be arranged one behind the other. In the light guide elements 10, the light signal is guided along a light guide direction 18 during transmission and reception. In this case, the light guide direction 18 runs essentially along a longitudinal direction x of the vehicle.

[0035] The lidar sensor 4 comprises an optical phased array 9, which has an optical phase shifter unit 11 for each of the light guide elements 10. The optical phased array 9 allows the light signals to be emitted into different solid angle regions in the vicinity 5 of the vehicle 1. When using the optical phased array 9, the component 12 can be designed as a chip, and parts of the component 12 or the entire component 12 can also be integrated into the cover element 7. The light guide elements 10 can also be embedded directly into the glass of the windshield 8.

[0036] The free ends 16 of the light-guiding elements 10 together form a surface 17. This surface 17 of the light-guiding elements 10 is inclined at an angle β to the light-guiding direction 18. This angle β is adapted to the inclination angle α of the windshield 8. Thus, there is no or only a small air gap between the surface 17 of the light-guiding elements 10 and the windshield 8. In this way, optical losses during the transmission of the light signal between the lidar sensor 4 and the cover element 7 can be avoided, and the required range of the lidar sensor 4 can be guaranteed.

[0037] In the example of Fig. 2. The light guiding elements 10 or the free ends 16 of the light guiding elements 10 are also arranged in a receiving area 19 in the cover element 7 or the windshield 8. In addition, the light guiding elements 10 are bonded to the cover element 7, for example, by means of a suitable adhesive. Reference symbol list 1 vehicle 2 Sensor arrangement 3 Control unit 4 Lidar sensors 5 Environment 6 objects 7 Cover element 8 Windscreen 9 Optical Phased Array 10 light guiding elements 11 Phase shifter element 12 components 13 Light source 14 Detector 15 data lines 16 free ending 17 area 18 Light guidance direction 19 Recording area x Vehicle longitudinal direction y Vehicle uphill direction α Angle of inclination β angle

Claims

[1] Lidar sensor (4) for a vehicle (1), comprising: - a transmitter unit for emitting a light signal, - a receiving unit for receiving the light signal reflected in an environment (5) of the vehicle (1), - wherein the transmitting unit and / or the receiving unit has a plurality of light guiding elements (10), - wherein the respective light guiding elements (10) are designed to guide the emitted light signal along a light guiding direction (18) during emission or to guide the reflected light signal along the light guiding direction (18) during reception, - wherein the light guiding elements (10) are arranged next to each other, and - wherein the light guiding elements (10) are designed such that a surface (17) formed by their free ends (16) has a predetermined angle (β) to the light guiding direction (18). [2] Lidar sensor (4) according to claim 1, characterized by, that the angle (β) between the surface (17) formed by the light guiding elements (10) and the light guiding direction (18) lies in an angular range between 10° and 40°. [3] Lidar sensor (4) according to claim 1 or 2, characterized by , that the lidar sensor (4) comprises an optical phased array (9). [4] Sensor arrangement (2) for a vehicle (1), comprising: - a lidar sensor (4) according to any one of the preceding claims, - a cover element (7) for covering the lidar sensor (4), - wherein the cover element (7) is arranged in relation to the lidar sensor (4) such that the cover element (7) has a predetermined inclination angle (α) to a light guiding direction (18) of the lidar sensor (4), and - wherein the angle (β) of the surface (17) of the light guiding elements (10) of the lidar sensor (4) is adapted to the tilt angle (α) of the cover element (7). [5] Sensor arrangement (2) according to claim 4, characterized by, that the cover element (7) has a receiving area (19) in which the light guiding elements (10) of the lidar sensor (4) are arranged at least partially. [6] Sensor arrangement (2) according to claim 4 or 5, characterized by , that the light guiding elements (10) of the lidar sensor (4) and the cover element (7) are materially bonded together. [7] Sensor arrangement (2) according to claim 4, characterized by , that the light guiding elements (10) of the lidar sensor (4) are formed in one piece with the cover element (7). [8] Sensor arrangement (2) according to any one of claims 4 to 7, characterized by , that the cover element (7) is designed as a windshield (8). [9] Vehicle (1), in particular passenger car, comprising a sensor arrangement (2) according to any one of claims 4 to 8.

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