Method for determining environmental information relating to a property of an object and / or a surface in the surroundings of a motor vehicle, and motor vehicle comprising a lidar device

Abstract

The invention relates to a method for determining at least one item of environmental information (24) relating to a property of at least one object (6) located in the surroundings (4) of a motor vehicle (1) and / or at least one surface (7) located in the surroundings (4), wherein laser light is generated by means of at least one lidar device (2) of the motor vehicle (1) and emitted into the surroundings (4), wherein the lidar device (2) has at least two detection units (9), each of which detects a portion (8) of the laser light that is backscattered from the object (6) and / or the surface (7) to said detection unit (9), wherein, in order to determine the environmental information (24), an interferometric phase evaluation is performed in which, using a known relative position of the detection units (9) with respect to one another, at least one item of phase information (15) is determined which relates to a phase difference between the portions (8) of the laser light backscattered to the different detection units (9), wherein the environmental information (22) is determined based on the phase information (14).

Description

[0001] Method for determining environmental information relating to a property of an object and / or a surface in an environment of a motor vehicle, and motor vehicle comprising a lidar device

[0002] DESCRIPTION:

[0003] The present invention relates to a method for determining at least one item of environmental information relating to a property of at least one object located in the environment of a motor vehicle and / or at least one surface located in the environment, wherein laser light is generated by means of at least one lidar device of the motor vehicle and emitted into the environment, wherein the lidar device has at least two detection units, by means of which a part of the laser light scattered back at the object and / or the surface to the respective detection unit is detected.

[0004] One method for detecting or determining properties or parameters relating to objects and / or surfaces in the vehicle's environment is information acquisition using Lidar. Lidar refers to a three-dimensional scanning process using laser light. The term "Lidar" is an abbreviation for "Light Detection and Ranging." The obtained results are often used in the control of autonomous vehicles and / or displayed to the driver.

[0005] Lidar devices or sensors often operate according to a scanner principle, in which the laser beam sweeps the surroundings line by line or column, obtaining information regarding the time of flight of the laser light and the distance between the vehicle and the reflective surface from the reflected laser light. This method is referred to as the time-of-flight method, abbreviated to "ToF." Another approach is the FMCW method, where FMCW is an abbreviation for Frequency Modulated Continuous Wave. This method involves modulating the frequency of the laser light, and the laser light reflected from the object and returning to the lidar device is detected. Furthermore, concepts are known in which data collected using multiple lidar sensors is evaluated, for example, from the publications DE 10 2019 107 568 A1, EP 4 141 478 A1, and US 2021 / 0 183 093 A1.

[0006] There is a need to improve the quality and scope of the data acquired using lidar. The object of the present invention is to provide an improved concept in this regard in connection with a lidar detector of a motor vehicle.

[0007] According to the invention, the object is achieved in a method of the type mentioned at the outset in that an interferometric phase evaluation is carried out to determine the ambient information, in which at least one piece of phase information is determined using a known relative position of the detection units to one another, which piece of phase information relates to a phase difference between the parts of the laser light scattered back to the various detection units, the ambient information being determined on the basis of the phase information.

[0008] The present invention is based on the idea of ​​using a previously unused source of information to determine environmental information. Thus, the emitted laser light is reflected and / or scattered by the object and / or surface, whereby the path or transit time of the portions of the laser light scattered back to the various detection units differs because the detection units are spaced apart from one another. Unless this difference corresponds to an integer multiple of the wavelength of the laser light, this results in a phase difference or phase shift between the backscattered portions of the laser light, which is detected or measured.This effect allows an analysis directed at the respective path differences of the backscattered parts of the laser light, realizing accuracies down to the sub-millimeter range and which is used according to the invention in the context of determining the environmental information.

[0009] The term phase shift refers to the difference between the phases of the backscattered parts of the laser light. The phase shift is typically a modulo value that is usually standardized with respect to the duration of a complete phase transition. It can assume values ​​between 0 and 1, between 0 and 2TT or between 0 and 360°. A prerequisite with regard to the method according to the invention is that coherence can be assumed with regard to the laser light, i.e. that the wave field describing the laser light changes in the same way with regard to the instantaneous deflections at different locations, except for a phase shift. In order to determine the environmental information using the analysis directed at the phase shift, the relative position of the respective detection units must be known and taken into account.Only in this case is triangulation possible, if necessary, aimed at determining the respective route.

[0010] To generate and emit the laser light, the lidar device can have at least one light or laser source. Preferably, exactly one laser source is provided. It is also conceivable that each of the detection units is assigned or comprises exactly one laser source.

[0011] It is conceivable that the phase information, and possibly amplitude and / or polarization information (explained in more detail later), is determined based on an intermediate frequency present on the part of at least one mixer of the lidar device. Each of the detection units can have a mixer or be assigned to one. The mixer has several, typically two, inputs, with a signal relating to the emitted laser light being coupled into one of the inputs and a signal relating to the respective backscattered portion of the laser light being coupled into the other of the inputs. The intermediate frequency is generated at an output of the mixer based on the input signals or laser beams and allows the phase information to be determined.

[0012] The surroundings of the motor vehicle refer in particular to the immediate surroundings of the motor vehicle, in which the objects and / or surfaces relevant to the current ferry operation are located. These objects can be moving or immobile objects, such as other road users, obstacles located particularly on or next to the roadway, buildings, curbs, or the like. Surfaces can be road surfaces.

[0013] It is particularly preferred to use the phase information to determine surface profile information describing the geometric shape of the surface or an outer surface of the object, based on which surface profile information is determined or which represents the surrounding information. The surface profile information relates in particular to a height profile of the surface or outer surface of the object. The length of the path of the backscattered part of the laser light and consequently the phase information clearly depend on the location of the scattering or reflection and thus on the geometry or extent of the surface or outer surface of the object. For example, an interferogram can be generated which includes, shows or indicates the respective associated phase shift for pixels of a corresponding image of the surroundings.Any jumps in the environmental information that occur due to the modulo values ​​can be corrected, thus creating an image of the profile of the object and / or the surface.

[0014] In the method according to the invention, it can be provided that the lidar device has exactly two detection units, wherein the known relative position is a baseline representing the distance between the detection units. The baseline can extend along the vehicle's transverse direction, so that the detection units are arranged at the same position relative to the vehicle's longitudinal direction and / or vertical direction. The detection units can be arranged on the front of the motor vehicle, for example, on the left and right sides of a bumper.

[0015] In principle, the lidar system can have more than two detection units. Accordingly, the interferometric phase analysis can be performed in pairs with respect to the detection units, whereby the corresponding baseline of the detection units used is known and used for each of these analysis processes.

[0016] The known relative position is preferably fixed. This means, in particular, that the detection units are permanently installed in the motor vehicle. The relative positions or baseline(s) can be predetermined and stored accordingly, in particular by an evaluation device configured to carry out the method according to the invention. However, the known relative position can also be variable. It is conceivable, for example, that at least one of the detection units is connected to an actuator, in particular an electromechanical one, by means of which the position of the respective detection unit can be changed. The current relative position can be determined using a control signal by means of which the actuator is controlled to change or adjust the current position of the respective detection unit.

[0017] It is conceivable that the wavelength of the laser light is constant or modulated. For example, the wavelength of the laser light can be located in the near infrared range. The wavelength can be between 7800 A and 30000 A, in particular 8500 A, 9050 A, or 15500 A. Regarding any modulation of the wavelength, it is conceivable that, plotted against time in a coordinate system, it is triangular in shape, i.e., linearly increasing and / or decreasing. The corresponding modulations, like the previously mentioned change in relative position, can be used to identify and correct jumps in the values ​​relating to the environmental information that occur due to the modulo values.Particularly preferably, the method according to the invention can provide for the laser light to be polarized, wherein a polarimetric, coherent phase evaluation is carried out to determine the environmental information and / or at least one further environmental information, in which at least one piece of polarization information is determined which relates to a phase shift between the polarized laser light and the respective backscattered part of the laser light, wherein the environmental information is additionally determined on the basis of the polarization information and / or the at least one further piece of environmental information is determined on the basis of the polarization information.

[0018] According to this embodiment, a previously unused information source is used to determine the ambient information, wherein this information source is provided by the polarization of the laser light. Thus, a phase or, more precisely, a phase shift of the polarized laser light is measured and determined directly. Reflections occurring during scattering on the object and / or surface cause polarization-specific phase changes, which can also be referred to as phase shifts or phase jumps. The polarization-specific phase changes depend on properties of the object and / or surface, in particular with regard to different polarization directions or planes. Within the scope of this embodiment, the occurring phase shift is used to determine corresponding properties.

[0019] Thus, within the framework of polarization-specific phase analysis, the polarization information is determined, which relates to a phase shift between the polarized laser light and the respective backscattered part of the laser light. The backscattered part of the laser light is also polarized under certain conditions relating to properties of the object or surface, in which case the phase shift is recorded. The use of linearly polarized light is conceivable, in which the electric field vector is always arranged within a plane and oscillates sinusoidally. This plane is also referred to as the polarization direction or polarization plane and includes, in addition to the electric field vector, the direction of propagation of the laser beam. Elliptically, in particular circularly, polarized light is conceivable, in which the tip of the electric field vector rotates elliptically, in particular circularly, around the direction of propagation.An elliptically or circularly polarized light beam can be regarded as a superposition of two linearly polarized light beams with perpendicular polarization planes, whereby the two polarizations have a phase shift, in the case of circularly polarized light of TT / 2.

[0020] According to a conceivable further development, the polarization information relates to copolarization and / or cross-polarization. Within the scope of the polarization-specific phase evaluation, an analysis is performed regarding copolarization or cross-polarization, preferably both. Copolarization means that signals are transmitted and received in the same polarization plane. Thus, in the case of copolarization, the polarized laser light is linearly polarized along an emitted polarization plane, with the detection of the backscattered laser light relating to a received polarization plane that corresponds to the emitted polarization plane. Cross-polarization means that signals are transmitted and received in different and perpendicular polarization planes.In the case of cross-polarization, the polarized laser light is linearly polarized along an emitted polarization plane, while the detection of the backscattered laser light concerns a received polarization plane that is perpendicular to the emitted polarization plane.

[0021] The polarized laser light can be linearly polarized along a first emission polarization plane and along a second emission polarization plane, wherein the first emission polarization plane and the second emission polarization plane are perpendicular to each other. Especially since the phase change due to reflection(s) from the object and / or surface depends on the polarization direction, polarizations in different polarization planes are particularly advantageous for the present purpose.

[0022] It is conceivable that the first emission polarization plane is a horizontal or vertical plane, with the second emission polarization plane being the vertical or horizontal plane. Thus, the first emission polarization plane can be the horizontal plane and the second emission polarization plane can be a vertical plane, or vice versa. The horizontal plane is the plane encompassing the vehicle's longitudinal and transverse directions, and the vertical plane is the plane encompassing the vehicle's longitudinal and vertical directions.

[0023] It is conceivable that the polarization information relates to a phase shift with respect to the same polarization plane. Thus, the polarization-specific phase shift resulting from copolarization is recorded. It is also conceivable that the polarization information relates to a phase shift with respect to different polarization planes. Thus, the phase shift resulting from cross-polarization is recorded. Based on this polarization information, the number and / or type of reflections occurring during backscattering can be determined. Thus, polarization-maintaining reflections cause specific phase shifts or jumps, which can be determined from the polarization information and allow conclusions to be drawn regarding the number of reflections that have occurred and thus the structure of the object and / or surface.

[0024] According to another conceivable development, at least one item of amplitude information relating to an amplitude of the polarized laser light and / or the respective backscattered portion of the laser light is determined based on the polarized laser light and / or the respective backscattered portion of the laser light. The ambient information is additionally determined based on the amplitude information and / or at least one further item of ambient information is determined based on the amplitude information. The amplitude of the laser light is proportional to its intensity and can be determined indirectly by measuring the intensity of the laser light.

[0025] The amplitude information preferably relates to the copolarization and / or cross-polarization of the laser light. Thus, the amplitude information depends on whether the backscattering is diffuse and thus not polarization-preserving, which depends on the surface properties of the object or surface. Specifically, a ratio, i.e., the quotient, of the amplitudes of the copolarization and the cross-polarization can be determined. In the case of diffuse scattering, in which the radiant power incident on the object or surface is not reflected with the same polarization, the linearly polarized laser light is converted into depolarized laser light, which is evident from the ratio of the amplitudes of the cross-polarization and the copolarization.

[0026] Particularly advantageously, the method according to the invention can be provided for determining at least one piece of optical information relating to the environment by means of an optical sensor and / or at least one piece of radar information relating to the environment by means of a radar sensor, wherein the environmental information is additionally determined based on the optical information and / or the radar information and / or at least one further piece of environmental information is determined based on the optical information and / or the radar information. Thus, lidar and radar sensors, as well as optical sensors, have specific strengths and weaknesses, so the simultaneous use of these sensor types and the merging of the corresponding sensor data is advantageous.It is conceivable that an image of the surroundings of the motor vehicle captured by the camera is displayed by means of a display device, wherein potential hazards and / or obstacles detected by the lidar and / or radar sensor can be marked in the image.

[0027] It is conceivable that the environmental information, and optionally the amplitude information and / or the further environmental information, relates to the presence of an obstacle arranged on a roadway and / or an edge of the roadway and / or a condition and / or wetness and / or icing of a road surface. It is also conceivable that at least one of these mentioned aspects is determined based on the environmental information and / or the additionally mentioned information(s). In particular, the surface profile information or a structure of the respective reflection surface can be determined based on the phase information. In this way, the interferometric phase analysis can be used to determine whether the road surface is smooth or rough in such a way that, for example, there is icing or a water surface on the roadway or, instead, a dry asphalt or gravel road can be inferred.

[0028] Particularly preferably, in this embodiment, the environmental information is additionally determined based on the polarization information. For example, according to the above-described considerations, it is conceivable that the polarization information relates to the number of reflections occurring during backscattering. This allows conclusions to be drawn regarding the type and / or nature of the object, whereby an obstacle or edge located on a roadway, such as a curb or the edge of a pothole, can be detected. For example, upon detection of a double and / or multiple reflection, the presence of a corresponding object can be inferred.

[0029] It is also conceivable that the polarization information relates to the type of reflection occurring during backscattering, i.e., in particular, whether it is a polarization-maintaining or a depolarizing reflection. This makes it possible to determine material parameters of the material forming the object and / or the surface and / or surface parameters of the object and / or the surface, such as surface roughness. Thus, the condition and / or wetness and / or icing of the road surface can be sensed, in particular as verification of the result obtained in this regard from the phase information. Since a polarization-maintaining or depolarizing reflection also affects the amplitude information, the results from the phase and amplitude information can be combined, for example, mutually verified.

[0030] According to the invention, it is conceivable that, based on the environmental information, and possibly the amplitude information and / or the additional environmental information, the fulfillment of a hazard condition is checked. This hazard condition is fulfilled if, based on the environmental information, and possibly the amplitude information and / or the additional environmental information, it is concluded that a potential hazard is present in the environment. Upon fulfillment of the hazard condition, a measure is automatically implemented to reduce or eliminate the hazard. The hazard condition is fulfilled, for example, if it turns out that there is an obstacle and / or a pothole and / or a wet area or puddle and / or an icy surface in front of the motor vehicle.The measure may result in the immediate reduction or elimination of the danger or in the initiation of a further action aimed at reducing or eliminating it, which must be carried out in particular by the user or driver.

[0031] Preferably, as a measure, a control command used within the framework of at least partially autonomous control of the motor vehicle can be generated and / or an output signal can be generated and output to an output device, wherein the output signal triggers a warning output for a driver, in particular an acoustic and / or visual warning output via the output device. The control command can thus trigger a reduction in speed and / or evasive action by the motor vehicle. The warning output informs the driver of the existing danger so that they can react appropriately. It is conceivable that the image of the surroundings captured by the camera is displayed by means of the display device, which can be a display, wherein the danger points and / or obstacles can be highlighted in the image by means of colored markings. The markings implement the warning outputs.The present invention also relates to a motor vehicle, comprising at least one lidar device by means of which laser light can be generated and emitted into the environment, and an evaluation device which is configured to determine at least one item of environmental information relating to a property of at least one object located in an environment of the motor vehicle and / or at least one surface located in the environment, wherein the lidar device has at least two detection units and the evaluation device is configured to determine the environmental information based on the parts of the laser light scattered back to the detection units by the object and / or the surface.The object of the present invention is achieved in that, in this motor vehicle, the evaluation device is further configured to perform an interferometric phase evaluation to determine the ambient information. Using a known relative position of the detection units to one another, at least one piece of phase information is determined, which relates to a phase difference between the parts of the laser light scattered back to the various detection units. The ambient information is determined based on the phase information. All features, advantages, and aspects explained in connection with the method according to the invention are equally applicable to the motor vehicle according to the invention and vice versa.

[0032] Further advantages and details of the present invention will become apparent from the following exemplary embodiments and the figures, which schematically show:

[0033] Fig. 1 is a view of a motor vehicle according to the invention according to an embodiment,

[0034] Fig. 2 is a flow chart of a method according to the invention according to an embodiment, which is carried out during operation of the motor vehicle of Fig. 1, and Figs. 3 - 5 are views of various situations relating to the motor vehicle of Fig. 1 in different environments, in each of which the method according to Fig. 2 is carried out.

[0035] Fig. 1 shows a plan view of a motor vehicle 1 according to the invention according to an exemplary embodiment. The motor vehicle 1 comprises a lidar device 2 with a laser source 3, by means of which laser light (not shown in detail in Fig. 1) can be generated and emitted. The laser light is emitted into an environment 4 of the motor vehicle 1, for example forward into the front area. The motor vehicle 1 comprises an evaluation device 5. The evaluation device 5 is configured to evaluate measurement signals that are detected or generated by the lidar device 2. The evaluation device 5 further functions as a control device that is configured to generate control signals by means of which the lidar device 2 can be controlled.

[0036] Within the scope of the present invention, the laser light is generated and emitted by means of the lidar device 2, wherein said light then strikes an object 6, possibly present in the environment 4, and / or a surface 7 present in the environment 4. Due to reflections that occur, the laser light is at least partially backscattered. The lidar device comprises a plurality of detection units 9, namely, in the present example, two, by means of which the portion 8 of the laser light backscattered to this detection unit 9 is detected or recorded. Although only a single laser source 3 is provided in the present exemplary embodiment, a separate laser source 3 can alternatively be provided for each of the detection units.

[0037] Fig. 1 shows the portions 8 of the laser light backscattered by each of the two detection units 9. The detection units 9 are arranged at various positions on the front of the motor vehicle 1, namely on the left and right sides of a bumper. The length of a baseline 10 extending along the vehicle's transverse direction, relating to the distance between the detection units 9, is assumed to be known, and this information is stored by the evaluation device 5. The detection units 9 are permanently installed in the motor vehicle 1, so that the relative position of the detection units 9 to one another and consequently also the length of the baseline 10 are fixed. In principle, the known relative position between the detection units 9 can be changed.For this purpose, at least one of the detection units 9 can be coupled to an electromechanical actuator by means of which the position of the respective detection unit 9 and thus the length of the respective baseline 10 can be changed.

[0038] Knowing the length of the baseline 10 allows for an interferometric phase analysis. This means that the distance between a point on the object 6 or surface 7 and the lidar device 2 differs with respect to the two detection units 9, which is particularly evident from the beam paths shown in Fig. 1. The same applies to the light path of the backscattered portion 8 of the laser light; details of this are explained below.

[0039] A further aspect of the illustrated embodiment relates to the fact that the laser light is polarized. Physical interactions occurring between the polarized laser light and the object 6 and / or the surface 7 during the scattering process may cause a change in the properties with regard to the polarization of the laser light. The changed properties can be determined from the backscattered part 8 of the laser light using the lidar device 2 and are used to draw conclusions regarding the properties of the object 6 and / or the surface 7. Specifically, during this evaluation, a polarimetric, coherent phase evaluation is carried out based on the polarized laser light and the backscattered part 8 of the laser light. The polarimetric evaluation is carried out separately for both detection units 9. Fig.Figure 2 shows a flowchart of a method according to the invention according to an exemplary embodiment, which is carried out during operation of the motor vehicle 1 of Figure 1. The evaluation device 5 is configured to carry out the method, i.e., to generate control signals and to evaluate the determined results or information.

[0040] In the first step 13 of the method, the polarized laser light is generated by the laser source 3 and emitted into the environment 4. The polarized laser light is linearly polarized along a first emission polarization plane 10 and along a second emission polarization plane 11. The polarization planes 10, 11 are perpendicular to one another and perpendicular to the propagation direction 12 of the polarized laser light. The first emission polarization plane 10 is a vertical plane, and the second emission polarization plane 11 is a horizontal plane. The polarized laser light is therefore horizontally and vertically polarized. The horizontal and vertical polarization components of the polarized laser light can be in phase, i.e., have a phase shift of 0, or out of phase and thus be elliptically polarized. In the second case, a phase shift of TT / 2 is particularly conceivable, so that the laser light is circularly polarized.

[0041] The backscattered portion 8 of the laser light is received in the second step 14 by the lidar device 2, from which phase information 15, polarization information 16, and amplitude information 17 are determined. For the sake of clarity, only one of the respective pieces of information 16, 17 is indicated in Fig. 2 by a corresponding symbol.

[0042] The phase information 15 describes a phase shift, i.e. a phase difference, between the parts 8 of the laser light scattered back to the two detection units 9.

[0043] The polarization information 16 each describes a phase shift between the polarized laser light and the respective backscattered portion 8 of the laser light. Although this is not mentioned separately below, the described determination and evaluation of the polarization information 16 is performed twice, namely once for each of the detection units 9.

[0044] The information 15, 16 is determined using intermediate frequencies provided by several mixers of the lidar device 2 (not shown in the figures). The mixers each have several inputs, with either a signal relating to the polarized laser light being fed into one of the inputs and a signal relating to one of the backscattered portions 8 of the laser light being fed into another of the inputs, or a signal relating to one of the backscattered portions 8 of the laser light being fed into one of the inputs and a signal relating to the other of the backscattered portions 8 of the laser light being fed into another of the inputs. The intermediate frequency is generated at the output of the respective mixer based on the fed-in signals and enables the determination of the information 15, 16.

[0045] With regard to the polarization information 16, it is provided that this relates to both copolarization and cross-polarization of the laser light. When evaluating copolarization, it is provided that the detection of the backscattered portion 8 of the laser light relates to a receiving polarization plane that corresponds to the respective transmitting polarization plane 10, 11. In other words, within the scope of the evaluation with regard to copolarization, it is provided that signals are transmitted and received in the same polarization plane. When evaluating cross-polarization, it is provided that the detection of the backscattered portion 8 of the laser light relates to a receiving polarization plane that is perpendicular to the respective transmitting polarization plane 10, 11.In other words, the evaluation of cross-polarization requires that signals are sent and received in polarization planes that are perpendicular to each other.

[0046] Polarization information 16 is determined as phase shifts between the polarized laser light and the backscattered portion 8 of the laser light with respect to the same polarization plane 10, 11. These phase shifts are denoted by PHH and Pvv. Polarization information 16 is determined as phase shifts between the polarized laser light and the backscattered portion 8 of the laser light with respect to different polarization planes 10, 11. These phase shifts are denoted by PVH and PHV.

[0047] The phase shift PHH describes the difference between the phase of the horizontal polarization of the emitted polarized laser light and the horizontal polarization of the corresponding backscattered part 8 of the laser light. The phase shift Pvv describes the difference between the phase of the vertical polarization of the emitted polarized laser light and the vertical polarization of the corresponding backscattered part 8 of the laser light. The phase shift PVH describes the difference between the phase of the horizontal polarization of the emitted polarized laser light and the vertical polarization of the corresponding backscattered part 8 of the laser light. The phase shift PHV describes the difference between the phase of the vertical polarization of the emitted polarized laser light and the horizontal polarization of the corresponding backscattered part 8 of the laser light.

[0048] With regard to the amplitude information 17, it is intended that this relates to the amplitude and thus the intensity of the polarized laser light as well as the backscattered portion 8 of the laser light. The amplitude information 17 also relates to both the copolarization and the cross-polarization. The amplitude information 17 is also determined using the mixers, by means of which, in addition to the phase information 15 and the polarization information 16, the amplitude information 17 can also be determined. The amplitude information 17 determines the amplitudes with respect to the copolarization and crosspolarization for the horizontal polarization and the vertical polarization of the emitted polarized laser light. For this purpose, intensity coefficients SHH, SVH, Sw, SHV are determined, which are elements of the associated scattering matrix S, also referred to as the Sinclair matrix.The intensity coefficient SHH describes the quotient of the amplitude or intensity of the horizontal polarization of the emitted polarized laser light and the horizontal polarization of the corresponding backscattered portion 8 of the laser light. The intensity coefficient Sw describes the quotient of the amplitude or intensity of the vertical polarization of the emitted polarized laser light and the vertical polarization of the corresponding backscattered portion 8 of the laser light. The intensity coefficient SVH describes the quotient of the amplitude or intensity of the horizontal polarization of the emitted polarized laser light and the vertical polarization of the corresponding backscattered portion 8 of the laser light.The intensity coefficient SHV ​​describes the quotient of the amplitude or intensity of the vertical polarization of the emitted polarized laser light and the horizontal polarization of the corresponding backscattered part 8 of the laser light.

[0049] In the third step 18, which is performed simultaneously with the second step 14, optical information 19 and radar information 20 are determined. The optical information 19 is image data of the surroundings 4 and is captured by an optical sensor 21 or a camera of the motor vehicle 1. The radar information 20 is radar data relating to the surroundings 4 and is captured by a radar sensor 22 of the motor vehicle 1.

[0050] In the fourth step 23, based on the information 15, 16, 17, 19, 20, several pieces of environmental information 24 are determined, each relating to a property of the object 6 or the surface 7. The pieces of information 15, 16, 17, 19, 20 complement each other and are also mutually checked for consistency. Details of the environmental information 24 are explained below, of which only one piece is symbolically indicated in Fig. 2, namely a piece of surface profile information 25. One of the pieces of environmental information 24 is the surface profile information 25 determined based on the phase information 15. The surface profile information 25 describes the geometric shape of the surface 7 in the submillimeter range, which can also be understood in particular as the outer surface of the object 6.The surface profile information 25 relates to or describes the geometric shape or structure of the surface 7 or the outer surface of the object 6, i.e., in particular, a corresponding height profile. The surface profile information 25 determined by means of the interferometric phase analysis thus describes, in particular, a roughness of the respective surface or outer surface. An interferogram is generated based on the surface profile information 25. The surface profile information 25 can also be present as such. The interferogram is understood to be an image of the environment 4 in which the respective associated phase shift is specified for each pixel.

[0051] Further aspects relating to the environmental information 24 are explained below with reference to Figures 3 to 5, which show the motor vehicle 1 in the environment 4, specifically with regard to various situations relating to a roadway 26 in front of the motor vehicle 1.

[0052] Thus, in Fig. 3, the roadway 26 in front of the motor vehicle 1 has several different surfaces 7, namely a dry and ice-free first surface 27 and a second surface 28 that is icy or has a puddle. Based on the depolarizing properties of the first surface 27 and the polarization-maintaining properties of the second surface 28, conclusions can be drawn about the respective road conditions. These are combined with the surface profile information 25 regarding roughness in order to identify potentially critical situations as reliably as possible.

[0053] The depolarizing properties of the first surface 27 are evident due to the diffuse scattering of the polarized laser light occurring there on the rough road surface. This can be detected using the amplitude information 17, for example by forming a ratio of the variables SHH, SW, SVH, SHV. In addition, the polarization-maintaining properties of the second surface 25 are evident due to the smooth surface of the ice or puddle, which can also be detected using the amplitude information 17. The evaluation of the polarization information 16 also allows the detection of this information, since the polarized laser light is reflected exactly once during scattering on the second surface 28, thus resulting in a corresponding polarization-specific phase shift or phase jump, which can be detected using the variables PHH, PW, PVH, PHV. In the example shown in Fig.In the example shown in Figure 3, the environmental information 24 determined in addition to the surface profile information 25 therefore relates to the condition and the wetness or icing of the surfaces 27, 28 of the roadway 26.

[0054] Furthermore, in step 23, the fulfillment of a hazard condition is checked. In the course of this, the road conditions of the roadway 26 in front of the motor vehicle 1 are analyzed using the environmental information 24. Here, it is determined that in the area of ​​the first surface 27, the condition or roughness of the roadway 26 is such that no hazard exists at this point, and that in the area of ​​the second surface 28 there is icing or a puddle, so that a potential hazard exists at this point, namely that the motor vehicle 1 could skid. The icing present on the second surface 28 means that the hazard condition is fulfilled, and in this case the method continues with the last step 29. Otherwise, i.e. if no hazard exists, the method would continue with the first step 13.

[0055] In the final step 29, a measure is automatically initiated and carried out that reduces or eliminates the danger posed by the icy second surface 28. For this purpose, a control command 30 is generated by the evaluation device 5, which is used as part of an at least partially autonomous longitudinal and / or lateral guidance of the motor vehicle 1. The control command 30 reduces the speed of the motor vehicle 1 when passing the second surface 28. Furthermore, an output signal 31 is generated by the evaluation device 5 and transmitted to an output device 32 of the motor vehicle 1. This causes a warning to be output to the driver via the output device 32, who is thereby informed of the corresponding danger.The output device 32 is a display by means of which the optical information 19 is output as an image of the environment 4, wherein in the area of ​​the second surface 28 a colored image overlay is displayed as a warning output.

[0056] In the situation shown in Fig. 4, the roadway 26 in front of the motor vehicle 1 has a pothole 33. In the area around the pothole 30, diffuse scattering of the polarized laser light occurs on the rough road surface, which can be detected as explained above, in particular using the amplitude information 17. In the peripheral area of ​​the pothole 33, there is an edge at which the polarized laser light is doubly reflected during scattering, so that a corresponding polarization-specific phase shift or phase jump occurs, which can be determined using the polarization information 16. Furthermore, the presence of the pothole 33 is determined using the interferogram determined using the phase information 15. In the area shown in Fig.In the example shown in Figure 4, the environmental information 24, in addition to the surface profile information 25, relates to the presence and location of the pothole 33. Subsequently, in step 29, the measures already explained above for reducing the danger posed by the pothole 33, i.e. the generation of the control command 30 and the output signal 31, are carried out.

[0057] In the situation shown in Fig. 5, an obstacle 34, such as object 6, is located on the roadway 26 in front of the motor vehicle 1. Similar to the pothole 33, the object 6, a polarization change of the laser light specific to this situation results. Thus, multiple reflections, in particular double reflections, occur at the edge of the obstacle 34, which in turn can be detected from the polarization information 16. Furthermore, the presence of the obstacle 34 is also evident from the interferogram determined using the phase information 15. In the example shown in Fig. 5, the environmental information 24, in addition to the surface profile information 25, therefore relates to the presence and position of the object 6 or the obstacle 34.Subsequently, in step 29, the measures already explained above to reduce the danger posed by the obstacle 34, i.e. the generation of the control command 30 and the output signal 31, are carried out.

Claims

PATENT CLAIMS:

1. A method for determining at least one piece of environmental information (24) relating to a property of at least one object (6) located in an environment (4) of a motor vehicle (1) and / or at least one surface (7) located in the environment (4), wherein laser light is generated by means of at least one lidar device (2) of the motor vehicle (1) and emitted into the environment (4), wherein the lidar device (2) has at least two detection units (9), by means of which a part (8) of the laser light scattered back from the object (6) and / or the surface (7) to the respective detection unit (9) is detected, characterized in that an interferometric phase evaluation is carried out to determine the environmental information (24), in which at least one piece of phase information (15) is determined using a known relative position of the detection units (9) to one another,which relates to a phase difference between the parts (8) of the laser light scattered back to the various detection units (9), wherein the environmental information (22) is determined on the basis of the phase information (14).

2. Method according to claim 1, characterized in that on the basis of the phase information (15) a surface profile information (25) describing the geometric shape, in particular a height profile, of the surface (7) or an outer surface of the object (6) is determined, on the basis of which the environmental information (24) is determined or which represents it.

3. Method according to claim 1 or 2, characterized in that the lidar device (2) has exactly two detection units (9), wherein the known relative position is a distance between the base line (10) representing the detection units (9) and extending in particular along the transverse direction of the vehicle.

4. Method according to one of the preceding claims, characterized in that the known relative position is fixed or variable.

5. Method according to one of the preceding claims, characterized in that the wavelength of the laser light is constant or, in particular, triangularly modulated.

6. Method according to one of the preceding claims, characterized in that the laser light is polarized, wherein in order to determine the environmental information (24) and / or further environmental information, a polarimetric, coherent phase evaluation is carried out, in which at least one item of polarization information (16) is determined which relates to a phase shift between the polarized laser light and the respective backscattered part (8) of the laser light, wherein the environmental information (24) is additionally determined on the basis of the polarization information (16) and / or the at least one further item of environmental information is determined on the basis of the polarization information (16).

7. The method according to claim 6, characterized in that the polarization information (16) relates to a copolarization and / or a cross-polarization.

8. Method according to claim 7, characterized in that that the polarization information (16) relates to a phase shift with respect to the same polarization plane (10, 11) or with respect to different polarization planes (10, 11).

9. Method according to one of claims 6 to 8, characterized in that at least one item of amplitude information (17) is determined on the basis of the polarized laser light and / or the respective backscattered part (8) of the laser light, which item of amplitude information relates to an amplitude of the polarized laser light and / or the respective backscattered part (8) of the laser light, wherein the environmental information (24) is additionally determined on the basis of the amplitude information (17) and / or at least one further item of environmental information is determined on the basis of the amplitude information (17).

10. Method according to one of the preceding claims, characterized in that at least one item of optical information (19) relating to the environment (4) is determined by means of an optical sensor (21) and / or at least one item of radar information (20) relating to the environment (4) is determined by means of a radar sensor (22), wherein the environmental information (24) is additionally determined on the basis of the optical information (19) and / or the radar information (20) and / or at least one further item of environmental information is determined on the basis of the optical information (19) and / or the radar information (20).

11. Method according to one of the preceding claims, characterized in that the environmental information (24) relates to a presence of an obstacle (34) arranged on a roadway (26) and / or an edge of the roadway (26) and / or a condition and / or wetness and / or icing of a surface (27, 28) of the roadway (26).

12. Method according to one of the preceding claims, characterized in that the environmental information (24) is used to check whether a hazard condition is met, which is met if the presence of a potential hazard in the environment (4) is inferred from the environmental information (24), wherein when the hazard condition is met, a measure is automatically carried out to reduce or eliminate the hazard.

13. The method according to claim 12, characterized in that as a measure, a control command (30) used within the framework of an at least partially autonomous control of the motor vehicle (1) is generated and / or an output signal (31) is generated and output to an output device (32), wherein the output signal (31) causes a warning output for a driver via the output device (32).

14. Motor vehicle, comprising at least one lidar device (2) by means of which laser light can be generated and emitted into the environment (4), and an evaluation device (5) which is configured to determine at least one item of environmental information (24) relating to a property of at least one object (6) located in an environment (4) of the motor vehicle (1) and / or at least one surface (7) located in the environment (4), wherein the lidar device (2) has at least two detection units (9) and the evaluation device (5) is configured to determine the environmental information (22) based on the parts (8) of the laser light scattered back to the detection units (9) by the object (6) and / or the surface (7), characterized in that the evaluation device (5) is further configured to carry out an interferometric phase evaluation to determine the environmental information (22), in which, using a be- known relative position of the detection units (9) to one another, at least one piece of phase information (14) is determined, which relates to a phase difference between the parts (8) of the laser light scattered back to the various detection units (9), the environmental information (22) being determined on the basis of the phase information (14).

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