Method for operating a headlight device and headlight device

Abstract

The invention relates to a method and operation of a headlight device (2) of a vehicle (1), wherein a light projection (L) is projected by means of the headlight device (2) onto a roadway (F) in front of the vehicle (1). According to the invention, it is provided that: - a section of a future position trajectory of the vehicle (1) on the roadway (F) is represented by means of the light projection (L), and - a curvature of the light projection (L) is determined as a function of a current steering angle of the vehicle (1), a current yaw rate of the vehicle (1), and the trajectory of a section of the roadway (F) ahead. Furthermore, the invention relates to a headlight device (2).

Description

The invention relates to a method for operating a headlight device of a vehicle. Furthermore, the invention relates to a headlight device for carrying out the method. From DE 10 2020 007 757 A1 a method for adjusting vehicle lighting when driving on a construction site and a vehicle are known. US 2024 / 0317208 A1 describes a method and a device for controlling the path of a vehicle on a roadway. Furthermore, DE 10 2017 223 451 A1 discloses a method for illuminating a roadway area by projecting a trajectory and a vehicle. DE 10 2011 012 741 A1 describes a method for operating a direction-dependent swiveling vehicle lighting system, in which the current position of a vehicle, its longitudinal orientation, and the road ahead are determined. Based on the road ahead, a future trajectory of the vehicle is determined, and a cornering light anticipation distance is specified. A cornering light anticipation is calculated up to the specified distance. Using this predicted angle of incidence, a cornering light angle is determined to adjust the vehicle lighting. This angle is limited by the longitudinal orientation of the vehicle and the road edge running laterally to the road. WO 2017 / 214648 A1 describes a method for generating a light distribution with a vehicle headlight, comprising a light source, a projection optic, a control unit, an output unit, and an optoelectronic component that includes a controllable arrangement of several individually adjustable optoelectronic elements in the form of a two-dimensional matrix. The image resolution is defined by the product of the number of rows and columns of the matrix. The vehicle headlight is configured to emit light from the light source towards the optoelectronic component, modulate it by means of the optoelectronic component, and project it towards the projection optic to form a light image in front of the vehicle. The control unit is connected to the output unit. The output unit is connected to the optoelectronic component and controls the optoelectronic elements.The control unit stores a light model. From this light model, the control unit creates a two-dimensional light matrix and arranges this matrix within a two-dimensional image matrix according to a position parameter. The control unit then transmits this image matrix to the optoelectronic component via the output unit. DE 10 2006 004 764 A1 describes a method for operating a vehicle lighting system that swivels depending on the direction of travel, comprising the process steps of: determining the current direction of travel of a vehicle, determining an immediately subsequent direction of travel, and taking into account the current direction of travel and the subsequent direction of travel when swiveling the vehicle lighting depending on the direction of travel. DE 10 2024 000 189 A1 describes a method for operating a vehicle assistance system, in which the lateral distance of the vehicle to a lane marking is detected and displayed. If a narrowing of the lane is detected ahead of the vehicle, a guide surface corresponding to at least one vehicle width is projected onto a roadway in front of the vehicle. The invention is based on the objective of providing a method for operating a headlight device of a vehicle and a headlight device. The problem is solved according to the invention by a method which has the features specified in claim 1 and by a headlight device which has the features specified in claim 8. Advantageous embodiments of the invention are the subject of the dependent claims. A method for operating a vehicle's headlight device involves projecting a light beam onto the roadway ahead of the vehicle. This light beam represents a segment of the vehicle's future position on the roadway, and its curvature is determined based on the vehicle's current steering angle, yaw rate, and the path of the section of the roadway ahead.In this process, a future trajectory of the vehicle is determined in the section of the future position profile of the vehicle based on a ratio formed from a radius based on a future steering angle of the vehicle and a radius based on a future yaw rate of the vehicle, whereby in determining the ratio the radius based on the future yaw rate of the vehicle is weighted more heavily as the speed of the vehicle increases. By applying the method, the representation of the light projection in dynamic driving scenarios is optimized while maintaining a representation of the lateral position of the vehicle and, in part, an expected driving trajectory of the vehicle for a given steering behavior. Light projection assists the driver of the vehicle during operation by allowing the vehicle to be guided by means of the light projection, illuminating the roadway and visually indicating the vehicle's driving behavior. In one implementation, the course of the section of the road ahead is determined using signals from environmental sensors and / or map data. This provides the vehicle with information about the road's course, allowing it to detect the curvature of an upcoming curve and adjust the light projection accordingly. In another embodiment, the ratio is determined using a weighting factor, where the weighting factor depends on the speed of the vehicle and is determined, for example, as follows: where: w(v) is the weighting factor dependent on the speed of the vehicle, KSA is a curve curvature based on a steering angle of the vehicle, and KY is a curve curvature based on the yaw rate of the vehicle. In one implementation, a predetermined number of coordinates of a circular arc, based on a determined curvature, and a predetermined number of coordinates of the path of a lane centerline of a vehicle's lane are fused to form a future lane trajectory for the vehicle, which forms the basis for light projection. Specifically, ten coordinates are used as the predetermined number in each case. For the merged points (x, yF) the following applies, for example: In one implementation, the weighting of the coordinates of the vehicle's lane centerline increases with increasing distance in the direction of travel, because a prediction represented by light projection becomes implausible with increasing distance, assuming subsequent counter-steering. This means that the light projection aligns itself more closely with the lane centerline as the distance increases. In one possible design, the light projection is projected in front of the vehicle as a guide carpet and / or as at least a guide line, thereby illuminating the roadway from the vehicle and visually indicating the vehicle's driving behavior. In another possible implementation, a light projection is displayed as a guide surface in front of the vehicle. At a point of contact on the roadway, the light projection is aligned perpendicular to a tangent of a determined future guide spline of the vehicle and adjusted to a curve radius. The light projection is thus aligned with the roadway's contours, allowing the driver to deduce from the projection that a curve lies ahead. In one embodiment, a light projection is used as a guide line in front of the vehicle, and the curvature of at least one guide line is aligned with the future position trajectory in order to illuminate the roadway in front of the vehicle and to indicate the vehicle's driving behavior. The invention further relates to a headlight device for carrying out a method for operating the headlight device, which comprises a control unit and at least one headlight, wherein the control unit is configured to control the at least one headlight in order to project a light projection onto a roadway in front of the vehicle. The control unit is configured to control the at least one headlight such that the light projection represents a section of a future position trajectory of the vehicle on the roadway and to determine the curvature of the light projection as a function of a current steering angle of the vehicle, a current yaw rate of the vehicle, and the trajectory of a section of the roadway ahead.The headlight device is further designed to determine a future trajectory of the vehicle in the section of the future position path of the vehicle based on a ratio formed from a radius based on a future steering angle of the vehicle and a radius based on a future yaw rate of the vehicle, and to give greater weight to the radius based on the future yaw rate of the vehicle when determining the ratio as the speed of the vehicle increases. The headlight device makes it possible to create a light projection that guides a driver in the operation of the vehicle, illuminates the road and shows the vehicle's driving behavior. For this purpose, at least one headlight in one version has a plurality of individually and / or group-controllable light sources, so that it is possible to dynamically adjust the curvature of the light projection depending on the current steering angle of the vehicle, the current yaw rate of the vehicle and the course of a section of the road ahead. Exemplary embodiments of the invention are explained in more detail below with reference to drawings. Figure 1 schematically shows a top view of a roadway with a curve and a vehicle traveling on the roadway at two different positions of the curve; Figure 2 schematically shows a top view of another roadway with a vehicle, a lane trajectory, a steering trajectory, and an exponentially weighted fused trajectory; Figure 3 schematically shows a top view of a curve and a vehicle with an orientation of a light projection from a headlight device of the vehicle; Figure 4 schematically shows a top view of a roadway section with a vehicle entering a curve, a steering trajectory of the vehicle, and a fused trajectory; and Figure 5 schematically shows a top view of a roadway section with a vehicle exiting a curve, a steering trajectory of the vehicle, and a fused trajectory. Corresponding parts are marked with the same reference symbols in all figures. Fig. 1 shows a top view of a roadway F with a curve and a vehicle 1 traveling on a right-hand lane F1 of the roadway F at two different positions P1, P2 of the curve, wherein the vehicle 1 enters the curve at a first position P1 and exits the curve at a second position P2. The vehicle 1 has a headlight assembly 2, which includes a control unit 2.1 and two headlights 2.2, in particular two front headlights, wherein the control unit 2.1 is configured to control the headlights 2.2 such that a light projection L is projected onto the roadway F in front of the vehicle 1. For this purpose, the headlights 2.2 each have a plurality of light sources that can be controlled individually and / or in groups by means of the control unit 2.1. The light projection L is projected as a guide carpet onto the roadway F, i.e., onto the right lane F1, in front of the vehicle 1, according to the embodiments shown in Fig. 1 and Fig. 3, whereby guide lines can alternatively also be projected as a light projection L onto the roadway F. In particular, the light projection L is projected onto the roadway F in front of the vehicle 1 in order to guide a driver of the vehicle 1 during the driving operation of the vehicle 1, to illuminate the right lane F1, in particular to light it up, and to show the vehicle 1's own driving behavior in both manual and automated driving modes. In order to correctly represent the light projection L, it is necessary to accurately determine information about the instantaneous position P1, P2 of vehicle 1 and translate it into a corresponding light image on an image array of the headlights 2.2. This determination is generally achieved by means of a perspective transformation of fixed light distributions, for example in the form of a rectangle, on the image array. This results in an approximation of a desired light projection L, which, however, does not correspond to the actual road path, in particular the lane path V of vehicle 1, or to a driving trajectory T of vehicle 1. When the vehicle 1 is traveling on a roadway F with a changing curvature, the current trajectory T of the vehicle 1 does not correspond to the roadway, in particular a lane V, in front of the vehicle 1, although a steering movement is executed correctly for a currently traversed driving situation, as shown in Fig. 1. At the initial position P1 of vehicle 1, it is traveling straight ahead, where no steering movement is required to enter the curve and therefore none is performed, so the trajectory T continues straight ahead. If the trajectory T is compared with a lane path V, the difference between the straight-ahead trajectory T and the curved lane path V increases along the curve. Conversely, a similar effect can be observed at the second position P2 of vehicle 1, where vehicle 1 exits the curve shortly thereafter. To maintain a lane, the driver of vehicle 1 must perform a steering maneuver at the second position P2. The resulting steering angle leads to a misleading representation of the light projection L, because although the roadway F, and in particular lane F1, of vehicle 1 will soon run straight ahead, the light projection L is completely curved due to the ongoing steering maneuver of vehicle 1 and is projected onto lane F1 in front of vehicle 1. The curvature of the light projection L thus results from steering action. If the current driving trajectory T is projected as a light projection L in front of vehicle 1, the light projection L does not correspond to a future lane path V, whereas if the lane path F is projected as a light projection L onto the roadway F in front of vehicle 1, the light projection L does not correspond to the current driving behavior of vehicle 1. Therefore, no feedback can be given to the driver of vehicle 1 regarding the current steering behavior of vehicle 1 or where vehicle 1 is currently located in relation to the lane path V. For headlight device 2, which uses a driving trajectory T as the basis of the light projection L, a current steering movement of the vehicle 1 serves as the main input variable, so that the light projections L, as shown in Fig. 1, do not correspond to the future lane path V immediately in front of the vehicle 1. If a lane profile V is used as the input variable, no driving trajectory T of vehicle 1 and a lateral vehicle position are displayed by means of the light projection L, the lane F1 of vehicle 1 is additionally illuminated without assistance function. For the optimized representation of the light projection L with assistance function, i.e. a future position path of the vehicle 1, a procedure described below is provided, in which a determination for the representation of the light projection L is carried out on the basis of several support points in a world coordinate system as well as an introduction of values ​​with regard to a lane path V and an orientation of the light projection L. Based on a road reconstruction, for example based on signals recorded by an environmental sensor, in particular a camera directed in front of the vehicle 1 and / or a lidar-based detection unit, and / or based on highly accurate map data available on the vehicle, a road course, in particular a lane course V, in particular the lane F1 of the vehicle 1, is determined. This determined lane path V is transmitted, for example, via boundary points of a lateral lane boundary B, in particular a lane marking, to the control unit 2.1 and / or another control unit (not shown) for image calculation. In particular, these boundary points are plotted in a three-dimensional coordinate system, for example, the world coordinate system. For a calculation of the vehicle 1's trajectory T based on steering behavior, the following applies: where RSA denotes a radius of the trajectory T based on the steering angle ∂ and a wheelbase l, and RYa denotes a radius based on a yaw rate. However, both radii are subject to errors due to driving phenomena such as slip and steering gradients, so a composite radius is determined: where a value ω represents a weighting factor which determines a ratio of the radius based on the steering angle and the radius based on the yaw rate. The weighting factor can be chosen statically or dynamically. Simulations show that, with a dynamic choice, adjusting the weighting factor based on vehicle speed is effective. To achieve a result that closely matches the actual radius, the influence of the radius based on the yaw rate is increased with increasing vehicle speed. Possible combinations were empirically determined: where w(v) corresponds to a weighting dependent on the vehicle speed υ, KSA to a curve curvature based on the steering angle, and KY to a curve curvature based on the yaw rate. One approach involves fusing the coordinates (xi,yCi) of a circular arc, based on a calculated curvature of the curve ahead of vehicle 1, with the coordinates (xi,yLi) of the lane centerline of vehicle lane F1 ahead of vehicle 1. Specifically, a transverse value is determined from the coordinates representing the transverse coordinates of the circular arc, and a transverse value is determined based on the coordinates, particularly the transverse coordinates, relating to the lane centerline. Ten coordinates are used for each calculation. In a prototypical implementation, the fusion of the coordinates (xi,yCi) and (xi,yLi) is initially achieved by a weighted average of both original values ​​yCi and yLi, although other approaches, such as a Kalman filter, are also possible. For determined fused points (x, yF) the following applies: In the curve scenarios shown in Fig. 1, a prediction represented by the light projection L, in particular of the lane path V, becomes implausible with increasing distance, assuming subsequent counter-steering. The weighting of a lane component w(i) thus increases exponentially with an index i and therefore with a curve of the light projection L, as shown in Fig. 2. The following applies: Fig. 2 shows a steering trajectory TL, lane trajectory Ts and an exponentially weighted fused trajectory TF. Additionally, as shown in Fig. 3, the light projection L, representing the future position of the vehicle 1, is oriented perpendicular to a tangent t of a determined guide spline s at a point of contact A of the light projection L. This means that the lower and upper edges defining the light projection L do not run parallel to the front of the vehicle, but perpendicular to the respective tangent t at a tangent point p, which corresponds to the point of contact A in Fig. 3. Figures 4 and 5 each show a roadway F with a vehicle 1 and its steering trajectory TL and a fused trajectory TF. In Figure 4, the vehicle 1 enters a curve, and in Figure 5, the vehicle 1 exits the curve. In the scenarios shown in Figs. 4 and 5, it becomes apparent that a difference still exists between the fused trajectory TF (future lane trajectory Ts) and the respective steering trajectory TL, although this difference is less pronounced. The remaining difference allows the driver of vehicle 1 to still understand that maintaining the current steering angle may result in leaving their lane F1 in the foreseeable future. The method enables an optimized representation of the light projection in dynamic scenarios while maintaining a depiction of the lateral position and, in part, the expected driving trajectory T of vehicle 1 under a given steering behavior. Through the fusion, or rather the gradual transition with distance, of the steering trajectory TLhin to the tracking trajectory Ts, misleading representations at a distance can be reduced. Support for the driver of vehicle 1 is still provided, but the behavior of the light projection L can be perceived as more harmonious and less distracting for the driver.

Claims

Method for operating a headlight device (2) of a vehicle (1), wherein: - a light projection (L) is projected by means of the headlight device (2) onto a roadway (F) in front of the vehicle (1), - a section of a future position path of the vehicle (1) on the roadway (F) is represented by means of the light projection (L), - a curvature of the light projection (L) is determined as a function of a current steering angle of the vehicle (1) and a current yaw rate of the vehicle (1) and a path of a section of the roadway (F) in front of it,- a future trajectory of the vehicle (1) in the section of the future position path of the vehicle (1) is determined based on a ratio formed from a future steering angle of the vehicle (1) and a radius (RYaw) based on a future yaw rate of the vehicle (1), and - in determining the ratio, the radius (RYaw) based on the future yaw rate of the vehicle (1) is weighted more heavily as the speed of the vehicle (1) increases. Method according to claim 1, characterized in that the course of the section of the preceding roadway (F) is determined on the basis of signals recorded by an environmental sensor and / or on the basis of recorded map data. Method according to one of the preceding claims, characterized in that a predetermined number of coordinates of a circular arc based on a determined curvature and a predetermined number of coordinates of a course of a lane center of a lane (F1) of the vehicle (1) are fused to form a future lane trajectory (TS) for the vehicle (1). Method according to claim 3, characterized in that with increasing distance in the direction of travel of the vehicle (1) the weighting of the coordinates of the course of the center of the lane (F1) of the vehicle (1) increases. Method according to one of the preceding claims, characterized in that the light projection (L) is projected as a guide carpet and / or at least a guide line in front of the vehicle (1). Method according to claim 5, characterized in that, in the case of a light projection (L) projected as a guide carpet in front of the vehicle (1), the light projection (A) is aligned at a contact point (A) on the roadway (F) perpendicular to a tangent (t) of a determined guide spline (s) of the vehicle (1) and is displayed adapted to a curve radius. Method according to claim 5 or 6, characterized in that, in the case of a light projection (L) projected as a guide line in front of the vehicle (1), a curvature of the at least one guide line is aligned with the future position path. Headlight device (2) for carrying out a method according to one of the preceding claims, comprising a control unit (2.1) and at least one headlight (2.2), wherein the control unit (2.1) is configured to control the at least one headlight (2.2).2) to control such that the light projection (L) represents a section of a future position path of the vehicle (1) on the roadway (F) and- to determine a curvature of the light projection (L) as a function of a current steering angle of the vehicle (1) and a current yaw rate of the vehicle (1) and a path of a section of the roadway ahead (F), wherein the headlight device (2) is designed,- to determine a future trajectory of the vehicle (1) in the section of the future position path of the vehicle (1) on the basis of a ratio formed from a future steering angle of the vehicle (1) and a radius (RYaw) based on a future yaw rate of the vehicle (1) and- to give greater weight to the radius (RYaw) based on the future yaw rate of the vehicle (1) when determining the ratio as the speed of the vehicle (1) increases. Headlight device (2) according to claim 8, characterized in that the at least one headlight (2.2) has a plurality of individually and / or group controllable light sources.

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