DE102021111014A1 - Determination of a vertical position of a calibration object with a LiDAR-based environment sensor and calibration of a LiDAR-based environment sensor with a scan plane - Google Patents

Abstract

The invention relates to a method for determining a vertical position (h) of a calibration object (32), which comprises at least three elongated individual objects (28, 30) arranged in one plane, with two first individual objects (28) being arranged parallel to one another and a second individual object (30) extends between the two first individual objects (28), with a scanning plane (24) of a LiDAR-based surroundings sensor (14), in particular for calibrating the LiDAR-based surroundings sensor (14), comprising the steps of positioning the calibration object (32) in the scan plane (24) of the LiDAR-based environment sensor (14), determining the positions (38) of the individual objects (28, 30) in the scan plane (24) of the LiDAR-based environment sensor (14) with the LiDAR-based Environmental sensor (14), and determining the vertical position (h) of the calibration object (32) based on the positions of the individual objects (28, 30) in the scan plane (24) of the LiDAR-based environmental sensor (14 ). The invention also relates to a method for calibrating a LiDAR-based environmental sensor (14) with a scan plane (24) using at least one calibration object (32), the calibration object (32) comprising at least three elongated individual objects (28, 30) which are arranged in one plane, and wherein two first individual objects (28) are arranged parallel to one another and a second individual object (30) extends between the two first individual objects (28), and the calibration object (32) in the scanning plane (24) of the LiDAR -based environmental sensor (14) is positioned.

Description

The present invention relates to a method for determining a vertical position of a calibration object using a LiDAR-based environmental sensor, in particular for calibrating the LiDAR-based environmental sensor.

The present invention also relates to a method for calibrating a LiDAR-based environmental sensor, comprising determining a vertical position of the at least one calibration object according to the above method for at least three different calibration positions.

Furthermore, the present invention relates to a driving support system with a LiDAR-based environment sensor and a control unit, which are connected to one another via a data connection, wherein the LiDAR-based environment sensor is designed to receive reflections of emitted laser pulses with a scan plane and to the Transfer control unit, wherein the driving support system is designed to perform the above method for calibrating the LiDAR-based environment sensor.

LiDAR-based environmental sensors (Light Detection And Ranging) are becoming more and more important in current vehicles in order to monitor their surroundings and implement driving support systems for various support functions up to and including autonomous driving. An extrinsic calibration of LiDAR-based environmental sensors is a prerequisite for their use for many purposes. The aim is to determine the position and orientation of the LiDAR-based environmental sensors as precisely as possible.

The calibration is particularly important when other environmental sensors are fitted to the vehicle, for example cameras, so that it can be ensured that the information from the various environmental sensors is consistent in relation to the vehicle's surroundings. For example, the various environmental sensors can be calibrated sequentially or simultaneously.

The calibration can take place both in the moving vehicle and on a calibration stand. Calibration in the moving vehicle is mostly based on a feature tracking approach based on detected objects (“features”). For example, special calibration objects can be placed specifically for the calibration. Alternatively, "everyday" objects such as traffic signs, crash barriers, etc. can be used for calibration, which preferably have a known orientation (horizontal or vertical). The movement of the vehicle must be determined with the greatest possible accuracy. This requires additional sensors, which makes the calibration very complex. In addition, the identification of static objects and their tracking contain further sources of error.

With static calibration, calibration objects are placed in the field of view of the LiDAR-based environmental sensor. By knowing the positions of the calibration objects in a reference coordinate system and their representation in the point cloud of the LiDAR-based environmental sensor in the LiDAR coordinate system, the position and alignment of the LiDAR-based environmental sensor in the reference coordinate system can be determined.

In both cases, special calibration objects are preferably used for calibrating the environmental sensors, which, due to their design, facilitate detection by the environmental sensors and exact determination of their position with the environmental sensor to be calibrated. The calibration objects are preferably suitable both for detection with LiDAR-based environmental sensors and with cameras, in order to be able to calibrate the various environmental sensors with the same calibration objects. In addition, the calibration objects can be suitable for detection with radar sensors if the vehicle has such sensors.

With the different approaches, the position of the calibration objects and/or unique points on the calibration object can be uniquely determined in both coordinate systems. A transformation between the two coordinate systems and thus the extrinsic calibration between the coordinate systems is determined by a so-called point-matching algorithm.

For the detection of calibration objects with the LiDAR-based environmental sensor, the underlying measurement principle of the LiDAR-based environmental sensors is important. LiDAR-based environmental sensors used in current vehicles are typically designed to capture a large horizontal area around the vehicle. Less information is required in the vertical direction. Typical LiDAR-based environmental sensors therefore capture the environment in several scan planes (layers). A series of scan points are generated for each scan plane, which contain runtime information from received reflections and, in the case of newer LiDAR-based environmental sensors, also an intensity of the received reflections. The number of scan planes determines the vertical polar angle resolution. The azimuthal resolution in the individual scan planes is typically significantly higher. Radar sensors can also work according to the same functional principle.

For multilayer LiDAR sensors with high polar resolution, i.e. with multiple scan planes, there is a large number of known calibration objects that can be used, for example, for static calibration. For example, squares, triangles or circular sections are used to clearly determine their positions in space with the LiDAR-based environment sensor.

In the field of autonomous driving and industrial applications, however, LiDAR-based environmental sensors with few scan planes are often used for cost reasons. Particularly cost-effective LiDAR-based environmental sensors work with just one scan plane. Fewer scan planes have the additional advantage that the environment can be scanned at a higher frequency. However, these LiDAR-based environmental sensors cannot be extrinsically calibrated with sufficient accuracy using such known calibration objects. The lower the vertical resolution of the LiDAR-based environmental sensors, the more difficult it is to determine all six degrees of freedom during calibration. In the case of LiDAR-based environmental sensors with only one scan plane, calibration with such known calibration objects is significantly more difficult or even impossible. In order to be able to estimate the shapes and alignments of the calibration objects, typically at least two scan planes must intersect the calibration objects.

There is also the problem that conventional LiDAR-based environmental sensors provide inaccurate runtime information at the edges of individual objects, making assignment to the calibration object more difficult. A binary output (calibration object yes/no) of the discrete scanning of the scan plane with the scan points means that the position of the edges and above them the position of the calibration object can only be estimated discretely. Particularly in the context of a calibration, however, particularly high demands are made on the position determination of the calibration objects.

In this context, from the DE 10 2015 118 874 A1 a method for operating a sensor system of a motor vehicle is known, in which a first piece of information from an area surrounding the motor vehicle is recorded with a first sensor of the sensor system arranged locally at a first position on the motor vehicle. A second piece of information from the area surrounding the motor vehicle is recorded with a second sensor of the sensor system, which is arranged locally at a second position on the motor vehicle that differs from the first position. The first information and the second information are recorded and evaluated in relation to a common reference point of the first sensor and the second sensor on the motor vehicle and external to the sensor.

Based on the prior art mentioned above, the invention is therefore based on the object of a method for determining a vertical position of a calibration object with a LiDAR-based environment sensor, a method for calibrating a LiDAR-based environment sensor, and a driving support system with a LiDAR-based Specify environmental sensors that enable easy and reliable calibration of LiDAR-based environmental sensors with a scan plane.

The object is achieved according to the invention by the features of the independent claims. Advantageous refinements of the invention are specified in the dependent claims.

According to the invention is therefore a method for determining a vertical position of a calibration object, which comprises at least three elongated individual objects that are arranged in one plane, with two first individual objects being arranged parallel to one another and a second individual object extending between the two first individual objects, with a scanning plane a LiDAR-based environmental sensor, in particular for calibrating the LiDAR-based environmental sensor, including the steps of positioning the calibration object in the scan plane of the LiDAR-based environmental sensor, determining the positions of the individual objects in the scan plane of the LiDAR-based environmental sensor with the LiDAR-based environmental sensor, and determining the vertical position of the calibration object based on the positions of the individual objects in the scan plane of the LiDAR-based environmental sensor. A point on the object in the object coordinate system and in the lidar coordinate system is determined with high precision in the horizontal and vertical directions.

Also according to the invention is a method for calibrating a LiDAR-based environmental sensor with a scan plane using at least one calibration object, the calibration object comprising at least three elongated individual objects which are arranged in one plane, and wherein two first individual objects are arranged parallel to one another and a second Single object extends between the first two single objects, and the calibration object in the scan plane of the LiDAR-based environmental sensor, including the steps of determining a vertical position of the at least one calibration object according to the above method for at least three different calibration positions, determining a horizontal position of the at least one calibration object in the scanning plane of the LiDAR-based environmental sensor for the at least three different calibration positions, determining a vertical and horizontal reference position of the at least one calibration object for the at least three different calibration positions, and calibrating the LiDAR-based environmental sensor based on the determined vertical and horizontal positions and the vertical and horizontal reference positions of the at least one calibration object for the at least three different calibration positions.

Furthermore, according to the invention, a driving support system with a LiDAR-based environment sensor and a control unit is specified, which are connected to one another via a data connection, the LiDAR-based environment sensor being designed to receive reflections of emitted laser pulses with a scan plane and to the control unit via a data connection transferred, wherein the driving support system is designed to carry out the above method for calibrating the LiDAR-based environment sensor.

The basic idea of the present invention is therefore to carry out a reliable calibration based on just one scan plane, starting from the reflections received with the LiDAR-based environmental sensor. Using a suitable calibration object together with the properties of the LiDAR-based environmental sensor for receiving reflections in a scan plane enables reliable vertical localization of the calibration objects based solely on the position of the individual objects in the horizontal direction. In addition, due to the orientation of the scanning plane in a horizontal direction in conventional LiDAR-based environmental sensors, there is sufficient resolution in this direction to locate objects and thus also calibration objects, i.e. to determine their position in the horizontal direction. Due to its shape with the individual objects, which are arranged as specified, the calibration object used allows the vertical position of the calibration object formed by these individual objects to be determined solely based on the positions of the individual objects.

The major challenge of calibrating LiDAR-based environmental sensors when using only one scan plane is to determine the vertical position of the calibration objects. In the prior art, it is not possible to directly determine the vertical position of calibration objects with just one scan plane. In principle, this problem exists in the prior art in an identical manner for LiDAR-based environmental sensors with few scan planes, which have a low resolution in the vertical direction. With this, too, in the prior art it is practically impossible or only possible to a very limited extent to directly determine the vertical positions of conventional objects or calibration objects. The vertical position of calibration objects can only be determined directly with sufficient accuracy once LiDAR-based environmental sensors with an increased number of scan planes are used. These problems are overcome by the method according to the invention, which enables the vertical positions of the calibration objects to be determined indirectly solely based on the horizontal positions of the individual objects.

In the case of LiDAR-based environmental sensors with multiple scan planes, the specified method can be carried out in the same way in order to determine the vertical and/or horizontal positions of the objects or calibration objects with increased accuracy based on multiple scan planes or for each of the scan planes. Alternatively, multiple vertical and horizontal positions of the at least one calibration object can be determined for multiple scan planes or for each of the scan planes in order to carry out the calibration based thereon. For example, mean values can be formed over the vertical positions of the objects or calibration objects determined for the respective scan planes. As a result, calibration can be performed with increased accuracy based on multiple scan planes.

The method according to the invention can be used in an identical manner for LiDAR-based environmental sensors whose scanning planes are not aligned horizontally. In this case, the "vertical" position of the calibration object can be determined perpendicular to the corresponding scan plane of the LiDAR-based environmental sensor. The "horizontal" position then corresponds to the position in the scan plane and the "vertical" position to the position perpendicular to the scan plane. In the field of vehicles and driving support systems, however, alignment of the LiDAR-based environmental sensors with the scan plane in a horizontal direction is preferred.

The calibration object is preferably designed with a three-dimensional structure that is formed by the individual objects. The elongated individual objects can, for example, as beams or strips be formed and arranged together. The elongated individual objects can be connected to one another at their ends to form the calibration object. Additionally or alternatively, the calibration object can have a frame structure or a support structure, for example, on which the individual objects are held to form the calibration object. Alternative arrangements of the individual objects are also possible. The frame structure or support structure is preferably designed with small dimensions compared to the individual objects in order to reduce or avoid reflections on them.

The calibration object preferably has a surface, in particular as a coating, with a high reflectivity for emitted laser pulses, at least on the side of the plane for the individual objects. When the emitted laser pulses hit the surface with the high reflectivity, strong reflections of the laser pulses are generated, which can be reliably received. As a result, for example, the individual objects can be easily recognized if they have a particularly high reflectivity compared to surfaces with “natural” reflectivities. In addition or as an alternative, it is possible to generate a large dynamic range of the intensities of the reflections and to evaluate them accordingly, so that the positions of the individual objects can be reliably determined. Such high reflectivities relate in particular to reflectivities that are practically unachievable in “natural” environments.

Alternatively or additionally, the calibration object can be designed as a calibration panel. The individual objects can be formed by the surface with a high reflectivity for emitted laser pulses on the calibration board, i.e. the individual objects can be formed solely by applying a coating with a high reflectivity on the calibration board. Alternatively, the calibration panel can be composed of individual objects with a surface with a high reflectivity and objects with a surface with a low reflectivity. The reflections on the calibration panel then all have the same transit time and differ in their intensity for reflections from the individual objects and from the remaining areas of the calibration panel.

The individual objects can be arranged together in different ways to form the calibration object. All individual objects are preferably arranged at an angle to the scanning plane. The individual objects preferably have a shallow angle of intersection with the scan plane. A flat intersection angle is assumed if there is a deviation from a right angle, so that an intersection length of the individual objects with the scan plane is increased. A larger deviation from the right angle results in a larger cut length, so that more reflections are received from the individual object and the determination of the position is improved. However, the intersection angle of the individual objects in the calibration object must be selected in such a way that it can be distinguished from the expected scan plane, i.e. it is larger than the tolerance range for an expected horizontal scan plane with a tolerance range, for example. For example, the cutting angle is twice as large as the tolerance range. The first individual objects and the second individual object can have independent angles of intersection.

Each of the individual objects preferably has a uniform extension transversely to its longitudinal direction, i.e. the individual objects each have a width that does not change over their length. The width of the individual objects can be chosen differently.

In the case of the calibration object, the individual objects can be at least partially connected to one another. Alternatively, the individual objects can be arranged separately and together form the calibration object. At least in the imaginary extension of the individual objects, there is an intersection of the second individual object with the two first individual objects.

The dimensions of the at least one calibration object and/or positions of the individual objects are preferably known in order to determine the vertical and/or horizontal position of the calibration object and to calibrate the LiDAR-based environmental sensor.

When determining the vertical position of the calibration object, it is necessary for the scan plane to intersect the calibration object, with the scan plane having to intersect at least the three minimum required individual objects. The calibration object must therefore be aligned and positioned accordingly.

The calibration requires at least three positions of calibration objects to be determined in order to calibrate the LiDAR-based environmental sensor in all degrees of freedom, i.e. to determine position information for three axes and rotation information about three axes. As a constraint, the three positions of calibration objects must not lie on a straight line, because this does not provide enough information to determine the three-axis position information and the three-axis rotation information.

The positioning of the calibration object in the scan plane of the LiDAR-based environmental sensor affects a corresponding positioning of the at least one calibration object at different calibration positions that can be specified. When determining the vertical and horizontal reference position of the at least one calibration object with a further environment sensor, the at least one calibration object can in principle be freely positioned in the environment of the vehicle, so that the at least one calibration object is detected by the scanning plane.

The determination of the positions of the individual objects in the scan plane of the LiDAR-based environment sensor is carried out with the LiDAR-based environment sensor. The positions can be determined as angular positions between the individual objects and can therefore be independent of a distance from the respective calibration object. Alternatively, the positions of the individual objects can be determined as positions along a scan line or in space. Distances or lengths can be determined based on the angular positions and the distance of the calibration object.

The determination of the vertical position of the calibration object based on the positions of the individual objects in the scanning plane of the LiDAR-based environmental sensor can be based on geometric relationships depending on the at least one calibration object. In doing so, geometric relationships between the individual objects can be exploited. The vertical position is initially determined as a relative position. From this, an absolute vertical position can be determined during the subsequent calibration using the reference position of the calibration object.

The horizontal position of the respective calibration object in the scanning plane of the LiDAR-based environmental sensor for the at least three different calibration positions is determined depending on the type of the respective calibration object. For example, the horizontal position of the respective calibration object in the scan plane can be determined based on a position or multiple positions of the individual objects of the calibration object or also based on a position of a calibration table. Due to the high resolution of the LiDAR-based environmental sensor in the horizontal direction, the horizontal position of the respective calibration object can be determined easily and reliably. The position of the calibration object can be fully determined based on a distance to the calibration object, which results directly from the propagation time of the reflection received with the LiDAR-based environmental sensor.

A vertical and horizontal reference position of the at least one calibration object is determined for the at least three different calibration positions in order to calibrate the LiDAR-based environmental sensor. Based on the at least three different calibration positions, the position and alignment of the LiDAR-based environmental sensor can be adequately defined.

The LiDAR-based environmental sensor is calibrated based on the determined vertical and horizontal positions and the vertical and horizontal reference positions of the at least one calibration object for the at least three different calibration positions. A mechanical adjustment of the LiDAR-based environmental sensor may be performed by aligning the LiDAR-based environmental sensor with the vehicle. Alternatively or additionally, an image can be determined during the calibration based on the deviations between the determined vertical and horizontal positions of the at least one calibration object and the associated vertical and horizontal reference positions in order to carry out the calibration.

The control unit includes a processor and a memory to execute a program for performing an assistance function of the driving assistance system. The control unit processes sensor information provided by the LiDAR-based environmental sensor.

The data connection is designed, for example, in the manner of a bus system that is customary in the automotive sector. Various bus systems such as CAN, FlexRay, LON or others are known in this context.

LiDAR-based environmental sensors are known as such. The method can be performed with LiDAR-based environmental sensors with one or more scan planes. For LiDAR-based environmental sensors with multiple scan planes, using only one of the scan planes is sufficient.

In an advantageous embodiment of the invention, determining the vertical position of the calibration object based on the positions of the individual objects in the scanning plane of the LiDAR-based environmental sensor includes determining the vertical position of the calibration object based on the ratio of the distances between the two first individual objects and the second individual object and one Height of the calibration object to the vertical position of the calibration object. The ratio enables the vertical position of the calibration object to be determined based, for example, on the theorem of rays. This happens regardless of the angle of the scan plane with the object coordinate system. The height of the calibration object is predetermined, while the distances between the first two individual objects and the second individual object are determined using the LiDAR-based environmental sensor, namely based on the positions of the individual objects in the scan plane. By considering the ratio of the distances between the two first individual objects and the second individual object and a height of the calibration object to the vertical position, the vertical position of the calibration object can be reliably determined based on known or ascertained values.

Based on the determined positions of the individual objects in the scan plane of the LiDAR-based environmental sensor, distances between the individual objects in the scan plane can be determined. Alternatively, the distances between the individual objects can be determined as distances.

The height of the calibration object can correspond to the extent of the physical calibration object or to a height that is defined by the arrangement of the individual objects. Based on the ratio of the distances mentioned, "virtual" intersections of the individual objects can also define the dimensions, in particular the height of the calibration object.

In an advantageous embodiment of the invention, the determination of the positions of the individual objects in the scan plane of the LiDAR-based surroundings sensor with the LiDAR-based surroundings sensor includes steps for emitting a plurality of laser pulses in the scan plane of the LiDAR-based surroundings sensor, receiving reflections of the emitted laser pulses from the scanning plane, determining reflections belonging to the individual objects, and determining the positions of the individual objects based on the received reflections belonging to the respective individual object.

Individual reflections of the emitted laser pulses from the scan plane, which are received with the LiDAR-based environmental sensor, are also referred to as scan points in the following.

The majority of laser pulses are emitted in the scan plane of the LiDAR-based environmental sensor, i.e. the scan plane is defined by a propagation of the laser pulses and their reflections and the detection range of the receiving unit. The emitted laser pulses preferably have the same intensity. The laser pulses can be emitted in any order in the scan plane. One laser pulse can be emitted at a time so that a reflection is received based on it. Alternatively, multiple laser pulses can be emitted simultaneously and, based on this, multiple reflections can be received simultaneously. For this purpose, for example, a single laser pulse can be split into several laser pulses. In the case of LiDAR-based environmental sensors with multiple scan planes, scan points of the individual scan planes can be recorded one after the other or in any order, also between the different scan planes.

The scan plane is typically a substantially horizontally oriented plane, however, deviations in the scan plane from horizontal are possible based on misalignment of the LiDAR-based environmental sensor on the vehicle and/or variations in manufacturing and assembly of the LiDAR-based environmental sensor.

Receiving reflections of the emitted laser pulses from the scan plane typically includes a runtime detection from the emission of the laser pulses to the receipt of the reflections generated by them, in order to determine a distance from an object on which the laser pulse was reflected based on the detected runtime.

In an advantageous embodiment, the determination of reflections belonging to the individual object includes a comparison of propagation times of the received reflections. For example, a reflection can be determined as belonging to an individual object if this reflection has a different propagation time from the emission of the laser pulse to the receipt of the reflection compared to neighboring reflections. Correspondingly, a group of adjacent reflections from the scan plane can be determined as belonging to the respective individual object if these reflections have the same propagation time and/or if these reflections have a deviating propagation time compared to neighboring reflections. In particular during the calibration, the calibration object can be positioned in an area in which there are no other objects within a specific distance range. This can help in particular to carry out automatic recognition of the calibration object with the respective individual objects and automatic determination of reflections belonging to the calibration object and respective individual objects.

In an advantageous embodiment of the invention, the determination of the positions of the individual objects in the scanning plane of the LiDAR-based surroundings sensor with the LiDAR-based surroundings sensor includes a determination of intensities received reflections of the emitted laser pulses from the scan plane, and determining the positions of the individual objects includes determining the positions of the individual objects based on the intensities of the received reflections belonging to the respective individual object. By looking at the intensities of the received reflections, scan points that only partially cover the individual objects can help to determine the positions of the individual objects and even improve their determination. There is not only a binary distinction between scan points that capture the individual objects and scan points that do not capture the individual object, but also—based on a finite extension of the laser pulses—a degree of coverage of the individual object can be determined. The result is an increased number of scan points, which contribute to determining the positions of the individual objects and enable the positions of the individual objects to be determined with improved accuracy. In combination with the alignment of the individual objects with a flat angle of intersection, it can be ensured that an increased number of reflections of the laser pulses on the individual objects is recorded. With their different intensities, the reflections in the edge areas of the individual objects can contribute to determining the position of the respective individual object.

The same applies in principle to the determination of the horizontal position of the at least one calibration object in the scanning plane of the LiDAR-based environmental sensor.

The intensities of the received reflections are preferably determined as an integral step when receiving the reflections of the emitted laser pulses from the scan plane.

Alternatively or additionally, the determination of reflections belonging to the individual object includes a comparison of the intensities of the received reflections. Reflections with similar intensities can be attributed together to the respective individual object. For example, a group of adjacent reflections from the scan plane can be determined as belonging to the respective individual object if these reflections have approximately the same intensity. Alternatively or additionally, a group of adjacent reflections from the scan plane can be determined as belonging to the respective individual object if these reflections have an increased intensity compared to adjacent reflections. Reflections with particularly high intensities can thus be recognized as belonging to the individual object, in particular if the individual objects are designed with a high level of reflectivity. As a further alternative or in addition, a profile of the intensities of the received reflections can be considered in order to determine reflections belonging to the individual object. In this way, in particular, scan points on edges or borders of the respective individual objects can be recognized and reliably assigned to the corresponding individual object. In particular, the reflections that belong to the individual object can be determined automatically. If the individual objects have a particularly high reflectivity for the emitted laser pulses, reflections on the individual objects can be distinguished from reflections on "natural" objects, which usually have a lower intensity.

In an advantageous embodiment of the invention, determining the position of the respective individual object based on the intensities of the received reflections belonging to the individual object includes determining the received reflection belonging to the individual object with the highest intensity as the position of the individual object. The reflection with the highest intensity is regarded as a middle position of the respective individual object. In particular, if only a few reflections are received from the corresponding individual object, its position can be determined in a simple and precise manner.

Alternatively or additionally, the position of each respective individual object can be determined based on the intensities of the received reflections belonging to the corresponding individual object as the center point between edges or edges of the individual object. This can be advantageous if several laser pulses hit the respective individual object completely, so that, for example, no sharp peak of the intensity profile with a sharp maximum occurs.

As a further alternative or in addition, determining the position of the respective individual object based on the intensities of the received reflections belonging to the individual object includes determining a course of the intensity over the received reflections belonging to the corresponding individual object and a maximum value of the determined course of the intensity as the position of the respective single object. The course of the intensity can be determined, for example, as an interpolation of the intensities of the reflections belonging to the individual object.

In an advantageous embodiment of the invention, determining a vertical and horizontal reference position of the at least one calibration object includes determining the vertical and horizontal reference position of the at least one calibration object with a further environment sensor, in particular an optical camera. Through the Hermit Using the vertical and horizontal reference position with a further environment sensor, which is preferably part of the driving support system and is attached to the vehicle, the two environment sensors can be calibrated relative to one another. In this case, an absolute reference is not required for calibration. The calibration of the environmental sensors relative to each other ensures that the vehicle and in particular the driving assistance system has a reliable basis for monitoring the environment. Detections of objects with multiple environment sensors can thus be assigned to one another, so that consistent information can be generated in relation to the environment of the vehicle. In addition, based on the consistent information from the various environmental sensors, the objects can usually be localized and possibly classified with improved accuracy. In principle, the calibration can be extended to other environmental sensors, for example a radar sensor or others. In this case it is advantageous if calibration objects are designed in such a way that they have a coating with a high reflectivity for radar radiation, for example.

Accordingly, in an advantageous embodiment of the invention, the driving support system has at least one additional environment sensor, in particular an optical camera. Based on this, the driving support system can calibrate the two environmental sensors relative to one another. Alternatively or additionally, further surroundings sensors can be used, for example a further LiDAR-based surroundings sensor and/or one or more further camera(s) and/or radar sensors.

In an advantageous embodiment of the invention, determining a vertical and horizontal reference position of the at least one calibration object includes determining the calibration positions as reference positions. The reference positions are thus obtained by positioning the at least one calibration object at the specified vertical and horizontal reference positions. The LiDAR-based environmental sensor is calibrated in relation to absolute positions by positioning the calibration objects at the reference positions. In addition, the LiDAR-based environment sensor can also be positioned with the vehicle at a specified calibration position. The calibration positions as reference positions can be stored as a preset in the driving support system or entered there or transferred to it.

In an advantageous embodiment of the invention, the method includes an additional step for converting the determined vertical and horizontal positions of the at least one calibration object from a LiDAR-based coordinate system into a reference coordinate system with the vertical and horizontal reference positions of the at least one calibration object, or the method includes an additional step for converting the vertical and horizontal reference positions of the at least one calibration object from a reference coordinate system into a LiDAR-based coordinate system with the determined vertical and horizontal positions of the at least one calibration object. A common reference is therefore formed for the vertical and horizontal positions determined with the LiDAR-based environmental sensor and the vertical and horizontal reference positions in order to be able to carry out the calibration efficiently. The LiDAR-based coordinate system is a coordinate system related to the LiDAR-based environment sensor. The reference coordinate system can be a coordinate system of the additional environmental sensor. The coordinate systems of the environment sensors usually have an origin on the vehicle. When using a camera as an additional environment sensor, the 2D information of the camera must also be transformed into the reference coordinate system in order to provide three-dimensional information based on the camera, or vice versa. The reference coordinate system can also be an external coordinate system that is not related to the vehicle, especially when the calibration positions are used as reference positions. The LiDAR-based coordinate system and the reference coordinate system can also be converted into a further coordinate system, in particular when using further environmental sensors.

In an advantageous embodiment of the invention, the calibration of the LiDAR-based environmental sensor based on the determined vertical and horizontal positions and the vertical and horizontal reference positions of the at least one calibration object for the at least three different calibration positions includes minimizing distances between the determined vertical and horizontal positions and the vertical and horizontal reference positions for the at least three different calibration positions. Minimizing the distances can be done in different ways. The mathematical principles are known as such, for example based on square distances. By minimizing the distances, a best fit between the determined vertical and horizontal positions and the vertical and horizontal reference positions for the at least three different calibration positions is performed, so that all freedom grade of the LiDAR-based environmental sensor can be calibrated. A transformation can be sought for the calibration, which transforms the vertical and horizontal positions and the vertical and horizontal reference positions of the at least one calibration object for the at least three different calibration positions into the reference coordinate system. When calibrating with reference to an optical camera that provides a two-dimensional matrix with pixels, a transformation between the LiDAR-based coordinate system or the reference coordinate system, which contain three-dimensional information, and the two-dimensional matrix of the optical camera is also required. When minimizing the distances in the two-dimensional matrix with pixels, the distances can simply be minimized. Corresponding projection rules are known, for example based on the so-called pinhole camera model.

In an advantageous embodiment of the invention, the method includes positioning a calibration object at each of the at least three different calibration positions and essentially simultaneously determining the vertical and horizontal positions of the calibration objects for the at least three different calibration positions, or the method includes positioning a calibration object at each one of the at least three different calibration positions and determining the vertical and horizontal positions of the calibration object each one of the at least three different calibration positions and changing the calibration object between the at least three different calibration positions. If at least three calibration objects are used, the calibration can be carried out particularly quickly if the calibration objects are detected simultaneously by the LiDAR-based environmental sensor in order to determine their positions. At the same time, this means that the calibration objects can preferably be detected when the scan plane is detected with the LiDAR-based environmental sensor. Alternatively, it is necessary to position the vehicle with the driving support system and the associated LiDAR-based environmental sensor at different positions in order to detect the calibration objects at all calibration positions. Alternatively, the calibration can be carried out with only one calibration object, for example, by initially positioning the calibration object at a calibration position and determining the position of it. The calibration object can then be positioned at further calibration positions relative to the vehicle or the LiDAR-based environmental sensor, until all of the vertical and horizontal positions of the calibration object required for the calibration have been determined.

The invention is explained in more detail below with reference to the attached drawing based on preferred embodiments. The features shown can represent an aspect of the invention both individually and in combination. Features of different exemplary embodiments can be transferred from one exemplary embodiment to another.

• 1 eine schematische Ansicht eines Fahrzeugs mit einem Fahrunterstützungssystem mit einem LiDAR-basierten Umgebungssensor und einer Steuereinheit, die über eine Datenverbindung miteinander verbunden sind, gemäß einer ersten, bevorzugten Ausführungsform,
• 2 eine schematische Darstellung eines Kalibierobjekts gemäß einer zweiten Ausführungsform mit drei länglichen Einzelobjekten, wobei die Einzelobjekte in einer Ebene angeordnet sind und zwei erste Einzelobjekte parallel zueinander angeordnet sind, und ein zweites Einzelobjekt sich zwischen den zwei ersten Einzelobjekten erstreckt,
• 3 eine schematische Darstellung von zwei unterschiedlich ausgerichteten Einzelobjekten des Kalibrierobjekts aus 2 in Bezug auf eine Scanebene des LiDAR-basierten Umgebungssensors der ersten Ausführungsform, mit jeweils einer Kurve eines Verlaufs einer Intensität von empfangenen Reflektionen in der Scanebene,
• 4 eine schematische Darstellung des Kalibierobjekts aus 2 mit einer zusätzlichen Kurve eines Verlaufs einer Intensität von empfangenen Reflektionen in der Scanebene über eine gesamte horizontale Erstreckung des Kalibrierobjekts mit den drei Einzelobjekten,
• 5 eine schematische Darstellung eines Kalibierobjekts gemäß einer dritten Ausführungsform mit drei länglichen Einzelobjekten, wobei die Einzelobjekte in einer Ebene angeordnet sind und zwei erste Einzelobjekte parallel zueinander angeordnet sind, und ein zweites Einzelobjekt sich zwischen den zwei ersten Einzelobjekten erstreckt, mit einer Kurve eines Verlaufs einer Intensität von empfangenen Reflektionen in einer Scanebene,
• 6 eine schematische Darstellung eines Kalibierobjekts gemäß einer vierten Ausführungsform mit drei länglichen Einzelobjekten, wobei die Einzelobjekte in einer Ebene angeordnet sind und zwei erste Einzelobjekte parallel zueinander angeordnet sind, und ein zweites Einzelobjekt sich zwischen den zwei ersten Einzelobjekten erstreckt, und wobei die Einzelobjekte an ihren Enden miteinander verbunden sind,
• 7 eine schematische Darstellung eines Kalibierobjekts gemäß einer fünften Ausführungsform mit drei länglichen Einzelobjekten, wobei die Einzelobjekte in einer Ebene angeordnet sind und zwei erste Einzelobjekte parallel zueinander angeordnet sind, und ein zweites Einzelobjekt sich zwischen den zwei ersten Einzelobjekten erstreckt, und wobei die Einzelobjekte miteinander verbunden sind,
• 8 ein Ablaufdiagramm eines Verfahrens zum Kalibrieren des LiDAR-basierten Umgebungssensors des Fahrzeugs aus 1 unter Verwendung von Kalibrierobjekten aus einer der 2 bis 7,
• 9 ein Ablaufdiagramm eines Verfahrens zur Bestimmung einer vertikalen Position eines der Kalibrierobjekte aus den 2 bis 7, und
• 10 ein Ablaufdiagramm eines Verfahrens zum Bestimmen einer Position von Einzelobjekten in einer Scanebene des LiDAR-basierten Umgebungssensors des ersten Ausführungsbeispiels.

It shows

• 1 a schematic view of a vehicle with a driving support system with a LiDAR-based environment sensor and a control unit, which are connected to one another via a data connection, according to a first preferred embodiment,
• 2 a schematic representation of a calibration object according to a second embodiment with three elongated individual objects, the individual objects being arranged in one plane and two first individual objects being arranged parallel to one another, and a second individual object extending between the two first individual objects,
• 3 shows a schematic representation of two differently aligned individual objects of the calibration object 2 in relation to a scan plane of the LiDAR-based surroundings sensor of the first embodiment, each with a curve of a course of an intensity of received reflections in the scan plane,
• 4 a schematic representation of the calibration object 2 with an additional curve of a course of an intensity of received reflections in the scan plane over an entire horizontal extent of the calibration object with the three individual objects,
• 5 a schematic representation of a calibration object according to a third embodiment with three elongated individual objects, wherein the individual objects are arranged in one plane and two first individual objects are arranged parallel to one another, and a second individual object extends between the two first individual objects, with a curve of a course of an intensity from received reflections in a scan plane,
• 6 a schematic representation of a calibration object according to a fourth embodiment with three elongated individual objects, the individual objects being arranged in one plane and two first individual objects being arranged parallel to one another, and a second individual object extending between the two first individual objects, and the individual objects projects are connected at their ends,
• 7 a schematic representation of a calibration object according to a fifth embodiment with three elongated individual objects, the individual objects being arranged in one plane and two first individual objects being arranged parallel to one another, and a second individual object extending between the two first individual objects, and the individual objects being connected to one another ,
• 8th Figure 12 shows a flowchart of a method for calibrating the vehicle's LiDAR-based environmental sensor 1 using calibration objects from one of the 2 until 7 ,
• 9 a flowchart of a method for determining a vertical position of one of the calibration objects from 2 until 7 , and
• 10 a flowchart of a method for determining a position of individual objects in a scan plane of the LiDAR-based surroundings sensor of the first embodiment.

the 1 shows a vehicle 10 with a driving support system 12 according to a first preferred embodiment.

The driving assistance system 12 includes a LiDAR-based environment sensor 14, an optical camera 15 and a control unit 16, which are connected to one another via a data connection 18.

The LiDAR-based environment sensor 14 is designed to capture an environment 20 of the vehicle 10 . The detection takes place with scan points 22 in a scan plane 24 in that laser pulses are emitted in the scan plane 24 and reflections of the emitted laser pulses are received in the scan plane 24 . The scan points 22 are spanned by the received reflections of the emitted laser pulses in the scan plane 24. The scan plane 24 is spanned by the emitted laser pulses and the received reflections. In the scanning plane 24, the laser pulses are emitted with a uniform angular spacing. In addition, intensities 26 of the received reflections can be determined with the LiDAR-based environment sensor 14 . Corresponding LiDAR-based environmental sensors 14 are known as such.

Optical camera 15 is also designed to capture surroundings 20 of vehicle 10 . The detection takes place in a known manner based on a dot matrix with individual image points, which are also referred to as pixels and each include brightness information and/or color information.

The control unit 16 includes a processor and a memory to execute a program for performing an assistance function of the driving assistance system 12 . The control unit 16 controls the LiDAR-based surroundings sensor 14 and/or the optical camera 15 and receives and processes sensor information provided by the LiDAR-based surroundings sensor 14 and/or by the optical camera 15 .

The data connection 18 is designed, for example, in the manner of a bus system that is customary in the automotive sector. Various bus systems such as CAN, FlexRay, LON or others are known in this context.

With additional reference to the flowcharts of 8th until 10 a method for calibrating the LiDAR-based environmental sensor 14 using a calibration object 32 is described.

The method is carried out by way of example with the calibration object 32 that is 2 and 4 and additionally excerpts in 3 is shown. The calibration object 32 includes three elongated individual objects 28, 30 which are arranged in one plane. The individual objects 28, 30 include two first individual objects 28, which are each arranged perpendicularly and thus parallel to one another, and a second individual object 30, which extends diagonally between the two first individual objects 28. The calibration object 32 is designed as a calibration table, on which the individual objects 28, 30 are formed by applying a coating with a high level of reflectivity. Each of the individual objects 28, 30 has a uniform extension transversely to its longitudinal direction, ie the individual objects 28, 30 each have a constant width. At the in the 2 and 4 Calibration object 32 shown, the individual objects 28, 30 are not in contact.

The calibration object 32 is positioned such that the scan plane 24 intersects all of the individual objects 28, 30 thereof, as in FIGS 2 and 4 is shown.

In step S100, the method starts with positioning a calibration object 32 in each case at three different calibration positions. The horizontal and vertical coordinates of the intersection points can be determined separately or simultaneously with different positions. The three calibration objects 32 are positioned in such a way that the calibration objects 32 are simultaneously can be detected both by the LiDAR-based environment sensor 14 and by the optical camera 15 . The positioning takes place relative to the vehicle 10 or the LiDAR-based environmental sensor 14 and the optical camera 15. There are three calibration positions for the three calibration objects 32.

Step S110 relates to determining a vertical position h of the calibration object 32 for three different calibration positions. The vertical positions of the three calibration objects 32 are determined at the same time for the three different calibration positions, ie based on a simple scan of the scan plane 24. The vertical position h is in, for example 2 shown and can in principle be defined in a vertical direction up or down.

The details for determining the vertical position h of each calibration object 32 are given below with reference to the flow chart of FIG 9 described with the steps S200 to S220.

Step S120 relates to determining a horizontal position of the three calibration objects 32 in the scanning plane 24 of the LiDAR-based environmental sensor 14 for the three different calibration positions. The horizontal positions of the three calibration objects 32 are determined simultaneously for the three different calibration positions, i.e. based on a simple scan of the scan plane 24.

Determining the horizontal position of the three calibration objects 32 in the scan plane 24 of the LiDAR-based environment sensor 14 is based on the detection of the environment 20 in steps S300 to S340 discussed below. No re-acquisition of the environment 20 is required.

In the present case, the calibration objects 32 are designed as calibration panels. The horizontal position of the respective calibration object 32 in the scanning plane 24 can thus be determined based on positions of the first individual objects 28 of the calibration object 32 or also based on a position of the calibration panel itself. Based on a distance to the calibration object 32, which results directly from the propagation time of the reflection received with the LiDAR-based environmental sensor 14, the position of the calibration object 32 can be completely determined, for example.

Step S130 relates to determining a vertical and horizontal reference position of the respective calibration object 32 for the three calibration positions.

Determining a vertical and horizontal reference position of the at least one calibration object 32 includes determining the vertical and horizontal reference position of the respective calibration object 32 with the optical camera 15.

Alternatively, the vertical and horizontal reference positions are determined based on the corresponding calibration positions. The reference positions are thus obtained by positioning the calibration objects 32 at the specified vertical and horizontal reference positions. In addition, the vehicle 10 is positioned accordingly using the LiDAR-based surroundings sensor 14.

Step S140 relates to converting the determined vertical and horizontal positions h of the corresponding calibration object 32 from a LiDAR-based coordinate system into a reference coordinate system with the vertical and horizontal reference positions of the respective calibration object 32, or converting the vertical and horizontal reference positions of the corresponding calibration object 32 from one Reference coordinate system in a LiDAR-based coordinate system with the determined vertical and horizontal positions h of the respective calibration object 32. The LiDAR-based coordinate system is a coordinate system related to the LiDAR-based environmental sensor 14. In the present case, the reference coordinate system is a coordinate system of the optical camera 15. The coordinate systems have an origin on the vehicle 10. In addition, a transformation is carried out between the 2D information of the optical camera 15 and the reference coordinate system in order to generate three-dimensional information based on the two-dimensional information of the optical camera 15 provide, or vice versa.

Step S150 relates to calibrating the LiDAR-based environment sensor 14 based on the determined vertical and horizontal positions h and the vertical and horizontal reference positions of the calibration object 32 for the three different calibration positions.

The LiDAR-based environmental sensor 14 is calibrated based on the determined vertical and horizontal positions h and the vertical and horizontal reference positions of the calibration object 3 for the three different calibration positions. The position and alignment of the LiDAR-based environmental sensor 14 can be adequately defined by the three different calibration positions. Based on the deviations between the determined vertical and horizontal positions h of the calibration object 32 and the associated vertical and horizonta An image is determined for all reference positions in order to carry out the calibration.

In this case, the distances between the determined vertical and horizontal positions h and the vertical and horizontal reference positions for the three calibration positions are minimized. Minimizing the distances can be done in different ways. A transformation is sought which transforms the vertical and horizontal positions h and the vertical and horizontal reference positions of the calibration object 32 for the three different calibration positions into the reference coordinate system. All degrees of freedom of the LiDAR-based environmental sensor 14 relative to the optical camera 15 can be calibrated based on the determined positions of the three calibration objects 32 .

The method for determining the vertical position h of a respective calibration object 32, which comprises at least three elongated individual objects 28, 30 that are arranged in one plane, is also described below, with two first individual objects 28 being arranged parallel to one another and a second individual object 30 being located between the two first individual objects 28 is described in detail with a scanning plane 24 of the LiDAR-based environment sensor 14 according to step S110 above.

The method begins in step S200 with the positioning of the respective calibration object 32 in the scan plane 24 of the LiDAR-based environmental sensor 14. As a result, the scan plane 24 intersects the individual objects 28, 30 of the respective calibration object 32.

Step S210 relates to determining the positions of the respective individual objects 28, 30 in the scanning plane 24 of the LiDAR-based surroundings sensor 14 with the LiDAR-based surroundings sensor 14.

Details are given below in relation to steps S300 to S340

Step S220 relates to determining the vertical position h of the calibration object 32 based on the positions of the individual objects 28, 30 in the scanning plane 24 of the LiDAR-based environmental sensor 14.

The vertical position h of the respective calibration object 32 is initially determined as a relative position. From this, an absolute vertical position h can be determined during the subsequent calibration using the reference position of the calibration object 32 .

Starting from the determined positions of the individual objects 28, 30 in the scanning plane 24 of the LiDAR-based environmental sensor 14, distances a, b between the individual objects 28, 30 in the scanning plane 24 are determined. The determination is based on geometric relationships depending on the respective calibration object 32. For example, the vertical position h of the calibration object 32 can be determined using the theorem of rays. For example, by considering the ratio of the distances a, b of the two first individual objects 28 to the second individual object 30 and a height of the calibration object 32 to the vertical position h, the vertical position h of the calibration object 32 can be reliably determined based on known or determined values will. The height h _table of the calibration object 32 is predetermined. The height h _panel of the calibration object 32 can correspond to the extension of the physical calibration object 32 or to a height that is defined by the arrangement of the individual objects 28, 30. In the calibration object 32 of 2 and 4 "Virtual" intersections of the individual objects 28, 30 define the dimensions under consideration and thus the height h _table of the calibration object 32.

The method from step S210 for determining a position of individual objects 28, 30 in the scan plane 24 of the LiDAR-based surroundings sensor 14 and for locating a calibration object 32 with the individual objects 28, 30 for calibrating the LiDAR-based surroundings sensor 14 is described in detail.

The method begins with step S300, which includes emitting a plurality of laser pulses 22 in the scan plane 24 of the LiDAR-based environmental sensor 14. The emitted laser pulses each have the same pulse intensity, with one laser pulse being emitted at a time by the LiDAR-based environmental sensor 14 in this exemplary embodiment.

Step S310 relates to receiving reflections of the emitted laser pulses from the scan plane 24. The reflections are received by the LiDAR-based surroundings sensor 14. Receiving the reflections of the emitted laser pulses from the scan plane 24 includes a runtime detection from the emission of the laser pulses to the receipt of the corresponding reflections, so that for each scan point 22 distance information for the reflection of the emitted laser pulse is determined.

In this case, the laser pulses are emitted one after the other, so that the reflections are also received one after the other, so that in detail a sequence of repetitions of steps S300 and S310 results in order to find all scan points 22 in the scan level 24 to capture. In principle, however, it may be sufficient to detect scanning points 22 in the area of the respective individual object 28, 30, for example if its position is approximately known in advance or a rough detection is first carried out to approximately determine the position.

Step S320 relates to determining the intensities 26 of the received reflections. In this exemplary embodiment, the intensities 26 of the received reflections are determined as an integral step when the reflections of the emitted laser pulses are received from the scan plane 26 in step S110.

Step S330 relates to determining reflections belonging to the respective individual object 28, 30. Scanning points 22 can thus be assigned to the individual object 28, 30 for further processing.

Reflections belonging to the individual object 28, 30 are initially determined based on the propagation times of the received reflections. As a result, reflections from the calibration object 32 can be identified on the basis of their identical propagation times. A group of adjacent reflections from the scan plane 24 is thus determined as belonging to the respective individual object 28, 30 if these reflections have the same transit time and if these reflections have a different transit time compared to neighboring reflections.

In an additional step, the intensities 26 of the received reflections in the area of the calibration object 32 are compared. Due to the high reflectivity, reflections on the individual objects 28, 30 have an increased intensity 26 compared to reflections from other areas of the calibration object 32. Adjacent reflections of increased intensities 26 are therefore assigned to the respective individual object 28, 32 together. This includes scan points 26 at the edges of the respective individual objects 28, 30, where the laser pulses only partially impinge on the respective individual object 28, 30 and their intensity is therefore increased compared to reflections that do not originate from the respective individual objects 28, 30.

Step S340 relates to determining the position 38 of the respective individual object 28, 30 based on the intensities 26 of the received reflections belonging to the individual object 28, 30.

For this purpose, based on the intensities 26 of the received reflections belonging to the respective individual object 28, 30, a profile 34 of the intensity 26 is determined over the received reflections belonging to the individual object 28, 30. The profile 34 of the intensity 26 is interpolated based on the reflections belonging to the respective individual object 28, 30. Various mathematical methods of interpolation are known per se to those skilled in the art and can be used. For the calibration object 32 used here, the profiles 34 of the intensity 26 are in FIG 3 and 4 shown. The curves 24 of the intensity 26 each have a maximum 36 (peak). The maximum 36 of the determined profile 34 of the intensity 26 indicates the position 38 of the respective individual object 28, 30.

Based on the positions 38 of the individual objects 28, 30, a position determination for the calibration object 32 can take place, as exemplified in FIG 2 is shown. There is a relationship between the vertical position h of an intersection point 40 of the scan plane 24 with the second individual object 30 and the distances a, b between the positions 38 of the individual objects 28, 30.

Alternatively, the procedure with the in 6 shown calibration object 32 are carried out, which is not designed as a calibration panel. The calibration object 32 is designed with a three-dimensional structure, which is formed by the individual objects 28, 30. As a result, the reflections belonging to the individual object 28, 30 are determined while simultaneously taking into account the propagation times of the reflections and their intensities 26. A prior determination of reflections belonging to the calibration table can be omitted.

The elongate individual objects 28, 30 can, for example, be in the form of beams or strips and can be arranged together. Additionally or alternatively, the calibration object 32 can have a frame structure or a support structure on which the individual objects 28, 30 are held to form the calibration object 32. The frame structure or support structure is designed with small dimensions compared to the individual objects 28 , 30 .

For the calibration object 32 off 6 the second individual object 30 is connected at its ends to one end of each of the first individual objects 28 . In addition, the alignment of the second individual object 30 with the calibration object 32 is in 6 compared to the calibration object 32 in the 2 and 4 vice versa. Incidentally, the calibration objects 32 of 2 and 6 can be used as an alternative to carrying out the method described above.

The method described above is preferably carried out with a calibration object 32 that 5 is shown. This in 5 presented The calibration object 32 presented also includes three elongated individual objects 28, 30 which are arranged in one plane. Two first individual objects 28 are arranged parallel to one another, and a second individual object 30 extends between the two first individual objects 28. The calibration object 32 from 5 differs from the previously described calibration objects 32 from the 2 and 4 in that all individual objects 28, 32 have flat intersection angles α with the scanning plane 24. The intersection angles α are each set to about 45° here, so that they differ from the expected scan plane 24 . In addition, the individual objects 28, 30 are connected to one another at their ends.

Also the calibration object 32 off 5 is designed as a calibration panel. The individual objects 28, 30 are formed on the calibration table by a surface with a high reflectivity for emitted laser pulses.

7 shows another calibration object 32. The calibration object 32 also includes three elongated individual objects 28, 30, which are arranged in one plane. Two first individual objects 28 are arranged parallel to one another, and a second individual object 30 extends between the two first individual objects 28. The calibration object 32 from 7 is designed with the individual objects in an H-shape. Rotating the calibration object 32 results in a calibration object 32 similar to the calibration object 32 5 formed, in which all individual objects 28, 30 have flat intersection angles α with the scanning plane 24. The height h _panel of the calibration object 32 results from the intersections of the individual objects 28, 30, so that the height h _panel in this case is smaller than the extent of the physical calibration object 32.

reference list

10

vehicle

12

driving support system

14

LiDAR-based environmental sensor

15

further environment sensor, optical camera

16

control unit

18

Data Connection

20

vicinity

22

scan point

24

scan plane

26

intensity

28

first single object

30

second single object

32

calibration object

34

course of the intensity

36

maximum

38

position

40

intersection

a

cutting angle

H

vertical position

hboard

height (calibration object)

a

Distance

b

Distance

QUOTES INCLUDED IN DESCRIPTION

This list of documents cited by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent Literature Cited

• DE 102015118874 A1 [0014]

Claims (12)

Method for determining a vertical position (h) of a calibration object (32), which comprises at least three elongate individual objects (28, 30) which are arranged in one plane, with two first individual objects (28) being arranged parallel to one another and a second individual object ( 30) extends between the two first individual objects (28), with a scanning plane (24) of a LiDAR-based environment sensor (14), in particular for calibrating the LiDAR-based environment sensor (14), comprising the steps Positioning the calibration object (32) in the scan plane (24) of the LiDAR-based environmental sensor (14), Determining the positions (38) of the individual objects (28, 30) in the scanning plane (24) of the LiDAR-based surroundings sensor (14) with the LiDAR-based surroundings sensor (14), and Determining the vertical position (h) of the calibration object (32) based on the positions of the individual objects (28, 30) in the scanning plane (24) of the LiDAR-based environmental sensor (14). procedure after claim 1 , characterized in that determining the vertical position (h) of the calibration object (32) based on the positions of the individual objects (28, 30) in the scanning plane (24) of the LiDAR-based environmental sensor (14) involves determining the vertical position (h ) of the calibration object (32) based on the ratio of the distances of the two first individual objects (28) to the second individual object (30) and a height (h _panel ) of the calibration object (32) to the vertical position (h) of the calibration object (32) includes. Procedure according to one of Claims 1 or 2 , characterized in that the determination of the positions (38) of the individual objects (28, 30) in the scanning plane (24) of the LiDAR-based surroundings sensor (14) with the LiDAR-based surroundings sensor (14) comprises the following steps: transmission of a plurality Laser pulses in the scanning plane (24) of the LiDAR-based environmental sensor (14), receiving reflections of the emitted laser pulses from the scanning plane (24), determining reflections belonging to the individual objects (28, 30), and determining the positions (38) of the Individual objects (28, 30) based on the received reflections belonging to the respective individual object (28, 30). procedure after claim 3 , characterized in that the determination of the positions (38) of the individual objects (28, 30) in the scanning plane (24) of the LiDAR-based surroundings sensor (14) with the LiDAR-based surroundings sensor (14) involves a determination of intensities (26) of received reflections of the emitted laser pulses from the scanning plane (24), and determining the positions (38) of the individual objects (28, 30) includes determining the positions (38) of the individual objects (28, 30) based on the intensities (26) of the includes received reflections belonging to the respective individual object (28, 30). Method for calibrating a LiDAR-based environmental sensor (14) with a scan plane (24) using at least one calibration object (32), the calibration object (32) comprising at least three elongated individual objects (28, 30) arranged in a plane , and wherein two first individual objects (28) are arranged parallel to one another and a second individual object (30) extends between the two first individual objects (28), and the calibration object (32) in the scanning plane (24) of the LiDAR-based environmental sensor (14 ) is positioned, comprising the steps of determining a vertical position (h) of the at least one calibration object (32) by the method according to any one of Claims 1 until 4 for at least three different calibration positions, determining a horizontal position of the at least one calibration object (32) in the scanning plane (24) of the LiDAR-based environmental sensor (14) for the at least three different calibration positions, determining a vertical and horizontal reference position of the at least one calibration object (32 ) for the at least three different calibration positions, and calibrating the LiDAR-based environmental sensor (14) based on the determined vertical and horizontal positions (h) and the vertical and horizontal reference positions of the at least one calibration object (32) for the at least three different calibration positions. procedure after claim 5 , characterized in that determining a vertical and horizontal reference position of the at least one calibration object (32) includes determining the vertical and horizontal reference position of the at least one calibration object (32) with a further environment sensor (15), in particular an optical camera (15). . Procedure according to one of Claims 5 or 6 , characterized in that the determination of a vertical and horizontal reference position of the at least one calibration object (32) comprises a determination of the calibration positions as reference positions. Procedure according to one of Claims 5 until 7 , characterized in that the method includes an additional step for converting the determined vertical and horizontal positions (h) of the at least one calibration object (32) from a LiDAR-based coordinate system into a reference coordinate system with the vertical and horizontal reference positions of the at least one calibration object (32) comprises, or the method comprises an additional step for converting the vertical and horizontal reference positions of the at least one calibration object (32) from a reference coordinate system into a LiDAR-based coordinate system with the determined vertical and horizontal positions (h) of the at least one calibration object (32). Procedure according to one of Claims 5 until 8th , characterized in that the calibration of the LiDAR-based environmental sensor (14) based on the determined vertical and horizontal positions (h) and the vertical and horizontal reference positions of the at least one calibration object (32) for the at least three different calibration positions minimizes distances between the determined vertical and horizontal positions (h) and the vertical and horizontal reference positions for the at least three different calibration positions. Procedure according to one of Claims 5 until 9 , characterized in that the method comprises positioning one calibration object (32) at each of the at least three different calibration positions and essentially simultaneously determining the vertical and horizontal positions (h) of the calibration objects (32) for the at least three different calibration positions, or the method involves positioning a calibration object (32) at one of the at least three different calibration positions and determining the vertical and horizontal positions (h) of the calibration object (32) at one of the at least three different calibration positions and changing the calibration object (32) between includes the at least three different calibration positions. Driving support system (12) with a LiDAR-based environment sensor (14) and a control unit (16), which are connected to one another via a data connection (18), the LiDAR-based environment sensor (14) being implemented with a scan plane (24) reflections to receive emitted laser pulses and to transmit them to the control unit (16) via a data connection (18), the driving assistance system (12) being implemented, the method for calibrating the LiDAR-based environmental sensor (14) according to one of Claims 5 until 10 to perform. Driving support system (12) after claim 11 , characterized in that the driving support system (12) has at least one further environment sensor (15), in particular an optical camera (15).

Images