Methods for detecting unevenness in the road surface and detection systems

Abstract

One aspect of the invention relates to a method for detecting unevenness in the ground (11) on a road (12) using a detection system (1) on a motor vehicle (10), comprising the following steps: - Illuminating the ground surface (16) using a light source (14) of the motor vehicle (10); - Detecting a light-dark boundary on the illuminated ground surface (16) using at least one optical detection device (18); - Determining a first angle (α) SW ) between an optical axis (18a) of the optical detection device (18) and a beam direction (14a) of a light source (14); - Determining a second angle (α) K ) between the optical axis (18a) of the optical detection device (18) and a horizontal plane (E); - Calculating a new headlight angle (α) SW n) depending on the first angle (α SW ), the second angle (α K) and a measured time difference (Δt) between the expected and the actual time of driving over a road surface irregularity; - storing the new headlight angle (α) SWn ) as an initial value for future measurements; and - calculating the X and Z coordinates of a measurement point on the road (12) based on the new headlight angle (α) SWn ), the second angle (α K ) and the known geometric properties of the motor vehicle (10). Furthermore, the invention relates to such a detection system (1).

Description

[0001] The invention relates to a method for detecting unevenness in the road surface according to claim 1. Furthermore, the invention relates to a detection system.

[0002] The measurement of road surface irregularities is used in the automotive sector for various applications, including comfort, driver assistance, and brake control systems. In applications requiring highly accurate measurements as input, such as for active suspension systems, stereo camera systems are typically employed. These systems detect irregularities in the millimeter range, but currently only function reliably with sufficient ambient light. Lidar systems, which can also be used to detect road irregularities, are capable of detecting them even in darkness, but due to their time-of-flight measurement principle, they are significantly less accurate than triangulation-based systems. Similarly, monocular camera systems that measure the road surface using methods such as "Structure from Motion" are considerably less accurate.

[0003] To measure ground irregularities using state-of-the-art technology, mono and stereo camera systems as well as lidar systems are currently employed in the automotive sector. While stereo camera systems achieve the highest accuracy due to their triangulation measurement principle, they do not function reliably enough in darkness to be offered as a service in customer operations. Mono camera systems use the "structure-from-motion" approach to estimate depth information of the ground plane. Like stereo cameras, they rely on ambient lighting, but are significantly less accurate due to the structure-from-motion approach. Lidar systems have their own active illumination and are therefore almost independent of ambient lighting. However, due to their time-dependent approach to depth estimation, with a resolution in the centimeter range, they are comparatively inaccurate and therefore not suitable for high-precision applications such as active suspension systems.

[0004] German patent application DE 10 2017 004 642 A1 discloses a method for determining the height profile of a road section ahead of a vehicle. In this method, data from the road section are acquired using at least one camera mounted on the front of the vehicle, and the height profile of the road section is determined by evaluating the acquired data. The method also provides for the road section ahead to be illuminated by a lighting unit. This lighting unit comprises at least one headlight of the vehicle, which projects at least one predefinable light pattern onto the road section. During the evaluation of the acquired data, a light pattern reflected from the road section is compared with the light pattern projected onto the road section.The elevation profile of the road section is determined based on a calculated difference between the reflected light pattern and the projected light pattern.

[0005] The object of the invention is to provide a means of enabling particularly reliable detection of uneven ground, thereby enabling safer driving, especially for semi-autonomous vehicles.

[0006] This problem is solved by means of a method with the features of claim 1 and by means of a detection system according to the invention. Advantageous embodiments of the system according to the invention are to be regarded as advantageous embodiments of the method according to the invention, wherein the means of the device are used to carry out the method steps. Furthermore, advantageous developments of the invention are described by the dependent claims, the following description, and the figures.

[0007] One aspect of the invention relates to a method for detecting unevenness in the road surface using a motor vehicle, in particular a passenger car, in which a plurality of method steps are provided.

[0008] In the first step of the process, the ground surface is illuminated by a light source, in particular a headlight, from the vehicle. The projection of the headlight beam serves as an active reference for the process.

[0009] Subsequently, a light-dark boundary is detected on the illuminated floor surface using at least one optical detection device.

[0010] Then, a first angle between the optical axis of the optical detection device and the beam direction of the light source, as well as a second angle between the optical axis of the optical detection device and a horizontal plane, are determined.

[0011] A new headlight angle is calculated based on the first angle, the second angle, and a measured time difference between the expected and the actual time of driving over a road surface irregularity.

[0012] This new headlight angle is stored as an initial value for future measurements.

[0013] Finally, the X and Z coordinates of a measuring point on the road are calculated based on the new headlight angle, the second angle and the known geometric properties of the vehicle to detect the road surface irregularities.

[0014] Unlike the approach known from the prior art, a method is presented that combines the advantages of an active system such as lidar with the accuracy of a triangulation method. The projection properties of the spotlights are used to measure ground irregularities using one or more cameras based on one or more light-dark boundaries and the triangulation principle.

[0015] In an advantageous embodiment of the invention, the light source is a headlight positioned at the front of the vehicle. This arrangement provides improved illumination of the road surface in front of the vehicle, thereby enabling, in particular, a clear detection of the light-dark boundary by the optical detection device. Furthermore, placing the headlight at the front of the vehicle improves the illumination of the roadway, thus enhancing, for example, the accuracy of road surface irregularity detection and increasing vehicle safety.

[0016] In a further advantageous embodiment of the invention, the optical detection device is a camera positioned at a suitable location within the vehicle to detect the light-dark boundary on the ground surface. The use of such a camera enables improved and reliable detection of the light-dark boundary and thus a more accurate determination of ground irregularities. Positioning the camera at a suitable location within the vehicle ensures that it has an improved viewing angle of the ground surface and is not obstructed by other vehicle components.

[0017] In a further advantageous embodiment of the invention, the time difference between the expected and the actual time the vehicle crosses a road surface irregularity is determined by means of chassis sensors. The use of chassis sensors enables particularly stable monitoring of the vehicle's condition while driving, including movements and road surface irregularities. By measuring the time difference with these sensors, the precise moment of crossing a road surface irregularity can be determined, leading to improved accuracy in the assessment of road surface irregularities.

[0018] In a further advantageous embodiment of the invention, the new headlight angle is calculated by means of an electronic computing device and an algorithm that takes into account the measured distance error and the current headlight angle. This electronic computing device enables rapid processing of the measurement data, and the application of a specially developed algorithm allows for efficient calculation of the new headlight angle.

[0019] In an advantageous embodiment of the invention, the X and Z coordinates of the measuring point on the road are determined by means of trigonometric calculations as a function of the headlight angle and the second angle. The use of this mathematical method thus enables a reliable implementation of the procedure.

[0020] In a further advantageous embodiment of the invention, the measured elevation values ​​along the light profile edge are stored at regular intervals in order to detect changes in the road's elevation profile. Regular storage of the elevation values ​​along the light profile edge enables continuous monitoring of the road's elevation profile. This allows for improved detection of changes such as unevenness in the road surface or gradients / slopes over time.

[0021] In a further advantageous embodiment of the invention, the stored elevation values ​​along the road profile edge are used for adjustments to the active suspension of the vehicle in order to react to rising or falling elevation values. By using this stored data, the vehicle's active suspension can react in real time to changes in the road's elevation profile.

[0022] In a further advantageous embodiment of the invention, the calculations and measurements for the continuous detection of road surface irregularities are performed in real time while driving. This enables the vehicle to react immediately to changing road conditions, thus providing a high level of driving comfort and improved driving stability.

[0023] Another aspect of the invention relates to a detection system for detecting road surface irregularities for a motor vehicle. The detection system comprises a light source for illuminating a surface on the vehicle, at least one optical detection device for detecting a light-dark boundary on the illuminated road surface, and an electronic computing device. This device is connected to the optical detection device and is configured to determine a first angle between an optical axis of the optical detection device and a beam direction of the light source, to determine a second angle between the optical axis of the optical detection device and a horizontal plane, and to calculate a new headlight angle as a function of the first angle, the second angle, and a measured time difference between the expected and the actual time of driving over a road surface irregularity.Furthermore, the computing device stores the new headlight angle as an initial value for future measurements and calculates the X and Z coordinates of a measuring point on the road based on the new headlight angle, the second angle and the known geometric properties of the vehicle.

[0024] Further advantages, features, and details of the invention will become apparent from the following description of a preferred embodiment and from the drawing. The features and combinations of features mentioned above in the description, as well as those mentioned below in the figure description and / or shown in the figure alone, can be used not only in the combinations specified, but also in other combinations or individually, without departing from the scope of the invention.

[0025] This shows: Fig. 1. A side view of a motor vehicle to illustrate the procedure.

[0026] Fig. Figure 1 shows a side view of a motor vehicle 10, illustrating a method for detecting unevenness in the road surface on a road 12 to be traveled by the motor vehicle 10 using a detection system 1 of the motor vehicle 10. The detection system 1 comprises an electronic computing device 20 for calculating all required values, which is electronically coupled with all other components.

[0027] The procedure for recording ground irregularities 11 on a road 12 comprises the following procedural steps: Illuminating the ground surface 16 by means of a light source 14 of the motor vehicle 10 and detecting a light-dark boundary on the illuminated ground surface 16 by means of at least one optical detection device 18. Determining a first angle a swbetween an optical axis 18a of the optical detection device 18 and a beam direction 14a of a light source 14 as well as a second angle α K between the optical axis 18a of the optical detection device 18 and a horizontal plane E. Calculating a new headlight angle α SWn depending on the first angle α SWn the second angle α K and a measured time difference Δt between the expected and the actual time of crossing the unevenness of the road surface 11. Saving the new headlight angle α SWn as an initial value for future measurements and subsequently calculating the X and Z coordinates of a measuring point on road 12 based on the new headlight angle α SWn , the second angle α K and the known geometric properties of the motor vehicle 10.

[0028] The method uses the projection of the spotlight as a light source 14, for example, its nearby light-dark boundary, to illuminate the ground surface 16. This constitutes the active reference, which ensures that the method also functions in darkness. However, other projection features of the spotlight can also be used, and for the regression of ground irregularities 11, for example, several light-dark boundaries can be used. With multiple references, however, these must be clearly distinguishable from one another. In the next step, at least one optical detection device or another camera ensures the detection of the light-dark boundary in the camera coordinate system.

[0029] The accuracy of the measurement method depends in particular on the determination of the two angles α. SW , and α KCrucial. For cameras aligned in the direction of travel, online vanishing point calibration is usually performed, so sufficient accuracy can be assumed. Headlight alignment is performed on many vehicles at the start of the journey; however, the accuracy for the position of the first light-dark boundary is often insufficient. Therefore, according to the invention, higher accuracy is achieved through an initial calibration. For this purpose, an initial value for α is used at the start of the journey. SW The distance to the ground irregularity 11 was measured and the expected crossing time t er The true crossing time t is determined using the chassis sensors. w The time difference Δt is determined and calculated. From the known driving speed v, the distance error Δs can now be calculated. Δs=Δt*v The distance error can be calculated. For example, if the speed varies during the measurement period, it can be determined from the speed integrated with respect to time as follows. The result also corresponds to the distance traveled. Here, t0 is defined as the starting point of the measurement and t1 as the endpoint. Δs=∫∫t0t1v(t)dt

[0030] This allows the new angle α to be determined. SWn calculate: aSWn=aSW+tanΔsZSW1−aSW+tanΔsZSW

[0031] This determination of the new headlight angle should take place shortly before the start of the journey, and the active suspension should not make any corrections during this time. The new headlight angle is advantageously saved as a new initial value at the end of the journey.

[0032] Ideally, the cameras' optical axes are mounted at a large angle to the headlight's beam direction and have high resolution within the projected field of view. The operating principle is illustrated in the following example by a schematic side view of a camera in the upper part of the windshield, first for a road surface without and then for one with a road surface irregularity. The measurement can be applied analogously in the horizontal plane.

[0033] For the calculation of the example measuring point, the values ​​in the Fig. The points, angles, and indices shown in Figure 1 are used.

[0034] According to this convention, the distance X is calculated MP in X-coordinates to the measuring point as follows: XMP=tan(αSW)*XSW+Zk−tan(αk)*Xk+Zktan(αSW)−tan(αk)

[0035] The height Z MP The measurement point in the street plane is calculated according to: ZMP=tan(αSW)*XSW+Zk−tan(αk)*Xk+Zktan(αSW)−tan(αk)*(−tan(αK))+Xk*tan(αk)+Zk

[0036] Advantageously, the measured altitude values ​​are stored along the edge of the light profile. This allows the temporal progression and thus the change in the altitude profile to be determined and transmitted to the active landing gear. This also makes it possible to detect and, if necessary, correct rising or falling altitude values ​​due to inclines or declines.

[0037] An incorrect assumption of the headlight angle leads to the correction of the chassis for uneven ground 11 occurring either too early or too late, resulting in an unwanted movement of the vehicle body.

[0038] This method makes it possible to measure points on the road surface with high accuracy using a camera, even in darkness. The method requires only a headlight and a camera, which are found in almost every modern vehicle. With current technology, even stereo camera systems cannot reliably estimate the road surface in the dark. QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] DE 10 2017 004 642 A1

[0004]

Claims

[1] Method for detecting unevenness of the ground (11) on a road (12) using a detection system (1) on a motor vehicle (10), comprising the following steps: - Illuminating the ground surface (16) by means of a light source (14) of the motor vehicle (10); - Detection of a light-dark boundary on the illuminated floor surface (16) by means of at least one optical detection device (18); - Determining a first angle (α SW ) between an optical axis (18a) of the optical detection device (18) and a beam direction (14a) of the one light source (14); - Determining a second angle (α K ) between the optical axis (18a) of the optical detection device (18) and a horizontal plane (E); - Calculating a new headlight angle (a SWn ) depending on the first angle (α SW ), the second angle (α K) and a measured time difference (Δt) between the expected and the actual time of crossing the road surface irregularity (11); - Saving the new headlight angle (α) SWn ) as an initial value for future measurements; - Calculating the X and Z coordinates of a measurement point on the road (12) based on the new headlight angle (α) SWn ), the second angle (α K ) and the known geometric properties of the motor vehicle (10). [2] Method according to claim 1, characterized by , that the light source (14) is a headlight located at the front of the motor vehicle (10). [3] Method according to claim 1 or 2, characterized by , that the optical detection device (18) is a camera which is arranged in a suitable position in the vehicle to detect the light-dark boundary on the ground surface (16). [4] Method according to any one of the preceding claims, characterized by, that the time difference (Δt) between the expected and the actual time of crossing the unevenness of the road is determined by means of chassis sensors. [5] Method according to any one of the preceding claims, characterized by , that the new headlight angle (α_SWn) is calculated by means of an electronic computing device (20) and an arranged algorithm that takes into account the measured distance error (Δs) and the current headlight angle (α_SW). [6] Method according to any one of the preceding claims, characterized by , that the X and Z coordinates of the measuring point on the road (12) are determined by means of trigonometric calculations depending on the headlight angle (α_SWn) and the second angle (α_K). [7] Method according to any one of the preceding claims, characterized by, that the measured elevation values ​​along the light profile edge are stored at regular intervals in order to record changes in the elevation profile of the road. [8] Method according to any one of the preceding claims, characterized by , that the stored altitude values ​​along the light profile edge are used for adjustments to the active chassis of the motor vehicle in order to react to rising or falling altitude values. [9] Method according to any one of the preceding claims, characterized by that the calculations and measurements for continuous recording of ground irregularities during the journey are carried out in real time. [10] Detection system (1) for detecting unevenness of the ground (11) on a road (12) for a motor vehicle (10), comprising a light source (14) for illuminating a ground surface (16) arranged on the motor vehicle (10), comprising at least one optical detection device (18) for detecting a light-dark boundary on the illuminated ground surface (16), comprising an electronic computing device connected to the optical detection device (18) and configured to determine a first angle (α_SW) between an optical axis (18a) of the optical detection device (18) and a beam direction (14a) of the light source (14), to determine a second angle (α_K) between the optical axis (18a) of the optical detection device (18) and a horizontal plane (E), and to calculate a new headlight angle (α_SWn) as a function of the first angle (α_SW).to calculate the second angle (α_K) and a measured time difference (Δt) between the expected and the actual time of crossing a road surface irregularity, to store the new headlight angle (α_SWn) as an initial value for future measurements, and to calculate the X and Z coordinates of a measurement point on the road (12) based on the new headlight angle (α_SWn), the second angle (α_K), and the known geometric properties of the vehicle (10).

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