Motor vehicle and self-calibration system for a motor vehicle's sensor system

Abstract

A motor vehicle with a vehicle body, as well as with at least one sensor system for detecting a vehicle environment, which is attached in the area of ​​an outside of the vehicle body, and with at least one electronic control unit that detects and evaluates lidar sensor data, is known. According to the invention, the lidar sensor is assigned a self-calibration system on the vehicle side, which has a vehicle-side alignment aid, and the lidar sensor is assigned a detection unit facing the alignment aid, which is coupled to the electronic control unit for the transmission of detection data, which processes deviations of a lidar coordinate system from a vehicle coordinate system and transforms them to the vehicle coordinate system. Use for passenger cars

Description

[0001] The invention relates to a motor vehicle according to the preamble of claim 1. The invention also relates to a self-calibration system according to the preamble of claim 11.

[0002] US 2020 / 0094677 A1 discloses a motor vehicle with a vehicle body and a sensor system behind a windshield near a vehicle roof. An alignment system has reflective alignment markings that are detected and processed in an electronic control unit to calculate deviations of a sensor coordinate system from a vehicle coordinate system and transform them to the vehicle coordinate system.

[0003] A similar self-calibration system is also known from US 2017 / 0336496 A1, which is provided with markings that can be reflected in order to be detected by a radar device.

[0004] Passenger cars that use lidar sensors to detect the vehicle's surroundings are well known. These lidar sensors are embedded in or attached to the exterior of a vehicle body. The lidar sensors can either be recessed into the vehicle body, extending outward only when in use, or they can be permanently mounted on the vehicle. To ensure accurate measurements and detection of the vehicle's surroundings, the lidar sensors must be precisely aligned to the vehicle's axles and thus to the vehicle's coordinate system. Adjustments made at the factory upon completion of a new vehicle are no longer valid if subsequent body repairs are required or if production-related tolerances result in a deviation from the target position.Often, an offset of the lidar sensors relative to the vehicle coordinate system occurs, which affects the accuracy of the data transmitted from the lidar sensors to a vehicle control system.

[0005] The object of the invention is to provide a motor vehicle and a self-calibration system of the type mentioned at the outset, which enable a consistent accuracy of the detection of the vehicle environment by the at least one sensor system using simple means.

[0006] This object is achieved for the motor vehicle by the features of claim 1. The at least one sensor system is preferably a lidar sensor system. The at least one sensor system can also be embodied as a radar, ultrasound, or camera sensor system. The lidar sensor system can have one or more lidar sensors. The lidar sensors can be designed as solid-state sensors or as mechanically rotating sensors. In the latter case, a mirror rotates in a housing, whereby correspondingly pulsating laser beams are deflected. The detection unit can be part of the sensor system, in particular the lidar sensor system. Alternatively, the detection unit can be a sensor unit separate from the sensor system, in particular the lidar sensor system, such as in particular a camera, which is provided directly adjacent to the lidar sensor system or as a structural unit with the lidar sensor system.The separate sensor unit is advantageously mounted on the same support structure as the lidar sensor system in order to be integrated into the lidar coordinate system like the lidar sensor system. The solution according to the invention is particularly advantageous for passenger cars. The solution according to the invention is equally suitable for trucks or commercial vehicles. The solution according to the invention is particularly suitable for motor vehicles on land. However, the solution according to the invention can also be used for motor vehicles on water. Because the lidar sensor system, in conjunction with the electronic control unit, performs self-calibration relative to the vehicle coordinate system, complex adjustments for aligning the lidar sensor system relative to the vehicle are unnecessary. Existing deviations between the lidar coordinate system and the vehicle coordinate system are recorded and converted to the vehicle coordinate system.

[0007] According to the invention, the alignment aid is designed as a physical alignment structure fixed to the vehicle, spaced relative to the sensor system, in particular the lidar sensor system, towards a vehicle center, which has structural segments that are spatially offset from one another and aligned in alignment with the vehicle coordinate system. The alignment structure is offset inwards towards the vehicle center relative to the lidar sensor system arranged in the area of ​​the outer side of the vehicle body and is positioned fixed to the vehicle. Due to the structural segments that are spatially offset from one another within the vehicle coordinate system, any non-aligned detection of the alignment structure allows a conclusion to be drawn about the offset or the rotation relative to the vehicle coordinate system. The alignment structure preferably has bar segments as structural segments that are arranged along the three spatial axes of the vehicle coordinate system, i.e.are aligned along a vehicle longitudinal axis, along a vehicle transverse axis or along a vehicle vertical axis, or are positioned offset in depth relative to one of these vehicle axes.

[0008] In a further embodiment of the invention, the alignment structure comprises at least one cross as a structural segment. The cross can be designed as a simple cross-shaped beam with orthogonally aligned beams or as a double cross-shaped beam with parallel, spaced-apart beam segments.

[0009] In a further embodiment of the invention, the cross is formed by several crossbeam sections that are spatially offset from one another—relative to a rear side of the sensor system, in particular the lidar sensor system—with respect to alignment. Preferably, a double crossbeam structure is provided, the crossbeam sections of which are at least partially offset from one another in depth toward the center of the vehicle.

[0010] In a further embodiment of the invention, a one-piece cross is provided, which is arranged spatially offset behind a square frame of the alignment structure, relative to a rear side of the sensor system, in particular the lidar sensor system. The alignment structure consists of the square frame and the one-piece cross, which is offset parallel to the rear in depth. The cross is aligned concentrically with a center point of the square frame, in alignment with the rear side of the lidar sensor system.

[0011] In a further embodiment of the invention, the lidar sensor system comprises a housing having a passage on a rear side facing the alignment aid, through which light waves from the lidar sensor system can detect the alignment aid. This embodiment is particularly advantageous for a mechanical lidar sensor system equipped with a rotating mirror to enable a 360° deflection of the laser beams. The passage forms a window through which the light waves of a pulsating laser can also exit to the rear, i.e., away from the outside of the vehicle body, in order to detect the alignment aid.

[0012] In a further embodiment of the invention, the alignment structure is equipped with light segments, in particular LEDs. The detection unit is advantageously designed as a camera positioned adjacent to the sensor system, in particular the lidar sensor system, and directed toward the alignment structure. If the alignment structure is equipped with the light segments, the camera can easily detect the alignment structure, since the light segments emit corresponding light beams that can be detected by the camera.

[0013] In a further embodiment of the invention, the control unit is assigned an electronic data processing device that has a memory in which a target orientation of the sensors, in particular the lidar sensors, relative to the vehicle coordinate system is stored. The target orientation of the lidar sensors is intended to be aligned, i.e., coaxial, with the vehicle coordinate system.

[0014] In a further embodiment of the invention, vehicle coordinates of the vehicle-mounted alignment aid are stored in the memory. Thus, the dimensions of the vehicle-mounted alignment structure and the coordinate data relative to the vehicle coordinate system are available in the memory.

[0015] In a further embodiment of the invention, the data processing device is designed such that sensor data from the sensor system, in particular the lidar sensor system, relating to the vehicle's surroundings is converted to the vehicle coordinate system in real time. The data processing device records the sensor data as actual data, compares it with the target data stored in memory, and uses this to calculate the actual alignment of the lidar sensor system. Deviations between the target alignment of the lidar sensor system and the actual alignment of the lidar sensor system are taken into account when evaluating the sensor data, so that the sensor data provided by the lidar sensor system ensures an exact representation of the vehicle's surroundings relative to the vehicle body.

[0016] For the self-calibration system of the type mentioned at the outset, the problem underlying the invention is solved by the features of claim 11.

[0017] Further advantages and features of the invention emerge from the claims. Preferred embodiments of the invention are described below and illustrated with reference to the drawings. Fig. 1 shows schematically a front section of an embodiment of a motor vehicle according to the invention, Fig. 2 shows an enlarged perspective view of a lidar sensor together with a vehicle-mounted alignment aid as a self-calibration system, Fig. 3 the order pursuant to Fig. 2 in perspective view diagonally from behind, Fig. 4 a front view of a housing of the lidar sensor according to the Fig. 2 and Fig. 3, Fig. 5 schematically shows a top view of the lidar sensor system according to the Fig. 1 to 4, Fig. 6 a front view of the alignment aid for the lidar sensors according to Fig. 2 and Fig. 3, Fig. 7 schematically shows a front view of another embodiment of a motor vehicle according to the invention, Fig. 8 schematically shows an enlarged view of a lidar sensor system of the motor vehicle according to Fig. 7 together with a further self-calibration system according to the invention for adjusting the alignment of the lidar sensor system relative to a vehicle coordinate system of the motor vehicle according to Fig. 7 and Fig. 9 shows a perspective view of the alignment aid for the lidar sensors according to Fig. 8.

[0018] A motor vehicle 1 in the form of a passenger car has, according to Fig. 1 in a front area of ​​a vehicle body, in this case in a central area of ​​a front bumper, a lidar sensor system 2 in order to detect the vehicle's front surroundings. The lidar sensor system 2 is designed as a mechanical lidar sensor in which a mirror rotates 360° inside a housing 3 in order to deflect pulsating laser beams. The housing 3 represents a housing for the lidar functional components. In the illustrated embodiment, the housing 3 is mounted fixedly to the vehicle on the front bumper. In an embodiment of the invention not shown, the lidar sensor system is recessed in an outer skin of the vehicle body, so that the lidar sensor system must be moved outwards from the outer skin of the vehicle body in order to detect the vehicle's surroundings.

[0019] The lidar sensor system 2 is assigned an electronic control unit S, which is coupled to a central vehicle control system F in order to be able to use processed sensor data in vehicle functions, such as, in particular, displaying the vehicle's surroundings on at least one screen or for further processing in a control unit for autonomous driving. To enable accurate detection of the vehicle's surroundings relative to the exterior of the vehicle body, the lidar sensor system 2 must be precisely coordinated with a vehicle-side coordinate system K1. The vehicle-side coordinate system K1 defines a vehicle axis system with a longitudinal axis, a transverse axis, and a vertical axis.

[0020] As shown by the Fig. 2, the lidar sensor system 2 defines a lidar coordinate system K2, which ideally corresponds to this vehicle coordinate system K1 when the housing 3 is exactly aligned to the vehicle coordinate system K1.

[0021] According to the invention, such a mechanical alignment is not required. This is because the lidar sensor system 2 is assigned an alignment aid 4 in the form of a mechanical alignment structure, which is mounted in a vehicle-fixed manner in the area of ​​a body support structure within an outer skin of the vehicle body. The alignment aid 4 is mounted in a vehicle-fixed manner at a distance behind the lidar sensor system 2, in this case offset inwardly along the vehicle's longitudinal axis towards the vehicle center. As can be seen from the Fig. 3 to 6, the alignment aid 4 forms a double cross beam, with individual beam segments being offset backwards in the vehicle's longitudinal direction. This can be seen from the Fig. 2 as well as the Fig. 3 clearly visible.

[0022] The housing 3 of the lidar sensor 2 has a passage 5 in the form of a rectangular window in the area of ​​its rear side, through which the lidar sensor 2 can also detect objects on the rear side of the housing 3. The detection range of the lidar sensor 2, both at the front and the rear, is determined by the Fig. 5 is clearly visible. The alignment aid 4 in the form of a double cross beam with the beam segments offset in depth can be detected by the correspondingly pulsating laser beams of the lidar sensor 2, since the alignment aid 4 is positioned within the detection range of the passage 5 on the rear side of the housing 3. If the housing 3 is precisely aligned relative to the vehicle-mounted alignment aid 4, the alignment aid 4 is aligned according to the Fig. 4 and Fig. 6 as a double cross beam with beam segments that are exactly flush with one another. As soon as the housing 3 is slightly rotated about a vehicle's longitudinal axis and / or offset about a vehicle's vertical axis and / or about a vehicle's transverse axis, the beam segments of the alignment aid 4 are no longer exactly aligned, but rather rotated or offset from one another by the laser beams of the lidar sensor system 2. This is detected by the data processing device assigned to the control unit S. A target alignment of the lidar sensor system 2 with respect to the vehicle coordinate system K1 is stored in the data processing device. The target alignment is designed such that the lidar coordinate system K2 is identical to the vehicle coordinate system K1.The data processing device of the control unit S detects corresponding deviations along all spatial axes, allowing the data processing device to calculate an exact transformation of the acquired sensor data from the lidar sensor system 2 to the vehicle coordinate system. This enables an exact reproduction of the vehicle environment relative to the vehicle body via the vehicle control unit F, in particular for displaying the vehicle environment on a screen in the vehicle interior or for use in a control unit for autonomous driving.

[0023] In the embodiment according to the Fig. 7 to 9, a motor vehicle 1a in the form of a passenger car also has a lidar sensor system 2a on the front of a vehicle body, which, however, is provided with a lidar sensor system 2a in comparison to the embodiment according to the Fig. 1 to 6 is designed differently. The lidar sensor 2a is designed as a solid-state lidar sensor. The solid-state lidar sensor 2a is based on semiconductor technology and has no freely moving mechanical parts. The lidar sensor 2a is designed according to Fig. 8 is attached to a vehicle-mounted support part T, which is integrated in a front bumper in a fixed or movable position. Directly adjacent and above the lidar sensor system 2a, a detection unit 6 in the form of a camera is provided, which is also mounted on the support part T in a vehicle-mounted manner. The function of this detection unit 6 is described below.

[0024] The detection unit 6 in the form of a camera serves to detect the positioning of an alignment aid 4a, which is analogous to the double cross beam according to the Fig. 1 to 6 is also mounted on the vehicle side at a distance behind the lidar sensor 2a. In the embodiment according to the Fig. 1 to 6, the function of detecting the alignment aid 4 was performed by the light waves of the lidar sensor 2 passing through the passage 5 at the rear. In the embodiment described here according to the Fig. 7 to 9, however, the detection is carried out by the separate detection unit 6 in the form of the camera. The alignment aid 4a is designed differently from the alignment aid 4 of the embodiment according to the Fig. 1 to 6. As can be seen from the Fig. 8 and Fig. 9, the alignment aid 4a comprises, on the one hand, a rectangular frame 7 fixed to the vehicle, which defines a rectangular window. On the other hand, the alignment aid 4a comprises a point-symmetrical cross-beam 8, which is arranged in the vehicle longitudinal direction at a distance behind the window of the frame 7. Thus, the cross-beam 8 is analogous to the individual beam segments of the alignment aid 4 according to the Fig. 1 to 6 are also arranged offset in the vehicle's longitudinal direction relative to the frame 7. The dimensions of the crossbeam 8 are matched to the dimensions of the rectangular window of the frame 7, so that when aligned exactly along a vehicle's longitudinal axis of the vehicle coordinate system K1, the crossbeam 8 fits exactly into the window of the frame 7 when viewed from the front. The detection unit 6 in the form of the camera detects this arrangement of frame 7 and crossbeam 8. If the assembly comprising the detection unit 6, support part T and lidar sensor 2a is offset relative to the alignment aid 4a, the detection unit 6 also detects an offset image of the alignment aid 4a, so that the window of the frame 7 and the crossbeam 8 are no longer exactly aligned with each other. This is done analogously to the previously described embodiment according to the Fig. 1 to 6 via a data processing device of a control unit S aThe LiDAR sensor 2a is processed and evaluated. The control unit S a is equipped with a vehicle control F a coupled in order to operate in an analogous manner to the embodiment according to the Fig. 1 to 6 correspondingly transformed calculation data to the vehicle control F a Even in the case of the embodiment according to the Fig. 7 to 9 are stored in a memory of the data processing device S a The vehicle coordinates of the alignment aid 4a are stored relative to the vehicle coordinate system K1 in the same way as data of a target alignment of the detection unit 6 and the lidar sensor system 2a. The data processing device of the control unit S athus detects any spatial offset of the lidar sensor 2a relative to the alignment aid 4a and transforms this offset to the vehicle coordinate system, so that the vehicle environment detected by the lidar sensor 2a is precisely matched to the outer contours of the vehicle body by the vehicle control F a can be processed.

[0025] The alignment aid 4a according to the Fig. 8 and Fig. 9 can be equipped with light segments, in particular in the form of LEDs distributed over the surfaces of the frame 7 and the cross beam 8, for better detection by means of the detection unit 6 designed as a camera.

Claims

[1] Motor vehicle (1, 1a) with a vehicle body, and with at least one sensor system, in particular a lidar sensor system (2, 2a), for detecting a vehicle environment, which is mounted in the region of an outer side of the vehicle body, and with at least one electronic control unit (S, S a ), which records and evaluates sensor data, in particular Lidar sensor data, wherein the sensor system, in particular the Lidar sensor system (2, 2a), is assigned a self-calibration system on the vehicle side, which has a vehicle-side alignment aid (4, 4a), and wherein the sensor system, in particular the Lidar sensor system (2, 2a), is assigned a detection unit (6) facing the alignment aid (4, 4a), which is used for the transmission of detection data to the electronic control unit (S, S a) which processes deviations of a sensor coordinate system, in particular a lidar coordinate system (K2), from a vehicle coordinate system (K1) and transforms them to the vehicle coordinate system (K1), characterized by that the alignment aid (4, 4a) is designed as a vehicle-fixed physical alignment structure which is spaced apart from the sensor system, in particular the lidar sensor system (2, 2a), towards a vehicle center and which has spatially offset structural segments which are aligned in alignment with the vehicle coordinate system (K1) [2] Motor vehicle (1, 1a) according to claim 1, characterized by that the alignment structure has at least one cross as a structural segment. [3] Motor vehicle (1) according to claim 2, characterized by that the cross is formed by several crossbeam sections which - with respect to an alignment with a rear side of the sensor system, in particular the lidar sensor system (2) - are arranged spatially offset from one another. [4] Motor vehicle (1a) according to one of claims 1 or 2, characterized by that a one-piece cross (8) is provided which - with respect to an alignment to a rear side of the sensor system, in particular the lidar sensor system (2a) - is arranged spatially offset behind a square frame (7) of the alignment structure. [5] Motor vehicle (1) according to one of claims 1 to 3, characterized by that the lidar sensor system (2) has a receiving housing (3) which has a passage (5) on a rear side facing the alignment aid (4), through which light waves of the lidar sensor system (2) can detect the alignment aid (4). [6] Motor vehicle (1, 1a) according to one of the preceding claims, characterized by that the alignment structure is equipped with light segments, in particular LEDs. [7] Motor vehicle (1a) according to claim 4 or 6, characterized bythat the detection unit (6) is designed as a camera which is positioned adjacent to the sensor system, in particular the lidar sensor system (2a), and is directed towards the alignment structure. [8] Motor vehicle (1, 1a) according to one of the preceding claims, characterized by that the control unit (S, S a ) is assigned an electronic data processing device which has a memory in which a desired orientation of the sensor system, in particular the lidar sensor system (2, 2a), relative to the vehicle coordinate system (K1) is stored. [9] Motor vehicle (1, 1a) according to claim 8, characterized by that vehicle coordinates of the vehicle-fixed alignment aid (4, 4a) are stored in the memory. [10] Motor vehicle (1, 1a) according to claim 8 or 9, characterized bythat the data processing device is designed such that sensor data of the sensor system, in particular the lidar sensor system (2, 2a), with regard to the vehicle environment are converted in real time to the vehicle coordinate system (K1). [11] Self-calibration system for a sensor system, in particular a lidar sensor system (2, 2a), of a motor vehicle, with an alignment aid (4, 4a) that can be mounted on the vehicle and with a detection unit assigned to the sensor system, in particular the lidar sensor system (2, 2a), which is facing the alignment aid (4, 4a), and with an electronic control unit (S, S a), which, on the basis of the data transmitted by the detection unit for positioning the alignment aid (4, 4a), processes deviations of a sensor coordinate system, in particular a lidar coordinate system (K2), from a vehicle coordinate system (K1) and transforms them to the vehicle coordinate system (K1), wherein the alignment aid (4, 4a) is designed as a physical alignment structure fixed to the vehicle, spaced apart from the sensor system, in particular the lidar sensor system (2, 2a), towards a vehicle center, which has structural segments which are spatially offset from one another and aligned in alignment with the vehicle coordinate system (K1).

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