DE102008010805A1 - Calibration plate arranging device for motor vehicle, has holding device allowing vertical and horizontal adjustment and fixing calibration plate, and objective device for aligning calibration plate with respect to vehicle camera system - Google Patents

Abstract

The device has a holding device (16) formed such that the holding device allows vertical and horizontal adjustment and fixes a calibration plate (12). An objective device (18) is provided for aligning the calibration plate with respect to a vehicle camera system. The holding device exhibits a bivalent mount (20) with two freedom degrees for holding the calibration plate, such that the calibration plate adjusts independently horizontally and vertically due to the gravitation. Two spirit levels ate provided for the horizontal and vertical adjustment of the calibration plate. An independent claim is also included for a method for arranging a calibration plate.

Description

The The invention relates to a device and a method for arranging a calibration board in front of a vehicle camera system according to claim 1 or 9.

For driver assistance systems In vehicles increasingly camera systems are installed, which the Capture surroundings in front of and behind a vehicle and if possible exactly, d. H. reproduce true to scale should. When a camera is used to measure objects in their environment is used as possible a "distortion-free" picture of the environment important. Therefor As a rule, a calibration of a camera is performed, in particular using a camera model or imaging model of a camera system, that in a control unit can be installed.

Around To create such a model, it is required that model parameters of the camera system are known. When such model parameters act For example, it is a position, a mounting position or a mechanical or optical design of the camera system. These model parameters will be usually determined in a calibration process. In the model parameters is distinguished between extrinsic and intrinsic parameters. extrinsic Parameters are, in particular, all parameters which determine the installation position and describe the position of the camera system. Describe intrinsic parameters system-internal parameters of the imaging system.

There the extrinsic parameters due to the installation position and orientation of the camera system, they can not be pre-determined be determined by the camera manufacturer, but only after installation of the camera system. For camera systems in vehicles this means that this determination of extrinsic camera parameters (camera calibration) partly also in motor vehicle workshops / customer service carried out must become. For this purpose, usually a calibration board, d. H. a blackboard with a calibration pattern used in front of the vehicle is placed. Using the image generated by the camera Calibration panel can then, for example, by an algorithm, which is implemented in the camera system, the installation position and orientation determined by the camera.

Fewer use computationally expensive methods to determine the extrinsic camera parameters These algorithms are based on the use of the "vanishing point method." These have the advantage that they are implemented in the camera system itself can and without the use of extensive imaging models in the Get by calibration. However, these methods are sensitive with respect to the positioning of the calibration pattern, as with larger deviations the optical axis of the calibration pattern the coupling of the attitude angle becomes relevant, but without complete picture model be taken into account can. The positioning of the calibration board is thus at this Approach a special role too. In particular, the plays Distance between panel and camera and the mounting height of the camera above the footprint an important role. However, these parameters are mainly in the workshops difficult to determine and require an increased workload. As well the alignment of the calibration plate is a time-consuming step.

task The present invention is therefore an apparatus and a To suggest a method of arranging a calibration board in front of a vehicle camera system, a simple and robust calibration of a vehicle camera system enable.

These The object is achieved by a device for arranging a calibration board in front of a vehicle camera system having the features of claim 1 and a corresponding method with the features of claim 9 solved. Further embodiments of the invention will become apparent from the dependent claims.

One essential idea of the invention is that as possible accurately placing a calibration board in front of a vehicle camera system an easy-to-use holding device with a target device is provided for aligning the calibration board. With the aiming device may be the calibration board in relation to a vehicle camera system to be calibrated to be finely aligned while the holding device for roughly aligning and fixing the calibration board serves. This is a simple and robust calibration of a vehicle camera system for example, in a car repair shop allows.

• – einer Haltevorrichtung für die Kalibriertafel, wobei die Haltevorrichtung derart ausgebildet ist, dass sie eine vertikale und horizontale Justage und Fixierung der Kalibriertafel ermöglicht, und
• – einer Zielvorrichtung, die zum Ausrichten der Kalibriertafel in Bezug auf das Fahrzeug-Kamerasystem vorgesehen ist.

The invention now, according to one embodiment, relates to a device for arranging a calibration panel in front of a vehicle camera system

• - A holding device for the calibration board, wherein the holding device is designed such that it allows a vertical and horizontal adjustment and fixation of the calibration board, and
• A target device provided for aligning the calibration board with respect to the vehicle camera system.

According to a further embodiment of the invention, a first spirit level for horizontal adjustment of the calibration board and a second spirit level for vertical adjustment of the calibration panel may further be provided, whereby the adjustment erleich can be tert.

In an embodiment the invention, the holding device with a divalent bearing have two degrees of freedom for holding the calibration board, so that the calibration board automatically becomes horizontal due to gravity and can adjust vertically. As a result, the adjustment is also substantially simplified, since essentially no manual intervention to adjust the calibration board horizontally and vertically is.

Farther can according to a embodiment the invention, the target device comprise a laser pointer, the be aligned according to the adjustment of the calibration board can and is arranged such that a radiated from him Laser beam in the direction of the vehicle camera system runs. Thereby can be inexpensive an adjustment with high precision be achieved with ease of handling at the same time. With the Laser pointers, especially the fine adjustment is much easier.

The Target device can according to a embodiment the invention also includes a leveling device (rear sight and grit), which allows an adjustment of the calibration board. Such a target device has the advantage of being without electrical power gets along and cheaper as, for example, a laser pointer can be implemented.

The Holding device can according to a embodiment the invention of a stand comprise, on which the calibration panel by means of a locking device can be fixed. The stand can be inexpensive produced, for example from a simple metal bar, which are mounted on one foot is that with rollers for easy operation of the entire device can be provided.

Further can according to a Embodiment of Invention, the locking device be designed such that The calibration board is thus rotatably mounted on the stand for horizontal adjustment can be. Such a locking device can be simple and economical be implemented and enabled an independent one Horizontal alignment of the calibration board due to gravity.

The Locking device can according to one embodiment The invention further be designed such that the calibration board so that it can be rotatably mounted on the stand for vertical adjustment.

• – Positionieren der Vorrichtung nach der Erfindung vor dem Fahrzeug-Kamerasystem,
• – mittiges Ausrichten der Vorrichtung vor dem Fahrzeug-Kamerasystem,
• – horizontale und vertikale Justage der Kalibriertafel mittels der Haltevorrichtung zum groben Ausrichten der Kalibriertafel in Bezug auf das Fahrzeug-Kamerasystem, und
• – vertikales und horizontales Ausrichten der Kalibriertafel mittels der Zielvorrichtung derart, dass sich die Kalibriertafel exakt auf der Höhe des Fahrzeug-Kamerasystems und mittig zu diesem befindet.

The invention provides, according to a further embodiment, a method for arranging a calibration panel with a device according to the invention in front of a vehicle camera system with the following steps:

• Positioning the device according to the invention in front of the vehicle camera system,
• Central alignment of the device in front of the vehicle camera system,
• - Horizontal and vertical adjustment of the calibration board by means of the holding device for coarse alignment of the calibration board with respect to the vehicle camera system, and
• - Vertical and horizontal alignment of the calibration board by means of the aiming device such that the calibration board is located exactly at the level of the vehicle camera system and in the middle of this.

This For example, the method can be used in a controller for a fully automatic Calibration panel assembly device can be implemented which the device according to the invention comprises. For example, can a vehicle in front of such a calibration board arrangement device be positioned in a workshop, and then can the automatic process of arranging and aligning the calibration board is started relative to a camera system of the vehicle become. The fine alignment of the calibration board can be, for example be done manually by a service person using Help the target device of the device according to the invention a possible makes exact alignment. It is also conceivable an automatic Fine alignment by a corresponding adjustment device.

Further Advantages and applications The present invention will become apparent from the following description in conjunction with the embodiments illustrated in the drawings.

In the description, in the claims, in the abstract and in the drawings are those in the listed below List of reference symbols used terms and associated reference numerals used.

The Drawings show in

1 the image of a calibration pattern of a calibration board, which was taken with a camera of a vehicle camera system and without knowing the exact position of the calibration board allows the determination of the orientation of the camera in the vehicle;

2 a top view of a vehicle with a built-in camera system and a centrally located in front of the vehicle calibration panel for determining the orientation of the camera system;

3 a side view of a vehicle with a vehicle camera system and a device for arranging the calibration board in front of a vehicle camera system according to the invention; and

4 Detail views of two embodiments of the calibration board holding device of the device for arranging the calibration board in front of a vehicle camera system according to the invention.

in the Following can identical and / or functionally identical elements with the same reference numerals be provided. In the context of the present invention description the terms camera and camera system are used interchangeably.

to Determination of the aforementioned extrinsic parameters of a vehicle camera system must be after the current state of the art relatively expensive the position of a Calibration panel can be determined to the vehicle to the installation orientation to determine the camera. In particular, this always plays the distance Board to camera and installation height the camera over the footprint of the Vehicle an important role. However, these parameters are particular in workshops and difficult to identify in customer service and require one increased Workload. Likewise, the orientation of the calibration board is on time-consuming operation, by the present invention shortened shall be.

• – Die Kalibriertafel ist mittig vor dem Fahrzeug ausgerichtet.
• – Die Kalibriertafel ist auf der gleichen Höhe wie die Kamera.
• – Die Kalibriertafel steht senkrecht auf der Fahrzeuglängsachse (vertikale Ausrichtung).
• – Die Kalibriertafel ist horizontal ausgerichtet.

A calibration method for a vehicle camera system therefore essentially requires the following:

• - The calibration board is centered in front of the vehicle.
• - The calibration board is at the same height as the camera.
• - The calibration board is perpendicular to the vehicle's longitudinal axis (vertical orientation).
• - The calibration board is aligned horizontally.

This makes it possible to determine the orientation of the camera in the vehicle without the knowledge of the position of the board, by the deviation of the calibration pattern in the in 1 shown image is evaluated by the optical axis. 1 Figure 12 also shows those for determining the pitch angle (yaw) and roll angle (roll) of the camera from the deviation of the calibration pattern X _P1 , Y _P1 , X _P2 , Y _P2 in the image of the camera from the optical axis X _OA , Y _OA used formulas. Further parameters of the formulas are the pixel size of the camera image and the focal length of the optics used in the camera for imaging the calibration pattern of the calibration tablet by means of the camera.

In order to be able to calculate the installation orientation of the camera in the vehicle independently of the distance of the calibration panel, the panel should be positioned as exactly as possible in front of the vehicle at the height of the camera, as shown in 2 in a plan view from above on a vehicle 13 is shown, in front of the center and perpendicular to the vehicle longitudinal axis 15 the calibration board 12 with the in 1 arranged calibration pattern is arranged. Take the blackboard 12 this position in front of the vehicle 13 on, the distance calibration board plays 12 to camera 14 and installation height of the camera 14 not a factor and is not included in the calculation of the pitch angle. A complex measurement of these two sizes is thus eliminated. It is also sufficient for a central installation of the camera 14 in the vehicle 13 , the 12 Board in the middle in front of the vehicle 13 to position the yaw angle of the camera 14 to investigate. The distance of the blackboard 12 to the camera 14 is not included in the calculation, the central positioning of the board 12 can with the help of body features of the vehicle 13 respectively. The roll angle can be calculated directly by the evaluation of the calibration pattern, if this is aligned horizontally.

3 shows in a side view of the vehicle 13 and the camera system installed in it 14 in that one is arranged in the area of the rearview mirror on the windshield of the vehicle. In front of the vehicle is a device 10 for placing a calibration board 12 set up according to the invention. The device 10 has a holding device 16 on top of a stand 22 in the form of a rod which is mounted on a movable lower part. The calibration board 12 is on the stand 22 by means of a bivalent bearing 20 attached, whose function will be explained later in more detail. In 3 is the device 10 with the calibration board 12 shown almost optimally arranged, since the calibration board at the height of the vehicle camera system 14 located and also in the middle as in 2 aligned with the camera system.

4 shows two embodiments of the holder of the calibration board 12 on the stand 22 the holding device 16 in detail. On the left an embodiment is shown in which the holding device 16 a divalent camp 20 that has the calibration board 12 holds and a relatively free Verschenkbarkeit the calibration board 12 allowed for horizontal and vertical alignment. As mentioned above, this means that the vertical orientation means that the normal through the calibration board 12 spanned plane parallel to the vehicle longitudinal axis or to a flat surface. The horizontal orientation means that the lower edge of the calibration board 12 runs parallel to the flat ground. To ensure this is the bivalent bearing 20 placed at the center of the top of the calibration board, so that the calibration board weight symmetrical at the divalent bearing 20 is attached and can independently orient by gravity so that the demand for horizontal and vertical alignment can be easily met. The height of the calibration board can be adjusted by moving the locking device 24 For example, a sliding carriage with a clamping screw, the bivalent bearing 20 on the stand 22 be set. The right in 4 illustrated embodiment shows a pivot bearing 21 the calibration board 12 , which is a self-contained horizontal alignment of the calibration board 12 allowed due to gravity. This storage 21 is easier than a divalent bearing 20 constructed, but does not allow vertical independent alignment of the calibration board 12 ,

Assuming that the vehicle 13 with the camera to be measured 14 standing on a flat footprint, the fine alignment of the calibration board can be 12 without additional measuring / auxiliary means, by a laser pointer perpendicular to the calibration panel surface 18 (please refer 4 , left-hand illustration) is centered on the calibration pattern. With this it is possible the blackboard 12 to the camera system 14 in accordance with the requirements of the calibration procedure.

• 1. Die Kalibriertafel 12 ist an einem Ständer 22 befestigt, dieser wird mit Hilfe von Karosseriemerkmalen (Kühlergrill, Kühlerfigur/-logo, etc.) mittig vor dem Fahrzeug 13 ausgerichtet.
• 2. Die Kalibriertafel 12 ist vertikal mit Hilfe einer Wasserwaage ausgerichtet, so dass der Strahl 26 des Laserpointers 18 horizontal verläuft. Der Laserpointer 18 wird auf die Höhe des Kamerasystems 14 gebracht, indem die Tafel 12 am Ständer 22 so lange vertikal verschoben wird bis der Laserpointer exakt mittig auf das Objektiv des Kamerasystems 14 zeigt. Da die Tafel 12 senkrecht ausgerichtet ist und der Laserstrahl 26 senkrecht auf der Tafelfläche steht, ist damit wie vom Kalibrierverfahren gefordert die Kalibriertafel 12 exakt auf derselben Höhe wie das Kamerasystem 14.
• 3. Ist der Laserpointer 18 auf das Kamerasystem 14 ausgerichtet und ist der Ständer 22 der Kalibriertafel 12 mittig vor dem Fahrzeug, so ist damit auch die Kalibriertafelfläche senkrecht zur Fahrzeuglängsachse 15 ausgerichtet!
• 4. Die Kalibriertafel 12 kann mit Hilfe einer Wasserwaage horizontal ausgerichtet werden.

The process of alignment will be explained below. On the 3 and 4 Reference is made:

• 1. The calibration board 12 is on a stand 22 fastened, this is with the help of body features (grille, radiator figure / logo, etc.) in the center in front of the vehicle 13 aligned.
• 2. The calibration board 12 is aligned vertically by means of a spirit level, so that the beam 26 of the laser pointer 18 runs horizontally. The laser pointer 18 is at the height of the camera system 14 brought by the chalkboard 12 on the stand 22 is moved vertically until the laser pointer is exactly centered on the lens of the camera system 14 shows. Since the blackboard 12 is aligned vertically and the laser beam 26 is perpendicular to the table surface, so is as required by the calibration process, the calibration board 12 exactly at the same height as the camera system 14th
• 3. Is the laser pointer 18 on the camera system 14 aligned and is the stand 22 the calibration board 12 centered in front of the vehicle, so is the calibration panel perpendicular to the vehicle's longitudinal axis 15 aligned!
• 4. The calibration board 12 can be aligned horizontally with the help of a spirit level.

The laser pointer 18 Aligns the calibration board with the camera system 14 , Alternatively, a leveling device (rear sight and grit) can be used to align the panel. The advantage here is that it is a passive element. There are no hazards associated with the use of a laser. Furthermore, no electrical power is needed.

is the calibration board is positioned accordingly, so there is no measurement with additional measuring equipment necessary! The board aligns itself horizontally and vertically out, from the service staff is only the panel in the middle in front of the vehicle and over set up the leveling device to the height of the camera. A correct alignment of the panel on the vehicle is thus very robust, feasible without further aids and less error-prone.

• • Eine Vermessung der Kalibriertafelposition ist zur Bestimmung der Einbauorientierung der Kamera nicht mehr notwendig.
• • Die Einstellung der Kalibriertafelhöhe auf die Höhe der Kamera ist ohne weitere Messwerkzeuge möglich.
• • Die laterale Positionierung der Tafel kann über Karosseriemerkmale erfolgen.
• • Die Kalibriertafel kann sich bei Ausführungsformen der Erfindung von alleine horizontal und vertikal ausrichten, wodurch eine Fehlausrichtung nahezu ausgeschlossen werden kann!

In summary, the invention has the following advantages in particular:

• • A calibration table position measurement is no longer necessary to determine the mounting orientation of the camera.
• • Adjusting the calibration board height to the height of the camera is possible without any additional measuring tools.
• • The lateral positioning of the panel can be done via body features.
• • The calibration board can align itself in embodiments of the invention by itself horizontally and vertically, whereby a misalignment can be almost excluded!

10

contraption for placing a calibration board

12

calibration board

13

vehicle

14

Vehicle camera system

15

vehicle longitudinal axis

16

holder

18

laser pointer

20

divalent camp

21

pivot bearing

22

stand

24

locking device

26

laser beam

Claims (9)

Contraption ( 10 ) for placing a calibration board ( 12 ) in front of a vehicle camera system ( 14 ) with - a holding device ( 16 ) for the calibration board, wherein the holding device is designed such that it allows a vertical and horizontal adjustment and fixation of the calibration board, and - a target device ( 18 ) provided for aligning the calibration panel with respect to the vehicle camera system. Apparatus according to claim 1, characterized in that further comprises a first spirit level for horizontal adjustment of the calibration panel and a second spirit level are provided for vertical adjustment of the calibration board. Device according to claim 1, characterized in that the holding device ( 16 ) a bivalent bearing ( 20 ) with two degrees of freedom for holding the calibration chart ( 12 ), so that the calibration panel can adjust itself horizontally and vertically due to gravity. Device according to one of claims 1 to 3, characterized in that the target device ( 18 ) comprises a laser pointer which, according to the adjustment of the calibration table ( 12 ) and which is arranged such that a laser beam emitted by it ( 26 ) in the direction of the vehicle camera system ( 14 ) runs. Device according to a the claims 1 to 3, characterized in that the aiming device is a leveling device includes, which allows an adjustment of the calibration board. Device according to one of the preceding claims, characterized in that the holding device ( 16 ) a stand ( 22 ) on which the calibration board ( 12 ) by means of a locking device ( 24 ) can be fixed. Device according to claim 6, characterized in that the locking device ( 24 ) is designed such that the calibration board ( 12 ) rotatable for horizontal adjustment on the stand ( 22 ) can be stored. Device according to one of the preceding claims characterized in that the locking device further formed in such a way is that the calibration panel rotatable for vertical adjustment on stand can be stored. Method for arranging a calibration table ( 12 ) with a device ( 10 ) according to one of the preceding claims in front of a vehicle camera system ( 14 ) with the following steps: - positioning the device ( 10 ) according to one of the preceding claims in front of the vehicle camera system ( 14 ), - centering the device ( 10 ) in front of the vehicle camera system ( 14 ), - horizontal and vertical adjustment of the calibration table ( 12 ) by means of the holding device ( 16 ) for roughly aligning the calibration board ( 12 ) with respect to the vehicle camera system ( 14 ), and - vertical and horizontal alignment of the calibration table ( 12 ) by means of the aiming device ( 18 ) such that the calibration table ( 12 ) exactly at the height of the vehicle camera system ( 14 ) and is centrally located to this.