DE102015008887A1 - Method and device for calibrating a head-up display in a vehicle - Google Patents

Abstract

The invention relates to a method for calibrating a head-up display in a vehicle, in which a virtual image output by the head-up display (3) is compared with a possible eye position of a driver. In a method in which a low-cost calibration operation is performed, a measuring unit (11) provided with a marking (15) is positioned at a possible head position of the driver and a measuring target (7) located in front of the vehicle (5) is detected, wherein a Image recording device (17) for determining the possible eye position of the driver simultaneously receives the mark (15) of the measuring unit (11), wherein from a determined offset of the measuring unit (11) and the image pickup unit (17) an electronic correction for calibration of the virtual image of the head-up -Displays (3) is determined.

Description

The invention relates to a method for calibrating a head-up display in a vehicle, in which a virtual image output by the head-up display is matched with a possible eye position of a driver, and a device for carrying out the method.

In vehicles, head-up displays are often used in which augmented reality is used for display. Under this augmented reality, a computer-aided extension of the perception of reality is to be understood hereinafter by generating a visual representation in the display area of the head-up display by means of additional information generated by means of overlaying and overlaying.

Due to tolerances in the installation of the head-up display in the vehicle, the position of the virtual image mostly deviates from the expected target position, as in 4 is shown. The solid frame in the left image corresponds to the expected target position of the virtual image. The dashed frame corresponds to the actual image position due to the installation tolerances of the head-up display. This shift between the nominal position and the actual position of the image of the head-up display leads to incorrect augmentations, as illustrated in the right image. Therefore, the offset of the virtual image must be corrected. This can either be done via adjusting screws in production when installing the head-up display in the vehicle or it can be performed purely electronic by the content displayed in the virtual image of the head-up display are moved when driving the head-up display.

Another key feature of the head-up display is that drivers of different sizes see the virtual image of the head-up display at a different angle. That is, drivers of different sizes see the virtual image of the head-up display in different positions against the background of reality. If the eyes are higher up, the virtual image of the head-up display is perceived against the backdrop of reality, and if the eyes are further down, the virtual image of the head-up display is perceived against the background of reality above. This leads to errors in the contact-analogous drawing of virtual objects, which are referred to as parallax errors.

From the DE 10 2010 013 532 A1 An arrangement is known in which the street view on the head-up display display is corrected. For this purpose, information inputs are determined by means of driver assistance systems and, based on these information inputs, display requests for the head-up display are derived. The headup display includes a graphics engine that translates the display requirements into graphical representations describing the information by means of display software or programming. The graphics engine includes programming to compensate for the curved and sloping surface of the windscreen and any other surfaces to which the graphic is to be projected. In addition, an occupant eye location detection system is known to determine the head of the vehicle occupant, or further, the orientation or gaze location of the occupant's eyes. The estimation of the eye location and a registration of images of the head-up display thus allow a representation of the virtual images from the perspective of the operator with a correct image. However, this method is based on a high computational effort.

The object of the invention is to provide a method and a device for calibrating a head-up display in a vehicle, which provides a correct virtual image for drivers of different sizes and yet is easy to perform.

The invention results from the features of the independent claims. Advantageous developments and refinements are the subject of the dependent claims. Other features, applications and advantages of the invention will become apparent from the following description, as well as the explanation of embodiments of the invention, which are illustrated in the figures.

The invention is achieved with a method in which a measuring unit provided with a marking is positioned at a possible head position of the driver and detects a measuring target located in front of the vehicle, wherein an image recording device for detecting the possible eye position of the driver simultaneously receives the marking of the measuring unit , wherein an electronic correction for calibration of the virtual image of the head-up display is determined from a mediated offset of the measuring unit and the image recording unit. This has the advantage that the electronic correction of the mechanical offset of the head-up display as well as the correction of the parallax error is performed in a single calibration step. This simplifies the calibration effort, which reduces the costs for the calibration process. It can be dispensed with the vote of the image capture device on the absolute coordinate system of the vehicle. The measuring unit and the image recording device form a relative coordinate system with each other, which enables a particularly efficient calibration procedure.

Advantageously, the measuring unit moves during a calibration process a plurality of possible eye positions in a predetermined area of the vehicle to determine the offset for each eye position. Thus, a correct virtual image is generated for drivers of different sizes.

In one embodiment, the offset determined for each possible eye position is stored together with the eye position. As a result, these data can be used later during the drive of the vehicle in order to use these data to determine the actual offset for the eye position predetermined by the real driver and to correct the virtual image of the head-up display accordingly.

In one embodiment, the predetermined area comprises a region of the vehicle from which a virtual image of the head-up display is visible. Thus, in the calibration process, a plurality of eye positions are detected and adjusted in order to know the possible eye position of the driver of the vehicle during a driving operation and to be able to correct the virtual image of the head-up display.

In one variant, the calibration process of the head-up display is performed at the end of the tape production of the vehicle. At this time, the positions of the head-up display and the image capture device installed in the vehicle are known, so that only the possible eye positions with respect to the measurement target need to be determined.

In a further embodiment, an actual offset of the head-up display for a current eye position of the driver from the stored measured values of determined during the calibration process offset and associated eye position, preferably linear, interpolated. In this case, even when the driver's eyes are at a position that was not taken into account during the calibration process, an offset for the electronic correction is nevertheless determined exactly, since the closest measured values are used for the interpolation.

• – ein Headup-Display zur Ausgabe eines virtuellen Bildes,
• – eine Messeinheit, welche in Höhe einer möglichen Kopfposition des Fahrers positioniert ist,
• – ein Messmuster, das vor dem Fahrzeug angeordnet ist und von der Messeinheit detektierbar ist,
• – eine, an der Messeinheit befindliche Markierung,
• – eine, im Fahrzeuginnenraum fixierte Bildaufnahmeeinrichtung zur Detektion der Markierung der Messeinheit sowie ein, mit der Messeinheit und der Bildaufnahmeeinrichtung verbundenes Kalibriersystem zur Bestimmung eines, von der Messeinheit und der Bildaufnahmeeinrichtung ermittelten Versatzes und zur Ausgabe eines aus dem Versatz bestimmten Korrektursignales an das Headup-Display.

A development of the invention relates to a device for calibrating a head-up display of a vehicle, comprising

• A headup display for displaying a virtual image,
• A measuring unit which is positioned at the height of a possible head position of the driver,
• A measurement pattern, which is arranged in front of the vehicle and can be detected by the measuring unit,
• A marking located on the measuring unit,
• - One, fixed in the vehicle interior image pickup device for detecting the marking of the measuring unit and a connected to the measuring unit and the image pickup calibration system for determining a, determined by the measuring unit and the image pickup device offset and outputting a determined from the offset correction signal to the head-up display ,

This embodiment has the advantage that a mechanical offset, which is caused by the installation of the head-up display and a parallax error, which occurs through different positions of the eyes of the driver when viewing the virtual image of the head-up display, simultaneously in one Process step can be calibrated, whereby a particularly efficient calibration process is possible.

Advantageously, the image recording device is arranged near a windshield and directed to the measuring unit. In this arrangement, the image recording device is not only realized a reliable orientation of this on the measuring unit, but at the same time realizes a space-saving arrangement.

In one embodiment, the measurement target is a geometric pattern, which can preferably be resolved well by the measurement unit. This measurement target simulates the vehicle environment during the calibration process.

In a variant, a further front-facing camera is arranged in the vehicle for observing a driving event and / or a detection of the measurement target. By means of this additional camera, objects of the real environment can be detected, which are to be marked by the head-up display contact-analog in its display area. The acquisition of the measurement target by the additional second camera allows the evaluation together with the results of the measuring unit a completely closed system in which each tolerance can be determined and then corrected.

Further advantages, features and details will become apparent from the following description in which - where appropriate, with reference to the drawings - at least one embodiment is described in detail. Described and / or illustrated features may form the subject of the invention itself or in any meaningful combination, optionally also independent of the claims, and may in particular additionally be the subject of one or more separate application / s. Same, similar and / or functionally identical parts are provided with the same reference numerals.

Show it:

1 an embodiment of the device according to the invention,

2 an embodiment of a scanning of the measuring unit according to 1 .

3 an example of a calibration table,

4 a virtual image of the headup display according to the prior art.

In 1 is a device 1 represented, by means of which at the end of tape process of manufacturing a vehicle, a virtual image of a head-up display 3 can be corrected.

The headup display 3 is stuck in the vehicle 5 installed, taking in front of the vehicle 5 a measurement target 7 is constructed in the form of a geometric pattern. This geometric pattern has a unique location in space, allowing the position of the measurement target 7 relative to the vehicle 5 is clearly and precisely defined. A robotic arm 9 drives with a measuring unit 11 in the vehicle 5 to a position where later a driver's head is suspected. From this position the measuring unit detects 11 through the windshield 13 both the virtual image of the headup display 3 as well as the measurement target 7 which is built behind it. At the measuring unit 11 is a mark 15 attached, which by a video camera, also called a HET camera 17 (Head Eye Tracking Camera) is recorded. This HET camera 17 is also in the area of the windscreen 13 positioned and on the mark 15 the measuring unit 11 directed. Instead of the driver's eyes, the HET camera captures 17 the mark 15 on the measuring unit 11 and thus the position of the measuring unit 11 ,

During the calibration process is by the representation of the measuring unit 11 recorded test pattern within the display area of the headup display 3 an offset between the virtual image of the headup display 3 and the measurement target 7 determined. Due to the exact alignment of the measurement target 7 relative to the vehicle 5 This determined offset can be used directly for the electronic correction of the position of the virtual image in the display area of the head-up display 3 be used. In this case, the determined offset corresponds to the necessary electronic correction of a specific eye position, specifically the eye position at which the measuring unit is located 11 currently located. This eye position is over the mark 15 from the HET camera 17 detected. The thus determined offset thus summarizes both the necessary correction by installation tolerances of the head-up display 3 in the vehicle 5 as well as the necessary correction by the parallax error, which arises from different eye positions, in a single step together.

To determine a possible correction for all possible eye positions, the measuring unit moves 11 during the calibration process a variety of possible eye positions within a given area, the so-called eye-box 19 , from. This eye box 19 is in 2 and represents an area in the vehicle 5 representing the virtual image of the headup display 3 is visible. All possible eye positions must be within the eye box 19 be present so the virtual image of the headup display 3 is completely seen.

While starting the sufficiently large number of eye positions within the Eye-Box 19 During the calibration process, the necessary offset is determined for each of these eye positions and stored together with the eye position in a calibration table. If, during normal operation of the vehicle, the driver's eye position is located elsewhere, the required electronic correction is determined by interpolation of the stored measured values located closest to each other. This interpolation can be linear. In a conceivable variant, not only the closest measuring points (offset and eye position) but also measuring points which are further away from the actual eye position are used for the interpolation.

The measured values ascertained during the calibration process can be stored, for example, in a calibration table as shown in FIG 3 is shown. The calibration table is part of a calibration system 21 to which the HET camera 17 connected. The calibration table is in a table log-up 23 stored, in which optionally also the interpolation takes place. This calibration system 21 determined in a correction module 25 Correction signals with regard to the image offset, the displacement of individual virtual elements and / or the parallax correction and gives them to the head-up display 3 out. This calibration system 21 has the advantage that the calibration table only coordinates the relative coordinate system of the HET camera 17 contains. This coordinate system of the HET camera 17 must be for the ongoing operation of the headup display 3 not calibrated to the coordinate system of the vehicle. Due to the proposed calibration procedure of the headup display 3 implicitly also a calibration of the HET camera 17 , which makes the calibration of the HET camera 17 as a separate operation deleted.

Also a rotation of the virtual image of the headup display 3 could be detected during calibration and entered in the calibration table. When interpolating the measurements from the calibration table, multiple lines can be combined to increase accuracy and average out noise.

For a suitable choice of measurement target 7 , z. As a regular grid, a distortion of the virtual image of the head-up display 3 through the measuring unit 11 be determined. This distortion is caused by the reflection of the virtual image on the windshield 13 and possibly other effects within the optical design of the head-up display 3 , If the distortion is known, then it can be compensated electronically via a suitable predistortion. The perceived distortion is typically different for each position within the eye box 19 , so that during the calibration process in the calibration table for each approached eye position, a corresponding provision for predistortion z. B. can be stored in the form of a so-called warping matrix.

In addition to the HET camera 17 can in the vehicle 5 a forward facing camera 27 be arranged. Such a camera 27 will also be behind the windshield 13 mounted and has the purpose of driving in front of the vehicle 5 to observe. This camera 27 can be used for example for the detection of other road users or for the detection of lanes. By capturing road users through this additional camera 27 can then be in the virtual image of the headup display 3 these road users are tagged contact analogue. In such a case, it is advantageous if, during the calibration process, the front-facing camera 27 also the measurement target 7 detected. Together with the evaluation of the measuring unit 11 on the robot arm 9 then a completely closed system can be made by implicitly determining and compensating for any tolerance. This includes the tolerances regarding the installation of the front-facing camera 27 , the HET camera 17 and the headup display 3 itself. In this case it is not absolutely necessary to use the measurement target 7 particularly accurate placement, resulting in a further cost advantage during the calibration process. However, driver assistance functions require precise calibration of the front-facing camera 27 concerning the vehicle 5 , which makes a relative to the vehicle 5 exact placement of the measurement target 7 may become necessary. Likewise, virtual content can be seen in the virtual image of the headup display 3 to be drawn, an exact calibration of the headup display 3 relative to the vehicle 5 which also requires an exact placement of the measurement target 7 necessary.

Although the invention has been further illustrated and explained in detail by way of preferred embodiments, the invention is not limited by the disclosed examples, and other variations can be derived therefrom by those skilled in the art without departing from the scope of the invention. It is therefore clear that a multitude of possible variations exists. It is also to be understood that exemplified embodiments are really only examples that are not to be construed in any way as limiting the scope, applicability, or configuration of the invention. Rather, the foregoing description and description of the figures enable one skilled in the art to practice the exemplary embodiments, and those of skill in the knowledge of the disclosed inventive concept may make various changes, for example as to the function or arrangement of individual elements recited in an exemplary embodiment, without Protection area defined by the claims and their legal equivalents, such as further explanations in the description.

LIST OF REFERENCE NUMBERS

1

contraption

3

Head-Up Display

5

vehicle

7

measuring target

9

robot arm

11

measuring unit

13

Windshield

15

mark

17

HET camera

19

Eye-Box

21

calibration System

23

Table log up

25

correction module

27

front-facing camera

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been 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.

Cited patent literature

• DE 102010013532 A1 [0005]

Claims (10)

Method for calibrating a head-up display in a vehicle, in which one of the head-up display ( 3 ) is compared with a possible eye position of a driver, characterized in that a, with a mark ( 15 ) provided measuring unit ( 11 ) is positioned at a possible head position of the driver and one in front of the vehicle ( 5 ) measuring target ( 7 ), wherein an image recording device ( 17 ) to determine the possible eye position of the driver at the same time the mark ( 15 ) of the measuring unit ( 11 ), wherein from a determined offset of the measuring unit ( 11 ) and the image acquisition unit ( 17 ) an electronic correction for calibrating the virtual image of the head-up display ( 3 ) is determined. Method according to claim 1, characterized in that the measuring unit ( 11 ) during a calibration process a plurality of possible eye positions in a predetermined range ( 19 ) of the vehicle ( 5 ) for determining the offset for each eye position. A method according to claim 2, characterized in that the determined for each possible eye position offset is stored together with the associated eye position. Method according to claim 2 or 3, characterized in that the predetermined range ( 19 ) a region of the vehicle ( 5 ) from which an image of the head-up display ( 3 ) is visible. Method according to at least one of the preceding claims, characterized in that the calibration process of the head-up display ( 3 ) at the end of the production of the vehicle ( 5 ) is carried out. Method according to at least one of the preceding claims, characterized in that an actual offset of the head-up display ( 3 ) is interpolated for a current eye position of the driver from the stored measured values of the offset determined during the calibration process and the associated eye position, preferably linear. Device for calibrating a head-up display of a vehicle, comprising - a head-up display ( 3 ) of the vehicle for outputting a virtual image, - a measuring unit ( 11 ), which is positioned at the height of a possible head position of the driver, - a measurement target ( 7 ) located in front of the vehicle and by the measuring unit ( 11 ) is detectable, - one, at the measuring unit ( 11 ) mark ( 15 ), - one, fixed in the vehicle interior image pickup device ( 17 ) for the detection of the label ( 15 ) of the measuring unit ( 11 ) and - on, with the measuring unit ( 11 ) and the image recording device ( 17 ) connected calibration system ( 21 ) for determining, from the measuring unit ( 11 ) and the image recording device ( 17 ) and for outputting a correction signal determined from the offset to the head-up display ( 3 ). Apparatus according to claim 7, characterized in that the image recording device ( 17 ) near a windshield ( 13 ) and on the measuring unit ( 11 ). Device according to claim 7 or 8, characterized in that the measurement target ( 7 ) represents a geometric pattern. Apparatus according to claim 7, 8 or 9, characterized in that a further, aligned in the direction of travel camera ( 27 ) in the vehicle for observing a driving event and / or a detection of the measurement target ( 7 ) is arranged.

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