FIELD

The present invention relates to a device and to a method for calibrating vehicle assistance systems (VAS), in particular for detecting the position, angle and attitude of vehicles for VAS calibration.

BACKGROUND INFORMATION

Motor vehicles increasingly come equipped with driver assistance systems (DAS), for example a lane-keeping assistant, a lane-change warning, lane departure warning, a thermal imaging (night vision) camera and/or a parking assistant.

In particular in optical, i.e., camera-based driver assistance systems, it is necessary that at least one camera of the driver assistance system provides a precise image of the surroundings that conforms to reality and that is correctly aligned with the vehicle. For this purpose, all cameras of the driver assistance system must be calibrated.

In static calibration, for example of a front camera, measuring panels (“calibrating panels”), which have an optical pattern (“target pattern”), are used, for example in order to align a driver assistance system using calibrating tools (“DAS calibrating tools”) with respect to the rear axle of a vehicle. The alignment comprises in particular setting the spacing, the yaw angle, the roll angle and the pitch angle correctly. The measuring panels must be aligned left and right centrically with respect to the vehicle and at a right angle with respect to the longitudinal driving axis of the vehicle so that the DAS may be calibrated at an appropriate distance from the calibrating system.

The measuring panels must be aligned with great precision. Manual alignment of the measuring panels is therefore costly and requires much care and experience. Moreover, a measuring station is required having a leveled floor in order to avoid deviations in elevation.

Furthermore, there are vehicle-specific DAS systems, for example front camera systems, that require a dynamic calibrating drive. For this purpose, the vehicle is switched to a calibrating mode, e.g., with the aid of a diagnostic unit, and is trained by actually driving at constant speed in driving lanes on the road. The dynamic calibrating drive is very costly, time-consuming and difficult to execute in densely populated areas.

Some manufacturers prescribe a combination of static and dynamic calibrations, which is composed of the two calibrating methods.

An object of the present invention is to simplify the calibration of vehicle assistance systems.

SUMMARY

According to one exemplary embodiment of the present invention, a calibrating device for calibrating vehicle assistance systems comprises at least one target pattern; at least one sensor, which is designed to detect the position and the orientation of a vehicle to be measured with respect to the calibrating device; and a positioning device, which is designed to position the at least one target pattern on the basis of the position of the vehicle to be measured, which is detected by the at least one sensor, in such a way that the at least one target pattern is situated in a specified orientation at a specified position with respect to the vehicle to be measured.

According to one exemplary embodiment of the present invention, a method for calibrating vehicle assistance systems comprises:(a) positioning a calibrating device in front of a vehicle to be measured in accordance with one exemplary embodiment of the present invention;(b) determining the position and orientation of the vehicle with respect to the calibrating device with the aid of the at least one sensor; and(c) positioning the at least one target pattern in such a way that it is situated in a specified orientation at a specified position with respect to the vehicle.

The target pattern may be a static (target) pattern, as is required for a static calibration. The target pattern may also be a variable dynamic (target) pattern, however, in particular a tracking sequence (video sequence), which in combination with a roller test stand allows for a dynamic calibration of the VAS. Exemplary embodiments of the present invention therefore also comprise a combination of a roller test stand and a calibrating device according to an exemplary embodiment of the present invention.

The present invention makes it possible to position the at least one target pattern automatically in the correct position as a function of the current position of the vehicle to be measured. In this manner, it is possible to perform the positioning quickly, conveniently and with high precision.

In particular, no additional auxiliary devices such as lasers, for example, are required to align the target patterns correctly. This reduces the space required for the measuring station. The positioning device is also able to take into account and compensate for elevation variations. Hence, a leveled measuring station is not required.

In one exemplary embodiment, the calibrating device also comprises a moving device, which is designed to move the at least one target pattern and/or the entire calibrating device mechanically. In this manner, the at least one target pattern may be positioned automatically in a specified orientation at a desired position.

In one exemplary embodiment, the moving device comprises at least one wheel or a roller, which simplifies moving the at least one target pattern and/or the entire calibrating device mechanically.

The wheel or the roller may be guided in particular in at least one rail. The combination of a wheel or a roller and a rail makes it possible to guide the at least one target pattern and/or the entire calibrating device at low friction and with high precision to the desired position.

In one exemplary embodiment, the moving device is designed to turn the at least one target pattern about at least one axis in order to situate the at least one target pattern in accordance with the orientation of the vehicle on the measuring station exactly into the desired position and orientation on the measuring station.

In one exemplary embodiment, the calibrating device comprises at least one electronic display device, which is designed to represent the at least one target pattern optically.

The positioning device may be designed in particular to vary the display of the at least one target pattern on the at least one electronic display device in order to position the target pattern in a specified orientation at a specified position. In one exemplary embodiment, the positioning device is designed in particular to vary also the size, the orientation and/or the position of the target pattern on the at least one electronic display device as a function of the position and the alignment of the vehicle on the measuring station.

It is thus possible to display the at least one target pattern in the required size, alignment and orientation without requiring for this purpose that the at least one target pattern or the display device be moved mechanically. A calibrating device that comprises at least one such electronic display device may therefore be operated in a particularly simple, cost-effective and low-maintenance manner. Since no space is required for moving the at least one target pattern, it is possible to implement such a display device in a particularly space-saving manner.

In one exemplary embodiment, the at least one sensor comprises at least one camera that is designed to detect the vehicle to be measured optically. With the aid of a sensor, the position of the vehicle with respect to the calibrating device may be determined in particularly simple and convenient fashion. The camera may be developed in particular as a stereo camera so as to be able to determine the position and alignment of the vehicle in all three spatial directions with high precision. Multiple cameras and/or sensors may also be provided.

The at least one sensor may be situated at different positions, in particular also at the ceiling above the vehicle.

In order to improve the accuracy of the calibration and in particular to minimize inaccuracies resulting from a deviation of the longitudinal driving axis of the vehicle from the longitudinal body axis, it is possible to mount wheel adapters on the wheels of the rear axle of the vehicle, which are detected by at least one camera so as to be able to determine the alignment of the rear axle and thus of the longitudinal driving axis of the vehicle with high accuracy.

Alternatively or additionally, it is possible to determine the distance of the vehicle from the calibrating device by ultrasonic sensors and/or by mechanical sensors. The measuring results of multiple sensors may be combined with one another in order to improve the accuracy of the position determination.

In one exemplary embodiment, a method for calibrating a device for vehicle measurement comprises attaching a marking on the vehicle, which may be developed for example in the form of at least one adhesive dot so as to simplify the automatic determination of the alignment and position of the vehicle by the at least one sensor and/or to increase the accuracy.

In this instance, the method may comprise in particular attaching the marking at a location on the longitudinal driving axis of the vehicle, for example below the rear view mirror on the windshield of the vehicle.

Exemplary embodiments of the present invention are explained in greater detail below with reference to the figures.

