DE102013202915A1 - Method for measuring parking space for parking assistance system of motor vehicle, involves determining free parking area within parking space depending on positions of two corners and detection of obstacles within two blind ranges - Google Patents

Abstract

The method involves sampling a corner of a parking space with a distance sensor (20). A blind range is determined from the distance sensor depending on the position of the corner. Another corner of the parking space is sampled with the distance sensor. Another blind range is determined from the distance sensor depending on the position of the latter corner. The two blind ranges are selectively scanned by an optical sensor (60) for detecting the obstacles. A free parking area is determined within the parking space depending on positions of the two corners and the detection of obstacles. An independent claim is included for a computer program for allowing a computer to perform method for measuring a parking space for a parking assistance system of a motor vehicle.

Description

The present invention relates to a method and a device for measuring a parking space for a parking assistance system of a motor vehicle.

State of the art

In the field of driver assistance systems for motor vehicles, ultrasonic transducers are frequently used as sensors, in particular for parking assistance systems. If a function is provided for automatic parking space recognition, an ultrasonic sensor is usually provided on each longitudinal side of the vehicle, the possible parking spaces, e.g. at the roadside (so-called longitudinal parking spaces), detects and scans. Typically, a pulse-echo method is used, which allows using the ultrasonic sensor to determine the distance to an object in the vehicle environment.

DE 10 2004 033 078 A1 describes a method for measuring a parking space for a parking system of a motor vehicle. For this purpose, in one embodiment, a vehicle is laterally equipped with two distance sensors. A front distance sensor measures the length of the parking space as it passes a parking space at a first sampling rate. The depth of the parking space is sensed by means of a rear distance sensor operating at a second sampling rate. The distance sensors used for this purpose are ultrasonic sensors.

DE 10 2004 047 479 A1 describes a method for classifying side boundaries of a parking space for a parking assistance system of a motor vehicle. A vehicle has one front and one rear distance sensor per vehicle side. When passing the vehicle at a parking space to be scanned by the distance sensors, the length and depth of the parking space. With the aid of the rear distance sensor, the determination of the side boundary of the parking space is additionally carried out. Both the front and the rear distance sensor are designed as ultrasonic sensors.

DE 10 2005 032 096 A1 describes a method for assisting the driver of a vehicle in the detection of parking spaces suitable for the vehicle. When driving past the vehicle at a parking space it is sensed in terms of their length and depth. If the parking space is suitable for the vehicle, the vehicle is automatically braked. To check the parking space, several distance sensors in the form of ultrasonic sensors or radar sensors can be used.

If only a single ultrasonic sensor per vehicle longitudinal side is used, only the nearest point of a parking space limit can be detected and its distance determined. Assuming that the front and rear limits of a longitudinal parking space (viewed in the direction of travel) are formed by parked vehicles or similar objects, the corner of this boundary is detected by the ultrasonic sensor as the nearest point of the respective boundary.

From the measurement characteristic of a typical ultrasonic sensor, it results that the detection of a corner boundary creates a blind area which the ultrasonic sensor can not see. This is caused by the fact that the echo signals, which are reflected back from the corner boundary, are very strong and superimpose all signals originating from possibly existing objects in the blind area in such a way that a reliable signal separation is not possible. In addition, it can not be discriminated whether a real object within the blind area has generated the received ultrasound signals, or whether the presence of an object is simulated by superposing signals.

It is therefore not possible to determine with certainty whether or not there are other obstacles within this blind area. To ensure that no obstacles are overlooked, the system must assume that the entire area of the blind areas contains obstructions. This can lead to parking spaces whose dimensions are actually sufficient for the vehicle not being recognized as such.

Disclosure of the invention

The object of the invention is to improve the measuring accuracy of parking assistance systems when measuring the length of a parking space when using only one distance sensor per vehicle longitudinal side. For this purpose, an ultrasound sensor is used in combination with an optical sensor provided on the vehicle, for example a bird-view camera. Compared to measurements with a single ultrasonic sensor, blind areas can thus be avoided during the measurement.

By means of the optical sensor additional information about the blind areas, so the not visible with the ultrasonic sensor areas of a parking space obtained. By merging the measurement data of both sensors (sensor data fusion), more accurate information about the dimensions of a parking space is thus obtained.

• a) Abtasten einer ersten Eckenbegrenzung der Parklücke mit dem Abstandssensor und Bestimmen eines ersten Blindbereichs des Abstandssensors abhängig von der Position der ersten Eckenbegrenzung,
• b) Abtasten einer zweiten Eckenbegrenzung der Parklücke mit dem Abstandssensor und Bestimmen eines zweiten Blindbereichs des Abstandssensors abhängig von der Position der zweiten Eckenbegrenzung,
• c) Selektive Abtastung des ersten und zweiten Blindbereichs durch den optischen Sensor und Erkennung von Hindernissen,
• d) Bestimmen des freien Parkbereichs innerhalb der Parklücke abhängig Positionen der ersten Eckenbegrenzung und der zweiten Eckenbegrenzung und der Erkennung von Hindernissen in dem ersten und zweiten Blindbereich.

An inventive method for measuring a parking space for a parking assistance system of a motor vehicle, which has a first distance sensor on a vehicle longitudinal side, comprises at least one optical sensor and a control device, comprises the following method steps:

• a) sensing a first corner boundary of the parking space with the distance sensor and determining a first blind area of the distance sensor depending on the position of the first corner boundary,
• b) scanning a second corner boundary of the parking space with the distance sensor and determining a second blind area of the distance sensor depending on the position of the second corner boundary,
• c) Selective scanning of the first and second blind areas by the optical sensor and detection of obstacles,
• d) determining the free parking area within the parking space depending on positions of the first corner boundary and the second corner boundary and the detection of obstacles in the first and second blind areas.

First, according to the invention, when driving past a longitudinal parking space, a first corner boundary of the parking space is detected, scanned, and the distance of the first corner boundary from the vehicle is determined. Corner boundary is understood to mean the nearest corner of an object that limits the parking space in its length. The result is a not visible from the ultrasonic sensor first blind area whose position and dimensions are determined by the position of the first corner boundary.

When driving on, in the second step, a second corner boundary of the parking space is detected, scanned and determines the distance to the vehicle. Analogously to step a), a second blind area, which is not visible from the ultrasonic sensor, results whose position and dimensions are determined by the position of the second corner boundary.

In order to determine whether there are further objects within the two recognized blind areas which limit the available parking area, an optical sensor is used according to the invention which selectively scans the two blind areas and recognizes any obstacles that may be present.

Depending on the measurements of the distance sensor, which is preferably designed as an ultrasonic sensor, and the optical sensor, a free parking area can now be determined which has a much greater correspondence with the free parking area actually available than a free parking area which only determines by measuring the ultrasonic sensor alone becomes.

The invention offers the advantage that optical sensors already existing on the vehicle can usually be used in order to enable improved parking space recognition. Since only small image areas (corresponding to the blind areas of the proximity sensor) must be detected and processed by means of the optical sensor, no high computing power and / or data transmission bandwidth is required.

As an optical sensor, a camera is preferably used. In this case, for example, a camera that already exists on the vehicle can be used, such as an environment camera. Particularly preferred is a bird-view camera, also referred to as all-round vision system, surround view or around-view monitor used. This is understood to mean a system of several cameras that record the surroundings of the vehicle from different perspectives. From the images, a picture of the vehicle's surroundings is calculated from a bird's-eye view and displayed to the driver by means of a suitable algorithm. In an inventive use of such a system as an optical sensor, the coordinates of the detected blind areas are transmitted to the algorithm, so that the blind areas can be selectively scanned and obstacles within the blind areas can be detected or excluded.

Preferably, the first blind area and the second blind area are each characterized by a bounding box and the coordinates of the bounding boxes are transferred to the optical sensor. In this context, a bounding box is understood to be a substantially rectangular region whose boundaries are defined as a function of the detected first or second corner boundary. The detected corner boundary may be part of the boundary of the bounding box. Usually, however, the boundary of the bounding box is chosen with a certain safety distance from the corner boundary, so that the detected corner boundary comes to lie within the associated bounding box.

Furthermore, the boundaries of the bounding boxes are preferably determined by the distance of the detected corner boundary from the vehicle and / or from the current speed of the vehicle and / or from the known emission characteristic of the distance sensor, which is preferably designed as an ultrasonic sensor.

The coordinates of the bounding boxes are preferably determined depending on the speed of the vehicle and / or the steering angle and / or the arrangement of the optical sensor on the vehicle and / or the arrangement of the ultrasonic sensor on the vehicle. The coordinates are transferred to the optical sensor, so that a selective sampling of the bounding boxes can take place.

Preferably, detection of obstacles in step c) uses methods of digital image processing. In particular, by edge detection objects within the blind areas are recognized and classified as obstacles. If, for example, no object is detected within one or both blind areas, this result is taken into account in the calculation as to whether an adequate free space is available for a parking maneuver and is taken into account in the calculation of an optimal parking trajectory.

The evaluation of the sensor data of the optical sensor and the obstacle detection within the blind areas can be done directly in the control unit of the optical sensor, which is designed for example as a microcontroller. Alternatively, the calculations can be made in the control unit of the parking assistance system or in a mobile device, such as a smartphone or a tablet PC, which can also be used to display the vehicle environment.

According to the invention, a computer program is also proposed according to which one of the methods described herein is performed when the computer program is executed on a programmable computing device. The computer program can be, for example, a module for implementing a parking assistance system in a vehicle or an application that can be executed on a mobile device. The computer program may be stored on a machine-readable storage medium, such as on a permanent or rewritable storage medium or in association with a computer device or on a removable CD-ROM, DVD or USB stick. Additionally or alternatively, the computer program may be provided for download on a computing device, such as a server, e.g. via a data network such as the Internet or a communication connection such as a telephone connection or a wireless connection.

According to the invention, a parking assistance system is also provided with the features of the further independent claim, which is particularly suitable for carrying out one of the methods described above.

Brief description of the drawings

1 shows a process of measuring a parking space according to the prior art.

2 shows a process of measuring a parking space according to an embodiment of the invention.

3 shows a bird's eye view of a scanned parking space according to an embodiment of the invention.

In 1 the process of scanning a parking space according to the prior art is shown. As in 1a) shown is the vehicle 14 looking for a suitable parking space 30 , The vehicle 14 has a parking assistance system with an ultrasonic sensor 20 on the long side of the vehicle 14 on, which scans the area to the left of the vehicle. In this area there are two standing vehicles 40 . 50 that have a parking space 30 to confine between themselves. While the vehicle 14 the first stationary vehicle 40 is approached by the ultrasonic sensor 20 the front right corner of the stationary vehicle 40 as the first corner boundary 42 the parking space 30 recognized. Because the echo signal of the first corner boundary 42 so strong is that there are echo signals from possible other obstacles around the first corner boundary 42 so superimposed that a reliable signal separation is not possible results in a first blind area 45 of the ultrasonic sensor 20 ,

It is by means of the ultrasonic sensor 20 alone is not possible to determine if within this blind area 45 another obstacle is located. To make sure that no obstacles are overlooked, the system must assume that the entire area of the blind area 45 Contains obstacles and is not available for a parking process.

As in the 1b) and 1c) is shown, the vehicle moves 14 continue in direction F.

In 1d) is shown the situation in which the ultrasonic sensor 20 the rear right corner of the stationary vehicle 50 as a second corner boundary 52 the parking space 30 recognizes. Also in this situation results in a blind area 55 by the ultrasonic sensor 20 is not visible. To ensure that no obstacles are overlooked, the system must also assume here that the entire area of the blind area 55 Contains obstacles and is not available for a parking process.

Accordingly, the scan results in a length d of the parking space that passes through the blind areas 45 and 55 is determined. In the illustrated example, the measured length d is not large enough for a parking operation of the vehicle 14 so that the parking assistance system the parking space 30 either does not classify as a valid parking space or a non-optimal parking trajectory into the parking space 30 calculated.

In the 2 and 3 the process of scanning a parking space is shown according to the invention

The vehicle 14 indicates in addition to an ultrasonic sensor 20 on the vehicle longitudinal side still an optical sensor 60 on, which can be configured for example as a bird-view camera. Through the optical sensor, the blind areas 45 and 55 be eliminated.

In 2 is the process of detecting the corner boundaries 42 and 52 and the first and second blind areas 45 and 55 analogous to 1 shown. In the first position of the vehicle 14 ' , becomes the first corner boundary 42 detected and their position saved. A first blind area 45 is detected and through a bounding box 48 characterized. In other words, the bounding box represents 48 the first blind area 42 , The coordinates of the bounding box 48 are also saved.

If the vehicle 14 '' has reached a second position becomes the second parking vehicle 50 recognized and in an analogous manner, the coordinates of the second corner boundary 52 , as well as a second bounding box 58 that the second blind area 55 of the ultrasonic sensor 20 represents determined and stored.

If due to the dimensions of the blind areas 48 and 58 No parking seems possible, the distance d 'of the corner boundaries 42 and 52 however, suggesting that if there are no other obstacles in the blind areas, parking would be possible, so the coordinates of the two bounding boxes become 48 and 58 as well as the coordinates of the corner boundaries 42 and 52 to the optical sensor 60 passed.

The optical sensor 60 receives the coordinates and scans the bounding boxes 48 and 58 on obstacles. The exact positions of the bounding boxes 48 and 59 relative to the current position of the vehicle 14 For example, based on the speed of the vehicle 14 or a recorded speed curve during the scan, the steering angle or steering angle curve, and the position of the optical sensor 60 be determined.

in 3 is an example of the view shown as an executed as a bird-view camera optical sensor 60 supplies. The vehicle 14 at his current position, as well as the parking space 30 limiting vehicles 40 and 50 are shown in bird's eye view. Also shown are the bounding boxes 48 and 58 covering the blind areas of the ultrasonic sensor 20 represent.

The control unit of the optical sensor 60 , which may for example be designed as a microprocessor, processes the coordinates of the bounding boxes 48 and 58 and performs object recognition using digital image processing methods within the bounding boxes 48 and 58 by. Alternatively, the optical sensor sends 60 the captured images to the controller 15 the driver assistance system and the control device 15 performs obstacle detection using digital image processing methods. Since only a small portion of the entire image needs to be processed (for example, a 64x64 pixel area), high processing power and / or data transfer bandwidth is not required in either case.

Based on the result of obstacle detection within the bounding boxes 48 and 58 Now you can see the actual dimensions of the parking space 30 be determined and an optimal parking trajectory for the vehicle 14 be calculated.

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 102004033078 A1 [0003]
• DE 102004047479 A1 [0004]
• DE 102005032096 A1 [0005]

Claims (8)

Method for measuring a parking space ( 30 ) for a parking assistance system of a motor vehicle ( 14 ) with a distance sensor arranged on a vehicle longitudinal side ( 20 ), at least one optical sensor and a control device ( 15 a) sensing a first corner boundary of the parking space with the distance sensor and determining a first blind area of the proximity sensor depending on the position of the first corner boundary, b) sensing a second corner boundary of the parking space with the proximity sensor and determining a second blind area of the proximity sensor c) Selective scanning of the first and second dummy areas by the optical sensor and detection of obstacles; d) Determining the free parking area within the parking space depending on positions of the first corner boundary and the second corner boundary and the detection of obstacles in the parking space first and second blind area. A method according to claim 1, characterized in that the distance sensor is designed as an ultrasonic sensor. A method according to claim 1 or 2, characterized in that the optical sensor comprises a camera, in particular a bird-view camera. Method according to one of claims 1 to 3, characterized in that the first blind area and the second blind area is characterized in each case by a bounding box and the coordinates of the bounding boxes are transferred to the optical sensor. A method according to claim 4, characterized in that the coordinates of the bounding boxes are determined depending on the speed of the vehicle and / or the steering angle and / or the arrangement of the optical sensor on the vehicle and / or the arrangement of the ultrasonic sensor on the vehicle. Method according to one of claims 1 to 5, characterized in that the detection of obstacles in step c) by means of digital image processing methods, in particular edge detection, takes place. Computer program for carrying out a method according to one of claims 1 to 6, when the computer program is executed on a programmable computer device. Parking assistance system of a motor vehicle ( 14 ) with a distance sensor arranged on a vehicle longitudinal side, at least one optical sensor and a control device ( 15 ), wherein the distance sensor is arranged to detect a first corner boundary of a parking space and depending on the position of the first corner boundary to determine a first blind area, to detect a second corner boundary of a parking space and depending on the position of the second corner boundary to determine a second blind area, and the optical sensor is adapted to detect obstacles within the first and second blind areas by selective scanning, wherein a free parking area is performed depending on the positions of the first corner boundary and the second corner boundary and the detection of obstacles in the first and second blind areas.

Images