DE102012024879A1 - Driver assistance system for at least partially decelerating a motor vehicle, motor vehicle and corresponding method - Google Patents

Abstract

The invention relates to a driver assistance system (2) for at least partially braking a motor vehicle (1), having a detection device (6) for detecting an obstacle (11) in an environmental region (9) in the direction of travel (8) in front of the motor vehicle (1) and Detecting a distance (10) to the obstacle (11), and with a control device (3) which is designed depending on the detected distance (10) control signals (5) to a brake system (4) of the motor vehicle (1) and by means of the control signals (5) to cause the at least partial braking of the motor vehicle (1), wherein the driver assistance system (2) comprises a detection device (12, 13) for providing sensor data with respect to the surrounding area (9) and checking means (14) designed to check, based on the sensor data, whether the obstacle (11) is a predefined object (18) and, if the obstacle (11) is the predefined object (18), the delivery of the S to prevent expensive signals (5) to the brake system (4).

Description

The invention relates to a driver assistance system for at least partially braking a motor vehicle, having a detection device for detecting an obstacle in a surrounding area in the direction of travel in front of the motor vehicle and for detecting a distance to the obstacle, d. H. a distance in the direction of travel between the obstacle and the motor vehicle. The driver assistance system also comprises an electronic control device which, depending on the detected distance, can deliver control signals to a brake system of the motor vehicle and thereby cause the at least partial deceleration. The invention also relates to a motor vehicle having such a system and to a corresponding method.

Driver assistance systems for the automatic braking of a motor vehicle are already state of the art. In such systems, by means of a detection device - usually an infrared sensor (IR) - the distance to an obstacle, typically to another vehicle, detected, which is located in front of the motor vehicle. Depending on the measured distance, it is then possible, for example, to calculate the time to collision (TTC) and, depending on the TTC, an automatic braking process of the motor vehicle can optionally be initiated. If the TTC falls below a predetermined threshold, braking is initiated. On the other hand, a distinction is made between fully automatic systems on the one hand and semi-autonomous systems on the other. In fully autonomous systems, the braking operation is completely controlled by the driver assistance system without the driver having to intervene. In contrast, in semi-autonomous systems, the motor vehicle is only partially decelerated by the control device, and it is additionally issued an optical and / or haptic and / or audible warning to the driver. The driver can then complete the braking process himself and completely decelerate the motor vehicle by means of the brake pedal or allow the driver assistance system to reduce the impact energy when hitting the obstacle. The present invention can be applied to both types of systems.

By such driver assistance systems in particular rear-end collisions from behind and thus collisions with a vehicle in front can be prevented. An infrared braking system for automatic braking of a motor vehicle is already for example from the document DE 40 11 403 A1 known. The design of an infrared sensor for the detection of vehicles in front is in turn from the document EP 0 380 797 B1 known.

The known from the prior art driver assistance systems for the automatic braking of a motor vehicle also have disadvantages: It has namely been found that the automatic braking is initiated in some cases by the driver assistance system without a collision with an obstacle threatens.

It is an object of the invention to improve the reliability of a driver assistance system of the type mentioned in comparison with the prior art.

This object is achieved by a driver assistance system, by a motor vehicle and by a method having the features according to the respective independent claims. Advantageous embodiments of the invention are the subject of the dependent claims, the description and the figures.

An inventive driver assistance system is designed for at least partial braking of a motor vehicle. The driver assistance system may be a semi-autonomous or fully autonomous system. The driver assistance system comprises a detection device for detecting an obstacle in a surrounding area in the direction of travel in front of the motor vehicle. The detection device detects a distance to the obstacle. The driver assistance system also has an electronic control device that can deliver control signals to a brake system of the motor vehicle depending on the detected distance. By means of the control signals, the at least partial deceleration of the motor vehicle is caused. According to the invention, the driver assistance system has a detection device for providing sensor data relating to the surrounding area and checking means which check, based on the sensor data, whether the obstacle is a predefined object and, if the obstacle is the predefined object, prevent the delivery of the control signals to the brake system ,

The invention is based on several findings: It is based initially on the knowledge that the known from the prior art automatic or semi-autonomous braking systems in some situations do not work properly and, for example, initiate the automatic braking, although no threat of collision with an obstacle. The invention is based on the recognition that such situations occur, for example, at toll booths or other entrance and exit areas where the motor vehicle is a barrier or other barrier must happen. Because the detection device is typically designed as an infrared sensor and placed behind the windshield, such a barrier is usually interpreted as an obstacle and slows down the motor vehicle. The invention is further based on the finding that these disadvantages of the prior art can be circumvented by providing checking means which make the braking process plausible depending on sensor data of a detection device and in this case check whether the detected obstacle is a predetermined object (for example a barrier). is or not. If it is detected that the obstacle is the predetermined object, the automatic braking operation can be prevented. Such an approach improves the reliability of the driver assistance system as compared to the prior art and avoids unnecessary braking.

In an embodiment, it is provided that the predefined object is a barrier. Thus, the checking means checks whether the detected obstacle in front of the motor vehicle is a barrier or not. If such a barrier is identified in the sensor data of the detection device, the automatic braking is prevented. This embodiment proves to be particularly advantageous - for example on toll stations - in which the motor vehicle typically has to pass through a toll gate. Such toll stations are typically located on highways. A barrier may also be present, for example, when entering a garage or when leaving a garage.

However, the invention is not limited to the identification of a barrier as an object and can be applied to other objects such as a gate or the like. Generally speaking, the term "predetermined object" is preferably understood to mean a barrier or a barrier, which is movable between a blocking position and a release position.

Preferably, the detection device is an infrared sensor. Such sensors for the detection of obstacles have already proven themselves. With an infrared sensor, the distance to the obstacle and thus the TTC can be measured very quickly, so that the reaction time of the driver assistance system is very low. The infrared sensor may, for example, be placed behind the windscreen of the motor vehicle.

It proves to be advantageous if the detection device for providing the sensor data is a separate sensor device from the detection device. Namely, it can be detected with respect to a plausibility check whether the obstacle is the predetermined object or not with a sensor device different from the detection device.

Particularly preferably, the detection device comprises a camera which provides images of the surrounding area as sensor data. The verification means can then identify the predefined object in the images. By way of example, with the aid of images from a camera, it is possible to find characteristic points or features in the images, and optical flow vectors can be calculated into the characteristic features which enable tracking of the pixels over a sequence of images. Optionally, it is also possible to perform a pattern recognition with regard to the predefined object and thus to reliably identify a specific geometric shape. Such pattern recognition is already used for the detection of vehicles or pedestrians. The predetermined object can thus be detected particularly reliably and quickly in the images. By means of a camera, the object can thus be clearly detected, so that errors in the review can be prevented.

The camera may be, for example, a video camera. It can be a CCD camera or a CMOS camera.

As a camera, a front camera is preferably used, which can be placed behind the windshield and detects the surrounding area in front of the vehicle. Such cameras are already prior art and are usually used to automatically control the headlights of the motor vehicle and / or to detect pedestrians or other obstacles that are in front of the motor vehicle.

The checking means can use the images to determine the current position of the object relative to the motor vehicle and determine whether the object is the obstacle or not, depending on the current relative position of the object and on the distance measured by the detection device to the obstacle. With the help of images from a camera, it is possible with high accuracy to determine in which position the identified object is in relation to the motor vehicle. The object can even be tracked in the images of the camera, so that the respective current position of the object can be correlated with the measured distance to the obstacle.

To identify the object in the images, characteristic features such as edges and / or corners can first be detected in the images. As a characteristic Features, for example, the so-called Harris points can be detected ( C. Harris and M. Stephens "A combined corner and edge detector" in Proceedings of the 4th Alvey Vision Conference, pages 147-151, 1988 ). For the characteristic features, optical flow vectors can then be calculated according to the Lucas-Kanade method, and a tracking algorithm can be carried out ( Bruce D. Lucas and Takeo Kanade "An Iterative Image Registration Technique with an Application to Stereo Vision" pages 674-679, 1981 ). In addition, the movement of the motor vehicle can also be determined, wherein, for example, operating parameters such as the current speed and / or the current yaw rate and / or the current pitch angle of the motor vehicle can be determined. These operating parameters can be tapped, for example, on the CAN bus. This vehicle movement can then be transformed into the coordinate system of the camera taking into account calibration data of the camera. Depending on the optical flow vectors as well as on the vehicle movement, the current three-dimensional position of the characteristic points can then be determined ( HC Longuet Higgins and K. Prazdny "The Interpretation of a Moving Retinal Image" RoyalP, B-208: 385_397, 1980 ). This method proves to be particularly advantageous for static objects, such as a barrier. It works very reliably with characteristic points that belong to a static and thus stationary object. Moving characteristic points can be filtered out. In this way it is ensured that the automatic braking is prevented only in the predetermined object and in other obstacles, the motor vehicle is reliably braked.

A method for detecting crash barriers based on images of a camera is already state of the art and, for example, in the document US 2012/0069185 A1 described.

Additionally or alternatively, the detection device may comprise at least one distance sensor, in particular at least one ultrasonic sensor and / or at least one radar sensor and / or at least one lidar sensor (for example a laser scanner) for providing the sensor data. It is also possible, with the aid of distance values of a distance sensor, to determine with sufficient accuracy whether the detected obstacle is the predetermined object, for example a barrier or the like. Namely, said distance sensors are typically arranged on the front bumper of the motor vehicle, so that in the absence of measured values or in the absence of detection, it can be concluded with high probability that the obstacle is a barrier which is arranged at a certain height above the ground , If the motor vehicle is moving towards a barrier, this barrier is detected exclusively by the detection device, while the at least one distance sensor can not detect the barrier and thus does not deliver distance values. By means of this plausibility check can thus be reliably deduced the presence of a barrier in front of the motor vehicle.

In one embodiment, it is provided that the checking means then interpret the obstacle as the predefined object, in particular as a barrier, and then prevent the delivery of the control signals to the brake system if, after detection of the obstacle by the detection device, the at least one distance sensor does not detect an object and thus delivers no measured values. This embodiment can also be combined with the object recognition by means of the camera, in order to make it plausible once again whether the obstacle is actually the predefined object or not. The advantage of a distance sensor is that already existing distance sensors can be used, such as the already existing usually ultrasonic sensors of a parking aid.

The invention also relates to a motor vehicle having a driver assistance system according to the invention.

An inventive method is used to operate a driver assistance system for at least partially braking a motor vehicle, wherein by means of a detection device, an obstacle in a surrounding area in the direction of travel is detected in front of the vehicle and a distance to the obstacle is detected. By means of a control device, depending on the detected distance, control signals are emitted to a brake system of the motor vehicle, and by means of the control signals the at least partial braking of the motor vehicle is caused. Sensor data relating to the environmental area is provided by means of a detection device, wherein checking means check on the basis of the sensor data whether the obstacle is a predefined object and, if the obstacle is the predefined object, prevent the delivery of the control signals to the brake system.

The preferred embodiments presented with reference to the driver assistance system according to the invention and their advantages apply correspondingly to the motor vehicle according to the invention and to the method according to the invention.

Further features of the invention will become apparent from the claims, the figures and the Figures. All the features and feature combinations mentioned above in the description as well as the features and feature combinations mentioned below in the description of the figures and / or shown alone in the figures can be used not only in the respectively indicated combination but also in other combinations or alone.

The invention will now be described with reference to a preferred embodiment and with reference to the accompanying drawings.

Show it:

1 a schematic representation of a motor vehicle with a driver assistance system according to an embodiment of the invention;

2 a schematic diagram of a block diagram of the driver assistance system;

3 an exemplary picture of a camera; and

4 a flowchart of a method according to an embodiment of the invention.

An in 1 illustrated motor vehicle 1 is for example a passenger car. The car 1 includes a driver assistance system 2 , which is an automatic or semi-autonomous brake assist system. The driver assistance system 2 serves for at least partial braking of the motor vehicle 1 , A control device 3 is doing with a braking system 4 of the motor vehicle 1 electrically coupled. The control device 3 can connect to the brake system 4 control signals 5 give, by means of which the automatic braking of the motor vehicle 1 is initiated. Due to the control signals 5 can the braking system 4 namely the motor vehicle 1 at least partially decelerate.

To the driver assistance system 2 also includes a detection device, which in the embodiment as an infrared sensor 6 is trained. The infrared sensor 6 is behind a windshield 7 places and captures a surrounding area 9 in the direction of travel 8th or in the vehicle longitudinal direction in front of the motor vehicle 1 , The infrared sensor 6 can a distance 10 to an obstacle 11 measure that is in the surrounding area 9 in front of the motor vehicle 1 located. The obstacle 11 may be, for example, a vehicle in front. The current distance 10 transmitted by the infrared sensor 6 to the controller 3 which depends on the distance 10 and the relative speed between the obstacle 11 and the vehicle 1 the time to collision TTC determines and, depending on the TTC, the control signals 5 generated. If the TTC falls below a predetermined threshold, for example, the automatic braking is initiated.

In addition to the infrared sensor 6 includes the driver assistance system 2 also a detection device, which sensor data with respect to the surrounding area 9 provides. The detection device includes a camera 12 and / or distance sensors 13 , In the exemplary embodiment is preferably at least the camera 12 used while the distance sensors 13 can only be used optionally.

The camera 12 is a front camera, which is behind the windshield 7 is placed and images of the surrounding area 9 provides. These pictures are sent to checking means 14 which optionally also the distance values of the distance sensors 13 receive. The verification means 14 and the controller 3 optionally in a common component, in particular a common microprocessor 15 be integrated.

The distance sensors 13 For example, they may include ultrasonic sensors and / or lidar sensors and / or radar sensors.

An exemplary block diagram of the driver assistance system 2 is in 2 shown. The infrared sensor 6 (IR) transmits its information, namely the measured distance 10 to the obstacle 11 , both to the verification means 14 as well as to the controller 3 , The verification means 14 also receive the pictures of the camera 12 (K) and the distance values of the distance sensors 13 , The verification means 14 Check if the detected obstacle 11 is a predefined object or not. Will be recognized that the obstacle 11 the given object becomes preventive signals 16 to the controller 3 delivered, which is the delivery of the control signals 5 to the brake system 4 (B) prevent.

The predefined object is for example a barrier 18 as shown in the exemplary camera image 17 according to 3 is shown. This barrier 18 is using the verification means 14 in the pictures of the camera 12 detected, and it checks if the obstacle 11 the closets 18 is or not. If so, the prohibition signals become 16 issued.

For detection of the barrier 18 can take pictures of the camera 12 pattern recognition with respect to characteristic features. Optical characteristic vectors can then be calculated for the characteristic features, and the flow vectors can be combined in a manner known per se to form a common object become. The flow vectors of a common object can then be traced in the sequence of images, so that the current position of the barrier 18 with respect to the motor vehicle 1 is known. To determine the current position of the barrier 18 can also operate parameters of the motor vehicle 1 are used, in particular the current speed and / or the yaw rate and / or the pitch angle. Also calibration data of the camera 12 can be used.

Will the barrier 18 Detected in the images, it is checked in the next step, whether the barrier 18 actually the obstacle 11 is. For this purpose, the current position of the barrier 18 with the distance 10 to the obstacle 11 compared. Only when it is determined that the obstacle 11 the closets 18 is, the prevention signals become 16 generated.

For plausibility of this decision, the distance values of the distance sensors 13 be used. Here, the verification means 14 Check if the distance sensors 13 have detected an object or not. At a barrier 18 which are located outside the detection areas of the distance sensors arranged on the bumper 13 No readings are taken by the distance sensors 13 delivered. This is a clear indication that the obstacle 11 a barrier 18 is.

A flow chart of a method according to an embodiment of the invention is shown in FIG 4 shown. The method starts in a first step S1. In a second step S2, the infrared sensor detects 6 the obstacle 11 , In a subsequent step S3 then the current distance 10 to the obstacle 11 certainly. In a further step S4 is from the distance 10 and from a relative speed between the obstacle 11 and the vehicle 1 the TTC is calculated. In parallel, in a step S5 pictures 17 by means of the camera 12 detected. In a subsequent step S6 is in the pictures 17 the predetermined object 18 identified. In a further step S7, the current position of the object 18 determined and the object 18 is being tracked. In a step S8 it is then checked whether the object 18 and the obstacle 11 one and the same object or not. Is the object 18 the obstacle 11 , in a step S9, the prohibition signals 16 to the controller 3 issued. Will not be prevention signals 16 delivered, in a step S10, the delivery of the control signals 5 to the brake system 4 and thus a deceleration of the motor vehicle 1 when the TTC is less than a predetermined threshold.

Optionally, it can also be checked in step S8 whether the distance sensors 13 have detected an object or not. The prevention signals 16 can only be dispensed if the distance sensors 13 have detected no object and it is at the obstacle 11 thus a barrier located above the ground 18 is.

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 4011403 A1 [0003]
• EP 0380797 B1 [0003]
• US 2012/0069185 A1 [0018]

Cited non-patent literature

• C. Harris and M. Stephens "A combined corner and edge detector" in Proceedings of the 4th Alvey Vision Conference, pages 147-151, 1988. [0017]
• Bruce D. Lucas and Takeo Kanade "An Iterative Image Registration Technique with an Application to Stereo Vision" pages 674-679, 1981 [0017]
• HC Longuet Higgins and K. Prazdny "The Interpretation of a Moving Retinal Image" Royal P, B-208: 385_397, 1980 [0017]

Claims (10)

Driver assistance system ( 2 ) for at least partially decelerating a motor vehicle ( 1 ), with a detection device ( 6 ) for detecting an obstacle ( 11 ) in a surrounding area ( 9 ) in the direction of travel ( 8th ) in front of the motor vehicle ( 1 ) and for detecting a distance ( 10 ) to the obstacle ( 11 ), and with a control device ( 3 ), which is designed, depending on the detected distance ( 10 ) Control signals ( 5 ) to a braking system ( 4 ) of the motor vehicle ( 1 ) and by means of the control signals ( 5 ) the at least partial deceleration of the motor vehicle ( 1 ), characterized in that the driver assistance system ( 2 ) a detection device ( 12 . 13 ) for providing sensor data relating to the surrounding area ( 9 ) and verification means ( 14 ), which are designed to check, based on the sensor data, whether the obstacle ( 11 ) a predefined object ( 18 ) and, if the obstacle ( 11 ) the predefined object ( 18 ), the delivery of the control signals ( 5 ) to the brake system ( 4 ) to prevent. Driver assistance system ( 2 ) according to claim 1, characterized in that the predefined object ( 18 ) is a barrier. Driver assistance system ( 2 ) according to claim 1 or 2, characterized in that the detection device ( 6 ) is an infrared sensor. Driver assistance system ( 2 ) according to one of the preceding claims, characterized in that the detection device ( 12 . 13 ) one of the detection device ( 6 ) is separate sensor device for providing the sensor data. Driver assistance system ( 2 ) according to one of the preceding claims, characterized in that the detection device ( 12 . 13 ) a camera ( 12 ) for providing images of the surrounding area ( 9 ) as sensor data and the checking means ( 14 ) are adapted to the predefined object ( 18 ) in the pictures. Driver assistance system ( 2 ) according to claim 5, characterized in that the checking means ( 14 ) are adapted, based on the images, the current position of the object ( 18 ) and depending on the current position of the object ( 18 ) and depending on the distance ( 10 ) to the obstacle ( 11 ) determine whether the object ( 18 ) the obstacle ( 11 ). Driver assistance system ( 2 ) according to one of the preceding claims, characterized in that the detection device ( 12 . 13 ) at least one distance sensor ( 13 ), in particular at least one ultrasonic sensor and / or at least one radar sensor and / or at least one lidar sensor, for providing the sensor data. Driver assistance system ( 2 ) according to claim 7, characterized in that the checking means ( 14 ) are designed to remove the obstacle ( 11 ) then as the predefined object ( 18 ) and the delivery of the control signals ( 5 ) to the brake system ( 4 ) when, after detection of the obstacle ( 11 ) by the detection device ( 6 ) the at least one distance sensor ( 13 ) no object ( 18 ) detected. Motor vehicle ( 1 ) with a driver assistance system ( 2 ) according to any one of the preceding claims. Method for operating a driver assistance system ( 2 ) for at least partially decelerating a motor vehicle ( 1 ), wherein by means of a detection device ( 6 ) an obstacle ( 11 ) in a surrounding area ( 9 ) in the direction of travel ( 8th ) in front of the motor vehicle ( 1 ) is detected and a distance ( 10 ) to the obstacle ( 11 ), and wherein by means of a control device ( 3 ) depending on the detected distance ( 10 ) Control signals ( 5 ) to a braking system ( 4 ) of the motor vehicle ( 1 ) and by means of the control signals ( 5 ) the at least partial deceleration of the motor vehicle ( 1 ), characterized in that by means of a detection device ( 12 . 13 ) Sensor data relating to the environmental area ( 9 ) and that checking means ( 14 ) check the sensor data according to the obstacle ( 11 ) a predefined object ( 18 ) and, if the obstacle ( 11 ) the predefined object ( 18 ), the delivery of the control signals ( 5 ) to the brake system ( 4 ) prevent.

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