DE102008042640B4 - Method and device for data reduction during data transmission to a driver assistance system - Google Patents

Abstract

Method for data reduction in the transmission of the sensor data of different physical objects generated from environmental sensor signals to a driver assistance system (9), the sensor data containing measured values and confidence values assigned to the measured values, and the physical objects can be a roadway, vehicles in front or other objects or areas characterized in that the measured values belonging to a physical object, the confidence values of which exceed a predetermined threshold value, are combined into a surrounding region with a uniform confidence value before they are transmitted to the driver assistance system (9), an approximation of at least one contour of a surrounding region (1 ', 3 ', 6', 7 ') by a polygon.

Description

State of the art

The invention is based on a method for data reduction according to the preamble of claim 1.

Environmental awareness for driver assistance systems is becoming increasingly important. Sensors such as camera systems, radar and ultrasound are used. The sensor data generated contain measured values and associated confidence values, the confidence values indicating a measure of the reliability with which a measured value is associated with a specific object, for example a roadway, a vehicle or a building. The measurement and confidence values are examined and interpreted by downstream algorithms. The result of the interpretation is then transmitted via an interface to the respective driver assistance system (FAS), which can then take over control of the vehicle operation taking into account the sensor data. As the performance of the sensors increases, the complexity of the information, ie the data density to be transmitted, continues to increase. From the DE 102 54 806 B4 such a driver assistance system is known.

The DE 10 2004 018 088 A1 describes a lane recognition system.

However, in order to be able to transmit this information to a FAS as quickly as possible via a limitedly powerful interface (e.g. CAN bus), the data must be further compressed.

Advantages of the invention

By linking different algorithms listed below, an interface is defined between the measured values detected by a sensor and the FAS, which can intervene in the vehicle control. This enables a scalable reduction of the data to be transmitted in several stages.

In a first step, the measured values that belong to a physical object are combined into an environmental region using their confidence values via adjustable thresholds. The transmission of the measured values with respective confidence for a physical object is thus reduced to the transmission of the measured values of a surrounding region with only one uniform confidence, which results, for example, from averaging the original confidence values. The surrounding regions can be represented in the form of scalar fields. Since the number and the height of the thresholds for the confidence values to be taken into account can be set, the measuring points can be combined to more or less dense surrounding regions with a confidence level each, which describe physical objects. This results in a more or less severe data reduction.

Further data compression can be achieved by approximating the contour of a resulting object area (or surrounding region) using a polygon. The conversion into a polygon can be carried out, for example, using the hair transformation described in the article by Davis, TJ: Fast Decomposition of Digital Curves into Polygons Using the Haar Transform. In: IEEE Transactions on Pattern Analysis an Machine Intelligence (PAMI) 21 (1999), August, No. 8, pp. 786-790. It is advantageous to set the number of polygon corners to adapt to the respective application and thus to be able to directly influence the accuracy of the approximation. For this purpose, less significant surrounding regions can be represented, for example, with a smaller number of polygon corners, while for the driver assistance system, more important surrounding regions can be represented with a higher number of polygon corners. The polygonization of the contours results in a considerable reduction in data, so that the most important data that the driver assistance system needs to control vehicle operation can be transmitted safely and quickly, even via limitedly powerful data channels or interfaces.

An advantageous further development of the invention provides that when the data-reduced region description is transmitted, the surrounding regions with high confidence are first transmitted to the FAS before the surrounding regions with low confidence are transmitted. This ensures that at least the most important data is securely transmitted to the FAS, especially with less efficient transmission paths. If the bandwidth of a transmission path (CAN or LAN interface) is not sufficient, the transmission could be interrupted, but the most precise information has already been transmitted.

The method according to the invention not only has the advantage that the necessary data can be safely transmitted to a driver assistance system even over limitedly powerful transmission paths, but it also has the further advantage that the driver assistance system has to take a smaller number of data into account in the further calculations . Overall, this increases the security of the entire system, since overloading the system through data reduction prevents faster calculation is made possible in the driver assistance system for carrying out the regulation of vehicle operation.

To carry out the method according to the invention, a control device can be provided, which is used between one or more environmental sensors, for example a camera, and the driver assistance system for data reduction. However, there is also the possibility that the data reduction is carried out by a computer program, specifically with program code means, for which a microcomputer upstream of the driver assistance system or quite generally a computer can be used.

The method presented is generally applicable and can be applied to data from radar and laser sensors as well as to camera systems.

Figure list

• 1 einen schematischen Aufbau eines Sensorsystems mit zugehörigem Fahrerassistenzsystem, und
• 2 das Prinzip der Schwellwertannäherung an einen Werteverlauf zur Vereinfachung der Umgebungsregionen.

The invention is explained in more detail below on the basis of an exemplary embodiment shown in the drawing for the camera-based detection of passable areas and simultaneous object detection. Show it

• 1 a schematic structure of a sensor system with associated driver assistance system, and
• 2nd the principle of threshold approximation to a value curve to simplify the surrounding regions.

Description of the embodiment

In 1 provides a sensor, which is exemplary here as a camera 10th is shown, measurement data in the form of an image 20th which are subjected to object and open space detection in a manner known per se. By evaluating the measurement data of the image 20th can, as in the picture below 21 is shown, by generating surrounding regions of uniform confidence, the measurement points are summarized. The principle of the summary is in 2nd shown. Individual vehicles 11 , 12th ( 1 ), initially consist of several sub-areas 13 , 14 , 15 , 16 (Vehicle 11 ) with measurement data whose confidence levels each exceed different threshold values. In picture 21 are the sub-areas 13 , 14 , 15 , 16 of the vehicle 11 , as well as the sub-areas 17th , 18th , 19th of the vehicle 12th , which are assigned different confidence levels, are shown with different hatches.

The subareas 17th , 18th , 19th will continue through the in 2nd shown formation of level lines summarized. Adjacent sub-areas with different confidence values can be taken into account for a new surrounding region, taking into account defined threshold values 30th ( 1 and 2nd ), which is characterized by a uniform confidence, can be summarized, for example by averaging the individual values. This first stage of data compression is in 2nd exemplary for the vehicle 12th of 1 shown.

In 1 are in picture 22 the contours of the newly emerging surrounding regions with uniform confidence, which in the example relate to part of the road and two vehicles in front, are shown with uniform hatching. The boundary points of the different surrounding regions define a characteristic contour for each surrounding region. In the following, the contours of these surrounding regions are represented by polygons with those in picture 23 Key points shown 1-1-1-1, 3-3-3-3, 6-6-6-6-6-6-6, 7-7-7-7-7-7 approximated (second stage of data compression) . It is possible to transfer only those surrounding regions that contain important data for the FAS function via the interface. This is in 1 in picture 24th in the sensor image and in image 25th shown in the vehicle coordinate system. Only the surrounding regions 1' , 3 ' , 6 ' and 7 ' transfer.

The determined contour data or contour values and assigned confidence measures are transmitted via an interface 8th to a driver assistance system 9 transmitted, which performs a control of vehicle operation based on the data evaluation.

The contour values of the surrounding region 7 ' define the vehicle in front 12th of 1 on the road and in the driver assistance system of the ego vehicle 26 evaluated to regulate driving operations. Brakes the vehicle in front, for example 12th decreases the distance between the ego vehicle 26 and the in 1 , Image 25th depicted surrounding region 7 ' , which causes the driver assistance system to reduce the speed of the ego vehicle 26 prompted.

The exemplary embodiment shown shows in FIG 1 just a sensor in the form of a camera 10th , however, additional cameras and also radar sensors or other sensors can be used individually or in combination to detect surrounding regions. In any case, according to the invention, the data determined by the sensors are subjected to data reduction in order to achieve smooth functioning and fast processing in the driver assistance system.

Claims (7)

For data reduction in the transmission of sensor data generated from environmental sensor signals of different physical properties to a driver assistance system (9), wherein the sensor data measurements and the measured values contain associated confidence values, and the physical properties can be a roadway, preceding vehicles or other objects or areas method, characterized characterized in that the measured values belonging to a physical object, the confidence values of which exceed a predetermined threshold value, are combined into a surrounding region with a uniform confidence value before they are transmitted to the driver assistance system (9), an approximation of at least one contour of a surrounding region (1 ', 3 ', 6', 7 ') by a polygon. Procedure according to Claim 1 , characterized in that the number and height of the thresholds of the threshold values is adjustable. Procedure according to one of the Claims 1 or 2nd , characterized in that the individual surrounding regions are assigned confidence values which experience a data reduction through assignment to different definable threshold values. Method according to one of the preceding claims, characterized in that the number of polygon corners and thus the accuracy of the approximation is adjustable. Method according to one of the preceding claims, characterized in that when the data-reduced region descriptions are transmitted, the regions with high confidence are first transmitted to the driver assistance system (9) before the regions with low confidence are transmitted. Device for carrying out the method according to one of the preceding claims, characterized in that a control unit used between one or more environmental sensors and the driver assistance system (9) carries out the data reduction. Computer program with program code means to perform all steps of any of the Claims 1 - 5 perform when the program is running on a computer.

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