DE102006046903A1 - Driver assistance system and method for tracking located objects - Google Patents

Abstract

Method for tracking objects (36, 38, 40) located with a locating device (12) of a motor vehicle (32), in which a distinction is made between moving objects, stationary objects (36, 38) and stopped objects (40) is classified as paused if it has not moved, but has moved in the past, characterized by the following steps: - if an object (4) is classified as paused, storing a pause zone (54) indicating the pause location of that object and, if a new, non-moving object located within a stop zone (54) is located, classifying that object as stopped.

Description

State of the art

The The invention relates to a driver assistance system for motor vehicles and a Method for tracking of located objects, in such a way Driver assistance system is implemented.

One example for a driver assistance system to which the invention applies, is a so-called ACC (Adaptive Cruise Control) system that it allows to automatically regulate the speed of a vehicle the existence directly in the own lane preceding vehicle in one safe distance is tracked. Part of this system is a Tracking device, for example, an angle-resolving Radar sensor used to locate objects ahead of the vehicle can and the distances, Relative velocities and azimuth angles of these objects measured can be. The location data of the objects are periodic using the radar sensor detected. In a procedure called "tracking," become the objects located in the current cycle of the radar sensor identified with objects that are located in previous cycles were, so that track the movements of the objects. By comparing the measured relative velocities with the absolute velocity of your own vehicle can also be the absolute speeds determine the located objects, so that between moving and standing Objects can be distinguished.

The Previously used ACC systems are only for use when traveling at relatively high speeds on highways or well-developed country roads provided in situations where the driver does not expect that this System reacts to stationary obstacles. That's why they need it Systems react only to moving objects. advanced However, ACC systems are said to operate at low speeds as well possibly even be used in city traffic and should especially the possibility offer to automatically decelerate your own vehicle to a standstill, if, for example, when driving on a jam end, the front vehicle stops. In a further expansion stage, the system should also be the automatic Restart the vehicle control when the front vehicle sets in motion again. These systems need to be able to work as well to react to standing objects.

Indeed does not represent every standing object that is expected within the is located by the own vehicle traveled driving hose, a real obstacle. For example, it may be located standing objects also to radar echoes of manhole covers or expansion joints Acting in the roadway that does not require a system reaction. The System must therefore to be able to between real standing obstacles and irrelevant ones to distinguish standing objects.

In DE 10 2005 003 194 A1 An ACC system is described in which for this purpose the located objects are classified into three categories, namely as moving objects, standing objects and stopped objects. The suspended objects are objects whose instantaneous absolute velocity is close to zero, but which in the past were once classified as moving objects. If z. If, for example, a vehicle in front stops, this vehicle, as long as it is stationary, is classified as a stopped object. These suspended objects are taken into account in the scheme, while objects classified as "standing" are ignored as irrelevant bogus obstacles.

Under certain circumstances However, it may happen that a Object classified as a suspended object, that is one represents an obstacle to be considered, in the course of the tracking procedure temporarily is lost and then re-located again. This object is then interpreted as a newly occurred object when re-locating, via whose History is unknown. Consequently, this new object, since it seems the absolute speed is zero right from the start has, classified as a standing object, though it is in truth is a relevant obstacle.

A Such a situation may occur, for example, when a driver is driving ahead Vehicle at about the same height with a stationary object, for example a traffic sign or a parked at the edge of the road vehicle stops, so that the radar sensor for both Objects the same distance and the same relative speed measures. In this situation is common from the following establish the angular resolution of the Radar sensor so far lowered that the two objects not more can be distinguished.

The azimuth angle of a radar target is determined based on the differences between the amplitudes and / or phases of radar signals originating from the same object and received by different receiving elements of the radar sensor. The radar sensor used is usually an FMCW radar, in which the frequency shift of the received radar echo depends both on the distance and on the relative speed of the object. In general, it can therefore be decided based on the frequency of the received signals whether two signals originate from the same object or from different objects. However, if both objects are at rest, and thus have the same relative velocity, and are also coincidentally at the same distance, the signals can no longer be distinguished by frequency, and it can not be determined with certainty whether the received signals from two different objects are different Azimuth angles or originate from a single extended object.

The Determination of the azimuth angle and thus the identification of the located objects with the earlier located objects is then subject to considerable uncertainties, and it may therefore happen that the Radar echo received from the stopped vehicle, now falsely with the stationary object (road sign or parked vehicle) identified becomes. For The location system then looks as if the stopped vehicle merged with the stationary object and thus as an independent object disappeared. If then due to the self-motion of the equipped with the ACC system Vehicle the distance conditions change again, the stopped vehicle appears as a new, stationary object.

A another situation in which there is a temporary loss of property can, is that in front of the immediately preceding vehicle, which is part of the Distance control is tracked as a target, in the same lane another vehicle is located. First of all, this one too can Vehicle can be located by the radar system, such as when the vehicles drive a bit staggered to each other or because the mostly relatively deep, in height the bumper arranged radar sensor under the immediately preceding vehicle can "see" through it. Frequently becomes also makes it possible to locate that the Radar rays on the road surface below the immediately preceding Vehicle are reflected.

It However, it can also happen that the next but one vehicle temporarily completely shadowed by the immediately preceding vehicle becomes. Now, if the first of the three vehicles stopped, then is lost due to such shadowing effect and afterwards is again located by the radar sensor, for example, because the immediate preceding vehicle is embarrassed on an adjacent lane, so will The stopped vehicle, in turn, falsely as a stationary object classified and ignored in the distance control.

By The situations described above thus lead to misinterpretations and malfunction of the ACC system, which irritate the driver and his confidence in reliability undermine the system or even lead to rear-end collisions.

Disclosure of the invention

task The invention is a method and a driver assistance system to create a more reliable one Classification of held objects allowed.

These The object is achieved by the in claim 1 specified method and by a driver assistance system solved, where this method is implemented.

at the method according to the invention When an object is classified as suspended, it becomes a stop zone stored indicating the stopping location of this object. When a new, non-moving object is located, so it is checked whether this object is located within one of the saved stopping zones, and if so, the object, albeit over its Prehistory is not known, however, as a stopped object classified.

pictorially spoken "remembers" the system of the invention the place where a vehicle in front stopped, even if this stopped object itself in the course does not follow the tracking procedure. If then at the same If a new object appears, it automatically becomes with the Identified lost object identified. To this Way can be especially in the situation described above, the existence stopped vehicle, even after temporary loss of property is classified as a stopped object, so that the driver assistance system can respond appropriately to this object.

advantageous Embodiments and development of the invention are specified in the subclaims.

Preferably, the stopping zone is a rectangular horizontal surface which is dimensioned in length and width so that the stopped object can be recognized despite certain uncertainties in the determination of the distance and the lateral position. For example, this rectangle has a width of about 1✝m and a length of about 2 m, and thus their dimensions are approximately of the same order of magnitude, but are slightly smaller than the plan of a conventional car. According to a development, the dimensions and the shape of this stopping zone can also be varied depending on the distance, the roadway direction or other factors that influence the accuracy with which the distance and the azimuth angle or the lateral position of the ob can be measured.

The inventive method can be used as a software algorithm for be an electronic data processing system implemented that too the others Functions of the driver assistance system controls. Preferably the algorithm so that for each persistent object one Data structure is created or "opened" that the data the relevant stopping zone. These data will be useful specified in a vehicle-fixed coordinate system, but then have to continuously updated according to the self-motion of the vehicle so that the stopping zone with respect to the roadway stationary remains. This update, ie tracking the stop zone, will continue even if the stopped object containing this Stop zone is lost. If also the object itself can still be located and then results from the location data, that yourself the object starts moving again, then the corresponding stop zone (Data structure) deleted, and the object itself becomes like a normal moving object again treated. Preferably, the stopping zone is deleted even if the own vehicle has passed the place of this stopping zone, d. h., if the own vehicle has crossed this zone or at this zone has passed.

ever according to traffic conditions several stop zones simultaneously. In that case, if a new stationary object is located, the position of this object compared with all stopping zones, and if the object is in at least one of these stopping zones lies, it is considered a stopped object classified.

Brief description of the drawings

One embodiment The invention is illustrated in the drawings and in the following Description closer explained.

It demonstrate:

1 a block diagram of a driver assistance system according to the invention;

2 and 3 Sketches of different traffic situations in which the method according to the invention is used; and

4 and 5 Flow charts for explaining the method according to the invention.

In 1 is an example of a driver assistance system in a motor vehicle, an ACC system shown, the electronic data processing device 10 and a built-in locator in the vehicle 12 includes. At the locating device 12 it is, for example, an angle-resolving radar sensor, such as an FMCW radar sensor, with which the apron of the vehicle is monitored. The periodically from the locator 12 detected raw data are sent to the data processing device 10 transmitted and there in an evaluation unit 14 so that you get a list of the distances, relative velocities and azimuth angles of all located objects. From the distances and azimuth angles, it is also possible to determine the lateral positions of the objects, that is to say the coordinates in the direction perpendicular to the direction of travel of the vehicle. The data received in each measurement cycle is sent to a tracking module 16 transmitted, with which the movements of the individual objects are pursued.

A speed sensor 18 provides the speed V of the "own" vehicle, ie, the vehicle equipped with the driver assistance system. By comparing the measured relative velocities of the objects with the velocity V, the absolute velocities of the objects can also be determined so that it is possible in particular to distinguish between stationary objects and moving objects. This happens in a classification module 20 in which, among other things, a directory 22 all moving objects is guided. If a vehicle traveling directly in the lane traveled by the own vehicle is located among the moving objects, this vehicle is selected as a target for the distance control, and the dynamic data of this object are sent to a controller 24 pass on the basis of this data in the drive system 26 and, if necessary, the braking system 28 of the vehicle to control the speed of the vehicle so that the target object is tracked at an appropriate distance.

If one of the preceding vehicles stops, this is indicated by the fact that the absolute speed of this vehicle decreases to zero. When it reaches approximately zero, the object that was previously considered a moving object is reclassified to a "suspended" object. Accordingly, the classification module contains 20 also a directory 30 of suspended objects.

If the target object stops, is by the controller 24 also the own vehicle braked in the state, so that it comes to rest at an appropriate stopping distance behind the target object. When the target object starts moving again, it is reclassified to a moving object and, if necessary, the controller can 24 also the automatic restart control of the own vehicle, if not too long a time span has elapsed since the stopping process and if there are no other stationary or moving obstacles in front of the vehicle.

As a standing obstacles are from the controller 24 only objects that are in the directory 30 are listed as held objects. Radar targets that were recognized as standing objects from the start and never moved later are, on the other hand, ignored by the ACC system. In this way, the data processing effort is kept within limits and at the same time avoided that radar echoes of objects such as manhole covers, expansion joints or smaller objects that are on the road, are misinterpreted as obstacles. In general, in the applications for which the ACC system is intended, it is unlikely that real obstacles will be permanently on the road. In exceptional cases, such as when driving on a jam end, it may happen, however, that the vehicle that forms the end of the jam, already stands when it first came from the locating device 12 is detected. In this case, this stationary vehicle would not be recognized as an obstacle and would not trigger a system response. In this situation, intervention by the driver would therefore be required.

On the other hand, would however, for example B. pedestrians or other obstacles that arise during of a traffic jam into the area in front of your own vehicle have, either as moving objects or as stopped objects classified and thus recognized as an obstacle.

In the directory 30 it also lists paused objects that are in a side lane. Therefore, if the driver of the own vehicle makes a lane change just before reaching the tail end, a stopped object existing on the new lane may be selected as the target object.

However, situations in which an object that was once classified as a suspended object are temporarily lost are problematic. An example of such a situation is in 2 illustrated. One with the tracking device 12 and the associated ACC system equipped vehicle 32 drives on a roadway 34 , on the right side of the road several parking vehicles 36 . 38 located, which are recognized by the ACC system as a stationary object and thus are ignored in the control. In front of the "own" vehicle 32 drives a vehicle 40 , which is the target object for the distance control.

It should now be assumed that the vehicle 40 at about the height of the vehicle 38 stops. The tracking device 12 then measures for the two vehicles 38 . 40 the same relative speed and also approximately the same distance. In the in 2 The situation shown is the distance of the vehicle 40 a little bigger than the vehicle 38 , However, because your own vehicle 32 is still moving, will be in the further course due to the larger cross-shelf of the vehicle 38 reverse the distance ratio. As a result, at some point a time is reached at which also the distances between the two vehicles 38 . 40 are so similar to each other that the frequencies of the radar returns obtained from these vehicles can no longer be distinguished. The two vehicles 38 . 40 then appear for the locator 12 like a single, relatively old object, and the azimuth angle measured for that object is not sharply defined. It depends on the specific configuration of the reflective surfaces on the backs of the vehicles 38 . 40 relative to the locating device 12 and the ratio of the backscattered intensities, which value is determined in detail for the azimuth angle. From the perspective of the tracking module 16 Therefore, this process can be represented as if the reflex point, so far the vehicle 40 has represented to the vehicle 38 wander and get into its reflex point.

The consequence is that the vehicle 40 from the directory 30 of the suspended objects is deleted. At a later point in time is then for the vehicle 40 measured distance is much smaller than the distance of the vehicle 38 that the two objects can be distinguished again. The tracking module 16 then recognizes at the location of the vehicle 40 a new object that can not identify it with any of the objects you tracked earlier. Since this object is not moving, it is now ignored as a standing object.

The driver of the vehicle 32 however, the ACC system would expect the vehicle 40 recognizes as a persistent vehicle and triggers a corresponding stopping process for the own vehicle. Only relatively late would the driver recognize that the ACC system fails in this case because it is the vehicle 40 mistaken for a standing object and not for a stopped object.

It can also have a similar effect in the 3 illustrated situation come. Here follows the vehicle equipped with the ACC system 32 a vehicle serving as a target object 42 , before in the same lane still another vehicle 44 moves. Because of the tracking device 12 emitted and received again radar beam 46 on the road surface 48 is reflected and so does the vehicle 44 achieved, both vehicles can 42 and 44 be located. As long as these two Vehicles are moving, they are listed as moving objects in the directory 22 guided.

If now the first vehicle 44 it is reclassified to a paused object and placed in the directory 30 guided. If now the vehicle 42 closer to the stationary vehicle 44 the radar beam can 46 be interrupted so that the tracking module 16 the vehicle 44 can not pursue anymore. Consequently, this vehicle would be deleted from the list of stopped objects. If now the vehicle 42 On a side lane, the vehicle can 44 are suddenly rediscovered, and it is now interpreted by the tracking module as a new, stationary object. After the vehicle 42 cleared the way, that would be the regulator 24 not on the vehicle 44 but an acceleration of the vehicle 32 cause. Here too, a situation occurs in which the system behavior does not meet the expectations of the driver of the vehicle 32 corresponds and the driver must react relatively quickly to avert a rear-end collision.

Regarding 4 and 5 A method will now be described which avoids such critical situations.

4 shows a program routine executed by the data processing device 10 in 1 is executed and the classification module 20 can be assigned. This program routine manages a directory 50 of stopping zones that represent the positions of suspended objects even if those objects themselves can no longer be located.

The program routine after 4 is executed periodically for each moving object that is in the directory 22 is registered. In step S1 it is checked whether the relevant object has come to a standstill. If this is not the case, step S1 is repeated cyclically. If the object is no longer moving, it is reclassified to a suspended object in step S2 and placed in the directory 30 added. In addition, in step S2, in the directory 50 a stop zone 54 generated and saved in 2 is shown graphically. This stopping zone is a horizontally oriented rectangular area about 1 m wide and about 2 m long, which faces the point of reflection, ie the presumed location of the object in question 2 of the vehicle 40 , is centered.

In the in 2 The example shown is the stopping zone 54 with its longitudinal axis parallel to the longitudinal axis of the "own" vehicle 32 oriented. However, since in an ACC system usually the road curvature is taken into account, for example, based on the yaw rate of the own vehicle, so that a correct lane allocation of the located objects can be made, it is also possible in a modified embodiment that the stopping zone 54 is oriented with its longitudinal axis parallel to the local roadway course.

In the register 50 becomes the stopping area 54 For example, represented by the coordinates of their center and by their length and width. The length and width can optionally also vary depending on the distance and the azimuth angle or the lateral storage of the object in question.

According to 4 is then checked in step S3, whether the object has set in motion again, ie, whether it is reclassified again from a stopped object to a moving object. If this is the case, the stop zone is deleted again in step S4. Subsequently, the program is terminated. Since the object is now again a moving object, the in 4 However, the routine shown immediately started again for this object.

If the check in step S3 has shown that the object is still standing, in step S5, the stop zone 54 tracked. This means that the coordinates of the stopping zone according to the self-motion of the vehicle 32 be tracked that the stopping zone stationary with respect to the road 34 remains. Optionally, also the length and width of the stopping zone 54 be adapted according to the changes in the distance and the azimuth angle of this stopping zone.

Subsequently, it is checked in step S6 whether the own vehicle 32 has passed the stop zone. If this is not the case, so if the stop zone before the own vehicle 32 is returned to step S3, and the above-described steps S3 to S6 are repeated. Is, however, the own vehicle 32 in the meantime passing by or passing over the stopping zone, the program branches from step S6 to step S4, the stop zone is cleared, and the routine is ended. In this way it is ensured that the number of stopping zones in the directory 50 does not grow beyond all limits.

In the 5 The routine shown is also periodically from the data processing device 10 executed. In step S10 it is checked whether the locating device 12 has located a new stationary object, ie an object with the absolute speed zero. If this is not the case, the step S10 is repeated cyclically. If a new stationary object has been located, it is checked in step S11 whether this object is in at least one of the stops located in the directory 50 are listed. If so, the object is classified as a suspended object in step S11 and placed in the directory 30 although this object has never moved since its first appearance. Then the routine is ended. If the result of the query in step S11 is negative, step S12 is skipped, and the routine is terminated immediately, that is, the new object is classified as a stagnant object and left out of consideration.

The effect of the interplay of in 4 and 5 shown routines will now be based on 2 be explained. As long as the vehicle 40 has not stopped yet, it will be in the directory 22 as a moving object. If the vehicle 40 this is detected in step S1, and in step S2 the object is placed in the directory 30 recorded, and the stop zone 54 is generated. Then the vehicle likes 40 due to the lack of angular resolution of the locating device 12 get lost so it's out of the directory 30 is removed, but the stop zone remains 54 in a sense as the shadow of this object. If the tracking device 12 determines that the vehicle 40 is set in motion again, the stop zone 54 deleted in steps S3 and S4. Otherwise, the stop zone remains 54 persist until they get off the vehicle 32 happened.

When the vehicle 32 the vehicle 40 and the stop zone 54 approaching and then the vehicle 40 is located again while this vehicle is still standing, so the steps S10 to S12, that the vehicle 40 again as a paused object in the directory 30 is recorded. Consequently, the controller can 24 on the vehicle 40 react as the driver of the vehicle 32 expected.

In an analogous manner, the method described above also in the 3 the situation shown sure the regulator 24 appropriate to the vehicle 44 responding.

Claims (9)

Method for tracking with a locating device ( 12 ) of a motor vehicle ( 32 ) located objects ( 36 . 38 . 40 . 42 . 44 ), between moving objects, standing objects ( 36 . 38 ) and paused objects, where an object is classified as paused if it has not moved but has moved in the past, characterized by the following steps: - if an object is classified as paused, storing a pause zone ( 54 ), which indicates the stopping place of this object, and - when a new, non-moving object located within a stopping zone ( 54 ) classify this object as paused. Method according to claim 1, characterized in that the stopping zone ( 54 ) is defined as a plane lying in a horizontal plane containing the location where the object ( 40 ) at the time it stopped. Method according to claim 2, characterized in that the stopping zone ( 54 ) is a rectangle. Method according to claim 2 or 3, characterized in that the geometry and / or the size of the stopping zone ( 54 ) depending on the position of the stopping zone relative to the locating device ( 12 ) is varied. Method according to one of the preceding claims, characterized in that a directory ( 50 ) of all stored stopping zones ( 54 ) to be led. Method according to claim 5, characterized in that a stopping zone is again removed from the directory ( 50 ) is deleted when the corresponding object is set in motion. Method according to claim 5 or 6, characterized in that a stopping zone from the directory ( 50 ) is deleted when the vehicle ( 32 ) happened. Driver assistance system for motor vehicles ( 32 ), with a locating device ( 12 ) for locating objects ( 36 . 38 . 40 . 42 . 44 ) in advance of the own vehicle ( 32 ) and a data processing device ( 10 ), which engages in the vehicle guidance depending on the locations and / or states of movement of the located objects, characterized in that the data processing device ( 10 ) is adapted to carry out the method according to one of claims 1 to 7. Driver assistance system according to claim 8, characterized in that the driver assistance system is a distance control system which is designed to be limited to moving or stopped objects ( 40 . 42 . 44 ) and your own vehicle ( 32 ) to brake when an immediately preceding vehicle located as an object ( 40 ) stops.