DE102008007350A1 - Driver assistance method and apparatus based on lane information - Google Patents

Abstract

The invention relates to a driver assistance method and a device based on lane information, driver information and / or action being triggered depending on the lane information, and the lane information being derived from at least two information characterizing the lane 10, this information being provided by means of one particular at least one video sensor comprehensive on-board sensor system is obtained. In order to accurately detect the curvature of the lane 10, discrete shape points 1.1, 1.2, 1.3, XPO, XP1, 1.n assigned to the roadway 1 and the curvature values assigned to the respective shape point are taken from a digital map of the lane 10. The curvature of the lane 10 is determined by merging the data obtained from the on-board sensor system of the vehicle 2 with the data taken from the digital map.

Description

The The invention relates to a driver assistance method and apparatus, that work on the basis of lane information.

State of the art

Driver assistance systems that operate based on lane information are known in the art. An example of such a driver assistance system is a warning system that warns the driver when they accidentally leave the lane. Such a system is for example off EP 1074430 A1 known. It describes how with image sensors, the road on which the vehicle is moving, is detected and the driver is warned when the vehicle leaves or threatens to leave the detected lane. Also from the patent applications DE 103 11 518.8 and DE 102 38 215.8 Such driver assistance systems are known. For detecting the lanes image sensor systems are used in the known systems, which are installed in the vehicle and record the lying in front of the vehicle traffic area. From images of the lane markings, the boundaries of the lane and thus its course are derived. The detection of the lane therefore depends heavily on the prevailing visibility conditions. In poor visibility conditions, the systems are often not reliable enough and are switched off so as not to endanger the driver.

Out DE 103 49 631 A1 Furthermore, a driver assistance method is known in which data of a global positioning system and / or data of a navigation map are used to check the plausibility of the lane course recorded by onboard sensors. This is intended to ensure that the course of the lanes can be detected more reliably even in poor visibility conditions and the driver assistance process longer available to the driver for his support and does not need to be shut down early.

digital Maps, as previously used in onboard navigation systems for route guidance increasingly gaining acceptance for driver assistance and security systems in importance, since both the quality the map data as well as the information density constantly increase and have now reached a level that in connection with future development of driver assistance functions, especially for vehicle guidance, new possibilities provides for the detection of the vehicle environment. For example was part of the publicly funded project PREVENT, subproject MAPS & ADAS, a concept designed as Driver Assistance Functions (ADAS) a standardized interface (ADASIS) on data of a digital Map (MAPS).

Out DE 101 37 292 A1 is a method for operating a driver assistance system of a vehicle, in particular motor vehicle, with a power-assisted steering known.

• – Erfassen oder Abschätzen von Umgebungsdaten einer, vorzugsweise momentanen, Verkehrssituation,
• – Erfassen oder Abschätzen von, vorzugsweise momentanen, Bewegungsdaten des Fahrzeugs,
• – Vergleichen der erfassten oder abgeschätzten Umgebungsdaten mit den Bewegungsdaten des Fahrzeugs,
• – Änderung der Unterstützung einer Lenkhandhabe nach Maßgabe des Vergleichs.

This process is characterized by the following steps:

• Acquiring or estimating environmental data of a preferably current traffic situation,
• Detecting or estimating, preferably momentary, movement data of the vehicle,
• Comparing the detected or estimated environmental data with the movement data of the vehicle,
• - Change of support of a steering handle according to the comparison.

Out DE 10 2005 048 014.4 Further, a driver assistance system with a lane keeping function is known, which comprises a device for the recognition of lanes on the road and a control device for engaging in the steering system of the vehicle in the sense of tracking. Furthermore, the driver assistance system comprises means for detecting the position of the vehicle with respect to the edges of the lane, as well as means for detecting a cornering of the vehicle. The control device exercises its control function in dependence on the position of the vehicle on the lane and in dependence on a cornering of the vehicle.

Disclosure of the invention

Advantageous effects

The invention enables a further improvement of the operational safety in a driver assistance method. The solution according to the invention even allows a reliable guidance of the Vehicle with the driver assistance method, if the course of the traveled by the vehicle lane can not be readily detected with an on-board sensor system, in particular video sensor. This is the case, for example, when, as a result of poor visibility conditions or as a result of occlusion, the markings of a lane can no longer be reliably detected by the sensor. Even with completely missing markings of the lane, the invention can still contribute to a reliable guidance of the vehicle. Even under unfavorable conditions, the driver assistance procedure is therefore longer available to the driver. As good as possible, the course of a lane and the respective position of the vehicle on this are recorded by means of the on-board sensor. From a digital map of the traffic area, the roadway or lanes characterizing shape points and the curvatures associated with these shape points are then additionally taken. Particularly advantageously, the curvature at the current position of the vehicle between two shape points is determined by adding to the curvature of a shape point the difference of the curvatures of the curvature of the vehicle between them that includes the path length ratio. The path length ratio is the quotient of the path length between the first shape point and the current position of the vehicle and the path length between the two shape points enclosing the vehicle between them. Advantageously, the course of the lane between two adjacent shape points can be approximated by a curve, in particular a cubic polynomial, whose start and end curvature coincides with the curvatures in the two adjacent shape points. With sufficiently small distances between the shape points, for reasons of simplification, the path lengths on the lane can advantageously also be approximated as distances.

Especially advantageous is an interface to a vehicle management function executive module at which the calculated curvature the lane or the lane and the position of the vehicle within the lane is provided. The vehicle management function then determines interventions on the basis of these values in a known manner in longitudinal and / or transverse guidance of the vehicle or Warning signals.

Further Advantages emerge from the subclaims, the description and the drawing.

Brief description of the drawings

embodiments The invention will be described in more detail below with reference to the drawing explained. Showing:

1 the representation of a lane course by so-called shape points and bends in a digital map;

2 a view of a traffic area with a vehicle;

3 a diagram for explaining the provision of data for the driver assistance method;

4 a diagram showing the interpolation and extrapolation of curvature values between shape points from a digital map.

Embodiments of the invention

Embodiments of the invention are explained in more detail below with reference to the drawing. The invention is based on the recognition that the reliability of a driver assistance method, in particular even in poor visibility conditions, can be significantly improved by using data from a digital map in order to record the course of a lane. In general, systems for vehicle guidance, in particular systems for transverse guidance of a vehicle, such as LKS (LKS = Lane Keeping Support), require information about the lane in front of the vehicle in the direction of travel and its course, in particular the curvature of the lane. According to solutions known from the prior art, the curvature is determined by detecting the lane markings with an on-board sensor system, in particular a video camera, and processing the acquired data in an image processing device. Many future driver assistance functions require a sufficiently large look ahead for the detection of lane information. In purely video-based systems, it is often the case that this look ahead is not given. For example, as a result of missing lane markings or, due to occlusion or unfavorable weather or lighting conditions, poorly visible lane markings. The use of data from digital maps proves to be advantageous because the information stored in these maps is significantly reduced higher foresight and high availability and accuracy are available a priori. Even in the foreseeable future, these advantageous properties will not be able to achieve a board-based autonomous sensor system, such as a video or radar sensor, even under optimal conditions, since their range is inherently limited.

In current digital maps available today, the course of lanes is stored in the form of nodes, so-called "shape points", where each shape point is assigned the attribute radius R or the curvature as an inverse value κ = 1 / R below, with reference to 1 , explained. 1 represents the course of a roadway 1 in a digital map. In a digital map, the course of the road 1 through discrete shape points 1.1 . 1.2 . 1.3 , X _P0 , X _P1 1.n marked, which are arranged at a distance from each other. In the traffic area 100 a vehicle is moving 2 on the roadway 1 , As already mentioned, at least one attribute is assigned to each shape point, in particular the radius R of the roadway in the respective shape point or the curvature as its inverse value. Unfortunately, at present and for the foreseeable future, it is unlikely that the markings 10a . 10b a lane 10 on the roadway 1 , in addition to the already mentioned shape points, will also be available in a digital map. A positioning of the vehicle 2 on the lane 10 and thus a determination of the relative position of the vehicle 2 in relation to the lane 10 Therefore, with the help of a digital map based on a global positioning system, such as GPS in particular, will not be readily possible because the position accuracy of GPS is not sufficient. An on-board sensor system comprising, for example, at least one video sensor, however, is quite able to determine both the course of a lane and the relative position of the vehicle with respect to this lane. This will be explained below with reference to 2 explains that a supervision of a traffic area 100 shows. In the traffic area 100 the vehicle is moving 2 on a lane 10 , The lane 10 is of marks 10a . 10b limited. In the digital map is the course of the roadway 1 through the already mentioned shape points 1.1 . 1.2 . 1.n marked. The respective radius in each shape point is designated R1.1, R1.2, R1.n. The location of the vehicle 2 relative to the lane 10 the roadway 1 is characterized by the distances dy _left and dy _{right of} the vehicle 2 in terms of the markings 10b . 10a of the lane 10 , as well as the angles ψ _left and ψ _right between the longitudinal axis L of the vehicle 2 and the tangents X _left and X _right to the lane markings 10b . 10a at the level of the origin of the coordinate system of the vehicle 2 , The on-board sensor system could also include bends in the lane 10 to capture. For the reliable detection of existing bends, however, a certain foresight range of the sensor system is required, which unfortunately is not always the case. In addition, the curvature of the lane determined using standard estimation methods 10 deviate from the real curvature and therefore gives the real course of the lane 10 only limited again. In contrast, the curvatures of the roadway stored in current digital maps 1 oscillation and noise free. The invention now uses both types of data to the course of the lane 10 to record as reliably as possible. This will be further discussed below with reference to 3 in which a diagram for explaining the provision of data for the driver assistance method is shown. The diagram schematically illustrates an on-board driver assistance device 300 for the collection of data, their processing and subsequent forwarding to other on-board systems, which are used in particular for vehicle guidance. The device 300 includes a functional module 30 "Navigation system", the vehicle by means of a digital map and a GPS receiver 2 a location allows. In this way, the position and orientation of the vehicle 2 be determined on a roadway. Furthermore, with the function module 30 the roadway 1 associated shape points and the each shape point associated curvature are determined. These data are via an interface 30.1 for one with the function module 30 connected functional module 32 provided. The device 300 further includes a functional module 31 , This is an on-board sensor system comprising at least one video sensor, preferably at least in the direction of travel in front of the vehicle 2 lying vehicle environment detected in order there in particular markings 10a . 10b of the lane 10 to detect. In addition to the detection of such markings 10a . 10b can by means of the function module 31 also the relative position of the vehicle 2 in terms of these marks 10a . 10b be determined. The of the functional module 31 collected and processed data is transmitted via an interface 31.1 to that with the function module 31 connected functional module 32 transmitted. In the function module 32 finds a processing of it over the interfaces 30.1 and 31.1 supplied data instead. This will initially determine the location of the vehicle 2 relative to the lane 10 from the relative position of the vehicle 2 in relation to the two of the video sensor of the functional module 31 detected marks 10a . 10b of the lane 10 determined. In the special case of parallel markings 10a . 10b This can be done, for example, by averaging the distances and angles between the axes of the vehicle-fixed coordinate system x, y and the markings 10a . 10b of the lane 10 respectively. This results in the lateral position of the vehicle 2 relative to the middle of the lane 10 : y veh, lat = 0.5 · (dy left + dy right ), (1) and the mean angle from the two tangents to the markers 10a . 10b of the lane 10 : Ψ veh = 0.5 · (Ψ left + Ψ right ). (2)

c₀

= Krümmung

c₁

= Krümmungsänderung

l

= Bogenlänge.

For calculating the curvature of the lane 10 Then, in a following step, the shape points and the radii or curvatures assigned to the respective shape points are used, which can be taken from the digital map. Since the shape points are not stored in arbitrary density in the digital maps, but are present only as discrete values and therefore also the curvatures associated with the shape points are only occasionally present, it is, for the purpose of the most accurate possible detection of the course of the lane 10 it is advantageous to provide interpolation between the bends. This interpolation takes place as a function of the distance of the vehicle 2 to the shape points, between which the vehicle 2 is in the current time step. According to the Road Parting Line Design Guidelines (RAS-L), the course of a roadway is constructed of segments of a clothoid, and a clothoid is defined as: c = c 0 + c 1 l, (3) With

c ₀

= Curvature

c ₁

= Curvature change

l

= Arc length.

Since the curvature changes linearly with the length of the arc, it is expedient to interpolate linearly within a segment of the clothoid between the curvature values taken from the digital map. This will be described below with reference to the in 4 illustrated diagram 400 explained. In the diagram 400 the curvature is shown as a function of the path s. Discrete points mark the shape points stored in the digital map 1.1 . 1.2 . 1.3 . 1.n Within a segment a of the clothoid, according to the invention, a linear interpolation is carried out between the curvature values. This is illustrated by a solid line A, which connects the individual shape points.

In the area of the boundaries b of a segment of the clothoid, such interpolation does not lead to a satisfactory result. In these areas, it is useful to extrapolate the curvature values by inserting additional so-called "virtual" shape points at the intersections of the extrapolated curvature 4 such virtual shape points are denoted by the reference numerals V1.1, V1.2, V1.3. The extrapolated course of the curvature is indicated by the curves B shown in dashed lines.

The actual determination of the curvature of the lane 10 in relation to the current position of the vehicle 2 will now be referred to again below 1 explained. When the vehicle 2 (or the zero point of the vehicle-fixed coordinate system) at the position X _veh between the two shape points X _P0 and X _P1 with the respective curvatures κ _P0 = κ (X _P0 ) and κ _P1 = κ (X _P1 ), then results the curvature in the origin of the vehicle-fixed coordinate system to:

mit:

s_0v

= Weglänge zwischen dem shape point X_P0 und der aktuellen Position des Fahrzeugs X_veh;

s₀₁

= Weglänge zwischen den beiden shape points X_P0 und X_P1.

In this mean:

With:

s _0v

= Path length between the shape point X _P0 and the current position of the vehicle X _veh ;

s ₀₁

= Path length between the two shape points X _P0 and X _P1 .

In the interests of the most accurate determination of the curvature to the current position of the vehicle 2 becomes the course of the lane 10 between the two said shape points described as a curve whose start and end curvature with the curvatures in the two shape points X _P0 and X _P1 given is. The following cubic polynomial describes the course of the lane 10 between the given shape points sufficiently precise: y (x) = a 0 .x 3 + a 1 .x 2 + a 2 · X + a 3 , (6) With xε [0 ... Δx], (7) where: Δx = x P1 - x P0 , and (8) Δy = y P1 - y P0 (9)

And the coefficients:

The determination of the arc lengths is made according to the following relationship:

In this case, the x-coordinate of the instantaneous position of the vehicle X _veh is used to determine the path length s _0V for x, and the x-coordinate of the shape points P _{1 is} used for the determination of the path length s ₀₁ .

With small distances between the shape points, the path lengths can advantageously be approximated as distances as follows:

As can be seen from the in 3 shown block diagram, the determined from the video-based detection position of the vehicle 2 within the lane 10 and the curvature κ _{veh of} the lane determined from the information from the digital map 10 via an interface 32.1 to a functional module 33 transmitted, which is the lateral guidance of the vehicle 2 affected. The location of the vehicle 2 is determined by y _{veh, lat} and Ψ _veh .

In One embodiment is the calculation of the curvature the lane or the lane without determining the lateral Position of the vehicle in the lane by means of a video system performed.

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• EP 1074430 A1 [0002]
• - DE 10311518 [0002]
• - DE 10238215 [0002]
• - DE 10349631 A1 [0003]
• - DE 10137292 A1 [0005]
• - DE 102005048014 [0007]

Claims (15)

Driver assistance method on the basis of lane information, wherein depending on the lane information driver information and / or an action are triggered, and wherein the lane information from a lane ( 10 ) indicative information, characterized in that in order to accurately detect the curvature of the lane ( 10 ) or the roadway the lane ( 10 ) or the lane ( 10 ) comprehensive roadway ( 1 ) associated discrete shape points ( 1.1 . 1.2 . 1.3 , X _P0 , X _P1 , 1.n ) and the respective shape point associated curvatures from a digital map of the road ( 1 ) and that the curvature of the lane ( 10 ) or the roadway is determined from the data taken from the digital map. Method according to claim 1, characterized in that that this information by means of a particular at least one Video sensor comprehensive on-board sensor system is obtained. A method according to claim 1 or 2, characterized that an interface is provided over which the curvature and / or a position derived from the information of the video sensor transmitted to a driver assistance function module again becomes. Driver assistance method according to claim 1, characterized in that the lateral position of the vehicle ( 2 ) with respect to the center of the lane ( 10 ) is determined according to the following relationships: y veh, lat = 0.5 · (dy left + dy right ), (1) Ψ veh = 0.5 · (Ψ left + Ψ right (2) with y _{veh, lat} = lateral position of the vehicle, dy _left = distance of the vehicle from the marking, dy _right = distance of the vehicle from the marking, Ψ _veh = angle of the vehicle, Ψ _left = angle of the tangent, Ψ _right = angle of the vehicle Tangent. Method according to one of the preceding claims, characterized in that the course of the lane ( 10 ) is approximated by a clothoid, and that the curvature of the lane ( 10 ) in relation to the current position of the vehicle ( 2 ) is determined according to the following relationship:

where:

s _0v = path length between the shape point X _P0 and the current position of the vehicle X _veh , s ₀₁ = path length between the two shape points X _P0 and X _P1 , κ _Xveh = curvature of the lane at the location of the vehicle, κ _P0 = curvature of the vehicle Lane at the shape point X _P0 κ _P1 = curvature of the lane at the shape point X _P1 . Method according to one of the preceding claims, characterized in that the course of the lane ( 10 ) between two adjacent shape points (X _P0 , X _P1 ) is approximated by a curve whose start and end curvature coincides with the curvatures in the two adjacent shape points (X _P0 , X _P1 ). Method according to one of the preceding claims, characterized in that the course of the lane ( 10 ) is approximated by a cubic polynomial according to the following relationship: y (x) = a 0 .x 3 + a 1 .x 2 + a 2 · X + a 3 , (6) With xε [0 ... Δx], (7) where: Δx = x P1 - x P0 , and (8) Δy = y P1 - y P0 , (9) with the coefficients:

Method according to one of the preceding claims, characterized in that in the case of a curved lane ( 10 ) the arc length is determined according to the following relationship:

wherein for determining the path length (s _0V ) for x, the x-coordinate of the current position of the vehicle (x _veh ) and for the determination of the path length (s ₀₁ ), the x-coordinate of the shape points (X _P1 ) is used. Method according to one of the preceding claims, characterized in that, with small distances between the shape points, the path lengths on the lane ( 10 ) are also approximated as routes according to the following relationships:

Method according to one of the preceding claims, characterized in that the determined from the video-based lane detection position of the vehicle ( 2 ) within the lane ( 10 ) as well as the curvature of the lane determined from the data of the digital map ( 10 ) are transmitted via an interface to an on-board system responsible for vehicle guidance. Method according to one of the preceding claims, characterized in that curvature values of the curvature between two adjacent shape points in particular linearly interpolated become. Method according to one of the preceding claims, characterized in that when displaying the lane course in the form of a clothoid at segment boundaries of the clothoid segments virtual shape points are inserted to an approximate Illustration of the curvature between adjacent shape points to enable. Driver assistance device ( 300 ) based on lane information comprising - a functional module ( 30 ) with a digital map of the vehicle ( 2 ) traffic volume, - a functional module ( 31 ) for the video-based recording of the traffic area ( 100 ) - a functional module ( 32 ) for determining the curvature of the road or the lane and the position of the vehicle in the lane of the functional modules ( 30 . 31 ) provided data. Driver assistance device according to claim 11, characterized in that the functional module ( 32 ) via an interface ( 32.1 ) with one for the guidance of the vehicle ( 2 ) functional module ( 33 ) connected is. Interface of a function module 33 a driver assistance function, via which the function module on the basis of map data determined curvature data of the road or the lane and a position of the vehicle in the lane or the lane is supplied.