DE102016122031A1 - Resource-saving map for a driver assistance system of a motor vehicle - Google Patents

Abstract

Method for operating a driver assistance system (2) of a motor vehicle (1), comprising a) providing a map (7) representing an environment (4) of the motor vehicle (1) in a computing device (6) of the driver assistance system (2), a) detecting a movement of the motor vehicle (1) relative to its surroundings (4) by a sensor device (3) of the driver assistance system (2), c) moving a vehicle model (8) of the motor vehicle (1) on the map (7) in dependence on the detected movement by the computing device (6), wherein the vehicle model (8) on the map (7) in dependence of a rotation of the motor vehicle (1) about a vehicle vertical axis transverse to a vehicle longitudinal axis (L) of the vehicle model ( 8) along a circular arc of a circle (10, 10 ') with a predetermined radius (r, r') is moved to the map (7) of the environment (4) of the motor vehicle (1) in the driver assistance system (2) and available at low computational cost too put.

Description

The invention relates to a method for operating a driver assistance system of a motor vehicle, with method steps a) providing a map, which represents an environment of the motor vehicle, in a computing device of the driver assistance system, b) detecting a movement of the motor vehicle relative to its surroundings by a sensor device of the driver assistance system and c) moving a vehicle model of the motor vehicle on the map as a function of the detected movement by the computing device.

In driver assistance systems of motor vehicles, essentially two different types of cards are used today. First, these are the global raster maps, the so-called Global Grid Maps. These require a large memory, for example, four megabytes, and bind many computational resources when they are accessed or, if necessary, perform a transformation such as a shift or rotation of the card. At the same time, even with very large maps, it can never be completely ruled out that a vehicle moves out of a map boundary, with the result that the map has to be recalculated.

On the other hand, the local grid maps (Local Grid Maps) are used. Here, on the one hand, a distinction is made between maps in which the position of a vehicle model on the map, for example in a center of the map, is fixed, and other implementations in which the vehicle moves freely on the map. In the former case, a computation-intensive shift and possibly also rotation of the card is required at each update step, that is, at each movement of the motor vehicle. At the same time, displacements and rotations of the card due to the quantized grid cells with a given grid size of, for example, ten to twenty centimeters, in which a grid cell corresponds to, for example, a square with ten to twenty centimeters edge length, cause inaccuracies in the map, for example when in a so-called subpixel image Shifting, a shift of the card by an amount which is smaller than the grid size, and when rotating the map respectively approximations and interpolations must be estimated.

Moreover, the card contains basically the same amount of information regardless of a direction of movement of the motor vehicle in all vehicle directions. This is not advantageous for a driver assistance system since, for example, for a motor vehicle traveling at high speed, the information on the map before the corresponding vehicle model is more valuable than information behind the vehicle model. Anisotropic map approaches that provide more space on the map in one or more preferred vehicle directions require computationally-intensive mapping operations.

In the case of a vehicle model that is freely movable on the map, the amount of information that can be used by a driver assistance system depends on the particular route selected, which in turn is unfavorable for the use of the map in the driver assistance system. Also, the vehicle model often overrides the card limits, so leave the card frequently, which means that the card must be recalculated frequently.

The present invention has for its object to provide in a driver assistance system of a motor vehicle, a map of the environment of the motor vehicle accurately and with little computational effort available.

This object is solved by the independent claims. Advantageous embodiments will become apparent from the dependent claims, the description and the figures.

The invention relates to a method for operating a driver assistance system of a motor vehicle, with a series of method steps. A first method step here is to provide a map, which represents an environment of the motor vehicle, in a computing device of the driver assistance system. The card may include, for example, high-resolution map material. Map information of a navigation system and / or one or more sensor devices can be provided in the map. Map information from several different sources can thus be combined in the map. A further method step is a detection of a movement of the motor vehicle relative to its or the surroundings by a sensor device of the driver assistance system. The detection of the movement of the motor vehicle can take place via various vehicle sensors in order to obtain information about the movement of the motor vehicle. In this case, a rotation or yaw of the motor vehicle and braking, for example, by an electronic stability control program (ESP) can be determined. One Steering angle can be detected accordingly by a steering angle sensor and a speed of the motor vehicle by a sensor in the drive train, such as a transmission control unit (Transmission Control Unit). A next method step is a movement of a vehicle model of the motor vehicle on the map as a function of the detected movement by the computing device. The vehicle model is thus a representation of the motor vehicle on the map.

In the present case, the vehicle model on the map is moved around a vehicle vertical axis of the motor vehicle relative to its surroundings, ie yawing of the motor vehicle, transversely to a vehicle longitudinal axis of the vehicle model along a circular arc of a circle with a predetermined or predeterminable radius , The vehicle model is thus always arranged with the longitudinal axis radially to the circle and is moved in a yaw of the motor vehicle on the circular arc. The vehicle transverse axis of the vehicle model runs parallel to a tangent of the circular arc. The vehicle model is thereby displaced on the circular arc transversely to the vehicle longitudinal axis of the vehicle model by an angle which depends on the yaw angle of the motor vehicle. A circular arc of a circle with a given radius can here also be understood to mean a corner-free path arc, so that a predetermined deviation from a mathematically exact circular arc can also be understood as a circular arc. Specifically, when moving along the arc of the circle, the vehicle model may be moved from the circle and the given radius with a deviation smaller than a raster size of the map. Preferably, the radius is different from zero.

This has the advantage that a rotation of the card is avoided by the method described, since it is the vehicle model that rotates on the map. This avoids smearing of the card due to the approximations or interpolations that would otherwise be required during a rotation of the card, which occur precisely in the case of slight rotations. At the same time, the computationally complicated rotation of the card, in which new positions have to be calculated or estimated for all objects on the card, is avoided. At the same time it is thus possible to use a smaller card and thus to save memory, since the arrangement on the circle always automatically covers a large part of the map in the longitudinal direction of the vehicle model and thus each relevant to the driver assistance system information about the environment Motor vehicle represents. By the appropriate choice of the circle and the circle center on the map is thereby reliably prevented that the vehicle model on the arc leaves the map or exceeds a map limit.

This eliminates the otherwise possibly to be performed complete reload of the card. Thus, instead of the complete map with all the objects on the map, only the vehicle model is rotated. Since much more precise information is available on this than about the environment of the motor vehicle, there is no loss of accuracy here even with small movements of the vehicle model on the map. Moreover, in the described and all following embodiments, the method is compatible with quadtree compression of the card, so that the method can be applied to a card compressed by quaternary tree compression and resources can be saved again.

In an advantageous embodiment, it is provided that the card comprises or is a raster map, a so-called grid map. In particular, the card may include or be an occupancy map. The resolution of a raster map is determined by its grid size. The grid size can denote the value corresponding to a respective edge length of the grid cell in the real world. Thus, for example, the raster map have a grid size of ten centimeters, that is a grid cell corresponding to an area of the environment with a size, for example, length and width of ten centimeters. The grid size can thus correspond to the resolution of the map. The occupancy grid map can also be referred to as an occupancy map. In this case, a value is provided for each grid cell, for example between zero and one, where, for example, zero represents a free area in the surroundings of the motor vehicle and one represents an occupied area. Intermediate values can also be provided here in order to reflect an occupancy probability.

This has the advantage that especially in the case of a raster or occupancy grid map, the advantages described come into their own and, moreover, an occupancy grid map is particularly suitable for representing an environment of the motor vehicle for a driver assistance system.

In a further advantageous embodiment, it is provided that the angle of movement of the vehicle model along the circular arc, the rotation angle of the vehicle model, equal to the angle of rotation, ie the yaw angle of the motor vehicle. Thus, the vehicle turns once in a circle in his Origin orientation back, so also applies to the vehicle model. The angle of rotation of the vehicle model about the center of the circle is thus equal to the yaw angle of the motor vehicle during a rotation or a yaw of the motor vehicle.

This has the advantage that on the one hand a complicated conversion of a rotation or the yaw angle can be translated into a rotation angle on the map. Moreover, so the card must not be rotated at all, to accurately and reliably map the motor vehicle in its relation to the environment.

In a further advantageous embodiment, it is provided that the vehicle model is radially oriented with its vehicle model front to the center of the circle during a forward driving of the motor vehicle in the vehicle longitudinal axis, and when reversing the motor vehicle in the vehicle longitudinal axis viewed radially with his vehicle model back to Center of the circle is oriented. In both cases, as already described above, so the vehicle longitudinal axis of the vehicle model is arranged radially to the center of the circle.

This has the advantage that always a large part, for example, the majority of the map, in the current direction of travel of the motor vehicle and thus the vehicle model in front of the vehicle model is arranged, and thus in the map to a large extent or even the majority for the driver assistance system Relevant information, namely located in the current direction in front of the vehicle model information stored. As a result, overall smaller cards can be used and memory of the computing device can be saved. As a result, in principle and mathematically, the region of the surroundings in the current direction of travel in front of the vehicle is always automatically represented, which is particularly important for the driver assistance system and thus for controlling the motor vehicle. Thus, the map is automatically adapted to the typical scenarios. A separate computation-intensive calculation, as is known, for example, from anisotropic maps, is not required.

In a further advantageous embodiment, it is provided that the radius of the circle is predetermined as a function of a driving speed of the motor vehicle. In particular, this can essentially be predetermined by the driving speed. Essentially, this is to be understood as predetermining the radius in integer multiples of the grid size, that is, down to a modulo of the grid size. For example, such a radius at a grid size of ten centimeters can be set to plus-minus five centimeters.

This has the advantage that the driving speed of the motor vehicle can be taken into account in the map display, and thus a particularly flexible map with a high information density is provided. This map is very accurate and the adaptation to the driving speed is done only via an adjustment of a single parameter, namely the radius, without binding any significant capacity of the computing device.

In a particularly advantageous embodiment, it is provided that a larger radius is specified for a greater driving speed than for a lower driving speed. Thus, for example, in a highway driving at high speed, a large radius can be set, and in a city driving at a low speed, in which frequent changes of direction is to be expected, a small radius.

This has the advantage that the part of the map, which is for the driver assistance system in all probability particularly important, namely the part (in the direction of travel) in front of the vehicle model occupies a correspondingly large part of the map. Thus, for example, a change of direction is not to be expected during a motorway journey, so that above all the area in front of the motor vehicle and thus in front of the vehicle model is interesting for the driver assistance system. In a city, however, with frequent changes of direction and many other road users, a lateral or rearward area of the motor vehicle may be more important compared to the front area than on a highway. Moreover, due to the lower speed, a less large area must be considered by the driver assistance system than at a high speed in front of the motor vehicle. Here, too, an automatic adaptation of the area of the environment represented in the map to a corresponding importance for the driver assistance system takes place with a low computational effort.

mit ${\displaystyle {\sum }_{k=1}^n{a}_k=1}$

dargestellt werden, wobei die jeweilige Fahrgeschwindigkeit S zu dem Zeitpunkt t durch die Veränderung der Position, also beispielsweise der x und y Koordinaten des Fahrzeugs in der Realwelt errechnet wird. In a further advantageous embodiment, it is provided that the driving speed via a comparison of the position of the motor vehicle at different times or iterations is calculated. In particular, the calculated driving speed can be smoothed with the aid of a low-pass filter. For example, a smoothed vehicle speed Ŝ _t at a time t via the formula ${\widehat{\text{S}}}_t={\displaystyle {\Sigma }_{k=1}^n{a}_k*S_{t-k+\mathrm{1,}}}$

With ${\displaystyle {\Sigma }_{k=1}^n{a}_k=1}$

are represented, wherein the respective driving speed S at the time t by the change of position, so for example the x and y coordinates of the vehicle is calculated in the real world.

For example, for the smoothed vehicle speed Ŝ _{t to be} the mean of the speed S at time t and the n-1 advancing speeds, a _k = n ^{-1 can be} assumed. As soon as the speed Ŝ _{t takes} a negative value, the vehicle moves backwards. Of course, other low-pass filters can be used.

This has the advantage that any jumps, as they are known in the velocity calculation and position calculation from the isometry due to sensor noise or sensor jitter, are smoothed, and thus the accuracy of the card is increased or maintained with little effort.

In an advantageous embodiment, it is provided that the center of the circle lies in a center of the map. In this case, the position of the center of the circle essentially, that is, to an accuracy which is determined by the grid size of the map, for example, be limited to modulo the grid size.

This has the advantage of ensuring that, even with a variable radius, a large part of the map always represents the information about the environment which is important for the driver assistance system.

In a further advantageous embodiment it is provided that a map information, for example an occupancy information of a raster cell, depending on a translation of the motor vehicle, which may for example be relative to the environment of the motor vehicle, on the card, for example in an x and / or y -Direction, which is only shifted by integer multiples of a grid size of the map. Thus, for example, in a translation of the motor vehicle by a distance which does not correspond to an integer multiple of the grid size of the card, the non-integer remainder of the shift is ignored. For example, in the case of a translation of the motor vehicle by 23 centimeters, map information can be shifted on the map at a grid size of ten centimeters by two grid cells, ie 20 centimeters in the real environment. The shift is thus modulo the grid size. The shifting of the map information described in this paragraph can also be realized independently of the arrangement and movement of the vehicle model on the circle or arc. The embodiment described in this paragraph can therefore also be considered as an independent aspect of the invention.

The integer shifting can be achieved, for example, by describing an occupancy map M ^t at time t, here given in the form of a matrix M with corresponding entries between zero and one, in response to a displacement P _{shift of} the vehicle model with the equation $$M^t={\left(U_w\right)}^{\left[P_{sHift}^x\right]}*{\left\{{\left({\left(L_H\right)}^{\left[P_{sHift}^y\right]}*M^{t-1}\right)}^T\right\}}^T\text{,}$$

in x-Richtung beziehungsweise der Verschiebung $P_{shift}^y$

in y-Richtung und L_H und U_w jeweilige Verschiebungsmatrixen, wobei H und W die Höhe und Weite der Karte M^t in Anzahlen der Pixel, also die Anzahl der Zeilen und Spalten der Matrix M ist. Dabei verschiebt die Gleichung die Karte M^t entsprechend dem ganzzahligen Teil von $P_{shift}^x$

und $P_{shift}^y$

nach links beziehungsweise nach unten. P_shift ist dabei gegeben durch: $$P_{shift}=P_{world}^t-P_{world}^{t-1}+P_{local}^{t-1}-P_{circle}^t\text{.}$$

wobei $P_{world}^t$

eine Odometrieinformation über die Position des Kraftfahrzeugs zum Zeitpunkt t in einem Bezugssystem der Umgebung des Kraftfahrzeugs (in „Weltkoordinaten“) ist, $P_{circle}^t$

eine Position des Kreises repräsentiert, und über $P_{local}^{t-1}$

eine anfängliche Verschiebung, ein sogenannter „Offset“, des Fahrzeugmodells auf der Karte berücksichtigt wird. Dabei kann für t=0 als Anfangsbelegung $P_{local}^0=P_{circle}^1$

und $P_{world}^0=P_{world}^1$

angenommen werden, also dass sich anfangs das Fahrzeugmodell im Kreismittelpunkt befindet und das Kraftfahrzeug steht.Here, the square brackets denote each integer part of the shift $P_{sHift}^x$

in the x-direction or the displacement $P_{sHift}^y$

in the y-direction and L _H and U _w respective displacement matrices, where H and W is the height and width of the map M ^t in numbers of pixels, that is the number of rows and columns of the matrix M. At this time, the equation shifts the map M ^t corresponding to the integer part of $P_{sHift}^x$

and $P_{sHift}^y$

to the left or down. P _shift is given by: $$P_{sHift}=P_{wOrld}^t-P_{wOrld}^{t-1}+P_{lOcal}^{t-1}-P_{circle}^t\text{,}$$

in which $P_{wOrld}^t$

is odometry information about the position of the motor vehicle at time t in a frame of reference of the environment of the motor vehicle (in "world coordinates"), $P_{circle}^t$

represents a position of the circle, and about $P_{lOcal}^{t-1}$

an initial shift, a so-called "offset", of the vehicle model on the map is taken into account. Here, for t = 0 as the initial assignment $P_{lOca\mathrm{<figure-callout\; id="0"\; label="l"\; filenames="DE102016122031A1\_0017.png,DE102016122031A1\_0018.png"\; state="\{\{state\}\}">l</figure-callout>}}^0=P_{circle}^1$

and $P_{wO\mathrm{<figure-callout\; id="0"\; label="r\; l\; d"\; filenames="DE102016122031A1\_0017.png,DE102016122031A1\_0018.png"\; state="\{\{state\}\}">r\; </figure-callout>}ld}^0=P_{wO\mathrm{<figure-callout\; id="1"\; label="r\; l\; d"\; filenames="DE102016122031A1\_0015.png,DE102016122031A1\_0017.png"\; state="\{\{state\}\}">r\; </figure-callout>}ld}^1$

be assumed, so that initially the vehicle model is located in the center of the circle and the motor vehicle is.

This has the advantage that an interpolation or an approximation or estimation of the map information, as it necessarily occurs during a shift in the sub-grid cell area, is avoided, so that a corresponding smearing of the map is omitted and this is still available in a maximum accuracy. At the same time, the computation-intensive interpolation, which would be required correspondingly for each card information or for each card pixel or card cell, can be omitted.

In a further particularly advantageous embodiment, provision is made for the vehicle model to be a residual value as a function of the (or a) translation of the motor vehicle, for example of the motor vehicle relative to the surroundings, on the map, for example in an x and / or y direction is shifted from the (or an integer multiple of the (or a) grid size of the map. The residual value can also be modulo the raster size of the map here. The residual value is therefore always smaller than the grid size. For example, in the above example of a movement of the motor vehicle by 23 centimeters, the vehicle model on the map would be shifted according to the equivalent of 23 modulo grid size, ie 23 modulo 10 = 3 centimeters. In particular, it may be provided that the vehicle model is displaced depending on the translation of the motor vehicle on the map only by the respective residual value. In addition, in this case, only a displacement or a movement of the vehicle model, depending on the above-described rotation, the yaw, of the motor vehicle would come. The displacement of the vehicle model described in this paragraph can also be realized independently of the arrangement and movement of the vehicle model on the circle or arc, for example, in cooperation with the above described moving the map information. The embodiment described in this paragraph can therefore also be considered as an independent aspect of the invention.

This has the advantage that the vehicle model can be positioned very accurately on the map. Especially along with the last described embodiment, on the one hand, the accuracy of the card is maintained with little computational effort and at the same time achieves an accurate positioning of the vehicle model relative to any objects on the map with as little computational effort. In this case, the computational effort which is required when moving the map by non-integer multiples of the grid size is also saved, although even better accuracy is achieved than in the so-called subpixel shifting.

wobei die geschweiften Klammern hier den nicht-ganzzahligen Restwert der Verschiebung P_shift bezeichnen. Beispielsweise kann gelten {P_shift} = P_shift modulo (Rastergröße). So würde beispielsweise in dem genannten Beispiel entweder der Radius um drei Zentimeter erhöht oder aber der Mittelpunkt des Kreises entsprechend entgegen der Bewegung der Translation des Kraftfahrzeugs um drei Zentimeter verschoben.The shifting of the vehicle model by the residual value can be realized, for example, by adding the corresponding residual value on the radius of the circle and / or shifting the center of the circle according to the translation. The displacement of the vehicle on the map with the non-integer part of the displacement can be described by, for example $$P_{lOcal}^t=P_{circle}^t+\left\{P_{sHift}\right\}\text{.}$$

where the curly braces here denote the non-integer residual value of the shift P _shift . For example, {P _shift } = P _shift modulo. For example, in the example mentioned, either the radius would be increased by three centimeters, or the center of the circle would be displaced by three centimeters corresponding to the movement of the translation of the motor vehicle.

In a particularly preferred embodiment, it is provided that the method steps b) and c), ie the detection of the movement of the motor vehicle and the movement of the vehicle model the card depending on the detected movement, repeated, in particular continuously performed. The method can thus be implemented as an iterative method.

This has the advantage that a current map can always be used for the driver assistance system. Since the position of the motor vehicle on the circle and possibly the radius of the circle are recalculated for each time step here, there is no risk that the vehicle model leaves the map. Therefore, the method described is particularly suitable for the driver assistance system and places low demands on the computing capacity.

In a further advantageous embodiment, provision is made for at least one subregion of the card to be provided by the computing device. For example, the at least one subarea of the map can thereby be provided to a further device of the driver assistance system, for example a display device of the driver assistance system, in order to display the at least one subarea of the map, for example to display a driver. In this case, a partial area of the card which lies within the circle is provided with a greater resolution than a partial area of the card which lies outside the circle. Thus, depending on the driving situation, certain sections of the map, namely the Teilbeireche inside the circle and thus of particular relevance to the driver assistance system can be loaded with higher resolution. For example, when driving slowly in a city, only a relatively small section of the map is needed, which can then be provided with high resolution. For example, the close vicinity of the motor vehicle can thus be provided or displayed with double resolution, without, however, increasing the memory requirements, for example, in the further device. Even with a slow reversing the environment behind the motor vehicle can thus be provided in a higher resolution. On a motorway, however, a larger area of the map is needed, thus, for example, the resolution within the circle compared to driving in the city at a lower resolution provided or displayed.

An important aspect of the invention can thus be seen in representing the vehicle model in the map on a circle. In this case, the vehicle model is arranged orthogonal to the tangent of the circle and preferably aligned with in its direction of movement always to the center of the circle. The center of the circle can be the center of the map. The radius of the circle and the exact position of the vehicle model on the circle can be dependent on the odometry data. The faster the vehicle drives, the larger the radius of the circle can be. The change in the yaw angle of the motor vehicle determines the change in the position of the vehicle model on the circle.

The invention also relates to a driver assistance system of a motor vehicle, having a sensor device for detecting a movement of the motor vehicle relative to its surroundings and having a computing device in which a map representing the surroundings of the motor vehicle is provided and which is formed on the map in FIG Dependence of the detected movement to move a vehicle model of the motor vehicle. It is important that the computing device is designed to move the vehicle model on the map in response to a rotation or yawing of the motor vehicle about the vehicle vertical axis transverse to a vehicle longitudinal axis of the vehicle model along a circular arc of a circle with a predetermined radius.

Advantages and advantageous embodiments of the driver assistance system correspond to advantages and advantageous embodiments of the method described for operating such a driver assistance system.

The invention also relates to a driver assistance system which is designed to carry out a method according to the invention or an advantageous embodiment of the method according to the invention.

The invention also includes a motor vehicle with such a driver assistance system.

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 in the figures alone can be used not only in the respectively indicated combination but also in other combinations or in isolation, without the scope of To leave invention. Thus, embodiments are also included and disclosed by the invention, which are not explicitly shown or explained in the figures, but by separated feature combinations from the explained embodiments emerge and are producible. Thus, embodiments and combinations of features are also to be regarded as disclosed which do not have all the features of an originally formulated independent claim.

Moreover, embodiments and combinations of features, in particular by the embodiments set out above, are to be regarded as disclosed, which go beyond or deviate from the combinations of features set out in the back references of the claims.

Embodiments of the invention are explained in more detail below with reference to schematic drawings.

• 1 eine schematische Ansicht eines Kraftfahrzeug mit einer beispielhaften Ausführungsform eines Fahrerassistenzsystems;
• 2 eine Skizze einer Karte mit Fahrzeugmodellen in mehreren beispielhaften Positionen;
• 3 eine Darstellung einer beispielhaften Ausführungsform einer Karte in einem ersten Szenario;
• 4 die beispielhafte Ausführungsform einer Karte von 2 in einem weiteren beispielhaften Szenario;
• 5 eine beispielhafte Darstellung einer Karte für eine Serie von Iterationsschritten; und
• 6 die jeweilige Geschwindigkeit des Kraftfahrzeugs für das Beispiel aus 4 in der Serie von Iterationsschritten.

Showing:

• 1 a schematic view of a motor vehicle with an exemplary embodiment of a driver assistance system;
• 2 a sketch of a map with vehicle models in several exemplary positions;
• 3 a representation of an exemplary embodiment of a card in a first scenario;
• 4 the exemplary embodiment of a map of 2 in another exemplary scenario;
• 5 an exemplary representation of a map for a series of iteration steps; and
• 6 the respective speed of the motor vehicle for the example 4 in the series of iteration steps.

The same or functionally identical elements are provided in the various figures with the same reference numerals.

1 shows a motor vehicle 1 with an exemplary embodiment of a driver assistance system 2 schematically from a bird's eye view. The driver assistance system 2 in the present case comprises a sensor device 3 for detecting a movement of the motor vehicle 1 relative to an environment 4 of the motor vehicle 1 , ie a movement of the motor vehicle 1 relative to its environment 4. In the present case, this sensor device 3 as a camera system with here four cameras 5a-d running. The driver assistance system 2 in the present case also includes a computing device 6 in which a card 7 which the environment 4 of the motor vehicle 1 is provided. The computing device 6 is trained on the map 7 depending on the detected movement of the motor vehicle 1 a vehicle model 8th of the motor vehicle 1 to move.

Here is the computing device 6 trained, the vehicle model 8th on the map in response to a rotation of the motor vehicle 1 about a vehicle vertical axis of the motor vehicle 1 transverse to a vehicle longitudinal axis L ( 2 ) of the vehicle model 8th along a circular arc of a circle 10 . 10 ' ( 2 ) with a given radius r, r '( 2 ) to move.

In the present case includes the driver assistance system 2 also a display device 9 on which the vehicle model 8th and the card 7 is shown.

In 2 is a schematic diagram of an exemplary map 7 with a vehicle model 8th presented in several different positions ad. In the real application will appear in the map 7 the vehicle model 8th Of course, at one time only be shown in one of the positions ad. At the card 7 In the present case, this is a so-called occupancy map, a local occupancy map. It is in the example shown for reasons of clarity, the grid 11 ( 5 ) the map 7 not shown.

The vehicle model 8th is in the respective positions ad thereby each oriented with its vehicle longitudinal axis L to a center M of two concentric rings or circles 10a, 10b out. The center M can be present in a center of the map 7 be positioned. The present is the card 7 square, which is particularly advantageous. The orientation of the vehicle model 8th corresponds in each case to a predetermined orientation of the motor vehicle 1 ( 1 ) in the neighborhood 4 ( 1 ). Now changes the orientation of the motor vehicle 1 relative to its surroundings 4 in that the motor vehicle 1 rotates about its vehicle vertical axis, that is, yawing of the motor vehicle 1 takes place, then the orientation of the vehicle model 8th in the map 7 to the new orientation of the motor vehicle 1 adapted by the vehicle model 8th on the circle 10a . 10b along the respective circular arc transverse to the vehicle longitudinal axis L of the vehicle model 8th is moved.

For example, a vehicle model 8th present at a yaw of the motor vehicle 1 by a yaw angle along the arc of the first circle 10 moved from the first position a by a corresponding rotation angle α in the second position b. In particular, the angle of rotation α may be equal to the yaw angle of the motor vehicle 1 be. The radius r, r 'of the two circles 10 . 10 ' according to the speed of the motor vehicle 1 specified. For a larger speed, the radius r, r 'is presently greater than for a smaller speed. In the example shown, the displacement of the vehicle model 8th from the first position a to the second position b, a speed of the motor vehicle thus remains in the present case 1 in the same yaw, as the vehicle model 8th in the second position b still on the first circle 10 with the given radius r. When moving on the circle 10 The vehicle longitudinal axis L always remains radial to the circle 10 , 10 'oriented. A vehicle transverse axis of the vehicle model 8th thus always runs tangentially or parallel to a tangent of the circles 10 . 10 ' along which the vehicle model 8th at a yaw of the motor vehicle 1 moved or moved.

In the third position c is the vehicle model 8th now shown in the same orientation as in the first position a, but now it is on the second circle 10 ' with the second radius r '. Starting from the first position a has the motor vehicle 1 , which by the vehicle model 8th in the map 7 is represented, so in this case its orientation relative to the environment 4 , not changed, but its speed is reduced. Accordingly, the second radius r 'is smaller than the first radius r'. For example, the radius r, r 'of the respective circle 10 . 10 ' on which the vehicle model 8th during a rotation of the motor vehicle 1 is moved, proportional to a driving speed of the motor vehicle 1 be.

In the first three positions a, b, c, the motor vehicle moves 1 in this case forward. Correspondingly, in each of these three positions ac, the front sides of the vehicle model are shown 8th to the center M of the circles 10 . 10 ' out. This represents a large part of the map 7 namely the area of the map 7 which is within the respective circle 10 . 10 ' located, an area of the environment 4 in a direction of travel in front of the motor vehicle 1 , That's exactly the area of the environment 4 , which during a forward drive for the operation of the driver assistance system 2 ( 1 ) is particularly important.

Now drives the vehicle 1 backwards, the described orientation no longer makes sense. Accordingly, when reversing on the map 7 the vehicle model 8 also with its vehicle longitudinal axis L radially to the respective circles 10 . 10 ' arranged, however, with its rear side to the center M of the circles 10 . 10 ' pointing out. This also serves a large part of the map when reversing 7 the representation of a in the direction of travel of the motor vehicle 1 located area of the environment 4 , On the one hand, this always ensures the correct orientation of the vehicle model 8th on the map 7 ensured, while ensuring that a large part of the card 7 for the driver assistance system 2 ( 1 ) actually interesting area of the environment 4 namely the area of the environment 4 , which in a current direction of travel of the motor vehicle 1 lies, pictures. This can be a rotation of the card 7 , which is computationally expensive and leads to blurring and inaccuracies, stay away.

To a translation of the motor vehicle 1 on the map 7 also to be considered, can now be provided advantageously, a map information on the map 7 For example, an occupancy information about a grid cell of the card 7 to move to the map 7. In the prior art, such a displacement, which is correspondingly proportional to a translational movement of the motor vehicle 1 in the neighborhood 4 takes place, basically known. In the present case, however, such shifting only takes place by an integer multiple of a grid size of the card 7 instead of. Accordingly, so when moving the motor vehicle 1 in one direction, which is the y-direction of the map 7 corresponds to the map information on the map 7 shifted in negative y-direction. In this case, for example, at the upper end of the card in the positive y-direction 7 a new line is inserted in the occupancy map and a corresponding line in the lower y direction of the lower end of the map 7 to be deleted. Mutatis mutandis applies to moving the motor vehicle in one on the map 7 the negative y-direction or the positive and / or negative x-direction corresponding direction.

Due to the fact that the corresponding shift in the present case always takes place only by an integer multiple of the grid size, the corresponding rows or columns of the card become 7 Here only one row or column shifted, so that with the avoided sub-pixel shifting, the avoided shifting by non-integer multiples of a grid size of the map 7 , also time-consuming and the inaccuracy of the card 7 avoiding interpolations and estimates. Nevertheless, the position of the vehicle model 8th relative to a map information of the card 7 more accurate than up to a multiple of the grid size of the card 7 to be able to play, can be provided here, the vehicle model 8th depending on the translation of the motor vehicle 1 on the map 7 to the respective residual value of the integer multiple of the grid size of the map 7 to move.

A translational movement of the motor vehicle 1 can thus be divided into a first value, which on the map 7 by moving the map information on the map 7 is taken into account and which in each case an integer multiple of the grid size of the map 7 corresponds, and in a second value, which on the map by moving the vehicle model 8th is taken into account and which in each case corresponds to the remainder of the integer multiple, ie an amount of the translation modulo the grid size. The shift of the vehicle model 8th can be realized, for example, by the center M of the circles 10 . 10 ' is shifted by the corresponding residual value in the y- or x-direction, or the radius r, r 'is adjusted according to the residual value. As the vehicle model 8th basically available in more accurate resolution than the map information, the vehicle model can 8th also on the map 7 be moved accordingly fine, without resulting in an inaccuracy. Because only the vehicle model 8th To shift the corresponding residual value, the move is also associated with very little computational effort.

In 3 is an exemplary card 7 presented in a first scenario. Here again is the grid of the map 7 not shown, but it has 300 times 300 grid or grid cells. In the example shown, the motor vehicle moves 1 at a speed of around 15 km / h through a given urban area. The radius of the circle is corresponding 10 along which the vehicle model 8th Moving in a rotation is compared to a greater speed, as in 4 shown is smaller than there. This will be in the card 7 automatically represents the area potentially for the driver assistance system 2 of the motor vehicle 1 is of interest. Thus, especially in an urban environment, especially at low speeds, for example, a change of direction is more likely, so possibly also an environment 4 behind the motor vehicle 1 for the driver assistance system 2 may be significant. Also, at low speeds, the driver assistance system 2 for safe operation in the direction of travel of the motor vehicle 1 Less far to the front must be able to see what is achieved here automatically.

In 4 is the card 7 out 3 shown in another example scenario. In the present case, the motor vehicle is moving 1 with a higher speed of about 70 km / h on a highway. Accordingly, the radius r is larger in the present case, so that a larger part than in the in 3 shown example of the map 7 the environment 4 in the direction of travel in front of the motor vehicle 1 represents. Since at a high speed, a change of direction is less likely and the environment 4 behind the motor vehicle 1 and thus behind the vehicle model 8th is of lesser importance, here is also unproblematic that the vehicle model 8th at a larger radius r closer to a limit of the map 7 is located and thus the environment 4 of the motor vehicle 1 behind in the direction of travel this on the map 7 optionally not represented.

In 5 is an exemplary course of the position and orientation of the vehicle model 8 on the map 7 represented for a series of time steps i. In the example shown, the detection of the movement of the motor vehicle 1 and moving the vehicle model 8th of the motor vehicle 1 on the map 7 while iteratively carried out continuously. For illustration are here in the map 7 for 40 iteration or time steps i the respective positions and orientations of the vehicle model 8th in the map 7 as well as the respective circles 10 drawn for the time steps i. The circles belonging to a respective time step i 10 are denoted by "10 (i = 1-40)". In the example shown makes the motor vehicle 1 a left turn 270 degrees, wherein in the course of the left turn the speed of the motor vehicle 1 , as in 6 shown, drops.

The vehicle model 8th is on the map 7 initially pointing with its longitudinal axis L in the direction of positive x-direction and initially, since the driving speed of the motor vehicle 1 here at the beginning is highest, on the outermost circle 10 (i = 1) arranged with the largest radius r. For the next iteration step i = 2, the vehicle model moves 8th here counterclockwise along the circle 10 (i = 2), whose radius r is present, as out 6 apparent, almost identical to the radius r of the first circle 10 (i = 1) is further, giving the new orientation of the vehicle model 8th in time step i = 2 again the orientation of the motor vehicle 1 in the neighborhood 4 equivalent. This initially continues for the further iteration steps. In 5 Also shown is an enlarged map detail in which the orientations of the vehicle longitudinal axis L and the position of the vehicle model 8th for the time steps i = 2 to i = 7 are shown.

Here are the vehicle models 8th not exactly on the respective circles 10 positioned, for example, is the vehicle model 8th for the time step i = 3 even outside of the largest circle 10 (i = 0). This is present by the translational movement of the motor vehicle 1 conditionally, which in the example shown, as described for the previous embodiment, to a shifting of the map information by integer multiples of the grid size R, so that corresponding shares of the translation of the motor vehicle 1 , which can not be considered by a shift of the map information by the integer multiples of the grid size R, in this case by a corresponding displacement of the vehicle model 8th on the map 7 be compensated. This manifests itself in corresponding jumps of the vehicle model 8th on the map 7 in the x or the y direction, which, for example, to the positioning of the vehicle model 8th outside the circle 10 (i = 0) for the time step i = 3.

In the course of the 270 degrees left turn of the motor vehicle 1 Thus, the longitudinal direction L of the vehicle model rotates 8th from a transverse orientation in the positive x-direction over a high orientation in the positive y-direction and a transverse orientation in the negative x-direction towards a high orientation in the negative y-direction for the last iteration step i = 40. Because at the same time the speed of the motor vehicle 1 decreases, the displacement of the vehicle model takes place 8th along the circular arc of the circle 10 with decreasing radius r. This circle 10 is drawn here for the different time steps and thus leads to a spiral movement of the vehicle model 8 on the map 7 to the center of the circle 10 ,

The map 7 is present as occupancy grid map with a grid 11 executed, which a variety of grid cells 12 having. The grid cells 12 are here as well as the card 7 square and have an edge length, which is called grid size R of the map 7 is designated. The grid size R can be, for example, 10 centimeters.

In 6 is the speed of the motor vehicle 1 in km / h over the number of iteration steps i. The speed of the motor vehicle for the first iteration step i = 0 is 90 km / h and drops exponentially to 20 km / h for the 40th iteration step i = 40 in the present case. From this waste can be the distance of the individual circles 10 (i = 0-40) for the individual iteration steps i. In the present case, the radius r was determined to be proportional to the speed for the respective iteration step i.

Claims (14)

Method for operating a driver assistance system (2) of a motor vehicle (1), with the method steps: a) providing a map (7) representing an environment (4) of the motor vehicle (1) in a computing device (6) of the driver assistance system (2 ); b) detecting a movement of the motor vehicle (1) relative to its surroundings (4) by a sensor device (3) of the driver assistance system (2); c) moving a vehicle model (8) of the motor vehicle (1) on the map (7) as a function of the detected movement by the computing device (6), characterized in that the vehicle model (8) on the map (7) in response to a rotation of the motor vehicle (1) about a vehicle vertical axis transverse to a vehicle longitudinal axis (L) of the vehicle model (8) along a circular arc of a circle (10, 10 ') with a predetermined radius (r, r') is moved. Method according to Claim 1 , characterized in that the card (7) comprises a raster map, in particular a occupancy grid map. Method according to one of the preceding claims, characterized in that the angle (α) of the movement of the vehicle model (8) along the circular arc is equal to the angle of rotation of the motor vehicle (1). Method according to one of the preceding claims, characterized in that the vehicle model (8) is oriented in a forward driving of the motor vehicle (1) with its vehicle model front to the center (M) of the circle (10, 10 ') out, and in a reverse drive of the motor vehicle (1) with its vehicle model Heck to the center (M) of the circle (10, 10 ') is oriented towards. Method according to one of the preceding claims, characterized in that the radius (r, r ') of the circle (10, 10') is predetermined as a function of a driving speed of the motor vehicle (1). Method according to Claim 5 , characterized in that for a greater driving speed, a larger radius (r, r ') is specified as for a lower driving speed. Method according to one of Claims 5 to 6 , characterized in that the driving speed is calculated by comparing the position of the motor vehicle (1) at different times, wherein in particular the calculated driving speed is smoothed by means of a low-pass filter. Method according to one of the preceding claims, characterized in that the midpoint (M) of the circle (10, 10 ') lies in a center of the card (7). Method according to one of the preceding claims, characterized in that a map information in response to a translation of the motor vehicle (1) on the card (7) only by integer multiples of a grid size (R) of the card (7) is moved. Method according to one of the preceding claims, characterized in that the vehicle model (8) as a function of the translation of the motor vehicle (1) on the card (7) by a residual value of the integer multiple of the grid size (R) of the card (7) is moved , Method according to one of the preceding claims, characterized in that the method steps b) and c) are carried out repeatedly, in particular continuously. Method according to one of the preceding claims, characterized by providing at least a portion of the card (7) by the computing device (6), in which a portion of the card (7) which lies within the circle (10, 10 ') with a greater resolution is provided as a portion of the card (7) which lies outside the circle (10, 10 '). Driver assistance system (2) of a motor vehicle (1), having - a sensor device (3) for detecting a movement of the motor vehicle (1) relative to its surroundings (4); - A computing device (6) in which a card (7), which represents the environment (4) of the motor vehicle (1) is provided, and which is formed on the card (7) in dependence of the detected movement, a vehicle model ( 8) of the motor vehicle (1) to move; characterized in that the computing device (6) is formed, the vehicle model (8) on the map (7) in response to rotation of the motor vehicle (1) about a vehicle vertical axis transverse to a vehicle longitudinal axis (L) of the vehicle model (8 ) along a circular arc of a circle (10, 10 ') with a given radius (r, r') to move. Motor vehicle (1) with a driver assistance system (2) according to Claim 12 ,

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