METHOD FOR TESTING WHETHER A VEHICLE AND DRIVER ASSISTANCE SYSTEM HAS VIOLATED THE BOUNDARY OF A DRIVABLE AREA

Description

[0001] The invention relates to the field of driver assistance systems for vehicles. In particular, the invention relates to a robust method for testing whether a vehicle guided by a driver assistance system violates the limits of the permissible clearance when driving along a trajectory.

[0002] Driver assistance systems in vehicles are generally known. Furthermore, distance-based methods are known that check whether the vehicle, which is to be moved along a trajectory, maintains the specified distance to the boundaries of the drivable area along the entire path of movement described by the trajectory. This is done taking into account the vehicle geometry, i.e., in particular the area created by projecting the vehicle body contour onto the road surface.

[0003] Furthermore, methods are known that check whether an intersection point occurs between the vehicle's travel corridor, i.e., the area swept out by the projection of the vehicle body contour onto the roadway when the vehicle moves along its trajectory, and the boundary lines of the drivable area, i.e., whether the travel corridor crosses a boundary of the drivable area. In known methods, the intersection point with the boundary of the drivable area must be calculated.

[0004] A problem with the known methods is that they are computationally very expensive, as systems of equations must be solved to determine the distance of the vehicle to the boundaries of the drivable area or the intersection point of a section of the vehicle body contour with a boundary line. Furthermore, it cannot always be guaranteed that the solution of the system of equations will yield real solutions. If no real solutions are found, further verification is necessary.

[0005] Document CN 1 02 295 004 A discloses a lane departure warning method comprising the following steps: providing the status information and environmental information of the current vehicle movement by means of a vehicle sensor, lane prediction using a driving behavior model of a human driver, prediction of the possible lane range of a vehicle within a certain time period in the future by combining it with the vehicle kinematics and a kinetic model, with a lane departure warning decision, wherein the vehicle's movement safety is analyzed by taking the relative relationship between the computation time from a possible lane of the vehicle to a detection point area on the lane marking line and a preset threshold time as an index of the lane departure warning.

[0006] Document US 2012 / 0212612A1 discloses a lane departure warning device for issuing a warning signal upon detecting that a vehicle has left a lane, wherein the lane departure warning device estimates the absence of lane markings.

[0007] Publication KR 10 1 406 316 B1 describes a device and a method for lane detection, whereby a warning zone within the lane is defined based on a detected lane. If the vehicle leaves this zone, a warning is issued.

[0008] The paper by Risack, R., N. Mohler, and W. Enkelmann, "A video-based lane keeping assistant," published in the Proceedings of the IEEE Intelligent Vehicles Symposium 2000 (Cat. No. 00TH8511), presents various methods for detecting lane departures. One such method is the calculation of the "time to line crossing" based on the current trajectory and vehicle dynamics. Different vehicle dynamics models are used for this calculation, specifically determining the intersection points of the vehicle dynamics curve with the lane markings.

[0009] From EP 3 344 519 A1, a device for reversing an articulated vehicle combination is known, comprising at least two vehicle units connected to each other via at least one articulated joint. The device further comprises means for recording and storing a plurality of global positions of a local position of the vehicle combination, at least one sensor attached to the vehicle combination for recording data representing a plurality of environmental properties, and a control unit arranged to record a set of global positions when the vehicle combination moves forward and a set of data representing environmental properties recorded during forward movement.Furthermore, vehicle control input data for controlling the vehicle combination during a reverse movement of the vehicle combination are determined, wherein the control unit is adapted to identify properties of the environment, including asphalt and grass, by means of a signal analysis function in the form of an image analysis function, and wherein the control unit is arranged to determine a swept area of ​​the vehicle combination based on at least the set of global positions.

[0010] EP 3 323 697 A1 relates to a method for planning a trajectory for the autonomous parking of a motor vehicle in a parking area with multiple parking spaces, largely without the need for complex sensors, wherein a first detection device of the parking area detects the dimensions of the geometric figure relating to the motor vehicle, a second detection device of the parking area detects the occupancy of the multiple parking spaces, and a drivable area or restricted area of ​​the parking area is determined on the basis of a map of the parking area, and on the basis of the detected parking space occupancy, a control unit of the parking area plans the trajectory for moving the geometric figure to an area of ​​the map representing a free parking space.

[0011] Based on this, the object of the invention is to provide a method that enables reliable testing of the violation of a boundary of a drivable area with low computational effort.

[0012] The problem is solved by a method having the features of independent claim 1. Preferred embodiments are the subject of the dependent claims. A driver assistance system configured to check for violations of the boundary of a drivable area is the subject of dependent claim 8.

[0013] According to a first aspect, a method for testing whether a vehicle has violated the boundary of a drivable area is disclosed. The vehicle has a driver assistance system designed to move the vehicle automatically or semi-automatically along a trajectory. Furthermore, the driver assistance system is configured to perform the test procedure in the following steps: First, information about at least one boundary line of the drivable area is received. Thus, the drivable area is defined, in particular, by the at least one boundary line, preferably a left and a right boundary line, which are spaced apart from each other and, for example, define a lane. The information can be provided by an environmental sensing unit of the vehicle, which creates an environmental model of the surroundings of the vehicle.The boundary line can, for example, define a boundary in open space, specifically defining a lane along which the vehicle is to travel. Alternatively, the boundary line can characterize an object in the vehicle's vicinity.

[0014] Preferably, the at least one boundary line is defined by a plurality of points, i.e., by a line segment consisting of several straight lines, each extending between two adjacent points. Alternatively, the boundary line can also be formed by a continuous line.

[0015] In addition, information about the vehicle's driving corridor is received. The driving corridor is, in particular, the area swept out by the projection of the vehicle body contour onto the road surface when the vehicle traverses the trajectory. InIn other words, the driving corridor is in particular a tube-like area with a width at least equal to the vehicle width (or wider if a safety buffer is included).

[0016] A first and a second point are selected on at least one boundary line of the drivable area. When information is received regarding two boundary lines, particularly a left and right boundary line of the drivable area, a first and second point are preferably selected on each of the two boundary lines. The first point is located behind the second point on the same boundary line in the vehicle's direction of travel. These points thus define a section of the at least one boundary line, with reference to which the check is performed to determine whether or not a boundary line violation occurs when traversing the trajectory.

[0017] Furthermore, at least one or exactly one third point is defined, lying on the edge of the vehicle's travel corridor. The vehicle's travel corridor can be defined either by continuous lines or by a multitude of vehicle body contours positioned at different locations along the trajectory. The vehicle body contour can, for example, be formed by a polygon, in particular a rectangle, which at least approximately describes the vehicle body contour when viewed from above. The vehicle body contour can be chosen to be larger than the actual vehicle body contour in order to provide a safety margin.

[0018] Subsequently, the position of at least one third point relative to the line between the first and second points, which lie on the same boundary line, is determined, at least temporarily, by determining the direction of rotation for at least the third point. Furthermore, it is checked whether the determined direction of rotation is clockwise or counterclockwise. In In other words, the three points, two of which lie on the same boundary line and one of which indicates a point in the vehicle's travel corridor, are connected by a line. The direction of rotation can be determined, in particular, by traversing the line in such a way that the distance between the two points on the boundary line of the drivable area is covered in the direction of travel.

[0019] InIn the next step, based on the verified direction of rotation of at least the third point, it is checked whether the vehicle has violated the boundary of the drivable area.

[0020] The method has the technical advantage that, due to its rotation-direction-based testing procedure, a technically simple test with low computational effort is possible, as the testing procedure is point-based. This allows for the use of computationally efficient vector calculus methods, thus eliminating the need to solve a computationally intensive system of equations. Furthermore, the testing procedure makes it possible to determine whether the drivable area has been completely left, which improves the reliability of the testing procedure.

[0021] According to one embodiment, the direction of rotation is determined by identifying the direction of rotation for the third point when traversing a line segment formed from the first point, via the second point, to the third point. A discrepancy between the determined direction of rotation and an expected direction of rotation indicates, in particular, that a limit has been exceeded.

[0022] According to one embodiment, the third point is a vehicle vertex of a polygon, in particular a quadrilateral, specifically a rectangle, which replicates the vehicle body contour. Thus, the vehicle body contour is approximated, in particular, by a rectangle with four corners.

[0023] According to one embodiment, the at least one or exactly one boundary line of the drivable area is approximated by several spaced-apart points, and pairs of points on the boundary line are selected sequentially as first and second points and used to determine the direction of rotation and to check whether the boundary of the drivable area has been violated. This allows the violation of the drivable area to be checked iteratively based solely on pairs of points on the boundary line, without a system of equations.

[0024] According to one embodiment, the drivable area has a left and a right boundary line, spaced apart from each other, which define a driving lane. The vehicle body contour is approximated by a polygon with two left and two right vehicle vertices. For the left vehicle vertices, the position of at least the two left vehicle vertices relative to the line between the first and second points, which lie on the left boundary line, is checked, at least temporarily. Furthermore, it is preferred that a rotation direction is determined for at least the two left vehicle vertices by determining a rotation direction for each left vehicle vertex as it traverses a polygon formed from the first point via the second point to the respective vehicle vertex. Thus, at least two rotation directions are determined.The system then checks whether the specified rotation directions are clockwise. Based on these checked rotation directions, it is then verified whether the vehicle violates the left boundary line of the drivable area. This allows the method to be applied advantageously and with reduced computational effort to ensure compliance with the left boundary line of a given lane.

[0025] According to one embodiment, the drivable area has a left and a right boundary line, spaced apart from each other, which define a driving lane. The vehicle body contour is approximated by a polygon with two left and two right vehicle vertices. For the right vehicle vertices, the position relative to the line between the first and second points, which lie on the right boundary line, is checked, at least temporarily. Furthermore, it is preferred that a rotation direction is determined for each right vehicle vertex by determining a rotation direction for each right vehicle vertex as it traverses a line formed from the first point via the second point to the respective vehicle vertex. Thus, at least two rotation directions are determined. Subsequently, it is checked whether the determined rotation directions are oriented counterclockwise.Based on the tested rotation directions, the system checks whether the vehicle violates the right-hand boundary line of the drivable area. This allows the method to be applied advantageously and with reduced computational effort to ensure compliance with the right-hand boundary line of a given lane.

[0026] According to a preferred further development, the determination of the direction of rotation and the verification of the direction of rotation are carried out for at least two vehicle corner points, particularly preferably for all vehicle corner points that replicate the vehicle body contour.

[0027] According to one embodiment, the boundary line of the drivable area refers to a boundary line of a lane or roadway boundary.

[0028] Another aspect of the invention relates to a driver assistance system designed to detect whether a vehicle has crossed the boundary of a drivable area. The driver assistance system comprises several, in particular at least two, sensors distributed around the vehicle and a processing unit for processing the information provided by the sensors. The processing unit is configured to perform the following steps: Receiving information about at least one boundary line of the drivable area; receiving information about a driving corridor of the vehicle, wherein the driving corridor is the area swept out by a projection of the vehicle body contour onto the roadway when traversing the trajectory; Selecting a first and a second point on the at least one boundary line of the drivable area, wherein the first point lies behind the second point in the direction of travel of the vehicle; determining at least or exactly one third point located on the vehicle; checking the position of at least the third point relative to the line between the first and second points, ensuring that a direction of rotation is determined for at least the third point, and verifying whether the determined direction of rotation is clockwise or counterclockwise; determining, based on the verified direction of rotation of the at least third point, whether the vehicle violates the at least one boundary line of the drivable area.

[0029] The terms "approximately", "essentially" or "about" mean, within the meaning of the invention, deviations from the respective exact value by + / - 10%, preferably by + / - 5% and / or deviations in the form of changes that are insignificant for the function.

[0030] Further developments, advantages, and possible applications of the invention will also become apparent from the following description of exemplary embodiments and from the figures. All features described and / or illustrated are, individually or in any combination, fundamentally the subject matter of the invention, irrespective of their compilation in the claims or their cross-reference. The content of the claims is also incorporated into the description.

[0031] The invention will be explained in more detail below with reference to exemplary embodiments shown in the figures. The figures show: Fig. 1 is an exemplary schematic top view of a vehicle equipped with a driver assistance system comprising multiple sensors and a processing unit; Fig. 2 shows exemplary different arrangements of points A, B, and C, illustrating the resulting direction of rotation for a given direction of rotation of the points; Fig. 3 shows, by way of example, the movement of a vehicle along a trajectory through a pair of boundary lines defining a lane and the exemplary application of the rotation direction method for checking for violations of the lane boundary lines; and Fig. 4 shows, by way of example, the movement of a vehicle based on a trajectory along a lane, where a violation of the left lane boundary line occurs; Fig. 5 is a flowchart illustrating the steps of the procedure for checking for violations of a boundary of a drivable area.

[0032] Figure 1Figure 1 shows, in a schematic top view, an exemplary model of a vehicle 1 equipped with a driver assistance system for performing automatic or semi-automatic driving maneuvers. The driver assistance system can be specifically designed to recognize areas that the vehicle 1 can traverse automatically or semi-automatically and to control the vehicle 1 in such a way that it does not violate the boundaries of this traversable area. The traversable area could, for example, be a lane with left and right boundary lines. Alternatively, the traversable area could be restricted by one or more surrounding objects with which a collision is to be avoided.

[0033] Vehicle 1 has several sensors 2 that detect its surroundings. These sensors 2 are connected to a processing unit 3 of the driver assistance system, which processes the sensor information and provides information about at least one boundary line of the drivable area. This environmental detection enables the driver assistance system to define local areas within which vehicle 1 can be driven without collision.

[0034] The driver assistance system is also designed to determine a trajectory along which the vehicle 1 moves during autonomous or semi-autonomous driving. While traversing this trajectory, the vehicle moves within a driving corridor. This corridor is defined by the area swept or temporarily occupied by the vehicle body during movement. The vehicle has a circumferential body contour, which can be seen, for example, from a bird's-eye view of the vehicle 1. Projecting this body contour vertically downwards onto the roadway defines the area of ​​the roadway occupied by the vehicle 1. This area must be completely clear to allow the vehicle 1 to move without collision. The driving corridor is therefore tube-like and has a width at least equal to the width of the vehicle body contour.The driving corridor can also be wider than the vehicle width to increase the safety of the procedure.

[0035] To determine whether vehicle 1 violates a boundary of the drivable area, a rotation direction-based test procedure can be applied.

[0036] Fig. 2 shows two ways in which a triplet of points A, B and C can be arranged.

[0037] For example, the line between the first and second points B and C forms a section of a boundary line of the drivable area. The third point A could, for example, be a vertex of the vehicle body contour of vehicle 1. Points A, B, and C define a triangle, generally a polygon. By traversing the polygon along the points in a predefined sequence, for example, from point B via point C to point A, the position of point A relative to the line between points B and C can be determined. If the rotation direction is clockwise when traversing the polygon, it can be deduced that point A lies to the right of line BC. Conversely, if the rotation direction is counterclockwise when traversing the polygon, it can be deduced that point A lies to the left of line BC (right-hand representation of the Fig. 2 ).

[0038] Fig. 3Figure 1 shows an application example of the described method, in which the vehicle 1 is moved along a trajectory T in the direction of travel TD on a lane defined by a left boundary line G1 and a right boundary line G2. The boundary lines G1 and G2 can be represented by discrete points spaced apart from each other. In the embodiment shown in Figure 2, the following applies: Fig. 3 Points B and C are two points of the left boundary line G1 and points B' and C' are two points of the right boundary line G2.

[0039] The body contour of vehicle 1 is represented by a rectangle. The size of the rectangle is chosen such that all areas of vehicle 1 lie within this body contour, including, for example, the side mirrors of vehicle 1.

[0040] To ensure that vehicle 1 can move along trajectory T without collisions, it must be verified that the travel corridor of vehicle 1, which results from the movement of the vehicle body contour along trajectory T, does not intersect with the boundary lines G1 and G2. In particular, the travel corridor of vehicle 1 can be a tube-like area that must lie within the boundary lines G1 and G2 to guarantee that trajectory T is collision-free.

[0041] The collision-free verification of the trajectory T can be performed iteratively based on discrete vehicle positions of vehicle 1, as described in Fig. 3 as indicated by the multitude of rectangles that represent vehicle 1.

[0042] At a defined vehicle position, it must be checked whether the left vehicle contour line is to the right of the left boundary line G1 and whether the right vehicle contour line is to the left of the right boundary line G2. In the illustrated embodiment, this check can be performed using the front left and rear left corners, and the front right and rear right corners, respectively. More specifically, it must be checked whether the front left and rear left corners are in the same position relative to the left boundary line G1, i.e., whether both are to the right of the left boundary line G1. The same applies to the front right and rear right corners with respect to the right boundary line G2. These two corners must also be in the same position relative to the right boundary line G2, i.e., whether both are to the left of the right boundary line G2.

[0043] In this test, for example, a pair of points on the left boundary line G1 of the lane is determined, located near the left vehicle contour line. In the illustrated embodiment, these are points B and C. The front left corner of vehicle 1 is designated by point A. The line formed by the point sequence BCA has a clockwise direction of rotation.

[0044] The same check is now performed for the rear left corner of vehicle 1 relative to points B and C. If the polygonal line is traversed from point B to C, then back to B via the rear left corner, a clockwise direction of rotation is also obtained. This check confirms that both corner points of the left vehicle contour line lie on the same side of the left boundary line G1, meaning the left vehicle contour line does not intersect the left boundary line G1, thus ensuring a collision-free path with the left boundary line G1. Furthermore, it can be determined that both corner points of the left vehicle contour line lie to the right of the left boundary line G1.

[0045] Analogous testing is performed with respect to the two corner points of the right vehicle contour line relative to the right boundary line G2.

[0046] As in Fig. 3As shown, the right boundary line G2 is also represented by a multitude of points, with points B' and C' defining a line that forms a segment of the right boundary line G2. To determine whether vehicle 1 crosses this right boundary line G2 when traversing the driving corridor, the algorithm described above is applied analogously to the corner points of the right vehicle contour line. Thus, for the front right corner of the vehicle contour line A' and the resulting polygon B'-C'-A', the direction of rotation is determined, which results from traversing the polygon in the direction described above. In the illustrated embodiment, this direction is counterclockwise.

[0047] A similar check is now performed for the rear right corner of vehicle 1 relative to points B' and C'. If the polygonal line is traversed from point B' to C', across the rear right corner of vehicle 1, and back to B', a counterclockwise rotation direction is also observed. This check confirms that both corner points of the right vehicle contour line lie on the same side of the right boundary line G2, meaning the right vehicle contour line does not intersect the right boundary line G2 and therefore there is no collision with the right boundary line G2. Furthermore, it can be determined that both corner points of the right vehicle contour line lie to the left of the right boundary line G2.

[0048] The test steps described above are preferably performed iteratively for several vehicle positions along the driving corridor and for different sections (defined by pairs of points BC or B'-C') of the boundary lines G1 and G2 in order to guarantee the collision-free nature of the trajectory T.

[0049] Fig. 4 shows an example where the trajectory T is determined such that the driving corridor of vehicle 1 crosses the left boundary line G1 in the area marked with the oval, thereby resulting in a violation of a boundary of the drivable area.

[0050] Any discrepancy with the expected direction of rotation indicates, in particular, that a limit has been exceeded. In this embodiment, the expected directions of rotation for the line segment of the respective vehicle vertices A FL , A RL , A FR , A RR are as follows: Ordered sequence of points in the line Expected direction of rotation ( front left vehicle corner point A FL , BL , CL ) Clockwise (rear left vehicle corner point A RL) , BL, CL ) Clockwise (front right corner of vehicle A FR , BR , CR ) Counterclockwise (rear right vehicle corner A RR , BR , CR ) Counterclockwise

[0051] The section of boundary line G1 in the area of ​​vehicle 1 is defined by points BL and CL. The front left corner of vehicle 1 is designated as point A FL. The line formed by the points BL - CL - A FL rotates counterclockwise. Applying the proposed method to the rear left corner of vehicle 1, designated as point A RL, with respect to boundary line G1, which is again defined by points BL and CL, the line formed by points BL - CL - A RL rotates clockwise. Since the rotation directions for the front and rear corners are different, the proposed method can detect a violation of boundary line G1.

[0052] To determine that vehicle 1 is not completely outside the drivable area, it can be useful to check the position of the left and right corner pairs of the vehicle contour line relative to at least one boundary line G1, G2 in each cycle or at longer time intervals. For example, if the left corners of vehicle 1's contour line rotate counterclockwise relative to the line defined by points BL and CL, and this rotation indicates that the left corners of the vehicle body contour are to the left of the left boundary line G1, it can be concluded that vehicle 1 is already outside the drivable area at this point on trajectory T, thus violating the boundary of the drivable area.

Claims

1. A computer-implemented method for checking whether a vehicle (1) travelling along a trajectory (T) has violated a boundary of a drivable area, wherein the method comprises the following steps: a) receiving information on at least one boundary line (G1, G2) of the drivable area (S10); b) receiving information on a driving corridor of the vehicle (1) (S11); characterised in that the method further comprises the following steps: c) selecting a first and a second point (B, C, B', C') on the at least one boundary line (G1, G2) of the drivable area, wherein the first point (B, B') is behind the second point (C, C') in the direction of travel (TD) of the vehicle (1) (S12); d) defining at least one third point (A, A', AFL, AFR, ALR, ARR) which is located on the edge of the driving corridor of the vehicle (1) (S13); e) checking the position of the at least third point (A, A', AFL, AFR, ALR, ARR) relative to the line between the first and second points (B, C, B', C', BL, CL) to check that, at least for the third point (A, A', AFL, AFR, ALR, ARR), a rotation direction determination is carried out and that it is checked whether the determined rotation direction is oriented clockwise or counterclockwise (S14); f) ascertaining, based on the checked rotation direction of the at least third point (A, A', AFL, AFR, ALR, ARR), whether the vehicle (1) violates the at least one boundary line (G1, G2) of the drivable area (S15).

2. The method as claimed in claim 1, characterised in that the determination of the rotation direction is carried out by determining a rotation direction for the third point (A, A') when traversing a polyline formed from the first point (B, B') via the second point (C, C') to the at least third point (A, A').

3. The method as claimed in claim 1 or 2, characterised in that the at least one boundary line (G1, G2) of the drivable area is approximated by multiple points spaced apart from each other, and in that point pairs of the boundary line are selected sequentially as first and second points (B, C, B', C') and used for ascertaining the rotation direction and for checking whether the boundary of the drivable area has been violated.

4. The method as claimed in any of the preceding claims, characterised in that the at least third point (A, A', AFL, AFR, ALR, ARR) is a vehicle vertex of a polygon that replicates the vehicle body contour of the vehicle (1).

5. The method as claimed in any one of the preceding claims, characterised in that the drivable area has a left and a right boundary line (G1, G2) which are spaced apart from each other and define a driving lane, in that the vehicle body contour is approximated by a polygon with two left and two right vehicle vertices, and in that the position of at least the two left corners relative to the line between the first and second points, located on the left boundary line (G1), is checked at least intermittently, in that, at least for the two left vehicle vertices, a rotation direction is determined in each case, namely by determining a rotation direction for each left vehicle vertex when traversing a polyline formed starting from the first point via the second point to the respective vehicle vertex, and in that it is checked whether the two directions of rotation are oriented clockwise.

6. The method as claimed in any one of the preceding claims, characterised in that the drivable area has a left and a right boundary line (G1, G2) which are spaced apart from each other and define a driving lane, in that the vehicle body contour is approximated by a polygon with two left and two right vehicle vertices, and in that the position of the two right vehicle vertices relative to the line between the first and second points, located on the right boundary line (G2), is checked at least intermittently, in that for the two right vehicle vertices, a rotation direction is determined in each case, namely by determining a rotation direction for each right vehicle vertex when traversing a polyline formed starting from the first point via the second point to the respective vehicle vertex, and in that it is checked whether the two directions of rotation are oriented counterclockwise.

7. The method as claimed in any of the preceding claims, characterised in that the rotation direction determination and the rotation direction checking are carried out for all vehicle vertices that replicate the vehicle body contour.

8. A driver assistance system designed to check whether a vehicle (1) has violated a boundary of a drivable area, wherein the driver assistance system comprises multiple sensors (2) arranged distributed around a vehicle (1) and a computing unit (3) for processing the information provided by the sensors (2), wherein the computing unit (3) is configured to perform the following steps: a) receiving information on at least one boundary line of the drivable area; b) receiving information on a driving corridor of the vehicle (1), wherein the driving corridor is the area covered by a projection of the vehicle body contour (F) onto the road when driving along the trajectory (T) (S11); characterised in that the method further comprises the following steps: c) selecting a first and a second point (B, C, B', C') on the at least one boundary line (G1, G2) of the drivable area, wherein the first point (B, B') is behind the second point (C, C') in the direction of travel (TD) of the vehicle (1); d) defining a third point (A, A', AFL, AFR, ALR, ARR) which is located on the edge of the driving corridor of the vehicle (1); e) checking the position of at least the third point (A, A', AFL, AFR, ALR, ARR) relative to the line between the first and second point (B, C, B', C'), to verify that, at least for the third point (A, A', AFL, AFR, ALR, ARR), a rotation direction determination is carried out, and verifying whether the determined rotation direction is oriented clockwise or counterclockwise; f) ascertaining, based on the checked rotation direction of the at least third point (A, A', AFL, AFR, ALR, ARR), whether the vehicle (1) violates the at least one boundary line (G1, G2) of the drivable area.