Method for the geometric representation of a vehicle area of a vehicle for the purpose of collision detection

Abstract

A method for the geometric representation of a vehicle area (1) of a vehicle for the purpose of collision detection, wherein the vehicle area (1) has a boundary (2), comprising the method steps of performing a medial axis transformation of the vehicle area (1) to generate a vehicle area skeleton (4) and performing a point classification of points of the vehicle area skeleton (4) to determine front corner region points (5, 6) and rear corner region points (7, 8), and a front wheelbase point (9) and a rear wheelbase point (10), and also performing a circle decomposition of the vehicle area (1), wherein each circle of the circle decomposition has a maximum area exceedance value (17).

Claims

1. Method for the geometric representation of a vehicle area of a vehicle for the purpose of collision detection, wherein the vehicle area has a boundary, comprising the method steps of: (a) performing a medial axis transformation of the vehicle area to generate a vehicle area skeleton, and performing a point classification of points of the vehicle area skeleton to determine front corner region points and rear corner region points, and a front wheelbase point and a rear wheelbase point; (b) performing a circle decomposition of the vehicle area, wherein each circle of the circle decomposition has a maximum area exceedance value, including: (i) (I) generating a first circle, the center of which is the front wheelbase point and which has a first radius, and generating a second circle, the center of which is the rear wheelbase point and which has the first radius; wherein the connection between the front and the rear wheelbase point corresponds to a first skeleton connecting line; (II) performing a verification step to determine whether an area of the vehicle area assigned to the first skeleton connecting line, with the rear and front wheelbase point as end points, is completely covered; (III) if the verification step is negative, generating an n-th circle, where n=3, . . . , on the first skeleton connecting line, with the first radius; incrementing n and performing step (II) again; (ii) proceeding from the front wheelbase point towards an n.sub.v-th front corner region point, n.sub.v=1, 2, . . . , along an n.sub.v-th front skeleton connecting line between the front wheelbase point and the n.sub.v-th front corner region point; (I) generating an n.sub.v-th front circle on the n.sub.v-th front skeleton connecting line, with a minimum radius, and iteratively adapting the minimum radius of the n.sub.v-th front circle until the maximum area exceedance value condition is satisfied; (II) performing a verification step to determine whether an area of the vehicle area assigned to the n.sub.v-th front skeleton connecting line is completely covered; (III) if the verification step is negative, generating a (n.sub.v+1)-th front circle, with the minimum radius, on the n.sub.v-th front skeleton connecting line, and iteratively adapting the minimum radius of the (n.sub.v+1)-th front circle until the maximum area exceedance value condition is satisfied, incrementing n.sub.v, and performing step (II) again; (iii) proceeding from the rear wheelbase point towards an n.sub.h-th rear corner region point (7, 8), n.sub.h=1, 2, . . . , along an n.sub.h-th rear skeleton connecting line between the rear wheelbase point and the n.sub.h-th rear corner region point; (I) generating an n.sub.h-th rear circle, with the minimum radius, and iteratively adapting the minimum radius of the n.sub.h-th rear circle until the maximum area exceedance value condition is satisfied; (II) performing a verification step to determine whether an area of the vehicle area assigned to the n.sub.h-th rear skeleton connecting line is completely covered; (III) if the verification step is negative, generating an (n.sub.h+1)-th rear circle, with the minimum radius, on the n-th rear skeleton connecting line and iteratively adapting the minimum radius of the (n.sub.h+1)-th rear circle until the maximum area exceedance value condition is satisfied, incrementing n.sub.h, and performing step (II) again.

2. Method according to claim 1, wherein when the point classification is performed, a first and a second lateral corner region point are defined, wherein the connecting line between the first and the second lateral corner region point corresponds to a lateral skeleton connecting line, wherein the first lateral skeleton connecting line and the second lateral skeleton connecting line intersect at a first point, wherein the first lateral skeleton connecting line is formed by the skeleton connecting line between the first point and the first corner region point, and a second lateral skeleton connecting line is formed by the skeleton connecting line between the first point and the second lateral corner region point, wherein, proceeding from the first point towards the first lateral corner region point along the first lateral skeleton connecting line, or proceeding from the first point towards the second lateral corner region point along the second lateral skeleton connecting line: (I) generating an n.sub.s-th lateral circle on the first or second lateral skeleton connecting line, with the minimum radius, and iteratively adapting the minimum radius of the n.sub.s-th lateral circle until the maximum area exceedance value condition is satisfied; (II) performing a verification step to determine whether an area of the vehicle are assigned to the first or second lateral skeleton connecting line is completely covered; (III) if the verification step is negative, generating an (n.sub.s+1)-th lateral circle with the minimum radius, on the first or second lateral skeleton connecting line, and iteratively adapting the minimum radius of the (n.sub.s+1)-th lateral circle until the maximum area exceedance value condition is satisfied, incrementing n.sub.s and performing step (II) again.

3. Method according to claim 1, wherein in the event of a negative verification step, the third circle is determined proceeding from the first circle, wherein the first circle intersects the boundary at a minimum of four points of intersection, wherein a first point of intersection and a second point of intersection are opposite each other with respect to the first skeleton connecting line, and wherein a center of the third circle is determined by means of the first and the second point of intersection; or, in the event of a negative verification step, the third circle is determined proceeding from the second circle, wherein the second circle intersects the boundary at a minimum of four points of intersection, wherein a first point of intersection and a second point of intersection are opposite each other with respect to the first skeleton connecting line, and wherein a center of the third circle is determined by means of the first and the second point of intersection; and wherein, in the case of a repeated negative verification step, the (n+1)-th circle is determined proceeding from the n-th circle, wherein the n-th circle intersects the boundary at a minimum of four points of intersection, wherein a first point of point of intersection and a second point of point of intersection are opposite each other with respect to the first skeleton connecting line, and wherein a center of the (n+1)-th circle is determined by means of the first point of point of intersection and the second point of point of intersection.

4. Method according to claim 1, wherein proceeding from the first circle, the first front circle is determined, wherein the first circle intersects the boundary at a minimum of four points of intersection, wherein a third point of intersection and a fourth point of intersection are opposite each other with respect to the first front skeleton connecting line, and wherein a center of the first front circle is determined by means of the third and fourth points of intersection, and wherein in the event of a negative verification step, proceeding from the n.sub.v-th front circle, the (n.sub.v+1)-th circle is determined, wherein the n.sub.v-th circle intersects the boundary at a minimum of two points of intersection, wherein a first point of intersection and a second point of intersection are opposite each other with respect to the first front skeleton connecting line, wherein the center of the (n.sub.v+1)-th front circle is determined by means of the first point of intersection and the second point of intersection.

5. Method according to claim 1, wherein the first radius corresponds to a maximum permitted radius, which is formed as a function of a vehicle width and the maximum area exceedance value.

6. Method according to claim 1, wherein the circle decomposition has a total area exceedance value relative to the vehicle area, wherein the total area exceedance value is dependent on the maximum area exceedance value for each circle, a grid resolution and a minimum radius for each circle.

7. Method according to claim 1, wherein the point classification is performed from a prespecified vehicle center in such a way that the points with the greatest distances from the vehicle center are defined as the corner region points, and the points of the vehicle center which constitute a Y node or are arranged near a Y node are defined as the wheelbase points.

8. Method according to claim 1, wherein after the circle decomposition has been carried out, a rectangle decomposition of each circle is carried out in such a way that each circle is covered by rectangles, wherein, upon a movement of the vehicle, an integral image of an occupancy map is calculated, wherein the movement of the vehicle results in a transformation matrix being applied to each circle, wherein each rectangle is checked for occupancy by means of rapid collision detection.

9. Method according to claim 1, wherein the circle decomposition is performed exactly once.

Description

[0076] FIG. 1 shows the geometric representation of a vehicle area according to the prior art;

[0077] FIG. 2A is a medial axis transformation and point classification;

[0078] FIG. 2B shows the process of generating the first and second circles;

[0079] FIG. 2C shows the process of generating n-th circles;

[0080] FIG. 2D shows the process of generating the first rear circle;

[0081] FIG. 2E shows the process of complete circle decomposition of the vehicle area;

[0082] FIG. 2F shows the schematic representation of the coverage of a rear skeleton connecting line, and the determination of a first rear circle;

[0083] FIG. 2G shows the schematic representation according to FIG. 2F, and the determination of a second rear circle;

[0084] FIG. 3 shows the determination of the minimum radius;

[0085] FIG. 4 shows the rectangle decomposition of the circle decomposition according to FIG. 2E.

[0086] In the drawings, identical components are always provided with the same corresponding reference signs. For the sake of clarity, in some of the drawings, components that have been identified elsewhere may not be provided with a reference sign.

[0087] FIG. 1 shows a geometric representation of a vehicle area 1 with a boundary 2, wherein a boundary frame 3 is provided in the form of a rectangle which surrounds the vehicle area 1. The boundary frame 3 has been covered by means of a circle decomposition in such a way that a fixed number of circles is provided, in this case 10 circles, with a fixed radius.

[0088] As can be seen, a corresponding area exceedance value 17 is shown for each circle, and is relatively large in relation to the vehicle area 1 of the vehicle—in the present case, approximately one third of the area of each circle, and a considerable amount in the front region and in the rear region—such that it is necessary to maintain large distances between an object and the vehicle to prevent the detection of a collision, which is disadvantageous when maneuvering or parking.

[0089] Accordingly, the total area exceedance value, which can for example be formed by the sum of the individual area exceedance values, is considerably too large.

[0090] According to the present invention, the entire area exceedance value is to be minimised by the method according to the invention, in order to be able to improve the collision detection.

[0091] In the following drawings, the method according to the invention is described in accordance with a particularly preferred embodiment.

[0092] FIG. 2A shows a vehicle area skeleton 4 of the vehicle area 1, which was obtained by means of a medial axis transformation (MAT). In the present case, the vehicle area skeleton 4 comprises a first skeleton connecting line 16, a first front skeleton connecting line 20, a second front skeleton connecting line 21, a first rear skeleton connecting line 22, a second rear skeleton connecting line 23, a first lateral skeleton connecting line 24, and a second lateral skeleton connecting line 25.

[0093] Furthermore, a point classification has been carried out, the points having been classified with respect to a vehicle center 26, wherein the point classification is performed from the vehicle center 26 in such a way that the points with the greatest distances from the vehicle center 26 are defined as the corner region points, and the points of the vehicle center which represent a Y node or are located near a Y node are defined as the wheelbase points. A first front corner region point 5, a second front corner region point 6, a first rear corner region point 7, a second rear corner region point 8, a first lateral corner region point 11, a second lateral corner region point 12, a front wheelbase point 9, and a rear wheelbase point 10 were obtained in this process.

[0094] The first front corner region point 5 and the front wheelbase point 9 form the edge points of the first front skeleton connecting line 20, the second front corner region point 6 and the front wheelbase point 9 form the edge points of the second front skeleton connecting line 21, the first rear corner region point 7 and the rear wheelbase point 10 form the edge points of the first rear skeleton connecting line 22, and the second rear corner region point 8 and the rear wheelbase point 10 form the edge points of the second rear skeleton connecting line 23.

[0095] The line connecting the first lateral corner region point 11 and the second lateral corner region point 12 corresponds to a lateral skeleton connecting line 28, wherein the first lateral skeleton connecting line 16 and the lateral skeleton connecting line 28 intersect at a first point 27, wherein a first lateral skeleton connecting line 24 is formed by the skeleton connecting line between the first point 27 and the first corner region point 11, and a second lateral skeleton connecting line 25 is formed by the skeleton connecting line between the first point 27 and the second lateral corner region point 12.

[0096] The first lateral corner region point 11 and the second corner region point correspond to each of the exterior mirrors of the vehicle, respectively.

[0097] The term “vehicle center 26”, indicated by the coordinates (x.sub.c,y.sub.c), is used to mean an average of the skeleton points, wherein the set of skeleton points P.sub.s(x.sub.s,y.sub.s), represented by:

[00004]$\left(x_c,y_c\right)=\left(\frac{x_{s,\max }+x_{s,\min }}{2},\frac{y_{s,\max }+y_{s,\min }}{2}\right),$

wherein x.sub.s,max is the maximum value and x.sub.s,min is the minimum value of the x-coordinate, and Y.sub.s,max is the maximum value and Y.sub.s,min is the minimum value of the y-coordinate.

[0098] The term “Y node” is used to designate the point at which the lines of the Y meet.

[0099] In addition, further points may be classified which correspond to lateral corner region points which correspond to the position of the mirrors of the vehicle. The lateral corner region points are those points which are at a distance from the center of the vehicle and do not correspond to any other corner region point.

[0100] A subsequent method step describes performing a circle decomposition of the vehicle area, in which each circle of the circle decomposition has a maximum area exceedance value.

[0101] According to the invention, a first circle 13 and a second circle 14 are generated, wherein the first circle 13 and the second circle 14 have a first radius 18. The first radius 18 is dependent on a vehicle width 29 and on the maximum area exceedance value. The vehicle width 29 corresponds to an extension of the vehicle in a width direction B, but preferably without taking the exterior mirrors into account.

[0102] The first radius 18 is then to be selected according to the vehicle width specifications and the maximum area exceedance value.

[0103] As can also be seen from FIG. 2B, the area assigned to the first skeleton connecting line 16 is not yet covered by the first circle 13 and the second circle 14, such that further circles are generated, beginning with a third circle 15.

[0104] In the present case, proceeding from the second circle 14, it can be seen that the second circle 14 intersects the boundary 2 at a minimum of two points of intersection, as a result of the requirement for the first radius 18—a first point of point of intersection 30 and a second point of point of intersection 31. These points of intersection 30, 31 are opposite each other with respect to the first skeleton connecting line 16.

[0105] The third circle 15 can be easily constructed proceeding from the points of intersection 30, 31, with a center 32 and the first radius 18, as shown in FIG. 2C.

[0106] After the third circle is generated, a verification step is carried out to verify that the area assigned to the first skeleton connecting line 14 is completely covered. This is not the case here, such that a fourth circle 33 with a center 34 must be generated. In this case, proceeding from the points of intersection 30, 31 of the third circle 15 with the boundary 2, the center 34 is determined, and the fourth circle 33 with the first radius 18 is generated.

[0107] If necessary, additional circles could be generated with the same method, until the entire area assigned to the first skeleton connecting line 16 is covered.

[0108] The remaining areas to be covered, assigned to the front, rear and lateral skeleton connecting lines 20, 21, 22, 23, 24, 25, 28, must accordingly still be completely covered.

[0109] The procedure for the first rear skeleton connecting line 22 is described purely by way of example below in conjunction with FIG. 2D. The procedure for the other skeleton connecting lines 20, 21, 23, 24, 25, 28 is to be carried out analogously.

[0110] The second circle 14 further intersects the boundary 2 at a third point of intersection 35 and at a fourth point of intersection 36, as a result of which a center of the first rear circle 37 can be determined. The third point of intersection 35 and the fourth point of intersection 36 are opposite each other with respect to the first rear skeleton connecting line 22.

[0111] The center 38 of the first rear circle 37 is determined as a function of the points of intersection 35, 35, the position of the center on the first rear skeleton connecting line 22, and a minimum radius. The radius of the first rear circle 37 is iteratively increased until the requirement of the maximum area exceedance value is satisfied.

[0112] It is preferably provided that rear circles which lie in the previously formed circles of the first skeleton connecting line 16 are disregarded—that is, they are not generated. Rather, further circles of the first rear skeleton connecting line 22 are generated iteratively.

[0113] The complete circle decomposition is shown in FIG. 2E.

[0114] After the vehicle area 1 has been decomposed into circles, it is particularly preferably provided that the generated circles are further simplified by means of a rectangle decomposition.

[0115] Particularly preferred is a rectangle decomposition of a circle which is performed in such a way that each circle is covered by rectangles.

[0116] In this case, the minimum radius must be selected, optionally as a function of the grid resolution, in such a way that a circle can be represented by at least two rectangles.

[0117] FIG. 2F shows an example in which a plurality of rear circles are necessary in order to completely cover the area assigned to the corresponding rear skeleton connecting line (not shown here), since the first rear circle 37 does not completely cover it, since the maximum area exceedance value condition is already fulfilled. Therefore, in order to completely cover the area assigned to the rear skeleton connecting line, a further rear circle, the second rear circle 39, of the corresponding rear skeleton connecting line is determined, as can be seen in FIG. 2G.

[0118] The significance of this is shown in FIG. 3, wherein different circles with corresponding radii are shown for an example of a grid with a resolution of 0.1 m.

[0119] As can be seen, for the circle with a diameter of 0.6 m, the circle is represented by a single rectangle, since each cell lies at least partially within the circle. This is no longer the case with the other, larger diameters, such that each circle can be covered by at least two rectangles.

[0120] The idea behind a minimum circle radius is to minimise the total number of circles. According to the invention, the proposed method tries to cover the vehicle area 1 by means of a minimum number of circles within permitted boundary conditions, such as the maximum area exceedance value and the minimum radius.

[0121] FIG. 4 shows the circle decomposition of the vehicle area 1 with a rectangle decomposition that has been carried out. As can be seen from a comparison with FIG. 1, the coverage of the vehicle area 1 is selected to be significantly smaller, as is also shown by the inclusion of the boundary frame 3. The vehicle areas 1 with the boundary 2 and the boundary frame 3 of FIGS. 1 and 4 are identical, such that the difference from the prior art, shown in FIG. 1, can be clearly seen.

[0122] A further advantage of the illustrated decomposition and coverage of the vehicle area 1 is that circles are invariant upon rotation, such that it is only necessary to multiply the center of a circle by a rotation matrix for it to adapt to a movement of the vehicle.

[0123] The total calculation time for a collision detection can be reduced by the decomposition into rectangles, since only a few parameters have to be used for the calculation.

[0124] Generally speaking, an occupancy map was created by the circle-rectangle decomposition, by means of which a possible collision can be indicated.

[0125] In this case, the occupancy map is monitored by means of sensors, which are arranged on or in the vehicle, in each time segment. The sensors are designed and provided in particular to detect distances.

[0126] The various embodiments with all their features can be combined and exchanged in any manner.

[0127] All features disclosed in the application documents are claimed as essential to the invention, provided that they are, individually or in combination, novel over the prior art.

List of reference signs

[0128] 1 vehicle area [0129] 2 boundary [0130] 3 boundary frame [0131] 4 vehicle area skeleton [0132] 5 first front corner region point [0133] 6 second front corner region point [0134] 7 first rear corner region point [0135] 8 second rear corner region point [0136] 9 front wheelbase point [0137] 10 rear wheelbase point [0138] 11 first lateral corner region point [0139] 12 second lateral corner region point [0140] 13 first circle [0141] 14 second circle [0142] 15 third circle [0143] 16 first skeleton connecting line [0144] 17 maximum area exceedance value [0145] 18 first radius [0146] 19 Y node [0147] 20 first front skeleton connecting line [0148] 21 second front skeleton connecting line [0149] 22 first rear skeleton connecting line [0150] 23 second rear skeleton connecting line [0151] 24 first lateral skeleton connecting line [0152] 25 second lateral skeleton connecting line [0153] 26 vehicle center [0154] 27 first point [0155] 28 lateral skeleton connecting line [0156] 29 vehicle width [0157] 30 first point of intersection [0158] 31 second point of intersection [0159] 32 center of the third circle [0160] 33 fourth circle [0161] 34 center of the fourth circle [0162] 35 third point of intersection [0163] 36 fourth point of intersection [0164] 37 first rear circle [0165] 38 center of the first rear circle [0166] 39 second rear circle [0167] 40 first front circle [0168] 41 second front circle [0169] 42 first lateral circle [0170] 43 second lateral circle