GB2513222A

GB2513222A - Method for providing a travel corridor for a vehicle, and driver assistance system

Info

Publication number: GB2513222A
Application number: GB1401875.8A
Authority: GB
Inventors: Thomas Gussner; Stefan Lang
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 2013-02-05
Filing date: 2014-02-04
Publication date: 2014-10-22
Anticipated expiration: 2034-02-04
Also published as: FR3001686B1; GB201401875D0; GB2513222B; DE102013201796A1; FR3001686A1

Abstract

A method for providing a travel corridor for a vehicle 21, wherein a travel corridor, e.g. a clear space, having speed-dependent delimitation, formed as polygonal chains 55, 56, 57, is determined on the basis of captured environment data and a travel corridor having speed-independent delimitation (45, 46, 51, fig 6) is determined from the travel corridor having speed-dependent delimitation 55, 56, 57. The method uses, for example, a camera system 30 and ultrasonic sensors 31 to provide environment data and to determine moving objects 24 in front and/or to a side of the vehicle. The system 30 and sensors 31 also determined an instant when the object 24 is level with the vehicle 21 and a lateral speed of the object 24. Polygonal chains 55, 56, 57 are formed from speed-dependent vertices 41a, 42a, 43a, 44a and represents delimitations, such as pylons (27), of a carriageway. The invention additionally provides a computer program and a, which are set up, in particular, to execute the method.

Description

Description Title

Method for providing a travel corridor for a vehicle, and driver assistance system -

Prior art

The invention relates to a method for providing a travel corridor for a vehicle. The invention additionally provides a computer program and a driver assistance system that can be set up, in particular, to execute the method.

There are various systems that actively support a driver in the lateral guidance of a vehicle. Known in this connection, in particular, are so-called lano keeping systems (LKS) and lane departure warnings (LDW) . Usually, these systems react to lines, which are detected, for example, by means of a camera system.

DE 10 2010 051 492 Al discloses a lane keeping system that, for the purpose of avoiding collisions with other vehicles, additionally has a device for capturing adjacent-vehicle information for an adjacent vehicle on a traffic lane that is next to the traffic lane. A travel course for the so-called ego vehicle is provided in dependence on the adjacent-vehicle information and, if appropriate, the lateral position is regulated. Such adjacent-vehicle information includes, for example, a distance between a detected adjacent vehicle and the ego vehicle, the lateral position and the speed of the detected adjacent vehicle.

DE 10 2005 039 895 Al discloses a system for lane departure warning and/or having a lane keeping function in a motor vehicle, wherein a sensor unit, aligned in the direction of travel, recognizes traffic lanes.

Known from DE 10 2007 027 494 Al is a method for supporting a driver of a vehicle in guiding a vehicle along a traffic lane, a video-based environment capture system, supplemented by a radar system, being used to recognize objects present at the sides. The driver is able to set a reference time interval, a so-called time-to-lateral-collision, in respect of detected vehicles present at the sides.

Disclosure of the invention

In the case of the method for providing a travel corridor for a vehicle, having the features of Claim 1, it is provided that a travel corridor having speed-dependent delimitation is determined on the basis of captured environment daLa, and a travel corridor having speed-independent delimitation is determined for the vehicle from the travel corridor having speed-dependent delimitation.

Advantageously, information relating to both moving and non-moving objects is determined, for example relating to dynamic objects that are overtaken. The method can be applied particularly advantageously in motorway construction sites, where vehicles do not travel exactly in their lane, but are, for example, deliberately diverted.

In this case, explicitly, the lane marking is not required, since this may be incorrect in construction sites.

The travel corridor in this case may be characterized, for example, by the absence of recognized objects or delimitation elements, or of a region that can presumably be passed over by the vehicle without collision.

Preferred embodiments of the invention are characterized by the features of the dependent claims.

Preferably, moving objects present in front of the vehicle and/or to the side of the vehicle are determined. An object recognition system determines objects on captured environment data, and then ascertains whether the respectively determined object is a moving or a static object.

Preferably, further movement quantities of the determined moving objects are determined, namely, their absolute speed, lateral speed and longitudinal speed, these data being used as a basis for determining the corresponding relative speeds in relation to the ego vehicle. The instant at which the object is level with the vehicle can be determined from the relative speed and the determined distance from the moving object. The expression "level with" in this case may denote any reference line that is transverse in relation to the direction of travel of the vehicle, for instance the front axle, the front bumper or a line through a defined environment capture device, for example a front camera.

In the context of the invention, the vehicle whose travel corridor is determined is also referred to as a so-called ego vehicle. Preferably, in the determination of the travel corridor having speed-independent delimitation, movement characteristics of the vehicle are taken into account. Such movement characteristics may be, for example, a direction of movement, speed, lateral speed in respect of its own lane, yaw rate, or may also include limitations for the movement of the vehicle such as, for instance, a maximum yaw rate or a maximally settablo steering angle. Advantageously, in the determination of the movement characteristics of objects present to the side of the vehicle and/or in front of the vehicle, the movement of the ego vehicle is compensated. In particular, the yaw rate of the ego vehicle can be taken into account, this indicating a lateral approach to or moving away from determined objects.

Advantageously, a specified trajectory for the vehicle is determined on the basis of the travel corridor havinq speed-independent delimitation. The specified trajectory can be made available to further driver assistance systems that provide lateral guidance, in particular, for example, to a lane departure warning system or to a lane keeping system.

Advantageously, a clear space is first determined on the basis of a disparity map of a camera system. In the determination of the movement characteristics of objects on the basis of camera data, in particular of objects present to the side of the vehicle and/or in front of the vehicle, Kalman filters, for example, are used. In particular, it may be provided that an object recognition device and an object tracking device are connected on the output side of the camera, in order to make use of information provided by these devices.

Alternatively or additionally, the clear space is dotormined on the basis of distance signals of the ultrasonic sensors. In the determination of the movement characteristic of objects present to the side of the vehicle and/or in front of the vehicle, adapted filtering of the ultrasonic signals, advantageously minimum-filtering, is preferably performed.

Also proposed according to the invention is a computer program, according to which a method described herein is performed when the computer program is executed on a programmable computer device. The computer program may be, for example, a module for implementing a driver assistance system or a sub-system thereof in a vehicle, or an application for driver assistance functions that can be executed on a portable device such as, for instance, a smartphono or a tablet computer. The computer program may be stored on a machine-readable storage medium, for instance on a permanent or rewritable storage medium, or assigned to a computer device, or on a portable unit, for example on a removable CD-ROM, DVD, memory card or a USB stick. Additionally or alternatively, the computer program may be provided on a computer device such as, for instance, on a server, for downloading, e.g. via a data network such as the Internet or a communication connection such as, for instance, a telephone line or a wireless connection.

According to a further aspect, a driver assistance system, which is set up, in particular, to execute one of the methods described herein, comprises a camera system for providing environment data of a vehicle, a unit for determining a travel corridor having speed-dependent delimitation, and a unit for determining a travel corridor having speed-independent delimitation.

The driver assistance system may have furthor environment capture devices, for example radar systems, LIDAR systems or infrared sensors. Particular.1y preferably, the driver assistance system has an ultrasonic system for providing environment data of the vehicle.

Advantages of the invention Provided according to the invention is a lateral guidance assistant that, in particular, can be used advantageously during the overtaking of vehicles in construction sites.

The method and system according to the invention support the driver in lateral guidance in overtaking scenarios, in particular in motorway construction sites. In this case, explicitly, the lane marking is not used, since this may be incorrect in construction sites. The system also reacts appropriately in those situations in which the overtaken vehicle is not travelling within a lane since, particularly in construction sites, a lorry, for example, may occasionally leave a very narrow lane.

Brief description of the drawings

Exemplary embodiments of the invention are represented in the drawings and explained in greater detail in the

description that follows.

In the drawings: Figure 1 shows a schematic representation of components of the method according to the invention, Figure 2 shows a plan view of a situation with an overtaking vehicle, Figure 3 shows a plan view of a situation with a vehicle approaching front behind at an offset, Figure 4 shows a plan view of a situation with an overtaking vehicle, Figure 5 shows a digital conversion of the plan view of the situation with the vehicle from Figure 3 approaching from behind at an offset, Figure 6 shows a front-camera image of the situation represented in Figure 2, Figure 7 shows a front-camera image of the situation represented in Figure 2, at a later point in time, Figure 8 shows a front-camera image of the situatton represented in Figure 3, Figure 9 shows a front-camera image of the situation represented in Figure 4, and Figure 10 shows an ultrasonic signal in the case of overtaking a lorry.

Embodiments of the invention Figure 1 shows a schematic representation of components of the method according to the invention. In first steps 11 and 12, environment captuie devices of the vehicle provide information relating to the environment of the vehicle.

A first environment capture device comprises one or more image sensors, in particular front cameras, rear cameras, BSD cameras ("blind spot detection" cameras), SVA cameras ("side view assistant cameras) and/or SVS cameras ("surround view system" cameras) that can be used, for example, by other driver assistance systems for other purposes. The cameras may be monocular cameras, or cameras of a stereo camera system. An image processing software is used, as is generally known, for evaluation of the camera data.

In optical systems, preferably, there is a video sensor disposed in the front region, preferably centrally, a video sensor in the rear region, likewise preferably centrally, and a respective video sensor on each side of the motor vehicle. The video sensors in the front region and in the rear region may be positioned, for example, in the region of the windscreen1 for example in the mounting of the interior mirror, and in the region of the rear window.

Preferably, video sensors are additionally disposed in the region of the bumpers. It is thereby possible to capture the entire environment around the vehicle.

A second environment capture device comprises an ultrasonic system, a radar system, an infrared system and/or a LIDAR system. An ultrasonic system may comprise a group of ultrasonic sensors that together capture a part of the environment of the vehicle; for example, the ultrasonic sensors in the front region, for capturing a front-side vehicle environment, and/or the ultrasonic sensors in the side region, for capturing a side region of the vehicle, and/or ultrasonic sensors in the rear region, for capturing a rearward environment of the vehicle, may each be assigned to an ultrasonic system. In this case, for example, four to six sensors may be incorporated in a bumper, but generally only a maximum of four sensors, having approximately the same direction of view, are mounted. In particular, in order to capture also the region next to the motor vehicle, sensors whose capture region is to the left and right are positioned in the front bumper. Additionally or alternatively, sensors may also be positioned in the rear bumper in such a manner that they capture a region to the left and right next to the vehicle. Furthermore, the ultrasonic system may also comprise a control device assigned to the respective group, or a common control device, and a signal processing device.

Data and/or measurement values of the environment capture devices are supplied to a processing unit, which, in a further step 13, determines therefrom a time-dependent clear space, with speed information. If a stereo camera system has been set up, in particular to capture a region in front of the ego vehicle, and an ultrasonic system has been set up to capture a region next to the ego vehicle, a clear space, which includes the time as a parameter, is calculated on the basis of the disparity map of the stereo camera and the distance signals of the ultrasonic sensors.

-10 -The time-dependent clear space is represented as a polygonal chain. The node points of the clear space, i.e. the vertices of the polygonal chain, in addition to having the position as an attribute, also have speed as an attribute. If the clear space terminates at a static obstacle such as, for example, a wall, this speed is equal to zero. However, it the clear space terminates at a travelling obstacle such as, for instance, a lorry, then the speed corresponds to that of the travelling object.

From this clear space, in a further step 14, a travel corridor is estimated, which is represented by two polygonal chains that define the right and the left boundary of the travel corridor. For this purpose, the clear space is passed through progressively from the ego vehicle, and all possible paths through the clear space are determined in each case. Then, those paths that cannot be passed through are excluded; this may be because the width of the vehicle exceeds the passage width, or because the necessary curvature of the trajectory would be too great (i.e. the curve would bee too tight) to reach this path at the current speed. The right-side delimitation of the non-excluded path that is furthest to the right then constitutes the right-side delimitation of the travel corridor, and the left-side delimitation of the path furthest to the left then, analogously, constitutes the left-hand delimitation of the travel corridor. In addition to this, a third polygonal chain may be determined, in order to connect the right-side and left-side polygonal chains to each other and to indicate the end of the range of view of the camera. The third polygonal chain constitutes a rear delimitation of the travel corridor.

Moreover, the node points of this travel corridor have -11 -speeds as an attribute, for which reason, in the context of the invention, the travel corridor is also referred to as a speed-dependent corridor.

In a further step 15, a travel corridor having speed-independent dei.imitaUon is determined from the travel corridor having speed-dependent delimitation. i.e. the speed dependence of the travel corridor is removed through prediction of the travel corridor. Travel-corridor limits containing nodes with speeds that are other than zero are recalculated in this case. The corridor resulting from step 15 corresponds to a corridor of a static scenario.

For example, the predicted corridor of a scenario in which a vehicle to the right of and next to the ego vehicle is travelling straight ahead corresponds to that of a scenario in which there is a straight wall extending to the right of and next to the ego vehicle.

In a further step 16, the corridor having speed-independent delimitation is used as a basis for planning a collision-free specified trajectory, and this is used, in a further step 17, for lateral guidance and/or made available to a further driver assistance system, which uses this specified trajectory, for example, for lateral guidance. For example, it may be provided that the calculated specified trajectory is automatically followed on the basis of a steering moment calculated by a controller. The vehicle is thereby steered away from static obstacles and from moving vehicles. Furthermore, it may be provided that the driver, if steering towards moving and static obstacles, perceives a counter-moment on the steering wheel, which increases the subjective perception of safety in confined situations. In -12 -this case, the actual trajectory planning does not distinguish between dynamic and static obstacles.

Represented in Figures 2 to 9 are situations in which the method according to the invention is applied advantageous].y.

Figure 2 shows the case in which an ego vehicle 21 is overtaking another vehicle 24. The driver asststance system is intended to keep the ego vehicle 21 at a distance from the overtaken vehicle 24 by means of corresponding steering interventions, or to build up a perceptible counter-moment if the driver steers in the direction of the vehicle 24 to be overtaken. A predicted travel corridor 50 that achieves this is represented in Figure 6 for the instant represented in Figure 2, and in Figure 7 for a later instant of the overtaking manoeuvre.

During the overtaking manoeuvre, the ego vehicle 21 has a direction of movement 22 on its lane 23. The vehicle 24 to be overtaken, as represented, is on the right-side lane 26 of the road and, for its part, has a direction of movement that is indicated schematically by the arrow 25. On the left side, the road 23 is delimited by a solid carriageway delimitation 27 that, as represented in Figure 6, may be constituted, for example, by a row of pyi.ons 27a. On the right side, the road 23 is likewise delimited by a carriageway delimitation 28. A camera system 30 disposed on the ego vehicle 21 additionally captures lane markings 29 on the road 23 that separate the left-side and right-side lanes from each other. A capture region of the camera system 30 is represented exemplarily here by the reference 32. The ego vehicle 21 additionally has ultrasonic sensors -13 - 31, which have sensing regions 33 that are typically lobe-shaped. In order to sense the region next to the ego vehicle 21, the ultrasonic sensors 31 are positioned in the front bumper, with a sensing region to the left and right.

The sensors in the rear bumper are also positioned such that they sense a region to the left and right next to the ego vehicle 21. The vehicle 24 is partially within the capture region 32 of the camera system, and is also sensed by the front right ultrasonic sensor 31. The distance 34 of the ego vehicle 21 from the overtaken vehicle 24 can be determined on the basis of the captured data.

Figure 3 shows a further situation with the ego vehicle 21 and the vehicle 24 to be overtaken, a so-called offset approach from behind being represented in this case, i.e. the case in which the ego vehicle 21 is travelling with a slight offset 34 towards the vehicle that is to be overtaken. The function guides the driver through a defined steering moment to the left, next to the vehicle 24 to be overtaken. If there is an obstacle such as, for instance, the wall 27, on the left next to the lane, the vehicle is aligned between the wall 27 and the vehicle 24 to be overtaken. The travel corridor predicted by the method according to the invention is represented in Figure 8.

Again, in the case represented, the evaluation of the signals of the camera system 30 and of the ultrasonic system 31 provides information about the lateral distance 34, which, in this case, assumes a negative value and is referred to as an offset. In the case of left-side overtaking, the lateral distance 34 is preferably calculated by relating the right side face 36 of the ego -14 -vehicle 21 to the left aide face 39 of the vehicle 24 to be overtaken. In addition, there is information about a longitudinal distance 35 which, in the case represented, is the distance between the rear face 38 of the vehicle 24 to be overtaken and the front 37 of the ego vehicle 21.

Figure 4 shows a further situation with the ego vehicle 21 and the vehicle 24 to be overtaken, wherein here the vehicle 24 to be overtaken is drifting into the lane 23 of the ego vehicle 21. If a distance 40 becomes correspondingly narrow, then, in order to prevent a lateral collision, it is intended that a steering intervention to the left steers the ego vehicle 21 away from the vehicle 24 that is driving towards the ego vehicle 21. The travel corridor predicted by application of the method according to the invention is represented in Figure 9. The direction of movement 25 of the overtaken vehicle is not parallel to the direction of movement 22 of the ego vehicle 21.

Figure 5 shows a further representation of the situation of offset approach from behind represented in Figure 3. The environment of the ego vehicle 21 is captured by the environment capture units 30, 31, and the objects detected in the environment, in this case the left-side carriageway delimitation 27, the right-side carriageway delimitation 28 and the vehicle 24 to he overtaken, are converted into polygonal chains 55, 56, 57. A first polygonal chain 55 represents the left-side carriageway delimitation 27, and comprises vertices 41. A second polygonal chain 56 represents the right-side carriageway delimitation 28, and comprises vertices 42 that correspond to the right-side carriageway delimitation 28, as well as vertices 43, 44 that are assigned to the vehicle 24 to be overtaken.

-15 -In calculation of the travel corridor, the procedure may be as follows: a specified speed is added, in addition to a specified location, to the vertices 41, 42, 43, 44 of the polygonal chains 55, 56. Then, all vertices having a speed Other than zero are sought. If the number of these vertices exceeds a defined threshold value, a dynamic object is identified, and the corridor must be adapted accordingly. In the exemplary embodiment represented in Figure 5, the vertices 43, 44 assigned to the vehicle 24 to be overtaken have speed values other than zero. The travel corridor for the dynamic obstacle is converted to the travel corridor for a corresponding static obstacle. For this purpose, speed-independent vertices 43a, 44a are calculated, on the basis of a determined absolute speed or on the basis of a determined relative speed in relation to the ego vehicle 21, from the speed-dependent vertices 43, 44. In this case, for the speed-dependent vertices 43, 44, the time at which they will pass the front edge 37 of the vehicle 21 is determined. The vertex 44 having the least time calculated thus is used as a reference point 44 for the subsequent calculation of the speed-independent vertices 43a, 44a. Firstly, the position of the reference point is displaced in the longitudinal and transverse directions. The magnitude of the displacement corresponds to the calculated time at which the reference point 44 passes the front edge 37 of the vehicle 21, multiplied by the longitudinal and transverse speeds, respectively, of the speed-dependent vertex. All further speed-independent vertices 43a, 44a of the speed-independent travel corridor lie on a straight-line segment, which starts in the displaced reference point and terminates at a maximum value in the longitudinal direction, which corresponds, for -16 -example, to the visual range of the sensor. The slope of the straight-line segment corresponds to the ratio of transverse speed and longitudinal speed of the vertices of the speed-dependent travel corridor.

The determined speed-independent vertices 41a, 42a, 43a, 44a ultimately form speed-independent polygonal.. chains 55a, 56a, 57a, which delimit a region that can be passed over by the vehicle without collision, in other words, which delimit the speed-independent travel corridor.

According to a preferred embodiment, it is provided that the driver is allowed, without a disrupting steering intervention, also to cut in just behind the vehicle 24 travelling in front. In this case, the dynamic vertices 43, 44 are firstly searched for the dynamic vertex that has the minimum Euclidean distance from the front edge 37 of the ego vehicle 21, this being the vertex having the reference 44 in the exemplary embodiment represented. For the vertex 44 found thus, the time at which the front edge 37 of the vehicle 21 passes this point is determined. If the ego vehicle 21 is already travelling next to the other vehicle 24, as in the situation represented in Figure 7, this time is equal to zero. If this time exceeds a fixed value, for example a defined time between 0.5 and 5 seconds, preferably between 1 and 3 seconds, particularly preferably 1.5 or 2 seconds, then the corresponding vertex 44, 43 is removed completely. The driver is thereby allowed, without a disrupting steering intervention, also to cut in just behind the vehicle 24 travelling in front.

If the calculated time difference in relation to the selected dynamic vertex is less than the fixed threshold, a new speed-independent vertex 44a is calculated.

-17 -The speed-independent vortex 44a is used as a basis for calculating a halt line, which has its starting point in the newly calculated vertex 44a, and the slope of which is determined on the basis of an evaluation of the lateral speed of the object. The lateral speed can be estimated, for example by means of Kalman filters, from the change in the lateral position. In the prediction step, the ego movement can be switched off as a control variable, in order that changes in the relative lateral speed that are caused by movement of the ego vehicle can be followed more rapidly.

Figure 6 shows the situation represented in Figure 2, as viewed by a front camera of the ego vehicle. On the left side, the carriageway delimitation 27 proves to be a row of pylons 27a, and shown on the right side is the vehicle 24 to be overtaken, which is located in the capture region of the front camera of the ego vehicle. As has been described in connection with Figure 5, polygona' chains 55a, 56a, 57a were determined for the situation represented, which polygonal chains were converted into straight-line segments 45, 46, 51, which delimit a travel corridor 50 of the ego vehicle 21.

The straight-line segments 45, 46 each go through a selected corridor point, for example through the point that has a minimum Euclidian distance from the front edge of the ego vehicle. Since, in the situation represented, the vehicle 24 to be overtaken is already in part next to the ego vehicle 21, the half line 46 in this case starts at the level of the front edge of the ego vehicle.

-18 -Figure 7 shows the same situation as in Figure 6, at a later point in time, in which the overtaken vehicle 24 is fully next to the ego vehicle 21. The vehicle 24 to be overtaken is no longer visible by the video system alone, but is sensed by the ultrasonic sensors. The evaluation of the distance information of the ultrasonic system is used to determine the straight-line. .5egment 46 that delimits the travel corridor 50 of the ego vehicle 21 on the right: sight. The straight-line segments 45, 51 are calculated as described, and delimit the travel corridor SO of the ego vehicle 21 on the left side and to the front.

In order to take account of the movement of the ego vehicle 21, a so-called ego compensation is performed in the filtering of the ultrasonic signals and, according to some embodiments, also in the filtering of the cameral signals.

For this purpose, in the filtering of the ultrasonic signals, the N past distance values are set down in a vector dk = [dk, dkl, ..., dky1]T, wherein k denotes the index of the current time step. y is added to this distance vector, namely dk = dk + Ay with = (ay1, Ay2, ..., wherein Ay = vAtsn w1At.

-19 -In this case, v denotes the ego speed, At denotes the sampling time of the system, and denotes the yaw rate at the sampling instant before j time steps. The lateral variation in the distance in relation to the overtaken vehicle 24 that is caused by the ego vehicle 21 is thus compensated, Then, by minimization over the vector, a distance estimate of the USS signal that is robust against upward outliers can be obtained without the occurrence of an unwanted "lagging" of the signal when the ego vehicle 21 is moving away laterally from the overtaken vehicle. The latter would be manifested in a steering intervention remaining active for too long, which results in a marked bouncing of the ego vehicle 21 away from the overtaken vehicle 24. This is prevented by the described ego compensation.

Figure 8 shows the siLuation of offseL approach from behind represented in Figure 5. Through conversion to speed-independent coordinates, the starting point 47 of the straight line 46 delimiting the travel corridor 50 on the right side, as can be seen from the reference 44a in Figure 5, begins, for example, just behind the vehicle 24 to be overtaken, owing to the detected speed ratios. The straight-line segments 45, 51 are calculated as described, and delimit the travel corridor 50 of the ego vehicle 21 on the left side and to the front. The travel corridor 50 provided for planning of the specified trajectory of the vehicle thus also comprises the location at which the vehicle 24 to be overtaken is present at the instant represented.

In the case of vehicles 24 that steer into the lane 23 of the ego vehicle 21, and that therefore have a corresponding -20 -lateral speed, the predicted travel-corridor limit 46 will project into the lane 23 of the ego vehicle 21, as represented in Figure 9. The straight-line segments 45, 51 are calculated as described, and delimit the travel corridor 50 of the ego vehicle 21 on the left side and to the front. Overtaken vehicles moving laterally away from the ego vehicle 21 have a course analogous to a predicted travel corridor 50, which is directed outwards. The travel corridor is ultimately delimited by a vehicle 24 travelling just next to the ego vehicle, in a manner similar to a wall extending along the lane of the overtaken vehicle.

Figure 10 shows an example of an ultrasonic signal during overtaking of a lorry. Since reflections within the underbody of the lorry reach the ultrasonic sensor in the interim, the lateral distance is overestimated at the marked points 53, 54. The signal jumps in a pronounced manner. In the example represented, the actual distance of the lorry is defined by the first peak value 52, which can be filtered out by application of a minimum operation, taking account of the movement of the ego vehicle. The subsequent procedure corresponds to the procedure explained previously in connection with the key-word "ego compensation", i.e. the values are set down in a vector, corrected with the ego movement, and then the minimum from this vector is used.

The invention is not limited to the exemplary embodiments described here and to the aspects emphasized therein.

Rather, a multiplicity of modifications, which are within the scope of practice of persons skilled in the art, are possible within the scope specified by the claims.