Patent Description:
The present invention also refers to a driving assistance system for a vehicle, which is adapted to perform the above method to perform driving assistance of a vehicle on a single-lane road with passing places.

Furthermore, the present invention refers to a vehicle with an above driving assistance system.

A single-lane road, a single-track road or a one-lane road is a road that in general allows two-way travel under the assumption of few traffic. Hence, the single-lane road is not wide enough in most places to allow two vehicles to pass one another. Even though in some cases, depending on the size of the vehicles, in particular the width of the vehicles, two vehicles can pass each other, this is in general not the case. To accommodate two-way traffic, many single-lane roads, especially those officially designated as such, are provided with passing places, as referred to in the United Kingdom, or pullouts or turnouts, as referred to in the United States, or simply wide spots in the road. The passing places are provided at a border of the road and provide a length width at least corresponding to dimensions of a typical vehicle. Hence, the passing places may be scarcely longer and wider than typical vehicles using the road. The distance between passing places varies considerably, depending on the terrain and the volume of traffic on the road. This single-lane road is common in rural areas.

Based on this road design, when two vehicles try passing each other, one of the vehicles has to safely maneuver to the nearest passing place and allow the other, oncoming vehicle to pass by. Maneuvering a vehicle to a passing place becomes difficult, when the nearest passing place is behind at some distance. A driver has to maneuver his vehicle in a backward direction for a longer distance, until the closest passing place has been reached. This is already a challenge for normal drivers driving normal vehicles, but becomes much worse when driving vehicles with a trailer. This is in particular relevant, when the distance between the passing places is large and/or visibility on the road is limited, so that oncoming traffic can only be detected at a short distance, so that a passing place cannot be chosen ahead to wait for the oncoming traffic.

Assistance systems for assisting drivers in such driving conditions on single-lane roads with passing places are not yet known, so that an improvement is desired. In <CIT> is described how to deal with narrow road using some positioning of the vehicle and an adapted route guidance. In <CIT> is described a method of detecting a clear path in a road of travel for a vehicle utilizing a top-down view classification technique. In <CIT> is described a method for detecting road edges in a road of travel for clear path detection.

It is an object of the present invention to provide a method for driving assistance for a vehicle on a single-lane road with passing places, a driving assistance system for a vehicle, which is adapted to perform the above method, and a vehicle with an above driving assistance system, which enable reliable and efficient driving assistance on single lane roads with passing places.

This object is achieved by the independent claims. Advantageous embodiments are given in the dependent claims.

In particular, the present invention provides a method for driving assistance for a vehicle on a single-lane road with passing places, comprising the steps of capturing consecutive video frames from a camera covering a driving direction of the vehicle, segmenting a road area in the consecutive video frames, detecting a single-lane road scenario based on road segmentation freespace, detecting the passing places along the single-lane road, storing information of passing places along the single-lane road, and upon detection of oncoming traffic, displaying the information regarding the closest passing place to a driver of the vehicle.

The present invention also provides a driving assistance system for a vehicle, which is adapted to perform the above method to perform driving assistance of a vehicle on a single-lane road with passing places.

The present invention further provides a vehicle with an above driving assistance system.

The basic idea of the invention is to enable driving assistance on single lane roads by performing an automatic detection of passing places, which can be stored for passing by other vehicles as required. Based on stored information in respect to the passing places, a maneuver can be started to easily reach the closest passing place. The stored information facilitates to reach the closest passing place and can serve as basis for further actions.

The segmentation of the road area enables a simple means for detecting the passing places. This enables reliable detection of passing places attached to narrow roads. The proposed method is rather simple and eases reverse maneuvering in difficult narrow road conditions. The proposed method is simple and embedded friendly, so that it can be easily implemented.

The consecutive video frames are captured from any kind of suitable camera, e.g. a surround camera, a front camera, or others. The camera can be a regular camera, or a stereo camera, which is arranged in the driving direction. Video frames correspond to single views as provided by the camera.

Segmenting the road area in the consecutive video frames refers to a recognition of the road area and the segmentation of the recognized road area into individual sectors.

The single-lane road scenario refers to a scenario, where a road in general permits two-way travel, but where the road is not wide enough in most places to allow two vehicles to pass one another. Hence, the single-lane roads are provided with passing places, as referred to in the United Kingdom, or pullouts, which enable two vehicles to pass each other. The single-lane road scenario is detected based on the road segmentation and a resulting freespace of the different segments or sectors. In addition, also the passing places are detected along the single-lane road based on the segmentation of the detected road.

The information of the passing places along the single-lane road is e.g. stored in a persistent memory of the vehicle or the driving assistance system. The oncoming traffic is detected in a known way. The driver can review the information, and/or start an action when selecting the displayed information.

According to a modified embodiment of the invention, the method comprises an additional step of performing an autonomous driving maneuver from the current position to the position of the closest passing place. This additional step can be performed also alternatively to the displaying step, i.e. alternatively to displaying the information regarding the closest passing place to a driver of the vehicle upon detection of oncoming traffic. When performing the autonomous driving maneuver from the current position to the position of the closest passing place, the vehicle can be moved by the driving assistance system, until the passing place has been reached. With the assistance system being enabled to perform the autonomous driving maneuver from the current position to the position of the closest passing place, driving on a single-lane road can be highly facilitated for many drivers.

According to a modified embodiment of the invention, the step of performing an autonomous driving maneuver from the current position to the position of the closest passing place comprises continuously displaying at least one information out of a start of the autonomous driving maneuver, a distance to the closest passing place, a velocity of the vehicle, an acceleration of the vehicle, a steering operation of the vehicle. The information can be displayed e.g. on a display of the vehicle, in particular of the driving assistance system, so that vehicle occupants and in particular a driver of the vehicle are continuously informed in respect to a current state of the autonomous driving maneuver from the current position to the position of the closest passing place. This can amongst others be helpful for the driver to prepare to take over control of the vehicle, when the autonomous driving maneuver has stopped.

According to a modified embodiment of the invention, the step of performing an autonomous driving maneuver from the current position to the position of the closest passing place comprises performing in a backward driving direction of the vehicle the steps of capturing consecutive video frames from a camera covering the backward driving direction of the vehicle, segmenting a road area in the consecutive video frames, and detecting the closest passing place along the single-lane road. Hence, the principles discussed above to detect a passing place can be similarly applied to autonomously driving the vehicle backwards to the closest passing place. Once the closest passing place has been reached, the maneuver of the vehicle from the current position to the position of the closest passing place can be stopped. The vehicle can be maneuvered from the single-lane road onto the passing place, so that the oncoming traffic, in particular the oncoming vehicle, can pass the vehicle. The vehicle can be maneuvered onto the passing place either manually by a driver, or autonomously by a driving assistance system.

According to a modified embodiment of the invention, the step of performing an autonomous driving maneuver from the current position to the position of the closest passing place comprises extracting localized map information from a storage and displaying the extracted localized map information to the driver. The localized map information can be provided based on e.g. stored map information, in particular together with received satellite position signals, e.g. GPS signals, which specify a particular position on the localized map. The stored information can comprise odometry information of the vehicle including e.g. a steering wheel angle, a vehicle speed, wheel rotation of one or multiple wheels, in particular wheel tics, or others. Hence, the local map can be generated based on this odometry information. Based on the odometry information, a movement path can be determined, which can be followed in a reverse direction to return to the closest passing place.

According to a modified embodiment of the invention, the step of segmenting a road area in the consecutive video frames comprises performing a luminance based and/or a color based and/or a texture based segmentation algorithm. Hence, the road is identified by means of its distinguishing features compared to the surrounding environment. Such algorithms are known in the Art and need not to be discussed in detail.

According to a modified embodiment of the invention, the step of detecting a single-lane road scenario based on road segmentation freespace comprises additional steps of segmentation of freespace based on road boundaries, and performing a spatial analysis of freespace sectors. Hence, when segmenting the detected road into different sectors, the length of the sectors typically varies with the relative position of a sector. Typically, single-lane roads have lengthy freespace sectors, which correspond to the middle of the road, whereas lateral freespace sectors experience a sharp reduction in length and thereby in freespace, since they are limited by left and right boundaries of the road area. A stable, average freespace sector pattern can be stored in a persistent memory for detection of passing places, which deviate from this average freespace sector pattern. A number of freespace sectors can be chosen suitably, e.g. in a way that each freespace sector covers an angle of <NUM>°, <NUM>°, <NUM>°, <NUM>,<NUM>°, <NUM>° or others.

According to a modified embodiment of the invention, the step of detecting passing places along the single-lane road comprises detection and analysis of lateral road edge boundaries. Left and right boundaries of the road are typically straight and essentially parallel to each other. This can also be represented by an average freespace sector pattern. Hence, when a passing place is provided, the passing place is typically provided with the same material as the road itself, so that a lateral extension of the road area can easily be detected. In other words, the road area extends over the normal ground boundaries. In this case, the respective freespace sector has an increased length in an area of the passing place, which indicates the presence of the passing place.

According to a modified embodiment of the invention, the method comprises an additional step of monitoring a distance to the closest passing place, and the step of displaying the information regarding the closest passing place to a driver of the vehicle comprises displaying a distance to the closest passing place. Based on the distance information, a driver can prepare and decide already in advance in respect to possible actions to take. Hence, even if not yet visible, in case the closest passing place is already far away, it might be beneficial to advance further expecting to find a further passing place ahead, instead of returning the whole way to the closest passing place behind. The distance to the closest passing place can also serve as basis for calculating or estimating a time required to reach the closest passing place, which has been passed previously.

According to a modified embodiment of the invention, the step of monitoring a distance to the closest passing place comprises determining the distance to the closest passing place based on satellite navigation data. Satellite navigation is nowadays available at most location based on different standards, which include GPS, Glonass, Galileo, und Beidou. Satellite navigation data enables identifying a position of the vehicle and, together with a local map, determining a correct way back to the closest passing place.

According to a modified embodiment of the invention, the step of monitoring a distance to the closest passing place comprises additional steps of determining vehicle odometry information, and determining a distance to the closest passing place based on the odometry information. Vehicle odometry information can be used independent from availability of satellite navigation, either availability of respective satellite navigation signals, or availability of a receiver for the satellite navigation signals in the vehicle. The odometry information of the vehicle may comprise e.g. a steering wheel angle, a vehicle speed, wheel rotation of one or multiple wheels, in particular wheel tics, or others. The vehicle odometry information can be used to determine a movement of the vehicle.

According to a modified embodiment of the invention, the method comprises an additional step of determining vehicle odometry information, and determining a vehicle movement from the closest passing place. The odometry information of the vehicle may comprise e.g. a steering wheel angle, a vehicle speed, wheel rotation of one or multiple wheels, in particular wheel tics, or others. Based on the odometry information, a movement path can be determined, which can be followed in a reverse direction to return to the closest passing place. Furthermore, a local map can be generated based on the odometry information.

According to a modified embodiment of the invention, the step of storing information of passing places along the single-lane road comprises determining and storing positions of the passing places, and the step of displaying the information regarding the closest passing place to a driver of the vehicle comprises displaying a current position and driving information between the current position and the position of the closest passing place. This enables provisioning a detailed information in respect to the position of the closest passing place to the driver. The positions can be displayed e.g. as local map, which provides a trajectory from the current position to the closest passing place. According to a modified embodiment of the invention, the method comprises an additional step of providing the stored positions of the passing places to a server. Hence, information regarding located passing places can be shared, e.g. so that map information can be updated. Furthermore, information regarding located passing places can be transmitted to other vehicles in the area, which do not have a proper assistance system, which is able to detect passing places on its own.

These and other aspects of the invention will be apparent from and elucidated with reference to the embodiments described.

<FIG> shows a vehicle <NUM> with a driving assistance system <NUM> according to a first, preferred embodiment of the invention.

The driving assistance system <NUM> comprises a front camera <NUM>, a rear camera <NUM>, and a control unit <NUM>, which is connected to the front camera <NUM> and the rear camera <NUM> via communication bus <NUM>.

Below will be described a method for driving assistance for a vehicle <NUM> on a single-lane road <NUM> with passing places <NUM> according to the first embodiment. The method is performed with the vehicle <NUM> and the driving assistance system <NUM> of the first embodiment. The method will be discussed based on a method flow chart shown in <FIG> and additional <FIG>.

The method starts with step S100, which refers to capturing consecutive video frames from the front camera <NUM>, which cover a driving direction of the vehicle <NUM>. The front camera <NUM> is a regular camera in this embodiment. The video frames correspond to single views as subsequently provided by the front camera <NUM>. Step S100 is performed by a pullout feedback module <NUM> of the control unit <NUM>, as can be seen in <FIG>. The pullout feedback module <NUM> receives the video frames as input <NUM> from the front camera <NUM>.

In step S110, the method continues with a step of segmenting a road area <NUM> in the consecutive video frames. The step is performed in road segmentation module <NUM> of the pullout feedback module <NUM>. Hence, the road area <NUM>, which is the entire area identified as road, including the single-lane road <NUM> and the passing place <NUM>, is detected. The road area <NUM> is shown e.g. in <FIG> as delimited by road boundary <NUM>. According to step S110, first the road area <NUM> is recognized in the consecutive video frames. Hence, the road area is identified by means of its distinguishing features compared to the surrounding environment. A luminance based and/or a color based and/or a texture based segmentation algorithm is performed. Such algorithms are known in the Art and need not to be discussed in detail. Then, the road area <NUM> is segmented into multiple freespace sectors <NUM>. A number of freespace sectors <NUM> can be chosen suitably, e.g. in a way that each freespace sector <NUM> covers an angle of <NUM>°, as can be seen in <FIG>. Step S110 is performed by road segmentation module <NUM> of the pullout feedback module <NUM>, as can be seen in <FIG>.

In step S120, a single-lane road scenario is detected based on road segmentation freespace of the freespace sectors <NUM>. The single-lane road scenario refers to a scenario as mentioned above, where the single-lane road <NUM> in general permits two-way travel, but where the single-lane road <NUM> is not wide enough in most places to allow two vehicles <NUM> to pass one another. Hence, the single-lane roads <NUM> are provided with passing places <NUM>, as referred to in the United Kingdom, or pullouts, which enable two vehicles <NUM> to pass each other. The single-lane road scenario is detected based on the above road segmentation and a resulting freespace of the different freespace sectors <NUM>. The segmentation of the freespace is based on the road boundaries <NUM>, which define the road area <NUM>.

In addition, also the passing places <NUM> are detected along the single-lane road <NUM> based on the segmentation of the detected road. Accordingly, a spatial analysis of the freespace sectors <NUM> is performed. The length of the freespace sectors <NUM> typically varies with the relative position of a freespace sector <NUM>. The single-lane road <NUM> has lengthy freespace sectors <NUM>, which correspond to the middle of the single-lane road <NUM>, whereas lateral freespace sectors <NUM> experience a sharp reduction in length and thereby in freespace, since they are limited by left and right boundaries of the road area <NUM>. A stable, average freespace sector pattern, which defines average boundaries <NUM> as shown in <FIG>, is stored in a persistent memory <NUM> for detection of passing places <NUM>, which deviate from this average freespace sector pattern and the average boundaries <NUM>.

Step S120 is performed by narrow road & road edge detection module <NUM> of the control unit <NUM>, as can be seen in <FIG>.

Step S130 refers to detecting the passing places <NUM> along the single-lane road <NUM>, which comprises a detection and analysis of lateral road edge boundaries <NUM>. Left and right boundaries of the single-lane road <NUM> are typically straight and essentially parallel to each other. This is represented by the average freespace sector pattern. Hence, when a passing place <NUM> is provided, the passing place <NUM> is typically provided with the same material as the single-lane road <NUM> itself, so that a lateral extension of the road area <NUM> appears. Accordingly, the freespace of the lateral freespace sectors <NUM> is essentially bigger than for the average freespace sector pattern. In this case, the respective freespace sector <NUM> has an increased length in an area of the passing place <NUM>. Step S130 is performed by pullout detection module <NUM> of the control unit <NUM>, as can be seen in <FIG>.

Step S140 refers to storing information of the detected passing places <NUM> along the single-lane road <NUM>. The information of the passing places <NUM> is stored in the persistent memory <NUM> of the vehicle <NUM> or the driving assistance system <NUM>. Storing the information of passing places <NUM> comprises determining and storing positions of the passing places <NUM>. The information of a closest passing place <NUM> out of the stored passing places <NUM> is displayed to a driver of the vehicle <NUM>. Displaying the information comprises displaying a current position and driving information between the current position and the position of the closest passing place <NUM>. The positions can be displayed e.g. as local map, which provides a trajectory from the current position to the closest passing place <NUM>. Step S140 is performed by localization and mapping module <NUM> of the control unit <NUM>, as can be seen in <FIG>.

According to step S150, a distance to the closest passing place <NUM> is continuously monitored and displayed, and the step of displaying the information regarding the closest passing place <NUM> to a driver of the vehicle <NUM> comprises displaying a distance to the closest passing place <NUM>. The distance to the closest passing place <NUM> is determined based on satellite navigation data, which are GPS data in this embodiment, together with map information. Additionally, the distance to the closest passing place <NUM> is monitored based on the determined vehicle odometry information, which comprises a steering wheel angle, a vehicle speed, and wheel rotation of one or multiple wheels, in particular wheel tics. Hence, the method comprises an additional step of determining vehicle odometry information, as specified above. Furthermore, a vehicle movement is determined from the closest passing place <NUM> onwards to the present location. Based on the odometry information, a movement path is determined, which can be followed in a reverse direction to return to the closest passing place <NUM>. Still further, a local map is generated based on the odometry information. Monitoring and displaying the information is performed by localization and mapping module <NUM> of the control unit <NUM>, as can be seen in <FIG>, which receives the odometry information from vehicle odometry module <NUM>. Data is output to display output module <NUM>.

In step S160, upon detection of oncoming traffic, at least part of the stored information regarding the closest passing place <NUM> is displayed to a driver of the vehicle <NUM>. Also here, the data is output to display output module <NUM>. The driver can confirm to start subsequent step S170.

According to step S170, an autonomous driving maneuver from the current position to the position of the closest passing place <NUM> is performed. When performing the autonomous driving maneuver, the vehicle <NUM> is moved by the driving assistance system <NUM>, until the closest passing place <NUM> has been reached. Step S170 is started by a driver operation, e.g. the driver starts the autonomous driving maneuver by acknowledging the information displayed by the driving assistance system <NUM>. The autonomous driving maneuver from the current position to the position of the closest passing place <NUM> is performed by an auto pullout maneuver system <NUM> of the control unit <NUM>, which can be seen in <FIG>. Some modules of the auto pullout maneuver system <NUM> are identical to those of the pullout feedback module <NUM>, and are not discussed again in detail. Hence, reference numerals for such modules have not been changed.

Accordingly, input <NUM> with captured consecutive video frames is received from the rear camera <NUM>, since the vehicle <NUM> has to move backwards to the closest passing place <NUM>. The input <NUM> is provided to and processed by the road segmentation module <NUM>, the narrow road & road edge detection module <NUM>, and the pullout detection module <NUM>, as discussed above in respect to the pullout feedback module <NUM>.

When the closest passing place <NUM> has been reached, the maneuver of the vehicle <NUM> to the position of the closest passing place <NUM> is stopped, and the vehicle <NUM> is maneuvered from the single-lane road <NUM> onto the passing place <NUM>, so that the oncoming traffic can pass the vehicle <NUM>. The vehicle <NUM> is maneuvered onto the passing place <NUM> autonomously by the driving assistance system <NUM> by pullout maneuver module <NUM>, which receives odometry information from vehicle odometry <NUM>. The pullout maneuver module <NUM> controls the vehicle <NUM> via output module <NUM> break, accelerate, and to steer the vehicle <NUM> by changing its direction.

While the autonomous driving maneuver from the current position to the position of the closest passing place <NUM> is performed, localized map information is extracted from the persistent memory module <NUM> and displayed to the driver. The localized map information is provided based on e.g. stored map information, in particular together with received satellite position signals, e.g. GPS signals, which specify a particular position on the localized map. The stored further comprise odometry information of the vehicle <NUM>. Hence, the local map can be generated under additional consideration of this odometry information. This is performed in extract stored localized map and distance update module <NUM>. Information display is provided via display module <NUM>.

Furthermore, during the maneuver performed in step S170, display module <NUM> performs a continuous displaying operation of a start of the autonomous driving maneuver, a remaining distance to the closest passing place <NUM>, a velocity of the vehicle <NUM>, an acceleration of the vehicle <NUM>, and a steering operation of the vehicle <NUM>. The information is displayed on a screen of the vehicle <NUM>, in particular of the driving assistance system <NUM>, even more particular of the display module <NUM>, so that vehicle occupants, and in particular a driver of the vehicle <NUM>, are continuously informed in respect to a current state of the autonomous driving maneuver.

Claim 1:
Method for driving assistance for a vehicle (<NUM>) on a single-lane road (<NUM>) with passing places (<NUM>), comprising the steps of
capturing (S100) consecutive video frames from a camera (<NUM>) covering a driving direction of the vehicle (<NUM>),
segmenting (S110) a road area (<NUM>) in the consecutive video frames into multiple freespace sectors (<NUM>),
detecting (S120) a single-lane road scenario based on road segmentation freespace of the freespace sectors (<NUM>),
detecting (S130) the passing places (<NUM>) along the single-lane road (<NUM>),
storing (S140) information of passing places along the single-lane road, and
upon detection of oncoming traffic, displaying the information regarding the closest passing place (<NUM>) to a driver of the vehicle (<NUM>) wherein
the step of detecting a single-lane road scenario based on road segmentation freespace comprises additional steps of
segmentation of the freespace sectors (<NUM>) based on road boundaries (<NUM>), and performing a spatial analysis of the freespace sectors (<NUM>)
wherein the step of detecting passing places (<NUM>) along the single-lane road (<NUM>) comprises detection and analysis of lateral road edge boundaries (<NUM>) and
detection of the passing places (<NUM>), which deviate from average freespace sector pattern, which defines average boundaries (<NUM>), stored in a persistent memory (<NUM>).