DE102021211711A1 - Driver assistance system and method for controlling a motor vehicle - Google Patents

Abstract

The invention relates to a driver assistance system for a motor vehicle, having a maneuver planning device, a travel trajectory planning device and an interface. The maneuver planning device is designed to generate a list of driving maneuvers based on a roadway model, an object list and driving information. The travel trajectory planning device is designed to calculate a travel trajectory for each driving maneuver in the list of driving maneuvers using a first cost function, with the maneuver planning device being further designed to select a travel trajectory to be traveled on from the travel trajectories calculated by the travel trajectory planning device by evaluating a second cost function. The interface is designed to output the selected travel trajectory.

Description

Driver assistance devices are used for the autonomous or semi-autonomous control of vehicles. These can calculate travel trajectories. A method for driving trajectory planning is from EP 3 291 202 A1 known. The DE 10 2019 102939 A1 discloses a system for motion planning of autonomous vehicles.

In today's driver assistance systems, many decisions are made at the maneuver level, for example, and the road user relevant to the trajectory planner is already selected depending on the maneuver. This means that in the worst case, if the scenario is not well resolved at the maneuver level, the trajectory planner does not know the relevant road user and creates an incorrect driving trajectory. An example is adaptive cruise control, which controls based on the next vehicle in the lane, whereby a motorcycle driving in the right lane is not marked as a relevant object. There is therefore a risk of collision in the event of unexpected motorcycle manoeuvres.

A Model Predictive Planner (MPP) is used to determine an optimal driving trajectory for comfort cases, e.g. steady driving in one lane or system-initiated lane changes, as well as for emergency situations. An MPP contains a vehicle model, information about the capabilities of the actuators and road friction and can therefore calculate the passability of a driving trajectory in advance. In addition, an MPP can optimize the driving trajectory according to several criteria, e.g. B. with regard to speed deviation, lateral acceleration and lateral jerk, or longitudinal acceleration and longitudinal jerk.

Different driving trajectories can be calculated for different driving manoeuvres, e.g. staying in lane, changing lanes, braking to a certain speed and the like.

The movement planning for an autonomous vehicle can be hierarchical, e.g. when planning a route, the entire journey can be planned on the basis of a map. A global planner can plan the next kilometers to reach the destination track of the navigation based on a map. A maneuver planner can plan the next maneuver for the next few seconds based on the perception of the environment and optionally extended by a map. Possible maneuvers include changing lanes or staying in lane. A travel trajectory planner can determine spatial coordinates with a time stamp for the next few seconds, which are passable for the vehicle.

For example, at an intelligent maneuver level, a graph-based search is performed along the road model for a given duration to determine the best maneuver sequence. The travel trajectory can be determined, for example, using a simple spline interpolation.

At a simple maneuver level, a state machine uses heuristics to decide between driving maneuvers, such as staying in lane or changing lanes. The best driving trajectory is determined, for example, by solving an optimization problem.

However, graph-based algorithms for maneuver planning have a high computational effort and cannot guarantee a solution in a fixed runtime for all scenarios.

Intelligent solutions can become very complex at the maneuver planning level with a large number of decision trees, such as rule catalogs or state machines, and thus cannot be handled in the real world. For example, a rule catalog can have no rule for an unexpected scenario, so that there is no adequate reaction.

It is therefore an object of the invention to find an optimal travel trajectory in a simple manner.

This object is achieved by a driver assistance system and a method for controlling a motor vehicle with the features of the independent patent claims.

Further preferred embodiments are the subject matter of the dependent claims.

According to a first aspect, the present invention accordingly creates a driver assistance system for a motor vehicle, with a maneuver planning device, a travel trajectory planning device and an interface. The maneuver planning device is designed to generate a list of driving maneuvers based on a roadway model, an object list and driving information. The travel trajectory planning device is designed to calculate a travel trajectory for each driving maneuver in the list of driving maneuvers using a first cost function, with the maneuver planning device being further designed to select a travel trajectory to be traveled on from the travel trajectories calculated by the travel trajectory planning device by evaluating a second cost function. The interface is designed to output the selected travel trajectory.

According to a second aspect, the present invention provides a method for controlling a motor vehicle. A list of driving maneuvers is generated based on a roadway model, an object list and driving information. A driving trajectory is calculated for each driving maneuver in the list of driving maneuvers using a first cost function. A travel trajectory to be traveled from the calculated travel trajectories is selected by evaluating a second cost function. The motor vehicle is controlled by at least one actuator device according to the selected travel trajectory to be traveled.

Systems that work with rule catalogs for recognized scenarios have the disadvantage that all scenarios to be controlled must be considered during development so that there is a rule for the vehicle reaction.
The invention ensures that an automated vehicle behaves optimally in every scenario, ie there is an optimal solution even for scenarios that were not explicitly considered during development. Even in emergency situations, the safest driving trajectory is always determined.

The method also has the lowest possible complexity in order to find optimal solutions. This is made possible by a division into a travel trajectory planner, which determines the optimal travel trajectory for maneuvers, with a maneuver planner level designed as simply as possible.

The invention is particularly advantageous for all driver assistance system (ADAS) functions, in particular for the degree of automation SAE Level 2 and higher.

According to a further embodiment of the driver assistance system, the interface is designed to output at least one control signal to at least one actuator device for controlling the motor vehicle according to the selected travel trajectory to be traveled.

According to a further embodiment of the driver assistance system, the first cost function depends on at least one comfort parameter, the at least one comfort parameter comprising at least one of a lateral acceleration, a lateral jerk, a longitudinal acceleration and a longitudinal jerk. Accelerations or jerks that are unpleasant for the driver can thereby be ruled out.

According to a further embodiment of the driver assistance system, the travel trajectory planning device is designed to optimize the travel trajectory using the first cost function, taking into account at least one secondary condition, the at least one secondary condition being generated as a function of the roadway model and/or a distance to objects. This means that impermissible travel trajectories can be ruled out.

According to a further embodiment of the driver assistance system, the travel trajectory planning device is designed to optimize the travel trajectory using the first cost function, taking into account a state and/or the estimated future potential of the at least one actuator device. It is thus only possible to determine travel trajectories which can actually be controlled by the actuator device.

According to a further specific embodiment of the driver assistance system, the second cost function depends on at least one driver request from a driver of the motor vehicle. This can be a request to change lanes (e.g. by using the turn signals).

According to a further embodiment of the driver assistance system, the maneuver planning device is designed to create the driving maneuver based on global timetable information. For example, only those maneuvers or travel trajectories can be selected that allow the specified travel destination to be reached.

According to a further embodiment of the driver assistance system, the maneuver planning device is designed to create the driving maneuvers based on cooperative driving strategies and/or to select the driving trajectory to be traveled. As a result, a control of the motor vehicle that is advantageous for all road users can be achieved.

According to a further embodiment of the driver assistance system, the maneuver planning device is designed to select the travel trajectory to be traveled using a collision reduction method. If a collision cannot be avoided, the collision with the least expected damage can be selected.

According to a further specific embodiment, the driver assistance system includes a safety travel trajectory planning device which is designed to determine a safety travel trajectory for safe maneuvering of the motor vehicle. This could be an emergency stop, for example.

According to a further embodiment of the driver assistance system, the object list includes other road users and the prediction of their movement in an area surrounding the motor vehicle. The object list can also include obstacles and the like. The objects and their predicted movements are taken into account when generating the maneuvers and/or trajectories, so that only maneuvers and/or trajectories that do not collide with road users or objects are determined.

According to a further embodiment of the driver assistance system, the driving information includes a current speed and/or acceleration and/or pose of the motor vehicle. This information serves as the starting point for the travel trajectories to be calculated.

According to a further embodiment of the driver assistance system, the driving maneuvers include at least one of a lane change (driver-initiated, system-initiated and optionally also according to the navigation destination), staying in a lane, emergency braking in a current lane of the motor vehicle, emergency avoidance in the current lane of the motor vehicle, emergency avoidance in a lane adjacent to the current lane of the motor vehicle, driving in a lane with road users including cruise control and automatic stopping and driving off, optionally also including driver overtaking maneuvers and lane keeping, collision mitigation, cooperative driving, driving on motorway junctions (including changing lanes), dealing with traffic lights in the City, e.g. driving straight ahead at green traffic lights, dealing with inner-city intersections, e.g. turning at traffic lights.

According to a further embodiment of the driver assistance system, the driving maneuvers include a predefined setting speed. Only travel trajectories that do not exceed the specified setting speed can be calculated there.

According to a further embodiment of the driver assistance system, the first cost function depends on at least one safety parameter. The at least one safety parameter includes a maximum permissible speed, a minimum distance from objects and the like.

The present invention is explained in more detail below with reference to the exemplary embodiments given in the schematic figures of the drawings.

• 1 ein Blockdiagramm eines Fahrerassistenzsystems gemäß einer Ausführungsform der Erfindung; und
• 2 Ein Flussdiagramm eines Verfahrens zum Steuern eines Kraftfahrzeugs gemäß einer Ausführungsform der Erfindung.

Show it:

• 1 a block diagram of a driver assistance system according to an embodiment of the invention; and
• 2 A flow chart of a method for controlling a motor vehicle according to an embodiment of the invention.

Insofar as it makes sense, the configurations and developments described can be combined with one another as desired. Further possible configurations, developments and implementations of the invention also include combinations of features of the invention described above or below with regard to the exemplary embodiments that are not explicitly mentioned.

The accompanying drawings are provided to provide a further understanding of embodiments of the invention. They illustrate embodiments and, together with the description, serve to explain principles and concepts of the invention. Other embodiments and many of the foregoing advantages will become apparent by reference to the drawings. The elements of the drawings are not necessarily shown to scale with respect to one another.

1 shows a block diagram of a driver assistance system with a maneuver planning device 2, a travel trajectory planning device 1 and an interface 9.

The maneuver planning device 2 receives information 10 which includes a roadway model, an object list and driving information. The roadway model includes, for example, dimensions and spatial arrangements of roads, lanes and the like. The object list includes other road users and obstacles in the area surrounding the motor vehicle. The driving information includes, for example, a current speed and a current acceleration of the motor vehicle. The information 10 can have been generated by sensors of the motor vehicle, such as radar sensors, cameras, laser sensors or ultrasonic sensors.

The maneuver planning device 2 generates a list with a large number of driving maneuvers using the information 10 and the information from other devices, such as a maneuver testing device 5, a mode and status manager 6, a global planning device 7 and a collision prevention device 8, which are described below. Depending on the existing lanes and the course of the roadway as well as other road users, the maneuver planning device 2 generates all possible driving maneuvers, such as changing lanes, staying in lane, emergency braking in a current lane of the motor vehicle, emergency evasion in the current lane of the force vehicle and emergency swerving into a lane adjacent to the current lane of the motor vehicle.

The maneuver planning device 2 includes a maneuver status device 21 which generates all the necessary travel trajectory requirements for the travel trajectory planning device 1 . For example, a setting speed is specified.

The list with the driving maneuvers is transmitted to the driving trajectory planning device 1 . The travel trajectory planning device 1 calculates exactly one travel trajectory for each driving maneuver in the list of driving maneuvers by optimizing a first cost function (numerical optimization).

The first cost function can depend on comfort parameters and security parameters. The comfort parameters are used to prevent excessive acceleration or jolting that the driver might find uncomfortable. For this purpose, the comfort parameters can include a lateral acceleration, a lateral jerk, a longitudinal acceleration and a longitudinal jerk. Higher values of these comfort parameters correspond to higher costs in the first cost function, so too large values are avoided.

The travel trajectory planning device 1 can further optimize the first cost function taking into account at least one secondary condition. The at least one secondary condition can be generated as a function of the roadway model. For example, it can be required that a respective driving trajectory lies completely within a specified lane or within specified lanes. Furthermore, a maximum speed can also be transmitted, which is to be maintained along the travel trajectory. Furthermore, a minimum distance to objects can be formulated as a secondary condition.

The travel trajectory planning device 1 can also carry out the optimization of the first cost function taking into account a state of the at least one actuator device 3 . For this purpose, the at least one actuator device 3 can transmit information to the travel trajectory planning device 1 which characterizes the possible control options. For example, an actuator device 3 can transmit an instantaneous steering angle and a maximum permissible steering angle. The travel trajectory planning device 1 only determines those travel trajectories that can also be controlled using this information.

The travel trajectories can include points to be traveled (eg two-dimensional: x, y), curvature parameters and time stamps.

By evaluating a second cost function, the maneuver planning device 2 selects exactly one travel trajectory to be traveled from the travel trajectories calculated by the travel trajectory planning device. The maneuver planning device 2 thus ultimately selects a maneuver which has the lowest costs according to the second cost function. In addition to the costs of the driving trajectory, binary information that is not formulated within the cost function (e.g. collision, leaving the lane) can also be included in the evaluation.

The selected travel trajectory is output via the interface 9, such as a CAN bus or the like. The maneuver planning device 2 can control an external actuator device 3 (such as an electronic braking system). The actuator device 3 can include a general software component for motion control and an actuator control unit. The actuator device 3 can control the vehicle based on a control signal from the maneuver planning device 2, i.e. accelerate, brake or steer, for example. The control signal output to the actuator device 3 controls the actuator device 3 in such a way that the motor vehicle is steered along the selected travel trajectory to be traveled, e.g. by steering torque request, braking torque request and/or axle torque request.

The system also includes a mode and status manager 6, which is informed by the maneuver planning device 2 about the maneuver to be carried out and, conversely, transmits vehicle status information to the maneuver planning device 2, such as actions by the driver (e.g. setting a turn signal), which indicate a driver's wish of the driver, which at the travel trajectories can be taken into account. Additional information may include a degradation state of the motor vehicle. If, for example, the failure of the side sensors is reported, a lane change can no longer be requested.

The information from the mode and status manager 6 can be taken into account by the maneuver planning device 2 for generating the list of driving maneuvers. If the mode and status manager 6 determines, for example, a driver's request “lane change”, the maneuver planning device 2 adds the “lane change” driving maneuver to the list.

The driver assistance system can include other optional components, which gestri chelt are shown and described below. The driver assistance system can include any combination of these components.

A safety travel trajectory planning device 4 can be provided, which includes a safety trajectory calculation device 41 that determines a safety travel trajectory for safe maneuvering of the motor vehicle in the unlikely event that the trajectory of the travel trajectory planner 1 violates safety criteria. The safety driving trajectory can be selected in such a way that predefined criteria are met, such as keeping in the current lane with distance control to the vehicle ahead. Comfort parameters can be disregarded for the safety travel trajectory, so that higher negative accelerations are also permissible. The safety driving trajectory thus serves to maintain a safe driving state.

A safety check device 42 is also provided, which checks the calculated safety travel trajectory and the travel trajectories calculated by the travel trajectory planning device 1 for specified safety criteria, such as freedom from collisions or whether the travel trajectories run within the roadway.

The maneuver planning device 2 can include a travel trajectory list evaluation device 25 which selects the travel trajectory. The list of available travel trajectories consists of the travel trajectories optimized for a maneuver and the safety travel trajectory. The travel trajectory list evaluation device 25 transmits the selected travel trajectory via the interface 9 to the at least one actuator device 3.

A collision prevention device 8 can also be provided, which calculates whether a collision is imminent based on the roadway model, the object list and the driving information. Depending on this evaluation, the collision prevention device 8 recommends a maneuver to the maneuver planning device 2 (e.g. emergency braking or an evasive maneuver) and/or releases higher limits for the maneuver planning device 2, e.g. in longitudinal and lateral acceleration.

The information from the collision prevention device 8 can be taken into account by the maneuver planning device 2 for generating the list of driving maneuvers. If the collision avoidance device 8 determines, for example, that a collision is imminent, the maneuver planning device 2 adds the driving maneuvers “emergency avoidance” and “emergency braking” to the list.

The maneuver planning device 2 can also include an aggregated cost device 24 which determines the aggregated costs of the travel trajectories using the second cost function, with information about possible collisions also being taken into account.

When selecting the maneuver, the maneuver planning device 2 can also include information from a global planning device 7, in which case, for example, the route of a navigation device of the motor vehicle can be included. For example, when selecting the maneuver, distances to the next exit can be taken into account, so that only those maneuvers are proposed that make it possible to drive on the next exit.

A maneuver checking device 5 can also be provided, which uses traffic rules, for example, to check which maneuvers are permissible and transmits a list of the permissible maneuvers to the maneuver planning device 2 .

The maneuver planning device 2 can also include a cooperative driving device 22 so that cooperative driving strategies are taken into account when determining the driving maneuvers and/or when selecting the driving trajectories.

The maneuver planning device 2 can also include a collision reduction device 23 which evaluates the travel trajectories using a collision reduction method, so that the travel trajectory to be traveled is selected taking into account a collision reduction in the event of an impending collision. For example, the driving trajectory with the lowest accident severity can be determined if only colliding driving trajectories remain in the list. Optionally, the driving trajectory with the minimum expected accident severity can also be selected (e.g. emergency braking in the lane, lateral shift to impact with a preceding object with 100% overlap of the front bumper and rear bumper). Time to impact for actuators such as airbag conditioning or passenger positioning can also be maximized.

2 shows a flowchart of a method for controlling a motor vehicle, which can be carried out in particular with the driver assistance system described above.

In a first method step S1, a list of driving maneuvers based on a roadway model, an object list and driving information tion generated. Global timetable information and/or driver requests can be taken into account.

In a second method step S2, a driving trajectory is calculated for each driving maneuver in the list of driving maneuvers using a first cost function. In this case, the first cost function can depend on comfort parameters and safety parameters, with secondary conditions being able to be taken into account during the optimization. In particular, a state of actuator devices 3 of the motor vehicle can be taken into account.

In a third method step S3, a travel trajectory to be driven along from the calculated travel trajectories is selected with the aid of a second cost function. A collision mitigation method can be used for this. The driving trajectory to be traveled can also be selected based on cooperative driving strategies.

In addition, it may be possible for a safety travel trajectory to be determined and for the travel trajectory to be traveled to be selected from the calculated travel trajectories and the safety travel trajectory.

In a fourth method step S4, the motor vehicle is controlled by at least one actuator device 3 according to the selected travel trajectory to be traveled.

Reference List

1

travel trajectory planning device

2

maneuver planning facility

3

actuator device

4

Safety travel trajectory planning device

5

maneuver test facility

6

Mode and State Manager

7

global planning facility

8th

collision avoidance facility

9

interface

10

information

21

Maneuver State Facility

22

Cooperative Driving facility

23

Collision Mitigation Facility

24

Aggregate Cost Setup

25

running trajectory list evaluation means

41

Safety Trajectory Calculator

42

Safety testing facility

S1-S4

process steps

QUOTES INCLUDED IN DESCRIPTION

This list of documents cited by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent Literature Cited

• EP 3291202 A1 [0001]
• DE 102019102939 A1 [0001]

Claims (15)

Driver assistance system for a motor vehicle, with: a maneuver planning device (2) which is designed to generate a list of driving maneuvers based on a roadway model, an object list and driving information; a travel trajectory planning device (1) which is designed to calculate an optimal travel trajectory for each driving maneuver in the list of driving maneuvers using a first cost function, wherein the maneuver planning device (2) is further designed to calculate a travel trajectory to be traveled by evaluating a second cost function to select travel trajectories calculated by the travel trajectory planning device (1); and an interface (9) which is designed to output the selected travel trajectory. driver assistance system claim 1 , wherein the first cost function depends on at least one comfort parameter, wherein the at least one comfort parameter comprises at least one of a lateral acceleration, a lateral jerk, a longitudinal acceleration and a longitudinal jerk. driver assistance system claim 1 or 2 , wherein the travel trajectory planning device (1) is designed to optimize the travel trajectory using the first cost function, taking into account at least one secondary condition, the at least one secondary condition being generated as a function of the roadway model and/or a distance to objects. Driver assistance system according to one of the preceding claims, wherein the travel trajectory planning device (1) is designed to optimize the travel trajectory using the first cost function, taking into account a state and/or the estimated future potential of the at least one actuator device (3). Driver assistance system according to one of the preceding claims, wherein the second cost function depends on at least one driver request of a driver of the motor vehicle. Driver assistance system according to one of the preceding claims, wherein the maneuver planning device (2) is designed to create the driving maneuver based on global timetable information. Driver assistance system according to one of the preceding claims, wherein the maneuver planning device (2) is designed to create the driving maneuvers based on cooperative driving strategies and/or to select the driving trajectory to be traveled. Driver assistance system according to one of the preceding claims, wherein the maneuver planning device (2) is designed to select the travel trajectory to be traveled using a collision reduction method. Driver assistance system according to one of the preceding claims, further having a safety travel trajectory planning device (4) which is designed to determine a safety travel trajectory for safe maneuvering of the motor vehicle. Driver assistance system according to one of the preceding claims, wherein the object list includes other road users and a prediction of their movement in an area surrounding the motor vehicle. Driver assistance system according to one of the preceding claims, wherein the driving information includes a current speed and/or acceleration and/or pose of the motor vehicle. Driver assistance system according to one of the preceding claims, wherein the first cost function depends on at least one safety parameter. Driver assistance system according to one of the preceding claims, wherein the driving maneuvers comprise at least one of a lane change, a lane keeping, emergency braking in a current lane of the motor vehicle, an emergency evasion in the current lane of the motor vehicle and an emergency evasion in a lane adjacent to the current lane of the motor vehicle. Driver assistance system according to one of the preceding claims, wherein the driving maneuvers include a predetermined setting speed. Method for controlling a motor vehicle, with the steps: generating a list of driving maneuvers based on a roadway model, an object list and driving information; calculating a driving trajectory for each driving maneuver of the list of driving maneuvers by optimizing a driving trajectory using a first cost function; selecting a travel trajectory to be traveled from the calculated travel trajectories by evaluating a second cost function; and controlling the motor vehicle according to the selected travel trajectory to be traveled by at least one actuator device (3).

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