Collision avoidance system for a motor vehicle, assistance system for a motor vehicle and motor vehicle

Abstract

The invention relates to a method for collision avoidance for a motor vehicle (200), comprising the steps: - Initiating an automated evasive maneuver (10) of the motor vehicle (200) with at least one initial evasive movement (11), - Continuing the automated evasive maneuver (10) with at least one further evasive movement (12) when a time window (Z) for correcting the automated evasive maneuver (10) has elapsed, wherein the at least one further evasive movement (12) is different from the at least one first evasive movement (11), and an assistance system (100) for a motor vehicle (200) and a motor vehicle (200).

Description

[0001] The invention relates to a method for collision avoidance for a motor vehicle, an assistance system for a motor vehicle and a motor vehicle.

[0002] Driver assistance systems are used in motor vehicles such as cars or trucks to provide sensory and actuator support to the driver in road traffic, or even to replace the driver in fully automated driving (e.g., SAE Level 5). In particular, these systems can be used to avoid collisions with obstacles and thus increase road safety.

[0003] From DE 10 2018 221 241 A1 a driver assistance system for a motor vehicle, a corresponding motor vehicle with such a driver assistance system and a method for operating such a motor vehicle is known.

[0004] German patent DE 10 2008 045 481 A1 discloses a method for triggering an automatic emergency braking maneuver of a vehicle to prevent a collision with a vehicle ahead or to mitigate the consequences of a collision, whereby a driver warning is triggered when at least one predefined warning condition is met. A warning condition specifies that, based on the vehicle's current driving situation (taking into account a determined acceleration of the vehicle and / or a determined relative acceleration between the vehicle and the vehicle ahead) and a predefined emergency braking deceleration, the automatic emergency braking maneuver is to be triggered after a predefined warning time has elapsed. The aim is to achieve a predefined target relative speed and / or a predefined target safety distance between the vehicle and the vehicle ahead upon completion of the automatic emergency braking maneuver.Furthermore, a driver warning, perceptible to the driver of the vehicle, is issued in the form of a partial braking process with a predetermined, continuously increasing partial braking deceleration.

[0005] From DE 10 2009 020 649 A1, a method for collision avoidance by a vehicle swerving to avoid an obstacle is known, wherein, in the event of an impending collision, several possible evasive trajectories are determined and time interval limits are assigned to the evasive trajectories. These time interval limits represent the time distance to the obstacle at which an evasive maneuver must be initiated at the latest in accordance with the respective trajectory to avoid the collision. Upon reaching one or more of the time interval limits, a warning perceptible to the driver of the vehicle is triggered. Preferably, upon reaching a time interval limit, an automatic evasive maneuver is initiated along an evasive trajectory, provided that collision avoidance by emergency braking is no longer possible.

[0006] From DE 10 2008 016 377 A1, a method for operating a motor vehicle is known, comprising means for detecting the position and speed of an obstacle relative to the motor vehicle in a forward environment of the motor vehicle, means for detecting the steering activity of a vehicle within the motor vehicle, and means for influencing a steering torque of the motor vehicle. Upon detection of an imminent collision between the motor vehicle and the obstacle that would be unavoidable by braking, and then when the driver of the motor vehicle initiates an evasive maneuver by steering, the steering torque is adjusted such that evasive action along a determined trajectory is supported, provided that the collision can be avoided by such evasive action.

[0007] The technical problem is to create a collision avoidance procedure for a motor vehicle, an assistance system for a motor vehicle, and a motor vehicle that can increase road safety.

[0008] The solution to the technical problem is provided by the articles with the features of the independent claims. Further advantageous embodiments of the invention are described in the dependent claims.

[0009] A collision avoidance procedure for a motor vehicle is proposed, comprising the following steps: - Initiating an automated evasive maneuver of the motor vehicle with at least one initial evasive movement, - Continuing the automated evasive maneuver with at least one further evasive movement when a time window for correcting the automated evasive maneuver has elapsed, wherein the at least one further evasive movement is different from the at least one first evasive movement.

[0010] The proposed method provides an opportunity to correct the automated evasive maneuver during the initial evasive action. This allows the initiated evasive maneuver to be aborted or modified. Simultaneously, the evasive maneuver is already executed, thus optimizing the use of available time for collision avoidance. After the time window expires, the initiated evasive maneuver is automatically continued with a subsequent evasive action, which differs from the first, for example, in its driving dynamics. This effectively complements the initial evasive action, and the remaining time after the time window expires is efficiently used for automated vehicle maneuvering.For example, the vehicle can be maneuvered within a dynamically limited range by the further evasive maneuver, a range that was not reached in the first evasive maneuver, thus avoiding surprising the driver with a sudden, abrupt initial maneuver. This increases road safety.

[0011] Initiating an evasive maneuver can occur, for example, as a reaction to a sensor-detected collision risk. The first evasive movement can be executed as soon as the detected collision risk exceeds a critical risk threshold. The evasive maneuver can be initiated, for example, by an initial control command.

[0012] The initial evasive maneuver can, for example, include or be designed as an initial deceleration of the vehicle. This initial maneuver reduces the initially detected collision risk. The driver might perceive this initial deceleration as, for example, a slight, automated braking action. Naturally, the initial evasive maneuver can also include, cumulatively or alternatively, an initial steering movement that gently maneuvers the vehicle out of a collision zone. The initial evasive maneuver can be executed without a visual or audible warning. The driver can be alerted to the detected collision risk by the initial evasive maneuver – thus, it serves as a warning. The initial control command can, for example, include parameters for setting the initial evasive maneuver. The initial evasive maneuver can be executed, for example, using the aforementioned actuator. The parameters can, for example...Parameterize an actuator force or actuator displacement.

[0013] The correction window can begin when the automated evasive maneuver is initiated. This window can be preset to, for example, one second. Within this window, the driver or the assistance system can influence the initiated evasive maneuver. For instance, the maneuver can be aborted or at least suspended. This allows, for example, an unnecessary evasive maneuver to be stopped or a necessary one to be readjusted. Naturally, the evasive maneuver can also be confirmed within the window, for example, by the driver. Confirmation of the evasive maneuver can then be considered to have expired, regardless of the initially preset time. The time window can be monitored, for example, using the aforementioned control unit.

[0014] The automated evasive maneuver can be continued, for example, immediately after the time window expires. The maneuver can be continued, for example, by a further control command. This further control command can include parameters for setting the actuator's subsequent evasive movement. The subsequent evasive movement can then be executed, for example, using the aforementioned actuator.

[0015] The subsequent evasive maneuver involves a further steering input. This subsequent maneuver significantly reduces the remaining collision risk after the initial evasive maneuver. For example, the subsequent evasive maneuver can abruptly maneuver the vehicle out of a collision zone along an evasive path. The subsequent evasive maneuver can exhibit higher lateral acceleration than the initial maneuver, with the vehicle being maneuvered out of the collision zone, for example, at the limits of its driving dynamics. Of course, the subsequent evasive maneuver can also differ from the initial maneuver in that it involves lower lateral acceleration, for example, if the collision risk has already been sufficiently reduced or even eliminated by the initial maneuver. The subsequent evasive maneuver can cumulatively include further deceleration, which slows the vehicle. For example, the subsequent evasive maneuver can...to be carried out using the aforementioned actuator.

[0016] The at least one initial evasive maneuver comprises a first steering angle profile, and the at least one subsequent evasive maneuver comprises a further steering angle profile, the latter having a larger absolute value than the initial steering angle profile. In this way, maximum steering angle is only achieved through the subsequent evasive maneuver. The magnitude of the steering angle can be specified, for example, in radians. The respective steering angle profile can be linear, for example. The respective steering angle profile can be set, for example, by parameters. In particular, the initial steering angle profile can have at least one initial slope, and the subsequent steering angle profile can have at least one further slope, the latter being greater than the initial slope. In this way, for example,The steering angle speed is increased during the further evasive maneuver compared to the first evasive maneuver.

[0017] The transition from the first evasive maneuver to the subsequent one is indistinguishable. Due to this indistinguishable transition, the driver can perceive the continuation of the evasive maneuver haptically, for example, as a jerk in the steering wheel. This indistinguishable transition can manifest itself, for example, as a change in gradient or a kink between the previously described initial steering angle profile and the subsequent one. The indistinguishable transition can also appear, for example, as a jump in steering angle velocity between the two evasive maneuvers.

[0018] Furthermore, at least one additional evasive maneuver comprises several sequences, in which at least one sequence involves a decrease in the steering angle and at least one subsequent sequence involves an increase in the steering angle, with the first sequence being shorter in time than the second. In this way, the vehicle's dynamic limits can be exploited more effectively during the subsequent evasive maneuver. This is because a decrease in the steering angle is associated with a lower risk of the vehicle skidding than an increase in the steering angle and can therefore be executed more quickly.

[0019] Furthermore, an assistance system for a motor vehicle is proposed, wherein the assistance system is configured to execute a method according to an embodiment described in this disclosure.

[0020] Furthermore, a motor vehicle comprising at least one assistance system according to an embodiment described in this disclosure is proposed. The motor vehicle can be, for example, a passenger car or a truck.

[0021] Naturally, the technical effects and advantages mentioned below for the procedure also apply to the assistance system and the motor vehicle.

[0022] The assistance system may include a detection device for identifying a collision risk. The detection device may, for example, be a forward-facing camera with a microcontroller. The assistance system may, for example, include a control unit for generating control commands. The control unit may, for example, be a microcontroller. The assistance system may, for example, include an actuator for executing evasive maneuvers. The actuator may, for example, be a hydraulically driven brake and / or steering actuator.

[0023] In one embodiment, the at least one further evasive maneuver is set such that the vehicle passes through at least one clothoid segment. This makes the evasive maneuver particularly stable, as a smooth, progressive change in steering angle occurs during each clothoid segment. This avoids abrupt changes in lateral forces and reduces the risk of the vehicle skidding. During the evasive maneuver, the vehicle can travel a distance that corresponds at least partially to a clothoid. Part of this distance can form a clothoid segment. Alternatively or cumulatively, the at least one initial evasive maneuver can, of course, be set such that the vehicle passes through at least one clothoid segment. This can reduce the risk of the vehicle skidding during the initial evasive maneuver.

[0024] In one embodiment, the time window is determined based on a detected collision risk. This allows the duration of the time window to be adapted to the detected collision risk, so that, for example, the time window can be shorter for a high collision risk than for a low collision risk, and vice versa. The collision risk can be expressed, for example, as a percentage, where nearly 0% indicates a very low collision risk and nearly 100% a very high collision risk.

[0025] In one embodiment, the time window is determined based on driver data. This allows the duration of the time window to be adapted to the driver's current driving behavior. For example, the time window can be longer if the driver data indicates driver fatigue, or shorter if the data indicates driver alertness. Obtaining driver data is a familiar process for those skilled in the art. The assistance system can, for example, include a device for acquiring driver data. This device can be, for example, a camera with a microcontroller focused on the driver.

[0026] In one embodiment, at least one further evasive maneuver is set within the time window. This allows the time window to be used to increase the accuracy and safety of the initiated evasive maneuver. For example, the most suitable further evasive maneuver can be determined during the time window. The further evasive maneuver can be set depending on a remaining collision risk. The remaining collision risk can, for example, be detected during the time window. The previously described detection device of the assistance system can be configured to detect the remaining collision risk during the time window. The further evasive maneuver can, for example, be set by parameters that reduce the detected remaining collision risk. The parameters of the further evasive maneuver that reduce the remaining collision risk can, for example,be known beforehand from experiments or simulations.

[0027] In one embodiment, the at least one further evasive maneuver is set such that a maximum lateral force is achieved during the maneuver without exceeding a friction limit between the vehicle and the road surface. In this way, the vehicle does not lose traction or skid during the further evasive maneuver, but can still be driven automatically at the limits of vehicle dynamics. The maximum lateral force refers in particular to the maximum physically permissible force in a lateral direction—for example, perpendicular to the vehicle's direction of travel and perpendicular to gravity—without the vehicle losing traction on the road surface. The friction limit refers in particular to the ratio of the maximum lateral force to a normal force. The normal force is, for example, the force of gravity acting on the vehicle. The maximum lateral force and normal force act during the further evasive maneuver.For example, between the tires of the vehicle and the road surface. The friction limit can be known in advance, for example, as a coefficient of friction between the road surface and the vehicle. The coefficient of friction can be detected cumulatively or alternatively by sensors. The assistance system can, for example, include a sensor device for detecting the coefficient of friction. In particular, the subsequent evasive maneuver can be adjusted, for example, by parameters such that the ratio of a lateral force to a normal force during the evasive maneuver does not fall below the friction limit by more than a known deviation, thus achieving the maximum lateral force. The deviation can, for example, be 10% of the coefficient of friction. The parameters for adjusting the subsequent evasive maneuver can be known in advance, for example, from tests or simulations.

[0028] The invention is explained in more detail using exemplary embodiments. The figures show: Fig. 1. A schematic representation of an automated evasive maneuver, Fig. 2 a schematic diagram of an alternative route perpendicular to a carriageway, Fig. 3 a schematic diagram of a steering angle over a distance of the evasive maneuver and Fig. 4 a schematic diagram of a steering angle velocity over time.

[0029] In the following, identical reference symbols denote elements with the same technical characteristics.

[0030] Fig. Figure 1 shows a schematic representation of an evasive maneuver 10 from a top view.

[0031] In Fig. Figure 1 shows a motor vehicle 200, designed as a passenger car, traveling at approximately 50 km / h on lane 51 of a roadway 50. The roadway 50 has two lanes 51 and 52, which are divided into Fig. The lanes are separated by a dashed line. In lane 51, in front of motor vehicle 200 in direction X, there is an obstacle 300. The obstacle 300 is, for example, a broken-down car leaning at an angle in lane 51. A detection device (not shown) of motor vehicle 200 can detect that there is a risk of collision due to the obstacle 300, which can be reduced, or even eliminated, by the evasive maneuver 10 into, for example, the adjacent lane 52.

[0032] The motor vehicle 200 includes an assistance system 100, which is designed to execute a collision avoidance procedure. The aforementioned detection device may be part of the assistance system 100. The procedure executed by the assistance system 100 comprises at least the following steps: In one step, the evasive maneuver 10 is initiated automatically with an initial evasive movement 11, e.g., in response to the detected collision risk. Simultaneously with the initiation of the evasive maneuver 10, a time window Z begins for correcting the automated evasive maneuver 10.

[0033] In Fig. 1 is a route traveled by the motor vehicle 200 during the time window Z in the direction of travel X, indicated by a double arrow. A time start T0 and a time end T1 of the time window Z are shown in Fig. 1 each marked by a vertical dashed line, which corresponds to a location where the motor vehicle 200 is situated in the direction of travel X at times T0, T1. The distance between these vertical lines is given in Fig. 1 is indicated by the reference point of the time window Z.

[0034] Within the time window Z, the evasive maneuver 10 can be corrected, for example, by the driver of the vehicle 200 or by the assistance system 100. In this way, for example, an evasive maneuver 10 that is unnecessary from the driver's perspective can be aborted, or the evasive maneuver 10 can be stopped by the driver or the assistance system 100.

[0035] The time window Z can be determined depending on the detected collision risk. If the detected collision risk is, for example, greater than a known risk value, the time window Z can be shortened from a preset duration of one second to, for example, half a second. This allows the evasive maneuver 10 to be continued as quickly as possible with a further evasive movement 12.

[0036] Alternatively or cumulatively, the time window Z can be determined based on driver data. The assistance system 100 can include a data acquisition device (not shown) for determining driver data, which can, for example, indicate the driver's current level of fatigue. If the driver's current level of fatigue is, for example, above a known fatigue threshold, the time window Z can be extended compared to the preset duration to give the driver more time to correct the evasive maneuver 10. However, extending the time window Z may be precluded if the detected collision risk exceeds the aforementioned risk value.

[0037] In a further step, the automated evasive maneuver of the procedure continues with the further evasive movement 12 when the time window Z has expired (i.e. at time T1).

[0038] The subsequent evasive maneuver 12 can be adjusted, for example, by parameters of an actuator force of an actuator (not shown) of the vehicle 200, such that the subsequent evasive maneuver 12 achieves a maximum lateral force (in the lateral direction Y), allowing the vehicle 200 to be maneuvered out of lane 51 in a driving dynamics limit area without skidding. The automated evasive maneuver 10 is successfully completed, for example, when the vehicle 200 has finished the lane change and is driving stably in lane 52, i.e., when no lateral force is acting on the vehicle 200.

[0039] Fig. Figure 2 shows a schematic diagram of an evasive route (in meters) in a transverse direction Y along a driving path (in meters) of a motor vehicle 200 along a carriageway direction X. The course of the evasive route corresponds to the one shown in Figure 2. Fig. 1. Evasive maneuver shown 10. In Fig. 2. It is also apparent that the evasive route in the transverse direction Y is approximately 1.4 meters and the evasive maneuver 10 along the roadway direction X is approximately 30 meters.

[0040] Furthermore, in Fig. 2. It can be seen that the further evasive maneuver 12 comprises several clothoid segments K1, ..., K4, whereby the evasive maneuver 12 is segmented (indicated by double arrows). In each clothoid segment K1, ..., K4, there is a uniform, progressive change in the lateral force acting on the motor vehicle 200. This increases the stability of the motor vehicle 200 during the evasive maneuver 10, since no abrupt change in the lateral force occurs during a clothoid segment K1, ..., K4. This will be explained in more detail below.

[0041] Fig. Figure 3 shows a schematic diagram of a steering angle L versus a path length of the evasive maneuver 10. The path length can be, for example, the arc length of the Fig. 1 and Fig. The 2 evasive maneuvers shown correspond to 10.

[0042] A first evasive movement 11 differs in Fig. 3 of a further evasive movement 12 by the fact that the first evasive movement 11 includes a first steering angle profile L1 and the further evasive movement 12 includes a different further steering angle profile L2.

[0043] During the first evasive maneuver 11, the steering angle L increases linearly from a zero position (corresponding, for example, to driving straight ahead at time T0) with an initial slope. At the end T1 of the time window Z, the steering angle L therefore reaches a value L1max.

[0044] At the end of time window T1 Z, the evasive maneuver 10 continues with the further evasive movement 12. The further evasive movement 12 comprises several sequences S1, ..., S4 (in Fig. 3 marked by double arrows). Each of the in Fig. The 3 sequences shown S1, ..., S4 correspond to an associated clothoid segment K1, ..., K4 (cf. Fig. 2) This is particularly evident from the fact that the steering angle L changes linearly within the sequences S1, ..., S4, thereby ensuring that a lateral force acting on the motor vehicle 200 changes uniformly in each sequence S1, ..., S4, i.e. proportionally to the distance traveled.

[0045] In the first sequence S1, the steering angle L increases from the value L1max with a further incline. The transition from the first evasive maneuver 11 to the subsequent evasive maneuver 12 is indistinguishable, so the driver experiences, for example, a jolt in the lateral direction Y, which haptically conveys the continuation of the automated evasive maneuver 10 with the further evasive maneuver 12. The passage of time Z can thus be communicated to the driver without an additional warning.

[0046] At the end of the first sequence S1, the steering angle L assumes a steering angle L21max, which corresponds, for example, to a maximum counterclockwise steering input. The subsequent steering angle profile L2 thus exhibits a larger absolute value than the initial steering angle profile L1. As a result, the maximum steering input is only reached after the time window Z has elapsed, due to the further evasive maneuver 12.

[0047] In a further sequence S2, the steering angle L decreases linearly from the steering angle L21max until the steering wheel returns to its neutral position. In the subsequent sequence S3, the steering angle L again increases linearly from its neutral position until a steering angle L22max is reached, which corresponds, for example, to the maximum clockwise steering angle of vehicle 200. In the following sequence S4, the steering angle L is changed so that the steering wheel once again returns to its neutral position and the evasive maneuver 10 is completed.

[0048] Fig. Figure 4 shows a schematic diagram of a steering angular velocity V over time in seconds. The depicted course of the steering angular velocity V can be compared to the values ​​shown in the Fig. 1, Fig. 2 and Fig. The 3 scenarios described correspond to each other.

[0049] Out of Fig. Figure 4 shows that the steering angular velocity V during the first evasive movement 11 of the evasive maneuver 10 is positive. The steering velocity V of the first evasive movement 11 can therefore correspond to a gentle steering input. For example, a steering wheel (not shown) of the motor vehicle 200 is turned uniformly counterclockwise by means of an actuator (not shown).

[0050] In the first sequence S1 of a further evasive maneuver 12, the steering angle velocity V increases abruptly. The steering speed V of the first sequence S1 thus corresponds to an abrupt steering input. For example, the previously described steering input is continued with a higher steering angle velocity V. Due to the abrupt increase in the steering speed V, the driver can perceive the continuation of the evasive maneuver 10 haptically, e.g., as a jerk in the steering wheel.

[0051] The first sequence S1 is followed by a further sequence S2 of the subsequent evasive maneuver 12, in which the steering angular velocity V abruptly becomes negative. In the further sequence S2, the steering velocity V is thus associated with a clockwise rotation of the steering wheel (not shown). The steering velocity V in sequence S2 therefore corresponds to an abrupt counter-steering maneuver before passing through the neutral position. For example, in the further sequence S2, the steering wheel is quickly turned back to a neutral position.

[0052] The sequence S2 is followed by a sequence S3 in which the steering speed V is slightly reduced compared to the steering angular velocity V in sequence S2. The steering speed V in sequence S3 thus corresponds to a gentle counter-steering action after passing through the neutral position. For example, the steering wheel (not shown) is turned further clockwise by means of an actuator.

[0053] Sequence S2 is significantly shorter than the subsequent sequence S3. This is because reducing the steering angle L towards a neutral position is less dangerous from a driving dynamics perspective than increasing the steering angle L towards maximum steering lock. This allows the time available for the evasive maneuver to be used effectively for collision avoidance.

[0054] Sequence S3 is followed by a final sequence S4, in which the steering speed V is again positive. The steering angle L is thus returned from a value L22max, for example, to the zero position (see...). Fig. 3) In this way, the motor vehicle can travel at 200 km / h in the direction of travel X (see below). Fig. 1) orient themselves and complete the evasive maneuver 10. At the end of sequence S4, the steering speed V drops to zero, so that the vehicle 200 can continue its journey straight ahead in lane 52.

[0055] Of course, the steering wheel of vehicle 200 does not need to turn to execute evasive maneuver 10. The explanations are merely for better understanding.

[0056] Finally, it should be mentioned that the steering angular velocity V decreases slightly over time during the first compensating movement 11 - and also during the sequences S1, ..., S4 of the further evasive movement 12 - because the motor vehicle 200 is decelerated as part of the evasive maneuver 10 and this affects the steering angular velocity V. Reference symbol list 10 evasive maneuvers 11. First evasive maneuver 12 further evasive maneuvers 50 lane 51 Lane with obstacle 52 lanes without obstacles 100 assistance systems 200 motor vehicles 300 obstacle K1, ..., K4 Clothoid segments of the further evasive movement L steering angle L1 first steering angle profile L1max maximum first steering angle L2 further steering angle profile L21max maximum additional steering angle L22max maximum additional steering angle S1, ..., S4 sequences of further evasive movement T0 Start of the time window T1 End of time window X Lane direction Y transverse direction Z Time window

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