Method for longitudinal control of a motor vehicle and driver assistance system

Abstract

The invention relates to a method for longitudinal control of a motor vehicle (1), wherein the motor vehicle (1) has a driver assistance system (10) for automatic longitudinal control, by means of which at least a desired distance to a preceding motor vehicle (2) is automatically maintained, wherein the driver assistance system (10) accesses data from a road map, wherein the driver assistance system (10) determines intersecting roads based on the road map, wherein the driver assistance system (10) determines at least one conflict area (CA), wherein the conflict area (CA) is an area that other vehicles cross in order to enter or exit the intersecting road, wherein, upon detection of a necessary stop behind the preceding motor vehicle (2), it is determined whether the motor vehicle (1) would come to a stop in the conflict area (CA), wherein at least one parameter of the longitudinal control is then adjusted accordingly.that the motor vehicle (1) does not come to a stop in the conflict area (KF), as well as a driver assistance system (10).

Description

[0001] The invention relates to a method for longitudinal control of a motor vehicle and a driver assistance system.

[0002] Today's longitudinal control systems maintain a desired speed and a desired distance from the vehicle in front. Such driver assistance systems are also known as ACC (Adaptive Cruise Control) systems. If the vehicle in front stops, the longitudinally controlled vehicle also stops at a defined distance of one or a few meters behind the vehicle in front.

[0003] Such a system is known, for example, from US 11 136 026 B2. It also discloses that an environmental sensor system detects obstacles in an oncoming lane. If the vehicle then has to stop, for example, because a vehicle ahead has to stop at a traffic light, the vehicle is brought to a stop in front of the obstacle so that vehicles in the oncoming lane can still avoid the obstacle. In other words, the stopping point is adjusted to avoid a traffic jam at the obstacle for oncoming traffic.

[0004] From DE 10 2018 220 844 A1 and DE 10 2014 220 685 A1, generic methods for the longitudinal control of a motor vehicle are known.

[0005] From DE 10 2018 205 199 A1 a method for determining a swarm-based stopping point for a motor vehicle for a given stopping reason on a lane of a roadway is known, comprising the steps: - Determining individual stopping points of a plurality of vehicles for the stopping reason in the lane, whereby the vehicles are controlled by individual drivers, - Determining a distribution of the individual stopping points on the lane at least in the direction of travel of the vehicles, and - Determine the maximum of the distribution and store the maximum of the distribution as a swarm-based breakpoint.

[0006] The invention is based on the technical problem of providing an improved method for longitudinal control of a motor vehicle which improves traffic flow.

[0007] Another technical problem is the creation of an appropriate driver assistance system.

[0008] The solution to the technical problem results from a method having the features of claim 1 and a driver assistance system having the features of claim 9. Further advantageous embodiments of the invention result from the subclaims.

[0009] The method for longitudinal control of a motor vehicle is carried out by means of a driver assistance system for automatic longitudinal control, by means of which at least a desired distance from a motor vehicle traveling ahead is automatically maintained. Preferably, a desired speed is also maintained. The desired distance is preferably speed-dependent, with the distance to be maintained being reduced as speed decreases. The driver assistance system accesses data from a road map, wherein the driver assistance system determines intersecting roads based on the road map. Intersecting roads is to be understood generally here and includes streets that merge into one another. The driver assistance system also determines at least one conflict area, wherein the conflict area is an area that other vehicles drive over in order to enter or exit the intersecting road.If a necessary stop is detected behind the vehicle in front, it is determined whether the vehicle would come to a stop in the conflict area. It should be noted that the order of the process steps can also be reversed here, meaning that a conflict area is only calculated if a necessary stop is previously expected. If the vehicle would come to a stop in the conflict area, at least one parameter of the longitudinal control is adjusted so that the vehicle does not come to a stop in the conflict area.

[0010] For example, the distance to the vehicle in front can be reduced when stopping in order to keep the conflict area clear. Another option is to increase the distance when stopping in order to bring the vehicle to a stop before the conflict area. In this case, the following speed is initially reduced when a first probability value for a necessary stop is detected, so that when a second probability value is reached, the vehicle can be brought to a stop specifically before or behind the conflict area. The advantage of adjusting the speed is that it is then generally easier to stop before the conflict area (shorter braking distance).

[0011] The driver is informed of a stop before or after the collision zone. This information can be provided graphically on a display unit and / or acoustically. This prevents the driver from being surprised by the vehicle's behavior and, if necessary, from intervening manually.

[0012] In one embodiment, the road map is a swarm map, where driving paths out of or into the intersecting road are extracted from the road map, and the conflict area is determined based on the driving paths. This significantly simplifies the determination of the conflict area compared to a digital road map. A swarm map is based on swarm data collected by other vehicles. This data is typically generated using cameras. Alternatively or additionally, radar, lidar, and / or ultrasonic sensors, as well as speed data, can also be used. The swarm map then provides lane markings, road edges, and driving paths (“drivable path”). This is the path that most vehicles have traveled.By creating a conflict area around the drivable path with a width at least slightly larger than the average vehicle width, the relevant conflict area can be accurately predicted and thus not set unnecessarily large. The width of the conflict area is preferably between 3 m and 4 m.

[0013] In another embodiment, the dimensions of the conflict area are adjusted depending on a standard deviation or other percentile. This means that with a larger standard deviation, the conflict area becomes correspondingly wider, so that the conflict area better adapts to real-world traffic patterns.

[0014] Preferably, a maximum width of the conflict area is specified, which must not be exceeded. This prevents the distance to the vehicle in front from becoming arbitrarily large. This can lead to traffic situations in which the conflict area is limited to the maximum width or, if necessary, even has to be ignored completely. The maximum value can be changed by an application.

[0015] Furthermore, multiple conflict areas can occur consecutively, resulting from multiple driving paths. In this case, the area between the conflict areas must be evaluated. If the area is wider than one vehicle length, it can be used for stopping. If, however, the width is smaller than one vehicle length, the conflict areas are merged into a single conflict area. However, as previously described, the width can be limited to a maximum value.

[0016] In one embodiment, the detection of a necessary stop is carried out using a distance sensor system, which, for example, comprises radar, lidar, and / or camera sensors. Additionally or alternatively, the detection of a necessary stop can also be carried out using Car2X information and / or the detected colors of a traffic light. For example, the vehicle ahead and / or a traffic light can transmit data from which a necessary stop can be determined. Alternatively or additionally, a red or yellow phase can be detected, for example, using a camera.

[0017] In a further embodiment, data from a motor vehicle traveling in front of the preceding motor vehicle are additionally taken into account to determine a necessary stop. This further improves the detection of an impending necessary stop.

[0018] In a further embodiment, the driver can use at least one actuating element to deliberately steer the vehicle into the conflict area, for example, because the driver recognizes that this does not currently impede onward traffic. The actuating element can be, for example, a button and / or the accelerator pedal.

[0019] In a further embodiment, before starting up again, it is checked whether the conflict area can be crossed before the motor vehicle has to be stopped again, whereby starting up again is omitted if there is a risk that the approaching motor vehicle could come to a stop in the conflict area.

[0020] The driver assistance system for automatic longitudinal control is designed to automatically maintain a desired distance from a motor vehicle traveling ahead. The driver assistance system can access data from a road map and determines intersecting roads based on the road map. Furthermore, the driver assistance system is designed to determine at least one conflict area, the conflict area being an area that other vehicles drive over to enter or exit the intersecting road. Upon detection of a necessary stop behind the motor vehicle traveling ahead, it is determined whether the motor vehicle would come to a stop in the conflict area. At least one parameter of the longitudinal control is then adjusted such that the motor vehicle does not come to a stop in the conflict area.

[0021] The driver assistance system is designed in such a way that the following speed is initially reduced when a first probability value for a necessary stop is detected, whereby when a second probability value is reached the motor vehicle can be brought to a stop specifically in front of or behind the conflict area, whereby the motor vehicle driver is informed of a stop in front of or behind the conflict area.

[0022] With regard to the further possible design of the driver assistance system, reference is made in full to the previous explanations of the method.

[0023] The invention is explained in more detail below using a preferred embodiment. The figures show: Fig. 1 a schematic example of a traffic situation, Fig. 2 a block diagram of a driver assistance system and Fig. 3 a flow chart of the procedure.

[0024] In the Fig. 1 shows a highly schematic illustration of an exemplary traffic situation to explain the method. There is a main road HS with dashed lane markings FB. The motor vehicle 1 with the driver assistance system according to the invention is traveling from right to left, which is symbolized by the arrow. The motor vehicle 1 intends to stay straight ahead on the main road HS. Furthermore, there is a secondary road NS that crosses the main road HS. A traffic island VI is arranged in the secondary road NS. Furthermore, a driving path FV1 of vehicles turning from the opposite direction of the main road HS onto the secondary road NS is shown, and a driving path FV2 of vehicles turning from the secondary road NS into the opposite direction of the main road HS is shown. Therefore, the motor vehicle 1 will intersect the driving paths FV1, FV2. Also shown are a preceding motor vehicle 2 and a motor vehicle 3 traveling in front of the preceding motor vehicle 2.Also shown is a conflict area KF. The conflict area KF is defined in such a way that vehicles following the routes FV1,2 must drive through this conflict area KF. The width B is dimensioned accordingly and takes into account the average width of the vehicles. If motor vehicle 1 were to come to a stop in the conflict area KF, this would prevent the traffic flow of other vehicles. If motor vehicle 1 or its driver assistance system detects a necessary stop (for example because motor vehicles 2, 3 are at a traffic light not shown), a check is carried out to determine whether motor vehicle 1 would come to a stop in the conflict area KF. This would be the case here, so that motor vehicle 1 would come to a stop before the conflict area KF. This would be the case here, so that motor vehicle 1 is brought to a stop before the conflict area KF.This stopping area HF in front of the conflict area KF is selected in such a way that it hinders other road users as little as possible.

[0025] In the Fig. Figure 2 shows a highly schematic illustration of a driver assistance system 10 for automatic longitudinal control. The driver assistance system 10 has an evaluation and control unit 11 and generates signals S for the actuators of the longitudinal dynamics. The driver assistance system 10 receives data from a distance sensor system 12, which is designed, for example, as a radar and / or lidar sensor system. The driver assistance system 10 also receives data from at least one camera 13 and a control unit 14 for receiving CAR2X information. It is further shown that the driver assistance system 10 can access a swarm map SK in a memory 15. The swarm map SK is adapted depending on the position of the motor vehicle 1, for which purpose a control unit 16 retrieves data from a cloud server 17 and stores it in the memory 15.Also shown is a display and control unit 18 on which information is displayed to explain standing on the holding area HF, wherein an actuating element 19 is additionally shown, upon actuation of which the motor vehicle 1 is parked in the conflict area KF.

[0026] Finally, in Fig.3 shows a flow diagram of the method, wherein the method is started in a first step S1. In a second step S2, a check is made to determine whether a stop is necessary. If this is not the case, the method returns to the first step S1. If, however, this is determined, in a third step S3, the swarm map SK is used to determine whether an merging or crossing road exists in the stopping path. If no road is found, the motor vehicle 1 is brought to a stop at a defined target distance behind the preceding motor vehicle 2 (fourth step S4). Otherwise, a conflict area KF is identified or determined in a fifth step S5. In a sixth step S6, it is then determined whether the motor vehicle 1 would come to a stop in the conflict area KF.If this is denied, in a seventh step S7, as in step S4, the motor vehicle 1 is brought to a stop at a defined target distance behind the preceding motor vehicle 2. Otherwise, in an eighth step S8, at least one parameter of the longitudinal control is adjusted so that the motor vehicle 1 can come to a stop in front of or behind the conflict area KF. For example, the target distance is reduced or the speed is reduced and the motor vehicle 1 is parked at a greater target distance from the preceding motor vehicle 2. In a ninth step S9, the motor vehicle 1 is then parked on the calculated stopping area HF in front of or behind the conflict area KF. In a tenth step S10, it is checked whether an actuating element 19 has been actuated. If this is the case, in an eleventh step S11 the motor vehicle 1 is moved into the conflict area KF and parked there. In a twelfth step S12, it is checked whether a restart (e.g.the preceding motor vehicle 2 has moved) is possible without possibly being forced to stop again in the conflict area KF. If this is not guaranteed, motor vehicle 1 stops (step S13) and step S12 is repeated. If further travel is possible, motor vehicle 1 starts moving (step S14) and the process returns to the first step S1. List of reference symbols 1 motor vehicle 2 motor vehicles 3 Motor vehicle 10 Driver assistance system 11 Evaluation and control unit 12 Distance sensors 13 Camera 14 Control unit 15 storage 16 Control unit 17 cloud servers 18 Display and control unit 19 Actuating element HS Main Street FB Road Marking NS side street VI Traffic island FV1 driving route FV2 driving route KF conflict area B Width S Signal SK swarm map S1 - S14 Process steps

Claims

[1] A method for longitudinal control of a motor vehicle (1), wherein the motor vehicle (1) has a driver assistance system (10) for automatic longitudinal control, by means of which at least a desired distance to a preceding motor vehicle (2) is automatically maintained, wherein the driver assistance system (10) accesses data from a road map, wherein the driver assistance system (10) determines intersecting roads based on the road map, wherein the driver assistance system (10) determines at least one conflict area (KF), wherein the conflict area (KF) is an area that other vehicles drive over in order to enter or exit the intersecting road, wherein upon detection of a necessary stop behind the preceding motor vehicle (2), it is determined whether the motor vehicle (1) would come to a stop in the conflict area (KF), wherein at least one parameter of the longitudinal control is then adjusted such that the motor vehicle (1) does not come to a stop in the conflict area (KF),characterized by that the following speed is initially reduced when a first probability value for a necessary stop is detected, whereby when a second probability value is reached the motor vehicle can be brought to a stop specifically in front of or behind the conflict area, whereby the motor vehicle driver is informed of a stop in front of or behind the conflict area (KF). [2] Method according to claim 1, characterized by that the road map is a swarm map (SK), whereby driving paths (FV1, FV2) from or into the intersecting road are read out of the road map, whereby the conflict area (KF) is determined depending on the driving paths (FV1, FV2). [3] Method according to one of the preceding claims, characterized by that the dimensions of the conflict area (KF) are adjusted depending on a standard deviation of the driving paths (FV1, FV2). [4] Method according to one of the preceding claims, characterized by that the detection of a necessary stop is carried out by means of a distance sensor (12). [5] Method according to one of the preceding claims, characterized by that the detection of a necessary stop is carried out based on CAR2X information and / or detected colours of a traffic light system. [6] Method according to one of the preceding claims, characterized by that the data of a motor vehicle (3) traveling in front of the preceding motor vehicle (2) are additionally taken into account in order to determine whether a stop is necessary. [7] Method according to one of the preceding claims, characterized by that the motor vehicle driver can steer the motor vehicle (1) into the conflict area (KF) by means of at least one actuating element (19) and can thus override the driver assistance system (10). [8] Method according to one of the preceding claims, characterized bythat before starting up again, it is checked whether the conflict area (KF) can be crossed before the motor vehicle (1) has to be stopped again, whereby starting up again is omitted if there is a risk that the starting motor vehicle (1) could come to a stop in the conflict area (KF). [9] Driver assistance system (10) for automatic longitudinal control, wherein the driver assistance system (10) is designed to automatically maintain a desired distance from a motor vehicle (2) traveling ahead, wherein the driver assistance system (10) is further designed to access data from a road map and to determine intersecting roads based on the road map, wherein the driver assistance system (10) determines at least one conflict area (KF), wherein the conflict area (KF) is an area that other vehicles drive over in order to enter or exit the intersecting road, wherein upon detection of a necessary stop behind the motor vehicle (2) traveling ahead, it is determined whether the motor vehicle (1) would come to a stop in the conflict area (KF), wherein at least one parameter of the longitudinal control is then adjusted such that the motor vehicle (1) does not come to a stop in the conflict area (KF), characterized byin that the driver assistance system (10) is designed such that the following speed is initially reduced when a first probability value for a necessary stop is detected, wherein when a second probability value is reached the motor vehicle can then be brought to a stop in a targeted manner in front of or behind the conflict area, wherein the motor vehicle driver is informed of a stop in front of or behind the conflict area (KF).

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