Vehicle driving assistance method and driving assistance device

Abstract

To prevent a series of movements of a vehicle from just before the end of deviation prevention control until immediately after the start of risk avoidance control from giving a feeling of distrust to a driver of the vehicle in a vehicle having a function that performs the deviation prevention control and a function that performs the risk avoidance control.SOLUTION: A method of supporting drive of a vehicle includes the steps of: executing deviation prevention control including steering control to prevent the vehicle from deviating from a travel lane of the vehicle; and starting risk avoidance control from an end timing of the deviation prevention control when operating conditions of risk avoidance control including steering control for avoiding a risk factor in front of the vehicle is met during the execution of the deviation prevention control. The operating conditions of the risk avoidance control include that a longitudinal distance from the vehicle to the risk factor is less than or equal to a reference distance. The method further includes s step of increasing the reference distance during the execution of the deviation prevention control.SELECTED DRAWING: Figure 10

Description

Technical Field

[0001] The present disclosure relates to a method and apparatus for assisting vehicle driving.

Background Art

[0002] Japanese Unexamined Patent Publication No. 2011-73530 discloses a method for assisting vehicle driving. In this conventional method, departure prevention control for preventing a vehicle from departing from a road is performed. In this departure prevention control, a target yaw moment for returning the vehicle to the virtual lane is calculated based on a departure amount from the virtual lane set on the road. The target yaw moment is distributed to a brake control device and a steering control device. The brake control device controls a brake to generate a yaw moment according to the distributed target yaw moment. On the other hand, the steering control device converts the distributed target yaw moment into an assist steering torque, and controls a steering to generate a torque based on the assist steering torque.

Prior Art Literature

Patent Literature

[0003]

Patent Literature 1

Summary of Invention

Problem to be Solved by the Invention

[0004] Methods for assisting vehicle driving include control executed in situations where the vehicle is likely to collide with an obstacle. In the present application, consideration is given to driving assistance control executed in a situation that is one stage earlier than such driving assistance control, that is, in a situation where the vehicle is not highly likely to collide with an obstacle. This driving assistance control is performed to avoid risk factors by regarding pedestrians and the like in front of the vehicle as risk factors. Such driving assistance control is referred to as risk avoidance control in the present application.

[0005] In vehicles equipped with both lane departure prevention control and risk avoidance control functions, the operating conditions for these driver assistance controls are determined independently. The problem arises when the operating conditions for these driver assistance controls are met simultaneously. However, this problem is expected to be resolved by starting the other driver assistance control as soon as the first driver assistance control that was initiated has finished.

[0006] It is conceivable that the above problem would not occur if the activation conditions for the lane departure prevention control and the activation conditions for the risk avoidance control were met with a time gap between them. However, if the time between the end of lane departure prevention control and the start of risk avoidance control is only a few seconds, the series of vehicle behaviors from just before the end of lane departure prevention control to just after the start of risk avoidance control will be awkward and lack a sense of unity. In that case, the series of behaviors is likely to cause distrust in the vehicle's driver.

[0007] One objective of this disclosure is to provide a technology that suppresses the unnatural feeling caused to the driver of a vehicle by a series of vehicle behaviors from just before the end of the lane departure prevention control to just after the start of the risk avoidance control, in a vehicle equipped with a function for lane departure prevention control and a function for risk avoidance control. [Means for solving the problem]

[0008] The first aspect of this disclosure is a method for assisting the driving of a vehicle, which has the following characteristics: The method includes the steps of: performing departure prevention control, which includes steering control to prevent the vehicle from deviating from its driving lane; and, if the conditions for operating risk avoidance control, which includes steering control to avoid risk factors in front of the vehicle, are met while the departure prevention control is being performed, starting the risk avoidance control from the end timing of the departure prevention control. The operating conditions for the risk avoidance control include the longitudinal distance from the vehicle to the risk factor being less than or equal to a reference distance. The method further includes the step of increasing the reference distance while the deviation prevention control is being performed.

[0009] The second aspect of this disclosure is a device that assists in the operation of a vehicle, and has the following features: The device comprises a processor configured to perform various processes. The processor is configured to perform the following: a process to perform departure prevention control, including steering control to prevent the vehicle from deviating from its lane; and a process to start risk avoidance control, including steering control to avoid risk factors in front of the vehicle, from the end of the departure prevention control, if the conditions for operating risk avoidance control are met while the departure prevention control is being performed. The operating conditions for the risk avoidance control include the longitudinal distance from the vehicle to the risk factor being less than or equal to a reference distance. The processor is further configured to perform a process to expand the reference distance while the deviation prevention control is being executed. [Effects of the Invention]

[0010] From the perspective of this disclosure, during the execution of lane departure prevention control, the reference distance included in the operating conditions for risk avoidance control is expanded. The operating conditions for risk avoidance control include the longitudinal distance from the vehicle to the risk factor being less than or equal to the reference distance. Therefore, if the reference distance is expanded, the operating conditions for risk avoidance control become easier to satisfy. Consequently, in situations where a waiting time would occur between the end of lane departure prevention control and the start of risk avoidance control without this expansion, it becomes possible to start risk avoidance control from the moment lane departure prevention control ends. Thus, it becomes possible to reduce the likelihood of the vehicle's behavior from just before the end of lane departure prevention control to just after the start of risk avoidance control causing discomfort to the vehicle's driver. [Brief explanation of the drawing]

[0011] [Figure 1] This is a diagram illustrating risk avoidance control. [Figure 2] This is a diagram illustrating risk avoidance control. [Figure 3] This is a diagram illustrating the lane departure prevention control. [Figure 4]It is a diagram explaining departure prevention control. [Figure 5] It is a diagram explaining features of the embodiment. [Figure 6] It is a diagram explaining features of the embodiment. [Figure 7] It is a diagram explaining features of the embodiment. [Figure 8] It is a diagram explaining features of the embodiment. [Figure 9] It is a block diagram showing a configuration example of a driving support apparatus according to an embodiment. [Figure 10] It is a flowchart showing processing particularly related to the embodiment performed by a control device. Mode for Carrying Out the Invention

[0012] Hereinafter, a vehicle driving support method, a driving support apparatus, and a driving support program according to an embodiment of the present disclosure will be described with reference to the drawings.

[0013] 1. Driving Support Control FIGS. 1 to 4 are diagrams explaining driving support control performed in the embodiment. The driving support apparatus 10 according to the embodiment executes "driving support control" that supports driving of a vehicle VH. This driving support control may be included in automatic driving control. Typically, the driving support apparatus 10 is mounted on the vehicle VH. At least a part of the driving support apparatus 10 may be disposed in a device external to the vehicle VH (e.g., an external server) and perform driving support control remotely. That is, the driving support apparatus 10 may be distributively disposed in the vehicle VH and the external device.

[0014] The driving assistance control includes "risk avoidance control" for avoiding the risk factor 3 in front of the vehicle VH. Risk avoidance control is also referred to as PDA (Proactive Driving Assist) control. In risk avoidance control, the driving assistance device 10 automatically performs at least one of steering and deceleration of the vehicle VH to avoid the risk factor 3 in front of the vehicle VH. For example, in FIG. 1, the vehicle VH is traveling on the lane TL within the roadway RW. The lane TL is demarcated by a left white line LW and a right white line RW provided on the roadway RW. The lane TL corresponds to the "vehicle traveling lane" in the present disclosure. The shoulder RS is adjacent to the lane TL. There is a possibility that the pedestrian 3A present on the shoulder RS in front of the vehicle VH may enter the roadway RW. Therefore, it can be said that the pedestrian 3A is the risk factor 3.

[0015] In the example shown in FIG. 1, the risk avoidance control includes "steering assistance control" that automatically performs steering of the vehicle VH so as to avoid the pedestrian 3A in advance. The risk avoidance control may include "deceleration assistance control" that automatically performs deceleration of the vehicle VH so as to avoid the pedestrian 3A in advance. In the steering assistance control, the driving assistance device 10 steers the vehicle VH in a direction away from the pedestrian 3A. The pedestrian 3A may be replaced with a bicycle or a two-wheeled vehicle. In addition, not only the shoulder RS but also pedestrians, bicycles, two-wheeled vehicles and the like existing on the roadway RW are included in the risk factor 3.

[0016] FIG. 2 is a diagram for explaining another example of risk avoidance control. The risk factor 3 is not limited to "apparent risk" such as the pedestrian 3A shown in FIG. 1. The risk factor 3 can also include "latent risk". For example, in FIG. 2, a parked vehicle 3B exists on the shoulder RS in front of the vehicle VH. The area ahead of the parked vehicle 3B is a blind spot of the vehicle VH, and there is a possibility that a pedestrian 3C may jump out from the blind spot. Therefore, it can be said that the parked vehicle 3B and the pedestrian 3C are the risk factor 3 (latent risk).

[0017] In the example shown in Figure 2, the risk avoidance control includes steering assistance control, which automatically steers the vehicle VH to avoid the parked vehicle 3B in advance. In this steering assistance control, the driver assistance device 10 steers the vehicle VH away from the parked vehicle 3B. As with the example shown in Figure 1, the risk avoidance control may also include deceleration assistance control.

[0018] Here, we define the vehicle coordinate system (X,Y). The vehicle coordinate system (X,Y) is a relative coordinate system fixed to the vehicle VH, and changes as the vehicle VH moves. The X direction is the forward direction (direction of travel) of the vehicle VH. The Y direction is the lateral direction of the vehicle VH. The X and Y directions are orthogonal to each other.

[0019] In Figures 1 and 2, trajectory TR0 represents the trajectory of vehicle VH when steering assist control is not performed. When steering assist control is not performed, it is assumed that vehicle VH travels parallel to lane TL. Therefore, trajectory TR0 extends parallel to lane TL from the current position of vehicle VH. In the following explanation, lateral distance Dy is the shortest distance between trajectory TR0 and risk factor 3. In other words, lateral distance Dy is the distance in the Y direction between vehicle VH (trajectory TR0) and risk factor 3 as vehicle VH passes to the side of risk factor 3.

[0020] In Figures 1 and 2, trajectory TR1 represents the trajectory of vehicle VH when steering assist control is performed. When steering assist control is performed, vehicle VH moves away from risk factor 3. Lateral displacement δDy is the amount of vehicle VH moved away from risk factor 3 due to steering assist control. In other words, lateral displacement δDy is the amount of vehicle VH moved away from risk factor 3 as seen from trajectory TR0.

[0021] The driver assistance control also includes "departure prevention control" to prevent the vehicle VH from deviating from the lane TL. Departure prevention control is also called LDA (Lane Departure Alert) control. In departure prevention control, the driver assistance device 10 automatically steers and decelerates the vehicle VH to prevent the vehicle VH from deviating from the lane TL. For example, in Figure 3, the longitudinal axis of the vehicle VH is offset by an angle θy with respect to the reference line RL on the lane TL. The offset angle θy is the angle between the longitudinal axis of the vehicle VH passing through the reference point RP and the reference line RL, and is sometimes called the yaw angle. The reference line RL is set along the lane TL passing through the reference point RP. Therefore, the reference line RL may coincide with the center line CL of the lane TL, or it may not coincide with the center line CL.

[0022] Figure 3 shows the lateral distance Ds from the reference point RP to the left white line LW. The lateral distance Ds is also the distance from the reference point RP to the right white line RW. Lane departure prevention control is performed when the vehicle VH is about to deviate outside the lane TL. Figure 4 is a diagram illustrating the lane departure prevention control. In the example shown in Figure 4, the lane departure prevention control includes "steering assistance control," which automatically steers the vehicle VH to prevent it from deviating outside the left white line LW. The lane departure prevention control may also include "deceleration assistance control," which automatically decelerates the vehicle VH to prevent it from crossing the left white line LW.

[0023] In steering assistance control, the driver assistance device 10 steers the vehicle VH away from the left white line LW. The driver assistance device 10 also steers the vehicle VH towards the center line CL. When the vehicle VH is steered away from the left white line LW, the deviation angle θy, as explained in Figure 3, decreases. The steering assistance control includes a first control (hereinafter also referred to as "first LDA control") until the deviation angle θy coincides with a specified angle θy0 in which the longitudinal axis of the vehicle VH is considered to be parallel to the reference line RL. The steering assistance control also includes a second control (hereinafter also referred to as "second LDA control") that follows this first control. In the second control, the vehicle VH is steered towards the center line CL until the lateral distance Ds in the left and right directions both fall within a predetermined range. The predetermined range is set according to the width of the lane TL.

[0024] 2. Characteristics of the Embodiment As previously mentioned, if the time between the end of lane departure prevention control and the start of risk avoidance control is only a few seconds (for example, 1 to 3 seconds), the series of vehicle behaviors from just before the end of lane departure prevention control to just after the start of risk avoidance control will be awkward and lack a sense of unity. Figures 5 and 6 illustrate this problem. In the examples shown in Figures 5 and 6, lane departure prevention control has already started.

[0025] In the example shown in Figure 5, pedestrian 3D is located on the shoulder RS ​​to the left front of vehicle VH. In the example shown in Figure 6, pedestrian 3E is located on the shoulder RS ​​to the right front of vehicle VH. Pedestrians 3D and 3E correspond to risk factor 3. However, the activation conditions for risk avoidance control include the longitudinal distance DX from vehicle VH to risk factor 3 being less than or equal to the reference distance RD. Therefore, the system will wait to start risk avoidance control until the longitudinal distance condition is met. During this waiting time, vehicle VH will continue to travel as is. However, if the non-operational section in which neither lane departure prevention control nor risk avoidance control operates is short, it will lead to the series of vehicle behaviors described above.

[0026] Therefore, in this embodiment, a process is performed to expand the reference distance RD while the deviation prevention control is being executed. The expanded reference distance RD is referred to as "reference distance RD*". When the reference distance RD is changed to reference distance RD*, the conditions for operating risk avoidance control are more likely to be met while the deviation prevention control is being executed. As a result, it becomes possible to suppress a situation where the system has to wait for the start of risk avoidance control after the completion of deviation prevention control.

[0027] If the activation conditions for risk avoidance control are met while lane departure prevention control is being executed, risk avoidance control is initiated from the point when lane departure prevention control ends. By initiating risk avoidance control from the point when lane departure prevention control ends, lane departure prevention control and risk avoidance control can be performed continuously. Therefore, it is possible to minimize the sense of unease the driver of the vehicle (VH) during the series of vehicle behaviors from just before the end of lane departure prevention control to just after the start of risk avoidance control.

[0028] Risk avoidance control may be initiated from the end timing of the first LDA control, as explained in Figure 4. Figures 7 and 8 illustrate the vehicle behavior when risk avoidance control is initiated from the end timing of the first LDA control. The external environment of vehicle VH shown in Figure 7 is the same as that explained in Figure 5. Similarly, the external environment of vehicle VH shown in Figure 8 is the same as that explained in Figure 6.

[0029] The termination timing of the lane departure prevention control includes the termination timing of the second LDA control and the termination timing of the first LDA control. If risk avoidance control is started from the termination timing of the second LDA control, the effects described above can be expected. However, the objective of the lane departure prevention control (departure prevention) is achieved at the termination timing of the first LDA control, which is before the termination timing of the second LDA control. Therefore, there is no problem in starting risk avoidance control from the termination timing of the first LDA control. Rather, in the situation shown in Figure 8, starting risk avoidance control from the termination timing of the first LDA control contributes to stabilizing the steering behavior of the vehicle VH.

[0030] 3. Driving assistance systems 3-1. Example Configuration Figure 9 is a block diagram showing an example configuration of the driver assistance device 10 according to the embodiment. In the example shown in Figure 9, the driver assistance device 10 includes a sensor group 20, a driving device 30, and a control device 40.

[0031] The sensor group 20 includes, for example, a position sensor, a state sensor, and a recognition sensor. The position sensor detects the position and orientation of the vehicle VH. An example of a position sensor is a GPS (Global Positioning System) sensor. The state sensor detects the internal state of the vehicle VH. An example of a state sensor is a vehicle speed sensor, a yaw rate sensor, a lateral acceleration sensor, a steering angle sensor, etc. The recognition sensor recognizes (detects) the surrounding conditions of the vehicle VH. An example of a recognition sensor is a camera, radar, lidar (Laser Imaging Detection and Ranging), etc.

[0032] Each sensor included in the sensor group 20 transmits detected or recognized information to the control device 40. The information transmitted from each sensor to the control device 40 constitutes driving environment information ENV. Driving environment information ENV also includes map information. Map information includes information such as lane layout and road shape. Map information is stored, for example, in a predetermined storage device of the vehicle VH. Map information may also be stored in an external device (for example, an external server) of the vehicle VH.

[0033] The running gear 30 includes a steering gear, a drive gear, and a braking gear. The steering gear steers the wheels of the vehicle VH. For example, the steering gear includes an electric power steering (EPS) system. The drive gear is a power source that generates driving force. Examples of drive gears include an engine, an electric motor, and an in-wheel motor. The braking gear generates braking force.

[0034] The control device 40 controls the vehicle VH. Typically, the control device 40 is a microcomputer mounted on the vehicle VH. The control device 40 is also called an ECU (Electronic Control Unit). The control device 40 may also be an external information processing device to the vehicle VH. In this case, the control device 40 communicates with the vehicle VH and controls the vehicle VH remotely.

[0035] The control device 40 includes a processor 41 and a storage device 42. The processor 41 performs various processes. The storage device 42 is a volatile memory, non-volatile memory, etc., and various information is stored therein. Examples of various information include operating environment information ENV. Various information also includes control information CON that is transmitted to the traveling device 30. The processor 41 performs various processes by executing a control program, which is a computer program. The control program is stored in the storage device 42 or recorded on a computer-readable recording medium.

[0036] 3-2. Example of processing by a control device Figure 10 is a flowchart showing the processing particularly related to driver assistance control performed by the processor 41. The processing flow shown in Figure 10 is executed repeatedly at a predetermined calculation cycle.

[0037] In the processing flow shown in Figure 10, it is first determined whether or not the LDA activation conditions are met (step S11). The LDA activation conditions include various conditions for determining whether or not the vehicle VH deviates outside the lane TL. These conditions include, for example, the deviation angle θy and the lateral distance Ds as determination parameters. The condition that the vehicle VH is approaching a curve may also be included in the various conditions.

[0038] If the result of step S11 is positive, LDA control (i.e., lane departure prevention control) is started (step S12). In lane departure prevention control, a target torque is calculated to prevent the vehicle VH from deviating from lane TL, based on, for example, the deviation angle θy, the lateral distance Ds, the speed of the vehicle VH, the curve radius of the lane TL, the yaw rate of the vehicle VH, etc. Alternatively, a target steering angle may be calculated to prevent the vehicle VH from deviating from lane TL. Then, control information CON indicating the target torque (or target steering angle) is transmitted to the running gear 30 (steering gear).

[0039] Following the processing in step S12, the reference distance RD is changed to the reference distance RD* (>RD) (step S13). The processing in step S13 may be performed in parallel with the processing in step S12. Note that the reference distance RD and reference distance RD* are set variably according to the speed of the vehicle VH.

[0040] Following the processing in step S13, it is determined whether the first LDA control has finished (step S14). The processing in step S14 is performed, for example, by determining whether the displacement angle θy has decreased to a specified angle θy0 or less. If the determination result in step S14 is positive, the reference distance RD* is changed to the reference distance RD (step S15). In other words, the reference distance RD is set to the default value. Note that in the processing of step S14, instead of determining whether the first LDA control has finished, it may be determined whether the second LDA control has finished. In this case, the processing in step S14 determines whether the lateral distance Ds in the left and right directions are both within a predetermined range.

[0041] If the result of step S14 is negative, it is determined whether the PDA activation conditions are met (step S16). The PDA activation conditions include various conditions for determining whether there is a risk of vehicle VH colliding with an obstacle ahead. These conditions include the recognition of risk factor 3 in front of vehicle VH. The conditions also include the fact that the longitudinal distance DX from vehicle VH to this risk factor 3 is less than or equal to the reference distance RD (or reference distance RD* if a reference distance RD* is set).

[0042] If the result of step S16 is negative, the process in step S14 is performed. In other words, the processes in steps S14 and S16 are repeated until the first LDA control is completed. If the result of step S16 is positive, PDA control (i.e., risk avoidance control) is started. In risk avoidance control, a trajectory is generated to move the vehicle VH away from risk factor 3. Then, the target torque, target acceleration, etc., of the vehicle VH are calculated so that the vehicle VH follows this trajectory. Instead of the target torque, a target steering angle for the vehicle VH to follow the trajectory may be calculated. Then, control information CON indicating the target torque (or target steering angle) is transmitted to the running gear 30 (steering gear).

[0043] 3A, 3C, 3D, 3E Pedestrians, 3B Parked Vehicles, 10 Driving Assistance Systems, 41 Processor, 42 Memory, CL Center Line, TL Lane, RL Reference Line, RP Reference Point, VH Vehicle, CON Control Information, ENV Driving Environment Information

Claims

1. A method for assisting the driving of a vehicle, The steps include performing a departure prevention control, which includes steering control to prevent the vehicle from deviating from its lane, If, during the execution of the departure prevention control, the conditions for operating risk avoidance control, including steering control to avoid risk factors in front of the vehicle, are met, the step of starting the risk avoidance control from the timing of the termination of the departure prevention control, Includes, The operating conditions for the risk avoidance control include the longitudinal distance from the vehicle to the risk factor being less than or equal to a reference distance, The execution of the deviation prevention control further includes the step of increasing the reference distance. A method for assisting the driving of a vehicle, characterized by the features described above.

2. The method according to claim 1, The steering control included in the lane departure prevention control includes: a first steering control that steers the vehicle so that the longitudinal axis of the vehicle is parallel to a reference line set along the driving lane passing through the vehicle's reference point; and a second steering control that follows the first steering control and steers the vehicle so that the lateral position of the vehicle in the driving lane is toward the center of the driving lane. The termination timing of the deviation prevention control includes the termination timing of the first steering control. A method for assisting the driving of a vehicle, characterized by the features described above.

3. A method according to claim 1 or 2, The steering control included in the lane departure prevention control includes: a first steering control that steers the vehicle so that the longitudinal axis of the vehicle is parallel to a reference line set along the driving lane passing through the vehicle's reference point; and a second steering control that follows the first steering control and steers the vehicle so that the lateral position of the vehicle in the driving lane is toward the center of the driving lane. The expansion of the reference distance is performed during the execution of the first steering control. A method for assisting the driving of a vehicle, characterized by the features described above.

4. A device that assists in the operation of a vehicle, It has a processor configured to perform various processes, The aforementioned processor, A process for performing departure prevention control, including steering control to prevent the vehicle from deviating from its lane, If, during the execution of the aforementioned departure prevention control, the conditions for operating risk avoidance control, including steering control to avoid risk factors in front of the vehicle, are met, the process of starting the risk avoidance control from the timing of the termination of the aforementioned departure prevention control, It is configured to do the following: The operating conditions for the risk avoidance control include the longitudinal distance from the vehicle to the risk factor being less than or equal to a reference distance, The aforementioned processor further, During the execution of the deviation prevention control, the process of expanding the reference distance is performed. A vehicle driving assistance device characterized by being configured in such a way.

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