Driver assistance device, driver assistance method, and non-transitory computer-readable storage medium storing program

Abstract

A driver assistance device includes a processor configured to: automatically decelerate the own vehicle based on a relative relationship between the own vehicle and a preceding vehicle traveling ahead of the own vehicle; change the deceleration of the own vehicle by a first change amount or a second change amount greater than the first change amount when automatically decelerating the own vehicle; perform a behavior determination to estimate whether the behavior of the own vehicle will become unstable when the own vehicle is automatically decelerated; and, when the behavior of the own vehicle is estimated to become unstable, change the deceleration by the first change amount when automatically decelerating the own vehicle.

Description

Technical Field

[0001] The present invention relates to a driver assistance device, a driver assistance method, and a non-transitory computer-readable storage medium storing a program. Background Art

[0002] As an apparatus of this type, for example, a device has been proposed that controls the inter-vehicle distance between the own vehicle and a vehicle traveling ahead, and calculates the degree of collision risk felt by the driver when another vehicle cuts in front or switches to a target inter-vehicle distance from the vehicle traveling ahead, such that the higher the calculated degree of collision risk, the greater the jerk that is generated to decelerate the own vehicle (see Japanese Unexamined Patent Application Publication No. 2015-120363 (JP 2015-120363A)). Summary of the Invention

[0003] However, for example, if a relatively large jump is set simply because the collision risk is relatively high, thereby causing the vehicle to decelerate suddenly, there is a possibility that the behavior of the vehicle will become unstable. That is, there is room for improvement in the technology described in JP 2015-120363A.

[0004] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a driver assistance device and method, and a computer program capable of appropriately decelerating a vehicle while suppressing the behavior of the vehicle from becoming unstable.

[0005] One aspect of the present invention relates to a driver assistance device including a processor configured to: automatically decelerate a vehicle based on a relative relationship between the vehicle and a preceding vehicle traveling ahead of the vehicle; change the deceleration of the vehicle by a first change amount or a second change amount greater than the first change amount when automatically decelerating the vehicle; perform a behavior determination to estimate whether the behavior of the vehicle will become unstable when the vehicle is automatically decelerated; and, when the behavior of the vehicle is estimated to become unstable, change the deceleration by the first change amount when automatically decelerating the vehicle.

[0006] One aspect of the present invention relates to a driver assistance method for a vehicle. The vehicle is configured to automatically decelerate the vehicle based on a relative relationship between the vehicle and a preceding vehicle currently traveling ahead of the vehicle; and to change the vehicle's deceleration by a first change amount or a second change amount greater than the first change amount when automatically decelerating the vehicle. The driver assistance method includes estimating whether the vehicle's behavior will become unstable when the vehicle automatically decelerates; and, if the vehicle's behavior is estimated to become unstable, changing the deceleration by the first change amount when automatically decelerating the vehicle.

[0007] One aspect of the present invention relates to a non-transitory computer-readable storage medium having a program stored thereon. When executed by a processor of a driver assistance device configured to automatically decelerate a vehicle based on a relative relationship between the vehicle and a preceding vehicle currently traveling ahead of the vehicle, the program causes the driver assistance device to: change the vehicle's deceleration by a first change amount or a second change amount greater than the first change amount when automatically decelerating the vehicle; estimate whether the vehicle's behavior will become unstable when the vehicle automatically decelerates; and, if the vehicle's behavior is estimated to become unstable, change the deceleration by the first change amount when automatically decelerating the vehicle.

[0008] In addition to considering the relative relationship between the host vehicle and the vehicle traveling ahead, the present driver assistance device, method, and computer program also consider the stability of the host vehicle's behavior. Therefore, the present driver assistance device, method, and computer program can appropriately decelerate the host vehicle while suppressing instability in the host vehicle's behavior due to deceleration. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Features, advantages, and technical and industrial significance of exemplary embodiments of the present invention will be described below with reference to the accompanying drawings, wherein like numerals represent like elements, and wherein:

[0010] Figure 1 A block diagram illustrating a configuration of a driver assistance device according to one embodiment;

[0011] Figure 2 is a flowchart showing the operation of the driver assistance device according to this embodiment; and

[0012] Figure 3 It is a block diagram illustrating the configuration of a computer according to this embodiment. DETAILED DESCRIPTION

[0013] Will refer to Figure 1 and Figure 2 An embodiment related to a driver assistance device is described. Figure 1 In the embodiment, a driver assistance device 100 is installed in a vehicle 1 (omitted from the illustration). The driver assistance device 100 is capable of causing the vehicle 1 to travel so as to follow a preceding vehicle, which is another vehicle traveling ahead of the vehicle 1. That is, the driver assistance device 100 is configured to be able to perform the following type of Adaptive Cruise Control (ACC). The driver assistance device 100 is configured to be able to implement deceleration assist control, in which the braking device 30 of the vehicle 1 is used, for example, to automatically decelerate the vehicle 1, for example, while performing the following type of ACC, while controlling the inter-vehicle distance between the vehicle 1 and the preceding vehicle according to their relative relationship.

[0014] Note that, in the present embodiment, a form in which the deceleration assist control is implemented during execution of the following type of ACC is given as an example, but it is not limited thereto.

[0015] In order to implement deceleration assist control, the driver assistance device 100 is configured to include, as a processing block logically implemented therein or as a processing circuit physically implemented therein: an external environment recognition unit 11, a preceding vehicle information calculation unit 12, a stable behavior determination unit 13, a necessary deceleration calculation unit 14, an alarm implementation determination unit 15, a jump suppression implementation determination unit 16, an acceleration control unit 17 and an end determination unit 18.

[0016] Here, the sensors 20 provided on the vehicle 1 include sensors for identifying the external environment of the vehicle 1, such as radar, light detection and ranging (LiDAR), and cameras, as well as sensors for detecting the motion state of the vehicle 1, such as speed sensors, acceleration sensors, and yaw rate sensors.

[0017] The external environment recognition unit 11 obtains measurement results from sensors included in the sensor 20 for recognizing the external environment of the vehicle 1. Furthermore, the external environment recognition unit 11 may obtain, for example, Intelligent Transport System (ITS) information. For example, the external environment recognition unit 11 may obtain information from another vehicle traveling near the vehicle 1 via vehicle-to-vehicle communication.

[0018] The external environment recognition unit 11 recognizes the external environment of the vehicle 1 based on the acquired measurement results and ITS information. Examples of the external environment include objects such as other vehicles and obstacles, meteorological conditions such as air temperature and rainfall, and road surface information such as road markings and road surface temperature. Note that various existing methods can be applied as a method for recognizing the external environment, and accordingly, a detailed description thereof will be omitted.

[0019] When a preceding vehicle (ie, another vehicle traveling ahead of the vehicle 1 while the vehicle 1 is traveling) is recognized by the external environment recognition unit 11 , the preceding vehicle information calculation unit 12 calculates preceding vehicle information related to the preceding vehicle.

[0020] Specifically, the preceding vehicle information calculation unit 12 may calculate reliability as the preceding vehicle information. Here, "reliability" may be an indicator of the certainty of the presence of the preceding vehicle. Such reliability may be calculated based on determinations such as (i) whether the preceding vehicle is detected by multiple types of sensors included in the sensor 20, (ii) whether the preceding vehicle is continuously detected by at least one sensor included in the sensor 20, and (iii) whether the preceding vehicle is continuously controlled by the aforementioned deceleration assist control.

[0021] Alternatively, the “reliability” may be an indicator indicating the certainty that the preceding vehicle exists in the same lane as the lane in which the vehicle 1 is currently traveling. Such reliability may be calculated based on, for example, (i) a comparison result between the position of the preceding vehicle predicted based on the recognition result of the external environment recognition unit 11 or the like and the predicted route of the vehicle 1, (ii) a determination result as to whether the preceding vehicle exists between road marking lines recognized by the external environment recognition unit 11 (in other words, lane marking lines defining the lanes), or the like.

[0022] The stable behavior determination unit 13 determines whether the behavior of the vehicle 1 will become unstable when a relatively large braking force is applied to the vehicle 1 based on the recognition results from the external environment recognition unit 11 (for example, road marking lines, road surface temperature, etc.), the measurement results of the sensors included in the sensor 20 for detecting the motion state of the vehicle 1 (for example, speed, yaw rate and acceleration, etc.), the estimated friction coefficient of the road surface, etc.

[0023] For example, when the lateral grip of the vehicle 1 exceeds the road friction due to at least one of braking and steering of the vehicle 1, the behavior of the vehicle 1 becomes unstable. In particular, when braking and steering of the vehicle 1 are performed simultaneously, the behavior of the vehicle 1 tends to become unstable.

[0024] If a first condition, such as "the steering state quantity associated with vehicle 1 is not less than a first predetermined value," is satisfied, the stable behavior determination unit 13 can determine that the behavior of vehicle 1 will become unstable when a relatively large braking force is applied to vehicle 1. Note that the steering state quantity can be estimated based on the yaw rate, lateral acceleration, steering curvature (i.e., a value obtained by dividing the yaw rate by the speed) of vehicle 1, and the like. Various existing methods can be applied as a method for estimating the steering state quantity, and accordingly, a detailed description thereof will be omitted.

[0025] When the second condition, such as "the estimated friction coefficient of the road surface is not greater than the second predetermined value and / or the road surface temperature is not greater than the third predetermined value" is satisfied, the stable behavior determination unit 13 can determine that the behavior of the vehicle 1 will become unstable when a relatively large braking force is applied to the vehicle 1.

[0026] When a third condition such as "there is a curve with a curvature not less than a fourth predetermined value on the planned route of vehicle 1" is satisfied, the stable behavior determination unit 13 may determine that the behavior of vehicle 1 will become unstable when a relatively large braking force is applied to vehicle 1.

[0027] When one of the first to third conditions is satisfied, the stable behavior determination unit 13 may determine that the behavior of the vehicle 1 will become unstable when a relatively large braking force is applied to the vehicle 1. Alternatively, when multiple of the first to third conditions are satisfied, the stable behavior determination unit 13 may determine that the behavior of the vehicle 1 will become unstable when a relatively large braking force is applied to the vehicle 1.

[0028] When vehicle 1 is about to be decelerated by the aforementioned deceleration assist control, required deceleration calculation unit 14 calculates the required deceleration based on the relative relationship between vehicle 1 and the preceding vehicle (e.g., relative position, relative speed, etc.). For example, the required deceleration may be the deceleration required to bring the relative speed between vehicle 1 and the preceding vehicle to zero within a range of inter-vehicle distances derived from a plurality of relative positions of vehicle 1 and the preceding vehicle. Required deceleration calculation unit 14 further determines whether a collision between vehicle 1 and the preceding vehicle can be avoided by changing the deceleration of vehicle 1 to the calculated deceleration at a predetermined step.

[0029] The warning implementation determination unit 15 determines whether to issue a warning based on, for example, the relative positional relationship between the vehicle 1 and the preceding vehicle, the magnitude of the deceleration calculated by the necessary deceleration calculation unit 14 , and the like.

[0030] The jerk suppression implementation determination unit 16 determines whether the jerk suppression can be relaxed based on at least one of the reliability as an example of the preceding vehicle information calculated by the preceding vehicle information calculation unit 12 , the determination result of the stable behavior determination unit 13 , and the determination result of the necessary deceleration calculation unit 14 .

[0031] Now, "jump suppression" will be described. A limit is set on the jump (i.e., the first-order time derivative of the acceleration) in the above-mentioned deceleration assist control. Accordingly, the fluctuation per time unit of the deceleration (i.e., negative acceleration) when the vehicle 1 is decelerated by the deceleration assist control is suppressed. In the present embodiment, it is assumed that such jump limitation is referred to as "jump suppression". By implementing jump suppression, for example, the stability of the behavior of the vehicle 1 can be improved, and the occupants of the vehicle 1 can be suppressed from feeling uncomfortable. Relaxing jump suppression means relaxing or eliminating the limit placed on the jump.

[0032] The acceleration control unit 17 sends information indicating the physical quantity to be achieved (e.g., braking force, output torque, engine speed, etc.) to one or more components that actually change the behavior of the vehicle 1, such as the braking device 30 of the vehicle 1, the engine control device (which is omitted from the illustration), etc.

[0033] Note that if vehicle 1 is equipped with another system that performs control related to acceleration / deceleration of vehicle 1 in addition to driver assistance device 100, and an arbitration unit is present in vehicle 1 to arbitrate between driver assistance device 100 and the other system, acceleration control unit 17 may transmit information indicating the deceleration requested for the above-described deceleration assist control to the arbitration unit. In this case, the arbitration unit may transmit information indicating the physical quantity to be achieved to one or more components that actually change the behavior of vehicle 1.

[0034] While the deceleration assist control is being executed, the termination determination unit 18 determines whether to terminate the deceleration assist control based on the relative relationship between the vehicle 1 and the preceding vehicle estimated from the recognition result of the external environment recognition unit 11 or the like.

[0035] Next, we will refer to Figure 2 The operation of the driver assistance device 100 is described with reference to a flowchart of FIG.

[0036] exist Figure 2 In the process, the external environment recognition unit 11 recognizes the external environment (step S101). Next, the preceding vehicle information calculation unit 12 calculates the preceding vehicle information based on the recognition result from the external environment recognition unit 11 (step S102).

[0037] In parallel with the processing of step S102, or before or after the processing of step S102, the stable behavior determination unit 13 determines whether the behavior of vehicle 1 will become unstable when a relatively large braking force is applied to vehicle 1 (step S103). Following the processing of step S102, the required deceleration calculation unit 14 calculates the required deceleration based on the relative relationship between vehicle 1 and the vehicle traveling ahead (step S104). At this time, the required deceleration calculation unit 14 determines whether a collision between vehicle 1 and the vehicle traveling ahead can be avoided by changing the deceleration of vehicle 1 to the calculated deceleration while implementing jerk suppression (i.e., with a limit applied to the jerk) and changing the jerk. Next, the alarm implementation determination unit 15 determines whether to issue an alarm (step S105).

[0038] Next, the jerk suppression implementation determination unit 16 determines whether the jerk suppression can be relaxed based on at least one of the reliability of an example of the preceding vehicle information calculated by the preceding vehicle information calculation unit 12, the determination result of the stable behavior determination unit 13, and the determination result of the necessary deceleration calculation unit 14 (step S106).

[0039] When a determination is made in the process of step S106 that jerk suppression can be relaxed ("YES" in step S106), the jerk suppression implementation determination unit 16 transmits a jerk signal indicating that jerk suppression is relaxed to the acceleration control unit 17 without implementing jerk suppression (step S107). Now, examples of cases where a determination is made that jerk suppression can be relaxed include: when the reliability is relatively high and it would be difficult to avoid a collision between the vehicle 1 and the vehicle traveling ahead if jerk suppression is implemented, and when it is determined that the behavior of the vehicle 1 will not become unstable when a relatively large braking force is applied to the vehicle 1.

[0040] When a determination is made in the process of step S106 that jerk suppression cannot be relaxed ("No" in step S106), the jerk suppression implementation determination unit 16 implements jerk suppression and transmits a signal indicating the suppressed jerk to the acceleration control unit 17 (step S108). Now, examples of cases where a determination is made that jerk suppression cannot be relaxed include: when the reliability is relatively high and a collision between the vehicle 1 and the preceding vehicle can be avoided with jerk suppression implemented, and when it is determined that the behavior of the vehicle 1 will become unstable when a relatively large braking force is applied to the vehicle 1.

[0041] In the processing of steps S107 and S108, the jerk indicated by the signal sent from the jerk suppression implementation determination unit 16 to the acceleration control unit 17 may be the jerk when the vehicle 1 is decelerated this time, or may be the jerk limit value. When information indicating the jerk limit value is sent from the jerk suppression implementation determination unit 16 to the acceleration control unit 17, the acceleration control unit 17 can selectively set the acceleration within a range that does not exceed the limit value.

[0042] The acceleration control unit 17 controls the acceleration for decelerating the vehicle 1 based on the jerk indicated by the information sent from the jerk suppression implementation determination unit 16 (step S109). Thereafter, when the end determination unit 18 determines that the deceleration assist control is to be ended, Figure 2 The operation shown in is completed.

[0043] Technical advantages

[0044] When a vehicle ahead decelerates while vehicle 1 is following it using follow-up ACC, driver assistance device 100 decelerates vehicle 1 so that it does not get too close to the vehicle ahead. Driver assistance device 100 automatically decelerates vehicle 1, regardless of the driver's intention. Consequently, since driver assistance device 100 decelerates vehicle 1, jerkiness is suppressed, preventing the driver from feeling uncomfortable.

[0045] For example, when the leading vehicle suddenly decelerates (in other words, brakes suddenly) or when another vehicle cuts in between vehicle 1 and the leading vehicle, even if a collision between vehicle 1 and the leading vehicle is avoidable by using the suppressed jerk, the driver may feel anxious or uncomfortable due to the proximity of vehicle 1 to the leading vehicle or the other vehicle. Note that the other vehicle that has cut in may be considered a new leading vehicle and, accordingly, may be included in the concept of "leading vehicle."

[0046] Accordingly, it is possible to configure vehicle 1 to decelerate when necessary without suppressing jerkiness. However, depending on road conditions, for example, applying a relatively large braking force to vehicle 1 without suppressing jerkiness may cause the behavior of vehicle 1 to become unstable. Conversely, driver assistance device 100 considers the stability of vehicle 1's behavior in addition to the relative relationship between vehicle 1 and the preceding vehicle or another vehicle. Accordingly, driver assistance device 100 can suppress unstable behavior of vehicle 1 due to deceleration assist control.

[0047] While suppressing the jerk associated with deceleration assist control improves the ride comfort of vehicle 1, there's a risk that occupants may experience anxiety as vehicle 1 approaches the vehicle ahead. On the other hand, not suppressing the jerk associated with deceleration assist control does improve the safety of vehicle 1, but there's a risk that occupants may experience discomfort due to the deceleration of vehicle 1 caused by deceleration assist control. The driver assistance device 100 can achieve both improved vehicle 1 safety and an enhanced sense of security for occupants by switching between suppressing and relaxing jerk based on the relative relationship between vehicle 1 and the vehicle ahead, the behavior of vehicle 1, and other factors.

[0048] computer program

[0049] Will refer to Figure 3 Embodiments are described in relation to a computer program. Figure 3 It is a block diagram illustrating the configuration of a computer according to this embodiment.

[0050] exist Figure 3 In the embodiment, a computer 50 is configured to include a central processing unit (CPU) 51, a random-access memory (RAM) 52, a hard disk drive (HDD) 53, and an input / output (I / O) 54. The CPU 51, RAM 52, HDD 53, and I / O 54 are connected to each other via a bus 55. A computer program 531 according to the present embodiment is pre-stored in the HDD 53.

[0051] The processing of the CPU 51, performed by the computer program 531, will now be described. The CPU 51 acquires measurement results obtained by the sensors included in the sensor 20 for identifying the external environment of the vehicle 1. The CPU 51 then identifies the external environment of the vehicle 1. When a preceding vehicle is identified through identification of the external environment, the CPU 51 calculates preceding vehicle information (e.g., reliability) related to the preceding vehicle. The CPU 51 determines whether the behavior of the vehicle 1 will become unstable if a relatively large braking force is applied to the vehicle 1 concurrently with, or before or after, the identification of the external environment.

[0052] The CPU 51 calculates the necessary deceleration based on the relative relationship between the vehicle 1 and the preceding vehicle. At this point, the CPU 51 determines whether a collision between the vehicle 1 and the preceding vehicle can be avoided by changing the deceleration of the vehicle 1 to the calculated deceleration while implementing jerk suppression and varying the jerk. The CPU 51 then determines whether to issue an alarm.

[0053] CPU 51 determines whether the jump suppression can be relaxed based on at least one of the following: (i) the reliability as an example of the preceding vehicle information, (ii) the determination result of whether the behavior of vehicle 1 will become unstable, and (iii) the determination result of whether the collision between vehicle 1 and the vehicle traveling in front can be avoided when the jump suppression is implemented and the jump is changed.

[0054] When it is determined that jerk suppression can be relaxed, the CPU 51 controls the acceleration based on the jerk with jerk suppression relaxed, and decelerates the vehicle 1 without implementing jerk suppression. Conversely, when it is determined that jerk suppression cannot be relaxed, the CPU 51 controls the acceleration based on the suppressed jerk, and decelerates the vehicle 1 while implementing jerk suppression.

[0055] Note that the computer program 531 may be stored in the HDD 53 by the computer 50 reading the computer program 531 from a recording medium such as an optical disk (e.g., a Compact Disc Read-Only Memory (CD-ROM)) or a Universal Serial Bus (USB) memory, which stores the computer program 531. Alternatively, the computer program 531 may be stored in the hard disk drive 53 by the computer 50 downloading the computer program 531 via a network such as the Internet.

[0056] In the same manner as the above-mentioned driver assistance device 100, the computer program 531 is able to achieve both improved safety of the vehicle 1 and improved sense of safety of the occupants by switching between jump suppression and relaxation of the suppression based on the relative relationship between the vehicle 1 and the vehicle traveling in front, the behavior of the vehicle 1, etc.

[0057] Various aspects of the present invention derived from the above-described embodiments will be described below.

[0058] According to one aspect of the present invention, a driver assistance device is a driver assistance device that uses a deceleration means of the own vehicle to automatically decelerate the own vehicle based on the relative relationship between the own vehicle and the vehicle traveling in front of the own vehicle; the driver assistance device includes a control means and an estimation means, the control means is used to change the deceleration of the own vehicle by a first change amount or a second change amount greater than the first change amount when automatically decelerating the own vehicle, and the estimation means is used to estimate whether the behavior of the own vehicle will become unstable when the own vehicle is decelerated by the deceleration means; wherein, the control means changes the deceleration by the first change amount when automatically decelerating the own vehicle when the estimation means estimates that the behavior of the own vehicle is going to become unstable.

[0059] In the above embodiment, the "stable behavior determination unit 13," the "jerk suppression implementation determination unit 16," and the "acceleration control unit 17" correspond to an example of "control means," the "external environment recognition unit 11" corresponds to an example of "estimation means," and the "brake device 30" corresponds to an example of "deceleration means." In the above embodiment, the "jerk when jerk suppression is implemented" corresponds to an example of the "first change amount," and the "jerk when jerk suppression is not implemented" corresponds to an example of the "second change amount." The "own vehicle" is a vehicle equipped with a driver assistance device and is different from the preceding vehicle.

[0060] In the driver assistance device, the estimation means may determine whether the own vehicle is in a predetermined steering state using a sensor that detects the motion state of the own vehicle in at least a part of estimating whether the behavior of the own vehicle will become unstable due to deceleration performed by the deceleration means; and the control means may estimate that the behavior of the own vehicle will become unstable when a determination is made that the own vehicle is in the predetermined steering state, and change the deceleration by the first change amount when automatically decelerating the own vehicle.

[0061] In the driver assistance device, the estimation means estimating whether the behavior of the own vehicle will become unstable due to the deceleration performed by the deceleration means may include estimating the road surface condition of the road on which the own vehicle is traveling; the estimation means may determine whether the behavior of the own vehicle will become unstable due to the deceleration performed by the deceleration means based on one of the following: (i) whether the friction coefficient of the road surface as the road surface condition is not greater than a predetermined value, (ii) whether it is under predetermined weather conditions, and (iii) whether there is a curve in front of the own vehicle.

[0062] According to one aspect of the present invention, a driver assistance method is a driver assistance method of a driver assistance device, which uses a deceleration means of the own vehicle to automatically decelerate the own vehicle based on the relative relationship between the own vehicle and a preceding vehicle traveling in front of the own vehicle, and changes the deceleration of the own vehicle by a first change amount or a second change amount greater than the first change amount when automatically decelerating the own vehicle; and the method includes an estimation process of estimating whether the behavior of the own vehicle will become unstable due to the deceleration performed by the deceleration means, and a control process of changing the deceleration by the first change amount when automatically decelerating the own vehicle when it is estimated in the estimation process that the behavior of the own vehicle is going to become unstable.

[0063] In the driver assistance method, a sensor that detects the motion state of the own vehicle can be used in the estimation process to make a judgment as to whether the own vehicle is in a predetermined steering state as an estimation of whether the behavior of the own vehicle will become unstable due to the deceleration performed by the deceleration means, and when the judgment that the own vehicle is in the predetermined steering state is made in the control process as when it is estimated that the behavior of the own vehicle will become unstable, the deceleration can be changed by the first change amount when automatically decelerating the own vehicle.

[0064] In the driver assistance method, the estimation process may include estimating a road condition of a road on which the vehicle is traveling; the estimation process may determine whether the behavior of the vehicle will become unstable due to the deceleration performed by the deceleration means based on one of the following: (i) whether the friction coefficient of the road surface as the road condition is not greater than a predetermined value, (ii) whether it is under predetermined weather conditions, and (iii) whether there is a curve in front of the own vehicle.

[0065] According to a computer program of one aspect of the present invention, a computer of a driver assistance device is caused to function as a control means and an estimation means, and the driver assistance device uses the deceleration means of the own vehicle to automatically decelerate the own vehicle based on the relative relationship between the own vehicle and the vehicle traveling in front of the own vehicle; the control means is used to change the deceleration of the own vehicle by a first change amount or a second change amount greater than the first change amount when automatically decelerating the own vehicle, and the estimation means is used to estimate whether the behavior of the own vehicle will become unstable due to the deceleration performed by the deceleration means; wherein, when the estimation means estimates that the behavior of the own vehicle is about to become unstable, the control means changes the deceleration by the first change amount when automatically decelerating the own vehicle.

[0066] The present invention is not limited to the above-described embodiments, but may be appropriately modified without departing from the essence or spirit of the invention which can be read from the claims and the entire specification, and driver assistance devices and methods and computer programs having these modifications are also within the technical scope of the present invention.

Claims

1. A driver assistance device, characterized in that comprising a processor, wherein the processor is configured to: automatically decelerating the own vehicle based on a relative relationship between the own vehicle and a preceding vehicle traveling ahead of the own vehicle; changing the deceleration of the own vehicle by a first change amount or a second change amount larger than the first change amount when automatically decelerating the own vehicle; performing a behavior determination to estimate whether the behavior of the own vehicle will become unstable when the own vehicle is automatically decelerated; When it is estimated that the behavior of the own vehicle is about to become unstable, changing the deceleration by the first change amount when automatically decelerating the own vehicle; as well as When it is estimated that the behavior of the own vehicle will not become unstable, the deceleration is changed by the second change amount when automatically decelerating the own vehicle.

2. The driver assistance device according to claim 1, characterized in that The processor is configured as follows: In at least a part of the behavior determination, a sensor that detects a motion state of the own vehicle is used to determine whether the own vehicle is in a predetermined turning state; as well as It is estimated that the behavior of the own vehicle will become unstable when a determination is made that the own vehicle is in the predetermined steering state, and the deceleration is changed by the first change amount when automatically decelerating the own vehicle.

3. The driver assistance device according to claim 1, characterized in that The processor is configured to include, in the behavior determination, estimating a condition of a road on which the own vehicle is traveling; the estimating the condition of the road on which the own vehicle is traveling is determining whether the behavior of the own vehicle will become unstable when the own vehicle is automatically decelerated based on one of the following: (i) whether the friction coefficient of the road surface is equal to or less than a predetermined value, (ii) whether the external environment of the host vehicle is within the predetermined weather conditions, and (iii) Whether there is a curve ahead of the own vehicle.

4. The driver assistance device according to any one of claims 1 to 3, characterized in that The first change amount is a first-order time derivative of acceleration.

5. A driver assistance method for a vehicle, the vehicle being configured to automatically decelerate the vehicle based on a relative relationship between the vehicle and a preceding vehicle that is traveling ahead of the vehicle; and changing the deceleration of the vehicle by a first change amount or a second change amount greater than the first change amount when automatically decelerating the vehicle; characterized in that, The driver assistance method comprises: estimating whether the vehicle's behavior will become unstable when the vehicle automatically decelerates; When it is estimated that the behavior of the vehicle is about to become unstable, changing the deceleration by the first change amount when automatically decelerating the vehicle; and When it is estimated that the behavior of the vehicle will not become unstable, the deceleration is changed by the second change amount when automatically decelerating the vehicle.

6. The driver assistance method according to claim 5, characterized in that: Also includes: Using a sensor that detects a motion state of the vehicle, it is determined whether the vehicle is in a predetermined turning state; wherein the behavior of the vehicle is estimated to become unstable when the determination that the vehicle is in the predetermined turning state is made.

7. The driver assistance method according to claim 5 or 6, characterized in that: The estimating whether the behavior of the vehicle will become unstable when the vehicle is automatically decelerated includes estimating a condition of a road on which the vehicle is traveling; the estimating the condition of the road on which the vehicle is traveling is determining whether the behavior of the vehicle will become unstable when the vehicle is automatically decelerated based on one of the following: (i) whether the friction coefficient of the road surface is not greater than a predetermined value, (ii) whether the external environment of the vehicle is subject to predetermined weather conditions, and (iii) Whether there is a curve ahead of the vehicle.

8. A non-transitory computer-readable storage medium storing a program that, when executed by a processor of a driver assistance device configured to automatically decelerate a vehicle based on a relative relationship between the vehicle and a preceding vehicle traveling ahead of the vehicle, causes the driver assistance device to: changing the deceleration of the vehicle by a first change amount or a second change amount greater than the first change amount when automatically decelerating the vehicle; estimating whether the vehicle's behavior will become unstable when the vehicle automatically decelerates; When it is estimated that the behavior of the vehicle is about to become unstable, changing the deceleration by the first change amount when automatically decelerating the vehicle; as well as When it is estimated that the behavior of the vehicle will not become unstable, the deceleration is changed by the second change amount when automatically decelerating the vehicle.

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