Driving assistance devices

Abstract

To solve a sense of delay when starting following a preceding vehicle.SOLUTION: A driving assistance device is configured such that in a case where a relative relation between a preceding vehicle and own vehicle exceeds a predetermined threshold value when the preceding vehicle starts from a state where the own vehicle is stopped following the preceding vehicle, the own vehicle can start following the preceding vehicle. The driving assistance device determines that a leading vehicle as another vehicle traveling in front of the preceding vehicle is present (step S2), determines whether the leading vehicle has started in a state where the own vehicle is stopped following the preceding vehicle (step S3), and when determining that the leading vehicle has started, reduces the threshold value such that starting of the own vehicle is facilitated (step S4).SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a device that provides assistance to facilitate vehicle driving operations, and more particularly to a driving assistance device that controls the start of a vehicle by following a preceding vehicle. [Background technology]

[0002] When a vehicle travels, it is preferable for it to travel in cooperation with other vehicles traveling in the same direction around it. However, because the flow of vehicles changes due to various factors, it is necessary to accelerate or decelerate in response to these changes. Adaptive cruise control (ACC control) is known as an example of control that reduces such acceleration and deceleration operations. ACC control detects a preceding vehicle using detection means such as radar or lidar, and when there is no preceding vehicle, controls the driving force to maintain a vehicle speed (control vehicle speed) set by the driver. When a preceding vehicle is detected, it controls the driving force while maintaining a predetermined distance from the preceding vehicle. More recently, a control has also been known that stops the host vehicle to follow the preceding vehicle, and when the preceding vehicle starts moving, starts the host vehicle or allows the host vehicle to start moving when the relative relationship between the host vehicle and the preceding vehicle, such as the vehicle speed or the distance between the host vehicle and the preceding vehicle, exceeds a predetermined threshold.

[0003] Patent Document 1 describes a device configured to start a vehicle using so-called tracking control. The device described in Patent Document 1 executes control to stop and start the vehicle by following the stopping and restarting of the preceding vehicle during driving control to follow the preceding vehicle so as to maintain a distance between the preceding vehicle and the vehicle. Specifically, the device described in Patent Document 1 estimates the vehicle speed of the preceding vehicle a predetermined time after start-up based on the vehicle speed and acceleration when the preceding vehicle restarts, and sets a target vehicle speed for resuming following driving based on the estimated vehicle speed and the distance between the preceding vehicle and the vehicle. Then, when the target vehicle speed exceeds a predetermined threshold, the device allows the driver to operate a switch to resume ACC control and starts the vehicle.

[0004] Patent Document 2 also describes a device configured to change a threshold value for determining whether a host vehicle should start. The device described in Patent Document 2 is configured to reflect the behavior of other vehicles traveling parallel to the host vehicle or other vehicles in the oncoming lane in its start control when the host vehicle stops following a preceding vehicle and then starts following the start of the preceding vehicle. More specifically, the device described in Patent Document 2 increases the start threshold value when a vehicle in an adjacent lane is not traveling (stopped) compared to when the vehicle is traveling, and increases the start threshold value when an oncoming vehicle is not traveling (stopped) compared to when the vehicle is traveling. In other words, if a nearby vehicle traveling in the same direction as the host vehicle or an oncoming vehicle traveling in the opposite direction to the host vehicle is stopped, it is predicted that the preceding vehicle will soon stop even if the preceding vehicle is moving. Therefore, by increasing the start threshold value, which is the criterion for determining whether to follow the start of the preceding vehicle, the host vehicle can appropriately follow the slight starts and stops of the preceding vehicle. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2011-240927 [Patent Document 2] Japanese Patent Application Publication No. 2019-84924 Summary of the Invention [Problem to be solved by the invention]

[0006] In the device described in Patent Document 1, the host vehicle is allowed to start when the target vehicle speed exceeds a threshold value. In other words, even if the entire flow of vehicles, including the host vehicle, starts moving, if the preceding vehicle is delayed in starting, the target vehicle speed will not exceed the threshold value, preventing the host vehicle from starting, which causes the driver to feel a sense of delay in starting. In other words, the timing of the host vehicle's start is fixedly limited to the timing determined by the threshold value.

[0007] Furthermore, the device described in Patent Document 2 increases the starting threshold when surrounding vehicles or oncoming vehicles are stopped, thereby avoiding or suppressing a situation in which the host vehicle continues traveling due to the influence of minute movements of the leading vehicle even though the host vehicle is about to stop. However, because the starting threshold is increased, when the host vehicle restarts after stopping, the distance between the host vehicle and the leading vehicle may increase, or the host vehicle may not be able to start until the leading vehicle's speed increases significantly, resulting in a significant delay in starting. Furthermore, the lane on which the surrounding vehicles and oncoming vehicles referenced in the control described in Patent Document 2 are traveling is different from the lane on which the host vehicle is traveling. Therefore, the host vehicle and the surrounding vehicles or oncoming vehicles may have different travel options and travel constraints. In other words, the behavior of surrounding vehicles and oncoming vehicles may not be useful for controlling the host vehicle's departure. As a result, the device described in Patent Document 2 may delay starting or approach the leading vehicle too closely, causing discomfort to the driver.

[0008] This invention has been made with an eye on the above-mentioned technical problems, and aims to provide a driving assistance device that enables a vehicle to start without delay by taking into account the behavior of the vehicle ahead that is traveling in the same lane as the vehicle in question when controlling the start of a vehicle following a preceding vehicle. [Means for solving the problem]

[0009] In order to achieve the above object, the present invention provides a driving assistance device that enables the host vehicle to start following the preceding vehicle when the preceding vehicle starts moving from a stopped state following the preceding vehicle and the relative relationship between the preceding vehicle and the host vehicle exceeds a predetermined threshold value, and is characterized in that the device is configured to determine whether another vehicle, a second preceding vehicle, is present in front of the preceding vehicle, determine whether the second preceding vehicle has started moving while the host vehicle is stopped following the preceding vehicle, and reduce the threshold value to make it easier for the host vehicle to start moving if it is determined that the second preceding vehicle has started moving.

[0010] In this invention, when it is determined that the preceding vehicle is not present in front of the preceding vehicle that the host vehicle is following, the threshold value may be reduced to make it easier for the host vehicle to start moving. [Effects of the Invention]

[0011] In this invention, when the second-first vehicle starts moving from a state in which the host vehicle and the preceding vehicle are stopped, the threshold value for determining whether to start following the preceding vehicle is reduced. Therefore, if the second-first vehicle starts moving, the subsequent forward movement of the preceding vehicle is almost certain to result in the preceding vehicle starting. In this case, the host vehicle starts moving, or can start moving, before the preceding vehicle moves forward and the inter-vehicle distance becomes particularly large, or before the preceding vehicle's speed becomes particularly large. Therefore, according to this invention, it is possible to avoid or suppress a sense of delay when starting following the preceding vehicle.

[0012] Furthermore, if there is no vehicle ahead of the vehicle ahead, the space ahead of the vehicle ahead will be clear, so if the vehicle ahead starts moving from a stopped state, the change in behavior is almost certainly an indication that the vehicle is starting to move. In such cases, too, by reducing the threshold value, it is possible to avoid or suppress the feeling of delay in starting when the host vehicle starts to move following the vehicle ahead. [Brief explanation of the drawings]

[0013] [Figure 1] 1 is a diagram schematically illustrating an example of a vehicle according to an embodiment of the present invention. [Figure 2] FIG. 2 is a block diagram illustrating the functional configuration of the controller. [Figure 3] FIG. 2 is a schematic diagram showing the positional relationship between the host vehicle, a preceding vehicle, and a vehicle ahead of the preceding vehicle when stopped; [Figure 4] 3 is a flowchart illustrating an example of control executed in the embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0014] Next, an embodiment of the present invention will be described with reference to the drawings. Note that the embodiment described below is merely an example of how the present invention can be implemented, and is not intended to limit the present invention.

[0015] A vehicle in an embodiment of the present invention is configured to travel while maintaining a distance from the vehicle ahead that is immediately ahead of it that is equal to or greater than a preset distance, and when the vehicle ahead stops, to stop while maintaining a predetermined distance, and when the vehicle ahead starts moving, to start moving after the vehicle ahead. One example of this type of travel control is a conventionally known control called adaptive cruise control (ACC control). Therefore, as shown schematically in Fig. 1, vehicle 1 includes a controller 2 that performs ACC control, a power controller (PCU) 3 that controls the driving force or braking force of vehicle 1 based on a control signal from controller 2, a radar sensor 4 that detects the vehicle ahead and the surrounding conditions, and the like.

[0016] Controls such as ACC control, which maintains a predetermined distance or greater between the vehicle and the preceding vehicle while driving, may be similar to, for example, the vehicle stop / start control described in Patent Document 2, or conventionally known constant speed cruise control or ACC control. That is, a set vehicle speed (or control vehicle speed), which is a target vehicle speed during driving, and a vehicle distance (set vehicle distance) between the preceding vehicle and the preceding vehicle are manually input, and if the distance between the preceding vehicle is equal to or greater than the set vehicle distance, the driving force is controlled so that the vehicle speed becomes equal to the set vehicle speed. Furthermore, if the distance between the preceding vehicle and the preceding vehicle becomes shorter than the set vehicle distance due to another vehicle cutting in, the vehicle decelerates to increase the distance between the preceding vehicle and the preceding vehicle. Furthermore, in an embodiment of the present invention, when the preceding vehicle stops due to a stop signal or the like, the vehicle decelerates and approaches the vehicle distance at the time of stopping to stop the vehicle. Then, when the preceding vehicle starts moving, the vehicle starts moving after following the preceding vehicle when the relative relationship determined by the vehicle distance, the vehicle speed, and the like exceeds a predetermined threshold.

[0017] The vehicle is provided with devices and systems for detecting data used for such driving control. The vehicle is equipped with a navigation system (NAV) 5 that acquires data such as the vehicle's position and driving environment. The NAV 5 is a conventionally known system that determines the vehicle's position and destination on a map by referencing a position calculated using signals from GPS satellites, autonomous navigation using a gyroscope, and a pre-prepared map. The NAV 5 is preferably configured to be compatible with VICS (registered trademark), and is preferably configured to acquire road information or environmental information around or in the vicinity of the vehicle using FM multiplex broadcasting, radio beacons, or optical beacons.

[0018] Furthermore, in order to drive in coordination with other vehicles around the vehicle, the vehicle is equipped with an inter-vehicle communication system 6 that acquires data about the other vehicles from the other vehicles. The data acquired by the inter-vehicle communication system 6 includes, for example, the speed, acceleration and deceleration, driving direction, and current position of the other vehicles.

[0019] The radar sensor 4 is a sensor for detecting vehicles ahead of the host vehicle, structures such as road facilities, obstacles, and pedestrians, and may include a millimeter-wave radar sensor, a lidar sensor, or the like. In the embodiment of the present invention, in addition to data on a preceding vehicle immediately ahead of the host vehicle, data on a vehicle immediately ahead of the preceding vehicle (i.e., a vehicle two vehicles ahead of the host vehicle) is also acquired. The data on the vehicle two vehicles ahead may be the same as the data on the preceding vehicle, but is particularly data on the start and stop of the vehicle two vehicles ahead. This data is acquired by the NAV 5, the radar sensor 4, or the vehicle-to-vehicle communication system 6 described above.

[0020] When performing assist control related to vehicle speed such as ACC control, the controller 2 is configured to calculate a target vehicle speed, determine whether to stop or start, and calculate a stopping position based on data acquired by the above-mentioned radar sensor 4, NAV 5, or vehicle-to-vehicle communication system 6, and output the results as a control command signal to the PCU 3. As in a vehicle equipped with conventional ACC control, the PCU 3 controls a driving force source including an engine, a motor, and a transmission mechanism based on the input control command signal to maintain the vehicle speed at a set vehicle speed, decelerate or accelerate the vehicle depending on the distance to the preceding vehicle, and stop or start the vehicle. Note that starting the vehicle may require a driver's operation such as a switch operation.

[0021] The controller 2 that performs the above control is an electronic control device primarily configured with a microcomputer including arithmetic elements, memory elements, and input / output interfaces. A functional configuration for performing control in an embodiment of the present invention is shown in FIG. 2. As described above, the driving assistance device of the embodiment described here controls vehicle speed, starting, and stopping based on the relative relationship between the preceding vehicle immediately before the host vehicle and the vehicle immediately preceding the preceding vehicle. Therefore, the controller 2 includes a preceding vehicle information acquisition unit 2A and a preceding vehicle information acquisition unit 2B. The information acquired by these information acquisition units 2A and 2B is data obtained from the radar sensor 4, NAV 5, or vehicle-to-vehicle communication system 6. The preceding vehicle information acquisition unit 2A acquires, as control data, information such as the presence or absence of a preceding vehicle, the distance between the preceding vehicle and the preceding vehicle, and the vehicle speed of the preceding vehicle. The preceding vehicle information acquisition unit 2B acquires, as data, information such as the presence or absence of a preceding vehicle, its stopping and starting. Therefore, in this embodiment of the present invention, this preceding vehicle information acquisition unit 2B corresponds to a function or means for determining whether a preceding vehicle exists, and a function or means for determining whether the preceding vehicle has started moving.

[0022] The vehicle is equipped with a start threshold changing unit 2C that changes a threshold value (start threshold value) for determining whether the host vehicle has started. When the host vehicle stops following a preceding vehicle and then starts following the preceding vehicle, it is necessary to determine whether the preceding vehicle has started, and the start threshold value is a threshold value for this determination. The threshold value includes a threshold value for the inter-vehicle distance and a threshold value for the vehicle speed. The threshold value for the inter-vehicle distance is predetermined by design to prevent rear-end collisions or excessive closeness. The threshold value for the vehicle speed is a threshold value for determining whether the preceding vehicle has not simply moved forward but is gradually accelerating, i.e., has actually started, and is predetermined by design. Note that other data, such as the duration of the preceding vehicle's forward movement, may also be added to determine whether the preceding vehicle has started, and in that case, threshold values ​​for the other data would also be set. Setting the start threshold value to a large value can avoid or suppress rear-end collisions, contact, or excessive closeness, but it will result in the host vehicle starting later than the preceding vehicle's start. The start threshold value is set taking these circumstances into consideration, but in this embodiment of the present invention, the start threshold value is shortened based on the status of the vehicle ahead, and the start threshold value changing unit 2C changes the start threshold value. The change is made when it is determined that a vehicle ahead exists and has started moving, and therefore the start threshold value changing unit 2C corresponds to the function or means for shortening the threshold value in this embodiment of the present invention.

[0023] Furthermore, the vehicle control system is provided with a start determination unit 2D that determines whether to start the host vehicle that is stopped following a preceding vehicle. This determination is the same as that in normal ACC control, and the host vehicle is started or permitted to start when the inter-vehicle distance to the preceding vehicle exceeds a threshold value or the vehicle speed of the preceding vehicle exceeds a threshold value. A start instruction unit 2E is further provided that instructs the PCU 3 to start the host vehicle when the start determination unit 2D determines that the host vehicle should start.

[0024] Next, an example of control according to an embodiment of the present invention will be described. Fig. 3 schematically shows a state in which a group of vehicles including the host vehicle M0 are stopped at a red light Sr, and Fig. 4 shows a flowchart for explaining an example of control executed in this case. The host vehicle M0 is stopped in the left lane of a two-lane road, and ahead of the host vehicle M0, a preceding vehicle M1 and a vehicle M2 ahead of the host vehicle M0 are stopped side by side. In addition, other vehicles M3, M4, M5, etc. are stopped side by side in the right lane near the center. In this state, the host vehicle M0 acquires data, such as that it is stopped at the red light Sr, that the preceding vehicle M1 and the vehicle M2 ahead of the host vehicle M0 are stopped, and that the inter-vehicle distance Gv between the host vehicle M0 and the preceding vehicle M1 is a predetermined distance, using the radar sensor 4, NAV 5, or vehicle-to-vehicle communication system 6 described above.

[0025] In this stopped state, the control shown in Fig. 4 is executed. First, it is determined whether the host vehicle M0 is stopped in accordance with the preceding vehicle M1 (step S1). If the determination in step S1 is negative, the routine shown in Fig. 4 is temporarily terminated without any particular control being performed. Conversely, if the determination in step S1 is positive, it is determined whether the second preceding vehicle M2 is present (step S2). If the determination in step S2 is positive because the second preceding vehicle M2 is present, it is determined whether the second preceding vehicle M2 has started moving (step S3). The determination of the start of the vehicle may be made based on whether the forward speed of the second preceding vehicle M2 is equal to or greater than a predetermined vehicle speed, whether the second preceding vehicle M2 has simply moved forward, or whether the forward distance has exceeded a predetermined value.

[0026] If the answer to step S3 is affirmative because the second preceding vehicle M2 has started, the threshold value (start threshold value) for determining whether the host vehicle M0 has started is reduced (lowered) (step S4). The reduction amount may be a predetermined amount in design. Conversely, if the answer to step S3 is negative, the threshold value (start threshold value) is not changed but is maintained at a preset value (step S5).

[0027] Next, it is determined whether the relationship between the preceding vehicle M1 and the host vehicle M0, such as the inter-vehicle distance from the preceding vehicle M1 and the vehicle speed of the preceding vehicle M1, exceeds the above-mentioned departure threshold (step S6). In other words, it is determined whether the preceding vehicle M1 has moved forward and the host vehicle M0 is ready to start. Note that if the inter-vehicle distance and vehicle speed have been detected, the condition for the host vehicle M0 to start in step S6 can be that both the inter-vehicle distance and the vehicle speed exceed the departure threshold. However, as described above, if it has already been determined that the vehicle M2 ahead of the preceding vehicle M2 has started, the condition for the host vehicle M0 to start can also be that only one of the inter-vehicle distance or the vehicle speed exceeds the departure threshold.

[0028] If the determination in step S6 is affirmative, a command to start or permission to start is output (step S7). Conversely, if the determination in step S6 is negative, the command to start or permission to start is not output, and the stopped state is maintained (step S8).

[0029] Therefore, in the above control, when the preceding vehicle M1 that the host vehicle M0 is following starts moving and the relationship with the host vehicle M0, such as the inter-vehicle distance, exceeds the start threshold, the host vehicle M0 starts or is permitted to start. In this case, if the second-to-first vehicle M2 has started moving, the start threshold is small, so when the preceding vehicle M1 starts moving, the inter-vehicle distance and the like exceed the start threshold in a short period of time, thereby eliminating or shortening the delay in the start of the host vehicle M0. In other words, the feeling of a delay in starting can be eliminated. In particular, a driving assistance device configured to perform the above control controls the start of the host vehicle M0 based on the behavior of the preceding vehicle M1 and the second-to-first vehicle M2 in the same lane as the host vehicle M0, thereby enabling appropriate start control. For example, in the situation shown in Figure 3, if starting control is performed by referring to the behavior of vehicles M3 to M5 in adjacent lanes as the behavior of surrounding vehicles, if the lane of vehicle M0 remains stopped due to a vehicle turning left and vehicles are flowing smoothly in the adjacent right lane, starting control will be performed based on the behavior of other vehicles that are not related to the starting of vehicle M0, and there is a possibility that vehicle M0 will stop immediately after starting or will get too close to leading vehicle M1.

[0030] 4, similar to the control in step S4 described above, the threshold value (start threshold value) for determining whether to start the host vehicle M0 is reduced (step S9). If there is no vehicle M2 ahead of the host vehicle M1, it is considered normal for the preceding vehicle M1 to start moving forward and continue traveling, so a slight movement of the preceding vehicle M1 is used to determine whether to start the host vehicle M0, enabling a quick start. [Explanation of symbols]

[0031] 1 vehicle 2 Controller 2A Leading vehicle information acquisition unit 2B Preceding vehicle information acquisition unit 2C Threshold value change section 2D start determination unit 2E Departure indicator 3 Power Control Unit (PCU) 4 Radar Sensor 5 Navigation system (NAV) 6 Vehicle-to-vehicle communication system M0 Vehicle M1 Leading vehicle M2 Next preceding vehicle

Claims

1. 1. A driving assistance device that enables a host vehicle to start following a preceding vehicle when the preceding vehicle starts moving from a stopped state following the preceding vehicle and a relative relationship between the preceding vehicle and the host vehicle exceeds a predetermined threshold, determining whether a second preceding vehicle is present ahead of the preceding vehicle; determining whether the preceding vehicle has started moving while the host vehicle is stopped following the preceding vehicle; When it is determined that the preceding vehicle has started, the threshold value is reduced so that the host vehicle can start more easily. A driving assistance device characterized by:

2. The driving assistance device according to claim 1, A driving assistance device characterized in that, when it is determined that the preceding vehicle is not present in front of the preceding vehicle that the subject vehicle is following, the threshold value is reduced to make it easier for the subject vehicle to start moving.

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