Vehicle driving assistance system, vehicle driving assistance method, and vehicle driving assistance program

Abstract

To provide a vehicle driving support device which can make an own vehicle perform autonomous travel through autonomous travel control without obstructing smooth traffic of peripheral vehicles even when no following vehicle is found.SOLUTION: A vehicle driving support device 10 can execute: increase / decrease control of vehicle speed where an own vehicle performs autonomous travel while increasing and decreasing vehicle speed of the own vehicle 100 within a specified vehicle speed range; and increase / decrease control of vehicular gap where the own vehicle performs autonomous travel while increasing and decreasing a vehicular gap between the own vehicle and the other vehicle in the periphery of the own vehicle within a specified vehicular gap range or increasing and decreasing time required for traveling of the own vehicle among the vehicular gap within a specified time range. The vehicle driving support device makes, when a following vehicle detection device 52 detecting a following vehicle 300 has an abnormality so as to satisfy a control range change condition during execution of the increase / decrease control of vehicle speed or the increase / decrease control of vehicular gap, the specified vehicle speed range or the specified vehicular gap range be a smaller range in comparison with a case that the control range change condition is not satisfied.SELECTED DRAWING: Figure 11

Description

Technical Field

[0001] The present invention relates to a vehicle driving support device, a vehicle driving support method, and a vehicle driving support program.

Background Art

[0002] There is known a vehicle driving support device that executes autonomous driving control to drive a host vehicle by autonomously controlling the operation of a power unit of the host vehicle so that the vehicle speed of the host vehicle increases or decreases within a set vehicle speed range or the inter-vehicle distance between the host vehicle and a preceding vehicle increases or decreases within a set inter-vehicle distance range (see, for example, Patent Document 1). By driving the host vehicle by the above autonomous driving control, the vehicle driving support device aims to reduce the amount of energy consumed (energy consumption amount) in the power unit.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

[0004] When a following vehicle exists during the execution of the above autonomous driving control, if the vehicle speed of the host vehicle increases or decreases excessively or the inter-vehicle distance between the host vehicle and the preceding vehicle increases or decreases excessively, the following vehicle will increase or decrease its vehicle speed significantly, which may interfere with the smooth traffic of surrounding vehicles including the following vehicle. Therefore, in order to maintain the smooth traffic of surrounding vehicles, when a following vehicle exists during the execution of the above autonomous driving control, it is desirable to execute the autonomous driving control in consideration of the existence of the following vehicle.

[0005] However, for this purpose, it is necessary to detect the following vehicle by a detection device. If an abnormality occurs in the detection device and the following vehicle cannot be detected, the autonomous driving control cannot be executed in consideration of the existence of the following vehicle. Therefore, the autonomous driving control cannot be executed so as to maintain the smooth traffic of surrounding vehicles.

[0006] The object of the present invention is to provide a vehicle driving support device, a vehicle driving support method, and a vehicle driving support program that enable the vehicle to drive autonomously through autonomous driving control without interfering with the smooth flow of traffic of surrounding vehicles, even when it is not possible to detect a following vehicle.

[0007] The vehicle driving assistance device according to the present invention includes a control device configured to perform speed increase / decrease control, which causes the vehicle to autonomously drive while increasing or decreasing the vehicle speed of the vehicle within a set speed range, or inter-vehicle distance increase / decrease control, which causes the vehicle to autonomously drive while increasing or decreasing the distance between the vehicle and other vehicles in the vicinity of the vehicle within a set inter-vehicle distance range, or while increasing or decreasing the time required for the vehicle to travel the inter-vehicle distance within a set time range. Furthermore, the control device is configured to set the set speed range or the set inter-vehicle distance range to a smaller range than when the control range change condition is not met, if a control range change condition is met, such as an abnormality in the following vehicle detection device that detects following vehicles, while the speed increase / decrease control or the inter-vehicle distance increase / decrease control is being executed.

[0008] When a vehicle is autonomously driven using speed adjustment or distance adjustment control, if there is a following vehicle, and the vehicle's speed or the distance between the vehicle and other vehicles around it changes excessively, the following vehicle may also change its speed significantly, potentially hindering the smooth flow of traffic for surrounding vehicles, including the following vehicle. Therefore, in order to maintain the smooth flow of traffic for surrounding vehicles, when a vehicle is autonomously driven using speed adjustment or distance adjustment control and there is a following vehicle, it is desirable to take the presence of the following vehicle into consideration when performing the autonomous driving using speed adjustment or distance adjustment control. However, in order to do so, it is necessary to detect following vehicles using a following vehicle detection device. If a malfunction occurs in the following vehicle detection device and it is not possible to detect following vehicles, it will not be possible to perform speed increase / decrease control or following distance increase / decrease control while taking the presence of following vehicles into consideration. Consequently, it will not be possible to autonomously drive the vehicle by performing speed increase / decrease control or following distance increase / decrease control in order to maintain smooth traffic flow for surrounding vehicles.

[0009] According to the vehicle driving assistance system of the present invention, if an abnormality occurs in the following vehicle detection device, the set vehicle speed range or the set following distance range is set to a smaller range than when the following vehicle detection device is functioning normally. As a result, the vehicle speed of the vehicle itself and the following distance between the vehicle and the preceding vehicle are maintained within a narrow range, thereby preventing the vehicle speed from increasing or decreasing excessively, or the following distance between the vehicle and the preceding vehicle from increasing or decreasing excessively. Therefore, even when a following vehicle cannot be detected, the vehicle can be driven autonomously by autonomous driving control without interfering with the smooth flow of traffic of surrounding vehicles.

[0010] Furthermore, in the vehicle driving support device according to the present invention, the control device may be configured to perform speed maintenance control, which autonomously drives the vehicle while maintaining the vehicle speed at a set speed, or distance maintenance control, which autonomously drives the vehicle while maintaining the distance between vehicles at a set distance or while maintaining the time required for the vehicle to travel the distance between vehicles at a set time. In this case, the control device may be configured to stop the speed maintenance control and execute the speed maintenance control if, during the execution of the speed increase / decrease control, the following vehicle detection device is functioning correctly, a following vehicle is detected, and the distance between the following vehicle and the vehicle is less than or equal to a predetermined distance, or the time required for the vehicle to travel the distance between the following vehicle and the vehicle is less than or equal to a predetermined time, and if, during the execution of the distance maintenance control, the following vehicle maintenance control and execute the distance maintenance control may be stopped.

[0011] When a vehicle is autonomously driven using speed adjustment control or distance adjustment control, if there is a following vehicle, and the vehicle's speed or the distance between the vehicle and the preceding vehicle changes excessively, the following vehicle may also change its speed significantly, potentially hindering the smooth flow of traffic for surrounding vehicles, including the following vehicle.

[0012] According to the vehicle driving assistance system of the present invention, when a following vehicle is relatively close to the vehicle, that is, when the driving mode switching condition is met, the vehicle speed increase / decrease control or the following distance increase / decrease control is discontinued and vehicle speed maintenance control or following distance maintenance control is executed. As a result, the vehicle speed of the vehicle is maintained at a constant level, and the following distance between the vehicle and the preceding vehicle is maintained at a constant level. Therefore, even when a following vehicle is relatively close to the vehicle, the vehicle can be driven autonomously in a way that maintains smooth traffic flow for surrounding vehicles.

[0013] Furthermore, in the vehicle driving support device according to the present invention, the control device may be configured to perform vehicle speed increase / decrease control or inter-vehicle distance increase / decrease control in a first drive mode in which power is applied to the vehicle by operating both the internal combustion engine and the electric motor or only the internal combustion engine to drive the vehicle, and in a second drive mode in which power is applied to the vehicle by operating only the electric motor to drive the vehicle. In this case, the set vehicle speed range is set to be smaller when the vehicle speed increase / decrease control is performed in the second drive mode than when the vehicle speed increase / decrease control is performed in the first drive mode. Also, the set inter-vehicle distance range is set to be smaller when the inter-vehicle distance increase / decrease control is performed in the second drive mode than when the inter-vehicle distance increase / decrease control is performed in the first drive mode. Furthermore, the control range change condition includes, for example, the condition that the vehicle speed increase / decrease control or the inter-vehicle distance increase / decrease control is being performed in the first drive mode. Furthermore, when the control device is performing the vehicle speed increase / decrease control or the inter-vehicle distance increase / decrease control in the second drive mode, it may be configured not to change the set vehicle speed range or the set inter-vehicle distance range even if the control range change condition is met.

[0014] According to the vehicle driving assistance system of the present invention, when the vehicle is autonomously driving in the second drive mode by vehicle speed increase / decrease control or inter-vehicle distance increase / decrease control, the set vehicle speed range or set inter-vehicle distance range is set to a relatively small range. Therefore, even in situations where a following vehicle cannot be detected due to a malfunction in the following vehicle detection device, if the autonomous driving of the vehicle continues by vehicle speed increase / decrease control or inter-vehicle distance increase / decrease control without changing the set vehicle speed range or set inter-vehicle distance range, the vehicle speed of the vehicle will not increase or decrease excessively, nor will the distance between the vehicle and the preceding vehicle increase or decrease excessively, and therefore the following vehicle will not increase or decrease its speed significantly. For this reason, the possibility of hindering the smooth traffic of surrounding vehicles is small. Therefore, the vehicle can be autonomously driven by vehicle speed increase / decrease control or inter-vehicle distance increase / decrease control in such a way that the smooth traffic of surrounding vehicles is maintained, without changing the set vehicle speed range or set inter-vehicle distance range.

[0015] Furthermore, in the vehicle driving support device according to the present invention, the control device may be configured to selectively execute power control in a first state in which power generation loss in the vehicle's power unit or power transmission loss from the power unit to the vehicle's drive wheels is reduced, and power control in a second state in which the power unit is mechanically or electrically connected to the drive wheels to apply power to the drive wheels, thereby enabling the execution of vehicle speed increase / decrease control or inter-vehicle distance increase / decrease control. In this case, when the control device is executing vehicle speed increase / decrease control or inter-vehicle distance increase / decrease control while selectively executing the power control in the first state and the power control in the second state, and the control range change condition is not met, the control device may be configured to set the set vehicle speed range or set inter-vehicle distance range to a larger range than when the vehicle is autonomously driven by vehicle speed increase / decrease control or inter-vehicle distance increase / decrease control in the first drive mode.

[0016] When autonomous driving control is performed, that is, when the vehicle is driven autonomously by controlling the vehicle speed or the distance between vehicles while selectively performing power control in the first state and power control in the second state, if the set vehicle speed range or set distance between vehicles is set to a large range when the vehicle is driven autonomously in the first drive mode, the effect of reducing energy consumption is generally greater. However, when the vehicle is driven autonomously in the second drive mode, even if the set vehicle speed range or set distance between vehicles is set to a large range, the effect of reducing energy consumption is not so great, but the risk of hindering the smooth flow of traffic for surrounding vehicles increases.

[0017] According to the vehicle driving assistance device of the present invention, when the vehicle is autonomously driven by vehicle speed increase / decrease control or inter-vehicle distance increase / decrease control while selectively executing power control in a first state and power control in a second state, and the control range change condition is not met, if the drive mode is the first drive mode, the set vehicle speed range or set inter-vehicle distance range is set to a larger range than if the drive mode were the second drive mode. Therefore, it is possible to obtain a certain reduction in energy consumption depending on the drive mode while suppressing interference with the smooth traffic flow of surrounding vehicles.

[0018] Furthermore, the vehicle driving assistance method according to the present invention is a method for performing vehicle speed increase / decrease control, which causes the vehicle to autonomously drive while increasing or decreasing the vehicle speed of the vehicle within a set vehicle speed range, or inter-vehicle distance increase / decrease control, which causes the vehicle to autonomously drive while increasing or decreasing the inter-vehicle distance between the vehicle and other vehicles in the vicinity within a set inter-vehicle distance range, or while increasing or decreasing the time required for the vehicle to travel the inter-vehicle distance within a set time range. The vehicle driving assistance method according to the present invention further includes a step of setting the set vehicle speed range or the set inter-vehicle distance range to a smaller range than when the control range change condition is not met, if a control range change condition is met, such as an abnormality in the following vehicle detection device that detects following vehicles, while the vehicle speed increase / decrease control or the inter-vehicle distance increase / decrease control is being performed.

[0019] According to the vehicle driving assistance method of the present invention, for the same reasons as described above, even when it is not possible to detect a following vehicle, the vehicle can be driven autonomously by autonomous driving control without interfering with the smooth flow of traffic of surrounding vehicles.

[0020] Furthermore, the vehicle driving support program according to the present invention is a program that executes vehicle speed increase / decrease control for autonomously driving the host vehicle while increasing or decreasing the vehicle speed of the host vehicle within a set vehicle speed range, or inter-vehicle distance increase / decrease control for autonomously driving the host vehicle while increasing or decreasing the inter-vehicle distance between the host vehicle and other vehicles around the host vehicle within a set inter-vehicle distance range or while increasing or decreasing the time required for the host vehicle to travel the inter-vehicle distance within a set time range. And, the vehicle driving support program according to the present invention is configured to set the set vehicle speed range or the set inter-vehicle distance range to a smaller range when a control range change condition indicating that there is an abnormality in a following vehicle detection device for detecting a following vehicle is satisfied during the execution of the vehicle speed increase / decrease control or the inter-vehicle distance increase / decrease control, compared to when the control range change condition is not satisfied.

[0021] According to the vehicle driving support program of the present invention, for the same reasons as described above, even when a following vehicle cannot be detected, the host vehicle can be autonomously driven by autonomous driving control without disturbing the smooth traffic of surrounding vehicles.

[0022] The components of the present invention are not limited to the embodiments of the present invention described below with reference to the drawings. Other objects, other features, and attendant advantages of the present invention will be easily understood from the description of the embodiments of the present invention.

Brief Description of the Drawings

[0023] [Figure 1] FIG. 1 is a diagram showing a vehicle driving support device according to an embodiment of the present invention. [Figure 2] (A) of FIG. 2 is a diagram showing a scene where a preceding vehicle exists in front of the host vehicle, and (B) of FIG. 2 is a diagram showing a scene where no preceding vehicle exists in front of the host vehicle. [Figure 3] (A) of FIG. 3 is a diagram showing a scene where no preceding vehicle exists in front of the host vehicle and a following vehicle exists behind the host vehicle, and (B) of FIG. 3 is a diagram showing a scene where a preceding vehicle exists in front of the host vehicle and a following vehicle exists behind the host vehicle. [Figure 4]FIG. 4 is a flowchart showing a routine executed by a vehicle driving support device according to an embodiment of the present invention. [Figure 5] FIG. 5 is a flowchart showing a routine executed by a vehicle driving support device according to an embodiment of the present invention. [Figure 6] FIG. 6 is a flowchart showing a routine executed by a vehicle driving support device according to an embodiment of the present invention. [Figure 7] FIG. 7 is a flowchart showing a routine executed by a vehicle driving support device according to an embodiment of the present invention. [Figure 8] FIG. 8 is a time chart showing changes in road gradient and own vehicle speed when eco autonomous driving control ends and normal vehicle speed control is executed. [Figure 9] FIG. 9 is a time chart showing changes in road gradient and own vehicle speed when normal vehicle speed control is executed after coasting control is executed after eco autonomous driving control ends. [Figure 10] FIG. 10 is a flowchart showing a routine executed by a vehicle driving support device according to an embodiment of the present invention. [Figure 11] FIG. 11 is a flowchart showing a routine executed by a vehicle driving support device according to an embodiment of the present invention. [Figure 12] FIG. 12 is a flowchart showing a routine executed by a vehicle driving support device according to an embodiment of the present invention. [Figure 13] FIG. 13 is a flowchart showing a routine executed by a vehicle driving support device according to an embodiment of the present invention.

Embodiments for Carrying Out the Invention

[0024] Hereinafter, with reference to the drawings, a vehicle driving support device, a vehicle driving support method, and a vehicle driving support program according to embodiments of the present invention will be described. Figure 1 shows the vehicle driving support device 10. The vehicle driving support device 10 is mounted on the vehicle 100. Hereinafter, the vehicle driving support device 10 will be described using the case where the operator of the vehicle 100 is a person who is riding in the vehicle 100 and driving the vehicle 100 (i.e., the driver of the vehicle 100) as an example.

[0025] However, the operator of the vehicle 100 may be a person who operates the vehicle 100 remotely without being in the vehicle 100 (i.e., a remote operator of the vehicle 100). If the operator of the vehicle 100 is a remote operator, the vehicle driving support device 10 is installed in the vehicle 100 and in the remote control equipment installed outside the vehicle 100 for remote operation of the vehicle 100, and the functions of the vehicle driving support device 10 described below are shared between the vehicle driving support device 10 installed in the vehicle 100 and the vehicle driving support device 10 installed in the remote control equipment.

[0026] As shown in Figure 1, the vehicle driving assistance system 10 includes an ECU (Electronic Control Unit) 90 as a control device. The ECU 90 mainly consists of a microcomputer. The microcomputer includes a CPU, ROM, RAM, non-volatile memory and other storage media, as well as interfaces. The CPU realizes various functions by executing instructions, programs, or routines stored in the storage media. In particular, in this example, the vehicle driving assistance system 10 stores programs that realize the various controls that the vehicle driving assistance system 10 performs in the storage media.

[0027] Furthermore, the vehicle driving assistance device 10 may be configured to update the program stored on the recording medium via wireless communication with an external device (for example, internet communication).

[0028] As shown in Figure 1, the vehicle 100 is equipped with a power unit 20 and a braking unit 30. The power unit 20 is a device that generates power supplied to the vehicle 100 (particularly the drive wheels of the vehicle 100), and in this example, it comprises an internal combustion engine 21 and an electric motor 22. The braking unit 30 is a device that applies braking force to the vehicle 100 (particularly the wheels of the vehicle 100), and in this example, it comprises a hydraulic brake system 31. The internal combustion engine 21, the electric motor 22, and the hydraulic brake system 31 are electrically connected to the ECU 90. The vehicle driving support system 10 can control the operation of the internal combustion engine 21, the electric motor 22, and the hydraulic brake system 31.

[0029] Furthermore, the vehicle 100 is equipped with an energy storage device 41 such as a battery and a charge level sensor 42. The electric motor 22 is operated by the power stored in the energy storage device 41. The electric motor 22 also generates electricity from the power output from the internal combustion engine 21 and charges the energy storage device 41 with the generated electricity. The charge level sensor 42 is a sensor that detects the amount of electricity stored in the energy storage device 41. The charge level sensor 42 is electrically connected to the ECU 90. The vehicle driving support system 10 detects the amount of electricity stored in the energy storage device 41 using the charge level sensor 42.

[0030] Furthermore, the vehicle 100 is equipped with a surrounding information detection device 50. The surrounding information detection device 50 is a device that acquires information about the surroundings of the vehicle 100 as surrounding information detection information IS. In this example, the surrounding information detection device 50 includes a forward information detection device 51 and a rear information detection device 52.

[0031] The forward information detection device 51 includes a forward electromagnetic wave sensor 511 such as a radar sensor and a forward image sensor 512 such as a camera sensor. The forward electromagnetic wave sensor 511 and the forward image sensor 512 are electrically connected to the ECU 90. The vehicle driving support device 10 acquires data on targets in front of the vehicle 100 (forward target information IF_O) using the forward electromagnetic wave sensor 511 as forward detection information IF. The vehicle driving support device 10 also acquires image data of the area in front of the vehicle 100 (forward image information IF_C) using the forward image sensor 512 as forward detection information IF.

[0032] The vehicle driving support system 10 detects the preceding vehicle 200 based on the forward target information IF_O and / or forward image information IF_C, and further acquires the preceding vehicle distance DF. The preceding vehicle 200 is another vehicle traveling ahead of the own vehicle 100 at a distance within a predetermined distance from the own vehicle 100, as shown in Figure 2(A), and is traveling in the own vehicle's driving lane LN1. The preceding vehicle distance DF is the distance (inter-vehicle distance) between the own vehicle 100 and the preceding vehicle 200.

[0033] Furthermore, the rear information detection device 52 is equipped with a rear electromagnetic wave sensor 521 such as a radar sensor and a rear image sensor 522 such as a camera sensor. The rear electromagnetic wave sensor 521 and the rear image sensor 522 are electrically connected to the ECU 90. The vehicle driving support device 10 acquires data on targets behind the vehicle 100 (rear target information IR_O) as rear detection information IR using the rear electromagnetic wave sensor 521. The vehicle driving support device 10 also acquires image data of the area behind the vehicle 100 (rear image information IR_C) as rear detection information IR using the rear image sensor 522.

[0034] The vehicle driving support system 10 detects the following vehicle 300 based on the rear target information IR_O and / or the rear image information IR_C, and further acquires the following vehicle distance DR. The following vehicle 300 is another vehicle traveling behind the vehicle 100 at a predetermined distance from the vehicle 100, as shown in Figures 3(A) and (B), and is traveling in the vehicle's driving lane LN1. The following vehicle distance DR is the distance (inter-vehicle distance) between the vehicle 100 and the following vehicle 300.

[0035] <Overview of the operation of the vehicle's driver assistance system> Next, we will explain the overview of the operation of the vehicle driving assistance system 10.

[0036] The vehicle driving support device 10 is configured to perform autonomous driving control (e.g., eco-speed control or eco-distance control, described later) that autonomously drives the vehicle 100 in a first driving mode by selectively executing power control in a first state in which power generation loss in the power unit 20 or power transmission loss from the power unit 20 to the drive wheels is reduced (e.g., coasting control, described later), and power control in a second state in which the power unit 20 is mechanically or electrically connected to the drive wheels and power is applied to the drive wheels (e.g., optimal traction control, described later), thereby increasing or decreasing the control value of the vehicle 100 (e.g., vehicle speed V, distance DF, or time to reach the preceding vehicle, described later) within a set control range (e.g., set speed range R_V, set distance range R_DF, or time to reach the preceding vehicle, described later).

[0037] In this example, mechanically connecting the power unit 20 to the drive wheels to apply power to the drive wheels means inputting the power output from the internal combustion engine 21 to the drive wheels of the vehicle 100, and the vehicle 100 moves as power is input to the drive wheels in this way. Also, in this example, electrically connecting the power unit 20 to apply power to the drive wheels means inputting the power output from the electric motor 22 to the drive wheels of the vehicle 100, and the vehicle 100 moves as power is input to the drive wheels in this way.

[0038] Furthermore, the vehicle driving support device 10 is configured to perform autonomous driving control in a second driving mode (for example, normal vehicle speed control or normal inter-vehicle distance control, as described later) in which it maintains the control values ​​of its own vehicle 100 (for example, the vehicle speed V, the distance DF, or the time to reach the preceding vehicle TF, as described later) at set control values ​​(for example, set vehicle speed V_S, set distance DF_S, or set time to reach the preceding vehicle TF_S, as described later).

[0039] Furthermore, the vehicle driving support device 10 is configured to select either a first drive mode (for example, a hybrid drive mode described later) in which power other than the power generated by the power storage device can be used as the power to drive the vehicle 100, or a second drive mode (for example, a motor drive mode described later) in which only the power generated by the power storage device is used, and to selectively perform autonomous driving control in the first drive mode and autonomous driving control in the second drive mode.

[0040] In other words, the vehicle driving support device 10 is configured to selectively perform speed increase / decrease control (for example, eco speed control described later) which causes the vehicle 100 to drive autonomously while increasing or decreasing the vehicle speed of the vehicle 100 within a set speed range, and distance increase / decrease control (for example, eco distance control described later) which causes the vehicle 100 to drive autonomously while increasing or decreasing the distance between the vehicle 100 and other vehicles in the vicinity of the vehicle 100 (for example, a preceding vehicle 200) within a set distance range, or while increasing or decreasing the time required for the vehicle 100 to travel the above distance within a set time range.

[0041] Furthermore, the vehicle driving support device 10 is configured to selectively perform speed maintenance control (for example, normal speed control described later) which allows the vehicle 100 to drive autonomously while maintaining the vehicle speed of the vehicle 100 at a set speed, and distance maintenance control (for example, normal distance control described later) which allows the vehicle 100 to drive autonomously while maintaining the distance between the vehicle 100 and other vehicles in the vicinity of the vehicle 100 (for example, a preceding vehicle 200) at a set distance, or while maintaining the time required for the vehicle 100 to travel the above distance at a set time.

[0042] Furthermore, the vehicle driving support device 10 is configured to perform vehicle speed increase / decrease control and inter-vehicle distance increase / decrease control (for example, eco-vehicle speed control and eco-inter-vehicle distance control, for example, the latter described later) in a first drive mode (for example, the hybrid drive mode described later) in which both the internal combustion engine 21 and the electric motor 22 or only the internal combustion engine 21 are operated to power the vehicle 100 and drive it, and in a second drive mode (for example, the motor drive mode described later) in which only the electric motor 22 is operated to power the vehicle 100 and drive it.

[0043] Furthermore, the vehicle driving support device 10 is configured to selectively perform vehicle speed increase / decrease control and inter-vehicle distance increase / decrease control (for example, eco-vehicle speed control and eco-inter-vehicle distance control, for

[0044] In this example, the vehicle driving support device 10 can achieve a first state in which power generation losses in the power unit 20 are reduced by reducing the amount of energy consumed to generate power in the internal combustion engine 21 (engine energy consumption) by stopping the operation of the internal combustion engine 21, or by reducing the amount of energy consumed to generate power by the electric motor 22 (motor energy consumption) by stopping the power supply from the energy storage device 41 to the electric motor 22.

[0045] Furthermore, in this example, the vehicle driving support device 10 can achieve a first state in which power transmission loss from the power unit 20 to the drive wheels is reduced by disconnecting the power transmission path from the power unit 20 to the drive wheels of the vehicle 100, for example by disengaging the so-called clutch.

[0046] Furthermore, in this example, the vehicle driving support device 10 establishes a transmission path from the power unit 20 to the drive wheels of the vehicle 100, and applies power from the internal combustion engine 21 to the drive wheels of the vehicle 100 via this transmission path, thereby realizing a second state in which the power unit 20 is mechanically connected to the drive wheels of the vehicle 100 and power is applied to those drive wheels. More specifically, the vehicle driving support device 10 realizes a second state in which the power unit 20 is mechanically connected to the drive wheels of the vehicle 100 and power is applied to those drive wheels by performing the optimal traction control described later.

[0047] Furthermore, in this example, the vehicle driving support device 10 establishes a transmission path from the power unit 20 to the drive wheels of the vehicle 100, and applies power from the electric motor 22 to the drive wheels of the vehicle 100 via the transmission path, thereby realizing a second state in which the power unit 20 is electrically connected to the drive wheels and power is applied to the drive wheels.

[0048] Next, we will explain in more detail the control performed by the vehicle driving support system 10, using the example of a case where the other vehicle in the vicinity of the vehicle 100 is the preceding vehicle 200.

[0049] The vehicle driving support system 10 performs autonomous driving control as automatic driving control or autonomous driving control. Autonomous driving control is a control that drives the vehicle 100 by autonomously controlling the operation of the power unit 20 and the braking unit 30 to accelerate and decelerate the vehicle 100, and in this example, it includes inter-vehicle distance control and vehicle speed control.

[0050] Inter-vehicle distance control, as shown in Figure 2(A), is a control that is executed when a preceding vehicle 200 is present in front of the vehicle 100, and is a control that autonomously accelerates and decelerates the vehicle 100 based on a set preceding vehicle distance DF_S. The set preceding vehicle distance DF_S is the preceding vehicle distance DF set by the driver as the control target for inter-vehicle distance control.

[0051] Alternatively, the following distance control may be a control that is executed when a preceding vehicle 200 is present in front of the vehicle 100, and may autonomously accelerate or decelerate the vehicle 100 based on a set preceding vehicle arrival time TF_S. The set preceding vehicle arrival time TF_S is the preceding vehicle arrival time TF set by the driver as the control target for the following distance control. The preceding vehicle arrival time TF is a value obtained by dividing the preceding vehicle distance DF by the vehicle speed V (TF = DF / V). Therefore, the preceding vehicle arrival time TF is the time required for the vehicle 100 to travel the preceding vehicle distance DF.

[0052] More specifically, the adaptive cruise control includes both standard adaptive cruise control and eco-friendly adaptive cruise control.

[0053] Normal following distance control is a type of normal autonomous driving control that allows the vehicle 100 to drive autonomously while maintaining the distance DF to the preceding vehicle at a set preceding vehicle distance DF_S. Alternatively, normal following distance control may be a control that allows the vehicle 100 to drive autonomously while maintaining the time TF to the preceding vehicle to arrive at a set preceding vehicle to arrive at a set preceding vehicle time TF_S. Therefore, normal following distance control is what is known as follow driving control or adaptive cruise control.

[0054] Furthermore, the vehicle driving support device 10 may be configured to perform normal vehicle speed control (constant speed control), as described later, if the vehicle speed V increases during normal inter-vehicle distance control and reaches the set vehicle speed V_S.

[0055] Eco-distance control is a type of eco-autonomous driving control that allows the vehicle 100 to autonomously drive while increasing or decreasing the distance DF of the preceding vehicle within the set preceding vehicle distance range R_DF. This is achieved by starting coasting control when the distance DF of the preceding vehicle decreases and reaches the lower limit (lower limit preceding vehicle distance DF_L) of a predetermined range (set preceding vehicle distance range R_DF), and starting power control (optimal power control) when the distance DF of the preceding vehicle increases and reaches the upper limit (upper limit preceding vehicle distance DF_U) of the set preceding vehicle distance range R_DF. In other words, eco-distance control is a control that alternates between powering and coasting the vehicle 100 while allowing the distance DF of the preceding vehicle to fluctuate within a predetermined range (set preceding vehicle distance range R_DF).

[0056] Alternatively, eco-friendly inter-vehicle distance control is a control method that allows the vehicle 100 to autonomously travel while increasing or decreasing the time TF to reach the preceding vehicle within the set preceding vehicle time range R_TF. This is achieved by starting coasting control when the time TF to reach the preceding vehicle decreases and reaches the lower limit (lower limit preceding vehicle time TF_L) of a predetermined range (set preceding vehicle time range R_TF), and starting power control (optimal power control) when the time TF to reach the preceding vehicle increases and reaches the upper limit (upper limit preceding vehicle time TF_U) of the set preceding vehicle time range R_TF. In other words, eco-friendly inter-vehicle distance control is a control method that alternates between powering and coasting the vehicle 100 while allowing the time TF to reach the preceding vehicle to fluctuate within a predetermined range (set preceding vehicle time range R_TF).

[0057] In this example, the set preceding vehicle distance range R_DF is set to include the set preceding vehicle distance DF_S. More specifically, the set preceding vehicle distance range R_DF is set by defining the upper limit preceding vehicle distance DF_U as a distance greater than the set preceding vehicle distance DF_S by a predetermined value (control inter-vehicle distance width dD) (DF_U = DF_S + dD), and defining the lower limit preceding vehicle distance DF_L as a distance less than the set preceding vehicle distance DF_S by a predetermined value (control inter-vehicle distance width dD) (DF_L = DF_S - dD).

[0058] Furthermore, in this example, the set preceding vehicle time range R_TF is set to include the set preceding vehicle arrival time TF_S. More specifically, the set preceding vehicle time range R_TF is set by defining the upper limit preceding vehicle time TF_U as a time that is greater than the set preceding vehicle arrival time TF_S by a predetermined value (control preceding vehicle arrival time width dT) (TF_U = TF_S + dT), and the lower limit preceding vehicle time TF_L as a time that is less than the set preceding vehicle arrival time TF_S by a predetermined value (control preceding vehicle arrival time width dT) (TF_L = TF_S - dT).

[0059] Furthermore, optimal power control is a control that controls the operation of the power unit 20 so that power is output from the power unit 20 with maximum or near-maximum energy efficiency, in particular, a control that operates the internal combustion engine 21 at the optimal operating point (or an operating point near the optimal operating point). Furthermore, coasting control is a control that controls the operation of the power unit 20 so that the vehicle 100 travels by coasting.

[0060] On the other hand, vehicle speed control, as shown in Figure 2(B), is a control that is executed when there is no preceding vehicle 200 in front of the vehicle 100, and is a control that autonomously controls the driving speed (vehicle speed V) of the vehicle 100 based on a set vehicle speed V_S. The set vehicle speed V_S is the driving speed (vehicle speed V) of the vehicle 100 that is set by the driver as the control target by vehicle speed control.

[0061] As shown in Figure 1, the vehicle 100 is equipped with a vehicle speed detection device 61, such as a wheel speed sensor. The vehicle speed detection device 61 is electrically connected to the ECU 90. The vehicle driving assistance system 10 acquires the vehicle speed V using the vehicle speed detection device 61.

[0062] More specifically, vehicle speed control includes normal vehicle speed control and eco vehicle speed control.

[0063] Normal speed control is a type of normal autonomous driving control that allows the vehicle 100 to drive autonomously while maintaining its own speed V at a set speed V_S. Therefore, normal speed control is what is known as constant speed control or cruise control.

[0064] Eco-speed control is a control system that allows the vehicle 100 to autonomously travel while increasing or decreasing its own speed V within the set speed range R_V. This is achieved by starting coasting control when the vehicle speed V increases and reaches the upper limit (upper speed V_U) of a predetermined range (set speed range R_V), and starting optimal power control when the vehicle speed V decreases and reaches the lower limit (lower speed V_L) of the set speed range R_V. In other words, eco-speed control is a control system that alternates between powering and coasting the vehicle 100 while allowing the vehicle speed V to fluctuate within a predetermined range (set speed range R_V).

[0065] In this example, the set vehicle speed range R_V is set to include the set vehicle speed V_S. More specifically, the set vehicle speed range R_V is set by defining the upper limit vehicle speed V_U as a vehicle speed that is greater than the set vehicle speed V_S by a predetermined value (control vehicle speed width dV) (V_U = V_S + dV), and the lower limit vehicle speed V_L as a vehicle speed that is less than the set vehicle speed V_S by a predetermined value (control vehicle speed width dV) (V_L = V_S - dV).

[0066] <Specific operation of vehicle driver assistance systems> Next, the specific operation of the vehicle driving support system 10 will be described. The vehicle driving support system 10 performs autonomous driving control by executing the routine shown in Figure 4 at a predetermined calculation cycle.

[0067] When a predetermined timing occurs, the vehicle driving support device 10 starts processing from step S400 of the routine shown in Figure 4, proceeds to step S405, and determines whether the normal autonomous driving condition C1 is met.

[0068] The normal autonomous driving condition C1 is that autonomous driving is possible condition C2 is met, autonomous driving control is required, and eco autonomous driving control (economy driving control) is not required. Eco autonomous driving control includes eco vehicle speed control and eco inter-vehicle distance control. Furthermore, eco autonomous driving control is a control that causes the vehicle 100 to drive in a pulse-and-glide manner.

[0069] Furthermore, autonomous driving capability condition C2 is a condition in which the systems necessary for executing autonomous driving control are functioning normally, such as the surrounding information detection device 50 functioning normally, or a condition in which the gradient of the road on which the vehicle 100 is traveling is not relatively steep and the situation is not such that it is judged that the execution of eco autonomous driving control is undesirable. Note that the normal autonomous driving condition C1 does not necessarily have to include the condition that autonomous driving capability condition C2 is met.

[0070] Furthermore, as shown in Figure 1, the vehicle 100 is equipped with an autonomous driving request control 71, such as a driving support button, and an eco-autonomous driving request control 72, such as an economy driving button. The autonomous driving request control 71 and the eco-autonomous driving request control 72 are electrically connected to the ECU 90. The driver can request the vehicle driving support system 10 to execute autonomous driving control by operating the autonomous driving request control 71. The driver can also request the vehicle driving support system 10 to execute eco-autonomous driving control by operating the eco-autonomous driving request control 72.

[0071] If the vehicle driving assistance system 10 determines "Yes" in step S405, it proceeds to step S410 to determine whether or not a preceding vehicle 200 exists.

[0072] If the vehicle driving support system 10 determines "Yes" in step S410, it proceeds to step S415 and performs normal inter-vehicle distance control as autonomous driving control. Next, the vehicle driving support system 10 proceeds to step S420 and sets the value of the eco autonomous driving flag X_ECO to "0", and then proceeds to step S495 and terminates the processing of this routine.

[0073] On the other hand, if the vehicle driving support system 10 determines "No" in step S410, it proceeds to step S425 and performs normal vehicle speed control as autonomous driving control. Next, the vehicle driving support system 10 proceeds to step S430, sets the value of the eco autonomous driving flag X_ECO to "0", and then proceeds to step S495 to terminate the processing of this routine.

[0074] Furthermore, if the vehicle driving support device 10 determines "No" in step S405, it proceeds to step S435 to determine whether or not the eco-autonomous driving condition C3 is met.

[0075] Eco-autonomous driving condition C3 is the condition that autonomous driving capability condition C2 is met, that autonomous driving control is required, and that eco-autonomous driving control is required. Note that eco-autonomous driving condition C3 does not necessarily have to include the condition that autonomous driving capability condition C2 is met.

[0076] If the vehicle driving support device 10 determines "Yes" in step S435, it proceeds to step S440 to determine whether the traction condition C4, described later, is met.

[0077] If the vehicle driving assistance system 10 determines "Yes" in step S440, it proceeds to step S445 and executes the routine shown in Figure 7. This routine will be described later.

[0078] On the other hand, if the vehicle driving support device 10 determines "No" in step S440, it proceeds to step S450 and executes the routine shown in Figure 5 or Figure 6.

[0079] Therefore, if the vehicle driving support device 10 is configured to execute the routine shown in Figure 5 when it proceeds to step S450, it starts processing from step S500 of the routine shown in Figure 5, proceeds to step S505, and determines whether or not a preceding vehicle 200 exists.

[0080] If the vehicle driving support system 10 determines "Yes" in step S505, it proceeds to step S510 and executes eco-friendly distance control as autonomous driving control. Next, the vehicle driving support system 10 proceeds to step S515, sets the value of the eco-autonomous driving flag X_ECO to "1", and then proceeds to step S595 to terminate the processing of this routine.

[0081] On the other hand, if the vehicle driving support device 10 determines "No" in step S505, it proceeds to step S520 and executes eco-speed control as autonomous driving control. Next, the vehicle driving support device 10 proceeds to step S525, sets the value of the eco-autonomous driving flag X_ECO to "1", and then proceeds to step S595 to terminate the processing of this routine.

[0082] Alternatively, if the vehicle driving support device 10 is configured to execute the routine shown in Figure 6 when the process proceeds to step S450, it starts processing from step S600 of the routine shown in Figure 6, proceeds to step S605, and determines whether or not a preceding vehicle 200 exists.

[0083] If the vehicle driving support system 10 determines "Yes" in step S605, it proceeds to step S607 to determine whether the distance DR of the following vehicle is greater than a predetermined distance (proximity determination distance DR_N).

[0084] Furthermore, the vehicle driving support device 10 may be configured to determine in step S607 whether the time TR for the following vehicle to arrive is longer than a predetermined time (proximity determination time TR_N). The time TR for the following vehicle to arrive is a value obtained by dividing the distance DR for the following vehicle by the speed of the following vehicle 300 (following vehicle speed VR) (TR = DR / VR). Therefore, the time TR for the following vehicle to arrive is the time required for the following vehicle 300 to travel the distance DR for the following vehicle.

[0085] If the vehicle driving support system 10 determines "Yes" in step S607, it proceeds to step S610 and executes eco-friendly distance control as autonomous driving control. Next, the vehicle driving support system 10 proceeds to step S615, sets the value of the eco-autonomous driving flag X_ECO to "1", and then proceeds to step S695 to terminate the processing of this routine.

[0086] On the other hand, if the vehicle driving support system 10 determines "No" in step S607, it proceeds to step S616, cancels eco-friendly distance control, and executes normal distance control. Next, the vehicle driving support system 10 proceeds to step S617, sets the value of the eco-autonomous driving flag X_ECO to "0", and then proceeds to step S695, terminating the processing of this routine.

[0087] As described above, the vehicle driving support device 10 is configured to perform normal inter-vehicle distance control (autonomous driving control in a second driving mode that maintains the control value at a set control value) which maintains the distance of the preceding vehicle DF at a set distance of the preceding vehicle DF_S. During the execution of eco inter-vehicle distance control (autonomous driving control in a first driving mode), if the following vehicle distance DR is less than or equal to the proximity determination distance DR_N or the following vehicle arrival time TR is less than or equal to the proximity determination time TR_N (driving mode switching conditions in which the following vehicle detection device that detects the following vehicle 300 is functioning correctly and the following vehicle 300 is detected and the distance between the following vehicle 300 and the own vehicle 100 is less than or equal to a predetermined distance or the time required for the own vehicle 100 to travel the distance between the following vehicle 300 and the own vehicle 100 is less than or equal to a predetermined time), the device is configured to switch the control to allow the own vehicle 100 to drive autonomously (the mode in which the own vehicle 100 drives autonomously) from eco inter-vehicle distance control to normal inter-vehicle distance control (switching from the first driving mode to the second driving mode).

[0088] When vehicle 100 is autonomously driving using eco-friendly distance control, if there is a following vehicle 300, and the distance DF to the preceding vehicle increases or decreases excessively, the following vehicle 300 will also increase or decrease its speed significantly, which may hinder the smooth flow of traffic for surrounding vehicles, including the following vehicle 300.

[0089] According to the vehicle driving support system 10, when a following vehicle 300 is relatively close to the vehicle 100, the control for autonomous driving of the vehicle 100 is switched from eco-friendly inter-vehicle distance control to normal inter-vehicle distance control. This ensures that the distance DF to the preceding vehicle remains constant. Therefore, even when a following vehicle 300 is relatively close to the vehicle 100, the vehicle 100 can be driven autonomously in a way that maintains smooth traffic flow for surrounding vehicles.

[0090] Furthermore, the vehicle driving support device 10 is configured to perform normal inter-vehicle distance control (inter-vehicle distance maintenance control) which allows the vehicle 100 to drive autonomously while maintaining the distance from the preceding vehicle DF (inter-vehicle distance) at a set distance from the preceding vehicle DF_S (set distance) or while maintaining the time to reach the preceding vehicle TF (the time required for the vehicle 100 to travel the inter-vehicle distance between the vehicle 100 and surrounding vehicles) at a set time to reach the preceding vehicle TF_S (set time). Furthermore, the vehicle driving support device 10 is configured to stop the eco-distance control (distance increase / decrease control) and execute normal distance control (distance maintenance control) if, during the execution of eco-distance control (distance increase / decrease control), the following vehicle distance DR is less than or equal to the proximity determination distance DR_N or the following vehicle arrival time TR is less than or equal to the proximity determination time TR_N (driving mode switching conditions in which the following vehicle detection device that detects the following vehicle 300 is functioning correctly, the following vehicle 300 is detected and the distance between the following vehicle 300 and the own vehicle 100 is less than or equal to a predetermined distance or the time required for the own vehicle 100 to travel the distance between the following vehicle 300 and the own vehicle 100 is less than or equal to a predetermined time).

[0091] When vehicle 100 is autonomously driving using eco-friendly distance control, if there is a following vehicle 300, and the distance DF to the preceding vehicle increases or decreases excessively, the following vehicle 300 will also increase or decrease its speed significantly, which may hinder the smooth flow of traffic for surrounding vehicles, including the following vehicle 300.

[0092] According to the vehicle driving support system 10, if a following vehicle 300 is relatively close to the vehicle 100, eco-friendly inter-vehicle distance control is discontinued and normal inter-vehicle distance control is performed. This ensures that the distance DF to the preceding vehicle remains constant. Therefore, even when a following vehicle 300 is relatively close to the vehicle 100, the vehicle 100 can be driven autonomously in a way that maintains smooth traffic flow for surrounding vehicles.

[0093] On the other hand, if the vehicle driving support system 10 determines "No" in step S605, it proceeds to step S618 to determine whether the following vehicle distance DR is greater than the proximity determination distance DR_N.

[0094] Furthermore, the vehicle driving support device 10 may be configured to determine in step S618 whether the time TR for the arrival of the following vehicle is longer than the proximity determination time TR_N.

[0095] If the vehicle driving support system 10 determines "Yes" in step S618, it proceeds to step S620 and executes eco-speed control as autonomous driving control. Next, the vehicle driving support system 10 proceeds to step S625 and sets the value of the eco-autonomous driving flag X_ECO to "1", and then proceeds to step S695 to terminate the processing of this routine.

[0096] On the other hand, if the vehicle driving support device 10 determines "No" in step S618, it proceeds to step S626, cancels eco-speed control, and executes normal speed control. Next, the vehicle driving support device 10 proceeds to step S627, sets the value of the eco-autonomous driving flag X_ECO to "0", and then proceeds to step S695, terminating the processing of this routine.

[0097] As described above, the vehicle driving support device 10 is configured to perform normal speed control (autonomous driving control of the vehicle 100 in a second driving mode that maintains the vehicle speed V at a set speed V_S), and when the following conditions are met during the execution of eco speed control (autonomous driving control in the first driving mode), such as the following vehicle distance DR being less than or equal to the proximity determination distance DR_N or the following vehicle arrival time TR being less than or equal to the proximity determination time TR_N (driving mode switching conditions where the following vehicle detection device that detects the following vehicle 300 is functioning correctly, the following vehicle 300 is detected, and the distance between the following vehicle 300 and the vehicle 100 is less than or equal to a predetermined distance, or the time required for the vehicle 100 to travel the distance between the following vehicle 300 and the vehicle 100 is less than or equal to a predetermined time), the device is configured to switch the control to make the vehicle 100 drive autonomously (the mode in which the vehicle 100 drives autonomously) from eco speed control to normal speed control (switching from the first driving mode to the second driving mode).

[0098] When vehicle 100 is autonomously driving using eco-speed control, if there is a following vehicle 300, and the vehicle speed V increases or decreases excessively, the following vehicle 300 will also increase or decrease its speed significantly, which may hinder the smooth flow of traffic for surrounding vehicles, including the following vehicle 300.

[0099] According to the vehicle driving support system 10, when a following vehicle 300 is relatively close to the vehicle 100, the control for autonomous driving of the vehicle 100 is switched from eco-speed control to normal speed control. This ensures that the vehicle speed V is kept constant. Therefore, even when a following vehicle 300 is relatively close to the vehicle 100, the vehicle 100 can be driven autonomously in a way that maintains smooth traffic flow for surrounding vehicles.

[0100] Furthermore, the vehicle driving support device 10 is configured to perform normal speed control (speed maintenance control) which allows the vehicle 100 to drive autonomously while maintaining its own vehicle speed V at a set vehicle speed V_S. The vehicle driving support device 10 is configured to stop eco speed control (speed increase / decrease control) and perform normal speed control (speed maintenance control) when the following vehicle distance DR is less than or equal to the proximity determination distance DR_N or the following vehicle arrival time TR is less than or equal to the proximity determination time TR_N (driving mode switching conditions which include the following vehicle detection device that detects the following vehicle 300 being normal and the following vehicle 300 being detected and the distance between the following vehicle 300 and the vehicle 100 being less than or equal to a predetermined distance or the time required for the vehicle 100 to travel the distance between the following vehicle 300 and the vehicle 100 being less than or equal to a predetermined time).

[0101] When vehicle 100 is autonomously driving using eco-speed control, if there is a following vehicle 300, and the vehicle speed V increases or decreases excessively, the following vehicle 300 will also increase or decrease its speed significantly, which may hinder the smooth flow of traffic for surrounding vehicles, including the following vehicle 300.

[0102] According to the vehicle driving support system 10, when a following vehicle 300 is relatively close to the vehicle 100, eco-speed control is discontinued and normal speed control is performed. This ensures that the vehicle speed V is maintained at a constant level. Therefore, even when a following vehicle 300 is relatively close to the vehicle 100, the vehicle 100 can be driven autonomously in a way that maintains smooth traffic flow for surrounding vehicles.

[0103] Furthermore, if the vehicle driving assistance device 10 determines "No" in step S435 of the routine shown in Figure 4, it proceeds to step S455 to perform normal vehicle speed control, and then proceeds to step S495 to terminate the processing of this routine.

[0104] Next, we will explain the routine shown in Figure 7.

[0105] The powering condition C4 determined in step S440 of the routine shown in Figure 4 is that the value of the eco-autonomous driving flag X_ECO is "1" and optimal powering control is being executed. In other words, powering condition C4 is that when eco-autonomous driving control is being executed, deceleration of the vehicle 100 is not required.

[0106] The vehicle driving support system 10 determines "Yes" at step S440 of the routine shown in Figure 4, and proceeds to step S445. Then, it starts processing from step S700 of the routine shown in Figure 7, proceeds to step S705, and determines whether the value of the hybrid drive mode flag X_HV is "1".

[0107] The value of the hybrid drive mode flag X_HV is currently set to "1" when the vehicle 100 is running in hybrid drive mode, and to "0" when the vehicle 100 is not running in hybrid drive mode. The hybrid drive mode is a mode in which the vehicle 100 is driven by operating both the internal combustion engine 21 and the electric motor 22, or by operating only the internal combustion engine 21, according to the requested power P_REQ. The requested power P_REQ is the power requested to be output from the power unit 20.

[0108] If the vehicle driving support device 10 determines "Yes" in step S705, it proceeds to step S710, sets the low efficiency index threshold IX_T to the first low efficiency index threshold IX1, and sets the coasting acceleration threshold G_T to the first coasting acceleration threshold G1, and then proceeds to step S725. The low efficiency index threshold IX_T is the threshold used in the determination in step S725, and the coasting acceleration threshold G_T is the threshold used in the determination in step S735, which will be described later.

[0109] On the other hand, if the vehicle driving support device 10 determines "No" in step S705, it proceeds to step S715 to determine whether the value of the motor drive mode flag X_EV is "1".

[0110] The motor drive mode flag X_EV is currently set to "1" when the vehicle 100 is running in motor drive mode, and to "0" when the vehicle 100 is not running in motor drive mode. Motor drive mode is a mode in which the vehicle 100 is driven by operating only the electric motor 22.

[0111] If the vehicle driving support system 10 determines "Yes" in step S715, it proceeds to step S720, sets the low efficiency index threshold IX_T to the second low efficiency index threshold IX2, and sets the coasting acceleration threshold G_T to the second coasting acceleration threshold G2, and then proceeds to step S725. The second low efficiency index threshold IX2 is set to a value greater than the first low efficiency index threshold IX1, and the second coasting acceleration threshold G2 is set to a value greater than the first coasting acceleration threshold G1.

[0112] When the vehicle driving support system 10 proceeds to step S725, it determines whether or not the low efficiency condition C5 is met.

[0113] Low efficiency condition C5 is a condition in which, when eco-autonomous driving control (eco-inter-vehicle distance control or eco-vehicle speed control) is performed to drive the vehicle 100 while switching the control that controls the driving of the vehicle 100 (vehicle driving control) between coasting control and optimal power control, the driving energy efficiency (energy efficiency of the power unit 20 related to the driving of the vehicle 100) is lower than the driving energy efficiency when the vehicle 100 is driven by normal vehicle speed control, when considering the gradient of the road on which the vehicle 100 is traveling (road gradient θ).

[0114] In this example, the low-efficiency condition C5 is the condition that the low-efficiency index IX is greater than the low-efficiency index threshold IX_T, as shown in Equation 1 below.

[0115] IX > IXth …(1)

[0116] The low efficiency index IX is an index that indicates the degree to which the driving energy efficiency (driving energy efficiency) of the vehicle decreases when eco-autonomous driving control is in operation, compared to the energy efficiency (driving energy efficiency) of the vehicle when normal vehicle speed control is in operation.

[0117] In this example, the low efficiency index IX is obtained by calculation according to Equation 2 below.

[0118] IX = |Gd| - k × |Ga| …(2) Gd = -F / M + g × sinθ …(3) Ga=(P_OPT-F) / M+g×sinθ …(4)

[0119] In Equation 2, "Gd" is the acceleration of the vehicle 100 (coasting acceleration) achieved when coasting control is performed, and is obtained by calculation according to Equation 3 above. The coasting acceleration Gd is obtained as a negative value when the vehicle speed V is decreasing, and as a positive value when the vehicle speed V is increasing.

[0120] Furthermore, in Equation 2, "Ga" is the acceleration of the vehicle 100 achieved when optimal power control is performed (optimal power acceleration), and is obtained by calculation according to Equation 4 above. The optimal power acceleration Ga is also obtained as a negative value when the vehicle speed V is decreasing, and as a positive value when the vehicle speed V is increasing.

[0121] Furthermore, in equations 3 and 4, "F" is the running resistance of the vehicle 100, which is obtained, for example, by calculation according to equation 5 below. Also, "M" is the weight of the vehicle 100, "g" is the acceleration due to gravity, and "θ" is the road surface gradient. Furthermore, "P_OPT" is the power (optimal power action) applied to the vehicle 100 from the power unit 20 when optimal power control is being performed.

[0122] F = a × V 2 +b × V + c …(5)

[0123] In Equation 5, "V" is the driving speed (vehicle speed) of the vehicle 100, and "a", "b", and "c" are coefficients determined to enable accurate acquisition of the driving resistance of the vehicle 100 based on the vehicle speed V.

[0124] Furthermore, the low efficiency index thresholds IX_T (first low efficiency index threshold IX1 and second low efficiency index threshold IX2) are predetermined values, and in Equation 1, "k" is a coefficient, which is set to a predetermined value. These low efficiency index thresholds IX_T and coefficient k are set as follows.

[0125] In other words, when the vehicle 100 is traveling on a flat road, if the vehicle 100 is driven using eco-autonomous driving control (eco-inter-vehicle distance control or eco-vehicle speed control), which controls the vehicle's movement by switching between coasting control and optimal power control, coasting control is executed when deceleration of the vehicle 100 is required. This results in higher driving energy efficiency compared to when the vehicle 100 is driven using normal vehicle speed control.

[0126] However, when the vehicle 100 is traveling uphill and is driven using eco-autonomous driving control, the switching between coasting control and optimal power control occurs frequently within a certain period of time. This may result in a decrease in driving energy efficiency compared to when the vehicle 100 is driven using normal vehicle speed control. In particular, when the vehicle 100 is autonomously driving in hybrid drive mode, the internal combustion engine 21 is started and stopped frequently, which makes it highly likely that driving energy efficiency will decrease.

[0127] Therefore, in this example, assuming that the low efficiency index IX is obtained by calculation according to equations 2 to 4, the combination of the low efficiency index threshold IX_T and coefficient k that makes the driving energy efficiency when the vehicle 100 is driven by eco-autonomous driving control equal to the driving energy efficiency when the vehicle 100 is driven by normal vehicle speed control is determined in advance by experimentation, etc., based on the relationship between the road gradient θ, coasting acceleration Gd, and optimal power acceleration Ga, and these low efficiency index threshold IX_T and coefficient k are used in equations 1 and 2, respectively. In this example, the coefficient k is set to a value greater than "0" and less than or equal to "1".

[0128] Therefore, if the low efficiency index IX is greater than the low efficiency index threshold IX_T, the driving energy efficiency will be higher when the vehicle 100 is driven using normal vehicle speed control than when the vehicle 100 is driven using eco-autonomous driving control.

[0129] From the above, it can be said that in step S725, the vehicle driving support system 10 determines whether it is more energy-efficient to continue executing eco-autonomous driving control or to terminate eco-autonomous driving control and execute normal vehicle speed control.

[0130] Furthermore, the low-efficiency condition C5 can also be described as an uphill gradient condition where, during the execution of eco-autonomous driving control, the road gradient θ is greater than a predetermined uphill gradient threshold θup. In this case, the predetermined uphill gradient threshold θup can be described as the gradient at which the absolute value of the deceleration of the vehicle 100 when it is driven by coasting control while the road gradient θ is uphill is greater than or equal to a predetermined value (predetermined deceleration threshold). Alternatively, the predetermined uphill gradient threshold θup can be described as the gradient at which the acceleration and deceleration of the vehicle 100 when it is driven by optimal power control while the road gradient θ is uphill is less than or equal to a predetermined value (predetermined acceleration threshold). Alternatively, the predetermined uphill gradient threshold θup can be described as the gradient at which the ratio of the absolute value of the coasting acceleration Gd to the optimal power acceleration Ga is greater than a predetermined ratio while the road gradient θ is uphill.

[0131] Furthermore, to prevent frequent switching between eco-autonomous driving control and normal vehicle speed control, hysteresis may be provided in the low efficiency index threshold IX_T.

[0132] Furthermore, if the low-efficiency condition C5 is met and the vehicle driving control is switched from eco-autonomous driving control to normal vehicle speed control, and then it is determined that a preceding vehicle 200 exists while the normal vehicle speed control is being executed, the vehicle driving control will be switched from normal vehicle speed control to normal inter-vehicle distance control.

[0133] Furthermore, after the low-efficiency condition C5 is met and the vehicle driving control switches from eco-autonomous driving control to normal speed control, when the low-efficiency condition C5 is no longer met, the vehicle driving control switches from normal speed control to eco-autonomous driving control. In other words, in this example, when the low-efficiency condition C5 is met, the eco-autonomous driving control is temporarily terminated, and then when the low-efficiency condition C5 is no longer met, the eco-autonomous driving control is resumed. However, it is also possible that the eco-autonomous driving control is terminated when the low-efficiency condition C5 is met, and then does not resume even when the low-efficiency condition C5 is no longer met.

[0134] Furthermore, as shown in Figure 1, the vehicle 100 is equipped with a road gradient acquisition device 62. The road gradient acquisition device 62 is a device that acquires the gradient of the road on which the vehicle 100 is traveling, and is, for example, a gyro sensor. The road gradient acquisition device 62 is electrically connected to the ECU 90. The vehicle driving support system 10 acquires the gradient of the road on which the vehicle 100 is traveling as a road gradient θ using the road gradient acquisition device 62.

[0135] If the vehicle driving assistance device 10 determines "Yes" in step S725, it proceeds to step S730 to perform normal vehicle speed control, and then proceeds to step S795 to terminate the processing of this routine.

[0136] Thus, the vehicle driving support system 10 is configured to perform normal speed control (autonomous driving control in constant speed mode) that maintains the vehicle speed V at a set vehicle speed V_S. Furthermore, the vehicle driving support system 10 is configured to discontinue eco autonomous driving control (autonomous driving control in first driving mode) and perform normal speed control (autonomous driving control in constant speed mode) when the low efficiency condition C5 (second condition) is met. The low efficiency condition C5 (second condition) is a condition that is likely to be met when the vehicle 100 is traveling on an uphill road or when the vehicle 100 is traveling at a relatively high speed (when the vehicle 100 is traveling at a speed of a predetermined speed or higher). Furthermore, the low efficiency index threshold IX_T is set to the first low efficiency index threshold IX1 when the vehicle 100 is running in hybrid drive mode (first drive mode), and to the second low efficiency index threshold IX2 when it is running in motor drive mode (second drive mode), with the first low efficiency index threshold IX1 being smaller than the second low efficiency index threshold IX2. Therefore, the low efficiency condition C5 (second condition) is set to be more likely to be met when the vehicle 100 is autonomously driven by eco-autonomous driving control in hybrid drive mode (first drive mode) than when the vehicle 100 is autonomously driven by eco-autonomous driving control in motor drive mode (second drive mode).

[0137] When the vehicle 100 is traveling uphill or at high speed, if the vehicle 100 is allowed to travel autonomously using coasting control, the vehicle speed V may decrease significantly. Furthermore, even if the vehicle 100 is allowed to travel autonomously using optimal power control, it may not be possible to adequately increase the vehicle speed V. Therefore, when the vehicle 100 is traveling uphill or at high speed, if the vehicle 100 is allowed to travel autonomously using eco-autonomous driving control, the effect of reducing energy consumption will decrease.

[0138] Furthermore, when the vehicle 100 is autonomously driven using eco-autonomous driving control in hybrid drive mode, the set vehicle speed range R_V or the set preceding vehicle distance range R_DF is set to a larger range than when the vehicle 100 is autonomously driven using eco-autonomous driving control in motor drive mode. Therefore, when the vehicle 100 is driving uphill or at high speed, the effect of reducing energy consumption is reduced when the vehicle 100 is autonomously driven using eco-autonomous driving control in hybrid drive mode.

[0139] According to the vehicle driving support system 10, the low-efficiency condition C5 is a condition that is likely to occur when the vehicle 100 is traveling uphill or at high speed, and is set to occur more likely when the vehicle 100 is autonomously driven by eco-autonomous driving control in hybrid drive mode than when the vehicle 100 is autonomously driven by eco-autonomous driving control in motor drive mode. When the low-efficiency condition C5 is met, the eco-autonomous driving control is canceled and normal vehicle speed control is executed. In other words, when the vehicle 100 is traveling uphill or at high speed and the vehicle 100 is autonomously driven by eco-autonomous driving control in hybrid drive mode, the eco-autonomous driving control is likely to be canceled and normal vehicle speed control will be executed. Therefore, a certain reduction in energy consumption can be ensured.

[0140] Furthermore, according to the vehicle driving support system 10, the vehicle speed V is controlled as shown in Figure 8. In the example shown in Figure 8, until time t50, the vehicle 100 is traveling on a road with a road gradient θ of zero, i.e., a flat road, and optimal power control is being performed. Therefore, until time t50, the vehicle speed V is gradually increasing. The optimal power acceleration Ga and coasting acceleration Gd at this time are the first optimal power acceleration Ga1 and the first coasting acceleration Gd1, respectively. The first optimal power acceleration Ga1 is a positive value, and the first coasting acceleration Gd1 is a negative value.

[0141] Then, at time t50, when the vehicle speed V reaches the upper limit vehicle speed V_U, coasting control is initiated. At this time, the vehicle 100 is traveling on a road with a road gradient θ of zero, and therefore on a flat road. As a result, the vehicle speed V begins to decrease. The optimal acceleration Ga and coasting acceleration Gd at this time are also the first optimal acceleration Ga1 and first coasting acceleration Gd1, respectively.

[0142] Subsequently, at time t51, vehicle 100 begins to travel uphill. In the example shown in Figure 8, the road gradient θ continues to increase from time t51 to time t53, and then becomes a constant value θ1 from time t53 onward. Therefore, from time t51 to time t53, the optimal accelerating Ga and coasting acceleration Gd gradually decrease. In other words, the absolute value of the optimal accelerating Ga gradually decreases, and the absolute value of the coasting acceleration Gd gradually increases. Then, from time t53 onward, the optimal accelerating Ga and coasting acceleration Gd become constant at the second optimal accelerating Ga2 and second coasting acceleration Gd2, respectively.

[0143] Even after time t51, the vehicle speed V continues to decrease. In the example shown in Figure 8, at time t52, the low-efficiency condition C5 is met, eco-autonomous driving control ends, and normal vehicle speed control begins. At this time, since the vehicle speed V is smaller than the set vehicle speed V_S, the vehicle 100 is accelerated, the vehicle speed V increases, and after reaching the set vehicle speed V_S, the acceleration of the vehicle 100 is controlled so that the vehicle speed V is maintained at the set vehicle speed V_S.

[0144] According to this, if the low-efficiency condition C5 is met while eco-autonomous driving control is in operation, eco-autonomous driving control will terminate and normal vehicle speed control will be executed. Therefore, it is possible to prevent a decrease in driving energy efficiency caused by the continuous execution of eco-autonomous driving control.

[0145] On the other hand, if the vehicle driving support device 10 determines "No" in step S725, it proceeds to step S735 to determine whether or not the coasting acceleration condition C6 is met.

[0146] Coasting acceleration condition C6 is the condition that the vehicle 100 is traveling on a downhill road with a gentle gradient. In this example, coasting acceleration condition C6 is the condition that the coasting acceleration Gd is greater than zero, as shown in equation 6 below, and the absolute value of the coasting acceleration Gd is greater than or equal to the coasting acceleration threshold G_T, as shown in equation 7 below.

[0147] Gd>0 …(6) |Gd|≧G_T …(7)

[0148] The coasting acceleration threshold G_T is a threshold used to determine whether the vehicle 100 is traveling on a gently sloping downhill road, and in this example, it is set to a positive value close to "0". Therefore, the coasting acceleration condition C6 can also be said to be a downhill slope condition, which is that the road slope θ is greater than a predetermined value (predetermined downhill slope threshold θdown).

[0149] If the vehicle driving support system 10 determines "Yes" in step S735, it proceeds to step S740 to determine whether the driving speed condition C7 is met.

[0150] The driving speed condition C7 is the condition that the vehicle speed V is less than the set vehicle speed V_S, as shown in equation 8 below.

[0151] V <V_S …(8)

[0152] If the vehicle driving support device 10 determines "Yes" in step S740, it proceeds to step S745 to perform coasting control, and then proceeds to step S795 to terminate the processing of this routine.

[0153] Thus, when the coasting acceleration condition C6 (downhill gradient condition) is met, and the vehicle speed V is less than the set vehicle speed V_S (predetermined driving speed), the eco autonomous driving control is terminated and coasting control is executed.

[0154] In other words, when the vehicle 100 is traveling on a downhill road with a gentle gradient and its own vehicle speed V is less than the set vehicle speed V_S, the vehicle driving support device 10 performs coasting control because the vehicle speed V will increase even if the vehicle 100 is allowed to coast.

[0155] On the other hand, if the vehicle driving support device 10 determines "No" in step S740, it proceeds to step S750 to perform normal vehicle speed control, and then proceeds to step S795 to terminate the processing of this routine.

[0156] Thus, when the coasting acceleration condition C6 (downhill gradient condition) is met, and the vehicle speed V is equal to or greater than the set vehicle speed V_S (predetermined driving speed), the eco autonomous driving control is terminated and normal vehicle speed control is executed.

[0157] Furthermore, after "Yes" is determined in step S740 and coasting control is started in step S745, when the vehicle speed V reaches the set vehicle speed V_S, the vehicle driving control is switched from coasting control to normal vehicle speed control.

[0158] Thus, the vehicle driving support device 10 is configured to stop eco-autonomous driving control (autonomous driving control in the first driving mode) and execute coasting control (autonomous driving control by power control in the first state) when the coasting acceleration condition C6 (first condition) is met. The coasting acceleration condition C6 (first condition) is a condition that is likely to be met when the vehicle 100 is traveling downhill. Furthermore, the coasting acceleration threshold G_T is set to the first coasting acceleration threshold G1 when the vehicle 100 is traveling in hybrid drive mode (first drive mode), and to the second coasting acceleration threshold G2 when it is traveling in motor drive mode (second drive mode), with the first coasting acceleration threshold G1 being a smaller value than the second coasting acceleration threshold G2. Therefore, the coasting acceleration condition C6 (first condition) is set to be more likely to be met when the vehicle 100 is autonomously driven using eco-autonomous driving control in hybrid drive mode (autonomous driving control in first drive mode) than when the vehicle 100 is autonomously driven using eco-autonomous driving control in motor drive mode (autonomous driving control in second drive mode).

[0159] When vehicle 100 is traveling downhill, even if vehicle 100 is autonomously driven by coasting control, the vehicle speed V tends to increase. Therefore, there is no need to increase the vehicle speed V by autonomously driving vehicle 100 using optimal power control. Consequently, when vehicle 100 is traveling downhill, the effect of reducing energy consumption is greater when vehicle 100 is autonomously driven by coasting control than when vehicle 100 is autonomously driven by optimal power control. Furthermore, the effect of reducing energy consumption by not performing autonomous driving of vehicle 100 by optimal power control is greater when autonomous driving of vehicle 100 by eco-autonomous driving control is performed in hybrid drive mode than when autonomous driving of vehicle 100 by eco-autonomous driving control is performed in motor drive mode.

[0160] According to the vehicle driving support system 10, coasting acceleration condition C6 is a condition that is likely to be met when the vehicle 100 is traveling downhill. In other words, coasting acceleration condition C6 is a condition that makes it likely that eco-autonomous driving control will be canceled and coasting control will be executed when the vehicle 100 is traveling downhill. Moreover, coasting acceleration condition C6 is set to be less likely to be met when the vehicle 100 is autonomously driven by eco-autonomous driving control in motor drive mode than when the vehicle 100 is autonomously driven by eco-autonomous driving control in hybrid drive mode. In other words, coasting acceleration condition C6 is a condition that makes it less likely that eco-autonomous driving control will be canceled and coasting control will be executed when the vehicle 100 is autonomously driven by eco-autonomous driving control in motor drive mode. Therefore, a significant reduction in energy consumption can be obtained.

[0161] Furthermore, according to the vehicle driving support system 10, the vehicle speed V is controlled as shown in Figure 9. In the example shown in Figure 9, until time t60, the vehicle 100 is traveling on a road with a road gradient θ of zero, i.e., a flat road, and optimal power control is being performed. Therefore, until time t60, the vehicle speed V is gradually increasing. The optimal power acceleration Ga and coasting acceleration Gd at this time are the first optimal power acceleration Ga1 and the first coasting acceleration Gd1, respectively. The first optimal power acceleration Ga1 is a positive value, and the first coasting acceleration Gd1 is a negative value.

[0162] Subsequently, at time t60, vehicle 100 begins to travel downhill. In the example shown in Figure 9, the road gradient θ continues to decrease from time t60 to time t62, and becomes a constant value θ2 from time t62 onward. Therefore, from time t60 to time t62, the optimal accelerating Ga and coasting acceleration Gd gradually increase. In other words, the absolute value of the optimal accelerating Ga gradually increases. On the other hand, the coasting acceleration Gd is a negative value until time t61, so its absolute value gradually decreases, and from time t61 onward, it becomes a positive value, so its absolute value gradually increases. Then, from time t62 onward, the optimal accelerating Ga and coasting acceleration Gd become constant at the third optimal accelerating Ga3 and third coasting acceleration Gd3, respectively.

[0163] In the example shown in Figure 9, optimal power control continues from time t60 to time t61, and since the vehicle 100 is traveling downhill, the vehicle speed V continues to increase at a relatively large rate, and at time t61, the coasting acceleration condition C6 is met. At this time, since the vehicle speed V is smaller than the set vehicle speed V_S, eco autonomous driving control ends and coasting control begins. As a result, the rate of increase of the vehicle speed V decreases, but the vehicle speed V continues to increase.

[0164] Then, at time t62, when the vehicle speed V reaches the set vehicle speed V_S, coasting control ends and normal vehicle speed control begins. As a result, after the vehicle speed V reaches the set vehicle speed V_S, the acceleration and deceleration of the vehicle 100 are controlled to maintain the set vehicle speed V_S.

[0165] For example, when vehicle 100 is traveling downhill, if vehicle 100 is coasting, not only will vehicle 100 not decelerate, but it will also accelerate, causing its vehicle speed V to become excessively high. As a result, the eco-autonomous driving control will not maintain vehicle speed V within the set vehicle speed range R_V, or the distance DF to the preceding vehicle will not be maintained within the set preceding vehicle distance range R_DF. In such situations, it is undesirable to continue executing the eco-autonomous driving control.

[0166] According to the vehicle driving support system 10, when the coasting acceleration condition C6 is met, the eco-autonomous driving control is terminated. Therefore, it is possible to prevent the eco-autonomous driving control from continuing to be executed in situations where its execution is undesirable.

[0167] Furthermore, if the vehicle driving support device 10 determines "No" in step S735, it proceeds to step S505 of the routine shown in Figure 5 via step S755, executes the process as described above, and then terminates the processing of this routine.

[0168] Furthermore, if the vehicle driving support device 10 determines "No" in step S715, it proceeds to step S760 to execute engine continuous operation control, and then proceeds to step S795 to terminate the processing of this routine. Engine continuous operation control is a mode in which the vehicle 100 is driven in engine drive mode. Engine drive mode is a mode in which the internal combustion engine 21 is kept running.

[0169] Furthermore, the vehicle driving support system 10 is configured to execute the routine shown in Figure 10 at a predetermined calculation cycle. Therefore, at a predetermined timing, the vehicle driving support system 10 starts processing from step S1000 of the routine shown in Figure 10, proceeds to step S1005, and determines whether or not the engine continuous operation condition C8 is met.

[0170] Engine continuous operation condition C8 is a condition that is met when it is necessary to keep the internal combustion engine 21 running. For example, if the amount of charge in the energy storage device 41 falls below a predetermined amount (predetermined charge amount), and it is necessary to operate the internal combustion engine 21 to charge the energy storage device 41, then it becomes necessary to keep the internal combustion engine 21 running.

[0171] If the vehicle driving support device 10 determines "No" in step S1005, it proceeds to step S1010 to determine whether the requested power P_REQ is equal to or greater than the predetermined requested power P_REQ_T.

[0172] If the vehicle driving support system 10 determines "Yes" in step S1010, it proceeds to step S1015, sets the value of the hybrid drive mode flag X_HV to "1", and sets the value of the motor drive mode flag X_EV to "0", and then proceeds to step S1095, terminating the processing of this routine. In this case, the vehicle 100 is driven in hybrid drive mode.

[0173] On the other hand, if the vehicle driving support system 10 determines "No" in step S1010, it proceeds to step S1020, sets the value of the hybrid drive mode flag X_HV to "0", and sets the value of the motor drive mode flag X_EV to "1", and then proceeds to step S1095, terminating the processing of this routine. In this case, the vehicle 100 is driven in motor drive mode.

[0174] Furthermore, if the vehicle driving support device 10 determines "Yes" in step S1005, it proceeds to step S1025, sets the value of the hybrid drive mode flag X_HV to "0", sets the value of the motor drive mode flag X_EV to "0", and then proceeds to step S1095, terminating the processing of this routine. In this case, the vehicle 100 is driven in engine drive mode.

[0175] Furthermore, the vehicle driving support system 10 is configured to execute the routine shown in Figure 11 at a predetermined calculation cycle. Therefore, at a predetermined timing, the vehicle driving support system 10 starts processing from step S1100 of the routine shown in Figure 11, proceeds to step S1105, and determines whether or not eco-vehicle speed control is being executed.

[0176] If the vehicle driving support system 10 determines "Yes" in step S1105, it proceeds to step S1110 to determine whether the value of the hybrid drive mode flag X_HV is "1". That is, the vehicle driving support system 10 determines whether the vehicle 100 is currently being driven in hybrid drive mode.

[0177] If the vehicle driving support system 10 determines "Yes" in step S1110, it proceeds to step S1115 to determine whether the eco level LV is high eco level LV_H.

[0178] As shown in Figure 1, the vehicle 100 is equipped with an eco-level setting control device 73, such as an economy level setting button. The eco-level setting control device 73 is electrically connected to the ECU 90. By operating the eco-level setting control device 73, the driver can set the eco-level LV (energy efficiency level) to one of the following: high eco-level LV_H, medium eco-level LV_M, or low eco-level LV_L.

[0179] The Eco Level LV is the level that the driver requests as the level of energy efficiency improvement of the power unit 20 (energy efficiency improvement level). When the Eco Level LV is set to High Eco Level LV_H, the driver requests the maximum energy efficiency improvement level; when the Eco Level LV is set to Low Eco Level LV_L, the driver requests the minimum energy efficiency improvement level; and when the Eco Level LV is set to Medium Eco Level LV_M, the driver requests an energy efficiency improvement level that is smaller than the maximum energy efficiency improvement level but larger than the minimum energy efficiency improvement level.

[0180] As will be described later, the vehicle driving support system 10 sets the set vehicle speed range R_V according to the eco level LV. Generally speaking, the higher the eco level LV, the larger the set vehicle speed range R_V and the set preceding vehicle distance range R_DF of the vehicle driving support system 10. In particular, in this example, the set vehicle speed range R_V and the set preceding vehicle distance range R_DF can be changed by the driver of the vehicle 100 when the vehicle 100 is running in hybrid drive mode.

[0181] If the vehicle driving assistance device 10 determines "Yes" in step S1115, it proceeds to step S1120 to determine whether the rearward detection normal condition C9 is met.

[0182] Rear detection normal condition C9 is met when the rear information detection device 52 is functioning normally and is able to successfully detect the rear detection information IR used to detect the following vehicle 300. Therefore, rear detection normal condition C9 is not met if the rear detection information IR used to detect the following vehicle 300 cannot be detected due to a malfunction of the rear information detection device 52 or other reasons. In addition, rear detection normal condition C9 may also be a condition that is not met if the rear information detection device 52 is not installed on the vehicle 100.

[0183] If the vehicle driving assistance device 10 determines "Yes" in step S1120, it proceeds to step S1125, sets the control vehicle speed width dV to the first vehicle speed width dV1, and then proceeds to step S1195, terminating the processing of this routine. The first vehicle speed width dV1 is set to a value greater than zero and is a relatively large value.

[0184] On the other hand, if the vehicle driving support device 10 determines "No" in step S1120, it proceeds to step S1130, sets the control vehicle speed width dV to the second vehicle speed width dV2, and then proceeds to step S1195, terminating the processing of this routine. The second vehicle speed width dV2 is set to a value greater than zero and less than the first vehicle speed width dV1.

[0185] Thus, the vehicle driving support device 10 is configured to set the set vehicle speed range R_V to a smaller range than when the rear detection normal condition C9 is met (when the control range change condition is met, indicating an abnormality in the following vehicle detection device that detects the following vehicle 300) while eco vehicle speed control (vehicle speed increase / decrease control) is being performed.

[0186] In other words, the vehicle driving support system 10 is configured to set the set vehicle speed range R_V (set control range) to a smaller range than when the rear information detection device 52 (a following vehicle detection device that detects following vehicles 300) is functioning correctly, in the event that an abnormality occurs in the rear information detection device 52 (a following vehicle detection device that detects following vehicles 300) while the vehicle 100 is autonomously driving using eco vehicle speed control in hybrid drive mode (autonomous driving control in first drive mode).

[0187] When the vehicle 100 is autonomously driven using eco-speed control and a following vehicle 300 is present, if the vehicle speed V increases or decreases excessively, the following vehicle 300 will also increase or decrease its speed significantly, potentially hindering the smooth flow of traffic for surrounding vehicles, including the following vehicle 300. Therefore, in order to maintain the smooth flow of traffic for surrounding vehicles, when the vehicle 100 is autonomously driven using eco-speed control and a following vehicle 300 is present, it is desirable to consider the presence of the following vehicle 300 when autonomously driving the vehicle 100 using eco-speed control. However, if a malfunction occurs in the rear information detection device 52 or the following vehicle 300 cannot be detected, eco-speed control cannot be performed considering the presence of the following vehicle 300, and therefore, the vehicle 100 cannot be autonomously driven using eco-speed control in a way that maintains the smooth flow of traffic for surrounding vehicles.

[0188] According to the vehicle driving support system 10, if an abnormality occurs in the rear information detection device 52, the set vehicle speed range R_V is set to a smaller range than when the rear information detection device 52 is functioning normally. This prevents the vehicle speed V from increasing or decreasing excessively. Therefore, even when the following vehicle 300 cannot be detected, the vehicle 100 can be driven autonomously by eco-speed control without interfering with the smooth flow of traffic of surrounding vehicles.

[0189] Furthermore, if the vehicle driving support device 10 determines "No" in step S1115, it proceeds to step S1135 to determine whether the eco level LV is the medium eco level LV_M.

[0190] If the vehicle driving support device 10 determines "Yes" in step S1135, it proceeds to step S1140, sets the control vehicle speed width dV to the second vehicle speed width dV2, and then proceeds to step S1195, terminating the processing of this routine.

[0191] On the other hand, if the vehicle driving support device 10 determines "No" in step S1135, it proceeds to step S1145, sets the control vehicle speed width dV to the third vehicle speed width dV3, and then proceeds to step S1195, terminating the processing of this routine. The third vehicle speed width dV3 is set to a value greater than zero and less than the second vehicle speed width dV2.

[0192] Furthermore, if the vehicle driving support device 10 determines "No" in step S1110, it proceeds to step S1150 to determine whether the value of the motor drive mode flag X_EV is "1".

[0193] If the vehicle driving assistance device 10 determines "Yes" in step S1150, it proceeds to step S1155, sets the control vehicle speed width dV to the fourth vehicle speed width dV4, and then proceeds to step S1195, terminating the processing of this routine. The fourth vehicle speed width dV4 is set to a value greater than zero and less than the third vehicle speed width dV3.

[0194] Thus, the vehicle driving support device 10 is configured to perform eco-speed control (speed increase / decrease control) in a hybrid drive mode (first drive mode) in which power is applied to the vehicle 100 by operating both the internal combustion engine 21 and the electric motor 22 or only the internal combustion engine 21 to drive the vehicle 100, and in a motor drive mode (second drive mode) in which power is applied to the vehicle 100 by operating only the electric motor 22 to drive the vehicle 100.

[0195] Furthermore, the set vehicle speed range R_V is set to a smaller range when eco vehicle speed control (vehicle speed increase / decrease control) is performed in motor drive mode (second drive mode) than when eco vehicle speed control is performed in hybrid drive mode (first drive mode).

[0196] Furthermore, the condition for reducing the controlled vehicle speed range dV includes the condition that eco vehicle speed control (vehicle speed increase / decrease control) is being performed in hybrid drive mode (first drive mode). The vehicle driving support device 10 is configured not to change the set vehicle speed range R_V even if the rear detection normal condition C9 is not met (even if the control range change condition is met) when eco vehicle speed control is being performed in motor drive mode (second drive mode).

[0197] In other words, the vehicle driving support system 10 is configured not to change the controlled vehicle speed range dV (set control range) even if an abnormality occurs in the rear information detection device 52 (following vehicle detection device that detects following vehicles 300) while performing eco vehicle speed control in motor drive mode (autonomous driving control in second drive mode).

[0198] According to the vehicle driving support device 10, when the vehicle 100 is autonomously driving using eco-speed control in motor drive mode, the set speed range R_V is set to a relatively small range. Therefore, even in situations where the following vehicle 300 cannot be detected due to an abnormality in the rear information detection device 52, if the autonomous driving of the vehicle 100 using eco-speed control continues without changing the set speed range R_V, the vehicle speed V will not increase or decrease excessively, and therefore the following vehicle 300 will not increase or decrease its speed significantly. For this reason, the possibility of hindering the smooth flow of traffic for surrounding vehicles is small. Therefore, the vehicle 100 can be autonomously driven using eco-speed control without changing the set speed range R_V, so as to maintain the smooth flow of traffic for surrounding vehicles.

[0199] Furthermore, the vehicle driving support device 10 is configured to set the control vehicle speed range dV (set control range) to a larger range when the drive mode is hybrid drive mode (first drive mode which can use power other than power generated by the power of the energy storage device 41) than when it is motor drive mode (second drive mode which uses only power generated by the power of the energy storage device 41).

[0200] Furthermore, the vehicle driving support device 10 is configured such that when the rear detection normal condition C9 is met (the control range change condition is not met) while performing eco speed control (vehicle speed increase / decrease control) while selectively executing coasting control (power control in the first state) and optimal power control (power control in the second state), the set vehicle speed range R_V is set to a larger range when the vehicle 100 is autonomously driven by eco speed control (vehicle speed increase / decrease control in the first drive mode) in hybrid drive mode than when the vehicle 100 is autonomously driven in the second drive mode by eco speed control (vehicle speed increase / decrease control in the second drive mode) in motor drive mode.

[0201] When autonomous driving control is performed, that is, when the vehicle 100 is driven autonomously by eco-speed control while selectively performing coasting control and optimal acceleration control, when the vehicle 100 is driven autonomously in hybrid drive mode, setting the set speed range R_V to a large range generally results in a greater reduction in energy consumption. However, when the vehicle 100 is driven autonomously in motor drive mode, even if the set speed range R_V is set to a large range, the reduction in energy consumption is not very large, but the risk of hindering the smooth flow of traffic for surrounding vehicles increases.

[0202] According to the vehicle driving support system 10, when the vehicle 100 is autonomously driven by eco-speed control while selectively executing coasting control and optimal power control, and when the rear detection normal condition C9 is met, the set vehicle speed range R_V is set to a larger range when the drive mode is hybrid drive mode than when the drive mode is motor drive mode. Therefore, it is possible to obtain a certain reduction in energy consumption depending on the drive mode while suppressing interference with the smooth flow of traffic of surrounding vehicles.

[0203] On the other hand, if the vehicle driving support device 10 determines "No" in step S1150, it proceeds to step S1160, sets the controlled vehicle speed width dV to zero, and then proceeds to step S1195, terminating the processing of this routine. In this case, since the drive mode is neither hybrid drive mode nor motor drive mode, the engine continuous operation control is executed as described above.

[0204] Furthermore, if the vehicle driving assistance device 10 determines "No" in step S1105, it proceeds to step S1160, sets the controlled vehicle speed width dV to zero, and then proceeds to step S1195 to terminate the processing of this routine. In this case, if there is no preceding vehicle 200, normal vehicle speed control is performed.

[0205] Furthermore, the vehicle driving support system 10 is configured to execute the routine shown in Figure 12 at a predetermined calculation cycle. Therefore, at a predetermined timing, the vehicle driving support system 10 starts processing from step S1200 of the routine shown in Figure 12, proceeds to step S1205, and determines whether or not the eco-autonomous driving condition C3 is met. In other words, the vehicle driving support system 10 determines whether or not eco-autonomous driving control is being executed.

[0206] If the vehicle driving support system 10 determines "Yes" in step S1205, it proceeds to step S1210 to determine whether the value of the hybrid drive mode flag X_HV is "1". In other words, the vehicle driving support system 10 determines whether the drive mode is the hybrid drive mode.

[0207] If the vehicle driving support system 10 determines "Yes" in step S1210, it proceeds to step S1215 to set the optimal force action P_OPT based on the vehicle speed V, and then proceeds to step S1295 to terminate the processing of this routine. In this case, eco-autonomous driving control is executed based on the optimal force action P_OPT set in step S1215.

[0208] On the other hand, if the vehicle driving support system 10 determines "No" in step S1210, it proceeds to step S1220 to determine whether the value of the motor drive mode flag X_EV is "1". In other words, the vehicle driving support system 10 determines whether the drive mode is motor drive mode.

[0209] If the vehicle driving support system 10 determines "Yes" in step S1220, it proceeds to step S1225 to set the optimal force action P_OPT based on the vehicle speed V, and then proceeds to step S1295 to terminate the processing of this routine. In this case, eco-autonomous driving control is executed based on the optimal force action P_OPT set in step S1225.

[0210] On the other hand, if the vehicle driving support system 10 determines "No" in step S1220, it proceeds to step S1230, sets the optimal force action force P_OPT to zero, and then proceeds to step S1295, terminating the processing of this routine. In this case, since the drive mode is neither hybrid drive mode nor motor drive mode, the engine continuous operation control is executed as described above.

[0211] Furthermore, if the vehicle driving support device 10 determines "No" in step S1205, it proceeds to step S1230, sets the optimal force action force P_OPT to zero, and then proceeds to step S1295 to terminate the processing of this routine. In this case, since the eco autonomous driving condition C3 is not met, normal autonomous driving control is executed.

[0212] Furthermore, the vehicle driving support system 10 is configured to execute the routine shown in Figure 13 at a predetermined calculation cycle. Therefore, at a predetermined timing, the vehicle driving support system 10 starts processing from step S1300 of the routine shown in Figure 13, proceeds to step S1305, and determines whether or not the eco-autonomous driving condition C3 is met. In other words, the vehicle driving support system 10 determines whether or not eco-autonomous driving control is currently being executed.

[0213] If the vehicle driving support system 10 determines "Yes" in step S1305, it proceeds to step S1310 to determine whether the value of the hybrid drive mode flag X_HV is "1". That is, the vehicle driving support system 10 determines whether the vehicle 100 is currently being driven in hybrid drive mode.

[0214] If the vehicle driving assistance device 10 determines "Yes" in step S1310, it proceeds to step S1315 to determine whether the rearward detection normal condition C9 is met.

[0215] If the vehicle driving support device 10 determines "Yes" in step S1315, it proceeds to step S1320, sets the controlled inter-vehicle distance width dD to the first inter-vehicle distance width dD1, and then proceeds to step S1395, terminating the processing of this routine. The first inter-vehicle distance width dD1 is set to a value greater than zero and is a relatively large value. In this case, when eco-inter-vehicle distance control is executed, eco-inter-vehicle distance control is executed based on the set vehicle speed range R_V which is set based on the first inter-vehicle distance width dD1.

[0216] On the other hand, if the vehicle driving support device 10 determines "No" in step S1315, it proceeds to step S1325, sets the controlled inter-vehicle distance width dD to the second inter-vehicle distance width dD2, and then proceeds to step S1195, terminating the processing of this routine. The second inter-vehicle distance width dD2 is set to a value greater than zero and smaller than the first inter-vehicle distance width dD1. In this case, when eco-inter-vehicle distance control is executed, the eco-inter-vehicle distance control is executed based on the set vehicle speed range R_V which is set based on the second inter-vehicle distance width dD2, which is smaller than the first inter-vehicle distance width dD1.

[0217] Thus, the vehicle driving support device 10 is configured to set the set preceding vehicle distance range R_DF to a smaller range than when the rear detection normal condition C9 is met (when the control range change condition is met, indicating an abnormality in the following vehicle detection device that detects the following vehicle 300) while performing eco-distance control (distance increase / decrease control).

[0218] In other words, the vehicle driving support system 10 is configured to set the set preceding vehicle distance range R_DF (set control range) to a smaller range than when the rear information detection device 52 (following vehicle detection device that detects following vehicles 300) is functioning correctly, in the event that an abnormality occurs in the rear information detection device 52 (following vehicle detection device that detects following vehicles 300) while the vehicle 100 is autonomously driving using eco-distance control in hybrid drive mode (autonomous driving control in first drive mode).

[0219] When the vehicle 100 is autonomously driven using eco-friendly inter-vehicle distance control and a following vehicle 300 is present, if the distance DF to the preceding vehicle increases or decreases excessively, the following vehicle 300 will also increase or decrease its speed significantly, potentially hindering the smooth flow of traffic for surrounding vehicles, including the following vehicle 300. Therefore, in order to maintain the smooth flow of traffic for surrounding vehicles, when the vehicle 100 is autonomously driven using eco-friendly inter-vehicle distance control and a following vehicle 300 is present, it is desirable to consider the presence of the following vehicle 300 when autonomously driving the vehicle 100 using eco-friendly inter-vehicle distance control. However, if the following vehicle 300 cannot be detected due to an abnormality in the rear information detection device 52, etc., it will not be possible to perform eco-friendly inter-vehicle distance control while considering the presence of the following vehicle 300, and therefore, the vehicle 100 will not be autonomously driven using eco-friendly inter-vehicle distance control in a way that maintains the smooth flow of traffic for surrounding vehicles.

[0220] According to the vehicle driving support system 10, if an abnormality occurs in the rear information detection device 52, the set preceding vehicle distance range R_DF is set to a smaller range than when the rear information detection device 52 is functioning normally. This prevents the preceding vehicle distance DF from increasing or decreasing excessively. Therefore, even if an abnormality occurs in the rear information detection device 52, the vehicle 100 can be driven autonomously by eco-friendly inter-vehicle distance control without disrupting the smooth flow of traffic for surrounding vehicles.

[0221] Furthermore, if the vehicle driving support device 10 determines "No" in step S1310, it proceeds to step S1330 to determine whether the value of the motor drive mode flag X_EV is "1". In other words, the vehicle driving support device 10 determines whether the vehicle 100 is currently being driven in motor drive mode.

[0222] If the vehicle driving support device 10 determines "Yes" in step S1330, it proceeds to step S1335, sets the controlled inter-vehicle distance width dD to the third inter-vehicle distance width dD3, and then proceeds to step S1395, terminating the processing of this routine. The third inter-vehicle distance width dD3 is set to a value greater than zero and smaller than the second inter-vehicle distance width dD2. In this case, when eco-inter-vehicle distance control is executed, the eco-inter-vehicle distance control is executed based on the set vehicle speed range R_V which is set based on the third inter-vehicle distance width dD3, which is smaller than the second inter-vehicle distance width dD2.

[0223] Thus, the vehicle driving support device 10 is configured to perform eco-friendly inter-vehicle distance control (inter-vehicle distance increase / decrease control) in a hybrid drive mode (first drive mode) in which power is applied to the vehicle 100 by operating both the internal combustion engine 21 and the electric motor 22 or only the internal combustion engine 21 to drive the vehicle 100, and in a motor drive mode (second drive mode) in which power is applied to the vehicle 100 by operating only the electric motor 22 to drive the vehicle 100.

[0224] Furthermore, the set preceding vehicle distance range R_DF is set to a smaller range when eco-distance control (distance increase / decrease control) is performed in motor drive mode (second drive mode) than when eco-distance control is performed in hybrid drive mode (first drive mode).

[0225] Furthermore, the condition for reducing the controlled inter-vehicle distance width dD includes the condition that eco inter-vehicle distance control (inter-vehicle distance increase / decrease control) is being performed in hybrid drive mode (first drive mode). The vehicle driving support device 10 is configured not to change the set preceding vehicle distance range R_DF (set inter-vehicle distance range) even if the rear detection normal condition C9 is not met (even if the control range change condition is met) when eco inter-vehicle distance control (inter-vehicle distance increase / decrease control) is being performed in motor drive mode (second drive mode).

[0226] In other words, the vehicle driving support system 10 is configured not to change the controlled inter-vehicle distance width dD (set control range) even if an abnormality occurs in the rear information detection device 52 (following vehicle detection device that detects the following vehicle 300) while eco inter-vehicle distance control is being performed in motor drive mode (second drive mode).

[0227] According to the vehicle driving support system 10, when the vehicle 100 is autonomously driving in motor drive mode with eco-friendly distance control, the set preceding vehicle distance range R_DF is set to a relatively small range. Therefore, even if a following vehicle 300 cannot be detected due to an abnormality in the rear information detection device 52, the preceding vehicle distance DF will not increase or decrease excessively even if the autonomous driving of the vehicle 100 with eco-friendly distance control continues without changing the set preceding vehicle distance range R_DF, and therefore the following vehicle 300 will not significantly increase or decrease its speed. For this reason, the possibility of hindering the smooth flow of traffic for surrounding vehicles is small. Therefore, the vehicle 100 can be autonomously driven with eco-friendly distance control without changing the set preceding vehicle distance range R_DF, so as to maintain the smooth flow of traffic for surrounding vehicles.

[0228] Furthermore, the vehicle driving support device 10 is configured to set the controlled inter-vehicle distance width dD (set control range) to a larger range when the drive mode is hybrid drive mode (first drive mode that can use power other than power generated by the power of the energy storage device 41) than when it is motor drive mode (second drive mode that uses only power generated by the power of the energy storage device 41).

[0229] Furthermore, the vehicle driving support device 10 is configured to set the set preceding vehicle distance range R_DF (set inter-vehicle distance range) to a larger range than when the rear detection normal condition C9 is met (control range change condition is not met) when the vehicle 100 is autonomously driven by eco inter-vehicle distance control (inter-vehicle distance increase / decrease control in the first drive mode) in hybrid drive mode.

[0230] When autonomous driving control is performed, that is, when the vehicle 100 is driven autonomously by eco-friendly distance control while selectively performing coasting control and optimal acceleration control, when the vehicle 100 is driven autonomously in hybrid drive mode, setting the set preceding vehicle distance range R_DF to a large range generally results in a greater reduction in energy consumption. However, when the vehicle 100 is driven autonomously in motor drive mode, even if the set preceding vehicle distance range R_DF is set to a large range, the reduction in energy consumption is not very large, but the risk of hindering the smooth flow of traffic for surrounding vehicles increases.

[0231] According to the vehicle driving support system 10, when the vehicle 100 is autonomously driven by eco-inter-vehicle distance control while selectively executing coasting control and optimal power control, and when the rear detection normal condition C9 is met, the set preceding vehicle distance range R_DF is set to a larger range when the drive mode is hybrid drive mode than when the drive mode is motor drive mode. Therefore, it is possible to obtain a certain reduction in energy consumption depending on the drive mode while suppressing interference with the smooth traffic flow of surrounding vehicles.

[0232] On the other hand, if the vehicle driving support device 10 determines "No" in step S1330, it proceeds to step S1340, sets the controlled inter-vehicle distance width dD to zero, and then proceeds to step S1395, terminating the processing of this routine. In this case, since the drive mode is neither hybrid drive mode nor motor drive mode, the engine continuous operation control is executed as described above.

[0233] Furthermore, if the vehicle driving support device 10 determines "No" in step S1305, it proceeds to step S1340, sets the controlled inter-vehicle distance width dD to zero, and then proceeds to step S1195 to terminate the processing of this routine.

[0234] Furthermore, the present invention is not limited to the embodiments described above, and various modifications can be adopted within the scope of the present invention.

[0235] For example, the vehicle driving support device 10 may be configured to perform eco-speed control if the vehicle speed V increases and reaches the upper limit vehicle speed V_U described later while eco-distance control is being performed.

[0236] Furthermore, as shown in Figure 3(A), if a following vehicle 300 is present, the vehicle driving support device 10 may be configured to accelerate its own vehicle 100 by executing optimal power control when the following vehicle distance DR becomes less than or equal to a predetermined following vehicle distance DR_T, even if the preceding vehicle distance DF is less than the upper limit preceding vehicle distance DF_U during the execution of eco-inter-vehicle distance control. In this case, after starting optimal power control, the vehicle driving support device 10 continues optimal power control until the preceding vehicle distance DF reaches the lower limit preceding vehicle distance DF_L, even if the following vehicle distance DR becomes greater than the predetermined following vehicle distance DR_T.

[0237] Furthermore, if there is a following vehicle 300, the vehicle driving support device 10 may be configured to determine the timing to start optimal power control so that the vehicle 100 does not get too close to the following vehicle 300, taking into consideration the difference between the vehicle speed V and the driving speed of the following vehicle 300 while eco-distance control is being performed.

[0238] Furthermore, as shown in Figure 3(B), if there is a following vehicle 300 in the vicinity of the vehicle 100, the vehicle driving support device 10 may be configured to accelerate the vehicle 100 by executing optimal power control when the distance between the vehicle 100 and the following vehicle 300 (following vehicle distance DR) becomes less than or equal to a predetermined distance (predetermined following vehicle distance DR_T), even if the vehicle speed V is greater than the lower limit vehicle speed V_L during the execution of eco speed control. In this case, after starting optimal power control, the vehicle driving support device 10 will continue optimal power control until the vehicle speed V reaches the upper limit vehicle speed V_U, even if the following vehicle distance DR becomes greater than the predetermined following vehicle distance DR_T.

[0239] Furthermore, if there is a following vehicle 300, the vehicle driving support device 10 may be configured to determine the timing to start optimal power control so that the vehicle 100 does not get too close to the following vehicle 300, taking into consideration the difference between the vehicle speed V and the driving speed of the following vehicle 300 while eco-speed control is being performed. [Explanation of Symbols]

[0240] 10...Vehicle driving assistance system, 20...Power unit, 41...Energy storage device, 52...Rear information detection device, 90...ECU, 100...Own vehicle, 200...Preceding vehicle, 300...Following vehicle

Claims

1. A vehicle driving assistance system comprising a control device configured to perform speed increase / decrease control, which causes the vehicle to autonomously drive itself while increasing or decreasing the vehicle speed within a set speed range, or inter-vehicle distance increase / decrease control, which causes the vehicle to autonomously drive itself while increasing or decreasing the inter-vehicle distance between itself and other vehicles in its vicinity within a set inter-vehicle distance range, or while increasing or decreasing the time required for the vehicle to travel the inter-vehicle distance within a set time range, The control device is configured such that, during the execution of the vehicle speed increase / decrease control or the inter-vehicle distance increase / decrease control, if a control range change condition is met indicating an abnormality in the following vehicle detection device that detects following vehicles, the set vehicle speed range or the set inter-vehicle distance range is set to a smaller range than when the control range change condition is not met. Vehicle driving assistance system.

2. In the vehicle driving support device according to claim 1, The control device is configured to perform speed maintenance control, which causes the vehicle to autonomously drive while maintaining the vehicle speed at a set speed, or distance maintenance control, which causes the vehicle to autonomously drive while maintaining the distance between vehicles at a set distance or while maintaining the time required for the vehicle to travel the distance between vehicles at a set time. The control device is configured such that, while the vehicle speed increase / decrease control is being executed, if the following vehicle detection device is functioning correctly, a following vehicle is detected, and the distance between the following vehicle and the vehicle is less than or equal to a predetermined distance, or if the time required for the vehicle to travel the distance between the following vehicle and the vehicle is less than or equal to a predetermined time, the vehicle speed increase / decrease control is stopped and the vehicle speed maintenance control is executed. If the driving mode switching conditions are met while the inter-vehicle distance increase / decrease control is being executed, the inter-vehicle distance increase / decrease control is stopped and the inter-vehicle distance maintenance control is executed. Vehicle driving assistance system.

3. In the vehicle driving support device according to claim 1, The control device is configured to perform vehicle speed increase / decrease control or inter-vehicle distance increase / decrease control in a first drive mode in which power is applied to the vehicle by operating both the internal combustion engine and the electric motor or only the internal combustion engine to drive the vehicle, and in a second drive mode in which power is applied to the vehicle by operating only the electric motor to drive the vehicle. The set vehicle speed range is set to be smaller when the vehicle speed increase / decrease control is performed in the second drive mode than when the vehicle speed increase / decrease control is performed in the first drive mode. The set inter-vehicle distance range is set to be smaller when the inter-vehicle distance increase / decrease control is performed in the second drive mode than when the inter-vehicle distance increase / decrease control is performed in the first drive mode. The control range change condition includes the condition that the vehicle speed increase / decrease control or the inter-vehicle distance increase / decrease control is being performed in the first drive mode. The control device is configured such that, when performing the vehicle speed increase / decrease control or the inter-vehicle distance increase / decrease control in the second drive mode, it does not change the set vehicle speed range or the set inter-vehicle distance range even if the control range change condition is met. Vehicle driving assistance system.

4. In the vehicle driving support device according to claim 3, The control device is configured to selectively perform power control in a first state in which power generation loss in the vehicle's power unit or power transmission loss from the power unit to the vehicle's drive wheels is reduced, and power control in a second state in which the power unit is mechanically or electrically connected to the drive wheels to apply power to the drive wheels, thereby enabling the vehicle speed increase / decrease control or the inter-vehicle distance increase / decrease control. The control device is configured such that, when the vehicle speed increase / decrease control or inter-vehicle distance increase / decrease control is performed while selectively executing the power control in the first state and the power control in the second state, and the control range change condition is not met, the set vehicle speed range or set inter-vehicle distance range is set to a larger range than when the vehicle is autonomously driven by the vehicle speed increase / decrease control or inter-vehicle distance increase / decrease control in the first drive mode. Vehicle driving assistance system.

5. A vehicle driving assistance method that performs speed increase / decrease control to autonomously drive the vehicle while increasing or decreasing the vehicle speed of the vehicle within a set speed range, or distance increase / decrease control to autonomously drive the vehicle while increasing or decreasing the distance between the vehicle and other vehicles in the vicinity of the vehicle within a set distance range, or while increasing or decreasing the time required for the vehicle to travel the distance within a set time range, A vehicle driving assistance method comprising the step of setting the set vehicle speed range or the set inter-vehicle distance range to a smaller range than when the control range change condition is not met, if a control range change condition is met, such that there is an abnormality in the following vehicle detection device that detects following vehicles, while the vehicle speed increase / decrease control or the inter-vehicle distance increase / decrease control is being performed.

6. A vehicle driving support program that performs speed increase / decrease control to autonomously drive the vehicle while increasing or decreasing the vehicle speed within a set speed range, or distance increase / decrease control to autonomously drive the vehicle while increasing or decreasing the distance between the vehicle and other vehicles in the vicinity within a set distance range, or while increasing or decreasing the time required for the vehicle to travel the distance within a set time range, A vehicle driving assistance program configured to set the set vehicle speed range or the set inter-vehicle distance range to a smaller range than when the control range change condition is not met, if a control range change condition is met, such that there is an abnormality in the following vehicle detection device that detects following vehicles, while the vehicle speed increase / decrease control or the inter-vehicle distance increase / decrease control is being executed.

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