Vehicle driving support device

Abstract

To provide a vehicle driving support device capable of performing constant speed control for controlling a vehicle speed to a set vehicle speed with as high energy efficiency as possible.SOLUTION: The vehicle driving support device 10 executes traveling support control for causing the host vehicle to automatically travel by automatically controlling the acceleration of the host vehicle 100. The travel assist control includes vehicle speed control that automatically controls the acceleration of the host vehicle based on a vehicle speed range including a set vehicle speed such that the vehicle speed of the host vehicle is maintained at the set vehicle speed. The detection device 43 is configured to detect a following-vehicle 200rr. When there is a following vehicle, the vehicle driving support device executes acceleration control for increasing the vehicle speed of the host vehicle when the execution of vehicle speed control is requested and a predetermined condition that the vehicle speed of the host vehicle is lower than the vehicle speed of the following vehicle is satisfied.SELECTED DRAWING: Figure 14

Description

[Technical Field]

[0001] The present invention relates to a vehicle driving assistance device. [Background technology]

[0002] Vehicles equipped with an internal combustion engine and a motor as a drive system that outputs a drive force (vehicle drive force) to be applied to the vehicle are known. In such vehicles, it is possible to arbitrarily select between an HV mode, in which the vehicle drive force is output from both the internal combustion engine and the motor, and an EV mode, in which the vehicle drive force is output from only the motor. Patent Document 1 describes a vehicle that determines whether to select the HV mode or the EV mode so as to maximize the energy efficiency of the drive system when outputting vehicle drive force. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-182629 Summary of the Invention

[0004] There are known vehicles that are configured to perform constant speed control, which automatically controls the acceleration of the vehicle so that the vehicle speed is controlled to a speed set by the driver (set speed). Even when performing this constant speed control, it is desirable to control the acceleration of the vehicle so that the energy efficiency of the drive unit when outputting vehicle driving force is as high as possible.

[0005] An object of the present invention is to provide a vehicle driving assistance device that can perform constant speed control, which controls the vehicle speed to a set vehicle speed, with as high energy efficiency as possible.

[0006] A vehicle driving assistance device according to the present invention includes a control unit that executes driving assistance control to automatically control the acceleration of the host vehicle to automatically drive the host vehicle. The driving assistance control includes a vehicle speed control that automatically controls the acceleration of the host vehicle based on a vehicle speed range including a set vehicle speed so that the vehicle speed of the host vehicle is maintained at the set vehicle speed. The vehicle driving assistance device according to the present invention also includes a detection unit that detects a following vehicle that is traveling within a predetermined following vehicle determination distance behind the host vehicle. The control unit is configured to execute acceleration control to increase the vehicle speed of the host vehicle when the following vehicle is present, if execution of the vehicle speed control is requested, the inter-vehicle distance between the host vehicle and the following vehicle is equal to or greater than a predetermined short distance behind that is shorter than the predetermined following vehicle determination distance, the vehicle speed of the host vehicle is slower than the vehicle speed of the following vehicle, the difference in vehicle speed between the host vehicle and the following vehicle is greater than a predetermined rear approaching vehicle speed, and the vehicle speed of the host vehicle is slower than the upper limit of the vehicle speed range. In addition, in the vehicle driving assistance device of the present invention, the control means can be configured to perform the acceleration control based on the vehicle speed of the host vehicle so that the host vehicle is accelerated at an acceleration that makes the energy efficiency of the drive device of the host vehicle equal to or greater than a predetermined efficiency when the drive device outputs a drive force.

[0007] The vehicle driving assistance device according to the present invention also includes a control means for executing driving assistance control that automatically controls the acceleration of the host vehicle to automatically drive the host vehicle. The driving assistance control includes a first vehicle speed control that automatically controls the acceleration of the host vehicle based on a first vehicle speed range including a set vehicle speed so that the vehicle speed of the host vehicle is maintained at the set vehicle speed, and a second vehicle speed control that automatically controls the acceleration of the host vehicle based on a second vehicle speed range including the set vehicle speed so that the vehicle speed of the host vehicle is maintained at the set vehicle speed. The second vehicle speed range is set to a range wider than the first vehicle speed range. The vehicle driving assistance device according to the present invention also includes a detection device that detects a following vehicle that is a vehicle traveling behind the host vehicle. The control means is configured to execute acceleration control to increase the vehicle speed of the host vehicle when the following vehicle is present, the execution of the second vehicle speed control is requested, the inter-vehicle distance between the host vehicle and the following vehicle is equal to or greater than a predetermined rear close distance that is shorter than the predetermined following vehicle judgment distance, the vehicle speed of the host vehicle is slower than the vehicle speed of the following vehicle, the difference in vehicle speed between the host vehicle and the following vehicle is greater than a predetermined rear approach vehicle speed, and the vehicle speed of the host vehicle is slower than the upper limit value of the second vehicle speed range.

[0008] Furthermore, in the vehicle driving assistance device of the present invention, the control means may be configured to execute the acceleration control regardless of the vehicle speed difference between the host vehicle and the following vehicle when execution of the second vehicle speed control is requested, the inter-vehicle distance is smaller than the specified rear close distance, and the vehicle speed of the host vehicle is slower than the upper limit value of the second vehicle speed range.

[0009] Furthermore, in the vehicle driving assistance device of the present invention, the control means may be configured to execute the first vehicle speed control when the inter-vehicle distance is smaller than the specified rear close distance and the vehicle speed of the host vehicle is equal to or greater than the upper limit value of the second vehicle speed range, even if execution of the second vehicle speed control is requested. Furthermore, in the vehicle driving assistance device according to the present invention, the control means may be configured to execute control to coast the host vehicle when decelerating the host vehicle during execution of the second vehicle speed control.

[0010] 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, features, and attendant advantages of the present invention will be easily understood from the description of the embodiments of the present invention. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a diagram showing a vehicle driving assistance device according to an embodiment of the present invention and a vehicle (host vehicle) on which the vehicle driving assistance device is installed. [Figure 2] FIG. 2 is a diagram showing the distance between vehicles ahead and behind. [Figure 3] (A) of Figure 3 is a diagram showing the vehicle speed, etc. of the vehicle when normal constant speed control (first constant speed control) is being executed, and (B) of Figure 3 is a diagram showing the vehicle speed, etc. of the vehicle when eco constant speed control (second constant speed control) is being executed. [Figure 4] (A) of Figure 4 is a diagram showing the vehicle speed, etc. of the host vehicle when the first acceleration / deceleration control is executed in a state where the vehicle speed of the host vehicle is faster than the vehicle speed of the preceding vehicle, and (B) of Figure 4 is a diagram showing the vehicle speed, etc. of the host vehicle when the first acceleration / deceleration control is executed in a state where the vehicle speed of the host vehicle is slower than the vehicle speed of the preceding vehicle. [Figure 5] FIG. 5 is a diagram showing the distance between the preceding vehicles and the like when the second acceleration / deceleration control is being executed. [Figure 6] (A) of Figure 6 is a diagram showing the vehicle speed, etc. of the host vehicle when the third acceleration / deceleration control is being executed, and (B) of Figure 6 is a diagram showing the vehicle speed, etc. of the host vehicle when the fourth acceleration / deceleration control is being executed. [Figure 7] FIG. 7 is a diagram showing the energy efficiency of the internal combustion engine, the energy efficiency of the motor, and the required driving force. [Figure 8] FIG. 8 is a flowchart showing a routine executed by the vehicle driving assistance device according to the embodiment of the present invention. [Figure 9] FIG. 9 is a flowchart showing a routine executed by the vehicle driving assistance device according to the embodiment of the present invention. [Figure 10] FIG. 10 is a flowchart showing a routine executed by the vehicle driving assistance device according to the embodiment of the present invention. [Figure 11] FIG. 11 is a flowchart showing a routine executed by the vehicle driving assistance device according to the embodiment of the present invention. [Figure 12] FIG. 12 is a flowchart showing a routine executed by the vehicle driving assistance device according to the embodiment of the present invention. [Figure 13] FIG. 13 is a flowchart showing a routine executed by the vehicle driving assistance device according to the embodiment of the present invention. [Figure 14] FIG. 14 is a flowchart showing a routine executed by the vehicle driving assistance device according to the embodiment of the present invention. [Figure 15] FIG. 15 is a flowchart showing a routine executed by the vehicle driving assistance device according to the embodiment of the present invention. [Figure 16] FIG. 16 is a flowchart showing a routine executed by the vehicle driving assistance device according to the embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, a vehicle driving assistance device according to an embodiment of the present invention will be described with reference to the drawings. Fig. 1 shows a vehicle driving assistance device 10 according to an embodiment of the present invention. The vehicle driving assistance device 10 is mounted on a host vehicle 100.

[0013] <ecu> The vehicle driving assistance device 10 includes an ECU 90. ECU is an abbreviation for electronic control unit. The ECU 90 includes a microcomputer as its main component. The microcomputer includes a CPU, ROM, RAM, non-volatile memory, an interface, and the like. The CPU executes instructions, programs, or routines stored in the ROM to realize various functions.

[0014] <Drive unit, etc.> The host vehicle 100 is equipped with a drive device 21 and a braking device 22 .

[0015] <Drive unit> The drive device 21 is a device that outputs a driving force that is applied to the host vehicle 100 to make the host vehicle 100 travel, and is, for example, an internal combustion engine or a motor. The drive device 21 is electrically connected to the ECU 90. The ECU 90 can control the driving force output from the drive device 21 by controlling the operation of the drive device 21.

[0016] <Brake device> The braking device 22 is a device, such as a brake device, that outputs a braking force to be applied to the host vehicle 100 in order to brake the host vehicle 100. The braking device 22 is electrically connected to the ECU 90. The ECU 90 can control the braking force output from the braking device 22 by controlling the operation of the braking device 22.

[0017] <Front and rear information detection devices, etc.> Furthermore, the vehicle 100 is equipped with an accelerator pedal 31, an accelerator pedal operation amount sensor 32, a brake pedal 33, a brake pedal operation amount sensor 34, a driving assistance operation device 41, an eco-driving operation device 42, a front and rear information detection device 43, and a vehicle speed detection device 44.

[0018] <Accelerator pedal operation amount sensor> The accelerator pedal operation amount sensor 32 is electrically connected to the ECU 90. The accelerator pedal operation amount sensor 32 detects the operation amount of the accelerator pedal 31 and transmits information about the detected operation amount to the ECU 90. Based on that information, the ECU 90 obtains the operation amount of the accelerator pedal 31 as the accelerator pedal operation amount AP.

[0019] When the accelerator pedal operation amount AP is greater than zero, the ECU 90 calculates the required driving force Pd_req from the accelerator pedal operation amount AP and the vehicle speed Vown of the host vehicle 100. The required driving force Pd_req is the driving force that is required to be output from the drive device 21. The ECU 90 controls the operation of the drive device 21 so that the required driving force Pd_req is output.

[0020] <Brake pedal operation amount sensor> The brake pedal operation amount sensor 34 is electrically connected to the ECU 90. The brake pedal operation amount sensor 34 detects the operation amount of the brake pedal 33 and transmits information about the detected operation amount to the ECU 90. Based on that information, the ECU 90 obtains the operation amount of the brake pedal 33 as the brake pedal operation amount BP.

[0021] When the brake pedal operation amount BP is greater than zero, the ECU 90 calculates and obtains a required braking force Pb_req from the brake pedal operation amount BP. The required braking force Pb_req is a braking force that is required to be output from the braking device 22. The ECU 90 controls the operation of the braking device 22 so that the required braking force Pb_req is output.

[0022] <Driving assistance control device> The driving assistance operating device 41 is a device operated by the driver of the vehicle 100. The driving assistance operating device 41 is a device including switches, buttons, etc. These switches, buttons, etc. are provided, for example, on the steering wheel of the vehicle 100, or on a lever attached to the steering column of the vehicle 100.

[0023] In this example, the driving assistance operation device 41 includes a driving assistance selection switch, a vehicle speed setting switch, a vehicle speed increase button, a vehicle speed decrease button, and a vehicle distance setting button. The driving assistance operation device 41 is electrically connected to the ECU 90.

[0024] When the driver operates the driving assistance selection switch while driving assistance control, which will be described later, is not being executed, a signal is transmitted from the driving assistance operation device 41 to the ECU 90. When the ECU 90 receives this signal, it determines that the driver is requesting the execution of driving assistance control.

[0025] On the other hand, if the driver operates the driving assistance selection switch while driving assistance control is being executed, a signal is transmitted from driving assistance operation device 41 to ECU 90. When ECU 90 receives this signal, it determines that the driver is requesting the end of driving assistance control.

[0026] Furthermore, when the driver operates the vehicle speed setting switch while the cruise assist control is being executed, a signal is transmitted from the cruise assist operation device 41 to the ECU 90. When the ECU 90 receives the signal, it sets the vehicle speed Vown of the host vehicle 100 at that time as the set vehicle speed Vset for the cruise assist control.

[0027] Furthermore, if the driver operates the vehicle speed increase button while driving assist control is being executed, a signal is sent from the driving assist operation device to the ECU 90. When the ECU 90 receives this signal, it increases the set vehicle speed Vset. On the other hand, when the driver operates the vehicle speed decrease button while driving assist control is being executed, a signal is sent from the driving assist operation device 41 to the ECU 90. When the ECU 90 receives this signal, it decreases the set vehicle speed Vset.

[0028] Furthermore, when the driver operates the inter-vehicle distance setting button while cruise assist control is being executed, a signal is transmitted from cruise assist operation device 41 to ECU 90. This signal is a signal (requested inter-vehicle distance signal) that indicates the distance (requested front inter-vehicle distance Dfr_req) that the driver requests as the distance (front inter-vehicle distance Dfr) between host vehicle 100 and preceding vehicle 200fr in the following cruise control of cruise assist control by operating the inter-vehicle distance setting button.

[0029] The forward inter-vehicle distance Dfr is the distance between the host vehicle 100 and the preceding vehicle 200fr, as shown in Fig. 2. In this example, the preceding vehicle 200fr is a vehicle traveling ahead of the host vehicle 100 in the lane in which the host vehicle 100 is traveling (host lane LN), and whose distance from the host vehicle 100 (forward inter-vehicle distance Dfr) is equal to or less than a predetermined preceding vehicle determination distance Dfr_th.

[0030] In this example, the required forward inter-vehicle distance Dfr_req that the driver can select by operating the inter-vehicle distance setting button has three types: a long distance, a medium distance, and a short distance.

[0031] When the ECU 90 receives a required inter-vehicle distance signal, it may set the distance requested as the required inter-vehicle distance Dfr_req as the set inter-vehicle distance Dfr_set without taking into account the vehicle speed Vown of the vehicle 100 at that time. However, in this example, the set inter-vehicle distance Dfr_set is set based on the vehicle speed Vown and the required inter-vehicle distance Dfr_req at that time.

[0032] Specifically, the ECU 90 sets the front inter-vehicle distance Dfr, which is obtained by dividing the time (estimated arrival time TTC) obtained by dividing by the current vehicle speed Vown, to a predetermined time (predetermined predicted arrival time TTCref), as the set front inter-vehicle distance Dfr_set. That is, the ECU 90 sets the front inter-vehicle distance Dfr, which satisfies the relationship between the current vehicle speed Vown, the predetermined predicted arrival time TTCref, and the front inter-vehicle distance Dfr, as the set front inter-vehicle distance Dfr_set.

[0033] TTCref=Dfr / Vown …(1)

[0034] The predetermined predicted arrival time TTCref is a longer time TTClong when the required forward inter-vehicle distance Dfr_req is a longer distance, a medium time TTCmid when the required forward inter-vehicle distance Dfr_req is a medium distance, and a shorter time TTCshort when the required forward inter-vehicle distance Dfr_req is a shorter distance.

[0035] The predetermined preceding vehicle determination distance Dfr_th is set to be longer than the set preceding vehicle distance Dfr_set.

[0036] <Eco-driving control device> The eco-traveling operation device 42 is a device operated by the driver of the host vehicle 100. The eco-traveling operation device 42 is a device made up of switches, buttons, etc. These switches, buttons, etc. are provided, for example, on the steering wheel of the host vehicle 100, or on a lever attached to the steering column of the host vehicle 100.

[0037] When the eco-driving operation device 42 is operated while it is in the OFF position, it changes to the ON position. When the eco-driving operation device 42 is operated to the ON position, it transmits a specific signal to the ECU 90. When the ECU 90 receives this signal, it determines that the driver has requested the execution of eco constant speed control (second constant speed control), which will be described later. When the ECU 90 determines that the driver has requested the execution of eco constant speed control (second constant speed control), it determines that the eco-driving condition Ceco is met.

[0038] On the other hand, when the eco-driving operation device 42 is operated while it is in the ON position, it is set to the OFF position. When the eco-driving operation device 42 is operated to the OFF position, it transmits a specific signal to the ECU 90. When the ECU 90 receives this signal, it determines that the driver has not requested that eco constant speed control (second constant speed control) be performed. When the ECU 90 determines that the driver has not requested that eco constant speed control (second constant speed control) be performed, it determines that the eco-driving condition Ceco is not met.

[0039] <Front and rear information detection device> The front-rear information detection device 43 is a device that detects information in front of and behind the host vehicle 100. The front-rear information detection device 43 is, for example, a device such as a camera, a radar sensor (such as a millimeter wave radar), an ultrasonic sensor (clearance sonar), or a laser radar (LiDAR).

[0040] The front-rear information detection device 43 is electrically connected to the ECU 90. The front-rear information detection device 43 transmits information ahead of the host vehicle 100 (front information) and information behind the host vehicle 100 (rear information) to the ECU 90. The ECU 90 acquires the distance between the preceding vehicle 200fr and the host vehicle 100 (front inter-vehicle distance Dfr), the vehicle speed Vfr of the preceding vehicle 200fr, and the like from the front information. In addition, the ECU 90 acquires the distance between the following vehicle 200rr and the host vehicle 100 (rear inter-vehicle distance Drr), the vehicle speed Vrr of the following vehicle 200rr, and the like from the rear information.

[0041] The rear inter-vehicle distance Drr is the distance between the host vehicle 100 and the following vehicle 200rr, as shown in Fig. 2. In this example, the following vehicle 200rr is a vehicle traveling behind the host vehicle 100 in the lane in which the host vehicle 100 is traveling (host lane LN), and whose distance from the host vehicle 100 (rear inter-vehicle distance Drr) is equal to or less than a predetermined following vehicle determination distance Drr_th.

[0042] <Vehicle speed detection device> The vehicle speed detection device 44 is a device that detects the vehicle speed Vown of the host vehicle 100, and is, for example, a wheel speed sensor. The vehicle speed detection device 44 is electrically connected to the ECU 90. The vehicle speed detection device 44 detects the vehicle speed Vown of the host vehicle 100, and transmits information about the vehicle speed Vown to the ECU 90. The ECU 90 acquires the vehicle speed Vown based on the information.

[0043] <Outline of operation of vehicle driving assistance devices> Next, an overview of the operation of the vehicle driving assistance device 10 will be described. The vehicle driving assistance device 10 executes driving assistance control when execution of driving assistance control is requested. The driving assistance control includes normal driving assistance control and eco-driving assistance control. The normal driving assistance control includes follow-up driving control and normal constant speed control (first constant speed control), and the eco-driving assistance control includes eco-constant speed control (second constant speed control), first acceleration / deceleration control, second acceleration / deceleration control, third acceleration / deceleration control, and fourth acceleration / deceleration control.

[0044] <Normal driving assistance control> The vehicle driving support device 10 executes normal driving support control when the driving support execution condition Cacc is met but the eco-driving condition Ceco is not met.

[0045] The vehicle driving assistance device 10 may be configured to determine that the driving assistance execution condition Cacc is met when it is determined that the driver has requested the execution of driving assistance control, regardless of whether the accelerator pedal 31 or the brake pedal 33 is being operated by the driver. In this example, however, if it is determined that the driver has requested the execution of driving assistance control and neither the accelerator pedal 31 nor the brake pedal 33 is being operated by the driver, it is determined that the driving assistance execution condition Cacc is met.

[0046] Furthermore, if the vehicle driving assistance device 10 determines that the driver has requested the end of driving assistance control while driving assistance control is being executed, it determines that the driving assistance execution condition Cacc has not been satisfied, that is, that the condition for terminating driving assistance control (driving assistance control termination condition Cend) has been satisfied. Furthermore, the vehicle driving assistance device 10 also determines that the driving assistance execution condition Cacc has not been satisfied if the driver operates the accelerator pedal 31 or the brake pedal 33 while driving assistance control is being executed.

[0047] When a preceding vehicle 200fr is present, the vehicle driving assistance device 10 executes follow-up cruise control as normal cruise assistance control. Note that the vehicle driving assistance device 10 determines that a preceding vehicle 200fr is present when a vehicle traveling ahead of the host vehicle 100 in the host vehicle lane LN has a preceding vehicle distance Dfr that is equal to or less than a predetermined preceding vehicle determination distance Dfr_th.

[0048] On the other hand, when the preceding vehicle 200fr does not exist, the vehicle driving assistance device 10 executes normal constant speed control (first constant speed control) as normal driving assistance control.

[0049] The vehicle driving assistance system 10 determines that a preceding vehicle 200fr is present when the distance Dfr between the preceding vehicles is equal to or less than a predetermined preceding vehicle determination distance Dfr_th.

[0050] <Follow-up driving control> When performing follow-up driving control, the vehicle driving assistance device 10 accelerates or decelerates the host vehicle 100 so that the forward inter-vehicle distance Dfr is maintained at the set forward inter-vehicle distance Dfr_set, in other words, so that the predicted arrival time TTC is maintained at a predetermined predicted arrival time TTCref.

[0051] In this example, when performing follow-up cruise control, the vehicle driving assistance device 10 calculates, as the required acceleration Greq, the acceleration G of the host vehicle 100 required to control the predicted arrival time TTC to the predetermined predicted arrival time TTCref. At this time, the vehicle driving assistance device 10 calculates the required acceleration Greq so that the speed at which the predicted arrival time TTC converges to the predetermined predicted arrival time TTCref (convergence speed) is equal to or greater than a predetermined speed.

[0052] Then, the vehicle driving assistance device 10 calculates the required driving force Pd_req or the required braking force Pb_req to achieve the required acceleration Greq, and controls the operation of the driving device 21 and / or the braking device 22 so that the required driving force Pd_req or the required braking force Pb_req is output, thereby accelerating or decelerating the host vehicle 100. Therefore, as described above, the vehicle driving assistance device 10 calculates the required acceleration Greq so that the speed at which the predicted arrival time TTC converges to the predetermined predicted arrival time TTCref is equal to or greater than the predetermined speed, and as a result, acceleration and deceleration are performed so that the speed at which the predicted arrival time TTC converges to the predetermined predicted arrival time TTCref is equal to or greater than the predetermined speed.

[0053] <Normal constant speed control (first constant speed control)> Furthermore, when performing normal constant speed control (first constant speed control), the vehicle driving assistance device 10 accelerates or decelerates the host vehicle 100 so that the vehicle speed Vown of the host vehicle 100 is maintained at the set vehicle speed Vset. Specifically, as shown in (A) of Fig. 3, when the vehicle speed Vown decreases and falls below the set vehicle speed Vset, the vehicle driving assistance device 10 accelerates the host vehicle 100 to increase the vehicle speed Vown, and when the vehicle speed Vown increases and exceeds the set vehicle speed Vset, the vehicle driving assistance device 10 decelerates the host vehicle 100 to decrease the vehicle speed Vown.

[0054] In this example, when performing normal constant speed control, the vehicle driving assistance device 10 calculates the acceleration G of the host vehicle 100 required to control the vehicle speed Vown of the host vehicle 100 to the set vehicle speed Vset as the required acceleration Greq. At this time, the vehicle driving assistance device 10 calculates the required acceleration Greq so that the speed at which the vehicle speed Vown of the host vehicle 100 converges to the set vehicle speed Vset (convergence speed) is equal to or greater than a predetermined speed.

[0055] The vehicle driving assistance device 10 then calculates the required driving force Pd_req or the required braking force Pb_req to achieve the required acceleration Greq, and controls the operation of the driving device 21 and / or the braking device 22 so that the required driving force Pd_req or the required braking force Pb_req is output, thereby accelerating or decelerating the host vehicle 100. Therefore, as described above, the vehicle driving assistance device 10 calculates the required acceleration Greq so that the speed at which the vehicle speed Vown of the host vehicle 100 converges to the set vehicle speed Vset is equal to or greater than a predetermined speed, and as a result, the host vehicle 100 accelerates and decelerates so that the speed at which the vehicle speed Vown of the host vehicle 100 converges to the set vehicle speed Vset is equal to or greater than the predetermined speed.

[0056] In this example, when performing normal constant speed control (first constant speed control), the vehicle driving assistance device 10 accelerates or decelerates the host vehicle 100 based on the set vehicle speed Vset. However, for example, the vehicle driving assistance device 10 may be configured to determine a vehicle speed range (first vehicle speed range R1) including the set vehicle speed Vset as a criterion for determining whether to accelerate or decelerate the host vehicle 100 in accordance with the set vehicle speed Vset, and to accelerate the host vehicle 100 to increase the vehicle speed Vown when the vehicle speed Vown decreases and falls below a lower limit value Vlow1 of the first vehicle speed range R1, and to decelerate the host vehicle 100 to decrease the vehicle speed Vown when the vehicle speed Vown increases and exceeds an upper limit value Vup1 of the first vehicle speed range R1. In this way, the average vehicle speed Vave (average value of the vehicle speed Vown) of the host vehicle 100 is controlled to be near the set vehicle speed Vset.

[0057] <Eco-driving support control> On the other hand, if the eco-driving condition Ceco is satisfied when the driving support execution condition Cacc is satisfied, the vehicle driving support device 10 executes the eco-driving support control. At this time, the vehicle driving support device 10 executes the eco-driving support control according to the presence or absence of the preceding vehicle 200fr and the presence or absence of the following vehicle 200rr.

[0058] <Eco constant speed control (second constant speed control)> When eco-driving support control is executed and neither the preceding vehicle 200fr nor the following vehicle 200rr is present, the vehicle driving support device 10 executes eco-constant speed control (second constant speed control) as eco-driving support control.

[0059] When performing eco-constant speed control (second constant speed control), the vehicle driving assistance device 10 determines a vehicle speed range (second vehicle speed range R2) including the set vehicle speed Vset as a criterion for determining whether to accelerate or decelerate the vehicle 100, depending on the set vehicle speed Vset.

[0060] 3B, when the vehicle speed Vown decreases and falls below the lower limit value Vlow2 of the second vehicle speed range R2, the vehicle driving assistance device 10 accelerates the host vehicle 100 to increase the vehicle speed Vown, and when the vehicle speed Vown increases and exceeds the upper limit value Vup2 of the second vehicle speed range R2, the vehicle driving assistance device 10 decelerates the host vehicle 100 to decrease the vehicle speed Vown. In this way, the average vehicle speed Vave (average value of the vehicle speed Vown) of the host vehicle 100 is controlled to be close to the set vehicle speed Vset.

[0061] In this example, the second vehicle speed range R2 is set to a wider range than the first vehicle speed range R1. Furthermore, when the set vehicle speed Vset is the same, the upper limit value Vup2 of the second vehicle speed range R2 is set to a value greater than the upper limit value Vup1 of the first vehicle speed range R1, and the lower limit value Vlow2 of the second vehicle speed range R2 is set to a value smaller than the lower limit value Vlow1 of the first vehicle speed range R1.

[0062] Furthermore, in this example, when the vehicle driving assistance device 10 accelerates the host vehicle 100 during execution of eco-constant speed control (second constant speed control), the vehicle driving assistance device 10 calculates as the required acceleration Greq the acceleration G of the host vehicle 100 at which the energy efficiency of the drive device 21 when outputting the driving force Pd is equal to or greater than a predetermined efficiency, taking into account the vehicle speed Vown of the host vehicle 100 at that time.

[0063] Then, the vehicle driving assistance device 10 calculates a required driving force Pd_req to achieve the required acceleration Greq, and controls the operation of the drive device 21 so that the required driving force Pd_req is output, thereby accelerating the host vehicle 100. Therefore, as described above, the vehicle driving assistance device 10 calculates the required acceleration Greq so that the energy efficiency of the drive device 21 when the drive device 21 outputs the driving force Pd is equal to or higher than a predetermined efficiency, and as a result, the host vehicle 100 is accelerated so that the energy efficiency of the drive device 21 when the drive device 21 outputs the driving force Pd is equal to or higher than the predetermined efficiency.

[0064] On the other hand, when the vehicle driving assistance device 10 decelerates the host vehicle 100 during execution of the eco constant speed control (second constant speed control) of this example, it calculates the acceleration G at which the requested driving force Pd_req becomes zero as the requested acceleration Greq.

[0065] Then, the vehicle driving assistance device 10 calculates a required driving force Pd_req to achieve the required acceleration Greq, and controls the operation of the drive device 21 so that the required driving force Pd_req is output from the drive device 21 (i.e., so that the driving force Pd output from the drive device 21 becomes zero), thereby decelerating the host vehicle 100. In other words, the vehicle driving assistance device 10 causes the host vehicle 100 to coast.

[0066] Furthermore, if the drive device 21 includes a motor, the vehicle driving assistance device 10 may be configured to decelerate the vehicle 100 when executing the eco constant speed control (second constant speed control) of this example by rotating the motor using the running energy of the vehicle 100 to regenerate electricity.

[0067] <Other eco-driving support controls> On the other hand, when the vehicle driving support device 10 executes the eco-driving support control, if the preceding vehicle 200fr exists but the following vehicle 200rr does not, the vehicle driving support device 10 determines whether the distance Dfr between the preceding vehicles is longer than the predetermined mid-range Dfr_mid ahead, which is set to a distance shorter than the predetermined preceding vehicle determination distance Dfr_th.

[0068] <First acceleration / deceleration control> When the vehicle driving assistance device 10 determines that the forward inter-vehicle distance Dfr is longer than the predetermined forward mid-distance Dfr_mid, it executes the first acceleration / deceleration control described below.

[0069] That is, when the first acceleration / deceleration control is executed, the vehicle driving assistance system 10 first determines whether the host vehicle 100 is approaching the preceding vehicle 200fr at a relatively high speed. Specifically, the vehicle driving assistance system 10 determines whether the vehicle speed Vown of the host vehicle 100 is faster than the vehicle speed Vfr of the preceding vehicle 200fr and whether the difference ΔVfr between the vehicle speeds is greater than a predetermined forward approaching vehicle speed difference ΔVfr_a.

[0070] As shown in (A) of Figure 4, when the vehicle driving assistance device 10 determines that the vehicle speed Vown of the host vehicle 100 is faster than the vehicle speed Vfr of the preceding vehicle 200fr and that the difference in vehicle speed ΔVfr between them is greater than the predetermined forward approaching vehicle speed difference ΔVfr_a (time t40 in (A) of Figure 4), it decelerates the host vehicle 100 to reduce the vehicle speed Vown of the host vehicle 100.

[0071] At this time, as described above, the vehicle driving assistance device 10 decelerates the host vehicle 100 by controlling the operation of the drive device 21 so that the host vehicle 100 coasts.

[0072] On the other hand, if the vehicle driving assistance device 10 does not determine that the vehicle speed Vown of the host vehicle 100 is faster than the vehicle speed Vfr of the preceding vehicle 200fr and that the difference in vehicle speed ΔVfr therebetween is greater than the predetermined forward approaching vehicle speed difference ΔVfr_a, the vehicle driving assistance device 10 determines whether the vehicle speed Vown of the host vehicle 100 is very slow and whether the host vehicle 100 is being separated from the preceding vehicle 200fr at a relatively fast speed. Specifically, the vehicle driving assistance device 10 determines whether the vehicle speed Vown of the host vehicle 100 is lower than the lower limit value Vlow2 of the second vehicle speed range R2, whether the vehicle speed Vown of the host vehicle 100 is slower than the vehicle speed Vfr of the preceding vehicle 200fr, and whether the difference in vehicle speed ΔVfr therebetween is greater than the predetermined forward separation vehicle speed difference ΔVfr_b.

[0073] The predetermined forward separating vehicle speed difference ΔVfr_b may be the same value as the predetermined forward approaching vehicle speed difference ΔVfr_a, or may be a different value.

[0074] As shown in (B) of Figure 4, when the vehicle driving assistance device 10 determines that the vehicle speed Vown of the host vehicle 100 is lower than the lower limit value Vlow2 of the second vehicle speed range R2, that the vehicle speed Vown of the host vehicle 100 is slower than the vehicle speed Vfr of the preceding vehicle 200fr, and that the difference ΔVfr between the vehicle speeds is greater than the predetermined forward separation vehicle speed difference ΔVfr_b (time t41 in (B) of Figure 4), the vehicle driving assistance device 10 accelerates the host vehicle 100 to increase the vehicle speed Vown of the host vehicle 100.

[0075] In this case, as described above, the vehicle driving assistance device 10 calculates the acceleration G of the host vehicle 100 such that the energy efficiency of the drive device 21 when outputting the driving force Pd is equal to or greater than a predetermined efficiency, taking into account the vehicle speed Vown of the host vehicle 100 at that time, as the required acceleration Greq.

[0076] Then, the vehicle driving assistance device 10 calculates a required driving force Pd_req to achieve the required acceleration Greq, and accelerates the host vehicle 100 by controlling the operation of the drive device 21 so that the required driving force Pd_req is output.

[0077] On the other hand, if the vehicle driving assistance device 10 does not determine that the vehicle speed Vown of the vehicle 100 is lower than the lower limit value Vlow2 of the second vehicle speed range R2, that the vehicle speed Vown of the vehicle 100 is slower than the vehicle speed Vfr of the preceding vehicle 200fr, and that the difference ΔVfr between the vehicle speeds is greater than the specified forward separation vehicle speed difference ΔVfr_b, the vehicle driving assistance device 10 continues accelerating the vehicle 100 if it is accelerating the vehicle 100, and continues decelerating the vehicle 100 if it is decelerating the vehicle 100.

[0078] <Second acceleration / deceleration control> Furthermore, when the vehicle driving assistance device 10 determines that the forward inter-vehicle distance Dfr is equal to or less than a predetermined forward middle distance Dfr_mid, it executes the second acceleration / deceleration control described below.

[0079] When the second acceleration / deceleration control is executed, the vehicle driving assistance device 10 first determines whether the forward inter-vehicle distance Dfr is longer than a predetermined forward short distance Dfr_short, which is set to a distance shorter than a predetermined forward middle distance Dfr_mid.

[0080] As shown in Figure 5, when the vehicle driving assistance device 10 determines that the forward inter-vehicle distance Dfr is longer than the predetermined forward short distance Dfr_short (before time t50 in Figure 5), it decelerates the host vehicle 100 and reduces the vehicle speed Vown of the host vehicle 100.

[0081] At this time, as described above, the vehicle driving assistance device 10 decelerates the host vehicle 100 by controlling the operation of the drive device 21 so that the host vehicle 100 coasts.

[0082] On the other hand, when the vehicle driving support device 10 determines that the distance Dfr between vehicles ahead is equal to or shorter than the predetermined short distance ahead Dfr_short (time t50 in FIG. 5), the vehicle driving support device 10 executes normal driving support control. At this time, since the preceding vehicle 200fr exists, the vehicle driving support device 10 executes follow-up driving control as normal driving support control.

[0083] <When only a following vehicle is present> Furthermore, when the vehicle driving support device 10 executes the eco-driving support control and there is no preceding vehicle 200fr but there is a following vehicle 200rr, the vehicle driving support device 10 determines whether the following vehicle distance Drr is longer than a predetermined following short distance Drr_short, which is set to a distance shorter than the predetermined following vehicle determination distance Drr_th.

[0084] <Third acceleration / deceleration control> When the vehicle driving assistance device 10 determines that the rear inter-vehicle distance Drr is longer than the predetermined rear short distance Drr_short, it executes the third acceleration / deceleration control described below.

[0085] That is, when the third acceleration / deceleration control is executed, the vehicle driving assistance device 10 first determines whether the following vehicle 200rr is approaching the host vehicle 100 at a relatively high speed and whether an increase in the vehicle speed Vown of the host vehicle 100 is permitted. Specifically, the vehicle driving assistance device 10 determines whether the vehicle speed Vown of the host vehicle 100 is slower than the vehicle speed Vrr of the following vehicle 200rr and the difference between the vehicle speeds ΔVrr is greater than a predetermined rear approaching vehicle speed difference ΔVrr_a and the vehicle speed Vown of the host vehicle 100 is lower than the upper limit value Vup2 of the second vehicle speed range R2.

[0086] As shown in (A) of Figure 6, when the vehicle driving assistance device 10 determines that the vehicle speed Vown of the host vehicle 100 is slower than the vehicle speed Vrr of the following vehicle 200rr, the difference in vehicle speed ΔVrr between the two is greater than the predetermined rear approaching vehicle speed difference ΔVrr_a, and the vehicle speed Vown of the host vehicle 100 is lower than the upper limit value Vup2 of the second vehicle speed range R2 (time t60 in (A) of Figure 6), the vehicle driving assistance device 10 accelerates the host vehicle 100 to increase the vehicle speed Vown of the host vehicle 100.

[0087] In this case, as described above, the vehicle driving assistance device 10 calculates the acceleration G of the host vehicle 100 such that the energy efficiency of the drive device 21 when outputting the driving force Pd is equal to or greater than a predetermined efficiency, taking into account the vehicle speed Vown of the host vehicle 100 at that time, as the required acceleration Greq.

[0088] Then, the vehicle driving assistance device 10 calculates a required driving force Pd_req to achieve the required acceleration Greq, and accelerates the host vehicle 100 by controlling the operation of the drive device 21 so that the required driving force Pd_req is output.

[0089] On the other hand, if the vehicle driving assistance device 10 determines that the vehicle speed Vown of the host vehicle 100 is slower than the vehicle speed Vrr of the following vehicle 200rr and the difference in vehicle speeds ΔVrr is greater than the predetermined rear approaching vehicle speed difference ΔVrr_a and the vehicle speed Vown of the host vehicle 100 is not lower than the upper limit value Vup2 of the second vehicle speed range R2, the vehicle driving assistance device 10 continues accelerating the host vehicle 100 when accelerating the host vehicle 100, and continues decelerating the host vehicle 100 when decelerating the host vehicle 100.

[0090] <Fourth acceleration / deceleration control> Furthermore, when the vehicle driving assistance system 10 determines that the rear inter-vehicle distance Drr is equal to or shorter than the predetermined rear short distance Drr_short, it executes a fourth acceleration / deceleration control, which will be described below.

[0091] That is, when the fourth acceleration / deceleration control is executed, the vehicle driving assistance device 10 first determines whether the vehicle speed Vown of the host vehicle 100 is slower than the upper limit value Vup2 of the second vehicle speed range R2.

[0092] As shown in (B) of Figure 6, when the vehicle driving assistance device 10 determines that the vehicle speed Vown of the host vehicle 100 is slower than the upper limit value Vup2 of the second vehicle speed range R2 (before time t61 in (B) of Figure 6), it accelerates the host vehicle 100 to increase the vehicle speed Vown of the host vehicle 100.

[0093] In this case, as described above, the vehicle driving assistance device 10 calculates the acceleration G of the host vehicle 100 such that the energy efficiency of the drive device 21 when outputting the driving force Pd is equal to or greater than a predetermined efficiency, taking into account the vehicle speed Vown of the host vehicle 100 at that time, as the required acceleration Greq.

[0094] Then, the vehicle driving assistance device 10 calculates a required driving force Pd_req to achieve the required acceleration Greq, and accelerates the host vehicle 100 by controlling the operation of the drive device 21 so that the required driving force Pd_req is output.

[0095] On the other hand, when the vehicle driving assistance device 10 determines that the vehicle speed Vown of the host vehicle 100 is equal to or greater than the upper limit value Vup2 of the second vehicle speed range R2 (time t61 in FIG. 6B), the vehicle driving assistance device 10 executes normal driving assistance control. At this time, since the preceding vehicle 200fr does not exist, the vehicle driving assistance device 10 executes normal constant speed control (first constant speed control) as normal driving assistance control.

[0096] <When there are preceding and following vehicles> Furthermore, even if the eco-driving condition Ceco is satisfied when the driving support execution condition Cacc is satisfied, if there are a preceding vehicle 200fr and a following vehicle 200rr, the vehicle driving support device 10 executes normal driving support control. In this case, since there is a preceding vehicle 200fr, the vehicle driving support device 10 executes follow-up driving control.

[0097] <Effects> The energy efficiency E when the drive unit 21 outputs a driving force has a characteristic of being highest (peaking) when the driving force Pd output by the drive unit 21 is a specific value. For example, if the drive unit 21 includes an internal combustion engine and a motor, as shown in Fig. 7, the energy efficiency Eeng (particularly, fuel efficiency) when the internal combustion engine outputs a driving force is highest when the driving force Pd_eng output by the internal combustion engine is a certain value Pd_a, and the energy efficiency Emotor (particularly, electricity efficiency) when the motor outputs a driving force is highest when the driving force Pd_motor output by the motor is a value Pd_b that is smaller than the above value Pd_a.

[0098] Therefore, the operation of the drive device 21 is controlled to output driving force from the drive device 21, and the greater the degree of freedom in controlling the drive device 21, the more energy-efficiently the drive device 21 can be operated.

[0099] Generally, when controlling the vehicle speed to a specific vehicle speed, controlling the vehicle speed while allowing a wide range of vehicle speed fluctuations increases the degree of control freedom when controlling the operation of the drive unit to output the drive force (vehicle drive force) to the vehicle. As a result, control that results in higher energy efficiency can be selected as control for the drive unit. According to the vehicle driving assistance device 10, two driving assistance controls are provided: normal constant speed control (first constant speed control) based on a set vehicle speed Vset, which has a narrower range of allowable vehicle speed fluctuations, and eco constant speed control (second constant speed control) based on a second vehicle speed range R2, which has a wider range of allowable vehicle speed fluctuations. The eco constant speed control is executed according to the driving state of the host vehicle 100. Therefore, the host vehicle 100 can be driven with higher energy efficiency while controlling the vehicle speed Vown of the host vehicle 100 to be close to the set vehicle speed Vset.

[0100] <Specific operation of the vehicle driving assistance device> Next, a specific operation of the vehicle driving assistance device 10 will be described. The CPU of the ECU 90 of the vehicle driving assistance device 10 executes the routine shown in Fig. 8 every time a predetermined calculation time elapses. Therefore, at a predetermined timing, the CPU starts processing from step 800 in Fig. 8, and proceeds to step 805, where it determines whether the driving assistance execution condition Cacc is satisfied.

[0101] If the CPU determines "Yes" in step 805, it proceeds to step 810 and determines whether the eco-driving condition Ceco is met.

[0102] If the CPU determines "Yes" in step 810, it proceeds to step 815 and determines whether the following vehicle distance Drr is longer than a predetermined following vehicle determination distance Drr_th.

[0103] If the CPU determines "Yes" in step 815, it proceeds to step 820 and executes the routine shown in Fig. 9. Therefore, when the CPU proceeds to step 820, it starts the process from step 900 in Fig. 9, and proceeds to step 905 to determine whether the inter-vehicle distance Dfr is longer than the predetermined preceding vehicle determination distance Dfr_th.

[0104] If the CPU determines "Yes" in step 905, it proceeds to step 910 and executes the eco constant speed control (second constant speed control) by executing the routine shown in Fig. 10. Therefore, when the CPU proceeds to step 910, it starts the process from step 1000 in Fig. 10, and proceeds to step 1005 to determine whether the vehicle speed Vown of the host vehicle 100 is faster than the upper limit value Vup2 of the second vehicle speed range R2.

[0105] If the CPU determines "Yes" in step 1005, the process proceeds to step 1010, where it executes deceleration control to decelerate the host vehicle 100.

[0106] In this example, the deceleration control executed in step 1010 and steps described later is a control for decelerating the host vehicle 100 by controlling the operation of the drive device 21 so that the host vehicle 100 coasts. Therefore, the deceleration control can also be said to be a coasting control.

[0107] Thereafter, the CPU advances the process to step 895 in FIG. 8 via step 1095 and step 995 in FIG. 9, and temporarily ends this routine.

[0108] On the other hand, if the CPU determines "No" in step 1005, it proceeds to step 1015 and determines whether the vehicle speed Vown of the host vehicle 100 is slower than the lower limit value Vlow2 of the second vehicle speed range R2.

[0109] If the CPU determines "Yes" in step 1015, the process proceeds to step 1020, where it executes acceleration control to accelerate the host vehicle 100.

[0110] In this example, the acceleration control executed in step 1020 and steps described later calculates, as the required acceleration Greq, the acceleration G of the host vehicle 100 such that the energy efficiency of the drive device 21 when the drive device 21 outputs the drive force Pd is equal to or greater than a predetermined efficiency, taking into account the vehicle speed Vown of the host vehicle 100 at that time. The vehicle driving assistance device 10 then calculates a required drive force Pd_req to achieve the required acceleration Greq, and controls the operation of the drive device 21 so that the required drive force Pd_req is output, thereby accelerating the host vehicle 100.

[0111] Thereafter, the CPU advances the process to step 895 in FIG. 8 via step 1095 and step 995 in FIG. 9, and temporarily ends this routine.

[0112] On the other hand, if the CPU determines "No" in step 1015, the process proceeds to step 895 in FIG. 8 via step 1095 and step 995 in FIG. 9, and ends this routine for the time being.

[0113] If the CPU determines "No" in step 905 of FIG. 9, the CPU proceeds to step 915 and determines whether the forward inter-vehicle distance Dfr is longer than a predetermined forward mid-distance Dfr_mid.

[0114] If the CPU determines "Yes" in step 915, it proceeds to step 920 and executes the first acceleration / deceleration control by executing the routine shown in Fig. 11. Therefore, when the CPU proceeds to step 920, it starts the processing from step 1100 in Fig. 11, and proceeds to step 1105 to determine whether the vehicle speed Vown of the host vehicle 100 is faster than the vehicle speed Vfr of the preceding vehicle 200fr and whether the difference ΔVfr between the vehicle speeds is greater than a predetermined forward approaching vehicle speed difference ΔVfr_a.

[0115] If the CPU determines "Yes" in step 1105, the process proceeds to step 1110, where it executes deceleration control to decelerate the host vehicle 100.

[0116] Thereafter, the CPU advances the process to step 895 in FIG. 8 via step 1195 and step 995 in FIG. 9, and temporarily ends this routine.

[0117] On the other hand, if the CPU determines "No" in step 1105, it proceeds to step 1115 and determines whether the vehicle speed Vown of the host vehicle 100 is slower than the lower limit value Vlow2 of the second vehicle speed range R2, and whether the vehicle speed Vown of the host vehicle 100 is slower than the vehicle speed Vfr of the preceding vehicle 200fr, and whether the difference in vehicle speed ΔVfr between them is greater than the specified forward separation vehicle speed difference ΔVfr_b.

[0118] If the CPU determines "Yes" in step 1115, the process proceeds to step 1120, where it executes acceleration control to accelerate the host vehicle 100.

[0119] Thereafter, the CPU advances the process to step 895 in FIG. 8 via step 1195 and step 995 in FIG. 9, and temporarily ends this routine.

[0120] On the other hand, if the CPU determines "No" in step 1115, the process proceeds to step 895 in FIG. 8 via step 1195 and step 995 in FIG. 9, and ends this routine for the time being.

[0121] 9, the CPU advances the process to step 925, where it executes the second acceleration / deceleration control by executing the routine shown in FIG. 12. Therefore, when the CPU advances the process to step 925, it starts the process from step 1200 in FIG. 12, advances the process to step 1205, and determines whether the forward inter-vehicle distance Dfr is longer than a predetermined forward short distance Dfr_short.

[0122] If the CPU determines "Yes" in step 1205, the process proceeds to step 1210, where it executes deceleration control to decelerate the host vehicle 100.

[0123] Thereafter, the CPU proceeds to step 895 in FIG. 8 via step 1295 and step 995 in FIG. 9, and temporarily ends this routine.

[0124] On the other hand, if the CPU determines "No" in step 1205, it proceeds to step 1215 and executes follow-up cruise control.

[0125] Thereafter, the CPU advances the process to step 895 in FIG. 8 via step 1295 and step 995 in FIG. 9, and temporarily ends this routine.

[0126] If the CPU determines "No" in step 815 of FIG. 8, the CPU proceeds to step 825 and determines whether the distance Dfr between the preceding vehicles is longer than a predetermined preceding vehicle determination distance Dfr_th.

[0127] If the CPU determines "Yes" in step 825, it proceeds to step 830 and executes eco-driving support control by executing the routine shown in Fig. 13. Therefore, when the CPU proceeds to step 830, it starts the process from step 1300 in Fig. 13, and proceeds to step 1305 to determine whether the following distance Drr is longer than a predetermined following short distance Drr_short.

[0128] If the CPU determines "Yes" in step 1305, it proceeds to step 1310 and executes the third acceleration / deceleration control by executing the routine shown in Fig. 14. Therefore, when the CPU proceeds to step 1310, it starts the processing from step 1400 in Fig. 14, and proceeds to step 1405 to determine whether the vehicle speed Vown of the host vehicle 100 is lower than the upper limit value Vup2 of the second vehicle speed range R2, the vehicle speed Vown of the host vehicle 100 is slower than the vehicle speed Vrr of the following vehicle 200rr, and the difference in vehicle speeds ΔVrr therebetween is greater than a predetermined rear approaching vehicle speed difference ΔVrr_a.

[0129] If the CPU determines "Yes" in step 1405, the process proceeds to step 1410, where it executes acceleration control to accelerate the host vehicle 100.

[0130] Thereafter, the CPU advances the process to step 895 in FIG. 8 via step 1495 and step 1395 in FIG. 13, and temporarily ends this routine.

[0131] On the other hand, if the CPU determines "No" in step 1405, the process proceeds to step 895 in FIG. 8 via step 1495 and step 1395 in FIG. 13, and then ends this routine.

[0132] Furthermore, if the CPU determines "No" in step 1305, it proceeds to step 1315 and executes the fourth acceleration / deceleration control by executing the routine shown in Fig. 15. Therefore, when the CPU proceeds to step 1315, it starts the processing from step 1500 in Fig. 15, and proceeds to step 1505 to determine whether the vehicle speed Vown of the host vehicle 100 is lower than the upper limit value Vup2 of the second vehicle speed range R2.

[0133] If the CPU determines "Yes" in step 1505, the process proceeds to step 1510, where it executes acceleration control to accelerate the host vehicle 100.

[0134] Thereafter, the CPU advances the process to step 895 in FIG. 8 via step 1595 and step 1395 in FIG. 13, and temporarily ends this routine.

[0135] On the other hand, if the CPU determines "No" in step 1505, the process proceeds to step 1515, where it executes normal constant speed control (first constant speed control).

[0136] Thereafter, the CPU advances the process to step 895 in FIG. 8 via step 1595 and step 1395 in FIG. 13, and temporarily ends this routine.

[0137] On the other hand, if the CPU determines "No" in step 825 of FIG. 8, the process proceeds to step 835, where it executes follow-up cruise control.

[0138] Thereafter, the CPU advances the process to step 895 and temporarily ends this routine.

[0139] If the CPU determines "No" in step 810, the CPU proceeds to step 840 and executes normal driving support control by executing the routine shown in Fig. 16. Therefore, when the CPU proceeds to step 840, the CPU starts the process from step 1600 in Fig. 16, and then proceeds to step 1605 to determine whether the inter-vehicle distance Dfr is longer than the predetermined preceding vehicle determination distance Dfr_th.

[0140] If the CPU determines "Yes" in step 1605, the process proceeds to step 1610, where it executes follow-up cruise control.

[0141] Thereafter, the CPU advances the process to step 895 in FIG. 8 via step 1695, and temporarily ends this routine.

[0142] On the other hand, if the CPU determines "No" in step 1605, the process proceeds to step 1615, where it executes normal constant speed control (first constant speed control).

[0143] Thereafter, the CPU advances the process to step 895 in FIG. 8 via step 1695, and temporarily ends this routine.

[0144] If the CPU determines "No" in step 805 of FIG. 8, it advances the process to step 895 and temporarily ends this routine.

[0145] The specific operation of the vehicle driving assistance device 10 has been described above.

[0146] The present invention is not limited to the above-described embodiment, and various modifications can be made within the scope of the present invention.

[0147] For example, when eco-driving support control is executed and there is a preceding vehicle 200fr but no following vehicle 200rr, the vehicle driving support device 10 executes the first acceleration / deceleration control or the second acceleration / deceleration control depending on whether the forward inter-vehicle distance Dfr is longer than the specified forward mid-distance Dfr_mid. However, when eco-driving support control is executed and there is a preceding vehicle 200fr but no following vehicle 200rr, the vehicle driving support device 10 may be configured to execute the first acceleration / deceleration control or the second acceleration / deceleration control regardless of whether the forward inter-vehicle distance Dfr is longer than the specified forward mid-distance Dfr_mid.

[0148] Furthermore, when the vehicle driving assistance device 10 executes the eco-driving assistance control, if there is no preceding vehicle 200fr but there is a following vehicle 200rr, it executes the third acceleration / deceleration control or the fourth acceleration / deceleration control depending on whether the rear inter-vehicle distance Drr is longer than the specified rear short distance Drr_short. However, when the vehicle driving assistance control is executed, if there is no preceding vehicle 200fr but there is a following vehicle 200rr, it may be configured to execute the third acceleration / deceleration control or the fourth acceleration / deceleration control regardless of whether the rear inter-vehicle distance Drr is longer than the specified rear short distance Drr_short. [Explanation of symbols]

[0149] 10...vehicle driving assistance device, 21...drive device, 22...braking device, 41...driving assistance operation device, 42...eco-driving operation device, 43...front / rear information detection device, 44...vehicle speed detection device, 90...host vehicle, 100...host vehicle, 200fr...preceding vehicle, 200rr...following vehicle< / ecu>

Claims

1. A vehicle driving assistance device including a control means for executing driving assistance control to automatically control the acceleration of a host vehicle to cause the host vehicle to automatically drive, the driving assistance control includes a vehicle speed control that automatically controls acceleration of the host vehicle based on a vehicle speed range including a set vehicle speed so that the vehicle speed of the host vehicle is maintained at the set vehicle speed, The vehicle driving assistance device includes a detection device that detects a following vehicle that is traveling within a predetermined following vehicle determination distance behind the host vehicle, The control means is configured to execute acceleration control to increase the vehicle speed of the host vehicle when the following vehicle is present, and when the execution of the vehicle speed control is requested, and the inter-vehicle distance between the host vehicle and the following vehicle is equal to or greater than a predetermined short distance behind that is shorter than the predetermined following vehicle judgment distance, and the vehicle speed of the host vehicle is slower than the vehicle speed of the following vehicle, and the difference in vehicle speed between the host vehicle and the following vehicle is greater than a predetermined approaching vehicle speed, and the vehicle speed of the host vehicle is slower than an upper limit value of the vehicle speed range. Vehicle driving assistance device.

2. The vehicle driving assistance device according to claim 1, The control means is configured to execute the acceleration control based on the vehicle speed of the host vehicle so that the host vehicle is accelerated at an acceleration at which the energy efficiency of the drive device of the host vehicle when the drive device outputs a drive force is equal to or greater than a predetermined efficiency. Vehicle driving assistance device.

3. A vehicle driving assistance device including a control means for executing driving assistance control to automatically control the acceleration of a host vehicle to cause the host vehicle to automatically drive, the driving assistance control includes a first vehicle speed control that automatically controls acceleration of the host vehicle based on a first vehicle speed range including a set vehicle speed so that the vehicle speed of the host vehicle is maintained at the set vehicle speed, and a second vehicle speed control that automatically controls acceleration of the host vehicle based on a second vehicle speed range including the set vehicle speed so that the vehicle speed of the host vehicle is maintained at the set vehicle speed, The second vehicle speed range is set to a range wider than the first vehicle speed range, The vehicle driving assistance device includes a detection device that detects a following vehicle that is traveling within a predetermined following vehicle determination distance behind the host vehicle, The control means is configured to execute acceleration control to increase the vehicle speed of the host vehicle when, in the presence of the following vehicle, execution of the second vehicle speed control is requested, the inter-vehicle distance between the host vehicle and the following vehicle is equal to or greater than a predetermined short distance behind that is shorter than the predetermined following vehicle judgment distance, the vehicle speed of the host vehicle is slower than the vehicle speed of the following vehicle, the difference in vehicle speed between the host vehicle and the following vehicle is greater than a predetermined approaching vehicle speed behind, and the vehicle speed of the host vehicle is slower than an upper limit value of the second vehicle speed range. Vehicle driving assistance device.

4. 4. The vehicle driving assistance device according to claim 3, the control means is configured to execute the acceleration control regardless of a vehicle speed difference between the host vehicle and the following vehicle when execution of the second vehicle speed control is requested, the inter-vehicle distance is shorter than the predetermined short rear distance, and the vehicle speed of the host vehicle is slower than an upper limit value of the second vehicle speed range. Vehicle driving assistance device.

5. 4. The vehicle driving assistance device according to claim 3, The control means is configured to execute the first vehicle speed control when the inter-vehicle distance is shorter than the predetermined short rear distance and the vehicle speed of the host vehicle is equal to or higher than an upper limit value of the second vehicle speed range, even when execution of the second vehicle speed control is requested. Vehicle driving assistance device.

6. 6. The vehicle driving assistance device according to claim 5, The control means is configured to execute control to coast the host vehicle when decelerating the host vehicle during execution of the second vehicle speed control. Vehicle driving assistance device.

Images