Vehicle Driving Assistance Device

Abstract

To provide a vehicle operation support device capable of executing follow-up control so as to reliably reduce energy consumption of a drive device of an own vehicle.SOLUTION: A vehicle operation support device 10: predicts an energy consumption amount when first follow-up control is executed as a first energy consumption amount; predicts an energy consumption amount when second follow-up control is executed as a second energy consumption amount; executes the second follow-up control when the second energy consumption amount is smaller than the first energy consumption amount; and executes the first follow-up control when the second energy consumption amount is equal to or larger than the first energy consumption amount.SELECTED DRAWING: Figure 8

Description

[Technical field]

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

[0002] There is known a vehicle driving support device that performs follow-up control to make the host vehicle follow the preceding vehicle by automatically controlling the acceleration / deceleration of the host vehicle according to the distance (inter-vehicle distance) between the host vehicle and the preceding vehicle. Also, as one of such vehicle driving support devices, there is known a vehicle driving support device that is configured to set a threshold value of the inter-vehicle distance (maximum inter-vehicle distance) for determining whether or not the host vehicle needs to accelerate and a threshold value of the inter-vehicle distance (minimum inter-vehicle distance) for determining whether or not the host vehicle needs to decelerate according to the traveling speed (host vehicle speed) of the host vehicle in order to improve fuel efficiency when the follow-up control is performed, and to accelerate the host vehicle when the inter-vehicle distance becomes large to the maximum inter-vehicle distance and to decelerate the host vehicle by coasting (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 4677945 Summary of the Invention

[0004] According to the vehicle driving assistance device, coasting continues from when the inter-vehicle distance becomes the minimum inter-vehicle distance until it reaches the maximum inter-vehicle distance. That is, the vehicle driving assistance device attempts to improve fuel efficiency by allowing the host vehicle to decelerate by coasting until the inter-vehicle distance becomes relatively large.

[0005] However, when the inter-vehicle distance becomes short, the air resistance experienced by the host vehicle becomes small, and therefore, it is expected that fuel efficiency will improve accordingly. Therefore, if the host vehicle is permitted to decelerate by coasting until the inter-vehicle distance becomes relatively large, as in the above-mentioned vehicle driving assistance device, the host vehicle will coast for a long time, and therefore, fuel efficiency can be improved accordingly. However, since the inter-vehicle distance state continues for a long time, the host vehicle will be subjected to large air resistance, and fuel efficiency may deteriorate accordingly. Therefore, even if the host vehicle is permitted to decelerate by coasting until the inter-vehicle distance becomes relatively large, there is a possibility that fuel efficiency will not necessarily be improved in terms of total fuel efficiency.

[0006] In this way, depending on the running state of the host vehicle, the total fuel consumption may be improved by running the host vehicle with the inter-vehicle distance kept constant, rather than allowing the host vehicle to decelerate by coasting until the inter-vehicle distance becomes long. More generally, depending on the running state of the host vehicle, the amount of energy consumed by the drive device of the host vehicle may be reduced by running the host vehicle with the inter-vehicle distance kept constant, rather than allowing the host vehicle to decelerate by coasting until the inter-vehicle distance becomes long.

[0007] An object of the present invention is to provide a vehicle driving assistance device that can execute tracking control so as to more reliably reduce the amount of energy consumed by a drive device of the host vehicle.

[0008] The vehicle driving assistance device of the present invention is equipped with a control device that executes a first following control that automatically controls the acceleration and deceleration of the host vehicle so that the vehicle distance between the host vehicle and the preceding vehicle is maintained within a first predetermined distance range, thereby causing the host vehicle to travel following the preceding vehicle, and a second following control that automatically accelerates and decelerates the host vehicle so that the host vehicle speed, which is the traveling speed of the host vehicle, is maintained at a speed within a predetermined speed range or so that the vehicle distance is maintained within a second predetermined distance range that is wider than the first predetermined distance range.

[0009] The control device predicts an amount of energy consumed by a drive device of the host vehicle when the first follow-up control is executed as a first consumed energy amount, and predicts the amount of energy consumed when the second follow-up control is executed as a second consumed energy amount. The control device is configured to execute the second follow-up control when the second consumed energy amount is smaller than the first consumed energy amount, and to execute the first follow-up control when the second consumed energy amount is equal to or larger than the first consumed energy amount.

[0010] When the host vehicle is caused to follow a preceding vehicle, the air resistance experienced by the host vehicle is reduced, and the amount of energy consumed by the drive device of the host vehicle (the amount of energy consumed by the drive device) is accordingly reduced. Therefore, if the air resistance experienced by the host vehicle is not taken into consideration, the amount of energy consumed by the drive device of the host vehicle is less when the host vehicle is caused to follow the second follow control than when the host vehicle is caused to follow the first follow control; however, when the host vehicle is caused to follow the second follow control, the inter-vehicle distance increases or decreases, and as a result, the air resistance experienced by the host vehicle also increases or decreases. Therefore, if the air resistance experienced by the host vehicle is taken into consideration, it is not necessarily the case that the amount of energy consumed by the drive device is less when the host vehicle is caused to follow the second follow control than when the host vehicle is caused to follow the first follow control.

[0011] According to the present invention, when execution of the second follow-up control is requested, the amount of energy consumed by the drive device when the first follow-up control is executed (first consumed energy amount) and the amount of energy consumed by the drive device when the second follow-up control is executed (second consumed energy amount) are predicted, and the second follow-up control is executed only when the second consumed energy amount is smaller than the first consumed energy amount. Therefore, the amount of energy consumed by the drive device can be reduced. Furthermore, in the vehicle driving assistance device of the present invention, the second following control is a control that, when accelerating the host vehicle, accelerates the host vehicle by optimal acceleration control, which operates the drive device at an operating point where the amount of energy consumed by the drive device is minimum or approximately minimum, to accelerate the host vehicle, and, when decelerating the host vehicle, decelerates the host vehicle by coasting control, which causes the host vehicle to coast. According to the present invention, when the vehicle accelerates, the drive device is operated at an operating point where the amount of energy consumed is minimum or nearly minimum, and when the vehicle decelerates, the vehicle is allowed to coast, thereby making it possible to reduce the amount of energy consumed by the drive device. Alternatively, in the vehicle driving assistance device according to the present invention, the control device is configured to execute a third following control for accelerating or decelerating the host vehicle in synchronization or approximately synchronization with the acceleration and deceleration of the preceding vehicle, thereby causing the host vehicle to run following the preceding vehicle, and when accelerating the host vehicle, the control device executes the third following control for accelerating the host vehicle by optimal acceleration control that operates the drive device of the host vehicle at an operating point where the amount of energy consumed by the drive device is minimum or approximately minimum to accelerate the host vehicle, and when decelerating the host vehicle, the control device executes the third following control for decelerating the host vehicle by coasting control that causes the host vehicle to coast. A request has been made to reduce the amount of energy consumed by the drive device of the vehicle. The control device is configured to execute the third following control when a synchronization condition is satisfied, in which the power output characteristics of the drive unit of the preceding vehicle are the same or substantially the same as the power output characteristics of the drive unit of the host vehicle and the preceding vehicle is traveling under the same control as the second following control or the third following control. On the other hand, the control device is configured to execute the first following control or the second following control when the predetermined execution condition is satisfied but the synchronization condition is not satisfied. When the power output characteristics of the drive device of the preceding vehicle are the same or nearly the same as the power output characteristics of the drive device of the host vehicle and the preceding vehicle is running under the same control as the third following control, the amount of energy consumed by the drive device is less if the host vehicle is running under the third following control, which accelerates and decelerates the host vehicle in synchronization or nearly synchronization with the acceleration and deceleration of the preceding vehicle, than if the host vehicle is running under the first following control or the second following control. According to the present invention, when the power output characteristics of the drive device of the preceding vehicle are the same or nearly the same as the power output characteristics of the drive device of the host vehicle and the preceding vehicle is running under the same control as the third following control, the host vehicle is run under the third following control, so that the amount of energy consumed by the drive device can be reduced. Alternatively, in the vehicle driving support device according to the present invention, the control device is configured to execute a third following control for accelerating or decelerating the host vehicle in synchronization or approximately synchronization with the acceleration and deceleration of the preceding vehicle, and when accelerating the host vehicle, the control device executes the third following control for accelerating the host vehicle by an optimal acceleration control for accelerating the host vehicle by operating the drive device of the host vehicle at an operating point where the amount of energy consumed by the drive device is minimum or approximately minimum, and when decelerating the host vehicle, the control device executes the third following control for decelerating the host vehicle by a coasting control for coasting the host vehicle.Furthermore, when the control device detects another vehicle equipped with a drive device having a power output characteristic that is the same or approximately the same as the power output characteristic of the drive device of the host vehicle and the other vehicle is running under the same control as the second following control or the third following control, the control device is configured to move the host vehicle behind the other vehicle and execute the third following control. According to the present invention, when another vehicle equipped with a drive unit having power output characteristics that are the same or approximately the same as the power output characteristics of the drive unit of the host vehicle is detected, the host vehicle is moved behind the other vehicle and driven using the third following control, thereby reducing the amount of energy consumed by the drive unit of the host vehicle. In the vehicle driving assistance device according to the present invention, the control device may be configured to take into consideration a size of the preceding vehicle when predicting the first amount of consumed energy and the second amount of consumed energy. The air resistance experienced by the vehicle varies depending on the size of the preceding vehicle. According to the present invention, the size of the preceding vehicle is taken into consideration in predicting the first and second consumed energy amounts, so that the first and second consumed energy amounts can be predicted more accurately. Furthermore, in the vehicle driving assistance device according to the present invention, the control device is configured to predict the vehicle distance and the vehicle speed when the first following control is executed based on the traveling speed of the preceding vehicle when the first following control is executed, and to predict the vehicle distance and the vehicle speed when the second following control is executed based on the traveling speed of the preceding vehicle when the second following control is executed. When the first following control and the second following control are executed, the inter-vehicle distance and the host vehicle speed change under the influence of the traveling speed of the preceding vehicle. According to the present invention, the inter-vehicle distance and the host vehicle speed when the first following control is executed are predicted based on the traveling speed of the preceding vehicle when the first following control is executed, and the inter-vehicle distance and the host vehicle speed when the second following control is executed are predicted based on the traveling speed of the preceding vehicle when the second following control is executed, so that the inter-vehicle distance and the host vehicle speed can be predicted more accurately.

[0012] In addition, in the vehicle driving assistance device of the present invention, the control device is configured, for example, when a predetermined execution condition is met that a reduction in the amount of energy consumed by the drive device of the vehicle is requested, to predict changes in the inter-vehicle distance and the vehicle speed when the first following control is executed, and to predict the amount of energy consumed by the drive device of the vehicle when the first following control is executed as the first consumed energy amount based on the inter-vehicle distance and the vehicle speed when it is assumed that they have changed as predicted, and to predict changes in the inter-vehicle distance and the vehicle speed when the second following control is executed, and to predict the amount of energy consumed when the second following control is executed as the second consumed energy amount based on the inter-vehicle distance and the vehicle speed when it is assumed that they have changed as predicted.

[0013] According to the present invention, as described above, when execution of the second tracking control is requested, the first and second consumed energy amounts are predicted, and the second tracking control is executed only when the second consumed energy amount is smaller than the first consumed energy amount, thereby making it possible to reduce the amount of energy consumed by the drive device.

[0014] In addition, in the vehicle driving assistance device of the present invention, the second following control is, for example, a control that decelerates the host vehicle by coasting the host vehicle when the host vehicle speed increases and reaches an upper limit of the predetermined speed range, and accelerates the host vehicle when the host vehicle speed decreases and reaches a lower limit of the predetermined speed range, or accelerates the host vehicle when the inter-vehicle distance increases and reaches an upper limit of the predetermined distance range, and decelerates the host vehicle by coasting the host vehicle when the inter-vehicle distance decreases and reaches a lower limit of the predetermined distance range.

[0015] According to the present invention, when the second tracking control is executed, the vehicle speed is allowed to increase or decrease within a predetermined speed range, or the vehicle distance is allowed to increase or decrease within a predetermined distance range, thereby accelerating or decelerating the vehicle, thereby making it possible to reduce the amount of energy consumed by the drive system.

[0018] In addition, in the vehicle driving assistance device of the present invention, the control device may be configured to set the range of the vehicle speed that is permissible depending on the driving environment of the vehicle as the specified speed range, or to set the range of the inter-vehicle distance that is permissible depending on the driving environment of the vehicle as the specified distance range.

[0019] When the second following control is performed, if the host vehicle speed becomes excessively slow or the vehicle distance becomes excessively long, this is undesirable as it may cause traffic congestion. Also, when the second following control is performed, if the host vehicle speed becomes excessively fast or the vehicle distance becomes excessively short, this is undesirable from the viewpoint of the traveling safety of the host vehicle. The allowable range of the host vehicle speed and the allowable range of the vehicle distance when the second following control is performed vary depending on the traveling environment of the host vehicle. According to the present invention, the predetermined speed range or the predetermined distance range is set depending on the traveling environment of the host vehicle, so that the host vehicle can be made to travel in a more appropriate manner by the second following control.

[0028] Furthermore, the present invention provides a vehicle driving assistance method for driving the host vehicle using a first following control in which the acceleration and deceleration of the host vehicle is automatically controlled so that the inter-vehicle distance between the host vehicle and the preceding vehicle is maintained at a predetermined distance, thereby causing the host vehicle to follow the preceding vehicle, or a second following control in which the host vehicle is automatically accelerated and decelerated so that the host vehicle speed, which is the traveling speed of the host vehicle, is maintained at a speed within a predetermined speed range, or the inter-vehicle distance is maintained at a distance within a predetermined distance range.

[0029] In the vehicle driving assistance method of the present invention, when a predetermined execution condition is met that indicates that a reduction in the amount of energy consumed by the drive device of the vehicle is requested, changes in the inter-vehicle distance and the vehicle speed when the first following control is executed are predicted, and the amount of energy consumed by the drive device of the vehicle when the first following control is executed is predicted as a first consumed energy amount based on the inter-vehicle distance and the vehicle speed when it is assumed that they have changed as predicted, and changes in the inter-vehicle distance and the vehicle speed when the second following control is executed are predicted, and the amount of energy consumed when the second following control is executed is predicted as a second consumed energy amount based on the inter-vehicle distance and the vehicle speed when it is assumed that they have changed as predicted, and if the second consumed energy amount is smaller than the first consumed energy amount, the second following control is executed, and if the second consumed energy amount is greater than or equal to the first consumed energy amount, the first following control is executed. In the vehicle driving assistance method according to the present invention, the second tracking control is a control that, when accelerating the host vehicle, accelerates the host vehicle by optimal acceleration control, which operates the drive device at an operating point where the amount of energy consumed by the drive device is minimum or approximately minimum, to accelerate the host vehicle, and, when decelerating the host vehicle, decelerates the host vehicle by coasting control, which causes the host vehicle to coast.

[0030] As described above, according to the present invention, the amount of energy consumed by the drive device can be reduced.

[0031] Furthermore, the present invention provides a vehicle driving assistance program for driving the host vehicle using a first following control that automatically controls the acceleration and deceleration of the host vehicle so that the vehicle-to-vehicle distance between the host vehicle and the preceding vehicle is maintained at a predetermined distance, thereby causing the host vehicle to follow the preceding vehicle, or a second following control that automatically accelerates and decelerates the host vehicle so that the host vehicle speed, which is the traveling speed of the host vehicle, is maintained at a speed within a predetermined speed range, or the vehicle-to-vehicle distance is maintained within a predetermined distance range.

[0032] The vehicle driving assistance program of the present invention, when a predetermined execution condition is met that a reduction in the amount of energy consumed by the drive device of the vehicle is requested, predicts changes in the inter-vehicle distance and the vehicle speed when the first follow-up control is executed, and predicts the amount of energy consumed by the drive device of the vehicle when the first follow-up control is executed as a first consumed energy amount based on the inter-vehicle distance and the vehicle speed when it is assumed that they have changed as predicted, and predicts changes in the inter-vehicle distance and the vehicle speed when the second follow-up control is executed, and predicts the amount of energy consumed when the second follow-up control is executed as a second consumed energy amount based on the inter-vehicle distance and the vehicle speed when it is assumed that they have changed as predicted, and executes the second follow-up control if the second consumed energy amount is smaller than the first consumed energy amount, and executes the first follow-up control if the second consumed energy amount is greater than or equal to the first consumed energy amount. In the vehicle driving assistance program of the present invention, the second following control is a control that, when accelerating the host vehicle, accelerates the host vehicle by optimal acceleration control, which operates the drive device at an operating point where the amount of energy consumed by the drive device is minimum or approximately minimum, to accelerate the host vehicle, and, when decelerating the host vehicle, decelerates the host vehicle by coasting control, which causes the host vehicle to coast.

[0033] As described above, according to the present invention, the amount of energy consumed by the drive device can be reduced.

[0034] 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 associated advantages of the present invention will be easily understood from the description of the embodiments of the present invention. [Brief description of the drawings]

[0035] [Figure 1]FIG. 1 is a diagram showing a vehicle driving support device according to an embodiment of the present invention and a vehicle (host vehicle) on which the vehicle driving support device is mounted. [Diagram 2] FIG. 2 is a diagram showing the distance between vehicles ahead. [Diagram 3] FIG. 3 is a diagram showing vehicles (neighboring vehicles) around the host vehicle. [Figure 4] FIG. 4 is a diagram showing the energy efficiency of an internal combustion engine, the energy efficiency of a motor, and the drive torque. [Diagram 5] FIG. 5 is a flowchart showing a routine executed by the vehicle driving assistance device according to the embodiment of the present invention. [Figure 6] FIG. 6 is a flowchart showing a routine executed by the vehicle driving assistance device according to the embodiment of the present invention. [Figure 7] FIG. 7 is a flowchart showing a routine executed by the vehicle driving assistance device according to the embodiment of the present invention. [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 diagram showing a map (lookup table) that defines the relationship between the inter-vehicle distance, the vehicle speed, and the amount of consumed energy. [Figure 16] FIG. 16 is a diagram showing the maximum allowable distance, the minimum allowable distance, and the allowable distance range RDpmt (second predetermined distance range). [Figure 17] FIG. 17 is a diagram for explaining a method of calculating the amount of energy consumed by the drive device (second amount of consumed energy) when the host vehicle is caused to travel under the asynchronous switching follow-up control. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0036] Hereinafter, a vehicle driving support device according to an embodiment of the present invention will be described with reference to the drawings. A vehicle driving support device 10 according to an embodiment of the present invention is shown in Fig. 1. The vehicle driving support device 10 is mounted on a host vehicle 100.

[0037] <ecu> The vehicle driving assistance device 10 includes an ECU 90 as a control device. ECU is an abbreviation for electronic control unit. The ECU 90 includes a microcomputer as a main part. The microcomputer includes a CPU, a ROM, a RAM, a non-volatile memory, and an interface. The CPU realizes various functions by executing instructions, programs, or routines stored in the ROM. In particular, the ROM stores a vehicle driving assistance program that executes the driving assistance control described later, and the CPU realizes the driving assistance control described later by executing the vehicle driving assistance program.

[0038] In particular, the ECU 90 pre-stores in ROM a program for executing the driving assistance control described below, but may be configured to wirelessly obtain and store such a program from a device external to the vehicle 100 via a receiving device, or to wirelessly update the stored program from a device external to the vehicle 100 via a receiving device.

[0039] <Vehicle driving device> The host vehicle 100 is equipped with a vehicle driving device 20. The vehicle driving device 20 is a device that drives, brakes, and steers the host vehicle 100, and in this example, includes a driving device 21, a braking device 22, and a steering device 23.

[0040] <Drive unit> The drive device 21 is a device that outputs a drive force (drive torque) given to the host vehicle 100 to make the host vehicle 100 travel, and in this example, is composed of two power sources (a first power source 211 and a second power source 212) having different power output characteristics. For example, the first power source 211 and the second power source 212 are an internal combustion engine and a motor, respectively. The first power source 211 and the second power source 212 are each electrically connected to the ECU 90. The ECU 90 can control the drive forces (drive torques) output from the first power source 211 and the second power source 212 by controlling the operation of the first power source 211 and the second power source 212, respectively.

[0041] <Brake device> The braking device 22 is a device that outputs a braking force (braking torque) applied to the host vehicle 100 in order to brake the host vehicle 100, and is, for example, a hydraulic brake device. The braking device 22 is electrically connected to the ECU 90. The ECU 90 can control the braking force (braking torque) output from the braking device 22 by controlling the operation of the braking device 22.

[0042] <Steering system> The steering device 23 is a device that outputs a steering force (steering torque) applied to the host vehicle 100 in order to steer the host vehicle 100, and is, for example, a power steering device. The steering device 23 is electrically connected to the ECU 90. The ECU 90 can control the steering force (steering torque) output from the steering device 23 by controlling the operation of the steering device 23.

[0043] <Sensors, etc.> Furthermore, the vehicle 100 is equipped with an accelerator pedal 41, an accelerator pedal operation amount sensor 42, a brake pedal 43, a brake pedal operation amount sensor 44, a steering wheel 45, a steering angle sensor 46, a steering torque sensor 47, a vehicle speed detection device 48, a driving assistance operation device 51, an efficiency-priority driving operation device 52, a surrounding information detection device 60, and a transmission / reception device 70.

[0044] <Accelerator pedal operation amount sensor> Accelerator pedal operation amount sensor 42 is a sensor that detects the amount of operation of accelerator pedal 41. Accelerator pedal operation amount sensor 42 is electrically connected to ECU 90. Accelerator pedal operation amount sensor 42 transmits information on the detected operation amount to ECU 90. ECU 90 obtains the operation amount of accelerator pedal 41 as accelerator pedal operation amount AP based on the information transmitted from accelerator pedal operation amount sensor 42.

[0045] Except when executing driving support control described later, the ECU 90 calculates and acquires a driving torque to be output from the drive device 21 based on the accelerator pedal operation amount AP and the driving speed of the host vehicle 100 (host vehicle speed V1), and sets the obtained torque as a driver requested driving torque TQ1drv_req. The ECU 90 causes the drive device 21 to output a driving torque equivalent to the driver requested driving torque TQ1drv_req. Furthermore, when executing driving support control described later, the ECU 90 sets a driving torque required for the host vehicle 100 to travel as desired by the driving support control as a system requested braking torque TQ2sys_req, and causes the drive device 21 to output a driving torque equivalent to the system requested braking torque TQ2sys_req.

[0046] <Brake pedal operation amount sensor> The brake pedal operation amount sensor 44 is a sensor that detects the amount of operation of the brake pedal 43. The brake pedal operation amount sensor 44 is electrically connected to the ECU 90. The brake pedal operation amount sensor 44 transmits information on the detected operation amount to the ECU 90. The ECU 90 obtains the operation amount of the brake pedal 43 as a brake pedal operation amount BP based on the information transmitted from the brake pedal operation amount sensor 44.

[0047] Except when executing driving support control described later, the ECU 90 calculates and obtains the braking torque to be applied to the host vehicle 100 by the brake device 22 based on the brake pedal operation amount BP, and sets the obtained braking torque as a driver requested braking torque TQ2drv_req. The ECU 90 applies a braking torque equivalent to the driver requested braking torque TQ2drv_req to the host vehicle 100 by the brake device 22. Furthermore, when executing driving support control described later, the ECU 90 sets a braking torque required for causing the host vehicle 100 to travel as desired by the driving support control as a system requested braking torque TQ2sys_req, and applies a braking torque equivalent to the system requested braking torque TQ2sys_req to the host vehicle 100 by the brake device 22.

[0048] <Steering angle sensor> The steering angle sensor 46 is a sensor that detects the rotation angle of the steering wheel 45 with respect to the neutral position. The steering angle sensor 46 is electrically connected to the ECU 90. The steering angle sensor 46 transmits information on the detected rotation angle of the steering wheel 45 to the ECU 90. The ECU 90 acquires the rotation angle of the steering wheel 45 as the steering angle θ based on the information.

[0049] <Steering torque sensor> The steering torque sensor 47 is a sensor that detects the torque input to the steering shaft by the driver of the host vehicle 100 (host vehicle driver) via the steering wheel 45. The steering torque sensor 47 is electrically connected to the ECU 90. The steering torque sensor 47 transmits information on the detected torque to the ECU 90. Based on the information, the ECU 90 obtains the torque input to the steering shaft by the host vehicle driver via the steering wheel 45 as a driver input steering torque TQ3drv.

[0050] <Vehicle speed detection device> The vehicle speed detection device 48 is a device that detects the traveling speed of the host vehicle 100, and is, for example, a wheel speed sensor. The vehicle speed detection device 48 is electrically connected to the ECU 90. The vehicle speed detection device 48 transmits information on the detected traveling speed of the host vehicle 100 to the ECU 90. The ECU 90 acquires the traveling speed of the host vehicle 100 as the host vehicle speed V1 based on the information.

[0051] The ECU 90 calculates the steering torque to be output from the steering device 23 based on the steering angle θ, the driver input steering torque TQ3drv, and the vehicle speed V1, sets it as a required steering torque TQ3req, and causes the steering device 23 to output a steering torque equivalent to the required steering torque TQ3req.

[0052] <Driving assistance control device> The driving support operation device 51 is a device operated by the driver of the vehicle, and is, for example, a device including switches, buttons, etc. These switches, buttons, etc. are provided, for example, on the steering wheel of the handlebars 45, or on a lever attached to the steering column of the vehicle 100.

[0053] In this example, the driving support operation device 51 includes a driving support 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 support operation device 51 is electrically connected to the ECU 90.

[0054] When the driving support selection switch is operated while driving support control, which will be described later, is not being executed, a signal is transmitted from the driving support operation device 51 to the ECU 90. When the ECU 90 receives the signal, it determines that execution of driving support control has been requested.

[0055] On the other hand, when the driving support selection switch is operated while driving support control is being executed, a signal is transmitted from the driving support operation device 51 to the ECU 90. When the ECU 90 receives the signal, it determines that the execution of the driving support control is no longer requested. In other words, the ECU 90 determines that the end of the driving support control has been requested.

[0056] Furthermore, when the vehicle speed setting switch is operated while the cruise assist control is being executed, a signal is transmitted from the cruise assist operation device 51 to the ECU 90. When the ECU 90 receives the signal, it sets the host vehicle speed V1 at that time as the set speed Vset for the cruise assist control.

[0057] Furthermore, when the vehicle speed increase button is operated while driving support control is being executed, a signal is sent from the driving support operation device 51 to the ECU 90. When the ECU 90 receives this signal, it increases the set speed Vset. On the other hand, when the vehicle speed decrease button is operated while driving support control is being executed, a signal is sent from the driving support operation device 51 to the ECU 90. When the ECU 90 receives this signal, it decreases the set speed Vset.

[0058] Furthermore, when the vehicle distance setting button is operated while driving support control is being executed, a signal is transmitted from the driving support operation device 51 to the ECU 90. This signal is a signal (required vehicle distance signal) that indicates a distance (required vehicle distance Dreq) that is requested as a distance (vehicle distance D) between the host vehicle 100 and the preceding vehicle 200F in normal following control, which will be described later, by the driver of the host vehicle operating the vehicle distance setting button.

[0059] As shown in Fig. 2, the inter-vehicle distance D is the distance between the host vehicle 100 and the preceding vehicle 200F, and is acquired based on the periphery detection information IS described later. In this example, the preceding vehicle 200F is a vehicle traveling ahead of the host vehicle 100 in the host vehicle lane LN (the lane in which the host vehicle 100 is traveling), and the inter-vehicle distance D is a predetermined distance (preceding vehicle determination distance Dth) or less. The host vehicle lane LN is recognized based on information related to the left-side marking line LML and the right-side marking line LMR of the host vehicle 100 acquired based on the periphery detection information IS. In this example, the requested inter-vehicle distance Dreq that can be selected by the host vehicle driver operating the inter-vehicle distance setting button is one of three types: a long distance Dlong, a medium distance Dmiddle, and a short distance Dshort.

[0060] When the ECU 90 receives a required inter-vehicle distance signal, it may set the set inter-vehicle distance Dset based on the required inter-vehicle distance Dreq regardless of the vehicle speed V1 at that time, but in this example, it sets the set inter-vehicle distance Dset based on the vehicle speed V1 and the required inter-vehicle distance Dreq at that time.

[0061] Specifically, the ECU 90 sets the inter-vehicle distance D, which is a predetermined time (predetermined predicted arrival time TTCref) obtained by dividing the time (predetermined predicted arrival time TTC) by the vehicle speed V1 at that time, as the set inter-vehicle distance Dset. That is, the ECU 90 sets the inter-vehicle distance D, which satisfies the relationship between the vehicle speed V1 at that time, the predetermined predicted arrival time TTCref, and the inter-vehicle distance D, as the set inter-vehicle distance Dset.

[0062] TTCref=D / V1 …(1)

[0063] The predetermined predicted arrival time TTCref is set to a longer time when the required inter-vehicle distance Dreq is a longer distance Dlong, set to a medium time when the required inter-vehicle distance Dreq is a medium distance Dmiddle, and set to a shorter time when the required inter-vehicle distance Dreq is a short distance Dshort. The preceding vehicle determination distance Dth is determined to be longer than the set inter-vehicle distance Dset.

[0064] <Efficiency-priority travel control device> The efficiency-priority traveling operation device 52 is a device operated by the driver of the vehicle, and is, for example, 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.

[0065] When the efficiency-priority-traveling operation device 52 is operated while in the OFF position, it is set to the ON position. When the efficiency-priority-traveling operation device 52 is operated to the ON position, it transmits a signal to the ECU 90. When the ECU 90 receives the signal, it determines that execution of efficiency-priority support control, which will be described later, has been requested.

[0066] On the other hand, when the efficiency priority traveling operation device 52 is operated while it is in the ON position, it is set to the OFF position. When the efficiency priority traveling operation device 52 is operated to the OFF position, it transmits a signal to the ECU 90. When the ECU 90 receives the signal, it determines that the execution of the efficiency priority support control is no longer required.

[0067] <Peripheral information detection device> The surrounding information detection device 60 is a device that detects information about the surroundings of the vehicle 100, and in this example, includes a radio wave sensor 61 and an image sensor 62.

[0068] <Radio wave sensor> The radio wave sensor 61 is a sensor that detects information about an object present in the vicinity of the vehicle 100 using radio waves, and is, for example, at least one of a radar sensor (such as a millimeter wave radar), a sonic sensor such as an ultrasonic sensor (clearance sonar), and an optical sensor such as a laser radar (LiDAR). The radio wave sensor 61 is electrically connected to the ECU 90. The radio wave sensor 61 transmits radio waves and receives radio waves (reflected waves) reflected by an object. The radio wave sensor 61 transmits information related to the transmitted radio waves and the received radio waves (reflected waves) to the ECU 90. In other words, the radio wave sensor 61 detects an object present in the vicinity of the vehicle 100 and transmits information related to the detected object to the ECU 90. The ECU 90 can obtain information related to an object present in the vicinity of the vehicle 100 as surrounding detection information IS based on the information (radio wave information or radio wave data). Objects detected using the radio wave sensor 61 are, for example, vehicles, walls, bicycles, people, and the like.

[0069] <Image sensor> The image sensor 62 is a sensor, such as a camera, that captures an image of the periphery of the vehicle 100. The image sensor 62 is electrically connected to the ECU 90. The image sensor 62 captures an image of the periphery of the vehicle 100 and transmits information related to the captured image to the ECU 90. The ECU 90 can acquire information about the periphery of the vehicle 100 as periphery detection information IS based on the information (image information or image data).

[0070] The ECU 90 acquires the distance between the preceding vehicle 200F and the host vehicle 100 (inter-vehicle distance D), the vehicle speed of the preceding vehicle 200F (preceding vehicle speed V2), and the like from the periphery detection information IS.

[0071] <Transmitter / receiver> The transmission / reception device 70 is a device that receives wireless signals transmitted from vehicles (nearby vehicles 200S) present in the vicinity of the vehicle 100 as shown in Fig. 3, and transmits wireless signals from the vehicle 100 to the outside, and is electrically connected to the ECU 90. The ECU 90 can acquire wireless signals transmitted from the nearby vehicles 200S via the transmission / reception device 70, and can transmit wireless signals from the vehicle 100 to the outside via the transmission / reception device 70. The ECU 90 acquires information related to the nearby vehicles 200S as inter-vehicle communication information IV based on the wireless signals transmitted from the nearby vehicles 200S.

[0072] <Operation of vehicle driving support device> Next, a description will be given of the operation of the vehicle driving support device 10. The vehicle driving support device 10 is configured to be capable of executing driving support control for automatically accelerating and decelerating the host vehicle 100 even without the driver of the host vehicle operating the accelerator pedal 41 or the brake pedal 43. In this example, the driving support control includes two types of control, that is, normal support control and efficiency priority support control.

[0073] <Normal support control> The normal support control includes two types of control, that is, normal following control (first following control) and normal constant speed control. In this example, the normal following control is a control that automatically accelerates and decelerates the host vehicle 100 so that the vehicle distance D is maintained at a set vehicle distance Dset (predetermined distance), but it may also be a control that automatically accelerates and decelerates the host vehicle 100 so that the distance is maintained within a predetermined range (first predetermined distance range) in which the upper limit value is a value larger than the set vehicle distance Dset by a predetermined value and the lower limit value is a value smaller than the set vehicle distance Dset by a predetermined value. On the other hand, the normal constant speed control is a control that automatically accelerates and decelerates the host vehicle 100 so that the host vehicle speed V1 is maintained at the set speed Vset.

[0074] <Efficiency Priority Support Control> Moreover, the efficiency priority support control is a control that automatically accelerates the host vehicle 100 by optimal acceleration control when accelerating the host vehicle 100, and automatically decelerates the host vehicle 100 by coasting control when decelerating the host vehicle 100. In this example, the efficiency priority support control includes three types of control, namely, synchronous operating point switching tracking control (synchronous switching tracking control, third tracking control), asynchronous operating point switching tracking control (asynchronous switching tracking control, second tracking control), and operating point switching constant speed control (switching constant speed control).

[0075] <Optimal acceleration control> The optimal acceleration control is a control in which a driving torque (optimal driving torque) at which the energy efficiency of the drive device 21 is maximized or nearly maximized when taking into account the vehicle speed at that time, in other words, a driving torque (optimal driving torque) at which the amount of energy consumed by the drive device 21 is minimized or nearly minimized, is obtained by calculation and set as the system required braking torque TQ2sys_req, and a driving torque equivalent to the system required braking torque TQ2sys_req is output from the drive device 21 to automatically accelerate the vehicle 100.

[0076] That is, in this example, the drive device 21 is composed of a first power source 211 and a second power source 212. Here, the first power source 211 and the second power source 212 have different power output characteristics (energy efficiency characteristics when outputting a driving force). In this example, the first power source 211 and the second power source 212 have the power output characteristics shown in Fig. 4. That is, as shown by the line Leng, the energy efficiency E of the first power source 211 is highest when the driving torque TQ1 output by the first power source 211 is a certain value TQ1_A, and the energy efficiency E of the second power source 212 is highest when the driving torque TQ1 output by the second power source 212 is a value TQ1_B smaller than the above value TQ1_A, as shown by the line Lmt.

[0077] When the first power source 211 is an internal combustion engine, the energy efficiency of the first power source 211 corresponds to so-called fuel efficiency, and increases as the fuel efficiency increases. On the other hand, when the second power source 212 is a motor, the energy efficiency of the second power source 212 corresponds to so-called electricity efficiency, and increases as the electricity efficiency decreases.

[0078] In this way, the energy efficiency of the drive device 21 has a characteristic that it peaks (is the largest) when the drive torque output by the drive device 21 is a specific value (optimum drive torque), and there are multiple peaks (two in this example). Therefore, if the optimum drive torque is output from the drive device 21 to accelerate the host vehicle 100, the energy efficiency of the drive device 21 increases. In other words, the amount of energy consumed by the drive device 21 decreases.

[0079] In this way, the optimal acceleration control is a control that causes the drive device 21 to output a drive torque equivalent to the optimal drive torque, thereby automatically accelerating the host vehicle 100. In other words, the optimal acceleration control is a control that causes the drive device 21 to operate with the minimum amount of energy consumption, thereby automatically accelerating the host vehicle 100.

[0080] The optimal acceleration control may be control in which a drive torque slightly larger or smaller than the optimal drive torque is obtained by calculation, set as a system required braking torque TQ2sys_req, and a drive torque equivalent to the system required braking torque TQ2sys_req is output from the drive device 21 to automatically accelerate the host vehicle 100. That is, the optimal acceleration control may be control in which the drive device 21 is operated with an optimal amount of consumed energy including "the minimum amount of consumed energy and an amount of consumed energy slightly larger than the minimum amount of consumed energy" to automatically accelerate the host vehicle 100. That is, the optimal acceleration control may be control in which the drive device 21 is operated so that the amount of consumed energy of the drive device 21 is equal to or less than a predetermined amount to automatically accelerate the host vehicle 100.

[0081] <Coasting control> On the other hand, the coasting control is a control for coasting the host vehicle 100 by outputting a driving torque from the drive device 21 that does not accelerate or decelerate the host vehicle 100. In this example, the coasting control is a control for coasting the host vehicle 100 by stopping the operation of the first power source 211 (e.g., an internal combustion engine) and outputting a driving torque from the second power source 212 (e.g., a motor) so that the energy efficiency of the second power source 212 is maximized. According to this, the host vehicle 100 is decelerated mainly due to its running resistance.

[0082] <Synchronous switching tracking control (third tracking control)> The synchronous switching following control is a control that automatically accelerates and decelerates the host vehicle 100 using optimal acceleration control and coasting control in synchronization (or approximately in synchronization) with the acceleration and deceleration of the preceding vehicle 200F, which is the synchronization target vehicle 200E, and is traveling using the same efficiency priority assist control (i.e., control that accelerates and decelerates the vehicle using optimal acceleration control and coasting control) as the efficiency priority assist control in this example.

[0083] The synchronization target vehicle 200E is a vehicle (peripheral vehicle 200S) surrounding the host vehicle 100, and is a vehicle equipped with a drive unit having the same or substantially the same power output characteristic as the drive unit 21 of the host vehicle 100.

[0084] In this example, information related to the control being executed on the drive unit of the nearby vehicle 200S is included in the inter-vehicle communication information IV, and therefore the vehicle driving assistance device 10 determines whether the nearby vehicle 200S is traveling under efficiency-priority assistance control based on the inter-vehicle communication information IV.

[0085] In addition, in this example, information related to the power output characteristics of the drive unit of the surrounding vehicle 200S is also included in the vehicle-to-vehicle communication information IV, and therefore, the vehicle driving assistance device 10 determines, based on the vehicle-to-vehicle communication information IV, whether or not the difference between the optimal drive torque of the drive unit of the surrounding vehicle 200S and the optimal drive torque of the drive unit 21 of the host vehicle 100 is less than a predetermined value (in this example, whether or not the power output characteristics of the drive unit of the surrounding vehicle 200S are the same or approximately the same as the power output characteristics of the drive unit 21 of the host vehicle 100).

[0086] In addition, information related to the control executed on the drive device of the nearby vehicle 200S may not be included in the inter-vehicle communication information IV. In this case, the vehicle driving support device 10 acquires the drive torque output from the drive device of the nearby vehicle 200S (the drive torque of the nearby vehicle 200S) based on the surrounding detection information IS, and determines whether the nearby vehicle 200S is traveling under the efficiency-priority support control based on the drive torque.

[0087] More specifically, the vehicle driving assistance device 10 acquires the peak value of the acceleration of the surrounding vehicle 200S (peak acceleration of the surrounding vehicle 200S) based on the surrounding detection information IS, and if the peak acceleration is consolidated into two specific values, it determines that the surrounding vehicle 200S is traveling using efficiency-priority assistance control.

[0088] Also, information related to the power output characteristics of the drive unit of the nearby vehicle 200S may not be included in the inter-vehicle communication information IV. In this case, the vehicle driving support device 10 acquires the drive torque of the nearby vehicle 200S based on the surrounding detection information IS, and determines whether or not the difference between the optimal drive torque of the nearby vehicle 200S and the optimal drive torque of the host vehicle 100 is equal to or less than a predetermined value based on the drive torque (i.e., whether or not the power output characteristics of the drive unit of the nearby vehicle 200S are the same or substantially the same as the power output characteristics of the drive unit 21 of the host vehicle 100).

[0089] More specifically, the vehicle driving assistance device 10 acquires the peak acceleration of the surrounding vehicle 200S based on the surrounding detection information IS, and if the difference between the peak acceleration and the peak value of the acceleration of the host vehicle 100 caused by the drive device 21 (peak acceleration of the host vehicle 100) is less than a predetermined value, it determines that the difference between the optimal drive torque of the drive device of the surrounding vehicle 200S and the optimal drive torque of the drive device 21 of the host vehicle 100 is less than a predetermined value (i.e., the power output characteristics of the drive device of the surrounding vehicle 200S are identical or approximately identical to the power output characteristics of the drive device 21 of the host vehicle 100).

[0090] In this example, the vehicle driving assistance device 10 obtains the peak acceleration of the surrounding vehicle 200S based on the surrounding detection information IS, and if the difference between the peak acceleration and the peak acceleration of the host vehicle 100 is zero, it determines that the power output characteristics of the drive unit of the surrounding vehicle 200S are identical to the power output characteristics of the drive unit 21 of the host vehicle 100, and if the difference between the peak acceleration of the surrounding vehicle 200S and the peak acceleration of the host vehicle 100 is greater than zero but less than a predetermined value, it determines that the power output characteristics of the drive unit of the surrounding vehicle 200S are approximately identical to the power output characteristics of the drive unit 21 of the host vehicle 100.

[0091] <Asynchronous switching tracking control (second tracking control)> Asynchronous switching following control is a control that automatically accelerates and decelerates the host vehicle 100 using optimal acceleration control and coasting control at a predetermined timing so as to follow a preceding vehicle 200F that is not a synchronized vehicle 200E, or a preceding vehicle 200F that is a synchronized vehicle 200E but is not traveling due to efficiency priority support control.

[0092] <Constant speed switching control> The switch constant speed control is a control for automatically accelerating and decelerating the host vehicle 100 by optimum acceleration control and coasting control at a predetermined timing so that the host vehicle speed is maintained within a predetermined range.

[0093] <Specific operation of the vehicle driving support device> Hereinafter, various controls including the normal assist control and the efficiency-priority assist control executed by the vehicle driving assist device 10 will be described in more detail with reference to the routines shown in FIGS.

[0094] The vehicle driving support device 10 executes the routine shown in Fig. 5 at a predetermined calculation cycle. Therefore, at a predetermined timing, the vehicle driving support device 10 starts the process from step 500 of the routine shown in Fig. 5, and advances the process to step 505.

[0095] When the driving support request condition C1 is satisfied, the vehicle driving support device 10 executes driving support control, and when the driving support request condition C1 is not satisfied, the vehicle driving support device 10 executes normal driving control. Therefore, when the vehicle driving support device 10 advances the process to step 505, it determines whether the driving support request condition C1 is satisfied.

[0096] The vehicle driving assistance device 10 may be configured to determine that the driving assistance request condition C1 is satisfied when the driving assistance operation device 51 is operated to request the execution of driving assistance control, regardless of whether the accelerator pedal 41 or the brake pedal 43 is operated. In this example, however, if it is determined that the execution of driving assistance control has been requested and neither the accelerator pedal 41 nor the brake pedal 43 is operated, the vehicle driving assistance device 10 determines that the driving assistance request condition C1 is satisfied.

[0097] In addition, when the driving support operation device 51 is operated during the execution of the driving support control to request the end of the driving support control, the vehicle driving support device 10 determines that the driving support request condition C1 is no longer satisfied, that is, the condition for terminating the driving support control (driving support end condition) is satisfied. In addition, when the brake pedal 43 is operated during the execution of the driving support control, that is, when the brake pedal operation amount BP becomes larger than zero, the vehicle driving support device 10 also determines that the driving support request condition C1 is no longer satisfied, that is, the driving support end condition is satisfied. When the driving support request condition C1 is no longer satisfied, the vehicle driving support device 10 ends the driving support control and executes normal driving control, which will be described later.

[0098] If the driving support request condition C1 is not satisfied, the vehicle driving support device 10 determines "No" in step 505 and proceeds to step 550 to execute normal driving control. After that, the vehicle driving support device 10 temporarily ends the processing of this routine.

[0099] Normal driving control is a control in which the driving torque to be output from the drive device 21 is calculated based on the accelerator pedal operation amount AP and the vehicle speed V1, and set as the driver requested driving torque TQ1drv_req, a driving torque equivalent to the driver requested driving torque TQ1drv_req is output from the drive device 21, the braking torque to be applied to the vehicle 100 by the braking device 22 is calculated based on the brake pedal operation amount BP, and set as the driver requested braking torque TQ2drv_req, and a braking torque equivalent to the driver requested braking torque TQ2drv_req is applied to the vehicle 100 by the braking device 22.

[0100] Furthermore, when normal driving control is being executed, the vehicle driving assistance device 10 is configured to, when the driver requested driving torque TQ1drv_req is greater than a value greater than zero (operation switchover threshold TQ1th), cause the driving device 21 to output a driving torque equivalent to the driver requested driving torque TQ1drv_req by outputting driving torque from both the first power source 211 and the second power source 212, and when the driver requested driving torque TQ1drv_req is equal to or less than the operation switchover threshold TQ1th, stop the operation of the first power source 211 and cause driving torque to be output only from the second power source 212, thereby outputting a driving torque equivalent to the driver requested driving torque TQ1drv_req from the driving device 21.

[0101] On the other hand, if the driving support request condition C1 is satisfied, the vehicle driving support device 10 judges “Yes” in step 505 and proceeds to step 510 .

[0102] The vehicle driving support device 10 executes efficiency-priority support control when the efficiency-priority requirement condition C2 is satisfied, and executes normal support control when the efficiency-priority requirement condition C2 is not satisfied. When the vehicle driving support device 10 advances the process to step 510, it determines whether the efficiency-priority requirement condition C2 is satisfied. When the efficiency-priority travel operation device 52 is operated to request the execution of efficiency-priority support control, the vehicle driving support device 10 determines that the efficiency-priority requirement condition C2 is satisfied.

[0103] If the efficiency priority requirement condition C2 is not satisfied, the vehicle driving assistance device 10 judges "No" in step 510, advances the process to step 545, and executes normal assistance control by executing the routine shown in Fig. 12. Therefore, when the vehicle driving assistance device 10 advances the process to step 545, it starts the process from step 1200 of the routine shown in Fig. 12, and advances the process to step 1205.

[0104] When the preceding vehicle 200F is present, the vehicle driving assistance device 10 executes normal following control as normal assistance control, and when the preceding vehicle 200F is not present, the vehicle driving assistance device 10 executes normal constant speed control as normal assistance control. Therefore, when the vehicle driving assistance device 10 advances the process to step 1205, it determines whether the preceding vehicle 200F is present.

[0105] If the preceding vehicle 200F is present, the vehicle driving assistance device 10 determines "Yes" in step 1205, advances the process to step 1210, and executes normal following control by executing the routine shown in Fig. 13. Therefore, when the vehicle driving assistance device 10 advances the process to step 1210, it starts the process from step 1300 of the routine shown in Fig. 13, and advances the process to step 1305.

[0106] As described above, the normal following control is a control that automatically accelerates and decelerates the host vehicle 100 so that the vehicle distance D is maintained at the set vehicle distance Dset. More specifically, in this example, the normal following control is a control that automatically accelerates and decelerates the host vehicle 100 so that the predicted arrival time TTC is maintained at the predetermined predicted arrival time TTCref. Therefore, the vehicle driving assistance device 10 accelerates the host vehicle 100 when the predicted arrival time TTC becomes longer than the predetermined predicted arrival time TTCref (when the normal following acceleration condition C3 is satisfied), and decelerates the host vehicle 100 when the predicted arrival time TTC becomes shorter than the predetermined predicted arrival time TTCref (when the normal following deceleration condition C4 is satisfied).

[0107] Therefore, the vehicle driving support device 10 determines whether or not the normal following acceleration condition C3 is satisfied when the process proceeds to step 1305. If the normal following acceleration condition C3 is satisfied, the vehicle driving support device 10 determines "Yes" in step 1305, proceeds to step 1310, and executes normal following acceleration control.

[0108] The normal following acceleration control is a control in which the driving torque to be output from the driving device 21 in order to converge the predicted arrival time TTC to a predetermined predicted arrival time TTCref is obtained by calculation and set as the system required braking torque TQ2sys_req, and a driving torque equivalent to that system required braking torque TQ2sys_req is output from the driving device 21.

[0109] After executing the process of step 1310, the vehicle driving assistance device 10 temporarily ends the process of this routine.

[0110] On the other hand, if the normal following acceleration condition C3 is not satisfied, the vehicle driving support device 10 judges "No" in step 1305 and proceeds to step 1315 to determine whether the normal following deceleration condition C4 is satisfied. If the normal following deceleration condition C4 is satisfied, the vehicle driving support device 10 judges "Yes" in step 1315 and proceeds to step 1320 to execute normal following deceleration control.

[0111] The normal following deceleration control is a control in which the driving torque to be output from the driving device 21 in order to converge the predicted arrival time TTC to a predetermined predicted arrival time TTCref is obtained by calculation and set as the system required braking torque TQ2sys_req, the braking torque to be applied to the host vehicle 100 by the braking device 22 is obtained by calculation and set as the system required braking torque TQ2sys_req, a driving torque equivalent to the system required braking torque TQ2sys_req is output from the driving device 21, and a braking torque equivalent to the system required braking torque TQ2sys_req is applied to the host vehicle 100 by the braking device 22.

[0112] After executing the process of step 1320, the vehicle driving assistance device 10 temporarily ends the process of this routine.

[0113] On the other hand, if the normal following deceleration condition C4 is not satisfied, the vehicle driving assistance device 10 determines "No" in step 1315, advances the process to step 1325, and executes steady driving control.

[0114] The steady running control is a control in which a drive torque for maintaining the vehicle speed at that time is obtained by calculation and set as a system required braking torque TQ2sys_req, and the system required braking torque TQ2sys_req is output from the drive device 21.

[0115] After executing the process of step 1325, the vehicle driving assistance device 10 temporarily ends the process of this routine.

[0116] If the accelerator pedal 41 is depressed during execution of the normal follow-up control and the driver requested driving torque TQ1drv_req becomes larger than the system requested braking torque TQ2sys_req, the vehicle driving assistance device 10 determines that an accelerator override state (driver override state) has occurred, interrupts the normal follow-up control, and causes the driving device 21 to output a driving torque equivalent to the driver requested driving torque TQ1drv_req. That is, the vehicle driving assistance device 10 interrupts the normal follow-up control and executes normal driving control. Thereafter, if the driver requested driving torque TQ1drv_req becomes equal to or smaller than the system requested braking torque TQ2sys_req due to, for example, the accelerator pedal 41 being released, the vehicle driving assistance device 10 resumes the normal follow-up control.

[0117] On the other hand, if the preceding vehicle 200F does not exist at the time of executing the processing of step 1205 of the routine shown in Fig. 12, the vehicle driving assistance device 10 determines "No" in step 1205, advances the processing to step 1215, and executes the routine shown in Fig. 14, thereby performing normal constant speed control. Therefore, when the vehicle driving assistance device 10 advances the processing to step 1215, the vehicle driving assistance device 10 starts the processing from step 1400 of the routine shown in Fig. 14, and advances the processing to step 1405.

[0118] As described above, the normal constant speed control is a control for automatically accelerating and decelerating the host vehicle 100 so that the host vehicle speed V1 is maintained at the set speed Vset. Therefore, the vehicle driving assistance device 10 accelerates the host vehicle 100 when the host vehicle speed V1 becomes lower than the set speed Vset (when the normal constant speed acceleration condition C5 is satisfied), and decelerates the host vehicle 100 when the host vehicle speed V1 becomes higher than the set speed Vset (when the normal constant speed deceleration condition C6 is satisfied).

[0119] Therefore, when the process proceeds to step 1405, the vehicle driving support device 10 determines whether or not the normal constant speed acceleration condition C5 is satisfied. If the normal constant speed acceleration condition C5 is satisfied, the vehicle driving support device 10 determines "Yes" in step 1405, proceeds to step 1410, and executes normal constant speed acceleration control.

[0120] Normal constant speed acceleration control is a control in which the driving torque that should be output from the drive device 21 in order to converge the vehicle speed V1 to the set speed Vset is obtained by calculation and set as the system required braking torque TQ2sys_req, and a driving torque equivalent to that system required braking torque TQ2sys_req is output from the drive device 21.

[0121] After executing the process of step 1410, the vehicle driving assistance device 10 temporarily ends the process of this routine.

[0122] On the other hand, if the normal constant speed acceleration condition C5 is not satisfied, the vehicle driving support device 10 judges "No" in step 1405 and proceeds to step 1415 to judge whether the normal constant speed deceleration condition C6 is satisfied. If the normal constant speed deceleration condition C6 is satisfied, the vehicle driving support device 10 judges "Yes" in step 1415 and proceeds to step 1420 to execute normal constant speed deceleration control.

[0123] Normal constant speed deceleration control is a control in which the driving torque to be output from the driving device 21 in order to converge the vehicle speed V1 to the set speed Vset is obtained by calculation and set as the system required braking torque TQ2sys_req, the braking torque to be applied to the vehicle 100 by the braking device 22 is obtained by calculation and set as the system required braking torque TQ2sys_req, a driving torque equivalent to the system required braking torque TQ2sys_req is output from the driving device 21, and a braking torque equivalent to the system required braking torque TQ2sys_req is applied to the vehicle 100 by the braking device 22.

[0124] After executing the process of step 1420, the vehicle driving assistance device 10 temporarily ends the process of this routine.

[0125] On the other hand, if the normal constant speed deceleration condition C6 is not satisfied, the vehicle driving support device 10 judges "No" in step 1415 and proceeds to step 1425 to execute the steady running control. After that, the vehicle driving support device 10 temporarily ends the processing of this routine.

[0126] Note that even during execution of the normal constant speed control, if the accelerator pedal 41 is depressed and the driver requested driving torque TQ1drv_req becomes larger than the system requested braking torque TQ2sys_req, the vehicle driving assistance device 10 determines that an accelerator override state has occurred, interrupts the normal constant speed control, and causes the driving device 21 to output a driving torque equivalent to the driver requested driving torque TQ1drv_req. That is, the vehicle driving assistance device 10 interrupts the normal constant speed control and executes normal driving control. Thereafter, if the driver requested driving torque TQ1drv_req becomes equal to or smaller than the system requested braking torque TQ2sys_req due to, for example, the accelerator pedal 41 being released, the vehicle driving assistance device 10 resumes the normal constant speed control.

[0127] On the other hand, if the efficiency-priority requirement condition C2 is satisfied at the time of executing the processing of step 510 of the routine shown in FIG. 5, the vehicle driving assistance device 10 judges “Yes” at step 510 and proceeds to step 515.

[0128] The vehicle driving assistance device 10 executes the synchronous switching follow-up control when the synchronization target vehicle 200E exists and is traveling under the efficiency-priority support control (i.e., when the synchronization condition is met), and executes the non-synchronous switching follow-up control or the switching constant speed control depending on whether the preceding vehicle 200F is present or not when the synchronization target vehicle 200E does not exist or when the synchronization target vehicle 200E exists but is not traveling under the efficiency-priority support control. Therefore, when the vehicle driving assistance device 10 advances the process to step 515, it determines whether the synchronization target vehicle 200E exists or not.

[0129] If the synchronization target vehicle 200E is present, the vehicle driving assistance device 10 judges "Yes" in step 515 and proceeds to step 520 to determine whether the synchronization target vehicle 200E is traveling under the efficiency-priority assist control. If the synchronization target vehicle 200E is traveling under the efficiency-priority assist control, the vehicle driving assistance device 10 judges "Yes" in step 520 and proceeds to step 525 to execute the routine shown in FIG. 6 or FIG. 7, thereby executing the synchronization switching follow-up control.

[0130] Therefore, in the case where the vehicle driving assistance device 10 is configured to execute the routine shown in FIG. 6 when the processing advances to step 525, when the processing advances to step 525, the vehicle driving assistance device 10 starts processing from step 600 of the routine shown in FIG. 6 and advances the processing to step 605.

[0131] When the synchronized vehicle 200E, which is traveling under efficiency-priority assist control, is the preceding vehicle 200F (when the control execution condition C7 is satisfied), the vehicle driving assistance device 10 executes acceleration / deceleration of the host vehicle 100 through optimal acceleration control and coasting control, but when the control execution condition C7 is not satisfied, the vehicle 100 is moved behind the synchronized vehicle 200E (other vehicle) and then acceleration / deceleration of the host vehicle 100 is executed through optimal acceleration control and coasting control.

[0132] Therefore, when the process proceeds to step 605, the vehicle driving assistance device 10 determines whether or not the control execution condition C7 is satisfied. If the control execution condition C7 is not satisfied, the vehicle driving assistance device 10 determines "No" in step 605, proceeds to step 630, and executes the host vehicle movement control. The host vehicle movement control is a control for moving the host vehicle 100 behind the synchronization target vehicle 200E. After executing the process of step 630, the vehicle driving assistance device 10 temporarily ends the process of this routine.

[0133] On the other hand, if the control execution condition C7 is satisfied, the vehicle driving assistance device 10 judges “Yes” in step 605 and proceeds to step 610.

[0134] In this example, the vehicle driving assistance device 10 is configured to move the host vehicle 100 behind the synchronized target vehicle 200E, which is traveling under efficiency-priority assistance control, by subject vehicle movement control if the synchronized target vehicle 200E is not the preceding vehicle 200F. Alternatively, the vehicle driving assistance device 10 may be configured to notify the host vehicle driver of the presence of the synchronized target vehicle 200E, which is traveling under efficiency-priority assistance control, by using a display, speaker, etc., or to suggest to the host vehicle driver by using a display, speaker, etc. that the host vehicle 100 should follow the synchronized target vehicle 200E.

[0135] As described above, the synchronization switching following control is a control for automatically accelerating and decelerating the host vehicle 100 by optimal acceleration control and coasting control in synchronization (or approximately in synchronization) with the acceleration and deceleration of the preceding vehicle 200F so as to follow the preceding vehicle 200F, which is a synchronization target vehicle 200E and is traveling under the efficiency priority support control. Therefore, when the preceding vehicle 200F is accelerating by the optimal acceleration control, the vehicle driving support device 10 accelerates the host vehicle 100 by the optimal acceleration control, and when the preceding vehicle 200F is decelerating due to the execution of the coasting control, the vehicle driving support device 10 decelerates the host vehicle 100 by the coasting control.

[0136] Therefore, when the process proceeds to step 610, the vehicle driving assistance device 10 determines whether or not there is information that the preceding vehicle 200F has accelerated, based on the vehicle-to-vehicle communication information IV. If there is information that the preceding vehicle 200F has accelerated, the vehicle driving assistance device 10 determines "Yes" in step 610, proceeds to step 615, and executes optimal acceleration control. Thereafter, the vehicle driving assistance device 10 temporarily ends the process of this routine.

[0137] On the other hand, if there is no information that the preceding vehicle 200F has accelerated, the vehicle driving assistance device 10 judges "No" in step 610 and proceeds to step 620 to determine whether there is information that the preceding vehicle 200F has decelerated based on the inter-vehicle communication information IV. If there is information that the preceding vehicle 200F has decelerated, the vehicle driving assistance device 10 judges "Yes" in step 620 and proceeds to step 625 to execute coasting control. Thereafter, the vehicle driving assistance device 10 temporarily ends the processing of this routine.

[0138] On the other hand, if there is no information that the preceding vehicle 200F has decelerated, the vehicle driving assistance device 10 judges "No" in step 620 and temporarily ends the processing of this routine. In this case, if the vehicle driving assistance device 10 is executing optimal acceleration control at that time, it continues the optimal acceleration control, and if the vehicle driving assistance device 10 is executing coasting control at that time, it continues the coasting control.

[0139] Alternatively, in the case where the vehicle driving assistance device 10 is configured to execute the routine shown in FIG. 7 when the processing proceeds to step 525, when the processing proceeds to step 525, the vehicle driving assistance device 10 starts processing from step 700 of the routine shown in FIG. 7, and proceeds to step 705 to determine whether or not the control execution condition C7 is satisfied.

[0140] If the control execution condition C7 is not satisfied, the vehicle driving assistance device 10 determines "No" in step 705 and proceeds to step 730 to execute the host vehicle movement control. After that, the vehicle driving assistance device 10 temporarily ends the processing of this routine.

[0141] On the other hand, if the control execution condition C7 is satisfied, the vehicle driving assistance device 10 judges "Yes" in step 705 and proceeds to step 710 to determine whether the preceding vehicle 200F has accelerated based on the surrounding detection information IS. If the preceding vehicle 200F has accelerated, the vehicle driving assistance device 10 judges "Yes" in step 710 and proceeds to step 715 to execute optimal acceleration control. Thereafter, the vehicle driving assistance device 10 temporarily ends the processing of this routine.

[0142] On the other hand, if the preceding vehicle 200F is not accelerating, the vehicle driving assistance device 10 judges "No" in step 710 and proceeds to step 720 to determine whether the preceding vehicle 200F has decelerated based on the surrounding detection information IS. If the preceding vehicle 200F has decelerated, the vehicle driving assistance device 10 judges "Yes" in step 720 and proceeds to step 725 to execute coasting control. Thereafter, the vehicle driving assistance device 10 temporarily ends the processing of this routine.

[0143] On the other hand, if the preceding vehicle 200F is not decelerating, the vehicle driving assistance device 10 determines "No" in step 720 and temporarily ends the processing of this routine. In this case, if the vehicle driving assistance device 10 is executing optimal acceleration control at that time, it continues the optimal acceleration control, and if the vehicle driving assistance device 10 is executing coasting control at that time, it continues the coasting control.

[0144] Incidentally, when the preceding vehicle 200F exists but is not the synchronization target vehicle 200E, or when the preceding vehicle 200F is the synchronization target vehicle 200E but is not traveling under the efficiency-priority support control, the vehicle driving support device 10 does not execute the synchronization switching follow-up control. At this time, there is also an option to execute the normal follow-up control, but since the normal follow-up control does not use the optimal acceleration control and coasting control for accelerating and decelerating the host vehicle 100, the energy efficiency of the drive device 21 for accelerating and decelerating the host vehicle 100 is lower than when accelerating and decelerating the host vehicle 100 using the optimal acceleration control and coasting control.

[0145] However, on the other hand, when the vehicle 100 is accelerated or decelerated using optimal acceleration control and coasting control, the inter-vehicle distance D increases or decreases, and therefore the effect of improving the energy efficiency of the drive unit 21 due to the reduction in the air resistance of the vehicle 100 (the effect of reducing air resistance) may be smaller than when normal following control is executed.

[0146] In this way, when comparing the case where the host vehicle 100 is driven using normal following control with the case where the host vehicle 100 is driven using optimal acceleration control and coasting control, when the host vehicle 100 is driven using normal following control, a certain amount of air resistance reduction effect is achieved, but the energy efficiency of the drive device 21 for accelerating and decelerating the host vehicle 100 is low, whereas when the host vehicle 100 is driven using optimal acceleration control and coasting control, the energy efficiency of the drive device 21 for accelerating and decelerating the host vehicle 100 is high, but the air resistance reduction effect may be small.

[0147] Therefore, when there is no synchronization target vehicle 200E, or when there is a synchronization target vehicle 200E but the synchronization target vehicle 200E is not traveling under efficiency-priority support control, the vehicle driving assistance device 10 determines whether to perform asynchronous switching follow-up control or normal follow-up control depending on whether there is a preceding vehicle 200F or not, and when there is no preceding vehicle 200F, performs switching constant speed control.

[0148] In other words, if the synchronization target vehicle 200E does not exist at the time of executing the processing of step 515 of the routine shown in Figure 5, the vehicle driving assistance device 10 judges "No" at step 515 and proceeds to the processing of step 530, where it determines whether or not a preceding vehicle 200F exists.

[0149] In addition, when the vehicle driving assistance device 10 executes the processing of step 520 of the routine shown in FIG. 5, if the synchronization target vehicle 200E is not traveling under efficiency-priority assistance control, the vehicle driving assistance device 10 judges "No" at step 520 and proceeds to the processing of step 530 to determine whether or not a preceding vehicle 200F is present.

[0150] If the preceding vehicle 200F is not present, the vehicle driving assistance device 10 determines "No" in step 530, advances the process to step 540, and executes the routine shown in Fig. 11 to perform switch constant speed control. Therefore, when the vehicle driving assistance device 10 advances the process to step 540, it starts the process from step 1100 of the routine shown in Fig. 11, and advances the process to step 1105.

[0151] As described above, the switch constant speed control is a control for accelerating and decelerating the host vehicle 100 by the optimal acceleration control and the coasting control at a predetermined timing so that the host vehicle speed V1 is maintained within a predetermined range. More specifically, in this example, the switch constant speed control is a control for automatically accelerating and decelerating the host vehicle 100 by the optimal acceleration control and the coasting control so that the host vehicle speed V1 is maintained within the set speed range RVset by setting a certain range with the set speed Vset as the median. Therefore, when the host vehicle speed becomes slower than the lower limit value of the set speed range RVset (when the switch constant speed acceleration condition C8 is satisfied), the vehicle driving assistance device 10 accelerates the host vehicle 100 by the optimal acceleration control, and when the host vehicle speed becomes faster than the upper limit value of the set speed range RVset (when the switch constant speed deceleration condition C9 is satisfied), the vehicle driving assistance device 10 decelerates the host vehicle 100 by the coasting control.

[0152] Therefore, when the process proceeds to step 1105, the vehicle driving support device 10 determines whether or not the switchover constant speed acceleration condition C8 is satisfied. If the switchover constant speed acceleration condition C8 is satisfied, the vehicle driving support device 10 determines "Yes" in step 1105 and proceeds to step 1110 to execute optimal acceleration control. After that, the vehicle driving support device 10 temporarily ends the process of this routine.

[0153] On the other hand, if the switchover constant speed acceleration condition C8 is not satisfied, the vehicle driving assistance device 10 judges "No" in step 1105 and proceeds to step 1115 to judge whether the switchover constant speed deceleration condition C9 is satisfied. If the switchover constant speed deceleration condition C9 is satisfied, the vehicle driving assistance device 10 judges "Yes" in step 1115 and proceeds to step 1120 to execute coasting control. Thereafter, the vehicle driving assistance device 10 temporarily ends the processing of this routine.

[0154] On the other hand, if the switching constant speed deceleration condition C9 is not satisfied, the vehicle driving assistance device 10 determines "No" in step 1115 and temporarily ends the processing of this routine. In this case, if the vehicle driving assistance device 10 is executing the optimal acceleration control at that time, it continues the optimal acceleration control, and if the vehicle driving assistance device 10 is executing the coasting control at that time, it continues the coasting control.

[0155] On the other hand, when the vehicle driving assistance device 10 determines that the preceding vehicle 200F exists at the time of executing the process of step 530 of the routine shown in Fig. 5 as "Yes", advances the process to step 535, and executes the routine shown in Fig. 8. Therefore, when the vehicle driving assistance device 10 advances the process to step 535, it starts the process from step 800 of the routine shown in Fig. 8.

[0156] The vehicle driving assistance device 10 executes asynchronous switching following control when the amount of energy consumed by the drive device 21 is less when the vehicle 100 is driven by asynchronous switching following control than when the vehicle 100 is driven by normal following control, and executes normal following control when the amount of energy consumed by the drive device 21 is greater when the vehicle 100 is driven by asynchronous switching following control than when the vehicle 100 is driven by normal following control.

[0157] Therefore, the vehicle driving assistance device 10 obtains the amount of energy consumed by the drive device 21 when the vehicle 100 is driven by normal tracking control (first consumed energy amount EN1) and the amount of energy consumed by the drive device 21 when the vehicle 100 is driven by asynchronous switching tracking control (second consumed energy amount EN2) as follows.

[0158] That is, the amount of energy consumed by the drive device 21 that is reduced by the reduction in air resistance of the host vehicle 100 as a result of the host vehicle 100 traveling following the preceding vehicle 200F (follow-up driving reduction amount ΔENacc) varies depending on the type of the preceding vehicle 200F (particularly, the body size of the preceding vehicle 200F). In general, the larger the body of the preceding vehicle 200F is, the smaller the air resistance of the host vehicle 100 becomes. Therefore, the vehicle driving assistance device 10 acquires the type of the preceding vehicle 200F based on the surrounding detection information IS and / or the vehicle-to-vehicle communication information IV.

[0159] The following driving reduction amount ΔENacc also varies depending on the inter-vehicle distance D and the host vehicle speed V1. In general, the shorter the inter-vehicle distance D, the smaller the air resistance of the host vehicle 100, and the lower the host vehicle speed V1, the smaller the air resistance of the host vehicle 100. Therefore, the vehicle driving assistance device 10 predicts the future preceding vehicle speed V2 based on the change history of the preceding vehicle speed V2 acquired and stored based on the surrounding detection information IS and / or the inter-vehicle communication information IV, and predicts the inter-vehicle distance D and the host vehicle speed V1 when the host vehicle 100 is caused to follow the preceding vehicle 200F traveling at the predicted preceding vehicle speed V2 (predicted preceding vehicle speed V2pre) by normal following control.

[0160] Then, the vehicle driving assistance device 10 calculates the amount of energy consumed by the drive device 21 when the vehicle 100 is driven by normal following control based on the type of the preceding vehicle 200F and the predicted inter-vehicle distance D and vehicle speed V1, and sets this amount of energy consumption as the first consumed energy amount EN1.

[0161] In this example, the vehicle driving assistance device 10 pre-stores a map (lookup table) for obtaining the amount of energy consumed by the drive unit 21 from the vehicle distance D and the vehicle speed V1 for each type of preceding vehicle 200F, as shown in Figure 15. Therefore, when obtaining the amount of energy consumed by the drive unit 21 when the vehicle 100 is driven by normal following control, the map corresponding to the type of preceding vehicle 200F is selected, and the amount of energy consumed is obtained by applying the predicted vehicle distance D and vehicle speed V1 as described above to the map, thereby obtaining the amount of energy consumed by the drive unit 21 when the vehicle 100 is driven by normal following control.

[0162] On the other hand, when the host vehicle 100 is caused to run by the asynchronous switching following control, the vehicle distance D increases or decreases significantly and the host vehicle speed V1 increases or decreases significantly compared to when the host vehicle 100 is caused to run by the normal following control, but if the vehicle distance D becomes excessively large or the host vehicle speed V1 becomes excessively small, this may cause traffic congestion, which is undesirable. Therefore, when the host vehicle 100 is caused to run by the asynchronous switching following control, it is preferable to run the host vehicle 100 by the asynchronous switching following control so that the vehicle distance D does not become larger than the maximum allowable distance (maximum allowable distance Dmax) and the host vehicle speed V1 does not become smaller than the minimum allowable speed (minimum allowable speed Vmin).

[0163] Furthermore, from the viewpoint of ensuring the traveling safety of the host vehicle 100, it is undesirable that the inter-vehicle distance D becomes excessively small or the host vehicle speed V1 becomes excessively large. Furthermore, the host vehicle speed V1 should be limited to a range not exceeding the speed limit set by traffic regulations. Therefore, when the host vehicle 100 is caused to travel by the asynchronous switching following control, it is preferable to cause the host vehicle 100 to travel by the asynchronous switching following control so that the inter-vehicle distance D is not smaller than the minimum allowable distance (minimum allowable distance Dmin) and the host vehicle speed V1 is not larger than the maximum allowable speed (maximum allowable speed Vmax).

[0164] Based on the above, the vehicle driving assistance device 10 sets a maximum allowable distance Dmax and a minimum allowable distance Dmin, as shown in Figure 16, and sets the range between the maximum allowable distance Dmax and the minimum allowable distance Dmin as the allowable distance range RDpmt (second specified distance range), and sets a maximum allowable speed Vmax and a minimum allowable speed Vmin, and sets the range between the maximum allowable speed Vmax and the minimum allowable speed Vmin as the allowable speed range RVpmt (specified speed range).

[0165] As mentioned above, when the normal tracking control is a control that automatically accelerates and decelerates the vehicle 100 so as to maintain the distance within a predetermined range (first predetermined distance range), the allowable distance range RDpmt (second predetermined distance range) is set to a range wider than the predetermined range (first predetermined distance range) in the normal tracking control.

[0166] In addition, the maximum allowable distance Dmax is generally smaller on a general road than on an expressway, and the minimum allowable speed Vmin is generally smaller on a general road than on an expressway. It is preferable that the allowable distance range RDpmt and the allowable speed range RVpmt are set according to the driving environment, such as the type of road on which the vehicle 100 is traveling. Therefore, in this example, the vehicle driving assistance device 10 sets the maximum allowable distance Dmax, the minimum allowable distance Dmin, the maximum allowable speed Vmax, and the minimum allowable speed Vmin according to the driving environment of the vehicle 100, and sets the allowable distance range RDpmt and the allowable speed range RVpmt. In addition, the maximum allowable distance Dmax may be set to a distance according to the driving environment of the vehicle 100 and the required inter-vehicle distance Dreq. In this case, the longer the required inter-vehicle distance Dreq, the longer the maximum allowable distance Dmax is set to.

[0167] Then, subject to satisfying the constraints of maintaining the inter-vehicle distance D within the permissible distance range RDpmt and maintaining the host vehicle speed V1 at a speed within the permissible speed range RVpmt, the vehicle driving assistance device 10 acquires the acceleration start speed Vacc (threshold value of the host vehicle speed V1 at which optimal acceleration control is started), acceleration start distance Dacc (threshold value of the inter-vehicle distance D at which optimal acceleration control is started), coasting start speed Vcst (threshold value of the host vehicle speed V1 at which coasting control is started), and coasting start distance Dcst (threshold value of the inter-vehicle distance D at which coasting control is started) that minimize the amount of energy consumed by the drive unit 21 when the host vehicle 100 is caused to travel using asynchronous switching following control against the preceding vehicle 200F traveling at the predicted preceding vehicle speed V2 (predicted preceding vehicle speed V2pre) as described above, and acquires the amount of energy consumed at that time, and sets the amount of consumed energy as the second consumed energy amount EN2.

[0168] At this time, the vehicle driving assistance device 10 predicts the inter-vehicle distance D and the host vehicle speed V1 when the host vehicle 100 is caused to travel following the preceding vehicle 200F by the asynchronous switching following control, applies the inter-vehicle distance D and the host vehicle speed V1 to a map (see FIG. 15) corresponding to the type of the preceding vehicle 200F to obtain the amount of consumed energy, sets the amount of consumed energy as the basic amount of consumed energy ENbase (see FIG. 17), and further calculates the difference in the amount of consumed energy when the host vehicle 100 is accelerated by the optimal acceleration control relative to the amount of consumed energy when the host vehicle 100 is accelerated by the following travel control (optimal acceleration reduction amount Δ ENopt), and if energy is consumed when switching from coasting control to optimal acceleration control, the amount of consumed energy (operating point switching increase amount ΔENsw) is obtained. The optimal acceleration reduction amount ΔENopt is subtracted from the basic energy consumption amount ENbase (see Figure 17), and the operating point switching increase amount ΔENsw is added to this (see Figure 17) to obtain the amount of energy consumed by the drive device 21 when the vehicle 100 is driven using asynchronous switching tracking control (i.e., the second consumed energy amount EN2) (EN2=ENbase-ΔENopt+ΔENsw).

[0169] In addition, when the acquired acceleration start speed Vacc is greater than the minimum allowable speed Vmin, the acceleration start speed Vacc is the optimal speed for reducing the amount of consumed energy (optimum acceleration start speed Vacc_opt), and when the acquired coasting start speed Vcst is less than the maximum allowable speed Vmax, the coasting start speed Vcst is the optimal speed for reducing the amount of consumed energy (optimum coasting start speed Vcst_opt). Similarly, when the acquired acceleration start distance Dacc is less than the maximum allowable distance Dmax, the acceleration start distance Dacc is the optimal distance for reducing the amount of consumed energy (optimum acceleration start distance Dacc_opt), and when the acquired coasting start distance Dcst is greater than the minimum allowable distance Dmin, the coasting start distance Dcst is the optimal distance for reducing the amount of consumed energy (optimum coasting start distance Dcst_opt).

[0170] Then, the vehicle driving assistance device 10 compares the second consumed energy amount EN2 with the first consumed energy amount EN1, and if the second consumed energy amount EN2 is smaller than the first consumed energy amount EN1, executes asynchronous switching tracking control, and if the second consumed energy amount EN2 is greater than or equal to the first consumed energy amount EN1, executes normal tracking control.

[0171] In addition, when the vehicle driving assistance device 10 executes the asynchronous switching follow-up control, if the optimal switching permission condition C10 is satisfied, the vehicle driving assistance device 10 executes the asynchronous switching follow-up control (optimum switching follow-up control) using the optimal acceleration start speed Vacc_opt, the optimal coasting start speed Vcst_opt, the optimal acceleration start distance Dacc_opt, and the optimal coasting start distance Dcst_opt. In this example, the optimal switching permission condition C10 is a condition that (1) the acceleration start distance Dacc acquired as described above is smaller than the maximum allowable distance Dmax, (2) the coasting start distance Dcst acquired as described above is larger than the minimum allowable distance Dmin, (3) the acceleration start speed Vacc acquired as described above is larger than the minimum allowable speed Vmin, and (4) the coasting start speed Vcst acquired as described above is smaller than the maximum allowable speed Vmax.

[0172] In this case, specifically, the vehicle driving assistance device 10 starts coasting control when the host vehicle speed V1 increases and reaches the optimal coasting start speed Vcst_opt, or starts coasting control when the vehicle distance D decreases and reaches the optimal coasting start distance Dcst_opt, starts optimal acceleration control when the host vehicle speed V1 decreases and reaches the optimal acceleration start speed Vacc_opt, and starts optimal acceleration control when the vehicle distance D increases and reaches the optimal acceleration start distance Dacc_opt. That is, the vehicle driving assistance device 10 automatically accelerates and decelerates the host vehicle 100 so that the host vehicle speed V1 is maintained at a speed within a predetermined speed range determined by the optimal coasting start speed Vcst_opt and the optimal acceleration start speed Vacc_opt, or so that the vehicle distance D is maintained at a distance within a predetermined distance range (second predetermined distance range) determined by the optimal coasting start speed Dcst_opt and the optimal acceleration start distance Dacc_opt, and makes the host vehicle 100 travel following the preceding vehicle 200F. The predetermined distance range (second predetermined distance range) determined by the optimal coasting start distance Dcst_opt and the optimal acceleration start distance Dacc_opt is set to a range wider than the predetermined range (first predetermined distance range) in the normal tracking control.

[0173] On the other hand, when the optimal switching permission condition C10 is not satisfied, the vehicle driving assistance device 10 executes asynchronous switching follow-up control (limited switching follow-up control) using the minimum permissible speed Vmin, the maximum permissible distance Dmax, and the maximum permissible speed Vmax and the minimum permissible distance Dmin.

[0174] In this case, specifically, the vehicle driving assistance device 10 starts coasting control when the host vehicle speed V1 increases and reaches the maximum permissible speed Vmax, or starts coasting control when the vehicle distance D decreases and reaches the minimum permissible distance Dmin, and starts optimal acceleration control when the host vehicle speed V1 decreases and reaches the minimum permissible speed Vmin, or starts optimal acceleration control when the vehicle distance D increases and reaches the maximum permissible distance Dmax. That is, the vehicle driving assistance device 10 automatically accelerates and decelerates the host vehicle 100 so that the host vehicle speed V1 is maintained at a speed within a predetermined speed range determined by the maximum permissible speed Vmax and the minimum permissible speed Vmin, or so that the vehicle distance D is maintained at a distance within a predetermined distance range determined by the minimum permissible distance Dmin and the maximum permissible distance Dmax, and makes the host vehicle 100 travel following the preceding vehicle 200F.

[0175] Therefore, when the vehicle driving assistance device 10 starts processing from step 800 of the routine shown in FIG. 8, it proceeds to step 805, obtains the type of the preceding vehicle 200F (in particular, the size of the preceding vehicle 200F), and predicts the future preceding vehicle speed V2.

[0176] Next, the vehicle driving assistance device 10 advances the process to step 810 and selects a map (lookup table) corresponding to the acquired type of the preceding vehicle 200F. Next, the vehicle driving assistance device 10 advances the process to step 815 and acquires the first consumed energy amount EN1 as described above using the map selected in step 810. Next, the vehicle driving assistance device 10 advances the process to step 820 and sets the permissible distance range RDpmt and the permissible speed range RVpmt.

[0177] Next, the vehicle driving assistance device 10 advances the process to step 825 and acquires the acceleration start speed Vacc, the coasting start speed Vcst, the acceleration start distance Dacc, and the coasting start distance Dcst. Next, the vehicle driving assistance device 10 advances the process to step 830 and acquires the second consumed energy amount EN2 as described above using the map selected in step 810.

[0178] Next, the vehicle driving support device 10 proceeds to step 835 to determine whether the second consumed energy amount EN2 is smaller than the first consumed energy amount EN1. If the second consumed energy amount EN2 is smaller than the first consumed energy amount EN1, the vehicle driving support device 10 determines "Yes" in step 835 and proceeds to step 840 to determine whether the optimal switching permission condition C10 is satisfied.

[0179] If the optimal switching permission condition C10 is satisfied, the vehicle driving assistance device 10 judges "Yes" in step 840, advances the process to step 845, and executes the routine shown in FIG. 9 to perform optimal switching follow-up control.

[0180] 9, and then proceeds to step 905 to determine whether the optimal switchover follow-up acceleration condition C11 is satisfied. In this example, the vehicle driving assistance device 10 determines whether the host vehicle speed V1 is smaller than the optimal acceleration start speed Vacc_opt or whether the inter-vehicle distance D is larger than the optimal acceleration start distance Dacc_opt.

[0181] If the optimal switchover following acceleration condition C11 is satisfied, the vehicle driving support device 10 judges "Yes" in step 905 and proceeds to step 910 to execute optimal acceleration control. After that, the vehicle driving support device 10 temporarily ends the processing of this routine.

[0182] On the other hand, if the optimal switching follow-up acceleration condition C11 is not satisfied, the vehicle driving assistance device 10 judges "No" in step 905 and proceeds to step 915 to judge whether the optimal switching follow-up deceleration condition C12 is satisfied. In this example, as this judgment, the vehicle driving assistance device 10 judges whether the host vehicle speed V1 is greater than the optimal coasting start speed Vcst_opt or whether the inter-vehicle distance D is smaller than the optimal coasting start distance Dcst_opt.

[0183] If the optimal switchover following deceleration condition C12 is satisfied, the vehicle driving support device 10 judges "Yes" in step 915 and proceeds to step 920 to execute coasting control. After that, the vehicle driving support device 10 temporarily ends the processing of this routine.

[0184] On the other hand, if the optimal switch following deceleration condition C12 is not satisfied, the vehicle driving assistance device 10 judges "No" in step 915 and temporarily ends the processing of this routine. In this case, if the vehicle driving assistance device 10 is executing the optimal acceleration control at that time, it continues the optimal acceleration control, and if the vehicle driving assistance device 10 is executing the coasting control at that time, it continues the coasting control.

[0185] In addition, when the optimal switching permission condition C10 is not satisfied at the time of executing the processing of step 840 of the routine shown in FIG. 8, the vehicle driving assistance device 10 judges “No” at step 840, advances the processing to step 850, and executes the routine shown in FIG. 10 to perform limited switching follow-up control.

[0186] Therefore, when the vehicle driving assistance device 10 advances the process to step 850, it starts the process from step 1000 of the routine shown in Fig. 10, advances the process to step 1005, and determines whether or not the limit switching following acceleration condition C13 is satisfied. In this example, as this determination, the vehicle driving assistance device 10 determines whether or not the host vehicle speed V1 is smaller than the minimum permissible speed Vmin, or whether or not the inter-vehicle distance D is larger than the maximum permissible distance Dmax.

[0187] If the limit switching following acceleration condition C13 is satisfied, the vehicle driving support device 10 judges "Yes" in step 1005 and proceeds to step 1010 to execute optimal acceleration control. After that, the vehicle driving support device 10 temporarily ends the processing of this routine.

[0188] On the other hand, if the limit switching following acceleration condition C13 is not satisfied, the vehicle driving support device 10 judges "No" in step 1005 and proceeds to step 1015 to judge whether the limit switching following deceleration condition C14 is satisfied. In this example, as this judgment, the vehicle driving support device 10 judges whether the host vehicle speed V1 is greater than the maximum permissible speed Vmax or whether the inter-vehicle distance D is shorter than the minimum permissible distance Dmin.

[0189] If the limit switching following deceleration condition C14 is satisfied, the vehicle driving support device 10 judges "Yes" in step 1015 and proceeds to step 1020 to execute coasting control. After that, the vehicle driving support device 10 temporarily ends the processing of this routine.

[0190] On the other hand, if the limit switching following deceleration condition C14 is not satisfied, the vehicle driving assistance device 10 determines "No" in step 1015 and temporarily ends the processing of this routine.

[0191] Furthermore, when the second consumed energy amount EN2 is equal to or greater than the first consumed energy amount EN1 at the time of executing the process of step 835 of the routine shown in Fig. 8, the vehicle driving assistance device 10 judges "No" in that step 835 and advances the process to step 855, and executes the normal tracking control by executing the routine shown in Fig. 13 as described above. After that, the vehicle driving assistance device 10 temporarily ends the process of this routine.

[0192] The above is the operation of the vehicle driving assistance device 10. According to the vehicle driving assistance device 10, even when the host vehicle 100 cannot be driven by the synchronous switching tracking control, the host vehicle 100 may be driven by the asynchronous switching tracking control, so that the energy efficiency of the drive device 21 can be improved.

[0193] The present invention is not limited to the above-described embodiment, and various modifications can be made within the scope of the present invention.

[0194] For example, the above-mentioned vehicle driving assistance device 10 adopts the condition that the driving assistance request condition C1 and the efficiency priority request condition C2 are satisfied as the condition (predetermined execution condition) for executing asynchronous switching tracking control, but it is also possible to omit the efficiency priority request condition C2 being satisfied and adopt only the condition that the driving assistance request condition C1 is satisfied. [Explanation of symbols]

[0195] 10...vehicle driving assistance device, 20...vehicle driving device, 21...driving device, 48...vehicle speed detection device, 51...driving assistance operation device, 52...efficiency priority driving operation device, 60...peripheral information detection device, 70...transmitter / receiver device, 90...ECU, 100...own vehicle, 200F...preceding vehicle, 200S...peripheral vehicle< / ecu>

Claims

1. A vehicle driving assistance device including a control device that executes a first following control for automatically controlling acceleration / deceleration of the host vehicle so that the vehicle distance between the host vehicle and a preceding vehicle is maintained within a first predetermined distance range, thereby causing the host vehicle to travel following the preceding vehicle, and a second following control for automatically accelerating / decelerating the host vehicle so that the host vehicle speed, which is the traveling speed of the host vehicle, is maintained at a speed within a predetermined speed range or so that the vehicle distance is maintained within a second predetermined distance range that is wider than the first predetermined distance range, The control device includes: predicting an amount of energy consumed by a drive device of the host vehicle when the first follow-up control is executed as a first consumed energy amount, and predicting the amount of energy consumed when the second follow-up control is executed as a second consumed energy amount; When the second consumed energy amount is smaller than the first consumed energy amount, the second tracking control is executed; When the second consumed energy amount is equal to or greater than the first consumed energy amount, the first tracking control is executed. It is configured as follows: In a vehicle driving assistance device, The second tracking control is a control for accelerating the host vehicle by optimal acceleration control, which operates the drive device at an operating point where an amount of energy consumption of the drive device is minimum or approximately minimum, to accelerate the host vehicle, when accelerating the host vehicle, and for decelerating the host vehicle by coasting control, which causes the host vehicle to coast. Vehicle driving assistance device.

2. A vehicle driving assistance device including a control device that executes a first following control for automatically controlling acceleration / deceleration of the host vehicle so that the vehicle distance between the host vehicle and a preceding vehicle is maintained within a first predetermined distance range, thereby causing the host vehicle to travel following the preceding vehicle, and a second following control for automatically accelerating / decelerating the host vehicle so that the host vehicle speed, which is the traveling speed of the host vehicle, is maintained at a speed within a predetermined speed range or so that the vehicle distance is maintained within a second predetermined distance range that is wider than the first predetermined distance range, The control device includes: predicting an amount of energy consumed by a drive device of the host vehicle when the first follow-up control is executed as a first consumed energy amount, and predicting the amount of energy consumed when the second follow-up control is executed as a second consumed energy amount; When the second consumed energy amount is smaller than the first consumed energy amount, the second tracking control is executed; When the second consumed energy amount is equal to or greater than the first consumed energy amount, the first tracking control is executed. It is configured as follows: In a vehicle driving assistance device, the control device is configured to execute a third following control for causing the host vehicle to run following the preceding vehicle by accelerating or decelerating the host vehicle in synchronization or approximately synchronization with the acceleration and deceleration of the preceding vehicle, and when accelerating the host vehicle, to accelerate the host vehicle by optimal acceleration control that operates the drive device of the host vehicle at an operating point where the amount of energy consumed by the drive device is minimum or approximately minimum to accelerate the host vehicle, and when decelerating the host vehicle, to execute a third following control that decelerates the host vehicle by coasting control that coasts the host vehicle; The control device includes: when a predetermined execution condition is satisfied that a reduction in the amount of energy consumed by the drive device of the host vehicle is requested, if a synchronization condition is satisfied that the power output characteristics of the drive device of the preceding vehicle are the same or substantially the same as the power output characteristics of the drive device of the host vehicle and the preceding vehicle is traveling under the same control as the second follow-up control or the third follow-up control, execute the third follow-up control; When the predetermined execution condition is satisfied, if the synchronization condition is not satisfied, the first follow-up control or the second follow-up control is executed. It is configured as follows: Vehicle driving assistance device.

3. A vehicle driving assistance device including a control device that executes a first following control for automatically controlling acceleration / deceleration of the host vehicle so that the vehicle distance between the host vehicle and a preceding vehicle is maintained within a first predetermined distance range, thereby causing the host vehicle to travel following the preceding vehicle, and a second following control for automatically accelerating / decelerating the host vehicle so that the host vehicle speed, which is the traveling speed of the host vehicle, is maintained at a speed within a predetermined speed range or so that the vehicle distance is maintained within a second predetermined distance range that is wider than the first predetermined distance range, The control device includes: predicting an amount of energy consumed by a drive device of the host vehicle when the first follow-up control is executed as a first consumed energy amount, and predicting the amount of energy consumed when the second follow-up control is executed as a second consumed energy amount; When the second consumed energy amount is smaller than the first consumed energy amount, the second tracking control is executed; When the second consumed energy amount is equal to or greater than the first consumed energy amount, the first tracking control is executed. It is configured as follows: In a vehicle driving assistance device, the control device is configured to execute a third following control for causing the host vehicle to run following the preceding vehicle by accelerating or decelerating the host vehicle in synchronization or approximately synchronization with the acceleration and deceleration of the preceding vehicle, and when accelerating the host vehicle, to accelerate the host vehicle by optimal acceleration control that operates the drive device of the host vehicle at an operating point where the amount of energy consumed by the drive device is minimum or approximately minimum to accelerate the host vehicle, and when decelerating the host vehicle, to execute a third following control that decelerates the host vehicle by coasting control that coasts the host vehicle; The control device is configured to detect another vehicle equipped with a drive device having a power output characteristic that is the same or substantially the same as the power output characteristic of the drive device of the host vehicle, and to move the host vehicle behind the other vehicle and execute the third following control when the other vehicle is traveling under the same control as the second following control or the third following control. Vehicle driving assistance device.

4. The vehicle driving support device according to any one of claims 1 to 3, The control device is configured to take into account a size of the preceding vehicle when predicting the first consumed energy amount and the second consumed energy amount. Vehicle driving assistance device.

5. A vehicle driving assistance device including a control device that executes a first following control for automatically controlling acceleration / deceleration of the host vehicle so that the vehicle distance between the host vehicle and a preceding vehicle is maintained within a first predetermined distance range, thereby causing the host vehicle to travel following the preceding vehicle, and a second following control for automatically accelerating / decelerating the host vehicle so that the host vehicle speed, which is the traveling speed of the host vehicle, is maintained at a speed within a predetermined speed range or so that the vehicle distance is maintained within a second predetermined distance range that is wider than the first predetermined distance range, The control device includes: predicting an amount of energy consumed by a drive device of the host vehicle when the first follow-up control is executed as a first consumed energy amount, and predicting the amount of energy consumed when the second follow-up control is executed as a second consumed energy amount; When the second consumed energy amount is smaller than the first consumed energy amount, the second tracking control is executed; When the second consumed energy amount is equal to or greater than the first consumed energy amount, the first tracking control is executed. It is configured as follows: In a vehicle driving assistance device, the control device is configured to predict the inter-vehicle distance and the host vehicle speed when the first following control is executed based on the traveling speed of the preceding vehicle when the first following control is executed, and to predict the inter-vehicle distance and the host vehicle speed when the second following control is executed based on the traveling speed of the preceding vehicle when the second following control is executed. Vehicle driving assistance device.

6. The vehicle driving support device according to any one of claims 1 to 5, The control device includes: When a predetermined execution condition is satisfied that a reduction in the amount of energy consumed by a drive device of the host vehicle is requested, a change in the inter-vehicle distance and the host vehicle speed when the first following control is executed is predicted, and the amount of energy consumed by the drive device of the host vehicle when the first following control is executed is predicted as the first consumed energy amount based on the inter-vehicle distance and the host vehicle speed when it is assumed that they have changed as predicted, and a change in the inter-vehicle distance and the host vehicle speed when the second following control is executed is predicted, and the amount of energy consumed when the second following control is executed is predicted as the second consumed energy amount. Vehicle driving assistance device.

7. The vehicle driving support device according to any one of claims 1 to 6, The second following control is a control for decelerating the host vehicle by coasting the host vehicle when the host vehicle speed increases and reaches an upper limit of the predetermined speed range, accelerating the host vehicle when the host vehicle speed decreases and reaches a lower limit of the predetermined speed range, or accelerating the host vehicle when the inter-vehicle distance increases and reaches an upper limit of the predetermined distance range, and decelerating the host vehicle by coasting the host vehicle when the inter-vehicle distance decreases and reaches a lower limit of the predetermined distance range. Vehicle driving assistance device.

8. The vehicle driving support device according to any one of claims 1 to 7, The control device is configured to set a range of the host vehicle speed that is permissible depending on a driving environment of the host vehicle as the predetermined speed range, or to set a range of the inter-vehicle distance that is permissible depending on a driving environment of the host vehicle as the predetermined distance range. Vehicle driving assistance device.

9. A vehicle driving assistance method for causing a host vehicle to travel by a first following control in which an acceleration / deceleration of the host vehicle is automatically controlled so that an inter-vehicle distance between the host vehicle and a preceding vehicle is maintained at a predetermined distance, and the host vehicle travels following the preceding vehicle, or a second following control in which an acceleration / deceleration of the host vehicle is automatically controlled so that a host vehicle speed, which is a traveling speed of the host vehicle, is maintained at a speed within a predetermined speed range, or the inter-vehicle distance is maintained at a distance within a predetermined distance range, when a predetermined execution condition is met that a reduction in the amount of energy consumed by a drive device of the host vehicle is requested, predicting changes in the inter-vehicle distance and the host vehicle speed when the first following control is executed, and predicting the amount of energy consumed by the drive device of the host vehicle when the first following control is executed as a first consumed energy amount based on the inter-vehicle distance and the host vehicle speed when it is assumed that they have changed as predicted, and predicting changes in the inter-vehicle distance and the host vehicle speed when the second following control is executed, and predicting the amount of energy consumed when the second following control is executed as a second consumed energy amount based on the inter-vehicle distance and the host vehicle speed when it is assumed that they have changed as predicted, When the second consumed energy amount is smaller than the first consumed energy amount, the second tracking control is executed; When the second consumed energy amount is equal to or greater than the first consumed energy amount, the first tracking control is executed.

1. A vehicle driving assistance method comprising: The second tracking control is a control for accelerating the host vehicle by optimal acceleration control, which operates the drive device at an operating point where an amount of energy consumption of the drive device is minimum or approximately minimum, to accelerate the host vehicle, when accelerating the host vehicle, and for decelerating the host vehicle by coasting control, which causes the host vehicle to coast. A vehicle driving assistance method.

10. A vehicle driving assistance program for causing a host vehicle to travel by a first following control for automatically controlling acceleration / deceleration of the host vehicle so that a vehicle-to-vehicle distance between the host vehicle and a preceding vehicle is maintained at a predetermined distance, or a second following control for automatically accelerating / decelerating the host vehicle so that a host vehicle speed, which is a traveling speed of the host vehicle, is maintained at a speed within a predetermined speed range or the vehicle-to-vehicle distance is maintained at a distance within a predetermined distance range, when a predetermined execution condition is met that a reduction in the amount of energy consumed by a drive device of the host vehicle is requested, predicting changes in the inter-vehicle distance and the host vehicle speed when the first following control is executed, and predicting the amount of energy consumed by the drive device of the host vehicle when the first following control is executed as a first consumed energy amount based on the inter-vehicle distance and the host vehicle speed when it is assumed that they have changed as predicted, and predicting changes in the inter-vehicle distance and the host vehicle speed when the second following control is executed, and predicting the amount of energy consumed when the second following control is executed as a second consumed energy amount based on the inter-vehicle distance and the host vehicle speed when it is assumed that they have changed as predicted, When the second consumed energy amount is smaller than the first consumed energy amount, the second tracking control is executed; When the second consumed energy amount is equal to or greater than the first consumed energy amount, the first tracking control is executed. In vehicle driving assistance programs, The second tracking control is a control for accelerating the host vehicle by optimal acceleration control, which operates the drive device at an operating point where an amount of energy consumption of the drive device is minimum or approximately minimum, to accelerate the host vehicle, when accelerating the host vehicle, and for decelerating the host vehicle by coasting control, which causes the host vehicle to coast. Vehicle driving assistance program.

Images