Vehicle driving support device

Abstract

To provide a vehicle driving support device capable of allowing an own vehicle to coast over a long distance while traveling on a downhill road during execution of autonomous driving control.SOLUTION: A vehicle driving support device 10 executes autonomous driving control allowing an own vehicle 100 to travel autonomously while increasing and decreasing a vehicle speed of the own vehicle within a range between an upper limit vehicle speed and a lower limit vehicle speed. When the vehicle speed increases and reaches the upper limit vehicle speed during execution of the autonomous driving control, the vehicle driving support device causes the own vehicle to coast. When the vehicle speed decreases and reaches the lower limit vehicle speed, the vehicle driving support device causes the own vehicle to perform powered driving. When a coasting permission condition is met while the own vehicle is performing powered driving during the execution of the autonomous control, the vehicle driving support device causes the own vehicle to coast even if the vehicle speed of the own vehicle is lower than the upper limit vehicle speed. The coasting permission condition is that a road a predetermined distance ahead of the own vehicle on which the own vehicle is expected to travel is a downhill road.SELECTED DRAWING: Figure 5

Description

Technical Field

[0001] The present invention relates to a vehicle driving support device.

Background Art

[0002] There is known a vehicle driving support device that executes autonomous driving control to autonomously drive a host vehicle while increasing or decreasing the vehicle speed of the host vehicle. As such a vehicle driving support device, when the vehicle speed of the host vehicle reaches a preset upper limit vehicle speed during the execution of the autonomous driving control, the host vehicle is coasted, and when the vehicle speed of the host vehicle reaches a preset lower limit vehicle speed, the host vehicle is configured to accelerate (see, for example, Patent Document 1). The vehicle driving support device aims to reduce the amount of energy consumed (energy consumption amount) for driving the host vehicle by coasting the host vehicle.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

[0004] When the host vehicle is traveling on a downhill road, even if the host vehicle is coasting, the vehicle speed of the host vehicle increases. Therefore, when the host vehicle is traveling on a downhill road during the execution of the autonomous driving control, coasting the host vehicle is advantageous for reducing the energy consumption amount. Therefore, when the host vehicle starts to travel on a downhill road, it is desirable to coast the host vehicle.

[0005] However, if the vehicle speed of the host vehicle is close to the upper limit vehicle speed when the host vehicle reaches the start point of the downhill road, the vehicle speed of the host vehicle may reach the upper limit vehicle speed while the host vehicle is traveling on the downhill road, and it may become necessary to apply a braking force to the host vehicle to decelerate the host vehicle. Applying a braking force to the host vehicle in this way to decelerate the host vehicle is not preferable for reducing the energy consumption amount.

[0006] An object of the present invention is to provide a vehicle driving support device that can coast the host vehicle over a long distance while the host vehicle is traveling on a downhill road during execution of autonomous driving control.

[0007] The vehicle driving support device according to the present invention includes a control device that executes autonomous driving control for autonomously driving the host vehicle while increasing and decreasing the vehicle speed of the host vehicle between an upper limit vehicle speed and a lower limit vehicle speed. When the vehicle speed rises and reaches the upper limit vehicle speed during execution of the autonomous driving control, the control device is configured to coast the host vehicle, and when the vehicle speed drops and reaches the lower limit vehicle speed, the control device is configured to drive the host vehicle forward. Further, when the coasting permission condition is satisfied while the control device is driving the host vehicle forward during execution of the autonomous driving control, the control device is configured to coast the host vehicle even if the vehicle speed of the host vehicle is lower than the upper limit vehicle speed. The coasting permission condition is a condition that a road a predetermined distance ahead of the host vehicle and on which the host vehicle is scheduled to travel is a downhill road.

[0008] According to the vehicle driving support device of the present invention, when the coasting permission condition is satisfied, coasting of the host vehicle is started even if the vehicle speed of the host vehicle has not reached the upper limit vehicle speed. Therefore, when the host vehicle reaches the start point of the downhill road, the vehicle speed of the host vehicle is sufficiently low. Accordingly, during execution of the autonomous driving control, the host vehicle can be coasted over a long distance while the host vehicle is traveling on the downhill road. As a result, the amount of energy (energy consumption amount) consumed to drive the host vehicle can be made less. Further, according to this, when the host vehicle reaches the start point of the downhill road, the vehicle speed of the host vehicle is low. Therefore, the host vehicle can be coasted over a longer distance while the host vehicle is traveling on the downhill road. For this reason, the energy consumption amount can be made even less.

[0009] Further, in the vehicle driving support device according to the present invention, the coasting permission condition may include a condition that the vehicle speed is less than the upper limit vehicle speed and equal to or higher than a predetermined vehicle speed. In this case, the predetermined vehicle speed is a vehicle speed that is less than the upper limit vehicle speed and equal to or higher than the lower limit vehicle speed, and can be set to a lower vehicle speed as the amount of increase in the vehicle speed while the host vehicle is traveling on the downhill road is larger.

[0010] According to the vehicle driving support device of the present invention, the larger the amount of increase in the vehicle speed while the host vehicle is traveling on the downhill road, the earlier the coasting of the host vehicle is started while the vehicle speed is low. For this reason, when the host vehicle reaches the start point of the downhill road, the vehicle speed of the host vehicle is sufficiently low. Therefore, during the execution of the autonomous driving control, while the host vehicle is traveling on the downhill road, the host vehicle can be coasted for a longer distance. As a result, the amount of energy consumed to drive the host vehicle can be made less.

[0011] Further, in the vehicle driving support device according to the present invention, the coasting permission condition may include a condition that the vehicle speed is less than the upper limit vehicle speed and equal to or higher than a predetermined vehicle speed. In this case, the predetermined vehicle speed is a vehicle speed less than the upper limit vehicle speed, and can be set to a lower vehicle speed as the amount of increase in the vehicle speed while the host vehicle is traveling on the downhill road is larger.

[0012] According to the vehicle driving support device of the present invention, the larger the amount of increase in the vehicle speed while the host vehicle is traveling on the downhill road, the earlier the coasting of the host vehicle is started while the vehicle speed is low. For this reason, when the host vehicle reaches the start point of the downhill road, the vehicle speed of the host vehicle is sufficiently low. Therefore, during the execution of the autonomous driving control, while the host vehicle is traveling on the downhill road, the host vehicle can be coasted for a longer distance. As a result, the amount of energy consumed to drive the host vehicle can be made less.

[0013] Further, in the vehicle driving support device according to the present invention, the coasting permission condition may include a condition that the distance between the host vehicle and the start point of the downhill road is equal to or less than a predetermined distance. In this case, the predetermined distance may be set to a longer distance as the amount of increase in the vehicle speed while the host vehicle is traveling on the downhill road is larger.

[0014] According to the vehicle driving support device of the present invention, the larger the amount of increase in the vehicle speed while the host vehicle is traveling on the downhill road, the earlier the coasting of the host vehicle is started from the point where the host vehicle has left the downhill road. For this reason, when the host vehicle reaches the start point of the downhill road, the vehicle speed of the host vehicle is sufficiently low. Therefore, when executing the autonomous driving control, while the host vehicle is traveling on the downhill road, the host vehicle can be coasted for a longer distance. As a result, the amount of energy consumed for driving the host vehicle can be made less.

[0015] In the vehicle driving support device according to the present invention, the coasting permission condition may include a condition that when the host vehicle starts to coast at the current time, the vehicle speed reaches the lower limit vehicle speed when the host vehicle reaches the start point of the downhill road.

[0016] According to the vehicle driving support device of the present invention, it is possible to prevent the vehicle speed from falling below the lower limit vehicle speed while the host vehicle is coasting.

[0017] Further, in the vehicle driving support device according to the present invention, the coasting permission condition may also be a condition that is satisfied when there is no following vehicle and the amount of increase in the vehicle speed while the host vehicle is traveling on the downhill road is equal to or greater than the difference between the upper limit vehicle speed and the lower limit vehicle speed. In this case, after the coasting permission condition is satisfied and the host vehicle starts to coast, when the vehicle speed becomes lower than the lower limit vehicle speed, the control device may give a coasting continuation notice to the user of the host vehicle and may be configured to continue the coasting of the host vehicle. Further, the coasting continuation notice is, for example, a notice for notifying the user to continue the coasting of the host vehicle because there is a downhill road on the road on which the host vehicle is scheduled to travel.

[0018] According to the vehicle driving support device of the present invention, even when the vehicle speed falls below the lower limit vehicle speed, the coasting of the own vehicle is continued with the user's consent. Therefore, when the own vehicle reaches the start point of a downhill road, the vehicle speed of the own vehicle is sufficiently low. Therefore, when executing the autonomous driving control, while the own vehicle is traveling on a downhill road, the own vehicle can be coasted for a longer distance. As a result, the amount of energy consumed to drive the own vehicle can be made less.

[0019] The components of the present invention are not limited to the embodiments of the present invention described below with reference to the drawings. Other objects, other features, and attendant advantages of the present invention will be readily understood from the description of the embodiments of the present invention.

Brief Description of the Drawings

[0020]

Figure 1

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Figure 10

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Mode for Carrying Out the Invention

[0021] Hereinafter, with reference to the drawings, a vehicle driving support device according to an embodiment of the present invention will be described. FIG. 1 shows a vehicle driving support device 10 according to an embodiment of the present invention. The vehicle driving support device 10 is mounted on the host vehicle 100. Hereinafter, the case where the user of the host vehicle 100 is a person who rides on the host vehicle 100 and drives the host vehicle 100 (that is, the driver of the host vehicle 100) will be taken as an example to describe the vehicle driving support device 10.

[0022] However, the user of the host vehicle 100 may be a person who remotely drives the host vehicle 100 without riding on the host vehicle 100 (that is, the remote operator of the host vehicle 100). When the user of the host vehicle 100 is a remote operator, the vehicle driving support device 10 is mounted on each of the host vehicle 100 and remote operation equipment installed outside the host vehicle 100 for remotely driving the host vehicle 100, and the functions of the vehicle driving support device 10 described below are respectively shared by the vehicle driving support device 10 mounted on the host vehicle 100 and the vehicle driving support device 10 mounted on the remote operation equipment.

[0023] As shown in FIG. 1, the vehicle driving support device 10 includes an ECU (Electronic Control Unit) 90 as a control device. The ECU 90 includes a microcomputer as a main part. The microcomputer includes a CPU, a ROM, a RAM, a storage medium such as a non-volatile memory, and an interface, etc. The CPU is configured to realize various functions by executing instructions or programs or routines stored in a computer-readable storage medium. In particular, in this example, the vehicle driving support device 10 stores a program for realizing various controls executed by the vehicle driving support device 10 in a storage medium.

[0024] Note that in this example, the vehicle driving support device 10 includes only one ECU 90, but it may be configured to include a plurality of ECUs and divide the functions of the vehicle driving support device 10 described below among the respective ECUs.

[0025] Also, the vehicle driving support device 10 may be configured to be able to update (update) a program stored in a storage medium by wireless communication (for example, Internet communication) with an external device.

[0026] As shown in FIG. 1, a driving device 20 and a braking device 30 are mounted on the host vehicle 100.

[0027] The driving device 20 is a device that applies a driving force for propelling the host vehicle 100 to the host vehicle 100. In this example, the driving device 20 includes an internal combustion engine 21 and a motor generator 22. The internal combustion engine 21 and the motor generator 22 are electrically connected to the ECU 90. The vehicle driving support device 10 controls the magnitude of the driving force applied to the host vehicle 100 by controlling the operations of the internal combustion engine 21 and the motor generator 22.

[0028] The braking device 30 is a device that applies a braking force for braking the host vehicle 100 to the host vehicle 100. In this example, the braking device 30 includes a hydraulic braking device 31. The hydraulic braking device 31 is electrically connected to the ECU 90. The vehicle driving support device 10 controls the magnitude of the braking force applied to the host vehicle 100 by controlling the operation of the hydraulic braking device 31.

[0029] Furthermore, the host vehicle 100 is equipped with an eco-driving support request operator 41, an eco-level setting operator 42, a vehicle speed detection device 50, a surrounding information acquisition device 60, and a road information acquisition device 70.

[0030] The eco-driving support request operator 41 is a device that the driver operates to request the execution of eco-autonomous driving control. The eco-autonomous driving control will be described later. The eco-driving support request operator 41 is electrically connected to the ECU 90. When the eco-driving support request operator 41 is operated when the vehicle driving support device 10 is not executing the eco-autonomous driving control, the vehicle driving support device 10 determines that the execution of the eco-autonomous driving control is requested. On the other hand, when the eco-driving support request operator 41 is operated when the vehicle driving support device 10 is executing the eco-autonomous driving control, the vehicle driving support device 10 determines that the stop of the eco-autonomous driving control is requested.

[0031] The eco-level setting operator 42 is a device that the driver operates to set the required eco-level LVreq. The required eco-level LVreq indicates the degree of the amount of energy consumption that the driver requests to reduce by the eco-autonomous driving control. The degree of the amount of energy consumption that is requested to be reduced by the eco-autonomous driving control is greater as the required eco-level LVreq is higher. In this example, the driver can set any one of the strong eco-level LVs, medium eco-level LVm, and weak eco-level LVw as the required eco-level LVreq by operating the eco-level setting operator 42. The eco-level setting operator 42 is electrically connected to the ECU 90. The vehicle driving support device 10 acquires the required eco-level LVreq set by the driver operating the eco-level setting operator 42.

[0032] The energy consumption amount is the amount of energy consumed to drive the host vehicle 100.

[0033] The vehicle speed detection device 50 is a device that detects the traveling speed of the host vehicle 100. The vehicle speed detection device 50 is, for example, a wheel speed sensor attached to each wheel of the host vehicle 100. The vehicle speed detection device 50 is electrically connected to the ECU 90. The vehicle driving support device 10 acquires the traveling speed of the host vehicle 100 as the host vehicle speed V by the vehicle speed detection device 50.

[0034] The surrounding information acquisition device 60 is a device that acquires information on the situation around the host vehicle 100 as surrounding information IS. In this example, the surrounding information acquisition device 60 includes an electromagnetic wave sensor 61 and an image sensor 62.

[0035] The electromagnetic wave sensor 61 is a device that acquires information on targets existing in the surroundings including the front, rear, left, and right of the host vehicle 100 as target information IO. The electromagnetic wave sensor 61 is a sensor such as a millimeter wave radar. The electromagnetic wave sensor 61 is electrically connected to the ECU 90. The vehicle driving support device 10 acquires the target information IO as the surrounding information IS.

[0036] The image sensor 62 is a device that images the surroundings including the front, rear, left, and right of the host vehicle 100 and acquires image data on the surroundings of the host vehicle 100 as image information IC. The image sensor 62 is a sensor such as a camera. The image sensor 62 is electrically connected to the ECU 90. The vehicle driving support device 10 acquires the image information IC as the surrounding information IS.

[0037] The road information acquisition device 70 is a device that acquires information on the road in the area where the host vehicle 100 is traveling as road information IR. In this example, the road information acquisition device 70 includes a GPS signal receiver 71 and a map database 72.

[0038] The GPS signal receiver 71 is a device that receives GPS signals. The GPS signal receiver 71 is electrically connected to the ECU 90. The vehicle driving support device 10 acquires GPS signals via the GPS signal receiver 71. The vehicle driving support device 10 acquires the current position Pn of the host vehicle 100 based on the acquired GPS signals.

[0039] The map database 72 is a database that stores map data including information on roads. The map database 72 is electrically connected to the ECU 90. The vehicle driving support device 10 acquires, as road information IR, information on the road on which the host vehicle 100 is scheduled to travel from the map database 72 based on the current position Pn of the host vehicle 100.

[0040] <Operation of Vehicle Driving Support Device> Next, the operation of the vehicle driving support device 10 will be described.

[0041] When execution of eco-driving control is requested, the vehicle driving support device 10 is configured to execute eco-driving control as autonomous driving control (or autonomous operation control or automatic driving control). In this example, the eco-driving control includes eco-inter-vehicle distance control and eco-driving speed control.

[0042] As shown in FIG. 2, the eco-inter-vehicle distance control is a control for autonomously driving the host vehicle 100 by controlling the acceleration and deceleration of the host vehicle 100 such that the inter-vehicle distance DF moves back and forth between the upper limit inter-vehicle distance DFupper and the lower limit inter-vehicle distance DFlower when the preceding vehicle 200 exists.

[0043] More specifically, when the inter-vehicle distance DF decreases and reaches the lower limit inter-vehicle distance DFlower while the host vehicle 100 is being powered by power running control in the eco-inter-vehicle distance control, the host vehicle 100 is coasted by coasting control, and when the inter-vehicle distance DF increases and reaches the upper limit inter-vehicle distance DFupper while the host vehicle 100 is being coasted by coasting control, the host vehicle 100 is powered by power running control.

[0044] Furthermore, the preceding vehicle 200 is a vehicle traveling in the own vehicle travel lane LNown within a range of a predetermined forward distance DFth ahead of the own vehicle 100. The own vehicle travel lane LNown is the lane in which the own vehicle 100 is traveling. The vehicle driving support device 10 determines whether or not the preceding vehicle 200 exists based on the surrounding information IS. Also, the vehicle driving support device 10 acquires the inter-vehicle distance DF based on the surrounding information IS.

[0045] As shown in FIG. 3, the eco-driving speed control is a control for autonomously driving the own vehicle 100 by controlling the acceleration and deceleration of the own vehicle 100 so that the own vehicle speed V moves back and forth between the upper limit vehicle speed Vupper and the lower limit vehicle speed Vlower when the preceding vehicle 200 does not exist.

[0046] More specifically, when the own vehicle speed V increases and reaches the upper limit vehicle speed Vupper while the own vehicle 100 is being powered by the power running control, the eco-driving speed control coasts the own vehicle 100 by the coasting control, and when the own vehicle speed V decreases and reaches the lower limit vehicle speed Vlower while the own vehicle 100 is being coasted by the coasting control, the eco-driving speed control powers the own vehicle 100 by the power running control.

[0047] Furthermore, the power running control is a control for powering the own vehicle 100 by applying a driving force to the own vehicle 100 by the drive device 20. Also, the coasting control is a control for coasting the own vehicle 100 by stopping the operation of the drive device 20 and blocking the driving force transmission path for applying a driving force from the drive device 20 to the own vehicle 100.

[0048] Furthermore, the power running control may be an optimal power running control. The optimal power running control is a control for powering the own vehicle 100 by applying a driving force to the own vehicle 100 by the drive device 20 while operating the drive device 20 so that the amount of energy consumed by the drive device 20 for generating the driving force becomes as low as possible.

[0049] Further, in this example, the upper limit vehicle speed Vupper is the set vehicle speed Vset. The set vehicle speed Vset is the vehicle speed that the driver requests for the host vehicle 100 when the host vehicle 100 is traveling under the eco-driving speed control. The driver can arbitrarily set the set vehicle speed Vset.

[0050] Next, the forced coasting control will be described. The vehicle driving support device 10 executes the routine shown in FIGS. 4 and 5 at a predetermined calculation cycle, and executes the forced coasting control according to various conditions. In this example, the forced coasting control is the same control as the coasting control.

[0051] At a predetermined timing, the vehicle driving support device 10 starts processing from step S400 of the routine shown in FIG. 4, advances the processing to step S405, and determines whether execution of the eco autonomous driving control is requested.

[0052] When execution of the eco autonomous driving control is requested, the vehicle driving support device 10 determines "Yes" at step S405, advances the processing to step S410, and determines whether the value of the forced coasting control execution flag Xcoast is "0". The value of the forced coasting control execution flag Xcoast is set to "1" when the forced coasting control is being executed. On the other hand, the value of the forced coasting control execution flag Xcoast is set to "0" when the forced coasting control is not being executed.

[0053] When the value of the forced coasting control execution flag Xcoast is "0", the vehicle driving support device 10 determines "Yes" at step S410, advances the processing to step S415, and determines whether the value of the power running control execution flag Xpower is "1". The value of the power running control execution flag Xpower is set to "1" when the power running control is being executed. On the other hand, the value of the power running control execution flag Xpower is set to "0" when the power running control is not being executed.

[0054] When the value of the power running control execution flag Xpower is "1", the vehicle driving support device 10 determines "Yes" in step S415, advances the process to step S420, and determines whether the downhill road condition C1 is satisfied.

[0055] The downhill road condition C1 is a coasting permission condition (first coasting permission condition) that the road a predetermined distance (predetermined downhill road determination distance DSLth) ahead of the host vehicle 100 and on which the host vehicle 100 is scheduled to travel is a downhill road SLdown. The vehicle driving support device 10 determines whether the downhill road condition C1 is satisfied based on the road information IR and / or the surrounding information IS.

[0056] When the downhill road condition C1 is satisfied, the vehicle driving support device 10 determines "Yes" in step S420, advances the process to step S425, and determines whether the preceding and following vehicle condition C2 is satisfied.

[0057] The preceding and following vehicle condition C2 is a coasting permission condition (second coasting permission condition) that the preceding vehicle 200 and the following vehicle 300 exist. As described above, the preceding vehicle 200 is another vehicle traveling in the host vehicle's travel lane LNown within a predetermined forward distance DFth ahead of the host vehicle 100. On the other hand, the following vehicle 300 is another vehicle traveling in the host vehicle's travel lane LNown within a predetermined rearward distance DRth or less behind the host vehicle 100 as shown in FIG. 2. Note that the host vehicle's travel lane LNown is the lane in which the host vehicle 100 is currently traveling. Also, the predetermined forward distance DFth and the predetermined rearward distance DRth may be the same distance or different distances.

[0058] Note that the vehicle driving support device 10 determines whether the preceding and following vehicle condition C2 is satisfied based on the surrounding information IS.

[0059] When the front and rear vehicle condition C2 is satisfied, the vehicle driving support device 10 determines "Yes" in step S425, advances the process to step S430, and executes the routine shown in FIG. 5. Therefore, when the vehicle driving support device 10 advances the process to step S430, it starts the process from step S500 of the routine shown in FIG. 5, advances the process to step S505, and acquires a deceleration amount ΔVdown and an acceleration amount ΔVup.

[0060] The deceleration amount ΔVdown is the amount by which the vehicle speed V decreases until the host vehicle 100 reaches the start point SLstart of the downhill road (the point where the downhill road SLdown starts) when the host vehicle 100 starts coasting now. In this example, the vehicle driving support device 10 acquires the deceleration amount ΔVdown according to the following formula (1).

[0061] ΔVdown = -V + √(V 2 + 2·(G + g·sinθ1)·D1) …(1)

[0062] In the above formula (1), V is the host vehicle speed V, G is the coasting acceleration G, g is the gravitational acceleration g, θ1 is the road gradient θ1 before the downhill road, and D1 is the distance D1 before the downhill road.

[0063] The distance D1 before the downhill road is the distance between the current position Pn of the host vehicle 100 and the start point SLstart of the downhill road. The vehicle driving support device 10 acquires the distance D1 before the downhill road based on the road information IR.

[0064] Furthermore, the road gradient θ1 before the downhill road is the gradient of the road between the current position Pn of the host vehicle 100 and the start point SLstart of the downhill road. The vehicle driving support device 10 acquires the road gradient θ1 before the downhill road based on the road information IR. Note that in the above formula (1), the road gradient θ1 before the downhill road is zero when the road is a flat road, a negative value when the road is an uphill road, and a negative value when the road is a downhill road.

[0065] Moreover, the coasting acceleration G is the acceleration of the host vehicle 100 when the host vehicle 100 is coasting on a flat road (a flat road, that is, a road with a gradient of zero). Therefore, the absolute value of the coasting acceleration G becomes larger as the running resistance against the host vehicle 100 becomes larger, taking a negative value. In other words, when the running resistance against the host vehicle 100 consists of the rolling resistance and the air resistance of the tires of the host vehicle 100, the absolute value of the coasting acceleration G becomes larger as the rolling resistance becomes larger, taking a negative value, and the absolute value of the coasting acceleration G becomes larger as the air resistance becomes larger, taking a negative value.

[0066] Moreover, the coasting acceleration G takes a negative value when the host vehicle 100 decelerates, and takes a positive value when the host vehicle 100 accelerates. However, when the host vehicle 100 is coasting on a flat road, since the host vehicle 100 decelerates, the coasting acceleration G actually takes a negative value.

[0067] Moreover, in this example, the road between the current position Pn of the host vehicle 100 and the start point SLstart of the downhill road is a flat road or an uphill road. When the host vehicle 100 is coasting on a flat road or an uphill road, since the vehicle speed V decreases, the deceleration amount ΔVdown obtained by the above formula 1 takes a negative value.

[0068] Alternatively, the vehicle driving support device 10 may be configured to obtain the deceleration amount ΔVdown according to the following formula 2.

[0069] ΔVdown=(G + g·sinθ1)×D1 / Vset …(2)

[0070] Also in the above formula 2, G is the coasting acceleration G, g is the gravitational acceleration g, θ1 is the road gradient θ1 before the downhill road, and D1 is the distance D1 before the downhill road. Moreover, in the above formula 2, Vset is the set vehicle speed Vset (that is, the upper limit vehicle speed Vupper).

[0071] Similar to the deceleration amount ΔVdown obtained by the above formula 1, the deceleration amount ΔVdown obtained by the above formula 2 also takes a negative value. Also, the deceleration amount ΔVdown obtained by the above formula 2 is the amount by which the vehicle speed V decreases during the time required for the host vehicle 100 to travel the downhill road front distance D1 at the set vehicle speed Vset. In other words, the deceleration amount ΔVdown obtained by the above formula 2 is the amount by which the vehicle speed V of the host vehicle 100 decreases at least until the host vehicle 100 reaches the start point SLstart of the downhill road when the coasting of the host vehicle 100 is started at the current time.

[0072] On the other hand, the acceleration amount ΔVup is the amount by which the vehicle speed V increases when the host vehicle 100 is coasted and travels from the start point SLstart of the downhill road to the end point SLend of the downhill road (the point where the downhill road SLdown ends). In this example, the vehicle driving support device 10 obtains the acceleration amount ΔVup according to the following formula 3.

[0073] ΔVup=-V+√(V 2 +2·(G+g·sinθ2)·D2) …(3)

[0074] Also in the above formula 3, V is the vehicle speed V, G is the coasting acceleration G, and g is the gravitational acceleration g. Also, in the above formula 3, θ2 is the downhill road gradient θ2, and D2 is the downhill road distance D2.

[0075] The downhill road distance D2 is the distance between the start point SLstart of the downhill road and the end point SLend of the downhill road. That is, the downhill road distance D2 is the distance of the downhill road SLdown. The vehicle driving support device 10 obtains the downhill road distance D2 based on the road information IR.

[0076] Also, the downhill road gradient θ2 is the gradient of the downhill road SLdown. The vehicle driving support device 10 obtains the downhill road gradient θ2 based on the road information IR. Note that in the above formula 3, the downhill road gradient θ2 is a negative value.

[0077] Also, the acceleration amount ΔVup obtained by the above formula 3 takes a positive value except when the downhill road gradient θ2 is extremely small.

[0078] Alternatively, the vehicle driving support device 10 may be configured to obtain the acceleration amount ΔVup by the following formula 4.

[0079] ΔVup = (G + g·sinθ2) × D2 / Vset …(4)

[0080] In the above formula 4 as well, G is the coasting acceleration G, g is the gravitational acceleration g, θ2 is the downhill road gradient θ2, D2 is the downhill road distance D2, and Vset is the set vehicle speed Vset (i.e., the upper limit vehicle speed Vupper).

[0081] Similar to the acceleration amount ΔVup obtained by the above formula 3, the acceleration amount ΔVup obtained by the above formula 4 also takes a positive value. Also, the acceleration amount ΔVup obtained by the above formula 4 is the amount of the vehicle speed V that increases during the time required for the host vehicle 100 to travel the downhill road distance D2 at the set vehicle speed Vset. In other words, the acceleration amount ΔVup obtained by the above formula 4 is the minimum amount of the vehicle speed V that increases until the host vehicle 100 reaches the downhill road end point SLend when starting to coast the host vehicle 100 at the downhill road start point SLstart.

[0082] Next, the vehicle driving support device 10 proceeds with the process to step S510 and determines whether the strong eco level condition C3 is satisfied.

[0083] The strong eco level condition C3 is a condition that the required eco level LVreq is equal to or higher than a predetermined eco level LVth. In this example, the strong eco level condition C3 is satisfied when the required eco level LVreq is set to the strong eco level LVs.

[0084] When the strong eco level condition C3 is satisfied, the vehicle driving support device 10 determines "Yes" in step S510 and proceeds with the process to step S515 to determine whether the high acceleration amount condition C4 is satisfied.

[0085] The high acceleration amount condition C4 is a coasting permission condition (the third coasting permission condition) that when the host vehicle 100 starts to coast now and travels to the end point SLend of the downhill road while coasting, the host vehicle speed V reaches the upper limit vehicle speed Vupper when the host vehicle 100 reaches the end point SLend of the downhill road. That is, the high acceleration amount condition C4 is established when the following formula 5 holds.

[0086] (Vupper - V) + |ΔVdown| ≤ ΔVup …(5)

[0087] In the above formula 5, Vupper is the upper limit vehicle speed Vupper, V is the host vehicle speed V, ΔVdown is the deceleration amount ΔVdown, and ΔVup is the acceleration amount ΔVup.

[0088] Therefore, when the downhill road condition C1 is established while the distance between the current position Pn of the host vehicle 100 and the start point SLstart of the downhill road is sufficiently long, the high acceleration amount condition C4 is established at the timing when the host vehicle speed V becomes the upper limit vehicle speed Vupper when the host vehicle 100 reaches the end point SLend of the downhill road if the host vehicle 100 starts to coast now and travels to the end point SLend of the downhill road while coasting.

[0089] In addition, the high acceleration amount condition C4 is established when the host vehicle speed V reaches a certain vehicle speed or higher, and moreover, the larger the acceleration amount ΔVup is, the more likely it is to be established while the host vehicle speed V is small. Therefore, the high acceleration amount condition C4 is a condition that is established when the host vehicle speed V is smaller than the upper limit vehicle speed Vupper and equal to or higher than a predetermined vehicle speed Vth_1. The predetermined vehicle speed Vth_1 is a vehicle speed smaller than the upper limit vehicle speed Vupper, and it can also be said that the lower the vehicle speed is set, the larger the acceleration amount ΔVup (the acceleration amount of the host vehicle speed V while the host vehicle 100 is traveling on the downhill road SLdown). In addition, the predetermined vehicle speed Vth_1 is, for example, the vehicle speed represented by the following formula 6.

[0090] Vth_1 = Vupper - (ΔVup - ΔVdown) …(6)

[0091] Furthermore, it can also be said that the high acceleration amount condition C4 is satisfied when the downhill approach distance D1 becomes equal to or less than a predetermined distance Dth_1. In this case, the high acceleration amount condition C4 is satisfied as long as the downhill approach distance D1 is large while the acceleration amount ΔVup is large. Therefore, the high acceleration amount condition C4 is a condition that is satisfied when the distance between the host vehicle 100 and the start point SLstart of the downhill road is equal to or less than the predetermined distance Dth_1. It can also be said that the predetermined distance Dth_1 is set to a longer distance as the acceleration amount ΔVup (the increase in the host vehicle speed V while the host vehicle 100 is traveling on the downhill road SLdown) is larger. Note that the predetermined distance Dth_1 is a distance that satisfies the relationship expressed by, for example, the following equation 7.

[0092] (Vupper - V)+ΔVdown = ΔVup …(7)

[0093] Furthermore, the high acceleration amount condition C4 is also a condition that is satisfied when the acceleration amount ΔVup (the increase in the host vehicle speed V while the host vehicle 100 is traveling on the downhill road SLdown) is equal to or greater than the control width Wcontrol (the difference between the upper limit vehicle speed Vupper and the lower limit vehicle speed Vlower).

[0094] Note that the high acceleration amount condition C4 may be satisfied when the following equation 8 holds.

[0095] (Vupper - V)+|ΔVdown|≦Min(ΔVth,ΔVup) …(8)

[0096] In the above equation 8 as well, Vupper is the upper limit vehicle speed Vupper, V is the host vehicle speed V, ΔVdown is the deceleration amount ΔVdown, and ΔVup is the acceleration amount ΔVup. Also, ΔVth is an arbitrary value determined in advance and is a value larger than the control width Wcontrol. The control width Wcontrol is the difference between the upper limit vehicle speed Vupper and the lower limit vehicle speed Vlower (Wcontrol = Vupper - Vlower).

[0097] According to this, when the acceleration increase amount ΔVup is larger than the value ΔVth, since the acceleration increase amount ΔVup is limited to the value ΔVth, it is possible to prevent the vehicle speed V from becoming extremely low due to the extremely large acceleration increase amount ΔVup.

[0098] When the high acceleration increase amount condition C4 is satisfied, the vehicle driving support device 10 determines "Yes" in step S515, proceeds with the process to step S520, and stops the eco cruise control. Next, the vehicle driving support device 10 proceeds with the process to step S525 and starts the forced coasting control.

[0099] Next, the vehicle driving support device 10 proceeds with the process to step S530, sets the value of the power running control execution flag Xpower to "0", and sets the value of the forced coasting control execution flag Xcoast to "1". Next, the vehicle driving support device 10 proceeds with the process to step S595 and once ends the process of this routine. As a result, since the forced coasting control is started, the vehicle speed V decreases.

[0100] On the other hand, when the high acceleration increase amount condition C4 is not satisfied, the vehicle driving support device 10 determines "No" in step S515, directly proceeds with the process to step S595, and once ends the process of this routine. In this case, the eco cruise control is continued.

[0101] Also, when the strong eco level condition C3 is not satisfied, the vehicle driving support device 10 determines "No" in step S510, proceeds with the process to step S535, and determines whether or not the appropriate deceleration amount condition C5 is satisfied.

[0102] The appropriate deceleration amount condition C5 is a coasting permission condition (fourth coasting permission condition) that when the host vehicle 100 starts to coast now, the vehicle speed V does not become lower than the lower limit vehicle speed Vlower when the host vehicle 100 reaches the downhill road start point SLstart. That is, the appropriate deceleration amount condition C5 is satisfied when the following formula 9 holds.

[0103] (Vupper - V)+|ΔVdown|≦Min(Wcontrol,ΔVup) …(9)

[0104] In Equation (9) above, Vupper is the upper limit vehicle speed Vupper, V is the own vehicle speed V, ΔVdown is the deceleration amount ΔVdown, Wcontrol is the control width Wcontrol, and ΔVup is the acceleration amount ΔVup.

[0105] Therefore, when the downhill road condition C1 is satisfied while the distance between the current position Pn of the host vehicle 100 and the start point SLstart of the downhill road is sufficiently long, when the host vehicle 100 starts coasting now, at the timing when the own vehicle speed V becomes the lower limit vehicle speed Vlower when the host vehicle 100 reaches the start point SLstart of the downhill road, the appropriate deceleration amount condition C5 is satisfied.

[0106] In addition, the appropriate deceleration amount condition C5 is satisfied when the own vehicle speed V becomes a certain vehicle speed or higher, and moreover, the larger the acceleration amount ΔVup is, the earlier it is satisfied while the own vehicle speed V is small. Therefore, the appropriate deceleration amount condition C5 is a condition that is satisfied when the own vehicle speed V is less than the upper limit vehicle speed Vupper and equal to or higher than a predetermined vehicle speed Vth_2. The predetermined vehicle speed Vth_2 is a vehicle speed less than the upper limit vehicle speed Vupper and equal to or higher than the lower limit vehicle speed Vlower, and it can be said that the lower the vehicle speed is set, the larger the acceleration amount ΔVup (the acceleration amount of the own vehicle speed V while the host vehicle 100 is traveling on the downhill road SLdown).

[0107] Also, it can be said that the appropriate deceleration amount condition C5 is satisfied when the distance D1 before the downhill road becomes equal to or less than a predetermined distance Dth_2. In this case, the appropriate deceleration amount condition C5 is satisfied while the distance D1 before the downhill road is large, the larger the acceleration amount ΔVup is. Therefore, the appropriate deceleration amount condition C5 is a condition that is satisfied when the distance between the host vehicle 100 and the start point SLstart of the downhill road is equal to or less than the predetermined distance Dth_2. The predetermined distance Dth_2 can be said to be set to a longer distance, the larger the acceleration amount ΔVup (the acceleration amount of the own vehicle speed V while the host vehicle 100 is traveling on the downhill road SLdown).

[0108] Further, when the appropriate deceleration amount condition C5 is satisfied and the host vehicle 100 starts coasting, the host vehicle speed V reaches the lower limit vehicle speed Vlower when the host vehicle 100 reaches the downhill start point SLstart. Therefore, it can also be said that the appropriate deceleration amount condition C5 is a condition that is satisfied when, if the host vehicle 100 starts coasting at the current time, the host vehicle speed V reaches the lower limit vehicle speed Vlower when the host vehicle 100 reaches the downhill start point SLstart.

[0109] When the appropriate deceleration amount condition C5 is satisfied, the vehicle driving support device 10 determines "Yes" in step S535, advances the process to step S540, and stops the eco cruise control. Next, the vehicle driving support device 10 advances the process to step S545 and starts the forced coasting control. Next, the vehicle driving support device 10 advances the process to step S550, sets the value of the power running control execution flag Xpower to "0", and sets the value of the forced coasting control execution flag Xcoast to "1". Next, the vehicle driving support device 10 advances the process to step S595 and once terminates the process of this routine. As a result, since the forced coasting control is started, the host vehicle speed V decreases.

[0110] On the other hand, when the appropriate deceleration amount condition C5 is not satisfied, the vehicle driving support device 10 determines "No" in step S535, directly advances the process to step S595, and once terminates the process of this routine. In this case, the eco cruise control is continued.

[0111] Further, when the value of the forced coasting control execution flag Xcoast is "1" when the vehicle driving support device 10 executes the process of step S410 of the routine shown in FIG. 4, the vehicle driving support device 10 determines "No" in step S410 and directly advances the process to step S495 and once terminates the process of this routine. In this case, the forced coasting control is continued.

[0112] Further, when the downhill road condition C1 is not satisfied when the vehicle driving support device 10 executes the process of step S420, it is determined as "No" in step S420, the process directly proceeds to step S495, and the process of this routine is temporarily terminated. In this case, the eco cruise control is continued.

[0113] Further, when the preceding and following vehicle condition C2 is not satisfied when the vehicle driving support device 10 executes the process of step S425, it is determined as "No" in step S425, the process directly proceeds to step S495, and the process of this routine is temporarily terminated. In this case, the eco cruise control is continued.

[0114] Further, when the value of the power running control execution flag Xpower is "0" when the vehicle driving support device 10 executes the process of step S415, it is determined as "No" in step S415, the process proceeds to step S435, and the eco cruise control is executed. Next, the vehicle driving support device 10 proceeds the process to step S495, and temporarily terminates the process of this routine.

[0115] Further, when the execution of the eco cruise control is not required when the vehicle driving support device 10 executes the process of step S405, it is determined as "No" in step S405, the process proceeds to step S440, and when the eco cruise control is being executed, the eco cruise control is stopped. Next, the vehicle driving support device 10 proceeds the process to step S445, and when the forced coasting control is being executed, the forced coasting control is stopped. Next, the vehicle driving support device 10 proceeds the process to step S450, and sets the value of the forced coasting control execution flag Xcoast to "0". Next, the vehicle driving support device 10 proceeds the process to step S495, and temporarily terminates the process of this routine.

[0116] Furthermore, the vehicle driving support device 10 is configured to execute the routine shown in FIG. 6 at a predetermined calculation cycle. Therefore, at a predetermined timing, the vehicle driving support device 10 starts processing from step S600 of the routine shown in FIG. 6, advances the processing to step S605, and determines whether the value of the forced coasting control execution flag Xcoast is "1".

[0117] When the value of the forced coasting control execution flag Xcoast is "1", the vehicle driving support device 10 determines "Yes" at step S605, advances the processing to step S610, and determines whether the downhill road end condition C6 is satisfied. The downhill road end condition C6 is a condition that the host vehicle 100 has reached the downhill road end point SLend. The vehicle driving support device 10 determines whether the downhill road end condition C6 is satisfied based on the surrounding information IS.

[0118] When the downhill road end condition C6 is satisfied, the vehicle driving support device 10 determines "Yes" at step S610, advances the processing to step S615, and ends the forced coasting control. Next, the vehicle driving support device 10 advances the processing to step S620, sets the value of the power running control execution flag Xpower to "0". Next, the vehicle driving support device 10 advances the processing to step S625, and resumes the eco cruise control. Next, the vehicle driving support device 10 advances the processing to step S695, and temporarily ends the processing of this routine.

[0119] On the other hand, when the downhill road end condition C6 is not satisfied, the vehicle driving support device 10 determines "No" at step S610, advances the processing to step S630, and determines whether the host vehicle speed V is lower than the lower limit vehicle speed Vlower.

[0120] When the host vehicle speed V is lower than the lower limit vehicle speed Vlower, the vehicle driving support device 10 determines "Yes" at step S630, advances the processing to step S635, and issues a coasting continuation notification. Next, the vehicle driving support device 10 advances the processing to step S695, and temporarily ends the processing of this routine.

[0121] The coasting continuation notification is a notification for informing the driver to continue the coasting of the host vehicle 100 because there is a downhill road SLdown on the road where the host vehicle 100 is scheduled to travel. Therefore, in this case, after the coasting continuation notification is implemented, the forced coasting control is continued. That is, after the vehicle driving support device 10 starts coasting the host vehicle 100 when the high acceleration amount condition C4 (the third coasting permission condition) is satisfied, when the host vehicle speed V becomes lower than the lower limit vehicle speed Vlower, the driver is given a coasting continuation notification and the coasting of the host vehicle 100 is continued.

[0122] On the other hand, when the host vehicle speed V is equal to or higher than the lower limit vehicle speed Vlower, the vehicle driving support device 10 determines "No" in step S630, directly advances the process to step S695, and temporarily ends the process of this routine.

[0123] Also, when the value of the forced coasting control execution flag Xcoast is "0" when the vehicle driving support device 10 executes the process of step S605, the vehicle driving support device 10 determines "No" in step S605, directly advances the process to step S695, and temporarily ends the process of this routine.

[0124] The above is the operation of the vehicle driving support device 10.

[0125] According to this, in the scene where the process proceeds to step S525 of the routine shown in FIG. 5 and the forced coasting control is started, the host vehicle speed V changes as shown in FIG. 7, for example.

[0126] In the example shown in FIG. 7, since the road up to the downhill road start point SLstart is a flat road, the road gradient θ1 before the downhill road is zero. Also, since the road from the downhill road start point SLstart to the downhill road end point SLend is the downhill road SLdown, the downhill road gradient θ2 is a negative value. Also, since the road after the downhill road end point SLend is a flat road, the road gradient after the downhill road end point SLend is zero.

[0127] In the example shown in FIG. 7, when the host vehicle 100 reaches point P70, the high acceleration amount condition C4 is satisfied. Also, before the host vehicle 100 reaches point P70, the eco autonomous driving control is being executed. In the example shown in FIG. 7, before the host vehicle 100 reaches point P70, the power running control of the eco autonomous driving control is being executed. Therefore, the host vehicle speed V is increasing.

[0128] When the host vehicle 100 reaches point P70, the high acceleration amount condition C4 is satisfied and the forced coasting control is started. At this time, since the host vehicle 100 is traveling on a flat road, the host vehicle speed V begins to decrease.

[0129] After that, when the host vehicle 100 reaches point P71, since the host vehicle speed V falls below the lower limit vehicle speed Vlower, a coasting continuation notification is implemented.

[0130] After that, when the host vehicle 100 reaches the downhill road start point SLstart, the host vehicle speed V begins to increase. The host vehicle speed V increases until the host vehicle 100 reaches the downhill road end point SLend, and reaches the upper limit vehicle speed Vupper when the host vehicle 100 reaches the downhill road end point SLend.

[0131] When the host vehicle 100 reaches the downhill road end point SLend, the forced coasting control is terminated and the eco autonomous driving control is restarted. At this time, since the host vehicle speed V has reached the upper limit vehicle speed Vupper, the coasting control of the eco autonomous driving control is executed. And the road after the downhill road end point SLend is a flat road. Therefore, after the host vehicle 100 passes the downhill road end point SLend, the host vehicle speed V decreases.

[0132] According to this, when the high acceleration amount condition C4 is satisfied, even if the host vehicle speed V has not reached the upper limit vehicle speed Vupper, the coasting of the host vehicle 100 is started. For this reason, when the host vehicle 100 reaches the downhill road start point SLstart, the host vehicle speed V is sufficiently low. Therefore, while the host vehicle 100 is traveling on the downhill road SLdown, the host vehicle 100 can be coasted for a long distance. As a result, the amount of energy consumption can be reduced.

[0133] Furthermore, the host vehicle 100 can be coasted until it reaches the downhill road end point SLend. In addition, even after the host vehicle 100 passes the downhill road end point SLend, the host vehicle 100 can be coasted for a while. Therefore, the amount of energy consumption can be further reduced.

[0134] On the other hand, in a scenario where the process proceeds to step S545 of the routine shown in FIG. 5 and the forced coasting control is started, the host vehicle speed V changes as shown in FIG. 8, for example.

[0135] Also in the example shown in FIG. 8, since the road up to the downhill road start point SLstart is a flat road, the road gradient θ1 before the downhill road is zero. Also, since the road from the downhill road start point SLstart to the downhill road end point SLend is the downhill road SLdown, the downhill road gradient θ2 is a negative value. Also, since the road after the downhill road end point SLend is a flat road, the road gradient after the downhill road end point SLend is zero.

[0136] In the example shown in FIG. 8, the appropriate deceleration amount condition C5 is satisfied when the host vehicle 100 reaches the point P80. Also, before the host vehicle 100 reaches the point P80, the eco-driving control is being executed. In the example shown in FIG. 8, before the host vehicle 100 reaches the point P80, the power running control of the eco-driving control is being executed. Therefore, the host vehicle speed V is increasing.

[0137] When the host vehicle 100 reaches the point P80, the appropriate deceleration amount condition C5 is satisfied and the forced coasting control is started. At this time, since the host vehicle 100 is traveling on a flat road, the host vehicle 100 begins to decelerate.

[0138] After that, when the host vehicle 100 reaches the downhill road start point SLstart, the host vehicle speed V reaches the lower limit vehicle speed Vlower. Then, when the host vehicle 100 reaches the downhill road start point SLstart, the host vehicle 100 starts to ascend. The host vehicle speed V increases until the host vehicle 100 reaches the downhill road end point SLend.

[0139] When the host vehicle 100 reaches the downhill road end point SLend, the forced coasting control is terminated and the eco cruise control is resumed. At this time, since the host vehicle speed V has not reached the upper limit vehicle speed Vupper, the power running control of the eco cruise control is executed. Therefore, the host vehicle speed V increases, and when the host vehicle 100 reaches the point P81, the host vehicle speed V reaches the upper limit vehicle speed Vupper, and the coasting control of the eco cruise control is started, and the host vehicle speed V starts to decrease.

[0140] According to this, when the appropriate deceleration speed quantity condition C7 is satisfied, the coasting of the host vehicle 100 is started even if the host vehicle speed V has not reached the upper limit vehicle speed Vupper. For this reason, when the host vehicle 100 reaches the downhill road start point SLstart, the host vehicle speed V is sufficiently low. Therefore, while the host vehicle 100 is traveling on the downhill road SLdown, the host vehicle 100 can be coasted for a long distance. As a result, the amount of energy consumption can be reduced.

[0141] Note that the present invention is not limited to the above-described embodiment, and various modifications can be adopted within the scope of the present invention.

[0142] For example, the vehicle driving support device 10 may be configured to execute the routines shown in FIGS. 9 and 10. When a predetermined condition is satisfied, the vehicle driving support device 10 executes forced coasting control by executing the routines shown in FIGS. 9 and 10.

[0143] Therefore, at a predetermined timing, the vehicle driving support device 10 starts processing from step S900 of the routine shown in FIG. 9, advances the processing to step S905, and determines whether execution of the eco cruise control is requested.

[0144] When the execution of eco autonomous driving control is requested, the vehicle driving support device 10 determines "Yes" in step S905, advances the process to step S910, and determines whether the value of the forced coasting control execution flag Xcoast is "0".

[0145] When the value of the forced coasting control execution flag Xcoast is "0", the vehicle driving support device 10 determines "Yes" in step S910, advances the process to step S915, and determines whether the value of the power running control execution flag Xpower is "1".

[0146] When the value of the power running control execution flag Xpower is "1", the vehicle driving support device 10 determines "Yes" in step S915, advances the process to step S920, and determines whether the curve road condition C8 is satisfied.

[0147] The curve road condition C8 is a coasting permission condition (the fifth coasting permission condition) that the road at a predetermined distance (predetermined curve road determination distance DCth) ahead of the host vehicle 100 and on which the host vehicle 100 is scheduled to travel is a curve road CV. The vehicle driving support device 10 determines whether the curve road condition C8 is satisfied based on the road information IR and / or the surrounding information IS.

[0148] When the curve road condition C8 is satisfied, the vehicle driving support device 10 determines "Yes" in step S920, advances the process to step S925, and determines whether the front and rear vehicle condition C2 is satisfied.

[0149] When the front and rear vehicle condition C2 is satisfied, the vehicle driving support device 10 determines "Yes" in step S925, advances the process to step S930, and executes the routine shown in FIG. 10. Therefore, when the vehicle driving support device 10 advances the process to step S925, it starts the process from step S1000 of the routine shown in FIG. 10, advances the process to step S1005, and acquires the deceleration amount ΔVdown.

[0150] The deceleration amount ΔVdown is the amount by which the vehicle speed V decreases until the host vehicle 100 reaches the start point CVstart of the curve road (the point where the curve road CV begins) when the host vehicle 100 starts coasting now. In this example, the vehicle driving support device 10 acquires the deceleration amount ΔVdown according to the above formula 1.

[0151] Next, the vehicle driving support device 10 proceeds to step S1010 in the process and determines whether or not the specified deceleration amount condition C9 is satisfied.

[0152] The specified deceleration amount condition C9 is a coasting permission condition (the sixth coasting permission condition) that when the host vehicle 100 starts coasting and travels to the start point CVstart of the curve road while coasting, the vehicle speed V of the host vehicle 100 becomes the recommended vehicle speed Vrec when it reaches the start point CVstart of the curve road. That is, the specified deceleration amount condition C9 is satisfied when the following formula 10 holds.

[0153] V - |ΔVdown| = Vrec …(10)

[0154] In the above formula 10, V is the vehicle speed V, ΔVdown is the deceleration amount ΔVdown, and Vrec is the recommended vehicle speed Vrec.

[0155] The recommended vehicle speed Vrec is the vehicle speed recommended as the vehicle speed when the host vehicle 100 travels on the curve road CV that is a predetermined curve road determination distance DCth ahead of the host vehicle 100 and on which the host vehicle 100 is scheduled to travel.

[0156] When the specified deceleration amount condition C9 is satisfied, the vehicle driving support device 10 determines "Yes" in step S1010, advances the process to step S1015, and stops the eco cruise control. Next, the vehicle driving support device 10 advances the process to step S1020 and starts the forced coasting control. Next, the vehicle driving support device 10 advances the process to step S1025, sets the value of the power running control execution flag Xpower to "0", and sets the value of the forced coasting control execution flag Xcoast to "1". Next, the vehicle driving support device 10 advances the process to step S1095 and temporarily ends the process of this routine. As a result, since the forced coasting control is started, the own vehicle speed V decreases.

[0157] On the other hand, when the specified deceleration amount condition C9 is not satisfied, the vehicle driving support device 10 determines "No" in step S1010, directly advances the process to step S1095, and temporarily ends the process of this routine. In this case, the eco cruise control is continued.

[0158] Also, when the value of the forced coasting control execution flag Xcoast is "1" when the vehicle driving support device 10 executes the process of step S910 of the routine shown in FIG. 9, the vehicle driving support device 10 determines "No" in step S910 and directly advances the process to step S995, and temporarily ends the process of this routine. In this case, the forced coasting control is continued.

[0159] Also, when the curve road condition C8 is not satisfied when the vehicle driving support device 10 executes the process of step S920, the vehicle driving support device 10 determines "No" in step S920 and directly advances the process to step S995, and temporarily ends the process of this routine. In this case, the eco cruise control is continued.

[0160] Also, when the preceding and following vehicle condition C2 is not satisfied when the vehicle driving support device 10 executes the process of step S925, the vehicle driving support device 10 determines "No" in step S925 and directly advances the process to step S995, and temporarily ends the process of this routine. In this case, the eco cruise control is continued.

[0161] Further, when the value of the power running control execution flag Xpower is "0" when the vehicle driving support device 10 executes the process of step S915, the vehicle driving support device 10 determines "No" in step S915, advances the process to step S935, and executes the eco autonomous driving control. Next, the vehicle driving support device 10 advances the process to step S995 and temporarily ends the process of this routine.

[0162] Further, when the execution of the eco autonomous driving control is not required when the vehicle driving support device 10 executes the process of step S905, the vehicle driving support device 10 determines "No" in step S905, advances the process to step S940, and stops the eco autonomous driving control if it is being executed. Next, the vehicle driving support device 10 advances the process to step S945 and stops the forced coasting control if it is being executed. Next, the vehicle driving support device 10 advances the process to step S950 and sets the value of the forced coasting control execution flag Xcoast to "0". Next, the vehicle driving support device 10 advances the process to step S995 and temporarily ends the process of this routine.

[0163] Further, the vehicle driving support device 10 is configured to execute the routine shown in FIG. 11 at a predetermined calculation cycle. Therefore, at a predetermined timing, the vehicle driving support device 10 starts the process from step S1100 of the routine shown in FIG. 11, advances the process to step S1105, and determines whether the value of the forced coasting control execution flag Xcoast is "1".

[0164] When the value of the forced coasting control execution flag Xcoast is "1", the vehicle driving support device 10 determines "Yes" in step S1105, advances the process to step S1110, and determines whether the curve road start condition C10 is satisfied. The curve road start condition C10 is a condition that the host vehicle 100 has reached the curve road start point CVstart. The vehicle driving support device 10 determines whether the curve road start condition C10 is satisfied based on the surrounding information IS and / or the road information IR.

[0165] When the curve road start condition C10 is satisfied, the vehicle driving support device 10 determines "Yes" in step S1110, advances the process to step S1115, and ends the forced coasting control. Next, the vehicle driving support device 10 advances the process to step S1120, and sets the value of the forced coasting control execution flag Xcoast to "0". Next, the vehicle driving support device 10 advances the process to step S1125, and resumes the eco-driving autonomous control. Next, the vehicle driving support device 10 advances the process to step S1195, and once ends the process of this routine.

[0166] On the other hand, when the curve road start condition C10 is not satisfied, the vehicle driving support device 10 determines "No" in step S1110, directly advances the process to step S1195, and once ends the process of this routine.

[0167] Also, when the value of the forced coasting control execution flag Xcoast is "0" at the time when the vehicle driving support device 10 executes the process of step S1105, the vehicle driving support device 10 determines "No" in step S1105, directly advances the process to step S1195, and once ends the process of this routine.

[0168] According to this, when the specified deceleration amount condition C9 is satisfied, even if the host vehicle 100 has not reached the upper limit vehicle speed Vupper, the coasting of the host vehicle 100 is started, and the host vehicle 100 can be coasted until the host vehicle 100 reaches the curve road start point CVstart. For this reason, the amount of energy consumption can be reduced.

Explanation of Signs

[0169] 10…Vehicle driving support device, 20…Drive device, 30…Brake device, 41…Eco-driving support request operator, 42…Eco-level setting operator, 50…Vehicle speed detection device, 60…Surrounding information acquisition device, 70…Road information acquisition device, 90…ECU, 100…Host vehicle, 200…Leading vehicle, 300…Following vehicle

Claims

1. A control device that executes autonomous driving control to autonomously drive the host vehicle while increasing and decreasing the vehicle speed of the host vehicle between an upper limit vehicle speed and a lower limit vehicle speed, wherein, when the vehicle speed rises and reaches the upper limit vehicle speed during the execution of the autonomous driving control, the control device causes the host vehicle to coast, and when the vehicle speed drops and reaches the lower limit vehicle speed, the control device causes the host vehicle to accelerate. In a vehicle driving support device, when the coasting permission condition is satisfied while the control device is causing the host vehicle to accelerate during the execution of the autonomous driving control, the control device is configured to cause the host vehicle to coast even if the vehicle speed of the host vehicle is lower than the upper limit vehicle speed. The coasting permission condition is a condition that a road a predetermined distance ahead of the host vehicle and on which the host vehicle is scheduled to travel is a downhill road. Vehicle driving support device.

2. In the vehicle driving support device according to claim 1, the coasting permission condition includes a condition that the vehicle speed is less than the upper limit vehicle speed and equal to or higher than a predetermined vehicle speed, wherein the predetermined vehicle speed is a vehicle speed that is less than the upper limit vehicle speed and equal to or higher than the lower limit vehicle speed, and is set to a lower vehicle speed as the amount of increase in the vehicle speed while the host vehicle is traveling on the downhill road is larger. Vehicle driving support device.

3. In the vehicle driving support device according to claim 1, the coasting permission condition includes a condition that the vehicle speed is less than the upper limit vehicle speed and equal to or higher than a predetermined vehicle speed, wherein the predetermined vehicle speed is a vehicle speed that is less than the upper limit vehicle speed, and is set to a lower vehicle speed as the amount of increase in the vehicle speed while the host vehicle is traveling on the downhill road is larger. Vehicle driving support device.

4. In the vehicle driving support device according to claim 1, the coasting permission condition includes a condition that the distance between the host vehicle and the start point of the downhill road is equal to or less than a predetermined distance, wherein the predetermined distance is set to a longer distance as the amount of increase in the vehicle speed while the host vehicle is traveling on the downhill road is larger. Vehicle driving support device.

5. In the vehicle driving support device according to claim 1, the coasting permission condition includes a condition that when the host vehicle starts to coast at the current time, the vehicle speed reaches the lower limit vehicle speed when the host vehicle reaches the start point of the downhill road. Vehicle driving support device.

6. In the vehicle driving support device according to claim 1, The coasting permission condition is a condition that is also satisfied when there is no following vehicle and the speed increase amount of the host vehicle while traveling on the downhill road is equal to or greater than the difference between the upper limit vehicle speed and the lower limit vehicle speed. After the coasting permission condition is satisfied and the host vehicle starts coasting, when the vehicle speed becomes lower than the lower limit vehicle speed, the control device is configured to notify the user of the host vehicle to continue coasting and to continue coasting the host vehicle. The coasting continuation notification is a notification for informing the user to continue coasting the host vehicle because there is a downhill road on the road on which the host vehicle is scheduled to travel. Vehicle driving support device.

Images