Vehicle driving assistance system

Abstract

The present invention provides a vehicle driving assistance system that enables the vehicle to coast appropriately when traveling on public roads. [Solution] The vehicle driving support device 10 performs autonomous driving control, which allows the vehicle to drive autonomously by alternately switching between power control, which powers the vehicle 100, and coasting control, which allows the vehicle to coast. The vehicle driving support device switches between power control and coasting control so that the vehicle's speed or the distance between the vehicle and the preceding vehicle 200 falls within a predetermined range of speed or distance. When the road the vehicle is traveling on is a public road, the vehicle driving support device narrows the predetermined range compared to when the road the vehicle is traveling on is a highway or an expressway.

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 traveling control for causing the own vehicle to travel autonomously by powering or coasting the own vehicle. As such a conventional vehicle driving support device, there is also known a vehicle driving support device configured to prohibit coasting of the own vehicle under autonomous traveling control when the own vehicle travels on a curved road or a general road (see, for example, Patent Document 1). That is, there is known a vehicle driving support device configured to prohibit coasting of the own vehicle under autonomous traveling control in situations where it is determined that coasting the own vehicle may cause danger. [Prior Art Literature] [Patent Literature]

[0003] [Patent Document 1] Japanese Unexamined Patent Publication No. 2018-122818 [Summary of the Invention]

[0004] As described above, conventional vehicle driving support devices prohibit coasting of the own vehicle under autonomous traveling control when the own vehicle travels on a general road, because performing such coasting may cause danger. However, even when the own vehicle travels on a general road, coasting of the own vehicle under autonomous traveling control does not necessarily cause danger. That is, even if the own vehicle is traveling on a general road, it is not necessary to prohibit coasting of the own vehicle under autonomous traveling control. If coasting of the own vehicle is prohibited in such situations, the opportunity to reduce the energy used for traveling the own vehicle is lost.

[0005] An object of the present invention is to provide a vehicle driving support device that can appropriately coast the own vehicle when the own vehicle is traveling on a general road.

[0006] The vehicle driving assistance device according to the present invention includes a control device that performs autonomous driving control, which causes the vehicle to drive autonomously while alternately switching between power control, which causes the vehicle to accelerate, and coasting control, which causes the vehicle to coast. The control device switches between power control and coasting control so that the vehicle's speed or the distance between the vehicle and the preceding vehicle falls within a predetermined range of speed or distance. Furthermore, the control device narrows the predetermined range when the vehicle is traveling on a public road compared to when the vehicle is traveling on a highway or expressway.

[0007] According to the present invention, when the vehicle is traveling on a public road, the predetermined range is made relatively narrow. Therefore, when the vehicle is coasted by autonomous driving control, it is suppressed that the vehicle's speed becomes excessively low or that the increase or decrease in the vehicle's speed becomes excessively large. As a result, the vehicle can coast appropriately when traveling on a public road.

[0008] Furthermore, in the vehicle driving support device according to the present invention, the control device may be configured not to perform coasting control if the deceleration of the vehicle due to the execution of coasting control is greater than a predetermined deceleration threshold.

[0009] If a vehicle's deceleration is high, it may inconvenience drivers of other vehicles in the vicinity, such as following vehicles. According to the present invention, if the vehicle's deceleration is greater than a predetermined deceleration threshold, coasting control is not performed. Therefore, it is possible to suppress the inconvenience caused by the vehicle to drivers of other vehicles.

[0010] Furthermore, if the vehicle's deceleration is large, shortly after the start of coasting control, the vehicle's speed will reach the lower limit of a predetermined range, or the distance between the vehicle and the preceding vehicle will reach the upper limit of a predetermined range, and the system will immediately switch to power control. As a result, the effect of improving the energy efficiency of the vehicle's movement will decrease. In addition, ride comfort will also deteriorate. According to the present invention, if the vehicle's deceleration is greater than a predetermined deceleration, coasting control will not be performed. Therefore, the effect of improving the energy efficiency of the vehicle's movement can be maintained overall, and deterioration of ride comfort can be suppressed.

[0011] Furthermore, in the vehicle driving assistance device according to the present invention, the control device may be configured to set the predetermined deceleration threshold to a smaller value when the road on which the vehicle is traveling is a general road compared to when the road on which the vehicle is traveling is a highway or an expressway.

[0012] When a vehicle is traveling on a public road, a large deceleration can increase the likelihood of causing inconvenience to drivers of other vehicles around it, such as following vehicles. According to the present invention, when a vehicle is traveling on a public road, the predetermined deceleration threshold is reduced. Therefore, it is possible to suppress the inconvenience caused to drivers of other vehicles when a vehicle is traveling on a public road.

[0013] Furthermore, when a vehicle is traveling on an ordinary road, its speed is generally relatively low. Therefore, the deceleration of the vehicle due to coasting control is relatively small. However, when a vehicle is traveling on an ordinary road, even if the deceleration of the vehicle due to coasting control is relatively small, the vehicle's speed will reach the lower limit of a predetermined range or the distance between the vehicle and the preceding vehicle will reach the upper limit of a predetermined range in a short time after the start of coasting control, and the system will immediately switch to power control. As a result, the effect of improving the energy efficiency of the vehicle's driving is reduced. Also, the ride comfort deteriorates. According to the present invention, when a vehicle is traveling on an ordinary road, the predetermined deceleration threshold is reduced. Therefore, when a vehicle is traveling on an ordinary road, coasting control is not performed even if the vehicle's deceleration is relatively large. As a result, the effect of improving the energy efficiency of the vehicle's driving can be maintained overall, and the deterioration of ride comfort can be suppressed.

[0014] Furthermore, in the vehicle driving support device according to the present invention, the control device may be configured to predict the deceleration of the vehicle when the power control is switched to coasting control while the power control is being executed, and to set a predetermined deceleration threshold to a smaller value when the road on which the vehicle is traveling is a general road compared to when the road on which the vehicle is traveling is a highway or an expressway, and to permit switching the power control to coasting control when the predicted deceleration is less than or equal to the predetermined deceleration threshold, and to prohibit switching the power control to coasting control when the predicted deceleration is greater than the predetermined deceleration threshold.

[0015] According to the present invention, when coasting control is not being performed, the deceleration of the vehicle if coasting control were performed is predicted, and a decision is made on whether or not to prohibit the performance of coasting control based on the predicted deceleration. Therefore, it is possible to more appropriately suppress the inconvenience caused to drivers of other vehicles when the vehicle is traveling on a public road.

[0016] Furthermore, as mentioned above, when a vehicle is traveling on an ordinary road, its speed is generally relatively low. Therefore, the deceleration of the vehicle due to coasting control is relatively small. However, when a vehicle is traveling on an ordinary road, even if the deceleration of the vehicle due to coasting control is relatively small, the vehicle's speed will reach the lower limit of a predetermined range or the distance between the vehicle and the preceding vehicle will reach the upper limit of a predetermined range in a short time after the start of coasting control, and the system will immediately switch to power control. As a result, the effect of improving the energy efficiency of the vehicle's driving is reduced. In addition, the ride comfort is also worsened. According to the present invention, when a vehicle is traveling on an ordinary road, the predetermined deceleration threshold is made smaller compared to when the vehicle is traveling on an expressway or motorway. Therefore, when a vehicle is traveling on an ordinary road, coasting control is not performed if the vehicle's deceleration is relatively large. As a result, the effect of improving the energy efficiency of the vehicle's driving can be maintained overall, and the deterioration of ride comfort can be suppressed.

[0017] In the vehicle driving support device according to the present invention, the control device may be configured to set a predetermined deceleration threshold to a smaller value when the road on which the vehicle is traveling is a general road compared to when the road on which the vehicle is traveling is a highway or an expressway, and to stop the coasting control if the deceleration of the vehicle becomes greater than the predetermined deceleration threshold during the execution of the coasting control.

[0018] According to the present invention, when coasting control is being performed, the deceleration of the vehicle when coasting control is initiated is predicted, and a decision is made on whether or not to prohibit the execution of coasting control based on the predicted deceleration. Therefore, it is possible to more appropriately suppress the inconvenience caused to drivers of other vehicles when the vehicle is traveling on a public road.

[0019] Furthermore, as mentioned above, when a vehicle is traveling on an ordinary road, its speed is generally relatively low. Therefore, the deceleration of the vehicle due to coasting control is relatively small. However, when a vehicle is traveling on an ordinary road, even if the deceleration of the vehicle due to coasting control is relatively small, the vehicle's speed will reach the lower limit of a predetermined range or the distance between the vehicle and the preceding vehicle will reach the upper limit of a predetermined range in a short time after the start of coasting control, and the system will immediately switch to power control. As a result, the effect of improving the energy efficiency of the vehicle's driving is reduced. In addition, the ride comfort is also worsened. According to the present invention, when a vehicle is traveling on an ordinary road, the predetermined deceleration threshold is made smaller compared to when the vehicle is traveling on an expressway or motorway. Therefore, when a vehicle is traveling on an ordinary road, coasting control is not performed if the vehicle's deceleration is relatively large. As a result, the effect of improving the energy efficiency of the vehicle's driving can be maintained overall, and the deterioration of ride comfort can be suppressed.

[0020] The components of the present invention are not limited to the embodiments described below with reference to the drawings. Other objects, features, and incidental advantages of the present invention will be readily apparent from the description of the embodiments. [Brief explanation of the drawing]

[0021] [Figure 1] Figure 1 is a diagram showing a vehicle driving assistance device according to an embodiment of the present invention. [Figure 2] Figure 2 shows the vehicle in front. [Figure 3] Figure 3 is a flowchart showing the routine executed by a vehicle driving assistance device according to an embodiment of the present invention. [Figure 4] Figure 4 is a flowchart showing the routine executed by a vehicle driving assistance device according to an embodiment of the present invention. [Modes for carrying out the invention]

[0022] Hereinafter, a vehicle driving support apparatus according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows a vehicle driving support apparatus 10 according to an embodiment of the present invention. The vehicle driving support apparatus 10 is mounted on a host vehicle 100. Hereinafter, the vehicle driving support apparatus 10 will be described by taking, as an example, a case where the operator or user of the host vehicle 100 is a driver of the host vehicle 100 (that is, a person who rides in the host vehicle 100 and drives the host vehicle 100). However, the operator or user of the host vehicle 100 may be a remote operator of the host vehicle 100 (that is, a person who remotely drives the host vehicle 100 without riding in the host vehicle 100). In the following description, the driver of the host vehicle 100 may be simply referred to as "driver".

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

[0024] In this example, the vehicle driving support apparatus 10 includes only one ECU 90, but it may be configured to include a plurality of ECUs such that each ECU shares the functions of the vehicle driving support apparatus 10 described below.

[0025] Further, the vehicle driving support apparatus 10 may be configured such that a program stored in a storage medium can be updated via wireless communication (e.g., Internet communication) with an external device.

[0026] Furthermore, the vehicle driving assistance system 10 can be applied not only to vehicles driven by manual operation by an operator, but also to vehicles driven by automated driving.

[0027] As shown in Figure 1, the vehicle 100 is equipped with a drive unit 20, a braking unit 30, and a power transmission unit 40.

[0028] The drive unit 20 is a device that generates the driving force supplied to the vehicle 100 (particularly to the drive wheels of the vehicle 100). In this example, the drive unit 20 comprises an internal combustion engine 21 and an electric motor 22. The drive unit 20 is electrically connected to the ECU 90. The vehicle driving support device 10 can control the driving force supplied to the vehicle 100 by controlling the operation of the drive unit 20 (i.e., the internal combustion engine 21 and the electric motor 22).

[0029] The braking device 30 is a device that applies braking force to the vehicle 100 (particularly to the wheels of the vehicle 100). In this example, the braking device 30 includes a hydraulic brake system 31. The braking device 30 is electrically connected to the ECU 90. The vehicle driving support system 10 can control the braking force applied to the vehicle 100 by controlling the operation of the braking device 30 (more specifically, the operation of the hydraulic brake system 31).

[0030] The power transmission device 40 is a device that transmits the power output from the drive unit 20 to the drive wheels of the vehicle 100. The power transmission device 40 is, for example, a transmission. The power transmission device 40 is electrically connected to the ECU 90. The vehicle driving support device 10 can establish a power transmission path and transmit the power output from the drive unit 20 to the drive wheels of the vehicle 100 by controlling the operation of the power transmission device 40. The power transmission path is the path that transmits power from the drive unit 20 to the drive wheels of the vehicle 100. The vehicle driving support device 10 can also block the power transmission path by controlling the operation of the power transmission device 40, preventing power from being transmitted from the drive unit 20 to the drive wheels of the vehicle 100.

[0031] Furthermore, the vehicle 100 is equipped with an autonomous driving control controller 51, a vehicle speed setting controller 52, a vehicle speed control width setting controller 53, a vehicle distance setting controller 54, a vehicle distance control width setting controller 55, a vehicle speed detection device 61, an acceleration sensor 62, a gradient sensor 63, a surrounding information acquisition device 70, a GPS signal receiver 81, and a map database 82.

[0032] The autonomous driving control controller 51 is a device operated by the driver. By operating the autonomous driving control controller 51, the driver can request the execution or cessation of autonomous driving control, as described later. The autonomous driving control controller 51 is electrically connected to the ECU 90. When the autonomous driving control controller 51 is operated while autonomous driving control is not being performed, the vehicle driving support system 10 determines that the execution of autonomous driving control has been requested. On the other hand, when the autonomous driving control controller 51 is operated while autonomous driving control is being performed, the vehicle driving support system 10 determines that the cessation of autonomous driving control has been requested.

[0033] The vehicle speed setting device 52 is a device operated by the driver. By operating the vehicle speed setting device 52, the driver can set the target vehicle speed Vset, which will be used for autonomous driving control described later. The target vehicle speed Vset is the speed set by the driver as the target value of the vehicle speed V1. The vehicle speed V1 is the driving speed of the vehicle 100.

[0034] The vehicle speed control width setting device 53 is a device operated by the driver. By operating the vehicle speed control width setting device 53, the driver can set the set vehicle speed control width WVset. The set vehicle speed control width WVset is used to set the target vehicle speed control width WVtgt, which is used for autonomous driving control, as described later.

[0035] The inter-vehicle distance setting device 54 is a device operated by the driver. By operating the inter-vehicle distance setting device 54, the driver can set the set inter-vehicle distance Dset, which will be used for autonomous driving control described later.

[0036] In this example, the driver can set the set following distance Dset to one of the following distances: a long distance, a medium distance, or a short distance, by operating the following distance setting device 54. If a long distance is set as the set following distance Dset, the relatively long distance Dlong will be set as the set following distance Dset. If a medium distance is set as the set following distance Dset, the medium distance Dmid will be set as the set following distance Dset. If a short distance is set as the set following distance Dset, the relatively short distance Dshort will be set as the set following distance Dset.

[0037] The set following distance Dset is set to a longer distance the higher the vehicle speed V1 is. However, if the vehicle speed V1 is the same, the relatively long distance Dlong is longer than the medium distance Dmid. Also, if the vehicle speed V1 is the same, the medium distance Dmid is longer than the relatively short distance Dshort.

[0038] The inter-vehicle distance control width setting device 55 is a device operated by the driver. By operating the inter-vehicle distance control width setting device 55, the driver can set the set inter-vehicle distance control width WDset. The set inter-vehicle distance control width WDset is used to set the target inter-vehicle distance control width WDtgt, which is used in the autonomous driving control described later.

[0039] The vehicle speed detection device 61 is a device for detecting the vehicle speed V1. The vehicle speed detection device 61 is equipped with, for example, wheel speed sensors provided on each wheel of the vehicle 100. The vehicle speed detection device 61 is electrically connected to the ECU 90. The vehicle driving support system 10 acquires the vehicle speed V1 using the vehicle speed detection device 61.

[0040] The acceleration sensor 62 is a device for detecting acceleration G. Acceleration G is the acceleration of the vehicle 100 in the longitudinal direction. The acceleration sensor 62 is electrically connected to the ECU 90. The vehicle driving assistance system 10 acquires acceleration G using the acceleration sensor 62.

[0041] The gradient sensor 63 is a device for detecting the road gradient θ. The road gradient θ is the gradient of the road on which the vehicle 100 is currently traveling. The gradient sensor 63 is electrically connected to the ECU 90. The vehicle driving assistance system 10 acquires the road gradient θ using the gradient sensor 63.

[0042] The surrounding information acquisition device 70 is a device for detecting information about the surroundings of the vehicle 100. In this example, the surrounding information acquisition device 70 is equipped with a plurality of electromagnetic wave sensors 71 and a plurality of image sensors 72.

[0043] The electromagnetic wave sensor 71 is electrically connected to the ECU 90. The electromagnetic wave sensor 71 is, for example, a radar sensor such as a millimeter-wave radar. The vehicle driving assistance system 10 acquires information (object information IO) related to objects present around its own vehicle 100 as surrounding information IS using the electromagnetic wave sensor 71. In particular, the object information IO includes information about the preceding vehicle 200.

[0044] As shown in Figure 2, the preceding vehicle 200 is another vehicle that is traveling in the same lane LN1 ahead of the vehicle 100 and within a predetermined distance Dth ahead of the vehicle 100. The same lane LN1 is the lane in which the vehicle 100 is traveling. The preceding vehicle 200 is detected based on surrounding information IS.

[0045] The image sensor 72 is electrically connected to the ECU 90. The image sensor 72 is, for example, a camera sensor. The vehicle driving assistance system 10 acquires image information ICs related to the surroundings of its own vehicle 100 as surrounding information IS using the image sensor 72. In particular, the image information ICs include information about the preceding vehicle 200.

[0046] The GPS signal receiver 81 is a device that receives GPS signals. The GPS signal receiver 81 is electrically connected to the ECU 90. The vehicle driving assistance system 10 receives GPS signals via the GPS signal receiver 81. The vehicle driving assistance system 10 obtains the current position of its own vehicle 100 based on the GPS signals.

[0047] The map database 82 is a device that stores map information IM. The map database 82 is electrically connected to the ECU 90. The vehicle driving assistance system 10 obtains road information IR from the current position of the vehicle 100 and the map information IM. The road information IR is information about the road on which the vehicle 100 is traveling. In particular, the road information IR includes information on whether the road on which the vehicle 100 is traveling is an expressway or an expressway or an ordinary road.

[0048] <Operation of vehicle driver assistance system> Next, the operation of the vehicle driving assistance system 10 will be explained.

[0049] The vehicle driving support device 10 executes the routines shown in Figures 3 to 5 at predetermined time intervals, and when predetermined conditions are met, it performs autonomous driving control. Autonomous driving control is a control that makes the vehicle 100 move autonomously by switching between power control and coasting control.

[0050] Power control is a control method that enables the vehicle 100 to exert power. When power control is performed, the vehicle driving support device 10 enables the vehicle 100 to exert power by applying driving force from the drive unit 20 to the vehicle 100. Alternatively, optimal power control may be used as the power control method. Optimal power control is a control method that enables the vehicle 100 to exert power by applying driving force from the drive unit 20 to the vehicle 100 while controlling the operation of the drive unit 20 to maximize the driving energy efficiency. Driving energy efficiency is the energy efficiency when the drive unit 20 generates driving force.

[0051] In this example, the vehicle driving support device 10, in principle, controls the operation of the drive unit 20 so that the vehicle 100 accelerates when power control is performed.

[0052] Coasting control is a control method that allows the vehicle 100 to coast. When coasting control is performed, the vehicle driving support device 10 allows the vehicle 100 to coast by stopping the application of driving force from the drive unit 20 to the vehicle 100. In this example, when coasting control is performed, the vehicle driving support device 10 stops the application of driving force from the drive unit 20 to the vehicle 100 by disconnecting the driving force transmission path. As described above, the driving force transmission path is the path through which driving force is applied from the drive unit 20 to the vehicle 100. The vehicle driving support device 10 disconnects the driving force transmission path by controlling the operation of the driving force transmission device 40.

[0053] In this manner, the vehicle driving support device 10 performs autonomous driving control, which involves alternately switching between power control to propel the vehicle 100 and coasting control to allow the vehicle 100 to coast.

[0054] Furthermore, autonomous driving control includes autonomous vehicle speed control and autonomous inter-vehicle distance control.

[0055] As shown in Figure 2, the vehicle driving support system 10 performs autonomous inter-vehicle distance control as autonomous driving control when a preceding vehicle 200 is present. On the other hand, when there is no preceding vehicle 200, the vehicle driving support system 10 performs autonomous vehicle speed control as autonomous driving control.

[0056] Autonomous vehicle speed control is a control system that allows the vehicle 100 to move autonomously by repeatedly and alternately performing power control and coasting control so that the vehicle speed V1 is maintained within the target vehicle speed range RVtgt.

[0057] When the vehicle driving support system 10 is performing autonomous vehicle speed control, if the vehicle speed V1 increases due to the execution of power control and reaches the target upper limit speed Vtgt_max, it terminates power control and starts coasting control. The target upper limit speed Vtgt_max is the upper limit of the target vehicle speed range RVtgt. In this example, the set vehicle speed Vset is set as the target upper limit speed Vtgt_max (Vtgt_max = Vset).

[0058] On the other hand, when the vehicle driving support device 10 is performing autonomous vehicle speed control, if the vehicle speed V1 decreases due to the execution of coasting control and reaches the target lower limit speed Vtgt_min, it terminates coasting control and starts power control. The target lower limit speed Vtgt_min is the lower limit of the target vehicle speed range RVtgt. The target lower limit speed Vtgt_min is the speed obtained by subtracting the target vehicle speed control width WVtgt from the set vehicle speed Vset.

[0059] In this manner, the vehicle driving support system 10 switches between power control and coasting control so that the vehicle speed V1 falls within the target vehicle speed range RVtgt.

[0060] Autonomous inter-vehicle distance control is a control system that autonomously drives the vehicle 100 by repeatedly and autonomously performing power control and coasting control alternately so that the inter-vehicle distance D is maintained within the target inter-vehicle distance range RDtgt. The inter-vehicle distance D is the distance between the vehicle 100 and the preceding vehicle 200. The inter-vehicle distance D is obtained based on surrounding information IS.

[0061] When the vehicle driving support system 10 is performing autonomous inter-vehicle distance control, if the inter-vehicle distance D is shortened by the execution of power control and reaches the target lower limit inter-vehicle distance Dtgt_min, it terminates power control and starts coasting control. The target lower limit inter-vehicle distance Dtgt_min is the lower limit of the target inter-vehicle distance range RDtgt. In this example, the set inter-vehicle distance Dset is set as the target lower limit inter-vehicle distance Dtgt_min (Dtgt_min = Dset).

[0062] On the other hand, when the vehicle driving support system 10 is performing autonomous inter-vehicle distance control, if the inter-vehicle distance D increases due to the execution of coasting control and reaches the target upper limit inter-vehicle distance Dtgt_max, it terminates coasting control and starts power control. The target upper limit inter-vehicle distance Dtgt_max is the upper limit of the target inter-vehicle distance range RDtgt. In this example, the target upper limit inter-vehicle distance Dtgt_max is set as the value obtained by adding the target lower limit inter-vehicle distance Dtgt_min to the target inter-vehicle distance control width WDtgt (Dtgt_max = Dtgt_min + WDtgt).

[0063] In this way, the vehicle driving support system 10 switches between power control and coasting control so that the distance D between vehicles falls within the target distance range RDtgt.

[0064] Furthermore, during power control, if the vehicle speed V1 reaches the target upper limit speed Vtgt_max before the inter-vehicle distance D reaches the target lower limit inter-vehicle distance Dtgt_min, power maintenance control is continued to maintain the vehicle speed V1 at the target upper limit speed Vtgt_max. Also, during coasting control, if the vehicle speed V1 reaches the target lower limit speed Vtgt_min before the inter-vehicle distance D reaches the target upper limit inter-vehicle distance Dtgt_max, coasting control is terminated, and power control is performed to maintain the vehicle speed V1 at the target lower limit speed Vtgt_min.

[0065] Therefore, autonomous inter-vehicle distance control can also be described as a control method that allows the vehicle 100 to move autonomously by repeatedly and alternately executing power control and coasting control so that the vehicle speed V1 is maintained within the range between the target upper speed limit Vtgt_max and the target lower speed limit Vtgt_min.

[0066] When a predetermined timing occurs, the vehicle driving support system 10 starts processing from step S300 of the routine shown in Figure 3. Then, the vehicle driving support system 10 proceeds to step S305 and determines whether or not the execution request condition C1 is met.

[0067] Execution request condition C1 is met when the execution of autonomous driving control is requested.

[0068] If the execution request condition C1 is met, the vehicle driving support device 10 determines "Yes" in step S305 and proceeds to step S310 to determine whether or not power control is being performed.

[0069] If power control is being performed, the vehicle driving support device 10 determines "Yes" in step S310 and proceeds to step S315 to determine whether the coasting start condition C2 has been met.

[0070] Coasting initiation condition C2 is met when the vehicle speed V1 increases and reaches the target upper limit speed Vtgt_max, if there is no preceding vehicle 200. On the other hand, if there is a preceding vehicle 200, coasting initiation condition C2 is met when the distance between vehicles D decreases and reaches the target lower limit distance between vehicles Dtgt_min.

[0071] If coasting start condition C2 is not met, the vehicle driving support system 10 determines "No" in step S315 and proceeds directly to step S395, terminating the processing of this routine. In this case, power control continues. On the other hand, if coasting start condition C2 is met, the vehicle driving support system 10 determines "Yes" in step S315 and proceeds to step S320, where it determines whether coasting permission condition C3 is met.

[0072] Coasting permission condition C3 is met when power control is being performed, and the predicted deceleration Gd_p is less than or equal to a predetermined deceleration threshold Gd_th. On the other hand, coasting permission condition C3 is met when coasting control is being performed, and the detected deceleration Gd_d is less than or equal to a predetermined deceleration threshold Gd_th.

[0073] The predicted deceleration Gd_p is the predicted deceleration of the vehicle 100 that would occur if the power control were switched to coasting control at this time. The vehicle driving support system 10 predicts the deceleration of the vehicle 100 based on the current vehicle speed V1 and road gradient θ, etc., and acquires the predicted deceleration as the predicted deceleration Gd_p. In this way, the vehicle driving support system 10 predicts the deceleration of the vehicle 100 that would occur if the power control were switched to coasting control while power control is being performed.

[0074] Furthermore, the detected deceleration Gd_d is the current deceleration of the vehicle 100. When the acceleration G detected by the acceleration sensor 62 is less than zero, the vehicle driving support system 10 obtains the absolute value of the detected acceleration G as the detected deceleration Gd_d.

[0075] At the point when the vehicle driving support device 10 proceeds to step S320, power control is being performed. Therefore, the coasting permission condition C3 is met when the predicted deceleration Gd_p is less than or equal to a predetermined deceleration threshold Gd_th.

[0076] If coasting permission condition C3 is not met, the vehicle driving support device 10 determines "No" in step S320, proceeds directly to step S395, and terminates the processing of this routine. In this case, power control is continued.

[0077] Thus, the vehicle driving support system 10 does not perform coasting control if the deceleration of the vehicle 100 due to coasting control (i.e., predicted deceleration Gd_p) is greater than a predetermined deceleration threshold Gd_th. In other words, the vehicle driving support system 10 prohibits switching from power control to coasting control if the predicted deceleration (i.e., predicted deceleration Gd_p) is greater than a predetermined deceleration threshold Gd_th.

[0078] On the other hand, if coasting permission condition C3 is met, the vehicle driving support system 10 determines "Yes" in step S320, proceeds to step S325, and stops power control. Next, the vehicle driving support system 10 proceeds to step S330 and starts coasting control. Then, the vehicle driving support system 10 proceeds to step S395 and temporarily terminates the processing of this routine.

[0079] Thus, the vehicle driving support system 10 allows switching from power control to coasting control when the predicted deceleration (i.e., predicted deceleration Gd_p) is less than or equal to a predetermined deceleration threshold Gd_th.

[0080] Furthermore, if the vehicle driving support device 10 is performing coasting control when it proceeds to step S310, the vehicle driving support device 10 determines "No" in step S310, proceeds to step S335, and determines whether or not the coasting permission condition C3 is met.

[0081] When the vehicle driving support device 10 proceeds to step S335, coasting control is being performed. Therefore, the coasting permission condition C3 is met when the detected deceleration Gd_d is less than or equal to the predetermined deceleration threshold Gd_th.

[0082] If coasting permission condition C3 is met, the vehicle driving support device 10 determines "Yes" in step S335 and proceeds to step S340 to determine whether or not power start condition C4 has been met.

[0083] The power initiation condition C4 is met when, if there is no preceding vehicle 200, the vehicle speed V1 decreases and reaches the target lower limit speed Vtgt_min. On the other hand, if there is a preceding vehicle 200, the power initiation condition C4 is met when the distance between vehicles D increases and reaches the target upper limit distance between vehicles Dtgt_max.

[0084] If the power start condition C4 is not met, the vehicle driving support system 10 determines "No" in step S340 and proceeds directly to step S395, temporarily ending the processing of this routine. In this case, coasting control continues. On the other hand, if the power start condition C4 is met, the vehicle driving support system 10 determines "Yes" in step S340 and proceeds to step S345, stopping coasting control. Next, the vehicle driving support system 10 proceeds to step S350, starting power control. Then, the vehicle driving support system 10 proceeds to step S395, temporarily ending the processing of this routine.

[0085] Furthermore, if the coasting permission condition C3 is not met when the vehicle driving support device 10 proceeds to step S335, the vehicle driving support device 10 determines "No" in step S335, proceeds to step S355, and stops coasting control. Next, the vehicle driving support device 10 proceeds to step S360 and starts power control.

[0086] Thus, the vehicle driving support device 10 does not perform coasting control if the deceleration of the vehicle 100 due to the execution of coasting control (i.e., detected deceleration Gd_d) is greater than a predetermined deceleration threshold Gd_th. In other words, the vehicle driving support device 10 stops coasting control if the deceleration of the vehicle 100 becomes greater than the predetermined deceleration threshold Gd_th while coasting control is being performed.

[0087] Next, the vehicle driving support system 10 proceeds to step S395 and terminates the processing of this routine.

[0088] Furthermore, if the vehicle driving support device 10 is performing autonomous vehicle speed control when starting power control in step S360, it may be configured to perform power control so as to maintain the vehicle speed V1 at that time. Also, if the vehicle driving support device 10 is performing autonomous inter-vehicle distance control when starting power control in step S360, it may be configured to perform power control so as to maintain the inter-vehicle distance D at that time.

[0089] Furthermore, if the execution request condition C1 is not met when the vehicle driving support system 10 proceeds to step S305, the vehicle driving support system 10 determines "No" in step S305 and proceeds to step S365. If the vehicle driving support system 10 is performing autonomous driving control when it proceeds to step S365, the vehicle driving support system 10 stops the autonomous driving control. Next, the vehicle driving support system 10 proceeds to step S395 and terminates the processing of this routine.

[0090] Furthermore, when a predetermined timing occurs, the vehicle driving support system 10 starts processing from step S400 of the routine shown in Figure 4. Then, the vehicle driving support system 10 proceeds to step S405 and determines whether or not highway condition C5 is met.

[0091] Highway condition C5 is met when the vehicle 100 is traveling on a highway or an expressway. On the other hand, highway condition C5 is not met when the vehicle 100 is not traveling on either a highway or an expressway. For example, highway condition C5 is not met when the vehicle 100 is traveling on an ordinary road. The vehicle driving support system 10 determines whether the vehicle 100 is traveling on a highway or an expressway based on road information IR.

[0092] If highway condition C5 is met, the vehicle driving support system 10 determines "Yes" in step S405 and proceeds to step S410. On the other hand, if highway condition C5 is not met, the vehicle driving support system 10 determines "No" in step S405 and proceeds to step S420.

[0093] When the vehicle driving support system 10 proceeds to step S410, it sets the highway vehicle speed control width WVh as the target vehicle speed control width WVtgt, and also sets the highway inter-vehicle distance control width WDh as the target inter-vehicle distance control width WDtgt. Next, the vehicle driving support system 10 proceeds to step S415, setting the highway deceleration threshold Gd_h as the predetermined deceleration threshold Gd_th. Next, the vehicle driving support system 10 proceeds to step S495, and terminates the processing of this routine.

[0094] In this example, the set vehicle speed control width WVset is set as the highway vehicle speed control width WVh. Also, the set inter-vehicle distance control width WDset is set as the highway inter-vehicle distance control width WDh.

[0095] Meanwhile, when the vehicle driving support device 10 proceeds to step S420, it sets the general road vehicle speed control width WVs as the target vehicle speed control width WVtgt, and also sets the general road inter-vehicle distance control width WDs as the target inter-vehicle distance control width WDtgt.

[0096] In this example, the general road speed control width WVs is set to a smaller value than the highway speed control width WVh. Therefore, when the vehicle 100 is traveling on a general road, the vehicle driving support system 10 sets the general road speed control width WVs, which is smaller than the set speed control width WVset set by the driver, as the target speed control width WVtgt.

[0097] Furthermore, the inter-vehicle distance control width WDs for general roads is set to a smaller value than the inter-vehicle distance control width WDh for expressways. Therefore, when the vehicle 100 is traveling on a general road, the vehicle driving support system 10 sets the target inter-vehicle distance control width WDtgt to be a general road inter-vehicle distance control width WDs that is smaller than the set inter-vehicle distance control width WDset set by the driver.

[0098] Therefore, when the vehicle 100 is traveling on an ordinary road, it will be driven by autonomous driving control within a narrower target vehicle speed range RVtgt or a narrower target inter-vehicle distance range RDtgt compared to when the vehicle 100 is traveling on an expressway or motorway.

[0099] Thus, when the vehicle driving assistance system 10 is traveling on a public road, it sets the target vehicle speed control width WVtgt and the target inter-vehicle distance control width WDtgt to smaller values ​​compared to when the vehicle driving assistance system 100 is traveling on a highway or an expressway. Therefore, when the vehicle driving assistance system 10 is traveling on a public road, it narrows the target vehicle speed range RVtgt and the target inter-vehicle distance range RDtgt compared to when the vehicle driving assistance system 100 is traveling on a highway or an expressway.

[0100] Furthermore, the general road vehicle speed control width WVs is set to a smaller value than the highway vehicle speed control width WVh, but the general road vehicle speed control width WVs is set to a value greater than zero. Similarly, the general road inter-vehicle distance control width WDs is set to a smaller value than the highway inter-vehicle distance control width WDh, but the general road inter-vehicle distance control width WDs is set to a value greater than zero.

[0101] Next, the vehicle driving support device 10 proceeds to step S425, setting the general road deceleration threshold Gd_s as the predetermined deceleration threshold Gd_th.

[0102] In this example, the highway deceleration threshold Gd_h is set to a larger value than the general road deceleration threshold Gd_s. Therefore, when vehicle 100 is traveling on a general road, it is driven by autonomous driving control within a smaller deceleration range compared to when vehicle 100 is traveling on a highway or expressway.

[0103] Thus, the vehicle driving assistance system 10 sets the predetermined deceleration threshold Gd_th to a smaller value when the road on which the vehicle 100 is traveling is a public road compared to when the road on which the vehicle 100 is traveling is a highway or an expressway.

[0104] Furthermore, while the deceleration threshold Gd_s for general roads is set to a smaller value than the deceleration threshold Gd_h for expressways, the deceleration threshold Gd_s for general roads is set to a value greater than zero.

[0105] Next, the vehicle driving support system 10 proceeds to step S495 and terminates the processing of this routine.

[0106] The above describes the operation of the vehicle driving assistance device 10.

[0107] According to the vehicle driving support system 10, when the vehicle 100 is traveling on an ordinary road, the target vehicle speed range RVtgt and the target inter-vehicle distance range RDtgt are made relatively narrow. Therefore, when the vehicle 100 is coasted by autonomous driving control, it is suppressed that the vehicle speed V1 becomes excessively low or that the increase or decrease in the vehicle speed V1 becomes excessively large. As a result, the vehicle 100 can coast appropriately when traveling on an ordinary road.

[0108] Furthermore, the present invention is not limited to the embodiments described above, and various modifications can be adopted within the scope of the present invention. [Explanation of symbols]

[0109] 10...Vehicle driving assistance system, 70...Surrounding information acquisition device, 81...GPS signal receiver, 82...Map database, 90...ECU, 100...Own vehicle, 200...Preceding vehicle

Claims

1. The system includes a control device that performs autonomous driving control, which involves alternately switching between power control to propel the vehicle and coasting control to allow the vehicle to coast, thereby enabling the vehicle to move autonomously. The control device switches between the power control and the coasting control so that the vehicle's speed or the distance between the vehicle and the preceding vehicle falls within a predetermined range of speed or distance. In a vehicle driving assistance system, The control device narrows the predetermined range when the road on which the vehicle is traveling is a public road compared to when the road on which the vehicle is traveling is a highway or an expressway. Vehicle driving assistance system.

2. In the vehicle driving support device according to claim 1, The control device shall not perform the coasting control if the deceleration of the vehicle due to the execution of the coasting control is greater than a predetermined deceleration threshold. Vehicle driving assistance system.

3. In the vehicle driving support device according to claim 2, The control device sets the predetermined deceleration threshold to a smaller value when the road on which the vehicle is traveling is a public road compared to when the road on which the vehicle is traveling is a highway or an expressway. Vehicle driving assistance system.

4. In the vehicle driving support device according to claim 1, The control device is During the execution of the aforementioned power control, the deceleration of the vehicle is predicted when the power control is switched to the aforementioned coasting control. When the road on which the vehicle is traveling is a public road, the predetermined deceleration threshold is set to a smaller value compared to when the road on which the vehicle is traveling is a highway or an expressway. If the predicted deceleration is less than or equal to the predetermined deceleration threshold, the system allows switching from the power control to the coasting control. If the predicted deceleration is greater than the predetermined deceleration threshold, the switching from power control to coasting control is prohibited. Vehicle driving assistance system.

5. In the vehicle driving support device according to claim 1, The control device is When the road on which the vehicle is traveling is a public road, the predetermined deceleration threshold is set to a smaller value compared to when the road on which the vehicle is traveling is a highway or an expressway. If the deceleration of the vehicle becomes greater than the predetermined deceleration threshold during the execution of the coasting control, the coasting control is stopped. Vehicle driving assistance system.

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