Vehicle control device

Abstract

To provide a vehicle control device capable of executing ACC acceleration / deceleration control comfortable for a driver even when an own vehicle traveling on a curved road under ACC can no longer detect a preceding vehicle as a target to follow.SOLUTION: A vehicle control device 10 comprises: a preceding vehicle detection section 43 to detect a preceding vehicle; a curve detection section 45 to detect a curved road section CR from a road R in a direction of travel of the own vehicle; and a travel control section 47 to control travel of the own vehicle based on detection results from the preceding vehicle detection section 43 and the curve detection section 45. The travel control section 47 switches acceleration and deceleration of the own vehicle when the own vehicle, under follow-up travel control, loses detection of the preceding vehicle while traveling on the curved road section CR based on a first position, which is a position of the own vehicle when the preceding vehicle is no longer detected and a second position, which is a position of the preceding vehicle when the preceding vehicle is no longer detected by the own vehicle.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] An embodiment of the present invention relates to a vehicle control device. [Background technology]

[0002] There are known vehicle cruise control devices equipped with an adaptive cruise control (ACC) device. The ACC device drives the vehicle at a constant speed when there is no preceding vehicle, and when there is a preceding vehicle, it drives the vehicle to follow the preceding vehicle while maintaining a constant distance from the preceding vehicle. Hereinafter, such vehicle cruise control using an ACC device may be simply referred to as ACC. When a vehicle following a preceding vehicle loses sight of the preceding vehicle and accelerates to transition to constant speed traveling, the vehicle cruise control device suppresses the acceleration required to transition to constant speed traveling, and maintains the current vehicle speed or automatically decelerates the vehicle, only when the vehicle is located before a small radius corner. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2002-12053 Summary of the Invention [Problem to be solved by the invention]

[0004] Generally, when a driver manually drives a vehicle without using ACC, the driver decelerates the vehicle before a curved road, and stops decelerating the vehicle in a steady circular section with a constant curvature, which is a section midway along the curved road, and drives the vehicle at a constant speed.

[0005] However, when a vehicle running ACC is running on a curve and the vehicle loses sight of the preceding vehicle to be followed, the vehicle cruise control device simply maintains the vehicle speed or decelerates the vehicle. Therefore, the acceleration and deceleration of the vehicle differs from when the driver manually drives the vehicle on a curve, and the vehicle cruise control device causes the driver to feel uncomfortable.

[0006] Therefore, the present invention provides a vehicle control device that can perform acceleration and deceleration control of ACC in a way that is comfortable for the driver, even when a vehicle running ACC is unable to detect a preceding vehicle as a vehicle to be followed when traveling on a curved road. [Means for solving the problem]

[0007] In order to solve the above-mentioned problems, a vehicle control device according to an embodiment of the present invention includes a preceding vehicle detection unit that detects a preceding vehicle, a curve detection unit that detects a curved road from a road in the traveling direction of the host vehicle, and a travel control unit that performs travel control of the host vehicle based on the detection results of the preceding vehicle detection unit and the curve detection unit, and when the preceding vehicle is detected, the travel control unit performs follow-up travel control to make the host vehicle follow the preceding vehicle within a set inter-vehicle time, and when the preceding vehicle is not detected, performs constant speed travel control to make the host vehicle travel at a constant speed at a set vehicle speed, and If the curved road is detected while the following cruise control or the constant speed cruise control is being performed, pre-curve deceleration control is performed to decelerate the host vehicle just before the entrance to the curved road, and if the preceding vehicle is no longer detected when the host vehicle is traveling on the curved road while the following cruise control is being performed, acceleration / deceleration of the host vehicle is switched based on a first position, which is the position of the host vehicle obtained from the detection result of the curve detection unit and is the position of the host vehicle when the preceding vehicle is no longer detected, and a second position, which is the position of the preceding vehicle when the preceding vehicle is no longer detected. [Effects of the Invention]

[0008] The present invention provides a vehicle control device that can perform acceleration / deceleration control of ACC in a way that is comfortable for the driver, even when a vehicle running ACC cannot detect a preceding vehicle as a vehicle to be followed when traveling on a curved road. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a schematic diagram of a vehicle control system including a vehicle control device according to an embodiment of the present invention. [Figure 2] 1 is a schematic diagram showing the position of a vehicle and the position of a preceding vehicle to be followed when traveling around a curved road with two lanes, one lane on each side, in a vehicle control device according to an embodiment of the present invention; [Figure 3] (A) A schematic diagram showing the predetermined path length from the vehicle to the second clothoid section in a steady circle section of a curved road with a small curvature in a vehicle control device according to an embodiment of the present invention; (B) A schematic diagram showing the predetermined path length from the vehicle to the second clothoid section in a steady circle section of a curved road with a large curvature in a vehicle control device according to an embodiment of the present invention. [Figure 4] 4 is a flowchart showing the contents of acceleration / deceleration control of the host vehicle when the host vehicle, in which ACC is being executed, travels on a curved road in the vehicle control device according to the embodiment of the present invention. [Figure 5] 5 is a flowchart showing the processes following connectors A and B in the flowchart of FIG. 4. [Figure 6] 5 is a flowchart showing an alternative process to the process surrounded by the two-dot chain line P in FIG. 4. DETAILED DESCRIPTION OF THE INVENTION

[0010] An embodiment of a vehicle control device according to the present invention will be described with reference to FIGS.

[0011] FIG. 1 is a schematic diagram of a vehicle control system including a vehicle control device according to an embodiment of the present invention.

[0012] The vehicle control device 10 shown in Fig. 1 is a type of automated driving system that provides driving assistance to a driver by timely performing adaptive cruise control (ACC) on a vehicle equipped with a vehicle control system 100 including the vehicle control device 10. Driving assistance refers to the automated driving system automatically and continuously performing at least one of the following operations: acceleration / deceleration of the vehicle, including starting and stopping the vehicle, and steering the vehicle, in a limited and continuous manner.

[0013] Furthermore, the vehicle control system 100 is applicable not only to engine vehicles but also to electric vehicles, hybrid vehicles, fuel cell vehicles, etc. Furthermore, a lane keeping assist (LKA) that provides driving assistance by automatically controlling steering, in other words, the lateral position (left-right position) of the vehicle, may be used in combination with the ACC for a vehicle equipped with the vehicle control system 100. Hereinafter, a vehicle equipped with the vehicle control system 100 will be referred to as the "host vehicle."

[0014] When a preceding vehicle, which is a vehicle ahead of the host vehicle in the same lane as the host vehicle, is detected, the ACC causes the host vehicle to follow the preceding vehicle within a preset inter-vehicle time. In other words, the ACC brings the host vehicle within a predetermined distance from the preceding vehicle and automatically accelerates or decelerates the host vehicle within a preset vehicle speed to maintain this predetermined distance, causing the host vehicle to follow the preceding vehicle. Such following driving by the ACC may be referred to as a "following driving mode" below. Furthermore, when a preceding vehicle is not detected, the ACC causes the host vehicle to travel at a constant speed set in advance. Such constant speed driving by the ACC may be referred to as a "constant speed driving mode" below. The ACC allows the driver to drive the host vehicle without depressing the accelerator pedal or brake pedal except when necessary.

[0015] Hereinafter, the vehicle control device 10 and the vehicle control system 100 including the vehicle control device 10 will be described in detail with reference to FIG.

[0016] The vehicle control system 100 includes an in-vehicle sensor 1, an in-vehicle navigation device 3, an accelerator control device 5, a brake control device 7, an ACC switch 8, an ACC setting switch 9, and a vehicle control device 10. The in-vehicle sensor 1, the in-vehicle navigation device 3, the accelerator control device 5, the brake control device 7, the ACC switch 8, the ACC setting switch 9, and the vehicle control device 10 are connected to each other so as to be able to communicate with each other via an in-vehicle network 11. The in-vehicle network 11 is, for example, a bus-type network that uses CAN (Controller Area Network) as a communication protocol.

[0017] The on-vehicle sensor 1 is provided on the vehicle, acquires information about objects around the vehicle and information about the state of the vehicle, and outputs the information to the vehicle control device 10. The on-vehicle sensor 1 includes a camera sensor 21, a radar sensor 22, a wheel speed sensor 23, an acceleration sensor 24, and a yaw rate sensor 25.

[0018] The camera sensor 21 captures images of the area ahead of the vehicle, and generates image information by acquiring images of objects in front of the vehicle and their surroundings. The camera sensor 21 includes an image processing unit (not shown) that acquires object information from the generated image information, including, for example, the distance from the vehicle to the object and the orientation of the object relative to the vehicle. The camera sensor 21 is attached to the windshield, the back of the rearview mirror, the front of the vehicle, or the like, in order to capture images of the area ahead.

[0019] Based on the results of transmitting and receiving the probe waves, the radar sensor 22 acquires object information, including, for example, the distance from the vehicle to the object that reflected the probe waves and the object's orientation relative to the vehicle. Specifically, the radar sensor 22 in this embodiment is a millimeter-wave radar sensor that scans and outputs millimeter-wave radio waves as probe waves within a predetermined angular range in front of the vehicle and detects the reflected waves. The radar sensor 22 can then determine the object's position relative to the vehicle by using the time it takes for the millimeter waves to travel back and forth between the object that reflected the millimeter waves and the object's distance from the vehicle, as well as angle data indicating the object's orientation relative to the vehicle. Note that the radar sensor 22 is not limited to a millimeter-wave radar sensor; it may also be a laser radar sensor that uses laser light as the probe wave or a sonar radar sensor that uses ultrasonic waves as the probe wave. Furthermore, the radar sensor 22 may use two or more of these types of radar sensors.

[0020] The wheel speed sensor 23 is provided on each wheel of the vehicle and detects the rotation speed of the wheel. Based on the wheel speed detected by the wheel speed sensor 23, the running speed of the vehicle, i.e., the vehicle speed, can be detected.

[0021] The acceleration sensor 24 detects the acceleration of the vehicle body in the longitudinal and lateral directions of the vehicle, that is, the acceleration sensor 24 can detect the acceleration and deceleration of the vehicle.

[0022] The yaw rate sensor 25 detects the rotational angular velocity of the vehicle about a vertical axis, that is, the yaw rate.

[0023] The in-vehicle navigation device 3 includes a GNSS receiver 31, which is a receiver for a Global Navigation Satellite System (GNSS) capable of acquiring highly accurate position information using multiple satellites including a Global Positioning System (GPS), and highly accurate map information 33 containing latitude and longitude information tailored to the positioning accuracy of the GNSS receiver 31. The GNSS receiver 31 identifies the current position of the vehicle on the Earth's surface. The map information 33 includes, for example, information on the position of roads on the Earth's surface and information describing the shape of the road, including curves. The information describing the shape of the curve includes the curvature and / or radius of curvature of the curve for each lane, the length of the curve, and whether or not the road is an S-curve. The in-vehicle navigation device 3 outputs the current position information of the vehicle obtained from the GNSS receiver 31 to the vehicle control device 10.

[0024] The accelerator control device 5 controls the engine and / or the electric motor that generates the propulsive force of the vehicle, based on an acceleration request signal that is output from the vehicle control device 10 and that indicates a request for acceleration.

[0025] The brake control device 7 controls the brakes that generate braking force for the vehicle based on a deceleration request signal that indicates a request for deceleration output from the vehicle control device 10. The brake control device 7 also includes a brake pedal (not shown) and a brake position sensor (not shown) that is provided on the brake pedal and detects the amount of depression of the brake pedal. The brake position sensor outputs the amount of depression of the brake pedal by the driver of the vehicle to the vehicle control device 10 as sensor information.

[0026] The ACC switch 8 is located near the driver's seat and is operated by the driver. The ACC switch 8 is operated when the driver requests the start or end of ACC. When the ACC switch 8 is turned on by the driver while ACC is not operating, the ACC switch 8 outputs an ACC start request signal indicating that the driver is requesting the start of ACC to the vehicle control device 10. On the other hand, when the ACC switch 8 is turned off by the driver while ACC is operating, the ACC switch 8 outputs an ACC end request signal indicating that the driver is requesting the end of ACC to the vehicle control device 10.

[0027] The ACC setting switch 9 is a switch that is provided near the ACC switch 8 and is operated by the driver. The ACC setting switch 9 is a switch that the driver operates to set a set inter-vehicle time and a set vehicle speed. The set inter-vehicle time is the time that the host vehicle sets between itself and the preceding vehicle in ACC follow-up mode. The set vehicle speed is the vehicle speed that the host vehicle maintains in ACC constant speed mode. Alternatively, instead of setting a set inter-vehicle time, a set inter-vehicle distance that is calculated by multiplying the set inter-vehicle time by the vehicle speed may be set. When the ACC setting switch 9 is operated to set the set inter-vehicle time and the set vehicle speed, the ACC setting switch 9 outputs a setting signal that indicates the set inter-vehicle time and the set vehicle speed to the vehicle control device 10.

[0028] The vehicle control device 10 is configured as a computer equipped with a central processing unit (CPU), an input / output interface, and storage devices such as ROM and RAM. Upon receiving inputs of information from the on-board sensors 1 and the on-board navigation device 3, an ACC start request signal and an ACC end request signal from the ACC switch 8, and a setting signal from the ACC setting switch 9, the vehicle control device 10 executes predetermined calculations related to vehicle driving control, and outputs control signals according to the results to the accelerator control device 5 and the brake control device 7. The control signals are an acceleration request signal to the accelerator control device 5 and a deceleration request signal to the brake control device 7.

[0029] The vehicle control device 10 includes, for example, an ACC determination unit 41 that determines whether the ACC switch 8 is on or not, a preceding vehicle detection unit 43 that detects a preceding vehicle, a curve detection unit 45 that detects a curved road from the road in the direction of travel of the vehicle, a yaw rate determination unit 46 that determines whether the yaw rate output from the yaw rate sensor 25 exceeds an upper limit value corresponding to the vehicle speed of the vehicle, and a driving control unit 47 that controls the driving of the vehicle, i.e., controls the acceleration and deceleration of the ACC for the vehicle, based on the detection results of the preceding vehicle detection unit 43 and the curve detection unit 45 and the determination result of the yaw rate determination unit 46.

[0030] When the ACC switch 8 is turned on and an ACC start request signal is input from the ACC switch 8, the ACC determination unit 41 generates an ACC operation signal and outputs it to the preceding vehicle detection unit 43, the curve detection unit 45, and the driving control unit 47. On the other hand, when the ACC switch 8 is turned off by the driver and an ACC end request signal is input from the ACC switch 8, the ACC determination unit 41 generates an ACC stop signal and outputs it to the preceding vehicle detection unit 43, the curve detection unit 45, and the driving control unit 47.

[0031] When the preceding vehicle detection unit 43 receives an ACC operation signal from the ACC determination unit 41, it performs a preceding vehicle detection process for identifying and detecting a preceding vehicle based on at least one of the object information output from the camera sensor 21 and the object information output from the radar sensor 22. When a preceding vehicle is detected by the preceding vehicle detection process, the preceding vehicle detection unit 43 outputs preceding vehicle information including the distance and direction from the host vehicle to the preceding vehicle, as well as the vehicle speed and deceleration of the preceding vehicle, to the cruise control unit 47, and when a preceding vehicle is not detected by the preceding vehicle detection process, it outputs a preceding vehicle non-detection signal to the cruise control unit 47 indicating that a preceding vehicle has not been detected.

[0032] 2 is a schematic diagram showing the position of the host vehicle and the position of a preceding vehicle to be followed when traveling around a curved road with two lanes, one lane on each side, in a vehicle control device according to an embodiment of the present invention. Note that the preceding vehicle to be followed may be referred to as a "target vehicle" or simply as a "target" hereinafter.

[0033] As shown in FIG. 2, upon receiving an ACC activation signal from the ACC determination unit 41, the curve detection unit 45 performs a detection process to identify and detect a curved road CR from the road R in the vehicle's traveling direction, for example, by referring to the map information 33 based on the vehicle's current position information output from the in-vehicle navigation device 3. The curve detection unit 45 may also detect a curved road CR based on object information output from the camera sensor 21 or the radar sensor 22. When the curve detection unit 45 detects a curved road CR, it further obtains information such as the curvature, radius of curvature, and length of the detected curved road CR. The curve detection unit 45 outputs a curve detection signal indicating that the curved road CR has been detected and the above information regarding the curved road CR to the driving control unit 47. Note that when a curved road CR is detected, the vehicle is usually traveling near the curved road CR.

[0034] 2, the curved road CR detected by the curve detection unit 45 usually has a first clothoid section Sc1 that includes the entrance of the curved road CR and is a section where the curvature of the curved road CR gradually increases until it reaches a constant value, a steady circular section Src that is a section that continues from the first clothoid section Sc1 and where the curvature remains constant, and a second clothoid section Sc2 that includes the exit of the curved road CR and is a section that continues from the steady circular section Src and where the curvature gradually decreases from the constant value. The entrance and exit of the curved road CR are each continuous with a straight road SR.

[0035] The curve detection unit 45 determines whether the vehicle is located immediately before the entrance to the curved road CR, the first clothoid section Sc1, the steady circle section Src, the second clothoid section Sc2, or the exit of the curved road CR (the end of the second clothoid section Sc2), and outputs a curve section determination signal corresponding to each determination result to the cruise control unit 47. The curve detection unit 45 can also calculate and obtain the path length of the vehicle (the vehicle's travel path length) from the vehicle's position to the start position of each section of the curved road CR along which the vehicle will travel. The curve detection unit 45 outputs the calculated path length of the vehicle to the cruise control unit 47.

[0036] The preceding vehicle detection unit 43 determines whether the position of the preceding vehicle is at least in the first clothoid section Sc1 of the curved road CR, the steady circle section Src, the second clothoid section Sc2, the exit of the curved road CR (the end of the second clothoid section Sc2), or after the exit of the curved road CR (the section immediately before the exit of the curved road), and outputs a preceding vehicle curve section determination signal according to each determination result to the driving control unit 47.

[0037] The yaw rate determination unit 46 acquires the yaw rate generated by the host vehicle while traveling on the curved road CR from the yaw rate sensor 25, and determines whether the acquired yaw rate exceeds an upper limit value corresponding to the vehicle speed of the host vehicle. The yaw rate determination unit 46 outputs a yaw rate determination signal indicating the yaw rate determination result to the traveling control unit 47.

[0038] When a preceding vehicle is detected based on the ACC operation signal from the ACC determination unit 41 and the preceding vehicle information from the preceding vehicle detection unit 43, the cruise control unit 47 performs follow-up cruise control, which causes the host vehicle to follow the preceding vehicle within a set inter-vehicle time previously set in the ACC setting switch 9. This follow-up cruise control by the cruise control unit 47 is a follow-up cruise mode of the ACC. Furthermore, when a preceding vehicle is not detected based on the ACC operation signal from the ACC determination unit 41 and the preceding vehicle non-detection signal from the preceding vehicle detection unit 43, the cruise control unit 47 performs constant-speed cruise control, which causes the host vehicle to travel at a constant speed at a set vehicle speed previously set in the ACC setting switch 9. This constant-speed cruise control by the cruise control unit 47 is a constant-speed cruise mode of the ACC. In order to perform follow-up cruise control, the cruise control unit 47 outputs an acceleration request signal to the accelerator control unit 5 or a deceleration request signal to the brake control unit 7 at appropriate times to control the acceleration or deceleration of the host vehicle. In addition, in order to perform constant speed traveling control, the traveling control unit 47 outputs an acceleration request signal to the accelerator control device 5 or outputs a deceleration request signal to the brake control device 7 at an appropriate time to control the acceleration or deceleration of the vehicle.

[0039] Furthermore, when the cruise control unit 47 receives a curve detection signal from the curve detection unit 45 and a determination signal indicating that the vehicle is immediately before the entrance to the curved road CR while performing the following cruise control or the constant speed cruise control, the cruise control unit 47 performs pre-curve deceleration control, which starts decelerating the vehicle immediately before the entrance to the curved road CR, in priority over the following cruise control or the constant speed cruise control. At this time, the following cruise control or the constant speed cruise control is temporarily stopped. This pre-curve deceleration control corresponds to one of the functions called the "speed management function" in the ACC. The cruise control unit 47 outputs a deceleration request signal to the brake control device 7 to perform pre-curve deceleration control.

[0040] In addition, while performing follow-up driving control or constant speed driving control, if the curvature of the curved road CR detected by the curve detection unit 45 is smaller than a predetermined value and the curved road CR is a gentle curve, the driving control unit 47 may determine that deceleration of the vehicle is not necessary and may not perform pre-curve deceleration control.

[0041] Furthermore, based on the determination result from the yaw rate determination unit 46, the cruise control unit 47 performs curve deceleration control, which decelerates the host vehicle while traveling on a curved road CR so that the yaw rate generated by the host vehicle does not exceed an upper limit value corresponding to the vehicle speed, in priority over the follow-up cruise control or constant-speed cruise control. At this time, the follow-up cruise control or constant-speed cruise control is temporarily stopped. This curve deceleration control also corresponds to one of the speed management functions described above. The cruise control unit 47 outputs a deceleration request signal to the brake control device 7 at an appropriate time to perform curve deceleration control. Note that curve deceleration control is usually performed after pre-curve deceleration control.

[0042] As described above, when a driver manually drives a vehicle without using ACC, the driver typically decelerates the vehicle immediately before the entrance to a curved road and stops decelerating the vehicle in a steady circle section, which is a section of the curved road with a constant curvature, to drive the vehicle at a constant speed. In other words, the vehicle acceleration / deceleration is switched depending on the section of the curved road. Meanwhile, as shown in FIG. 2 , for example, when a host vehicle with ACC running is traveling on a curved road CR, the host vehicle may not be detected in the first clothoid section Sc1, the steady circle section Src, or the second clothoid section Sc2 immediately before the entrance to the curved road CR. In this case, if the vehicle control device 10 simply maintains or decelerates the host vehicle's speed, the acceleration / deceleration of the host vehicle will be significantly different from the acceleration / deceleration that occurs when the driver manually drives the vehicle on the curved road CR, causing the driver to feel uncomfortable.

[0043] Therefore, when the host vehicle is traveling on a curved road CR while the following cruise control is being executed, if a preceding vehicle that had been detected up until that point is no longer detected, the cruise control unit 47 switches the acceleration / deceleration of the host vehicle based on a first position, which is the host vehicle's position when the preceding vehicle is no longer detected and is obtained from the detection results of the curve detection unit 45, and a second position, which is the host vehicle's position when the preceding vehicle is no longer detected. In other words, the cruise control unit 47 performs ACC acceleration / deceleration control of the host vehicle based on the first position and the second position, prioritizing it over following cruise control. This allows the cruise control unit 47 to perform acceleration / deceleration of the host vehicle in the same manner as the vehicle accelerates / decelerates in accordance with each section of the curved road CR when the driver manually drives the vehicle on the curved road CR, if the host vehicle is traveling on a curved road CR while the following cruise control unit 47 is executing ACC and the preceding vehicle that is the vehicle to be followed is no longer detected. In other words, even if the host vehicle is traveling on a curved road CR while the host vehicle is traveling on the curved road CR while the following cruise control unit 47 is no longer able to detect the preceding vehicle that is the vehicle to be followed, the cruise control unit 47 can perform ACC acceleration / deceleration control that is comfortable for the driver. Hereinafter, the second position may be referred to as the "lost position of the preceding vehicle" or simply as the "lost position."

[0044] The following provides a detailed description of the host vehicle acceleration / deceleration switching (host vehicle acceleration / deceleration control or host vehicle cruise control) performed by the cruise control unit 47 for the host vehicle while ACC is being executed. The host vehicle acceleration / deceleration switching described below is always performed with priority over follow-up cruise control or constant speed cruise control, and follow-up cruise control or constant speed cruise control is temporarily suspended. The host vehicle acceleration / deceleration switching described below can be considered as an ACC driving mode or speed management function. The cruise control unit 47 switches the host vehicle acceleration / deceleration, i.e., performs ACC acceleration / deceleration control of the host vehicle, while outputting an acceleration request signal to the accelerator control device 5 or a deceleration request signal to the brake control device 7 as appropriate.

[0045] When the first position is immediately before the entrance to the curved road CR and the second position is within the first clothoid section Sc1, the driving control unit 47 may decelerate the vehicle at the deceleration rate of the preceding vehicle immediately before the second position until the vehicle reaches the steady circle section Src.

[0046] Specifically, as shown in FIG. 2, when the preceding vehicle is no longer detected in the first clothoid section Sc1, it is highly likely that the preceding vehicle continues traveling on the curved road CR. In this case, if the host vehicle travels in a manner that approaches the preceding vehicle, the driver of the host vehicle may feel fear. Therefore, when the preceding vehicle is no longer detected in the first clothoid section Sc1, the cruise control unit 47 decelerates the host vehicle at the same deceleration rate as when the preceding vehicle was decelerating, so that the host vehicle does not approach the preceding vehicle. In this way, the cruise control unit 47 improves the comfort felt by the driver when the host vehicle with ACC running travels on the curved road CR, without making the driver feel fear associated with the host vehicle approaching the preceding vehicle.

[0047] The travel control unit 47 decelerates the host vehicle at the deceleration of the preceding vehicle immediately before the second position until the host vehicle reaches the steady circle section Src. However, this deceleration is only performed up to a predetermined vehicle speed or a predetermined deceleration so that the host vehicle does not stop or become too slow. The predetermined deceleration is, for example, 0.35 G (3.43 m / s 2)

[0048] Furthermore, when the first position is immediately before the entrance to the curved road CR and the second position is within the first clothoid section Sc1, the cruise control unit 47 may decelerate the host vehicle at a larger deceleration between the deceleration of the preceding vehicle immediately before the second position and the deceleration in the pre-curve deceleration control until the host vehicle reaches the steady circle section Src. By doing so, for example, when there is a preceding vehicle traveling on the curved road CR at a high vehicle speed without excessive deceleration, the host vehicle will enter the curved road CR at a slower vehicle speed than the preceding vehicle. Therefore, the cruise control unit 47 enables the host vehicle to travel on the curved road CR while giving the driver a sense of security.

[0049] 2, the cruise control unit 47 may also cause the host vehicle to travel at a constant speed when the host vehicle is located within a steady circular section Src. By doing so, the host vehicle travels at a constant speed in the steady circular section Src, where the curvature is constant and there is no need to decelerate the host vehicle, and suppresses acceleration control of the host vehicle when a detected preceding vehicle is no longer detected and the ACC constant speed cruise mode (constant speed cruise control) is enabled. Therefore, the cruise control unit 47 further improves the comfort felt by the driver when the host vehicle travels on a curved road CR with ACC running.

[0050] When the first position is immediately before the entrance to the curved road CR and the second position is within the first clothoid section Sc1, the host vehicle is decelerated at the deceleration of the preceding vehicle immediately before the second position until the host vehicle reaches the steady circle section Src, and the host vehicle is allowed to travel at a constant speed within the steady circle section Src. This series of cruise control is referred to as "first clothoid section target lost control." The end point of the first clothoid section target lost control is the exit of the curved road CR. After the exit of the curved road CR, that is, after the first clothoid section target lost control ends, the cruise control unit 47 resumes the following cruise control or constant speed cruise control and starts accelerating the host vehicle. Furthermore, when the first position is immediately before the entrance to the curved road CR and the second position is within the first clothoid section Sc1, the host vehicle is decelerated at the larger of the deceleration of the preceding vehicle immediately before the second position and the deceleration in the pre-curve deceleration control until the host vehicle reaches the steady circle section Src, and the host vehicle is allowed to travel at a constant speed within the steady circle section Src, which is a variation of the first clothoid section target lost control. Furthermore, if the preceding vehicle that had once become undetectable becomes detected again during the first clothoid section target lost control, the cruise control unit 47 stops the first clothoid section target lost control and performs follow-up cruise control.

[0051] In addition, when the first position is immediately before the entrance to the curved road CR and the second position is in the steady circle section Src, the driving control unit 47 performs pre-curve deceleration control until the vehicle reaches the steady circle section Src, and when the position of the vehicle while traveling is within the steady circle section Src, the driving control unit 47 may cause the vehicle to travel at a constant speed.

[0052] Specifically, as shown in Fig. 2, when the preceding vehicle is no longer detected in the steady circle section Src, there is a high possibility that the preceding vehicle will accelerate and travel at a constant speed without decelerating. In this case, the cruise control unit 47 performs pre-curve deceleration control to prevent the host vehicle from approaching the preceding vehicle, thereby allowing the host vehicle to enter the curve while giving the driver a sense of security. Furthermore, the cruise control unit 47 causes the host vehicle to travel at a constant speed within the steady circle section Src to prevent the host vehicle from approaching the preceding vehicle and from unnecessarily decelerating the host vehicle, thereby further improving the comfort felt by the driver.

[0053] When the first position is immediately before the entrance to the curved road CR and the second position is within the steady circle section Src, a series of driving controls in which pre-curve deceleration control is performed until the host vehicle reaches the steady circle section Src, and the host vehicle is driven at a constant speed within the steady circle section Src is referred to as "steady circle section target lost control." The end point of the steady circle section target lost control, the processing performed by the driving control unit 47 after the steady circle section target lost control ends, and the processing performed by the driving control unit 47 when a preceding vehicle is detected again during the steady circle section target lost control are the same as those in the first clothoid section target lost control.

[0054] When the first position is immediately before the entrance to the curved road CR and the second position is within the second clothoid section Sc2, the cruise control unit 47 may perform pre-curve deceleration control until the host vehicle reaches the steady circle section Src. Note that this pre-curve deceleration control is specifically referred to as "curve exit section target lost control."

[0055] Specifically, as shown in Fig. 2, when the preceding vehicle is no longer detected in the second clothoid section Sc2, the preceding vehicle is approaching the exit of the curved road CR and is likely to accelerate thereafter. Therefore, the cruise control unit 47 performs pre-curve deceleration control to prevent the host vehicle from approaching the preceding vehicle, giving the driver a sense of security as the host vehicle enters the curve, and decelerates the host vehicle until the host vehicle reaches the steady circle section Src. After that, even if the host vehicle accelerates, it does not approach the preceding vehicle in a way that would make the driver feel fear of the preceding vehicle, so the cruise control unit 47 further improves the comfort felt by the driver on the curved road CR.

[0056] Fig. 3(A) is a schematic diagram showing a predetermined route length from the host vehicle to a second clothoid section in a steady circle section of a curved road with a small curvature in a vehicle control device according to an embodiment of the present invention, and Fig. 3(B) is a schematic diagram showing a predetermined route length from the host vehicle to the second clothoid section in a steady circle section of a curved road with a large curvature in a vehicle control device according to an embodiment of the present invention. Note that road R shown in Fig. 3(A) and Fig. 3(B) is a two-lane road with one lane on each side, similar to Fig. 2.

[0057] As shown in Figures 3(A) and 3(B), when the first position is immediately before the entrance to the curved road CR and the second position is within the second clothoid section Sc2, the driving control unit 47 may cause the vehicle to travel at a constant speed in the steady circular section Src until the path length from the vehicle to the second clothoid section Sc2 reaches a predetermined path length Lp, which becomes shorter as the radius of curvature of the steady circular section Src becomes smaller.

[0058] Specifically, as described above, when the preceding vehicle is no longer detected in the second clothoid section Sc2, the preceding vehicle is likely to accelerate thereafter. In this case, even if the host vehicle accelerating while traveling through the steady circle section Src is accelerated, the host vehicle is unlikely to approach the preceding vehicle. In particular, when the radius of curvature of the steady circle section Src is relatively large, the driver will likely want to accelerate the host vehicle traveling through the steady circle section Src at an earlier stage. Therefore, while the host vehicle is traveling through the steady circle section Src, the cruise control unit 47 causes the host vehicle to travel at a constant speed up to a position where the driver is likely to accelerate the host vehicle, and then makes the host vehicle ready for acceleration. This enables the driver to switch the acceleration / deceleration of the host vehicle as if the driver were manually driving the vehicle without using the ACC. In other words, when the host vehicle is traveling on a curved road CR with the ACC running, the cruise control unit 47 can timely switch the acceleration / deceleration of the host vehicle even if the preceding vehicle is no longer detected, thereby further improving the comfort felt by the driver.

[0059] In addition, when the vehicle ahead is no longer detected while the vehicle is traveling on a curved road CR having a curvature radius equal to or less than a predetermined value, the traveling control unit 47 may lower the vehicle speed of the vehicle during deceleration control while traveling on a curve compared to when the vehicle ahead was detected.

[0060] Specifically, when the host vehicle is traveling on a sharply curved road CR and the preceding vehicle is no longer detected, the preceding vehicle may subsequently further decelerate. In this case, if the host vehicle is not decelerated at a certain value or more, regardless of the deceleration of the preceding vehicle immediately before the position where the preceding vehicle was lost, the driver will feel fearful of the preceding vehicle approaching the host vehicle. Therefore, when the preceding vehicle is no longer detected while the host vehicle is traveling on a sharply curved road CR with a curvature radius equal to or less than a predetermined value, the cruise control unit 47 decelerates the host vehicle to a vehicle speed that is slower than the vehicle speed that is considered acceptable when the host vehicle is traveling on a normal curved road CR that is not steep, thereby giving the driver a sense of security and further improving the comfort felt by the driver.

[0061] Furthermore, when a preceding vehicle is detected while the cruise control unit 47 is performing the deceleration control for a curve, the cruise control unit 47 may learn the relationship between the curvature of the curved road CR, the set vehicle speed for the constant speed cruise control, and whether or not the driver brakes the host vehicle. Then, when the cruise control unit 47 performs the deceleration control for a curved road CR having a curvature where the frequency of braking was low as a result of this learning, the cruise control unit 47 may increase the upper limit value of the yaw rate corresponding to the vehicle speed of the host vehicle, thereby increasing the vehicle speed of the host vehicle in the deceleration control for a curve. Note that the deceleration control for a curve that decelerates the host vehicle to a vehicle speed based on such learning is referred to as "learning-type deceleration control for a curve."

[0062] Specifically, a driver who sets a high set vehicle speed for the constant-speed cruise control originally intends to drive the vehicle at a high vehicle speed. However, when the ACC is being executed, the host vehicle normally performs a curve deceleration control to travel along a curved road CR. The curve deceleration control decelerates the host vehicle so that the vehicle speed does not exceed an upper limit value of the yaw rate corresponding to the vehicle speed. Therefore, the vehicle speed at this time is normally constant regardless of the driver. Therefore, through the above-described learning, in the host vehicle where the curve deceleration control is being executed, if the driver has high driving ability and infrequent braking, the higher the set vehicle speed, the higher the upper limit value of the yaw rate corresponding to the vehicle speed, thereby increasing the vehicle speed during the curve deceleration control. By doing so, the cruise control unit 47 increases the vehicle speed of the host vehicle traveling along the curved road CR above the normally constant vehicle speed, thereby improving the comfort felt by a driver who intends to travel along the curved road CR at a high vehicle speed and has driving ability. Note that the above-described learning is performed when a preceding vehicle is detected, but not when a preceding vehicle is not detected.

[0063] FIG. 4 is a flowchart showing the contents of acceleration / deceleration control of the host vehicle when the host vehicle, in which ACC is being executed, travels on a curved road in the vehicle control device according to the embodiment of the present invention.

[0064] FIG. 5 is a flowchart showing the processes following connectors A and B in the flowchart of FIG.

[0065] FIG. 6 is a flowchart showing an alternative process to the process enclosed by the two-dot chain line P in FIG.

[0066] 4 to 6, the operation of the vehicle control device 10 according to the embodiment of the present invention described above (acceleration / deceleration control when the host vehicle, for which ACC is being executed, travels on a curved road CR) will be described. For ease of explanation, it is assumed that ACC is operating and that follow-cruise control or constant-speed cruise control is being executed on the host vehicle. The curved road CR on which the host vehicle and the preceding vehicle travel is comprised of a first clothoid section Sc1, a steady-state circle section Src, and a second clothoid section Sc2. The first position, i.e., the position of the host vehicle when the preceding vehicle, which had been detected up until that point, is no longer detected by the host vehicle in follow-cruise control, is assumed to be immediately before the entrance to the curved road CR.

[0067] As shown in Fig. 4, first, in step S1, the vehicle control device 10 determines whether the position of the host vehicle is near a curved road CR. If the position of the host vehicle is near a curved road CR (YES in step S1), the process proceeds to step S2. If the position of the host vehicle is not near a curved road CR (NO in step S1), step S1 is repeated and the vehicle waits until the position of the host vehicle is near the curved road CR. In other words, the vehicle control device 10 maintains the following cruise control or constant speed cruise control.

[0068] In step S2 following YES in step S1, the vehicle control device 10 determines whether a preceding vehicle is present. In other words, the vehicle control device 10 determines whether it is performing follow-up cruise control or constant speed cruise control. If a preceding vehicle is present (YES in step S2), the process proceeds to step S3, and if a preceding vehicle is not present (NO in step S2), the process proceeds to step S7. Note that a preceding vehicle is present when the vehicle control device 10 is performing follow-up cruise control, and a preceding vehicle is not present when the vehicle control device 10 is performing constant speed cruise control.

[0069] In step S3 following YES in step S2, the vehicle control device 10 determines whether the position of the vehicle is immediately before the entrance of the curved road CR. If the position of the vehicle is immediately before the entrance of the curved road CR (YES in step S3), the process proceeds to step S4. If the position of the vehicle is not immediately before the entrance of the curved road CR (NO in step S3), the process returns to step S2, and the determination in step S2 is repeated until the position of the vehicle is immediately before the entrance of the curve.

[0070] In step S4 following YES in step S3, the vehicle control device 10 determines whether or not it is necessary to decelerate the host vehicle. If it is necessary to decelerate the host vehicle (YES in step S4), the process proceeds to step S5, where the vehicle control device 10 performs pre-curve deceleration control. If it is not necessary to decelerate the host vehicle (NO in step S4), the process proceeds to step S6. An example of a case where deceleration is not necessary is when the curvature of the curved road CR that the host vehicle is about to enter is an excessively small, gentle curve.

[0071] In step S6 following step S4 (NO) or step S5, the vehicle control device 10 determines whether the preceding vehicle is no longer detected. If the preceding vehicle is no longer detected (YES in step S6), the process proceeds to step S10 in Fig. 5, and if the preceding vehicle has not been lost (NO in step S6), the process proceeds to step S24 in Fig. 5.

[0072] In step S7 following NO in step S2, the vehicle control device 10 determines whether the position of the vehicle is immediately before the entrance of the curved road CR. If the position of the vehicle is immediately before the entrance of the curved road CR (YES in step S7), the process proceeds to step S8. If the position of the vehicle is not immediately before the entrance of the curved road CR (NO in step S3), the process returns to step S2, and the determination in step S2 is repeated until the position of the vehicle is immediately before the entrance of the curved road CR.

[0073] In step S8 following YES in step S7, the vehicle control device 10 determines whether or not it is necessary to decelerate the host vehicle. If it is necessary to decelerate the host vehicle (YES in step S8), the process proceeds to step S9, where the vehicle control device 10 performs pre-curve deceleration control. If it is not necessary to decelerate the host vehicle (NO in step S8), the process proceeds to step S24 in Fig. 5. Note that, as in the case of NO in step S4, deceleration is not necessary when, for example, the curvature of the curved road CR that the host vehicle is about to enter is excessively small and the curve is gentle.

[0074] 5, in step S10 following YES in step S6 in Fig. 4, the vehicle control device 10 determines whether the lost position (second position) of the preceding vehicle is within the first clothoid section Sc1. If the lost position of the preceding vehicle is within the first clothoid section Sc1 (YES in step S10), the process proceeds to S11, and if the lost position of the preceding vehicle is not within the first clothoid section Sc1 (NO in step S10), the process proceeds to step S16.

[0075] In step S11 following the YES result in step S10, the vehicle control device 10 decelerates the host vehicle at the deceleration rate of the preceding vehicle just before the lost position.

[0076] In step S12 following step S11, the vehicle control device 10 determines whether the curved road CR on which the host vehicle is traveling is a steady circle section Src. If the curved road CR on which the host vehicle is traveling is a steady circle section Src (YES in step S12), the process proceeds to step S13. If the curved road CR on which the host vehicle is traveling is not a steady circle section Src (NO in step S12), the process of step S11 is continued until the curved road CR on which the host vehicle is traveling becomes a steady circle section Src.

[0077] Here, the processing of steps S11 and S12 enclosed by a two-dot chain line P in Fig. 5 can be replaced with steps S31 and S32 enclosed by a two-dot chain line P', which are alternative processing shown in Fig. 6. The processing of steps S31 and S32, which are performed instead of the processing of steps S11 and S12, will be described below with reference to Fig. 6.

[0078] In step S31 following YES in step S10, the vehicle control device 10 compares the deceleration of the preceding vehicle immediately before the lost position with the deceleration set in the pre-curve deceleration control, and decelerates the vehicle at the larger deceleration.

[0079] In step S32 following step S31, the vehicle control device 10 determines whether the curved road CR on which the host vehicle is traveling is a steady circle section Src. If the curved road CR on which the host vehicle is traveling is a steady circle section Src (YES in step S32), the process proceeds to step S13. If the curved road CR on which the host vehicle is traveling is not a steady circle section Src (NO in step S32), the process of step S31 is continued until the curved road CR on which the host vehicle is traveling becomes a steady circle section Src.

[0080] 5, in step S13 following a YES in step S12 or a YES in step S32 when steps S31 and S32 are performed instead of steps S11 and S12, the vehicle control device 10 causes the host vehicle to travel at a constant speed. That is, the vehicle control device 10 performs acceleration / deceleration control of the host vehicle so that the host vehicle maintains a constant speed.

[0081] In step S14 following step S13, the vehicle control device 10 determines whether the vehicle is at the exit of the curved road CR. If the vehicle is at the exit of the curved road CR (YES in step S14), the process proceeds to step S15, and if the vehicle is not at the exit of the curved road CR (NO in step S14), the process of step S13 is continued until the vehicle reaches the exit of the curved road CR. In other words, the constant speed traveling of the vehicle continues from the steady circle section Src of the curved road CR to the exit of the curved road CR.

[0082] The series of processes from YES in step S10 to YES in step S14 is the first clothoid section target lost control described above. Also, the series of processes from YES in step S10 to YES in steps S31, S32, S13, and S14 is a modified example of the first clothoid section target lost control described above.

[0083] In step S15 following the YES result in step S14, the vehicle control device 10 resumes the follow-up cruise control or constant speed cruise control of the host vehicle.

[0084] In step S16 following NO in step S10, the vehicle control device 10 determines whether the lost position of the preceding vehicle is within the steady circle section Src. If the lost position of the preceding vehicle is within the steady circle section Src (YES in step S16), the process proceeds to step S17, and if the lost position of the preceding vehicle is not within the steady circle section Src (NO in step S16), the process proceeds to step S19.

[0085] In step S17 following the YES result in step S16, the vehicle control device 10 performs pre-curve deceleration control.

[0086] In step S18 following step S17, the vehicle control device 10 determines whether the curved road CR on which the vehicle is traveling is a steady circle section Src. If the curved road CR on which the vehicle is traveling is a steady circle section Src (YES in step S18), the process proceeds to step S13, and the process of step S13 is performed. If the curved road CR on which the vehicle is traveling is not a steady circle section Src (NO in step S15), the process of step S17 is continued until the curved road CR on which the vehicle is traveling becomes a steady circle section Src. The series of processes from YES in step S16, to step S17, to YES in step S18, to YES in steps S13 and S14, is the steady circle section target lost control described above.

[0087] In step S19 following NO in step S16, the vehicle control device 10 determines whether the lost position of the preceding vehicle is within the second clothoid section Sc2. If the lost position of the preceding vehicle is within the second clothoid section Sc2 (YES in step S19), the process proceeds to step S20, and if the lost position of the preceding vehicle is not within the second clothoid section Sc2 (NO in step S19), the process proceeds to step S24. Note that if the lost position of the preceding vehicle is not within the second clothoid section Sc2 (NO in step S19), this means that the lost position of the preceding vehicle is within the straight road SR that continues to the exit of the curved road CR.

[0088] In step S20 following the YES result in step S19, the vehicle control device 10 performs pre-curve deceleration control.

[0089] In step S21 following step S20, the vehicle control device 10 determines whether or not the host vehicle has reached the steady circle section Src. If the host vehicle has reached the steady circle section Src (YES in step S21), the process proceeds to step S22. If the host vehicle has not reached the steady circle section Src (NO in step S21), the process of step S20 is continued until the host vehicle reaches the steady circle section Src. The series of processes from YES in step S19 to YES in S21 is the curve exit section target lost control described above.

[0090] In step S22 following the YES result in step S21, the vehicle control device 10 causes the host vehicle to travel at a constant speed.

[0091] In S23 following S22, the vehicle control device 10 determines whether the path length from the vehicle to the second clothoid section Sc2 has reached the predetermined path length Lp, which becomes shorter as the radius of curvature of the steady circle section Src becomes smaller. If the path length to the second clothoid section Sc2 has reached the predetermined path length Lp (YES in step S23), the process proceeds to step S15 and performs the processing of step S15. If the path length to the second clothoid section Sc2 has not reached the predetermined path length Lp (NO in step S23), the process returns to step S22 and continues the processing of step S22.

[0092] In step S24 following a NO in step S6 in Fig. 4, a NO in step S8 in Fig. 4, a NO in step S9 in Fig. 4, or a NO in S19, the vehicle control device 10 performs deceleration control while traveling around a curve to decelerate the host vehicle to a vehicle speed based on learning. This deceleration control while traveling around a curve is the learning-type deceleration control while traveling around a curve described above.

[0093] In step S25 following step S24, the vehicle control device 10 determines whether the vehicle is at the exit of the curved road CR. If the vehicle is at the exit of the curved road CR (YES in step S25), the process proceeds to step S15 and performs the process of step S15. If the vehicle is not at the exit of the curved road CR (NO in step S25), the process of step S24 is continued until the vehicle reaches the exit of the curved road CR.

[0094] After executing the process of step S15, the vehicle control device 10 ends the current control.

[0095] According to the control flows shown in Figures 4 to 6, when a vehicle in which ACC is being executed travels on a curved road CR, the vehicle control device 10 enables comfortable acceleration / deceleration control of ACC for the driver even when the vehicle in front as a vehicle to be followed cannot be detected.

[0096] As described above, the vehicle control device 10 according to this embodiment includes a cruise control unit 47 that, when a preceding vehicle is no longer detected while the host vehicle is traveling on a curved road CR in which follow-up cruise control is being executed, switches the acceleration / deceleration of the host vehicle based on a first position, which is the location of the host vehicle when the preceding vehicle is no longer detected, and a second position, which is the location of the preceding vehicle when the preceding vehicle is no longer detected. Therefore, unlike conventional vehicle cruise control devices equipped with an ACC device, when a preceding vehicle to be followed is no longer detected while the host vehicle is traveling on a curved road CR in which follow-up cruise control, i.e., ACC, is being executed, the vehicle control device 10 can achieve acceleration / deceleration in the host vehicle similar to the acceleration / deceleration of the vehicle according to each section of the curved road CR when the driver is manually driving the vehicle. Therefore, even when a preceding vehicle to be followed is no longer detected while the host vehicle is traveling on a curved road CR in which ACC is being executed, the vehicle control device 10 can perform ACC acceleration / deceleration control that is comfortable and does not feel strange to the driver.

[0097] Furthermore, the vehicle control device 10 according to this embodiment includes a cruise control unit 47 that, when the first position is immediately before the entrance to the curved road CR and the second position is within the first clothoid section Sc1, causes the host vehicle to decelerate at the deceleration of the preceding vehicle immediately before the second position until the host vehicle reaches the steady circle section Src. Therefore, the vehicle control device 10 can suppress the host vehicle from approaching the preceding vehicle, which may intimidate the driver, and improve the comfort felt by the driver when the host vehicle, with ACC being executed, travels on the curved road CR.

[0098] Furthermore, the vehicle control device 10 according to this embodiment includes a cruise control unit 47 that, when the first position is immediately before the entrance to the curved road CR and the second position is within the first clothoid section Sc1, causes the host vehicle to decelerate at the larger of the deceleration of the preceding vehicle immediately before the second position and the deceleration in the pre-curve deceleration control until the host vehicle reaches the steady circle section Src. Therefore, even if the preceding vehicle that is no longer detected is actually traveling on the curved road CR at a high vehicle speed without excessive deceleration, the vehicle control device 10 can cause the host vehicle, with ACC being executed, to travel on the curved road CR while giving the driver a sense of security.

[0099] Furthermore, the vehicle control device 10 according to this embodiment includes a cruise control unit 47 that causes the host vehicle to cruise at a constant speed when the position of the host vehicle while traveling is within the steady circle section Src. Therefore, the vehicle control device 10 suppresses acceleration control of the host vehicle when the preceding vehicle is no longer detected and the constant speed cruise mode (constant speed cruise control) of the ACC is enabled, and can further improve the comfort felt by the driver when the host vehicle with ACC running travels on a curved road CR.

[0100] Furthermore, the vehicle control device 10 according to this embodiment includes a cruise control unit 47 that, when the first position is immediately before the entrance to the curved road CR and the second position is in the steady circle section Src, performs pre-curve deceleration control until the host vehicle reaches the steady circle section Src, and causes the host vehicle to travel at a constant speed when the host vehicle is located within the steady circle section Src during travel. Therefore, when the host vehicle in which ACC is being executed enters a curved road CR, the vehicle control device 10 can prevent the host vehicle from approaching a preceding vehicle by pre-curve deceleration control, thereby providing the driver with a sense of security. Furthermore, the vehicle control device 10 can further improve the comfort felt by the driver by causing the host vehicle to travel at a constant speed within the steady circle section Src to prevent the host vehicle from approaching a preceding vehicle and unnecessary deceleration of the host vehicle.

[0101] Furthermore, the vehicle control device 10 according to this embodiment includes a cruise control unit 47 that performs pre-curve deceleration control until the host vehicle reaches the steady circle section Src when the first position is immediately before the entrance to the curved road CR and the second position is within the second clothoid section Sc2. Therefore, when the host vehicle with ACC running enters the curved road CR, the vehicle control device 10 can prevent the host vehicle from approaching the preceding vehicle by performing pre-curve deceleration control, thereby providing the driver with a sense of security. Furthermore, even if the vehicle control device 10 accelerates the host vehicle after reaching the steady circle section Src, the preceding vehicle that is no longer detected in the second clothoid section Sc2 is likely to accelerate thereafter. This can reduce the driver's sense of fear that may arise when the host vehicle approaches the preceding vehicle. Therefore, the vehicle control device 10 can further improve the comfort felt by the driver when the host vehicle with ACC running travels on the curved road CR.

[0102] Furthermore, the vehicle control device 10 according to this embodiment includes a cruise control unit 47 that, when the first position is immediately before the entrance to the curved road CR and the second position is within the second clothoid section Sc2, causes the host vehicle to travel at a constant speed in the steady circle section Src until the path length from the host vehicle to the second clothoid section Sc2 reaches a predetermined path length Lp, which becomes shorter as the radius of curvature of the steady circle section Src becomes smaller. Therefore, while the host vehicle is traveling at a constant speed in the steady circle section Src with ACC being executed, the vehicle control device 10 can cause the host vehicle to travel at a constant speed up to a position where the driver is expected to accelerate the host vehicle, and then place the host vehicle in a state where it can be accelerated. Therefore, the vehicle control device 10 can further improve the comfort felt by the driver when the host vehicle is traveling on a curved road CR with ACC being executed.

[0103] Furthermore, the vehicle control device 10 according to this embodiment includes a driving control unit 47 that, when the host vehicle is traveling on a curved road CR having a curvature radius equal to or less than a predetermined value and the preceding vehicle is no longer detected, reduces the vehicle speed of the host vehicle during deceleration control while traveling on a curve compared to when the preceding vehicle is detected. Therefore, even when the host vehicle, for which ACC is being executed, is traveling on a sharply curved road CR having a curvature radius equal to or less than a predetermined value, the vehicle control device 10 decelerates the host vehicle to a vehicle speed that is slower than the vehicle speed when traveling on a normal curved road CR having a curvature radius exceeding the predetermined value, thereby giving the driver a sense of security and further improving the comfort felt by the driver.

[0104] Furthermore, the vehicle control device 10 according to this embodiment includes a cruise control unit 47 that, when a preceding vehicle is detected while performing deceleration control for a curve, learns the relationship between the curvature of the curved road CR, the set vehicle speed for constant speed cruise control, and whether or not the driver brakes the host vehicle. If, as a result of learning, the cruise control unit 47 performs deceleration control for a curved road CR with a curvature where the frequency of braking was low, the higher the set vehicle speed, the higher the upper limit of the yaw rate corresponding to the host vehicle's speed, thereby increasing the host vehicle speed during deceleration control for a curve. Therefore, when the host vehicle is running ACC including adaptive cruise control or constant speed cruise control on a curved road CR, the vehicle control device 10 can improve the comfort felt by a driver with high driving ability who wishes to drive the vehicle at a high speed.

[0105] Therefore, according to the vehicle control device 10 of this embodiment, when a vehicle in which ACC is being executed is traveling on a curved road CR, even if the vehicle in front as a vehicle to be followed can no longer be detected, acceleration and deceleration control of ACC that is comfortable for the driver is possible.

[0106] Although several embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be embodied in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included within the scope and spirit of the invention, and are also included in the scope of the invention and its equivalents as defined in the claims. [Explanation of symbols]

[0107] 1...on-vehicle sensor, 3...on-vehicle navigation device, 5...accelerator control device, 7...brake control device, 8...ACC switch, 9...ACC setting switch, 10...vehicle control device, 21...camera sensor, 22...radar sensor, 23...wheel speed sensor, 24...acceleration sensor, 25...yaw rate sensor, 31...GNSS receiver, 33...map information, 41...ACC determination unit, 43...preceding vehicle detection unit, 45...curve detection unit, 46...yaw rate determination unit, 47...driving control unit, 100...vehicle control system, CR...curved road, Lp...predetermined route length, R...road, Sc1...first clothoid section, Sc2...second clothoid section, Src...steady circle section, SR...straight road.

Claims

1. a preceding vehicle detection unit that detects a preceding vehicle; a curve detection unit that detects a curve from a road in the traveling direction of the vehicle; a driving control unit that controls driving of the host vehicle based on detection results of the preceding vehicle detection unit and the curve detection unit, The traveling control unit When the preceding vehicle is detected, a following running control is performed to make the host vehicle follow the preceding vehicle within a set inter-vehicle time; When the preceding vehicle is not detected, constant speed travel control is performed to make the host vehicle travel at a set vehicle speed; When the curved road is detected while the following cruise control or the constant speed cruise control is being performed, a pre-curve deceleration control is performed to decelerate the host vehicle immediately before the entrance of the curved road, When the vehicle undergoing the following cruise control travels along the curve and the preceding vehicle is no longer detected, the vehicle control device switches the acceleration / deceleration of the vehicle based on a first position, which is the position of the vehicle obtained from the detection results of the curve detection unit and is the position of the vehicle when the preceding vehicle is no longer detected, and a second position, which is the position of the preceding vehicle when the preceding vehicle is no longer detected.

2. 2. The vehicle control device according to claim 1, wherein, when the first position is immediately before the entrance to the curved road and the second position is within a first clothoid section, which is part of the curved road and where the curvature gradually increases until it reaches a constant value, the driving control unit decelerates the vehicle at the deceleration of the preceding vehicle immediately before the second position until the vehicle reaches a steady circle section, which is part of the curved road and where the curvature reaches the constant value.

3. 2. The vehicle control device of claim 1, wherein when the first position is immediately before the entrance to the curved road and the second position is within a first clothoid section, which is part of the curved road and where the curvature gradually increases until it reaches a constant value, the driving control unit decelerates the vehicle at a larger deceleration of the deceleration of the preceding vehicle immediately before the second position and the deceleration in the pre-curve deceleration control, until the vehicle reaches a steady circle section, which is part of the curved road and where the curvature reaches the constant value.

4. The vehicle control device according to claim 2 or 3, wherein the travel control unit causes the host vehicle to travel at a constant speed when the host vehicle is positioned within the steady-state circular section during travel.

5. The traveling control unit When the first position is immediately before the entrance of the curved road and the second position is a steady circular section that is a part of the curved road and is a section where the curvature is a constant value, the pre-curve deceleration control is performed until the host vehicle reaches the steady circular section, The vehicle control device according to any one of claims 1 to 3, wherein when the position of the host vehicle during travel is within the steady-state circular section, the host vehicle is caused to travel at a constant speed.

6. A vehicle control device as described in any one of claims 1 to 3, wherein when the first position is immediately before the entrance to the curved road and the second position is within a second clothoid section which is part of the curved road and where the curvature gradually decreases from a constant value, the driving control unit performs the pre-curve deceleration control until the vehicle reaches a steady circle section which is part of the curved road and where the curvature becomes the constant value.

7. 7. The vehicle control device according to claim 6, wherein, when the first position is immediately before the entrance to the curved road and the second position is within the second clothoid section, the driving control unit causes the vehicle to travel at a constant speed in the steady circular section until a path length from the vehicle to the second clothoid section becomes a predetermined path length that becomes shorter as the radius of curvature of the steady circular section becomes smaller.

8. a yaw rate determination unit that determines whether a yaw rate generated in the host vehicle while traveling on the curved road exceeds an upper limit value according to a vehicle speed of the host vehicle, The traveling control unit performing a deceleration control during curve traveling in which the host vehicle decelerates based on the determination result of the yaw rate determination unit so that the yaw rate does not exceed the upper limit value corresponding to the vehicle speed of the host vehicle; 2. The vehicle control device according to claim 1, wherein when the preceding vehicle is no longer detected while the vehicle is traveling on the curved road having a curvature radius equal to or less than a predetermined value, the vehicle speed of the vehicle during the deceleration control while traveling on the curve is made lower than when the preceding vehicle is detected.

9. The traveling control unit When the preceding vehicle is detected while the deceleration control is being performed while traveling around a curve, the system learns the relationship between the curvature of the curve, the set vehicle speed of the constant speed traveling control, and whether or not the driver has applied the brakes to the host vehicle, 9. The vehicle control device according to claim 8, wherein, as a result of the learning, when the deceleration control during curve driving is performed again on the curved road having the curvature where the frequency of the brake operation was low, the upper limit value of the yaw rate corresponding to the vehicle speed of the host vehicle is increased as the set vehicle speed is higher, thereby increasing the vehicle speed of the host vehicle during the deceleration control during curve driving.

Images