Vehicle control system

Abstract

This vehicle control device provides a vehicle control system that prevents acceleration delays during vehicle acceleration in ACC (Adaptive Cruise Control) mode, thereby achieving a superior acceleration feel. [Solution] The vehicle control device 1 includes an ambient detection unit 3, a drive source control unit 7, an automatic transmission 11, a gear shift control unit 13 that controls the automatic transmission 11, a vehicle speed acquisition unit 32, a preceding vehicle detection unit 33, and a driving control unit 35 that changes the requested acceleration to the drive source control unit 7 in both follow driving control, which makes the vehicle follow a preceding vehicle, and constant speed driving control, which makes the vehicle drive at a constant speed. The driving control unit 35, when the actual acceleration of the vehicle when a downshift is performed during acceleration at a predetermined vehicle speed in manual driving, where follow driving control and constant speed driving control are not performed, is defined as the downshift acceleration during manual driving, causes the automatic transmission 11 to perform a downshift via the gear shift control unit 13 in a predetermined situation where the requested acceleration is smaller than the downshift acceleration during manual driving at a predetermined vehicle speed.

Description

Technical Field

[0001] Embodiments according to the present invention relate to a vehicle control device.

Background Art

[0002] There is known a vehicle control device for optimally driving an autonomous vehicle when an inhibition of an action plan is temporary. The vehicle control device includes a surrounding situation detection unit that detects the surrounding situation of the autonomous vehicle, an action plan generation unit that generates an action plan including a target trajectory of the autonomous vehicle based on the surrounding situation detected by the surrounding situation detection unit, and a travel control unit that controls a travel unit so that the autonomous vehicle travels in autonomous driving according to the action plan generated by the action plan generation unit. The vehicle control device can perform follow-up driving following a preceding vehicle and cruise driving at a predetermined speed, that is, constant speed driving. The travel control that enables follow-up driving and constant speed driving may be referred to as Adaptive Cruise Control (ACC).

[0003] Also, even when an inhibition of an action plan in an autonomous vehicle is temporary, for example, changes in the vehicle state associated with upshifting and downshifting of a transmission frequently occur, and smooth driving of the autonomous vehicle may be hindered. Therefore, the vehicle control device has an acceleration plan for performing downshifting for optimal autonomous driving.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] Incidentally, vehicles using ACC (Adaptive Cruise Control) may automatically accelerate if the preceding vehicle, which is being followed, moves out of its lane, for example, by changing lanes.

[0006] However, during this acceleration process, a downshift occurs in the vehicle while it is accelerating, causing a delay in the vehicle's acceleration. As a result, the driver of the vehicle cannot experience a smooth acceleration feeling.

[0007] Therefore, the present invention aims to provide a vehicle control device that can prevent acceleration delays and achieve an excellent acceleration feeling when accelerating a vehicle in ACC mode. [Means for solving the problem]

[0008] To solve the aforementioned problems, a vehicle control device according to an embodiment of the present invention includes: an ambient detection unit that detects objects present around the vehicle; a drive source control unit that controls a drive source that generates the propulsion force of the vehicle; an automatic transmission that changes the speed of the vehicle; a gear shift control unit that controls the automatic transmission; a vehicle speed acquisition unit that acquires the vehicle speed of the vehicle; a preceding vehicle detection unit that detects a preceding vehicle traveling in front of the vehicle's lane based on the detection results of the ambient detection unit; a driving control unit that, when the preceding vehicle detection unit detects the preceding vehicle, performs follow-up driving control to make the vehicle follow the preceding vehicle for a set interval; when the preceding vehicle detection unit does not detect the preceding vehicle, performs constant-speed driving control to make the vehicle travel at a set speed; and changes the requested acceleration to the drive source control unit in both the follow-up driving control and the constant-speed driving control depending on the situation. The driving control unit, when the actual acceleration of the vehicle during manual driving when accelerating at a predetermined vehicle speed in manual driving where the follow driving control and the constant speed driving control are not being performed is defined as the manual driving downshift acceleration, causes the gear shift control unit to control the automatic transmission to perform a downshift in a predetermined situation where the required acceleration is smaller than the manual driving downshift acceleration at the predetermined vehicle speed. [Effects of the Invention]

[0009] The present invention provides a vehicle control device that can prevent acceleration delays during vehicle acceleration in ACC mode, thereby achieving an excellent acceleration feel. [Brief explanation of the drawing]

[0010] [Figure 1] A schematic diagram showing the configuration of a vehicle control device according to an embodiment of the present invention. [Figure 2] A timing chart showing the time-series behavior of a vehicle equipped with a conventional vehicle control system during gear changes. [Figure 3] A timing chart showing the time-series behavior of a vehicle equipped with a vehicle control device according to an embodiment of the present invention during gear shifting. [Figure 4] This figure shows an example of determining when a preceding vehicle will leave the vehicle during downshift acceleration control using a vehicle control device according to an embodiment of the present invention. [Figure 5] A flowchart showing an example of the processing procedure for downshift acceleration control by a vehicle control device according to an embodiment of the present invention. [Figure 6] A flowchart showing an example of an alternative process for the process enclosed by the dashed line A in Figure 5. [Figure 7] A flowchart showing another example of an alternative process for the process enclosed by the dashed line A in Figure 5. [Modes for carrying out the invention]

[0011] An embodiment of the vehicle control device according to the present invention will be described with reference to Figures 1 to 7.

[0012] Figure 1 is a schematic diagram showing the configuration of a vehicle control device according to an embodiment of the present invention.

[0013] The vehicle control device 1 shown in Figure 1 is a type of automated driving system that provides timely adaptive cruise control (ACC) to a vehicle equipped with the vehicle control device 1 to assist the driver. Driving assistance means that the automated driving system automatically performs at least one of the following operations, limited and continuous: acceleration and deceleration of the vehicle, including starting and stopping the vehicle, and steering the vehicle.

[0014] Furthermore, the vehicle control device 1 is applicable not only to engine-powered vehicles but also to electric vehicles, hybrid vehicles, fuel cell vehicles, and other types of vehicles. Hereinafter, a vehicle equipped with the vehicle control device 1 will be referred to as "our vehicle."

[0015] ACC (Adaptive Cruise Control) detects a preceding vehicle in the same lane as the vehicle currently traveling in and causes the vehicle to follow the preceding vehicle for a preset distance. In other words, ACC automatically accelerates and decelerates the vehicle within a preset speed to bring the vehicle closer to the preceding vehicle by a predetermined distance and maintain this distance. This type of follow-up driving by ACC may be referred to as "follow-up driving mode" below. Furthermore, if no preceding vehicle is detected, ACC maintains a constant speed at a preset speed. This type of constant speed driving by ACC may be referred to as "constant speed driving mode" below. With ACC, the driver can operate the vehicle without pressing the accelerator or brake pedal except when necessary. In this embodiment, "preceding vehicle" may refer not only to a vehicle in front of the vehicle in the same lane as the vehicle, but also to a vehicle in front of the vehicle in an adjacent lane adjacent to the vehicle's lane.

[0016] The vehicle control device 1 will be described in detail below with reference to Figure 1.

[0017] As shown in FIG. 1, the vehicle control device 1 according to the present embodiment includes a peripheral detection unit 3, a wheel speed sensor 5, a drive source control unit 7, a brake control unit 9, an automatic transmission 11, a shift control unit 13, an ACC switch 15, an ACC setting switch 16, a Human Machine Interface (HMI) device 17, and an ACC controller 18. The wheel speed sensor 5, the drive source control unit 7, the brake control unit 9, the shift control unit 13, the ACC switch 15, the ACC setting switch 16, the HMI device 17, and the ACC controller 18 are communicably connected to each other via an in-vehicle network 19. The in-vehicle network 19 is, for example, a bus-type network that uses CAN (Controller Area Network) as a communication protocol. Further, the peripheral detection unit 3 and the ACC controller 18 are connected by, for example, a serial communication line different from the in-vehicle network 19. Also, the wheel speed sensor 5 may be connected to the brake control unit 9 and connected to the in-vehicle network 19 via the brake control unit 9.

[0018] The peripheral detection unit 3 acquires target information around the host vehicle and transmits it to the ACC controller 18. The peripheral detection unit 3 includes a camera sensor 21 and a radar sensor 22.

[0019] The camera sensor 21 captures an image in front of the host vehicle, acquires an image of an object existing in front of the host vehicle and its surroundings, and generates image information. The camera sensor 21 includes an image processing unit (not shown) that acquires object information including, for example, the distance from the host vehicle to the object and the orientation of the object with respect to the host vehicle from the generated image information. Also, the camera sensor 21 transmits the generated image information to the ACC controller 18. The camera sensor 21 is attached to the windshield, the back surface of the rearview mirror, or the front head of the vehicle body in order to capture the front.

[0020] The radar sensor 22 acquires object information including, for example, the distance from the host vehicle to an object that reflects the probing wave and the orientation of the object with respect to the host vehicle based on the result of transmitting and receiving the probing wave. Specifically, the radar sensor 22 in the present embodiment is a millimeter-wave radar sensor that uses radio waves in the millimeter-wave band as the probing wave, scans in a range of a predetermined angle in front of the host vehicle, outputs the result, and detects the reflected wave. Then, the radar sensor 22 can obtain, as the position of the object from the host vehicle, the distance from the host vehicle to the object from the time required for the millimeter wave to travel back and forth between the object that reflects the millimeter wave, and the angle data representing the orientation where the object that reflects the millimeter wave exists. Note that the radar sensor 22 is not limited to a millimeter-wave radar sensor, and may be a lidar sensor that uses laser light as the probing wave or a sonar radar sensor that uses ultrasonic waves as the probing wave. Further, the radar sensor 22 may use two or more types of these radar sensors.

[0021] The wheel speed sensor 5 is provided on each wheel of the host vehicle and detects the rotational speed of the wheel. Based on the wheel speed detected by the wheel speed sensor 5, it is possible to detect the traveling speed of the host vehicle, that is, the vehicle speed. The wheel speed sensor 5 transmits the detected wheel speed to the ACC controller 18 and the shift control unit 13.

[0022] The drive source control unit 7 controls an engine and / or an electric motor, which are not shown, as the drive source that generates the driving force of the host vehicle based on the acceleration request transmitted from the ACC controller 18, that is, the acceleration request signal representing the requested acceleration. Further, when the host vehicle is traveling by ACC, the drive source control unit 7 transmits a virtual accelerator opening degree, which is a signal calculated from the rotational speed and torque of the drive source, to the shift control unit 13.

[0023] The virtual accelerator opening typically increases as the requested acceleration from the ACC controller 18 increases. Furthermore, if the drive source includes both an engine and an electric motor, the vehicle is a hybrid vehicle. Also, if the drive source includes an electric motor, the vehicle is equipped with a battery to supply power to the electric motor.

[0024] The brake control unit 9 controls the brakes (not shown) that generate braking force for the vehicle based on the deceleration request signal, which represents the deceleration degree request transmitted from the ACC controller 18.

[0025] The automatic transmission 11 changes the vehicle's speed. In other words, the automatic transmission 11 changes the speed of the rotation output from the drive source. A drive shaft (not shown), which has drive wheels (not shown) at both ends, is connected to the output shaft of the automatic transmission 11 via, for example, a differential gear (not shown), and the changed speed is transmitted to the drive wheels to drive them.

[0026] The gear shift control unit 13 transmits a gear shift request signal to the automatic transmission 11 based on, for example, virtual accelerator opening information transmitted from the drive source control unit 7 and wheel speed information transmitted from the wheel speed sensor 5, thereby enabling optimal gear shift control in the automatic transmission 11. Normally, the gear shift control unit 13 performs a downshift when the virtual accelerator opening exceeds a predetermined threshold.

[0027] The predetermined threshold for the virtual throttle opening that triggers a downshift differs depending on the gear combination before and after the downshift. In other words, the predetermined threshold for the virtual throttle opening when downshifting from 6th gear to 5th gear will be different from the predetermined threshold for the virtual throttle opening when downshifting from 5th gear to 4th gear.

[0028] The ACC switch 15 is located near the driver's seat and is operated by the driver. The ACC switch 15 is operated when the driver requests to start or stop the ACC. When the ACC switch 15 is turned ON by the driver when the ACC is not operating, it sends an ACC start request signal to the ACC controller 18, indicating that the driver is requesting to start the ACC. On the other hand, when the ACC switch 15 is turned OFF by the driver when the ACC is operating, it sends an ACC end request signal to the ACC controller 18, indicating that the driver is requesting to stop the ACC.

[0029] The ACC setting switch 16 is located near the ACC switch 15 and is operated by the driver. The ACC setting switch 16 is operated when the driver sets the set interval time and the set speed. The set interval time is the interval time that the vehicle maintains between itself and the preceding vehicle in the ACC follow-me driving mode. The set speed is the speed that the vehicle maintains in the ACC constant speed driving mode. Alternatively, instead of setting the set interval time, the configuration may be such that the set distance is calculated by multiplying the set interval time by the speed. When the ACC setting switch 16 is operated and the set interval time and set speed are set, the ACC setting switch 16 transmits setting signals representing the set interval time and set speed to the ACC controller 18.

[0030] The HMI device 17 is a notification device that presents various information to the vehicle occupants. The HMI device 17 accepts input operations from the occupants. The HMI device 17 includes, for example, a display, speaker, touch panel, switches, and keys (not shown in the figure). The HMI device 17 may be configured to display various information related to ACC on the display or to notify users by voice (sound) via the speaker in response to control signals transmitted from the ACC controller 18.

[0031] The ACC controller 18 is configured as a computer equipped with a central processing unit (CPU), an input / output interface, and storage devices such as ROM and RAM. When the ACC controller 18 receives information from the surrounding detection unit 3 and the wheel speed sensor 5, an ACC start request signal and an ACC end request signal from the ACC switch 15, and a setting signal from the ACC setting switch 16, it performs predetermined calculations related to vehicle driving control and transmits control signals corresponding to the results to the drive source control unit 7 and the brake control unit 9. The control signals are an acceleration request signal to the drive source control unit 7 and a deceleration request signal to the brake control unit 9.

[0032] The ACC controller 18 includes, for example, an ACC determination unit 31, a vehicle speed acquisition unit 32, a preceding vehicle detection unit 33, and a driving control unit 35. The ACC controller 18 may further include a first turn signal operation determination unit 36 ​​and a second turn signal operation determination unit 37.

[0033] The ACC determination unit 31 determines whether the ACC switch 15 is ON or OFF. Specifically, when the ACC switch 15 is ON and the ACC determination unit 31 receives an ACC start request signal from the ACC switch 15, it changes the ACC operation flag from OFF to ON. On the other hand, when the ACC switch 15 is turned OFF by the driver and the ACC determination unit 31 receives an ACC end request signal from the ACC switch 15, it changes the ACC operation flag from ON to OFF.

[0034] The vehicle speed acquisition unit 32 receives wheel speed information transmitted from the wheel speed sensor 5 and calculates and acquires the vehicle speed of the vehicle. The actual acceleration of the vehicle can be obtained by differentiating the acquired vehicle speed.

[0035] When the ACC operation flag is turned ON, the preceding vehicle detection unit 33 performs preceding vehicle detection processing to identify and detect a preceding vehicle located in front of the vehicle's lane, based on object information and image information transmitted from the camera sensor 21 and object information transmitted from the radar sensor 22. If a preceding vehicle is detected by the preceding vehicle detection processing, the preceding vehicle detection unit 33 makes the preceding vehicle information, including the distance and direction from the vehicle to the preceding vehicle, as well as the vehicle speed and deceleration of the preceding vehicle, available for reference from the driving control unit 35.

[0036] Furthermore, if the detected preceding vehicle leaves its lane due to a lane change or other reason, the preceding vehicle detection unit 33 changes the preceding vehicle departure flag from OFF to ON, indicating that the preceding vehicle has left its lane. The preceding vehicle departure flag changes back from ON to OFF relatively quickly after being turned ON.

[0037] Furthermore, the preceding vehicle detection unit 33 detects the speed at which the detected preceding vehicle crosses the lane markings when it leaves the vehicle's lane due to a lane change or other reason. The preceding vehicle detection unit 33 switches the departure speed determination flag from OFF to ON when the speed at which the preceding vehicle crosses the lane markings exceeds a certain speed. In other words, the ON state of the departure speed determination flag indicates that the speed at which the preceding vehicle crosses the lane markings exceeds a certain speed. Also, at the moment the departure speed determination flag is switched from OFF to ON, the preceding vehicle detection unit 33 stores the position of the rear end of the preceding vehicle located in front of the vehicle's lane. Then, when the vehicle reaches this reversed position, the preceding vehicle detection unit 33 switches the arrival flag from OFF to ON.

[0038] When the ACC operation flag is turned ON and the preceding vehicle information that has become available to the preceding vehicle detection unit 33, i.e., the detection result of the preceding vehicle detection unit 33, is detected, the driving control unit 35 performs follow-up driving control to make the vehicle follow the preceding vehicle for a set interval time set in advance in the ACC setting switch 16. This follow-up driving control by the driving control unit 35 is the follow-up driving mode of ACC. Also, when the ACC operation flag is turned ON and no preceding vehicle is detected, the driving control unit 35 performs constant-speed driving control to make the vehicle drive at a set speed set in advance in the ACC setting switch 16. This constant-speed driving control by the driving control unit 35 is the constant-speed driving mode of ACC. In order to perform follow-up driving control and constant-speed driving control, the driving control unit 35 controls the acceleration and deceleration of the vehicle by sending an acceleration request signal to the drive source control unit 7 or a deceleration request signal to the brake control unit 9 in a timely manner. In other words, the driving control unit 35 changes the requested acceleration to the drive source control unit 7 and the requested deceleration to the brake control unit 9 in both follow-driving control and constant-speed driving control, depending on the situation.

[0039] When the ACC operation flag is turned ON, the first turn signal operation determination unit 36 ​​performs a first turn signal operation determination process based on object information and image information transmitted from the camera sensor 21 to determine whether the preceding vehicle detected by the preceding vehicle detection unit 33 has activated the turn signal on the side that is leaving the vehicle's lane. If the first turn signal operation determination process determines that the preceding vehicle traveling in the vehicle's lane has activated the turn signal on the side that is leaving the vehicle's lane, the first turn signal operation determination unit 36 ​​changes the first turn signal operation determination flag from OFF to ON.

[0040] When the ACC operation flag is turned ON, the second turn signal operation determination unit 37 performs a second turn signal operation determination process based on object information and image information transmitted from the camera sensor 21 to determine whether a preceding vehicle traveling in an adjacent lane adjacent to the vehicle's own lane has activated its turn signal on the vehicle's own lane. If the second turn signal operation determination process determines that a preceding vehicle traveling in an adjacent lane has activated its turn signal on the vehicle's own lane, the second turn signal operation determination flag, which is different from the first turn signal operation determination flag, is turned ON from OFF.

[0041] The driving control unit 35 constantly monitors the status of the preceding vehicle departure flag, departure speed determination flag, arrival flag, first turn signal operation determination flag, and second turn signal operation determination flag.

[0042] Figure 2 is a timing chart showing the time-series behavior of a vehicle equipped with a conventional vehicle control system during gear changes. Note that the time changes in gear position, vehicle speed, virtual accelerator opening, acceleration, and the preceding vehicle departure flag shown in Figure 2 are approximate and merely an example to facilitate understanding of the following explanation. The same applies to Figure 3, which will be explained later.

[0043] As mentioned above, in vehicles equipped with conventional vehicle control systems, that is, vehicles that use ACC (Adaptive Cruise Control), if the preceding vehicle being followed leaves its lane, for example due to a lane change, the system may switch to constant speed driving mode and accelerate. During this acceleration, a downshift occurs in the vehicle while it is accelerating, causing a delay in the vehicle's acceleration. As a result, the driver cannot obtain a smooth acceleration feeling. Specifically, as shown in Figure 2, when the preceding vehicle leaves its lane at time t1 and the preceding vehicle departure flag changes from OFF to ON, the requested acceleration Ar and the actual acceleration Aa of the vehicle, transmitted from the ACC controller to the drive source control unit, begin to increase starting at time t2. At this time, the virtual accelerator opening transmitted from the drive source control unit to the gear shift control unit also increases, and at time t3, if the virtual accelerator opening exceeds the downshift line DSL, which indicates the threshold of the virtual accelerator opening, the automatic transmission gear is downshifted from 6th gear to 5th gear. When a downshift occurs, the difference between the requested acceleration Ar and the actual acceleration Aa becomes larger. In other words, acceleration is delayed, and the increase in vehicle speed stagnates. As a result, the driver cannot experience a smooth acceleration feeling.

[0044] Therefore, the driving control unit 35, when the actual acceleration of the vehicle when a downshift is performed during acceleration at a predetermined vehicle speed in manual driving where follow driving control and constant speed driving control are not performed is defined as the downshift acceleration during manual driving, causes the transmission control unit 13 to control the automatic transmission 11 to perform a downshift in a predetermined situation where the required acceleration is smaller than the downshift acceleration during manual driving at the predetermined vehicle speed. By doing so, even if the required acceleration is small, if the required acceleration is increased later due to the circumstances, the occurrence of acceleration delay is prevented. Hereinafter, the control by which the driving control unit 35 causes the transmission control unit 13 to control the automatic transmission 11 to perform a downshift in a predetermined situation in preparation for acceleration may be referred to as downshift acceleration control.

[0045] Furthermore, the downshift acceleration during manual operation roughly matches the value of the required acceleration Ar at time t2 in Figure 2, for example, when the automatic transmission 11 downshifts from 6th gear to 5th gear. In other words, in Figure 2, the driving control unit 35 causes the gear shift control unit 13 to control the automatic transmission 11 to perform a downshift before time t3. Also, a predetermined situation in which the required acceleration is smaller than the downshift acceleration during manual operation at a predetermined vehicle speed is when the required acceleration is 0 meters per second squared (m / s²). 2 This includes the case where ) In this case, under predetermined conditions, the driving control unit 35 causes the shift control unit 13 to control the automatic transmission 11 to perform a downshift, even if the virtual accelerator opening is equivalent to the accelerator opening at which a downshift would not be performed in manual driving where the vehicle is not accelerating and neither follow-driving control nor constant-speed driving control is being performed.

[0046] The following describes in detail the conditions under which the driving control unit 35 causes the gear shift control unit 13 to control the automatic transmission 11 to perform a downshift, and the conditions under which the downshift acceleration control is performed.

[0047] The predetermined situation in which the required acceleration is smaller than the downshift acceleration during manual driving at a predetermined vehicle speed may include a first situation in which it is unpredictable whether the actual acceleration will increase after the required acceleration is small, excluding cases where the required acceleration remains small and cases where the actual acceleration changes from small to large. By doing so, if the required acceleration remains small, unnecessary downshifts will not be performed, thereby suppressing the deterioration of fuel efficiency (electricity consumption) due to downshifts that do not involve the vehicle's acceleration. Furthermore, in cases where it is known that the actual acceleration will change from small to large, such as the turn signal-linked acceleration control in ACC, it is predictable that the required acceleration will not remain small and that a downshift will be performed. In such cases, by not performing a downshift in advance, more appropriate ACC acceleration control can be achieved. Therefore, by limiting the predetermined situations in which downshifts are performed, it is possible to optimize the acceleration feeling.

[0048] The first situation is determined, for example, as follows: The driving control unit 35 has in advance a set of cases in which it can predict whether the actual acceleration will increase after the requested acceleration is small. The driving control unit 35 then determines that the current situation is the first situation if it does not match any of the cases it has in its set of cases. Furthermore, the turn signal-linked acceleration control in ACC is a function that provides an acceleration feeling similar to the preliminary acceleration performed by the driver pressing the accelerator pedal, by transmitting the requested acceleration from the ACC controller to the drive source control unit, starting with the operation of the turn signal in the vehicle when overtaking a preceding vehicle that is being followed.

[0049] Furthermore, the driving control unit 35 may, in the first situation where it is unpredictable whether the actual acceleration will increase after the required acceleration is low, except when the required acceleration remains low or when the actual acceleration increases, have the gear shift control unit 13 control the automatic transmission 11 to perform a downshift immediately after the vehicle starts accelerating. Immediately after the vehicle starts accelerating, the vehicle is hardly accelerating at all. Therefore, by performing a downshift immediately after the vehicle starts accelerating, the driving control unit 35 suppresses the lag in acceleration becoming apparent as the vehicle accelerates. In other words, the driving control unit 35 prevents the deterioration of acceleration feeling that occurs when a downshift is performed when the vehicle is accelerating.

[0050] Furthermore, the driving control unit 35 may, in the first situation where it is unpredictable whether the actual acceleration will increase after the required acceleration is low, except when the required acceleration remains low or when the actual acceleration increases, have the transmission control unit 13 control the automatic transmission 11 to perform a downshift during constant-speed driving before the vehicle accelerates. By doing so, the driving control unit 35 reduces shift shock and acceleration delay compared to when a downshift is performed during acceleration, thereby improving drivability.

[0051] The predetermined situation in which the required acceleration is smaller than the downshift acceleration during manual driving at a predetermined vehicle speed may include a second situation in which the preceding vehicle leaves the lane in which the vehicle is traveling. In this way, when the preceding vehicle detection unit 33 detects that the preceding vehicle has left the lane, the driving control unit 35 reduces the required acceleration considering the possibility that the preceding vehicle may return. Then, since the driving control unit 35 does not know whether a large actual acceleration is needed afterward, it performs a downshift to prevent acceleration delay or deterioration of the feeling due to gear changes when a large actual acceleration is actually needed.

[0052] Furthermore, in the second situation where the preceding vehicle deviates from the lane in which the vehicle is traveling, the transmission control unit 13 preferably sets the virtual accelerator opening transmitted from the drive source control unit 7 to be equal to or greater than a predetermined threshold at which a downshift is performed. The predetermined threshold at which a downshift is performed may hereafter be referred to as the downshift line.

[0053] Specifically, when a preceding vehicle leaves the lane in which the vehicle is traveling, the driving control unit 35 transmits a preceding vehicle departure signal to the transmission control unit 13 during the period when the preceding vehicle departure flag is ON. When the transmission control unit 13 receives the preceding vehicle departure signal transmitted from the driving control unit 35, it determines that the second situation is in place and sets the virtual accelerator opening transmitted from the drive source control unit 7 to be equal to or greater than a predetermined threshold at which a downshift is performed. When the virtual accelerator opening is equal to or greater than the predetermined threshold, the transmission control unit 13 controls the automatic transmission 11 to perform a downshift. In this way, the driving control unit 35 transmits a preceding vehicle departure signal to the transmission control unit 13 to cause the automatic transmission 11 to control a downshift, separately from transmitting an acceleration request signal to the drive source control unit 7. Therefore, the driving control unit 35 achieves a downshift without transmitting an acceleration request signal to the drive source control unit 7 that requests a large acceleration. In other words, the driving control unit 35 can reduce the likelihood of acceleration fluctuations in the vehicle until a downshift occurs. Furthermore, without changing the downshift line, which is the threshold for performing a downshift, the ACC controller 18 can be modified to transmit a preceding vehicle departure signal from the driving control unit 35 to the gear shift control unit 13, thereby enabling downshift acceleration control by the vehicle control device 1. As a result, development man-hours are significantly reduced, and substantial cost reductions are expected.

[0054] In this embodiment, in the second situation where the preceding vehicle deviates from the lane in which the vehicle is traveling, the virtual accelerator opening is set to a predetermined threshold or higher. However, the embodiment is not limited to this, and a downshift may be performed by lowering the predetermined threshold, i.e., the downshift line, without changing the virtual accelerator opening.

[0055] Figure 3 is a timing chart showing the time-series behavior of a vehicle equipped with a vehicle control device according to an embodiment of the present invention during gear shifting.

[0056] Now, referring to Figure 3, we will explain the downshift in the second scenario, where the preceding vehicle leaves the lane in which your vehicle is traveling. Note that the second scenario is the same as the scenario in Figure 2.

[0057] As shown in Figure 3, at time t1', when the preceding vehicle leaves its lane and the preceding vehicle departure flag changes from OFF to ON, the requested acceleration Ar and the actual acceleration Aa of the vehicle, transmitted from the ACC controller 18 to the drive source control unit 7, are still small. At this time, the driving control unit 35 transmits a preceding vehicle departure signal to the gear shift control unit 13, indicating that the preceding vehicle departure flag is ON. When the gear shift control unit 13 receives the preceding vehicle departure signal from the driving control unit 35, it adds an offset value VAOos to the virtual accelerator opening (virtual accelerator opening information) transmitted from the drive source control unit 7 to the gear shift control unit 13, and sets the virtual accelerator opening after adding the offset value VAOos to exceed the downshift line DSL. This causes the gear of the automatic transmission 11 to downshift from 6th gear to 5th gear. In other words, the vehicle control device 1 according to this embodiment performs a downshift before the requested acceleration Ar and actual acceleration Aa increase. By doing so, the downshift is already complete by time t2', when the required acceleration Ar and actual acceleration Aa begin to increase. As a result, the difference between the required acceleration Ar and actual acceleration Aa does not become excessively large from time t2' to time t3', and the vehicle speed increases linearly, reaching the target speed Vo at time t3'. Therefore, the driver of the vehicle can experience a smooth acceleration feeling.

[0058] Furthermore, the vehicle's speed is in the high-speed range, and it is preferable that the automatic transmission 11 is an automated manual transmission (AMT).

[0059] Specifically, the high-speed range for vehicle speeds is, for example, when the vehicle speed is 80 kilometers per hour (km) or higher. When the vehicle speed is not in the high-speed range, acceleration is guaranteed to some extent even without downshifting. Therefore, fuel efficiency (electricity efficiency) is improved by not performing downshifts when the vehicle speed is not in the high-speed range. Furthermore, an AMT includes, for example, a clutch that connects or disconnects power transmission from the drive source, multiple gear stages with different gear ratios, an actuator that controls the clutch and multiple gear stages hydraulically, and a hydraulic circuit that serves as the hydraulic power source for the actuator. The AMT is connected to the drive source via a clutch and performs gear changes by automatically controlling the clutch and gear stages. When driving with ACC in a vehicle equipped with an AMT, for example, when the preceding vehicle moves away due to a lane change and the vehicle accelerates, a downshift is performed to encourage acceleration during acceleration. At this time, the acceleration feeling is impaired due to the loss of torque characteristic of AMTs, resulting in a feeling of stalling. Therefore, the driving control unit 35 can significantly improve the acceleration feeling by having the gear shift control unit 13 control the automatic transmission 11 (ATM) to perform a downshift in predetermined conditions where the required acceleration is smaller than the downshift acceleration during manual driving at a predetermined vehicle speed.

[0060] Furthermore, it is preferable that the driving control unit 35, based on the determination result of the second turn signal operation determination unit 37, causes the gear shift control unit 13 to control the automatic transmission 11 to return to the gear position before the downshift when a preceding vehicle traveling in an adjacent lane adjacent to the current lane signals in the direction of the current lane. Let's consider the situation after a downshift is performed in the second situation in which the preceding vehicle leaves the current lane in which the current vehicle is traveling. After the preceding vehicle traveling in an adjacent lane adjacent to the current lane signals in the direction of the current lane, it is expected that the preceding vehicle will move into the current lane and become the vehicle to follow. In this case, the current vehicle usually does not need to accelerate. Therefore, the driving control unit 35 quickly determines that acceleration is not necessary and returns to the gear position before the downshift is performed, thereby improving the effect of fuel efficiency (electricity efficiency) and preventing the current vehicle from unnecessarily accelerating too much. Furthermore, the preceding vehicle traveling in the adjacent lane to the current lane may be the preceding vehicle that deviated in the second situation, or it may be any preceding vehicle other than the preceding vehicle that deviated in the second situation.

[0061] The predetermined situation in which the required acceleration is smaller than the downshift acceleration during manual driving at a predetermined vehicle speed preferably includes a third situation in which the preceding vehicle illuminates its turn signal in the direction of leaving the lane in which the own vehicle is traveling. Specifically, when the preceding vehicle illuminates its turn signal in the direction of leaving the own lane, it is expected that the preceding vehicle will subsequently leave the lane. Therefore, by performing a downshift at a timing when the departure of the preceding vehicle can be predicted, preparations for the preceding vehicle to leave the lane and for the own vehicle to accelerate can be made earlier. Moreover, by synchronizing the timing of the downshift with the illumination of the preceding vehicle's turn signal, which is visible to the driver, it is possible to suppress the driver's feeling of discomfort associated with the downshift and improve the acceleration feeling.

[0062] Furthermore, it is preferable for the driving control unit 35 to determine that a predetermined situation exists where the acceleration requested from the drive source control unit 7 is smaller than the downshift acceleration during manual driving at a predetermined vehicle speed, when the speed at which the preceding vehicle crosses the lane markings of the vehicle is above a certain speed. Then, when the vehicle has traveled to the position of the rear end of the preceding vehicle at the time the predetermined situation was determined, it is preferable for the driving control unit 35 to determine that the preceding vehicle will not return to the vehicle's lane, that is, that the preceding vehicle has left the vehicle's lane, and to perform a large acceleration for the vehicle. When a preceding vehicle crosses the lane markings of the vehicle's lane at a certain speed or higher, there is a high probability that the preceding vehicle will leave the vehicle's lane and travel in an adjacent lane. In other words, there is a low probability that a preceding vehicle that is about to leave the vehicle's lane will subsequently return to the vehicle's lane. Therefore, when the speed at which the preceding vehicle crosses the lane markings of the vehicle's lane is above a certain speed, the driving control unit 35 makes an early determination that the preceding vehicle that is about to leave the vehicle's lane will not return to the vehicle's lane. As a result, the driving control unit 35 speeds up the transition of the vehicle to a high-speed acceleration, enabling comfortable acceleration for the driver.

[0063] Furthermore, when the departure speed determination flag is ON, the driving control unit 35 determines that the speed at which the preceding vehicle crosses the lane markings of the own vehicle is above a certain speed. Also, when the arrival flag is ON, the driving control unit 35 determines that the own vehicle has traveled to the position of the rear end of the preceding vehicle at the time the predetermined situation was determined to be met.

[0064] Figure 4 shows an example of determining when a preceding vehicle will leave the vehicle during downshift acceleration control by a vehicle control device according to an embodiment of the present invention.

[0065] Referring to Figure 4, we will now further explain the determination of whether a preceding vehicle will leave the lane when its speed exceeds a certain speed at which it crosses the left or right lane marking. In Figure 4, road R is a three-lane road in each direction, including lanes DL1 to DL3.

[0066] As shown in Figure 4, the driving control unit 35 determines that a predetermined condition exists where the requested acceleration to the drive source control unit 7 is smaller than the downshift acceleration during manual driving at a predetermined vehicle speed, when the speed LV at which the preceding vehicle VB crosses the lane marking (left lane marking) LDL or the lane marking (right lane marking) RDL of the lane DL2 in which the vehicle VA is traveling is above a certain speed. Then, when the vehicle VA has traveled to the position P of the rear end of the preceding vehicle VB at the time the driving control unit 35 determined that the preceding vehicle VB has not returned to the vehicle lane DL2, that is, has left the lane.

[0067] Figure 5 is a flowchart showing an example of the processing procedure for downshift acceleration control by a vehicle control device according to an embodiment of the present invention.

[0068] Figure 6 is a flowchart showing an example of an alternative process for the process enclosed by the dashed line A in Figure 5.

[0069] Figure 7 is a flowchart showing other examples of alternative processes to the process enclosed by the dashed line A in Figure 5.

[0070] Now, referring to Figures 5 to 7, the operation of the vehicle control device 1 according to this embodiment (downshift acceleration control) described above will be explained.

[0071] As shown in Figure 5, first, in step S1, the ACC becomes active. In other words, the vehicle control device 1 is in a state where it can perform follow-me driving control or constant speed driving control when the ACC switch 15 is turned ON by the driver.

[0072] In step S2, following step S1, the vehicle control device 1 determines whether or not it has detected a preceding vehicle. If a preceding vehicle is detected (YES in step S2), the process proceeds to step S3. If a preceding vehicle is not detected (NO in step S2), the process in step S2 is repeated until a preceding vehicle is detected.

[0073] In step S3, following the YES in step S2, the vehicle control device 1 determines whether it is unclear whether the actual acceleration will increase after the required acceleration is low. However, the vehicle control device 1 makes this determination except when the required acceleration remains low and when the actual acceleration changes from a low acceleration to a high acceleration. If it is unclear whether the actual acceleration will increase after the required acceleration is low (YES in step S3), the process proceeds to step S4. If it is not unclear whether the actual acceleration will increase after the required acceleration is low (NO in step S3), the process returns to step S2 and steps S2 and S3 are repeated.

[0074] In step S4, following the YES response in step S3, the vehicle control device 1 performs a downshift. In other words, the vehicle control device 1 performs a downshift in advance, so that when acceleration is actually needed, it prevents acceleration delay and enables a superior acceleration feeling.

[0075] In step S5, following step S4, the vehicle control device 1 determines whether the acceleration condition for its own vehicle has ended. If the acceleration condition has ended (YES in step S5), the current control is terminated. If the acceleration condition has not ended (NO in step S5), the process in step S5 is repeated until the acceleration condition is ended.

[0076] Here, the processes from steps S3 to S5 enclosed by the dashed line A in Figure 5 are the alternative processes shown in Figure 6 and can be replaced by the processes from steps S13 to S15 enclosed by the dashed line A1. The processes from steps S13 to S15, which are performed in place of the processes from steps S3 to S5, will be explained below with reference to Figure 6.

[0077] As shown in Figure 6, in step S13, following step S2's YES, the vehicle control device 1 determines whether the preceding vehicle traveling ahead of its lane has deviated from the lane. If the preceding vehicle has deviated (step S13's YES), the process proceeds to step S14. On the other hand, if the preceding vehicle has not deviated (step S13's NO), that is, if follow-the-preceding control is still in operation, the process returns to step S2 and steps S2 and S13 are repeated.

[0078] In step S14, following the YES response in step S13, the vehicle control device 1 performs a downshift. If the preceding vehicle that has pulled away does not return, the vehicle will switch to constant speed driving control and accelerate. However, by performing a downshift in advance, acceleration delay can be prevented, making it possible to achieve a superior acceleration feeling.

[0079] In step S15, following step S14, the vehicle control device 1 determines whether acceleration has ended or whether a preceding vehicle has appeared in front of its lane within a predetermined interval. If acceleration has ended or a preceding vehicle has appeared within the predetermined interval (YES in step S15), the current control is terminated. If acceleration has not ended or a preceding vehicle has not appeared within the predetermined interval (NO in step S15), the process in step S15 is repeated until acceleration has ended or a preceding vehicle has appeared within the predetermined interval.

[0080] Here, the processes from step S3 to step S5 enclosed by the dashed line A in Figure 5 are alternative processes shown in Figure 7 and can be further replaced by the processes from step S23 to step S25 enclosed by the dashed line A2. The processes from step S23 to step S25, which are performed in place of the processes from step S3 to step S5, will be explained below with reference to Figure 7.

[0081] As shown in Figure 7, in step S23 following YES in step S2, the vehicle control device 1 determines whether or not the preceding vehicle is expected to deviate from its lane. If the preceding vehicle is expected to deviate (YES in step S23), the process proceeds to step S24. If the preceding vehicle is not expected to deviate (NO in step S23), the process returns to step S2 and steps S2 and S23 are repeated. The situation in which the preceding vehicle is expected to deviate is, for example, when the preceding vehicle turns on its turn signal in the direction of deviating from the vehicle's lane, or when the speed at which the preceding vehicle crosses the lane markings exceeds a certain speed.

[0082] In step S24, following the YES response in step S23, the vehicle control device 1 performs a downshift. If the preceding vehicle that has pulled away does not return, the vehicle will switch to constant speed driving control and accelerate. By performing a downshift early, acceleration delay can be further prevented during the vehicle's acceleration, resulting in a better acceleration feeling. Furthermore, even if the preceding vehicle that pulled away unexpectedly returns and acceleration is no longer necessary, the vehicle control device 1 can perform a downshift early, for example, to return to the gear position before the downshift with ample margin.

[0083] In step S25, following step S24, the vehicle control device 1 determines whether acceleration has ended, whether a preceding vehicle has appeared within a predetermined interval, or whether it has detected the preceding vehicle's turn signal being activated towards the vehicle's lane. If acceleration has ended, a preceding vehicle has appeared within a predetermined interval, or the preceding vehicle's turn signal being activated towards the vehicle's lane is detected (YES in step S25), the current control is terminated. If acceleration has not ended, a preceding vehicle has not appeared within a predetermined interval, or the preceding vehicle's turn signal being activated towards the vehicle's lane is not detected (NO in step S25), the process in step S25 is repeated until acceleration has ended, a preceding vehicle has appeared within a predetermined interval, or the preceding vehicle's turn signal being activated towards the vehicle's lane is detected.

[0084] As described above, the vehicle control device 1 according to this embodiment includes a driving control unit 35 that causes the transmission control unit 13 to control the automatic transmission 11 to perform a downshift when the actual acceleration of the vehicle is used as the downshift acceleration during manual driving, and the required acceleration is smaller than the downshift acceleration during manual driving at the predetermined vehicle speed in a predetermined situation.

[0085] Furthermore, in the vehicle control device 1 according to this embodiment, the predetermined situation in which the required acceleration is smaller than the downshift acceleration during manual driving at a predetermined vehicle speed includes a first situation in which it is unpredictable whether the actual acceleration will increase after the required acceleration is small, excluding cases where the required acceleration remains small and cases where the actual acceleration changes from a small acceleration to a large acceleration. When the required acceleration remains small and the situation does not fall under the first situation, the vehicle control device 1 does not perform an unnecessary downshift. Therefore, the vehicle control device 1 can suppress the deterioration of fuel efficiency (electricity consumption) due to downshifts that do not involve the acceleration of the vehicle. Also, in cases where it is known that the actual acceleration will change from a small acceleration to a large acceleration, such as turn signal-linked acceleration control in ACC, it is predictable that the required acceleration will not remain small and that a downshift will be performed. In such cases, which do not fall under the first situation, the vehicle control device 1 can achieve more appropriate ACC acceleration control by not performing a downshift in advance. In other words, the vehicle control device 1 does not simply prepare for acceleration by moving up the timing of the downshift, but takes into account the individual situations in which the vehicle is being accelerated. Therefore, the vehicle control device 1 can optimize the acceleration feeling by limiting the predetermined conditions under which downshifting is performed.

[0086] Furthermore, the vehicle control device 1 according to this embodiment includes a driving control unit 35 that, in a first situation where it is unpredictable whether the actual acceleration will increase after the required acceleration is low (excluding cases where the required acceleration remains low and cases where the actual acceleration increases), causes the gear shift control unit 13 to control the automatic transmission 11 to perform a downshift immediately after the vehicle starts accelerating. Immediately after the vehicle starts accelerating, the vehicle is hardly accelerating at all. Therefore, by performing a downshift immediately after the vehicle starts accelerating in the first situation, the vehicle control device 1 can suppress the acceleration delay from becoming apparent as the vehicle accelerates. In other words, the vehicle control device 1 can prevent the deterioration of the acceleration feeling that occurs when a downshift is performed when the vehicle is accelerating.

[0087] Furthermore, the vehicle control device 1 according to this embodiment includes a driving control unit 35 that causes the transmission control unit 13 to control the automatic transmission 11 to perform a downshift during constant-speed driving before acceleration, in a first situation where it is not possible to predict whether the actual acceleration will increase after the required acceleration is low, except when the required acceleration remains low or when the actual acceleration increases. As a result, the vehicle control device 1 can reduce shift shock and acceleration delay compared to when a downshift is performed during acceleration, thereby improving drivability.

[0088] Furthermore, in the vehicle control device 1 according to this embodiment, the predetermined situation in which the required acceleration is smaller than the downshift acceleration during manual driving at a predetermined vehicle speed includes a second situation in which the preceding vehicle leaves the lane in which the own vehicle is traveling. If the preceding vehicle that has left the lane returns to the lane, there is no need to accelerate the own vehicle in order to follow the returning preceding vehicle. On the other hand, if the preceding vehicle that has left the lane does not return to the lane, it is necessary to accelerate the own vehicle. In other words, in the second situation, it is unclear whether or not a large actual acceleration will be required afterward. Therefore, by performing a downshift in the second situation, the vehicle control device 1 can prevent acceleration delays and deterioration of the feeling due to gear changes when a large actual acceleration is actually required.

[0089] Furthermore, the vehicle control device 1 according to this embodiment includes a gear shift control unit 13 that, in a second situation where a preceding vehicle leaves the lane in which the vehicle is traveling, sets the virtual accelerator opening transmitted from the drive source control unit 7 to a predetermined threshold value or higher for downshifting to be performed. As a result, the vehicle control device 1 can perform downshifting without the driving control unit 35 sending an acceleration request signal to the drive source control unit 7 requesting a large acceleration. In other words, the vehicle control device 1 can reduce the likelihood of acceleration fluctuations in the vehicle until downshifting occurs. Moreover, by simply redesigning the ACC controller 18 so that the driving control unit 35 transmits the preceding vehicle departure signal to the gear shift control unit 13, downshift acceleration control by the vehicle control device 1 becomes possible. As a result, development man-hours for the vehicle control device 1 can be significantly reduced, leading to substantial cost savings.

[0090] Furthermore, in the vehicle control device 1 according to this embodiment, the vehicle speed is in the high-speed range, and the automatic transmission 11 is an AMT. Therefore, the vehicle control device 1 can improve fuel efficiency (electricity consumption) by not performing a downshift when the vehicle speed is in the low to medium range where a certain degree of acceleration can be guaranteed without performing a downshift. In addition, in predetermined situations where the required acceleration is smaller than the downshift acceleration during manual driving at a predetermined vehicle speed, the vehicle control device 1 can reduce the effects of torque loss and significantly improve the acceleration feeling by having the gear shift control unit 13 control the automatic transmission 11, which is an AMT, to perform a downshift.

[0091] Furthermore, the vehicle control device 1 according to this embodiment includes a driving control unit 35 that, based on the determination result of the second turn signal operation determination unit 37, causes the transmission control unit 13 to control the automatic transmission 11 to return to the gear position before downshifting when a preceding vehicle traveling in an adjacent lane adjacent to the vehicle's lane signals in the direction of the vehicle's lane. As a result, the vehicle control device 1 can quickly determine that acceleration is not necessary and return to the gear position before downshifting, thereby improving fuel efficiency (electricity consumption) and suppressing unintentional large acceleration in the vehicle.

[0092] Furthermore, in the vehicle control device 1 according to this embodiment, a predetermined situation in which the required acceleration is smaller than the downshift acceleration during manual driving at a predetermined vehicle speed includes a third situation in which the preceding vehicle illuminates its turn signal in the direction of leaving the lane in which the own vehicle is traveling. Therefore, by performing a downshift at a timing in which the departure of the preceding vehicle can be predicted, the vehicle control device 1 can prepare for the preceding vehicle to leave the lane and for the own vehicle to accelerate at an early stage. Moreover, by synchronizing the timing of the downshift with the illumination of the turn signal of the preceding vehicle, which is visible to the driver, the vehicle control device 1 can suppress the driver from feeling any discomfort associated with the downshift and improve the driving feel.

[0093] Furthermore, the vehicle control device 1 according to this embodiment includes a driving control unit 35 that determines a predetermined situation where the acceleration requested to the drive source control unit 7 is smaller than the downshift acceleration during manual driving at a predetermined vehicle speed, when the speed at which the preceding vehicle crosses the lane markings of the vehicle is above a certain speed. In addition, the driving control unit 35 determines that when the vehicle has traveled to the position of the rear end of the preceding vehicle at the time the predetermined situation is determined, the preceding vehicle will not return to the vehicle's lane, that is, the preceding vehicle has left the vehicle's lane, and performs a large acceleration for the vehicle.Therefore, when the speed at which the preceding vehicle crosses the lane markings of the vehicle is above a certain speed, the vehicle control device 1 can determine earlier that the preceding vehicle that is about to leave the lane will not return to the vehicle's lane, and can accelerate the transition to a large acceleration for the vehicle.In other words, the vehicle control device 1 can achieve a comfortable acceleration for the driver.

[0094] Therefore, according to the vehicle control device 1 of this embodiment, it is possible to prevent acceleration delays and achieve an excellent acceleration feeling when accelerating the vehicle in ACC mode.

[0095] While several embodiments of the present invention have been described, these embodiments are presented as examples only and are not intended to limit the scope of the invention. These novel embodiments can be carried out in a variety of other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their variations are included in the scope and spirit of the invention, as well as in the claims of the invention and its equivalents. [Explanation of symbols]

[0096] 1...Vehicle control device, 3...Surroundings detection unit, 5...Wheel speed sensor, 7...Drive source control unit, 9...Brake control unit, 11...Automatic transmission, 13...Shift control unit, 15...ACC switch, 16...ACC setting switch, 17...Human-machine interface device (HMI device), 18...ACC controller, 19...In-vehicle network, 21...Camera sensor, 22...Radar sensor, 31...ACC determination unit, 32...Vehicle speed acquisition unit, 33...Preceding vehicle detection unit, 35...Driving control unit, 36...First turn signal operation determination unit, 37...Second turn signal operation determination unit.

Claims

1. A surrounding detection unit that detects targets in the vicinity of the vehicle, A drive source control unit that controls the drive source that generates the propulsion force of the vehicle, The automatic transmission that performs the gear changes of the vehicle, A gear shift control unit that controls the aforementioned automatic transmission, The vehicle speed acquisition unit acquires the vehicle speed of the vehicle, A preceding vehicle detection unit detects a preceding vehicle traveling in front of the vehicle's own lane based on the detection results of the surrounding area detection unit, The vehicle includes a driving control unit that, when the preceding vehicle detection unit detects the preceding vehicle, performs follow-up driving control to make the vehicle follow the preceding vehicle for a set interval time, and when the preceding vehicle detection unit does not detect the preceding vehicle, performs constant-speed driving control to make the vehicle drive at a set speed, and changes the requested acceleration to the drive source control unit in both the follow-up driving control and the constant-speed driving control depending on the situation, The aforementioned driving control unit is a vehicle control device that, when the actual acceleration of the vehicle during acceleration at a predetermined vehicle speed in manual driving where the follow driving control and the constant speed driving control are not performed is defined as the manual driving downshift acceleration, causes the gear shift control unit to control the automatic transmission to perform a downshift in a predetermined situation where the required acceleration is smaller than the manual driving downshift acceleration at the predetermined vehicle speed.

2. The vehicle control device according to claim 1, wherein the predetermined conditions include a first condition in which it is unpredictable whether the actual acceleration will increase after the required acceleration is low, excluding cases where the required acceleration remains low and cases where the actual acceleration changes from a low acceleration to a high acceleration.

3. The vehicle control device according to claim 2, wherein the driving control unit causes the transmission control unit to control the automatic transmission to perform a downshift immediately after the vehicle starts accelerating in the first situation.

4. The vehicle control device according to claim 2, wherein the driving control unit causes the transmission control unit to control the automatic transmission and perform a downshift during constant-speed driving before acceleration of the vehicle in the first situation.

5. The vehicle control device according to claim 1, wherein the predetermined condition includes a second condition in which the preceding vehicle departs from the vehicle's own lane.

6. The vehicle control device according to claim 5, wherein the gear shift control unit, in the second situation, sets the virtual accelerator opening transmitted from the drive source control unit to be greater than or equal to a predetermined threshold at which a downshift is performed.

7. The vehicle speed of the aforementioned vehicle is in the high-speed range. The vehicle control device according to claim 1, wherein the type of automatic transmission is an automated manual transmission.

8. The system includes a second turn signal operation determination unit that determines whether or not a preceding vehicle traveling in an adjacent lane adjacent to the current lane has activated its turn signal on the current lane. The vehicle control device according to claim 5, wherein the driving control unit, based on the determination result of the second turn signal operation determination unit, causes the preceding vehicle traveling in the adjacent lane adjacent to the current lane to illuminate the turn signal on the current lane side, to cause the gear shift control unit to control the automatic transmission to return to the gear position before downshifting.

9. The vehicle control device according to claim 1, wherein the predetermined conditions include a third condition in which the preceding vehicle illuminates its turn signal in the direction of leaving its own lane.

10. The aforementioned driving control unit, When the speed at which the preceding vehicle crosses the lane markings of its own lane is above a certain speed, it is determined that the predetermined condition exists. The vehicle control device according to claim 1, which, when it is determined that the predetermined conditions are met, has traveled to the position of the rear end of the preceding vehicle at that point, determines that the preceding vehicle will not return to its own lane and performs a large acceleration relative to the vehicle.

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