Deceleration assist control device for vehicle

Abstract

The present application relates to a deceleration assist control device for a vehicle, comprising a control means for performing deceleration assist control in an accelerator opening mode in which a vehicle is decelerated in accordance with an accelerator opening by controlling a deceleration device when a deceleration target is detected in a condition in which the accelerator opening exceeds a reference value, the control means calculates a target deceleration at which the vehicle speed when the vehicle arrives at the position of the deceleration target becomes a target vehicle speed determined by the type of the deceleration target, sets the timing at which the mode is changed in accordance with the type of the deceleration target, and when the timing is determined to be the timing at which the mode is changed. A mode change from an accelerator opening mode to a non-accelerator opening mode is performed.

Description

Technical Field

[0001] The present invention relates to a deceleration auxiliary control device for vehicles such as automobiles. Background Art

[0002] As one of the driving assistance controls for vehicles such as automobiles, there is known a deceleration assistance control that automatically decelerates the vehicle when a deceleration target, such as an intersection without traffic lights, is detected in front of the vehicle.

[0003] For example, Japanese Patent Application Laid-Open No. 2021-116000 described below describes a deceleration assist device configured to assist deceleration when a deceleration target is detected and a deceleration assist start condition is satisfied and the accelerator is not on, that is, when the accelerator pedal is not depressed. Summary of the invention

[0004] As a deceleration assist device, there is a known case where, even if the accelerator is turned on, that is, the accelerator pedal is depressed, when the accelerator pedal is restored and the accelerator pedal opening starts to decrease, deceleration assistance is performed according to the accelerator opening. According to this deceleration assist device, deceleration control can be started in advance, thereby improving the effect of deceleration assistance.

[0005] However, when the accelerator is turned on and deceleration assistance is performed according to the accelerator opening, the driver must control the vehicle speed by controlling the amount of depression of the accelerator pedal. Therefore, it is not easy to control the vehicle speed to a desired speed depending on the type of deceleration object and the driving condition of the vehicle.

[0006] For example, when the deceleration target is a deceleration target such as a red light that requires the vehicle to stop, the vehicle speed must be controlled so that the vehicle speed becomes 0 when the vehicle reaches the deceleration target. In addition, when the road is an uphill road, in addition to the deceleration based on the deceleration assistance, the deceleration caused by the inclination of the road also acts on the vehicle, causing the deceleration of the vehicle to become higher than the deceleration desired by the driver. In addition, when the driver performs a steering operation while reducing the accelerator opening, the driver must control the vehicle speed based on the accelerator opening while controlling the vehicle's travel direction based on the steering operation.

[0007] The present invention provides a deceleration assist control device which is improved to be able to improve the deceleration assist effect by starting deceleration control in advance and to be able to control the vehicle speed to a desired vehicle speed more easily than before regardless of the type of deceleration object.

[0008] According to the present invention, a deceleration assist control device (10) for a vehicle is provided, which comprises: an accelerator opening detection device (accelerator opening sensor 64) for detecting an accelerator opening (Acc), a deceleration object detection device (56) for detecting a deceleration object (such as a T-junction 80) in front of a vehicle (16), a deceleration device (30) for decelerating the vehicle, and a control unit (driving assistance ECU 50) for controlling the deceleration device, wherein the control unit is configured to: when the accelerator opening exceeds a reference value (Accc) (S40) and the deceleration object is detected (S10), the deceleration assist control (S80) is performed by controlling the deceleration device in an accelerator opening mode for decelerating the vehicle according to the accelerator opening. The control unit (driving assistance ECU 50) is configured to: calculate a target deceleration (Gbt) for making the vehicle speed (V) when the vehicle reaches the position of the deceleration object become a target vehicle speed (Vt) determined by the type of deceleration object, set the timing (tc) of the mode change according to the type of the deceleration object, and when it is determined that it is the timing of the mode change (S70), perform a mode change (S90) from the accelerator opening mode to the non-accelerator opening mode that decelerates the vehicle based on the target deceleration (S100).

[0009] According to the above configuration, a target deceleration is calculated to make the vehicle speed when the vehicle reaches the position of the deceleration object become the target vehicle speed determined by the type of the deceleration object, and the timing of the mode change is set according to the type of the deceleration object. In addition, when it is determined that it is the timing of the mode change, the deceleration auxiliary control is performed from the accelerator opening mode to the non-accelerator opening mode that decelerates the vehicle based on the target deceleration.

[0010] Therefore, the deceleration of the vehicle is first controlled according to the accelerator opening in the accelerator opening mode, and when it is determined that it is time to change the mode, it is automatically controlled according to the target deceleration in the non-accelerator opening mode. Therefore, after the mode is changed, the driver can control the vehicle speed to the desired speed without controlling the amount of accelerator pedal depression. Therefore, the effect of deceleration assistance can be improved by starting the deceleration control in advance, and the vehicle speed can be controlled to the desired speed more easily than before.

[0011] In addition, according to the above configuration, a target deceleration is calculated for making the vehicle speed a target speed determined by the type of deceleration object, and the timing of the mode change is set according to the type of deceleration object. Thus, the vehicle speed can be easily controlled to a desired speed regardless of the type of deceleration object, and the mode change can be performed at a timing corresponding to the type of deceleration object.

[0012] In one embodiment of the present invention, the control unit (driving assistance ECU 50) is configured to: when it is determined that the deceleration object is an object that requires the vehicle (16) to stop (S22), and when it is determined that a specified time has passed since the deceleration object was first detected, it is determined that it is the timing for the mode change (S70).

[0013] According to the above aspect, when it is determined that the deceleration target is an target for which the vehicle needs to be stopped, the mode can be changed from the accelerator opening mode to the non-accelerator opening mode when a predetermined time has elapsed since the deceleration target was first detected.

[0014] In another embodiment of the present invention, the control unit (driving assistance ECU 50) is configured to variably set the predetermined time (S22, S24, S30) according to at least one of the type of deceleration target and the running condition of the vehicle.

[0015] According to the above aspect, the timing of changing the mode from the accelerator opening mode to the non-accelerator opening mode can be variably set according to at least one of the type of the deceleration target and the travel condition of the vehicle.

[0016] In another embodiment of the present invention, the control unit (driving assistance ECU 50) is configured to, when determining that a steering operation is being performed (S30), advance the timing of the mode change compared to when determining that a steering operation is not being performed (S36).

[0017] According to the above aspect, when the steering operation is being performed, the timing of the mode change can be advanced compared to when the steering operation is not being performed, and the timing of decelerating the vehicle based on the target deceleration can be advanced. Therefore, compared to the case where the timing of the mode change is not advanced, the driver can concentrate on the steering operation without controlling the accelerator opening.

[0018] In another embodiment of the present invention, the control unit (driving assistance ECU 50) is configured to, when it is determined that there are multiple deceleration targets (S32), advance the timing of the mode change (S36) compared to when it is determined that there is only one deceleration target.

[0019] According to the above aspect, when there are multiple deceleration targets, the timing of mode change can be advanced compared to when there is only one deceleration target, and the timing of decelerating the vehicle based on the target deceleration can be advanced. Therefore, compared to the case where the timing of mode change is not advanced, the driver can be relieved from having to control the accelerator opening.

[0020] Other objects, other features and attendant advantages of the present invention can be easily understood from the following description of the embodiments of the present invention with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Features, advantages and technical and industrial significance of exemplary embodiments of the present invention are described with reference to the accompanying drawings, in which like reference numerals represent like parts, and in which: Figure 1 It is a schematic diagram showing the configuration of a deceleration assist device according to an embodiment. Figure 2 1 is a flowchart showing a deceleration assist control routine according to the embodiment. Figure 3 This is a flowchart showing a subroutine for determining the ratio Rec in the first embodiment. Figure 4 This is a flowchart showing a subroutine for determining the ratio Rec in the second embodiment. Figure 5A 1 is a diagram showing an example of changes in the vehicle speed V of the vehicle when a deceleration object is detected in front of the vehicle with the accelerator on. Figure 5B 1 is a diagram showing an example of changes in the vehicle speed V of the vehicle when a deceleration object is detected in front of the vehicle with the accelerator on. Figure 5C 1 is a diagram showing an example of changes in the vehicle speed V of the vehicle when a deceleration object is detected in front of the vehicle with the accelerator on. Figure 6 The diagram shows a situation where a vehicle is approaching a T-junction to be decelerated. DETAILED DESCRIPTION

[0022] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0023] Figure 1 The vehicle deceleration assist control device 10 involved in the illustrated embodiment is applicable to a vehicle 16 having wheels 14FL, 14FR, 14RL and 14RR. The vehicle 16 may be a vehicle capable of automatic driving. In the embodiment, the left and right front wheels 14FL and 14FR are steering wheels and driving wheels, and the left and right rear wheels 14RL and 14RR are non-steering wheels and driven wheels. The front wheels 14FL and 14FR are steered by an electric power steering device 20 via a rack bar 22 and tie rods 24L and 24R, and the electric power steering device 20 is driven in response to the driver's operation of the steering wheel 18. In addition, in the following description, the electronic control device is referred to as an electronic control unit (ECU).

[0024] The deceleration assist control device 10 includes a deceleration device 30 for decelerating the vehicle 16, and a driving assist ECU 50 as a control unit for controlling the deceleration device. The deceleration device 30 includes a brake device 32 for applying a friction braking force to the wheels 14FL to 14RR, and a brake ECU 34 for controlling the brake device. The brake device 32 includes a hydraulic circuit 36, friction braking force generating devices 38FR, 38FL, 38RR, and 38RL provided on the wheels 14FL to 14RR, and a master cylinder 42 for pumping brake oil in response to the driver's stepping operation on the brake pedal 40. Although Figure 1 Although not shown in detail, the hydraulic circuit 36 ​​includes a reservoir, an oil pump, various valve devices, etc., and functions as a brake actuator.

[0025] The brake device 32 applies a braking force proportional to the pressure in the corresponding wheel cylinder of the friction braking force generating device 38FR to 38RL to the wheels 14FL to 14RR. The pressure in the wheel cylinder is usually controlled according to the pressure in the master cylinder 42 (master cylinder pressure Pm), and the master cylinder 42 is driven according to the driver's stepping on the brake pedal 40. That is, the master cylinder pressure Pm is detected by the pressure sensor 44, and the pressure in each wheel cylinder is controlled by the brake ECU 34 based on the master cylinder pressure Pm. In addition, the oil pump and various valve devices are controlled by the brake ECU 34 as needed, thereby controlling the pressure in each wheel cylinder regardless of the amount of the driver's stepping on the brake pedal 40, and automatic braking is performed.

[0026] The vehicle 16 has a drive device 60 such as an engine that applies a driving force to the left and right front wheels 14FL and 14FR as driving wheels. The amount of depression of the accelerator pedal 62 by the driver is detected by the accelerator opening sensor 64 as the accelerator opening Acc. The output of the drive device 60 is usually controlled by the drive ECU 66 based on the accelerator opening Acc, and is controlled independently of the accelerator opening Acc as needed. In addition, the drive device 60 can be any device that can apply a driving force to the driving wheels, for example, it can be an electric motor, a hybrid system, etc. The driving wheels can be the left and right rear wheels 14RL and 14RR, or the four wheels 14FL to 14RR.

[0027] In addition, if Figure 1 As shown by the dotted line in FIG. 3 , the drive device 60 may also include a regeneration device 66, which generates a regenerative braking force by converting the rotational energy of the drive wheel into electrical energy. The regeneration device 66 is controlled by the drive ECU 66 according to the control command from the brake ECU 34. The regeneration device 66 functions as a part of the deceleration device 30 when generating the regenerative braking force.

[0028] Each ECU has a microcomputer as its main part, which includes a CPU, ROM, RAM, a readable and writable non-volatile memory (N / M), and an interface (I / F). The CPU implements various functions by executing instructions (programs, routines) stored in the ROM. In addition, these ECUs are connected to each other via a controller area network (CAN) so that they can exchange data (communicate). Therefore, the detection values ​​of sensors (including switches) connected to a specific ECU will also be sent to other ECUs. In addition, multiple ECUs can also be merged into one ECU.

[0029] The driving assistance ECU 50 is a central control device that performs driving assistance control such as deceleration assistance control, following distance control, lane departure prevention control, etc. In the embodiment, the driving assistance ECU 50 cooperates with other ECUs to perform deceleration assistance control based on automatic braking, which will be described in detail later.

[0030] The driving assistance ECU 50 is connected to a camera sensor 52 and a radar sensor 54. The camera sensor 52 and the radar sensor 54 may include a plurality of camera devices and a plurality of radar devices, respectively. The camera sensor 52 and the radar sensor 54 function as a deceleration object detection device 56 for detecting a deceleration object at least in front of the vehicle 16. In addition, a Light Detection And Ranging (LiDAR) may be used as a substitute for the radar sensor 14 or as a supplement to the radar sensor 14.

[0031] The deceleration object may be a red light, a road sign and road marking for temporary parking, an intersection without a signal light (a crossroad, a T-junction, or a branch intersection where the road the vehicle is traveling on is not a priority road), a stopped vehicle, a curved road, a preceding vehicle, etc. In this application, a red light, a road sign and road marking for temporary parking, and an intersection without a signal light are referred to as a parking target object as needed. A parking target object is an object that requires the vehicle to stop.

[0032] The driving assistance ECU 50 is also connected to a steering angle sensor 70, a vehicle speed sensor 72, and a deceleration assist switch 74. The steering angle sensor 70 detects the steering angle θ as the amount of operation of the steering wheel 18 by the driver. The vehicle speed sensor 72 detects the vehicle speed V as the running speed of the vehicle 16. The deceleration assist switch 74 is operated by the driver, and when the deceleration assist switch is turned on, the driving assistance ECU 50 performs deceleration assist control as described later. Figure 1 Although not shown, a display device that displays the status of driving assistance control such as deceleration assistance control may be connected to the driving assistance ECU 50 .

[0033] When the driving assistance ECU 50 detects a deceleration target under the condition that the accelerator opening Acc exceeds the reference value Accc (0 or a positive constant), it controls the deceleration device 30 to perform deceleration assistance control in an accelerator opening mode for decelerating the vehicle 16 according to the accelerator opening. Figure 2 In FIG. 1 , the accelerator opening mode is indicated as the ACC mode.

[0034] The driving assistance ECU 50 calculates a target deceleration rate Gbt for causing the vehicle speed of the vehicle 16 to reach the position of the deceleration object, which is a target vehicle speed Vt determined by the type of the deceleration object, and sets the timing of the mode change according to the type of the deceleration object. In addition, when the deceleration object is a leading vehicle, the position of the deceleration object is the position of the leading vehicle when the leading vehicle is first detected. Furthermore, when the driving assistance ECU 50 determines that it is the timing for the mode change, it changes the mode of the deceleration assist control from the accelerator opening mode to the non-accelerator opening mode that decelerates the vehicle based on the target deceleration rate. Figure 2 In FIG. 1 , the non-accelerator opening mode is indicated as the non-ACC mode.

[0035] When the deceleration object is the preceding vehicle, the target speed Vt determined by the type of the deceleration object is the preceding vehicle speed Vf. In addition, when the deceleration object is a stop object, i.e., a red light, a road sign or road surface marking for temporary parking, or an intersection without a traffic light, the target speed Vt is 0.

[0036] For example, when the speed of the vehicle 16 when the deceleration object is detected is Vp and the distance between the vehicle 16 and the deceleration object is Dr, the target deceleration Gbt is calculated according to the following formula (1). The distance Dr between the vehicle 16 and the deceleration object is estimated based on the detection result of the deceleration object detection device 56. Gbt=(Vp-Vt) / Dr……(1)

[0037] In addition, when the deceleration object is detected by the deceleration object detection device 56 under the condition that the accelerator opening Acc is greater than the reference value Accc, the deceleration control mode is set to the accelerator opening mode, and the vehicle 16 is decelerated according to the accelerator opening. When the change timing is reached, the mode of the deceleration auxiliary control is changed from the accelerator opening mode to the non-accelerator opening mode that decelerates the vehicle 16 based on the target deceleration Gbt.

[0038] In the embodiment, the ROM of the driving assistance ECU 50 stores Figure 2 The flowchart shown in the figure corresponds to a deceleration assist control program. The CPU of the driving assist ECU 50 performs the deceleration assist control according to the program. Deceleration Assist Control

[0039] Next, refer to Figure 2 The flowchart shown in the figure will explain the deceleration assist control routine in the embodiment. Figure 2 The deceleration assist control in the flowchart shown is repeatedly executed at predetermined time intervals when the deceleration assist switch 74 is turned on.

[0040] In addition, in the following description, the Figure 2 The deceleration assist control in the flowchart shown is simply referred to as “this control.” Before starting this control, a flag Foff indicating whether the mode is changed to the deceleration assist control is reset to 0 (indicating that the mode is before change).

[0041] First, in S10, the CPU determines whether there is a deceleration object in front of the vehicle 16, that is, whether the deceleration object is detected by the deceleration object detection device 56. When the CPU makes a negative determination, it temporarily ends the control, and when it makes a positive determination, it advances the control to step S20. In particular, when the CPU makes a negative determination under the condition that the flag Foff is 1, the flag Foff is reset to 0.

[0042] In addition, when the deceleration object is a preceding vehicle and the relative speed Vr of the vehicle 16 to the preceding vehicle is a negative value, a negative determination is made in S10. In addition, in the case where a preceding vehicle changes its route, a negative determination is made and there is a target deceleration Vbt calculated in S20 described later, the target deceleration Vbt is deleted. In addition, in the case where the road is a curved road, when the curvature radius of the curved road is less than the reference radius, it can be determined that the curved road is a deceleration object. The reference radius can be variably set according to the vehicle speed, so that the higher the vehicle speed, the smaller the reference radius.

[0043] In S20 , the CPU calculates a target deceleration rate Gbt for making the vehicle speed V when the vehicle 16 reaches the position of the deceleration target equal to the target vehicle speed Vt determined by the type of the deceleration target, and sets the timing of the mode change according to the type of the deceleration target.

[0044] The time from the first detection of the deceleration target to the time when the vehicle 16 decelerates at the target deceleration rate Gbt and reaches the position of the deceleration target is te, and the time from the first detection of the deceleration target to the timing of the mode change is tc. A ratio Rec of time tc to time te is preset for each deceleration target.

[0045] In the embodiment, the time te is calculated based on the detection result of the deceleration object detection device 56, and the time te is calculated based on the detection result of the deceleration object detection device 56. Figure 3 or Figure 4 The ratio Rec is determined by the flowchart shown in FIG. 1. Furthermore, by determining the time tc as the product of the time te and the ratio Rec, the timing of the mode change is determined according to the type of the deceleration object.

[0046] In the embodiment, the ratio Rec for the preceding vehicle on a level road is 1, and the ratio Rec for the preceding vehicle on an uphill road is 0.8. The ratio Rec for the parking object is 0.7 when the driver is not performing a steering operation, and is 0.5 when the driver is performing a steering operation. Whether the driver is performing a steering operation can be determined based on the steering angle θ and its rate of change, that is, the steering angular velocity θd, in a manner known in the art.

[0047] In S40, the CPU determines whether the accelerator is on, that is, whether the accelerator opening degree Acc exceeds the reference value Accc. When the CPU makes an affirmative determination, the control proceeds to S60, and when the CPU makes a negative determination, the control proceeds to S50.

[0048] In S50, the CPU performs deceleration control when the accelerator is closed, that is, the deceleration control when the accelerator opening Acc is less than the reference value Accc. For example, the CPU calculates the target braking force Fbt of the vehicle 16 based on the target deceleration Gbt, controls the deceleration device 30 in such a way that the braking force Fb of the vehicle becomes the target braking force Fbt, and thus performs deceleration control in such a way that the deceleration of the vehicle becomes the target deceleration Gbt.

[0049] In S60 , the CPU determines whether the flag Foff is 1, that is, whether the mode of the deceleration assist control has been changed. If the CPU makes an affirmative determination, the control proceeds to S100 , and if the CPU makes a negative determination, the control proceeds to S70 .

[0050] In S70, the CPU determines whether the time elapsed since the first detection of the deceleration object is greater than time tc to determine whether the deceleration assist control mode needs to be changed. If the CPU makes an affirmative determination, the control proceeds to S90, and if the CPU makes a negative determination, the control proceeds to S80.

[0051] In S80, the CPU performs a deceleration control of the vehicle according to the accelerator opening so that the greater the decrease in the accelerator opening Acc, the higher the deceleration of the vehicle 16. The mode of the deceleration assist control based on the deceleration control is Figure 2 and the following FIG. 5A to FIG. 5C In the figure, it is indicated as the ACC mode. In addition, when the accelerator opening degree Acc is increased, the deceleration of the vehicle is not controlled.

[0052] In S90, the CPU sets the flag Foff to 1. In S100, the CPU performs deceleration control so that the vehicle deceleration becomes the target deceleration Gbt, similar to the deceleration control during accelerator OFF. Figure 2 and the following Figure 5B , Figure 5C Indicates non-ACC mode.

[0053] In S110, the CPU determines whether the termination condition of the deceleration assist control is satisfied, that is, whether the deceleration control should be terminated. When the CPU makes a negative determination, the control is temporarily terminated, and when the CPU makes a positive determination, the control proceeds to step S120. In addition, when it is determined that the vehicle speed V of the vehicle 16 is below the target vehicle speed Vt, or when it is determined that the duration of the deceleration control is above te, it is determined that the termination condition of the deceleration assist control is satisfied.

[0054] In S120 , the CPU resets the flag Foff to 0, and when the target deceleration Gbt, the time te, and the time tc are calculated, deletes them, and temporarily terminates the present control.

[0055] Furthermore, when the drive device 60 includes the regeneration device 66 , at least a part of the braking force in the deceleration control in S50 , S80 , and S100 may be the regenerative braking force generated by the regeneration device 66 . Control determined by ratio Rec in the first embodiment

[0056] Next, refer to Figure 3 The flowchart shown in FIG. 1 illustrates a subroutine for determining the ratio Rec in the first embodiment.

[0057] In S22, the CPU determines whether the deceleration target is a preceding vehicle. When the CPU makes a negative determination, the control proceeds to S30, and when the CPU makes an affirmative determination, the control proceeds to S24.

[0058] In S24, the CPU determines whether the road on which the vehicle 16 is traveling is an uphill road. When the CPU makes a negative determination, the CPU determines the ratio Rec to be 1 in S26, and when the CPU makes a positive determination, the CPU determines the ratio Rec to be 0.8 in S28. In addition, the determination of whether the road is an uphill road can be based on, for example, Figure 1 The control may be performed based on information from a navigation device (not shown) or based on the relationship between the braking and driving force of the vehicle 16 and the acceleration and deceleration of the vehicle.

[0059] In S30 , the CPU determines whether the deceleration target is an intersection and the driver is steering. If the CPU makes a negative determination, the CPU determines the ratio Rec to 0.7 in S34 , and if the CPU makes an affirmative determination, the CPU determines the ratio Rec to 0.5 in S36 . Control determined by ratio Rec in the second embodiment

[0060] Next, refer to Figure 4 The flowchart shown in FIG. 1 is used to explain the subroutine for determining the ratio Rec in the second embodiment. Figure 4 and Figure 3 As can be seen from the comparison, S22 to S28 and S34, S36 are performed in the same manner as the corresponding steps in the first embodiment.

[0061] In S30 , the CPU performs the same determination as in the first embodiment, but advances the control to S36 when an affirmative determination is made, and advances the control to S32 when a negative determination is made.

[0062] In S32, the CPU determines whether there are multiple main reasons for the mode change. When the CPU makes a negative determination, the control proceeds to S34, and when the CPU makes an affirmative determination, the control proceeds to S36. For example, when the road ahead of the vehicle is a curved road and there is a red light ahead, it can be determined that there are multiple main reasons for the mode change. Examples of operations of the first and second embodiments

[0063] Next, when the deceleration object detection device 56 detects a deceleration object in front of the vehicle 16 while the accelerator is on, refer to FIG. 5A to FIG. 5C , examples of the operations of the first and second embodiments are described.

[0064] in addition, FIG. 5A to FIG. 5C Examples of changes in the vehicle speed V of the vehicle 16 are shown for the following cases C1 to C3, respectively. FIG. 5A to FIG. 5C In FIG. 1 , the dotted line and the dashed line show an example in which the average deceleration of the deceleration control in the accelerator opening pattern is smaller and larger than the target deceleration Gbt calculated when the deceleration object is detected, respectively. C1. When the vehicle ahead is the one to be decelerated Figure 5A )

[0065] If the road is not an uphill road, affirmative determination and negative determination are made in S22 and S24, respectively, and in S26, the ratio Rec is determined to be 1. Then, the time tc is the same as the time te, so the deceleration assist control is performed in the accelerator opening mode, and the mode is not changed from the non-accelerator opening mode to the accelerator opening mode.

[0066] The deceleration of the vehicle 16 is controlled according to the accelerator opening Acc until the elapsed time reaches the time te. When the elapsed time reaches the time te, an affirmative determination is made in S110, and the deceleration assist control ends. FIG. 5A to FIG. 5CIn FIG. 1 , a two-dot chain line shows a change in vehicle speed V when the deceleration of the vehicle is controlled in the non-accelerator opening mode based on the target deceleration Gbt calculated when a deceleration object is detected.

[0067] In addition, when the deceleration target is the preceding vehicle and the road is an uphill road, the time tc is set to 0.8te. Figure 5A Although not shown, the deceleration of the vehicle 16 is controlled according to the accelerator opening Acc until the elapsed time reaches time tc. When the elapsed time reaches time tc, the mode is changed to the non-accelerator opening mode, and the deceleration is controlled to reach the target deceleration Gbt until the elapsed time reaches time te. C2. When the deceleration target is a parking object ( Figure 5B )

[0068] As an example when the deceleration target is a parking object, Figure 6 The diagram shows a situation in which there is a T-junction 80 as a deceleration target in front of the vehicle 16 , and the vehicle 16 is traveling on a non-priority road 82 and is approaching a priority road 84 .

[0069] When the deceleration object is a parking target, negative determinations are made in S22 and S30, and in S34, the ratio Rec is determined to be 0.7 and the time tc is set to 0.7te. Figure 5B As shown by the dashed line and the dashed line, the deceleration of the vehicle 16 is controlled according to the accelerator opening Acc until the elapsed time reaches the time tc. When the elapsed time reaches the time tc, the mode is changed to the non-accelerator opening mode, and the deceleration is controlled to reach the target deceleration Gbt until the elapsed time reaches the time te and the vehicle speed V reaches 0. C3. When the deceleration target is an intersection and the driver is steering ( Figure 5C )

[0070] A negative determination is made in S22, an affirmative determination is made in S30, and in S36, the ratio Rec is determined to be 0.5 and the time tc is set to 0.5te. Figure 5C As shown by the dotted line and the one-dot chain line in , the deceleration of the vehicle 16 is controlled in the same manner as in the case of C2 except that the mode change from the accelerator opening mode to the non-accelerator opening mode is earlier than in the case of C2. C4. When the deceleration target is multiple parking objects ( Figure 5C )

[0071] exist Figure 4Negative determination is made in S22 and S30, and affirmative determination is made in S32. In S36, the ratio Rec is determined to be 0.5, and the time tc is set to 0.5te. Then, the deceleration of the vehicle 16 is controlled in the same manner as in the case of C3.

[0072] As can be seen from the above description, according to the embodiment, a target deceleration Gbt is calculated for making the vehicle speed V of the vehicle 16 when it reaches the position of the deceleration object become the target vehicle speed Vt determined by the type of the deceleration object, and the timing of the mode change is set according to the type of the deceleration object. In addition, when it is determined that it is the timing of the mode change, the mode is changed from the accelerator opening mode to the non-accelerator opening mode that decelerates the vehicle based on the target deceleration.

[0073] Therefore, the deceleration of the vehicle is first controlled according to the accelerator opening in the accelerator opening mode, and when it is determined that it is time to change the mode, it is automatically controlled according to the target deceleration in the non-accelerator opening mode. Therefore, after the mode is changed, the driver can control the vehicle speed to the desired speed without controlling the amount of depression of the accelerator pedal. Therefore, the effect of deceleration assistance can be improved by starting the deceleration control in advance, and the vehicle speed can be controlled to the desired speed more easily than before.

[0074] In addition, according to the embodiment, a target deceleration is calculated for making the vehicle speed a target speed determined by the type of deceleration object, and the timing of the mode change is set according to the type of deceleration object (S20). Therefore, the vehicle speed can be easily controlled to a desired speed regardless of the type of deceleration object, and the mode change can be performed at a timing corresponding to the type of deceleration object.

[0075] Furthermore, according to the embodiment, when it is determined that the deceleration object is a parking target, that is, an object for which the vehicle needs to be stopped (S22), when it is determined that a predetermined time tc has passed since the moment when the deceleration object was first detected, it is determined that it is the timing for the mode change (S70). Thus, the mode can be changed from the accelerator opening mode to the non-accelerator opening mode when the predetermined time has passed since the moment when the deceleration object was detected.

[0076] In addition, according to the embodiment, the prescribed time tc is variably set according to the type of deceleration object and the driving condition of the vehicle (S22, S24, S30). Therefore, the timing of changing the mode from the accelerator opening mode to the non-accelerator opening mode can be variably set according to the type of deceleration object and the driving condition of the vehicle.

[0077] Furthermore, according to the embodiment, when it is determined that the steering operation is being performed (S30), the timing of the mode change is advanced (S36) compared to when it is determined that the steering operation is not being performed. Thus, when the steering operation is being performed, the timing of the mode change can be advanced, and the timing of decelerating the vehicle based on the target deceleration can be advanced. Therefore, compared to the case where the timing of the mode change is not advanced, it is possible to enable the driver to concentrate on the steering operation without controlling the accelerator opening.

[0078] Furthermore, according to the embodiment, when it is determined that there are multiple deceleration targets, the timing of the mode change is advanced compared to when it is determined that there is only one deceleration target. Therefore, when there are multiple deceleration targets, the timing of the mode change can be advanced compared to when there is only one deceleration target, and the timing of decelerating the vehicle based on the target deceleration can be advanced. Therefore, compared to the case where the timing of the mode change is not advanced, the driver can be prevented from having to control the accelerator opening.

[0079] As mentioned above, although the specific embodiment of the present invention has been described in detail, it is obvious to those skilled in the art that the present invention is not limited to the above-mentioned embodiment, and other various embodiments can be implemented within the scope of the present invention.

[0080] For example, in the above-mentioned embodiment, the prescribed time tc is variably set according to both the type of deceleration object and the driving condition of the vehicle (S22, S24, S30). However, the prescribed time may also be variably set according to one of the type of deceleration object and the driving condition of the vehicle (S22, S24, S30). In addition, the driving condition of the vehicle in the embodiment is the condition of the vehicle driving on an uphill road, but may also include other driving conditions such as the inter-vehicle distance with the preceding vehicle and weather conditions.

[0081] For example, the execution order of S22 and S30 in the first embodiment may be reversed, and the execution order of S22, S30, and S32 in the second embodiment may be reversed.

[0082] The value of the ratio Rec in the above-mentioned embodiment is merely an example and is not limited to the above-mentioned value. In addition, the ratio Rec is 1 when the deceleration target is the preceding vehicle, but it may be a value smaller than 1 and larger than 0.8.

Claims

1. A deceleration assist control device for a vehicle, comprising: an accelerator opening detection device for detecting an accelerator opening, a deceleration object detection device for detecting a deceleration object in front of a vehicle, a deceleration device for decelerating the vehicle, and a control unit for controlling the deceleration device, wherein the control unit is configured to: when a deceleration object is detected under a condition where the accelerator opening exceeds a reference value, control the deceleration device to perform deceleration assist control in an accelerator opening mode for decelerating the vehicle according to the accelerator opening, wherein: The control unit is configured to calculate a target deceleration for causing the vehicle speed to become a target speed determined by the type of deceleration object when the vehicle reaches the position of the deceleration object, set a timing for a mode change according to the type of the deceleration object, and when it is determined that it is the timing for the mode change, perform a mode change from the accelerator opening mode to a non-accelerator opening mode that decelerates the vehicle based on the target deceleration.

2. The vehicle deceleration assist control device according to claim 1, wherein: The control unit is configured to determine that it is time to change the mode when it is determined that the deceleration object is an object that requires the vehicle to stop and when it is determined that a predetermined time has passed since the deceleration object was first detected.

3. The vehicle deceleration assist control device according to claim 2, wherein: The control unit is configured to variably set the predetermined time according to at least one of a type of a deceleration target and a running condition of the vehicle.

4. The vehicle deceleration assist control device according to claim 1, wherein: The control unit is configured to advance the timing of the mode change when it is determined that the steering operation is being performed, compared to when it is not determined that the steering operation is being performed.

5. The vehicle deceleration assist control device according to claim 1, wherein: The control unit is configured to advance the timing of the mode change when it is determined that there are a plurality of deceleration targets, compared to when it is determined that there is only one deceleration target.

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