JP4304247B2 - Deceleration control device - Google Patents

Description

  The present invention relates to a deceleration control device that performs deceleration control of a vehicle that is turning on a curve.

The safe vehicle speed is calculated from the motion state and driving operation of the vehicle turning around the curve or corner, and when the actual vehicle speed reaches the safe vehicle speed, the vehicle speed is automatically reduced below the safe vehicle speed, and spin, drift-out or rollover is performed. A deceleration control device that prevents the above has been proposed (see, for example, Patent Document 1).
Japanese Patent Laid-Open No. 10-278762

Even if the vehicle is in the same turning state, the road condition (shape, etc.) after that differs depending on whether the vehicle is turning at the entrance of the curve or turning at the exit of the curve. Therefore, if the same deceleration control is performed at the entrance and exit of the curve, the driver feels uncomfortable. For example, the deceleration control performed on a curve gives the driver a feeling of stalling or poor acceleration.
Therefore, the present invention has been made in view of the above-described problems, and an object of the present invention is to provide a deceleration control device that prevents the deceleration control performed by a curve from causing a driver to feel uncomfortable.

In order to solve the above-described problems, the present invention provides a deceleration control device that performs deceleration control so as to achieve a target vehicle speed set based on a turning state when the vehicle is turning, based on a steering angle and an actual vehicle speed. The estimated yaw rate of the vehicle is calculated by the estimated yaw rate calculating means, the actual yaw rate generated in the vehicle is detected by the actual yaw rate detecting means , and the limit value of the lateral acceleration at which the vehicle can stably turn is calculated. The target vehicle speed setting means sets the target vehicle speed based on a value obtained by dividing by the larger one of the estimated yaw rate calculated by the means and the actual yaw rate detected by the actual yaw rate detection means. And this invention detects that the vehicle is traveling on the curve exit by the curve exit detection means, and when the curve exit detection means detects that the vehicle is traveling on the curve exit, Correction for adding a throttle opening corresponding lateral acceleration limit value correction amount that increases as the throttle opening increases and a vehicle speed corresponding lateral acceleration limit value correction amount that decreases as the vehicle speed increases to the lateral acceleration limit value do.
Generally, the estimated yaw rate obtained from the steering angle of the steering wheel can be detected earlier than the actual yaw rate detected by the yaw rate detecting means such as the yaw rate sensor. On the other hand, when traveling on a low μ road or the like, the vehicle behavior may change in a direction in which the actual yaw rate increases without turning the steering wheel too much. For this reason, the target vehicle speed for deceleration control is set based on the larger value of the estimated yaw rate and the actual yaw rate.

According to the present invention, since the target vehicle speed for the deceleration control is set based on the larger value of the estimated yaw rate and the actual yaw rate, the deceleration control can be intervened at an early stage . Furthermore, since the curve exit can be detected and the control amount of the deceleration control can be reduced at the detected curve exit, it is possible to prevent the driver from feeling uncomfortable with the deceleration control performed on the curve.

The best mode for carrying out the present invention (hereinafter referred to as an embodiment) will be described in detail with reference to the drawings.
FIG. 1 shows a vehicle configuration to which the present invention is applied.
This vehicle includes a control controller 2, an engine throttle control unit 3, a brake control unit 4, a yaw rate sensor 5, a wheel speed sensor 6, and a rudder angle sensor 7.
The engine throttle control unit 3 is configured to control an engine throttle (not shown) independently of an operation by a driver. The brake control unit 4 is configured to control a brake mechanism (not shown) independently of the operation by the driver.
The yaw rate sensor 5 detects the yaw rate of the vehicle. The vehicle speed pulse 6 detects the wheel speed of each wheel of the vehicle. The steering angle sensor 7 detects the steering angle of the steering wheel. These sensors 5, 6, and 7 output detection results to the controller 2.

The controller 2 is configured to control each part of the vehicle. The controller 2 controls each part based on the detection results of the sensors 5, 6 and 7. When the controller 2 is turning on a curve, the controller 2 automatically executes deceleration control. In the deceleration control, the controller 2 outputs a command signal to the engine throttle control unit 3 and the brake control unit 4 according to the target deceleration at the time of the control intervention. Thereby, the engine throttle control unit 3 controls the opening of the engine, specifically, the throttle, and the brake control unit 4 controls the brake mechanism, specifically, the brake fluid pressure.

Next, the processing of the controller 2 will be described in detail.
FIG. 2 shows the configuration of the controller 2. As shown in FIG. 2, the controller 2 includes a yaw rate calculation unit 11, a lateral acceleration limit value calculation unit 12, a target vehicle speed calculation unit 13, a target deceleration calculation unit 14, a deceleration control unit 15, a curve exit determination unit (or A corner exit determination unit) 16 and a lateral acceleration limit value correction unit 17. FIG. 3 shows the order of processing of these units. The processing content of each part of the controller 2 will be described with reference to FIG.

First, in step S1, the yaw rate calculation unit 11 calculates the yaw rate. FIG. 4 shows a configuration of the yaw rate calculation unit 11 for calculating the yaw rate. As shown in FIG. 4, the yaw rate calculation unit 11 includes a yaw rate estimation unit 21 and a select high unit 22.
First, the yaw rate calculation unit 11 estimates the yaw rate based on the vehicle speed detected by the wheel speed sensor 6 and the rudder angle detected by the rudder angle sensor 7. The yaw rate is estimated based on the vehicle speed and the steering angle by a general method. Then, the yaw rate calculation unit 11 outputs the estimated yaw rate (hereinafter referred to as a yaw rate estimation value) to the select high unit 22.

The select high unit 22 performs a select high (selection of the larger value) from the estimated yaw rate value obtained by the yaw rate calculation unit 11 and the actual yaw rate value detected by the yaw rate sensor 5.
In general, the estimated yaw rate obtained from the steering angle can be detected earlier than the actual measured yaw rate detected by the yaw rate sensor 5. However, when traveling on a low μ road or the like, the vehicle behavior may change in a direction in which the yaw rate increases without turning the steering wheel (for example, in the slow spin mode). Therefore, by performing a select high from the estimated yaw rate value and the measured yaw rate value, the measured yaw rate value can also be selected, and when the measured yaw rate value is larger, this measured yaw rate value is Select to enable early intervention of deceleration control.

The yaw rate calculation unit 11 outputs the yaw rate selected by the select high unit 22 in this way to the target vehicle speed calculation unit 13 as the yaw rate select value ψ ^* (> 0).
Subsequently, in step S2, the lateral acceleration limit value calculation unit 12 calculates a lateral acceleration limit value Yg ^* . The lateral acceleration limit value Yg ^* is a limit value of the target lateral acceleration for the vehicle to travel in the curve without spinning, drifting out or rolling over. The lateral acceleration limit value calculation unit 12 sets the target lateral acceleration Yga as the lateral acceleration limit value Yg ^* . This target lateral acceleration Yga is, for example, 0.45G. The lateral acceleration limit value calculation unit 12 then outputs the calculated lateral acceleration limit Yg ^* to the target vehicle speed calculation unit 13.

As will be described later, by applying the present invention, the lateral acceleration limit value Yg ^* is corrected when the vehicle is traveling on a curve exit.
Subsequently, in step S3, the target vehicle speed calculation unit 13 calculates the target vehicle speed V ^* . Specifically, as shown in FIG. 5, the target vehicle speed calculation unit 13 includes the yaw rate select value ψ ^* calculated by the yaw rate calculation unit 11 in step S1, and the lateral acceleration limit value calculation unit 1 in step S2.
Based on the lateral acceleration limit value Yg ^* calculated by 2 and the estimated value μ of the road surface μ, the target vehicle speed V ^* is calculated by the following equation (1).
V ^* = μ × Yg ^* / ψ ^* (1)

According to the equation (1), the target vehicle speed V ^* decreases as the road surface μ decreases. Further, the target vehicle speed V ^* decreases as the lateral acceleration limit value Yg ^* decreases. Further, the target vehicle speed V ^* decreases as the yaw rate select value ψ ^* increases.
Subsequently, in step S4, the target deceleration calculation unit 14 calculates a target deceleration Xg ^* . Specifically, the target deceleration calculation unit 14 calculates the target deceleration Xg ^* by the following equation (2).
Xg ^* = K1 × ΔV / Δt (2)

Here, ΔV is a difference value (speed deviation value) obtained by subtracting the target vehicle speed V ^* calculated by the target vehicle speed calculation unit 13 in step S3 from the vehicle speed V (ΔV = V−V ^* ), and Δt is a predetermined value. It is time and K1 is a gain.
According to the equation (2), when ΔV increases, that is, when the difference between the vehicle speed V and the target vehicle speed V ^* increases in the positive direction, the target deceleration Xg ^* also increases. In addition, when the equation (1) is used, when the yaw rate ψ ^* increases, ΔV increases, so the target deceleration Xg ^* also increases. That is, for example, the target deceleration Xg ^* increases as the curve radius increases.
The target deceleration calculation unit 14 outputs the calculated target deceleration Xg ^* to the deceleration control unit 15.
Subsequently, in step S5, the deceleration control unit 15 controls the engine throttle control unit 3 and the brake control unit 4 so that the actual deceleration becomes the target deceleration Xg ^* .

FIG. 6 shows a processing procedure of the deceleration control unit 15.
First, in step S11, the target deceleration Xg ^* and the throttle opening Acc are input to the deceleration control unit 15. The throttle opening Acc is a throttle opening corresponding to the accelerator operation amount by the driver.
Subsequently, in step S12, the deceleration control unit 15 determines whether or not the target deceleration Xg ^* is greater than zero. Here, when the target deceleration Xg ^* is greater than 0 (Xg ^* > 0), that is, when the target deceleration Xg ^* is a value that requires deceleration, the deceleration control unit 15 proceeds to step S13, and the target deceleration Xg ^*. Is less than or equal to 0 (Xg ^* ≦ 0), that is, when the target deceleration Xg ^* is a value that requires acceleration, the process proceeds to step S17.

In step S13, the deceleration control unit 15 turns on the deceleration control flag Flag (Flag = ON). Then, the deceleration control unit 15 proceeds to step S14.
In step S14, the deceleration control unit 15 determines whether the throttle opening Acc is less than a predetermined value a. Here, when the throttle opening degree Acc is less than the predetermined value a (Acc <a), the deceleration control unit 15 proceeds to step S15. When the throttle opening degree Acc is greater than or equal to the predetermined value a (Acc ≧ a), step S16 is performed. Proceed to

In step S15, the deceleration control unit 15 controls the brake by the brake control unit 4 so that the target deceleration Xg ^* is obtained. Specifically, the brake control unit 4 controls the brake fluid pressure. On the other hand, the deceleration control unit 15 keeps the throttle fully open. That is, the deceleration control unit 15 does not control the engine by the engine throttle control unit 3, but maintains the throttle opening that the driver is operating, that is, the throttle is fully opened. And the deceleration control part 15 performs the process from said step S11 again.

In step S16, the deceleration control unit 15 controls the engine by the engine throttle control unit 3 so that the target deceleration Xg ^* is obtained, and further controls the brake by the brake control unit 4.
Specifically, the brake is operated by the brake control unit 4 (the brake fluid pressure is increased), while the throttle opening is suppressed by the engine throttle control unit 3 against the accelerator operation by the driver. At this time, after the brake is operated by the brake control unit 4 at a certain time, that is, after the brake fluid pressure is increased to a certain value, the brake fluid pressure is reduced and finally set to zero. The deceleration control unit 15 controls the engine and the brake by the engine throttle control unit 3 and the brake control unit 4 as described above to obtain the target deceleration Xg ^* . And the deceleration control part 15 performs the process from said step S11 again.

On the other hand, in step S17, the deceleration control unit 15 determines whether or not the deceleration control flag Flag is ON. Here, the deceleration control unit 15 proceeds to step S18 when the deceleration control flag Flag is ON (Flag = ON), and proceeds to step S21 when the deceleration control flag Flag is not ON.
In step S18, the deceleration control unit 15 controls the engine throttle control unit 3 and the brake control unit 4 to reduce the brake fluid pressure and recover the throttle. Specifically, while the brake fluid pressure is gradually reduced by the brake control unit 4, the throttle opening is gradually returned by the engine throttle control unit 3 until it reaches a value corresponding to the driver's accelerator operation amount. To go.

  Subsequently, in step S19, the deceleration control unit 15 determines whether or not the brake fluid pressure reduction and the throttle recovery have been completed. Here, when the brake fluid pressure reduction and the throttle recovery are completed, the deceleration control unit 15 proceeds to step S20, sets the deceleration control flag Flag to OFF, and performs the processing from step S11 again. In addition, when the brake fluid pressure reduction and the throttle recovery are not completed, the deceleration control unit 15 performs the processing from step S11 again without turning off the deceleration control flag Flag.

Further, the deceleration control unit 15 turns off the deceleration control flag Flag in step S21, and performs the processing from step S11 again.
Thus, the deceleration control unit 15 controls the engine throttle control unit 3 and the brake control unit 4 so that the actual deceleration becomes the target deceleration Xg ^* .
By such processing, for example, the following deceleration control is performed.

When the target deceleration Xg ^* becomes larger than 0 (Xg ^* > 0) due to the vehicle turning on a curve, the deceleration control is operated so as to be the target deceleration Xg ^* . At this time, when the throttle opening Acc by the driver is larger than the predetermined value a, the brake (brake fluid pressure) is controlled in the pressure reducing direction, and finally the brake fluid pressure is controlled to be zero. On the other hand, engine throttle control is performed (step S16).

Further, when the vehicle turns on the curve, the target deceleration Xg ^* becomes larger than 0 (Xg ^* > 0), but when the throttle opening Acc by the driver is smaller than a predetermined value a, for example, the driver When the accelerator is not stepped on, deceleration control by only brake control, that is, deceleration control is performed so that the brake hydraulic pressure is increased to the target deceleration Xg ^* (step S15).

When the target deceleration Xg ^* becomes smaller than 0 (Xg ^* ≦ 0), for example, when the vehicle goes through a curve, the brake (brake hydraulic pressure) is controlled in the pressure reducing direction, while the driver's accelerator operation amount The accelerator opening is recovered to the amount corresponding to. Then, the deceleration control is completed in a state where the accelerator opening is completely recovered (step S18).
For example, in terms of the relationship with the road surface μ, this deceleration control becomes easier to intervene as the road surface μ becomes lower. In terms of the relationship with the lateral acceleration limit value Yg ^* , the deceleration control becomes easier to intervene as the lateral acceleration limit value Yg ^* becomes smaller. In terms of the relationship with the yaw rate select value ψ ^* , this deceleration control becomes easier to intervene as the yaw rate select value ψ ^* increases.

Next, correction of the lateral acceleration limit value Yg ^* that is performed when the vehicle is traveling on a curve exit will be described.
FIG. 7 shows a processing procedure of curve exit determination by the curve exit determination unit 16.
First, in step S31, the curve exit determination unit 16 obtains the absolute value abs (str) of the steering angle str, and substitutes the steering angle absolute value abs (str) for the current steering angle value str (t).
Subsequently, in step S32, the curve exit determination unit 16 subtracts the immediately preceding steering angle value str (t-1) from the current steering angle value str (t) obtained in step S31 to obtain a difference value Δstr.
When t is the sampling time, the current steering angle value str (t) is the latest steering angle value, and the immediately preceding steering angle value str (t-1) is immediately before the current steering angle value str (t). The obtained steering angle value.

  Subsequently, in step S33, the curve exit determination unit 16 determines whether or not the difference value Δstr obtained in step S32 is less than zero. Here, the case where the difference value Δstr is less than 0 (Δstr <0) is a case where the steering angle is decreasing, that is, a case where the driver is turning back the steering wheel, and the difference value Δstr is 0. The above case (Δstr ≧ 0) is the case where the rudder angle is maintained or the rudder angle is increasing, and the case where the driver is not operating the steering wheel or the case where the driver is increasing the steering wheel. is there. The curve exit determination unit 16 proceeds to step S34 when the difference value Δstr is less than 0 (Δstr <0), and proceeds to step S35 when the difference value Δstr is 0 or more (Δstr ≧ 0).

In step S34, the curve exit determination unit 16 turns on the curve exit determination flag Flag_out (Flag_out = ON). In step S35, the curve exit determination unit 16 turns off the curve exit determination flag Flag_out (Flag_out = OFF).
As shown in FIG. 7, the curve exit determination unit 16 performs a curve exit determination process. If the driver has turned back the steering wheel by the curve exit determination processing, the curve exit determination flag Flag_out is turned ON (Flag_out = ON), and the driver is not operating the steering wheel or the driver Is increasing the steering wheel, the curve exit determination flag Flag_out is turned off (Flag_out = OFF).

  When trying to stop the turning movement of the vehicle because the vehicle is approaching the exit of the curve, the driver turns back the steering wheel. For this reason, when the driver is turning back the steering wheel, the curve exit determination flag Flag_out is set to ON, assuming that the vehicle is approaching the exit of the curve. On the other hand, the driver does not operate the steering wheel or increases the steering wheel on a straight road (including a case where the vehicle completely passes through the curve) or the curve. For this reason, when the driver is not operating the steering wheel or when the driver has increased the steering wheel, it is assumed that the vehicle is traveling on a straight road or inside a curve, and the curve exit determination flag Flag_out is turned off. I have to.

FIG. 8 shows a processing procedure for correcting the lateral acceleration limit value by the lateral acceleration limit value correcting unit 17. By the process of correcting the lateral acceleration limit value, the lateral acceleration limit value Yg ^* is corrected in response to the vehicle traveling on the curve exit.
First, in step S41, the lateral acceleration limit value correction unit 17 determines the curve exit determination flag F.
It is determined whether lag_out is ON. Here, if the curve exit determination flag Flag_out is ON (Flag_out = ON), the lateral acceleration limit value correction unit 17 proceeds to step S42. If the curve exit determination flag Flag_out is not ON (Flag_out = OFF), the lateral acceleration limit value correction unit 17 proceeds to step S43. move on.

In step S42, the lateral acceleration limit value correcting unit 17, the correction amount for correcting the lateral acceleration limit Yg ^* (hereinafter referred to as a first lateral acceleration limit value correction amount.) The counts up YGE. Then, the lateral acceleration limit value correction unit 17 proceeds to step S44. Further, in step S43, lateral acceleration limitation value correcting unit 17 counts down the first lateral acceleration limit value correction amount YGE. Then, the lateral acceleration limit value correction unit 17 proceeds to step S44. Here, the first lateral acceleration limit value correction amount Yge, the initial value is 0, which is a value that changes by a predetermined amount by the count-up or count down.

At step S44, lateral acceleration limitation value correcting unit 17 determines a first lateral acceleration limit value correction amount Yge whether less than 0. Here, the lateral acceleration limit value correcting unit 17, when the first lateral acceleration limit value correction amount YGE is less than 0 (Yge <0), the process proceeds to step S45, the first lateral acceleration limit value correction amount YGE 0 In the above case (Yge ≧ 0), the process proceeds to step S46.
In step S45, lateral acceleration limitation value correcting section 17, a first lateral acceleration limit value correction amount Yge to 0. Then, the lateral acceleration limit value correction unit 17 proceeds to step S48.

In step S46, lateral acceleration limitation value correcting section 17, the first lateral acceleration limit value correction amount Yge is equal to or greater than a predetermined value (upper limit value) E. Here, the lateral acceleration limit value correcting unit 17, when the first lateral acceleration limit value correction amount YGE is larger than the predetermined value E (Yge> E), the process proceeds to step S47, the first lateral acceleration limit value correction amount YGE Is less than or equal to the predetermined value E (Yge ≦ E), the process proceeds to step S48.

At step S47, the lateral acceleration limiting value correction unit 17 substitutes the predetermined value E to a first lateral acceleration limit value correction amount YGE. Then, the lateral acceleration limit value correction unit 17 proceeds to step S48.
At step S48, the lateral acceleration limiting value correction unit 17, by the following equation (3) using a first lateral acceleration limit value correction amount YGE, lateral acceleration limit lateral acceleration limit value calculation unit 12 is calculated in step S2 The value Yg ^* is corrected.
Yg ^* = Yga + Yge (3)

As shown in FIG. 8, the lateral acceleration limit value correction unit 17 performs target lateral acceleration correction processing. By the process of the target deceleration correction, if the curve exit determination flag Flag_out is ON, the first lateral acceleration limit value correction amount Yge is counted up to be larger, increasing the limit of the predetermined value E. Moreover, the curve exit determination flag Flag_out if OFF, the first lateral acceleration limit value correction amount Yge is counted down so as to be smaller, reducing the zero limit.
Thus, only the period of the curve exit determination flag Flag_out has been turned ON, the first lateral acceleration limit value correction amount Yge increases, as a result, the larger the lateral acceleration limit value Yg ^*.
The relationship with the target deceleration Xg ^* which is a target value for controlling the engine throttle control unit 3 and the brake control unit 4 is as follows.

As described above, the target vehicle speed V ^* is varied in accordance with the lateral acceleration limit value Yg ^*, for example, the lateral acceleration limit value Yg ^* is smaller as the target vehicle speed V ^* is reduced (the (1) see). Then, the target deceleration Xg ^* changes according to the target vehicle speed ^{V *,} target deceleration Xg ^* example, as the target vehicle speed ^{V *} is small increases (see (2) above).
Therefore, the target deceleration Xg ^* changes according to the lateral acceleration limit value Yg ^* , and the lateral acceleration limit value Yg
g ^* becomes higher target deceleration Xg ^* becomes larger smaller, the lateral acceleration limit value Yg ^* is larger as the target deceleration Xg ^* becomes smaller.

Therefore, when the curve exit determination flag Flag_out is ON, that is, when the driver is turning back the steering wheel, the lateral acceleration limit value Yg ^* is corrected so as to increase. As a result, the target deceleration is obtained. Correction is made in the direction of decreasing Xg ^* . As a result, when the vehicle is traveling at the exit of the curve, the engine throttle control unit 3 and the brake control unit 4 suppress the deceleration control or suppress the intervention of the deceleration control. A rise is possible. Thereby, it is possible to prevent the deceleration control from giving the driver a sense of restraint or discomfort at the exit of the curve.

As a result, the deceleration control device performs deceleration control with a normal control amount in a curve far from the exit, thereby enabling the vehicle to travel safely, and restraining the deceleration control to the driver near the exit of the curve. It is possible to prevent a feeling of incongruity and discomfort.
The embodiment of the present invention has been described above. However, the present invention is not limited to being realized as the above-described embodiment.

  That is, in the above-described embodiment, the exit of the curve is determined based on the steering angle of the steering wheel obtained by the driving operation of the driver (see FIG. 7). However, it is not limited to this. That is, the exit of the curve may be determined based on another driving operation of the driver. For example, the exit of the curve may be determined based on the driver's acceleration operation as the driver's driving operation. FIG. 9 shows a processing procedure for curve exit determination based on the driver's acceleration operation.

First, in step S51, the curve exit determination unit 16 obtains the absolute value abs (str) of the steering angle str and substitutes the steering angle absolute value abs (str) for the steering angle value str_a.
Subsequently, at step S52, the curve exit determination unit 16 subtracts the value mc (t-1) immediately before the master cylinder pressure from the master cylinder pressure mc (t) of the brake to obtain a difference value Δmc.
The value mc (t-1) immediately before the master cylinder pressure is the master cylinder pressure obtained immediately before the current value mc (t) of the master cylinder pressure when t is the sampling time.
Subsequently, in step S53, the curve exit determination unit 16 determines whether or not the steering angle value str_a obtained in step S51 is greater than a predetermined value b. Here, the case where the steering angle value str_a is larger than the predetermined value b is a case where the steering wheel is in a state of being cut by a certain amount.

The curve exit determination unit 16 proceeds to step S54 when the steering angle value str_a is larger than the predetermined value b (str_a> b), and proceeds to step S57 when the steering angle value str_a is equal to or smaller than the predetermined value b (str_a ≦ b). .
Subsequently, in step S54, the curve exit determination unit 16 determines whether or not the brake brsw is ON. Here, the curve exit determining unit 16 proceeds to step S55 when the brake brsw is ON (brksw = ON), and proceeds to step S57 when the brake brsw is not ON (brksw = OFF).

In step S55, the curve exit determination unit 16 determines whether or not the difference value Δmc of the master cylinder pressure obtained in step S52 is less than zero. Here, the case where the difference value Δmc of the master cylinder pressure is less than 0 is a case where the brake is released from the applied state.
When the master cylinder pressure difference value Δmc is less than 0 (Δmc <0), the curve exit determination unit 16 proceeds to step S56. When the master cylinder pressure difference value Δmc is 0 or more (Δmc ≧ 0), the curve exit determination unit 16 proceeds to step S57. Proceed to

In step S56, the curve exit determination unit 16 determines the curve exit determination flag Flag_ou.
t is turned ON (Flag_out = ON). In step S57, the curve exit determination unit 16 turns off the curve exit determination flag Flag_out (Flag_out = OFF).
As shown in FIG. 9, the curve exit determination unit 16 performs a curve exit determination process. When the driver has turned the steering wheel by a certain amount (step S53) and returns from the state where the driver has depressed the brake pedal (step S54, step S55). The curve exit determination flag Flag_out is turned on (Flag_out = ON), and the driver does not turn the steering wheel by a certain amount, the driver does not depress the brake pedal, or the driver depresses the brake pedal. When the return operation of the brake pedal is not performed, the curve exit determination flag Flag_out is turned off (Flag_out = OFF).

  The driver performing the operation of releasing the brake with the steering wheel turned off is a case where the driver is going to accelerate the host vehicle because the host vehicle approaches the exit of the curve. For this reason, when the driver performs the operation of releasing the brake while the steering wheel is turned off, the driver is trying to accelerate the host vehicle. Is approaching the exit of the curve, the curve exit determination flag Flag_out is set to ON. When such an operation is not performed, the curve exit determination flag Flag_out is set to OFF, for example, assuming that a curve has been exited.

Thus, the curve exit may be determined based on the driver's acceleration operation. Furthermore, although the driver's intention to accelerate is estimated based on the steering wheel operation and the brake operation, the curve exit can be determined by complexly judging from various operation information of the driver. Good.
Moreover, it is not limited to determining the exit of a curve based on a driver | operator's driving operation, You may determine a curve exit based on a vehicle behavior. For example, the exit of the curve may be determined based on vehicle behavior such as the yaw rate or lateral acceleration of the host vehicle. For example, in this case, when the yaw rate is decreasing or when the lateral acceleration is decreasing, it is determined as the exit of the curve.

In the above-described embodiment, the case where the target deceleration Xg ^* is calculated by the above equation (2) has been described. However, it is not limited to this. For example, the target deceleration Xg ^* may be calculated using the following equation (4).
Xg ^* = (K2 × ΔV + K3 × dΔV) / Δt
ΔV = V−V ^*
dΔV = ΔV−ΔVZ where ΔV> 0
... (4)
Here, ΔVZ is a past value of ΔV (sampling value immediately before ΔV). Δt is a predetermined time, which is a time until the speed deviation value becomes zero. K2 and K3 are gains. Therefore, since dΔV is a difference value of the speed deviation value, the target deceleration Xg ^* is a value obtained in consideration of such a difference value dΔV of the speed deviation value.

As a result, according to the equation (1) and the equation (4), the increase amount of the target deceleration Xg ^{* with} respect to the change amount of the yaw rate select value ψ ^* also increases. Therefore, for example, when the driver performs a fast steering operation, the target deceleration reacts immediately in response to it and increases instantaneously. As a result, the deceleration control can be quickly performed in accordance with the driver's steering operation.

Further, in the above-described embodiment, the case where the lateral acceleration limit value is corrected using FIG. 8 has been described. However, it is not limited to this. For example, the lateral acceleration limit value Yg ^* may be corrected using the following equation (5).
Yg ^* = Yga + Ygb + Ygc + Ygd (5)
Here, Ygb the correction amount based on the throttle opening (accelerator pedal angle) (hereinafter, referred to as a second lateral acceleration limit value correction amount.), And the correction amount Ygc is based on the vehicle speed (hereinafter, a third lateral acceleration that limit value correction amount.), and, YGD the correction amount based on the road gradient (hereinafter, is referred to.) the fourth lateral acceleration limit value correction amount.

10 to 12 show the characteristics of the second through fourth lateral acceleration limit value correction amount.
As shown in FIG. 10, a second lateral acceleration limit value correction amount Ygb increases in proportion to the throttle opening (accelerator pedal angle). Further, as shown in FIG. 11, the third lateral acceleration limit value correction amount Ygc is until a certain speed the vehicle speed, but a constant value, beyond which a constant speed, smaller in accordance with the vehicle speed. Further, as shown in FIG. 12, the fourth lateral acceleration limit value correction amount Ygd it comes to size where there is a road gradient of the travel path, increases in accordance with the road gradient.

Therefore, the lateral acceleration limit value Yg ^* is corrected so as to increase as the throttle opening (accelerator pedal angle) increases, the vehicle speed decreases, or the road gradient increases.
Such a lateral acceleration limit value Yg ^* is performed when the curve exit determination flag Flag_out is ON, as in the process of FIG. For example, although corrected lateral acceleration limitation value Yg ^* by the first lateral acceleration limit value in step S48 the correction amount Yge 8, this time, these second through fourth lateral acceleration limit value correction amount Ygb, Correction using Ygc and Ygd is also performed at the same time.

For example, the driver tries to accelerate at a curve exit. Therefore, by increasing the lateral acceleration limit value Yg ^* as the throttle opening (accelerator pedal angle) increases, the driver's intention to accelerate can be reflected in the correction of the lateral acceleration limit value Yg ^*. it can. Accordingly, the vehicle can suppress the deceleration control at the curve exit reflecting the driver's intention and accelerate smoothly.

In addition, when turning with a small radius, such as a U-turn, the driver tries to do it at a low speed. Therefore, by increasing the lateral acceleration limit value Yg ^* as the vehicle speed decreases, the driver's intention to operate the vehicle at a low speed can be reflected in the correction of the lateral acceleration limit value Yg ^* . Accordingly, it is possible to smoothly perform the U-turn or the like by suppressing the deceleration control from intervening in the U-turn or the like reflecting the driver's intention.

Also, if the accelerator is released on an uphill, the vehicle will decelerate more than when traveling on a flat road. Therefore, by increasing the lateral acceleration limit value Yg ^* as the road gradient becomes steep, it is possible to prevent the vehicle from decelerating greatly even when the accelerator is released on an uphill. Therefore, even in the case of an uphill curve, the driver's intention is reflected to suppress deceleration control at the curve exit and accelerate smoothly.
Further, the target vehicle speed V ^* calculated in step S4 may be corrected in consideration of the fact that the road surface μ is an estimated value.

FIG. 13 shows the procedure for correcting the target vehicle speed V ^* . For example, the target vehicle speed calculation unit 13 performs this correction.
First, in step S61, the target vehicle speed calculation unit 13 obtains the absolute value abs (Yg) of the lateral acceleration Yg detected by a lateral acceleration sensor (not shown), and uses this lateral acceleration absolute value abs (Yg) as the current lateral acceleration Yg (t ).
Subsequently, in step S62, the target vehicle speed calculation unit 13 determines whether or not the current lateral acceleration Yg (t) obtained in step S61 is less than the immediately preceding lateral acceleration Yg (t-1). The current lateral acceleration Yg (t) is the latest lateral acceleration, where t is the sampling time, and the immediately preceding lateral acceleration Y
g (t-1) is a lateral acceleration obtained immediately before the current lateral acceleration Yg (t). That is, the target vehicle speed calculation unit 13 determines whether or not the lateral acceleration Yg has increased in step S62.

  Here, the target vehicle speed calculation unit 13 reduces the lateral acceleration Yg when the current lateral acceleration Yg (t) is less than the immediately preceding lateral acceleration Yg (t−1) (Yg (t) <Yg (t−1)). If the current lateral acceleration Yg (t) is greater than or equal to the previous lateral acceleration Yg (t−1) (Yg (t) ≧ Yg (t−1)), that is, the lateral acceleration Yg increases. If so, the process proceeds to step S64.

In step S63, the target vehicle speed calculation unit 13 counts down the current lateral acceleration Yg (t) by a predetermined amount. Then, the target vehicle speed calculation unit 13 proceeds to step S64.
In step S64, the target vehicle speed calculation unit 13 determines whether the increase / decrease amount of the throttle opening Acc is greater than 5%. That is, the target vehicle speed calculation unit 13 determines whether or not the driver is operating the accelerator by a certain amount.

  Here, when the increase / decrease amount of the throttle opening Acc is larger than 5% (the increase / decrease amount of Acc> 5%), that is, when the driver is operating the accelerator by a certain amount, the target vehicle speed calculation unit 13 proceeds to Step S65. When the increase / decrease amount of the throttle opening Acc is 5% or less (the increase / decrease amount of Acc ≦ 5%), that is, when the driver does not operate the accelerator by a certain amount, the process proceeds to step S66.

In step S66, the target vehicle speed calculation unit 13 calculates the target vehicle speed V ^* using the equation (1). That is, the target vehicle speed calculation unit 13 calculates the target vehicle speed V ^* without correcting it.
On the other hand, in step S65, the target vehicle speed calculation unit 13 calculates the target vehicle speed V ^* by the following equation (6).
V ^* = Yg (t) / ψ ^* (6)
That is, as can be seen by comparing the equation (6) with the equation (1), in step S65, the value of μ × Yg ^* is replaced with the lateral acceleration actually generated in the vehicle, and the target vehicle speed V ^*. Is calculated.

As shown in FIG. 13, the target vehicle speed calculation unit 13 corrects the target vehicle speed V ^* . With this correction processing of the target vehicle speed V ^* , when the driver is operating the accelerator by a certain amount, the target vehicle speed V ^* is calculated without using the road surface μ according to the equation (6).
As described above, the road surface μ used in the equation (1) is an estimated value, and may be far from the actual road surface μ due to an estimation error. For example, when the estimated road surface μ is much smaller than the actual road surface μ, the target vehicle speed V ^* is estimated as a small value according to the equation (1). In this case, the target deceleration Xg ^* is calculated as a large value according to the equation (2), and as a result, the deceleration due to the deceleration control increases. As a result, the driver feels a sense of restraint through the deceleration control.

In this way, when the estimated road surface μ used in the deceleration control is much smaller than the actual road surface μ, the driver feels that the actual road surface μ The vehicle may be accelerated by performing a driving operation such as an accelerator operation even during a turn according to the road surface μ.
Therefore, when the driver operates the accelerator by a certain amount during a turn, it is estimated that the estimation error is increased in the estimated value of the road surface μ, and without using the estimated value of the road surface μ, A target vehicle speed V ^* is calculated. At this time, the target vehicle speed V ^* is calculated using the actual lateral acceleration Yg generated in the host vehicle by the accelerator operation as a target value (see the equation (6)).

Thereby, even if an estimation error occurs in the estimated value of the road surface μ, the target vehicle speed V ^* can be calculated based on the lateral acceleration Yg at which the host vehicle can turn on the curve. As a result, even when an estimation error occurs in the estimated value of the road surface μ, it is possible to realize the deceleration control without causing the driver to feel a sense of restraint. Thus, while performing deceleration control within the curve in accordance with the driver's intention, it is possible to realize deceleration control that does not give the driver a sense of restraint at the curve exit.

In the description of the above-described embodiment, the lateral acceleration limit value correction unit 17 controls the amount of deceleration control to decrease the amount of deceleration control when the curve exit detection unit detects that the vehicle is traveling on the curve exit. It constitutes a reduction means. Further, the lateral acceleration limit value correcting unit 17 constitutes a target lateral acceleration correction unit that corrects a lateral acceleration limit value Yg ^* that is a predetermined target lateral acceleration based on a driving operation or vehicle behavior by the driver.

1 shows a configuration of a vehicle that is an embodiment of the present invention and is equipped with a deceleration control device. It is a block diagram which shows the structure of the control controller which implement | achieves the said deceleration control apparatus. It is a flowchart which shows the basic process sequence of the said controller. It is a block diagram which shows the structure of the yaw rate calculation part of the said controller. It is a block diagram which shows the structure of the target vehicle speed calculation part of the said controller. It is a flowchart which shows the process sequence of the deceleration control part of the said controller. It is a flowchart which shows the process sequence of the curve exit determination part of the said controller. It is a flowchart which shows the process sequence of the lateral acceleration limit value correction | amendment part of the said controller. It is a flowchart which shows the other process sequence by the said curve exit determination part. It is a characteristic diagram of a second lateral acceleration limit value correction amount Ygb. It is a characteristic diagram of the third lateral acceleration limit value correction amount Ygc. It is a characteristic diagram of a fourth lateral acceleration limit value correction amount YGD. It is a flowchart which shows the process sequence of the correction | amendment of the target vehicle speed performed considering that the road surface μ is an estimated value.

Explanation of symbols

2 Control Controller 3 Engine Throttle Control Unit 4 Brake Control Unit 5 Yaw Rate Sensor 6 Wheel Speed Sensor 7 Steering Angle Sensor 11 Yaw Rate Calculation Unit 12 Lateral Acceleration Limit Value Calculation Unit 13 Target Vehicle Speed Calculation Unit 14 Target Deceleration Calculation Unit 15 Deceleration Control Unit 16 Curve exit determination unit 17 Lateral acceleration limit value correction unit

Claims (3)

In a deceleration control device that performs deceleration control to achieve a target vehicle speed set based on a turning state when the vehicle is turning,
An estimated yaw rate calculating means for calculating an estimated yaw rate of the vehicle based on the steering angle and the actual vehicle speed;
An actual yaw rate detecting means for detecting an actual yaw rate generated in the vehicle;
Based on a value obtained by dividing the limit value of the lateral acceleration at which the vehicle can turn stably by dividing by the larger value of the estimated yaw rate calculated by the estimated yaw rate calculating means and the actual yaw rate detected by the actual yaw rate detecting means. Target vehicle speed setting means for setting the target vehicle speed,
Curve exit detection means for detecting that the vehicle is traveling on the curve exit;
When the curve exit detection means detects that the vehicle is traveling on the curve exit, the throttle opening corresponding lateral acceleration limit value correction amount that increases as the throttle opening increases, and decreases as the vehicle speed increases. Correcting means for correcting the lateral acceleration limit value correction amount corresponding to the vehicle speed to be added to the limit value of the lateral acceleration;
A deceleration control device comprising: In a deceleration control device that performs deceleration control to achieve a target vehicle speed set based on a turning state when the vehicle is turning,
When the vehicle behavior changes in the direction in which the actual yaw rate increases from the estimated yaw rate according to the steering wheel operation position when traveling on a low μ road surface, the limit value of the lateral acceleration at which the vehicle can stably turn is divided by the actual yaw rate. Target vehicle speed setting means for setting the target vehicle speed based on a value ;
Curve exit detection means for detecting that the vehicle is traveling on the curve exit;
When the curve exit detection means detects that the vehicle is traveling on the curve exit, the throttle opening corresponding lateral acceleration limit value correction amount that increases as the throttle opening increases, and decreases as the vehicle speed increases. Correcting means for correcting the lateral acceleration limit value correction amount corresponding to the vehicle speed to be added to the limit value of the lateral acceleration;
Deceleration control apparatus comprising: a. 3. The correction according to claim 1, wherein the correction unit performs correction by adding a lateral acceleration limit value correction amount corresponding to an uphill gradient that increases in accordance with an increase in an uphill gradient of the traveling road to the limit value of the lateral acceleration. The deceleration control device described.

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