Vehicle traveling control device

Abstract

A control device detects a first vehicle traveling in front of an own vehicle using a front looking radar device, and detects a second vehicle which is predicted to cut in between the own vehicle and the first vehicle using the front looking radar device and/or front-side looking radar devices. The control device calculates a first target acceleration required for the own vehicle to maintain an inter-vehicle distance between the own vehicle and the first vehicle at a first set inter-vehicle distance; and calculates a second target acceleration required for the own vehicle to maintain an inter-vehicle distance between the own vehicle and the second vehicle at a second set inter-vehicle distance. The control device selects either the first target acceleration or the second target acceleration and controls the own vehicle in such a manner that an actual acceleration of the own vehicle becomes closer to the mediated target acceleration.

Description

G1tgt(for deceleration)=Kd1·(K1·ΔD1+K2·Vfx(a))  (2)

The target acceleration G1tgt for deceleration calculated based on the formula (2) above is calculated in such a manner that the target acceleration G1tgt is allowed to be an acceleration (negative acceleration) realized/achieved when the brake device of the own vehicle VA is operated (in other words, the target acceleration G1tgt may be a value obtained under a condition that it is allowed to be a negative acceleration realized/achieved when the brake device is operated). In the above manner, the target acceleration G1tgt for trailing travel based solely/only on the front looking radar obtained information is acquired.

2. Calculation of the Target Acceleration for Cut-in Vehicle

Further, at an appropriate point in time, the CPU starts processing from step 400 in a “routine for calculation of the target acceleration for cut-in vehicle” shown in FIG. 4 to proceed to step 405. At step 405, the CPU transforms coordinates concerning the position of the target object and the relative speed, obtained by the front-side looking radar device 22L and the front-side looking radar device 22R (that is, the front-left-side looking radar obtained information, and the front-right-side looking radar obtained information) to the “X-Y coordinates of the front looking radar device 21.” Consequently, the “coordinate transformed front-side looking radar information FSXn”, including an inter-vehicle distance Dsx, a relative speed Vsx, a lateral distance Dsy, and a relative lateral speed Vsy, is obtained.

Subsequently, the CPU proceeds to step 410 to compare the front looking radar obtained information FRXn with/to the coordinate transformed front-side looking radar information FSXn in order to determine whether or not there is a “target object which at least one of the front-side looking radar device 22L and the front-side looking radar device 22R detects” among the target objects which the front looking radar device 21 detects and which are different from (other than) the objective-forward-vehicle (a).

When the determination at step 410 is positive (affirmative), the CPU proceeds to step 415 at which the CPU integrates/merges the target object information according to a formula (3) described below. That is, at step 415, the CPU obtains integrated target object information. α(t) in the formula (3) described below is a filtering coefficient (weighting coefficient), and is obtained by applying a time t to a look up table Mapα(t) shown in a block B1 in FIG. 4. The time t is an elapsed time from a point in time at which the front looking radar device 21 starts to detect the “target object” which either one of the front-side looking radar device 22L and the front-side looking radar device 22R has been detecting. According to the table Mapα(t), α(t) is obtained as a value which gradually becomes closer to “1” from a value α0 between “0” and “1” as the elapsed time t becomes longer. It should be noted that α(t) may be a constant value between “0” and “1”, which does not change depending upon the elapsed time t.
Integrated value=α(t)·FRXn+(1−α(t))·FSXn  (3)

The front looking radar obtained information FRXn in the formula (3) above includes “an inter-vehicle distance Dfx (b), a relative speed Vfx(b), a lateral distance Dfy(b), and a relative lateral speed Vfy(b)” concerning the “target object (hereinafter, referred to as a “common target object (b)”) which was determined at step 410 to be detected by not only the front looking radar device 21 but also either one of the front-side looking radar device 22L and the front-side looking radar device 22R. The coordinate transformed front-side looking radar information FSXn in the formula (3) above includes “a coordinate transformed inter-vehicle distance Dsx, a coordinate transformed relative speed Vsx, a coordinate transformed lateral distance Dsy, and a coordinate transformed relative lateral speed Vsy” concerning the common target object (b). Accordingly, as shown in formulas from (4) to (7) described below, “an integrated inter-vehicle distance Dmx, an integrated relative speed Vmx, an integrated lateral distance Dmy, and an integrated relative lateral speed Vmy” serving as the integrated values are obtained.
Dmx=α(t)·Dfx(b)+(1−α(t))−Dsx  (4)
Vmx=α(t)·Vfx(b)+(1−α(t))·Vsx  (5)
Dmy=α(t)·Dfy(b)+(1−α(t))·Dsy  (6)
Vmy=α(t)−Vfy(b)+(1−α(t))·Vsy   (7)

Subsequently, the CPU proceeds to step 420 to determine whether or not the there is a predicted cut-in vehicle (i.e., whether or not a vehicle which is predicted to cut in exists). More specifically, the CPU obtains a cut-in event probability P by applying “the integrated lateral distance Dmy and the integrated relative speed Vmy” to an area map WS shown in FIG. 5.

For example, when a vehicle traveling in front and diagonally to the left of the own vehicle VA cuts in between the own vehicle VA and the objective-forward-vehicle (a), a trajectory (locus) of a point defined by the integrated lateral distance Dmy and the integrated relative lateral speed Vmy changes as shown by a broken line TL in FIG. 5. The area map WS is made in consideration of such trajectories, and is stored in the ROM beforehand. Generally speaking, the cut-in event probability P obtained using the area map WS becomes higher as an magnitude of the integrated lateral distance Dmy becomes closer to “0”, and becomes higher as a magnitude |Vmy| of the integrated relative lateral speed Vmy becomes larger when the integrated relative lateral speed Vmy is a value indicating that the vehicle is approaching the center portion of the width of the own vehicle.

The CPU determines that there is the “predicted cut-in vehicle”, when the CPU determines that the cut-in event probability P obtained using the area map WS is equal to or higher than a predetermined value (e.g., 60%). That is, the CPU specifies that target object as the predicted cut-in vehicle.

When it is determined that there is the predicted cut-in vehicle, the CPU makes a “Yes” determination at step 420 to execute processes of step 430 and step 435 described below in this order, and then, proceeds to step 495 so as to end the present routine tentatively.

Step 430: The CPU calculates an inter-vehicle deviation (difference) ΔD2 by subtracting the target inter-vehicle distance Dtgt from the integrated inter-vehicle distance Dmx. It should be noted that the target inter-vehicle distance Dtgt used at step 430 is referred to as a “second set inter-vehicle distance”, as a matter of convenience. The second set inter-vehicle distance may be the same as the first set inter-vehicle distance, or may be a value which becomes closer to the first set inter-vehicle distance from a value smaller than the first set inter-vehicle distance by a positive first value as an “elapsed time t from a point in time at which it was determined that there was the predicted cut-in vehicle” becomes longer. In this case, the target inter-vehicle time for calculating the second set inter-vehicle distance may be a time obtained by multiplying the “target inter-vehicle time Ttgt used when the first set inter-vehicle distance is calculated” by a “coefficient s(t)” which comes closer to and converges on “1” from a value between “0” and “1” as the above mentioned time t becomes longer.

Step 435: The CPU calculates the target acceleration G2tgt for cut-in vehicle according to either one of a formula (8) and a formula (9) described below. The target acceleration G2tgt for cut-in vehicle is referred to as a “second target acceleration”, as a matter of convenience. Further, the CPU sets a target acceleration G3tgt for cut-in vehicle described later at an “imaginary acceleration G3infinite” which is larger than a maximum acceleration that the own vehicle VA can realize.

In the formula (8) and the formula (9), Vmx is the integrated relative speed of the target object which was determined to be the predicted cut-in vehicle at step 420, and “K1, and K2” are the same gains as the “K1, and K2” used in the formula (1) and the formula (2), respectively. The CPU uses the formula (8) below when a value (K1·ΔD2+K2·Vmx) is positive.

Ka2 is a positive gain (coefficient) for acceleration, and set at a value smaller than the gain Ka1 used in the formula (1) above.

The CPU uses the formula (9) below when the value (K1·ΔD2+K2·Vmx) is negative.

Kd2 is a positive gain (coefficient) for deceleration, and set at a value smaller than the gain Kd1 used in the formula (2) above.
G2tgt(for acceleration)=Ka2·(K1·ΔD2+K2·Vmx)  (8)
G2tgt(for deceleration)=Kd2·(K1·ΔD2+K2·Vmx)  (9)

The target acceleration G2tgt for cut-in vehicle for deceleration calculated based on the formula (9) above is calculated in such a manner that the target acceleration G2tgt is allowed to be an acceleration (negative acceleration) realized/achieved when the brake device of the own vehicle VA is operated, similarly to the target acceleration G1tgt for trailing travel. In other words, the target acceleration G2tgt for cut-in vehicle may become a value obtained under the condition that it is allowed to be a negative acceleration realized/achieved when the brake device is operated. In the above manner, the target acceleration G2tgt for cut-in vehicle is calculated based on the integrated/merged information (integrated values) obtained by integrating the front looking radar obtained information and the coordinate transformed front-side looking radar information.

In contrast, when the CPU determines that there is no predicted cut-in vehicle upon the execution of step 420, the CPU makes a “No” determination at step 420 to proceed to step 425, at which the CPU sets the target acceleration G2tgt for cut-in vehicle at an “imaginary acceleration G2infinite” which is larger than the maximum acceleration that the own vehicle VA can realize, and sets the target acceleration G3tgt for cut-in vehicle described later at the “imaginary acceleration G3infinite” which is larger than the maximum acceleration that the own vehicle VA can realize. Thereafter, the CPU proceeds to step 495 to end the present routine tentatively.

On the other hand, when the determination at step 410 is negative (unaffirmative), the CPU makes a “No” determination. Then, the CPU proceeds to step 440, at which the CPU determines whether or not there is a predicted cut-in vehicle. In this case, the CPU obtains the cut-in event probability P by applying “the coordinate transformed lateral distance Dsy in place of the integrated lateral distance Dmy, and the coordinate transformed relative lateral speed Vsy in place of the integrated relative speed Vmy” to the area map WS shown in FIG. 5. Thereafter, the CPU determines that there is the “predicted cut-in vehicle”, when the cut-in event probability P is equal to or larger than the predetermined value (e.g., 60%), similarly to step 420. That is, the CPU specifies that target object as the predicted cut-in vehicle.

When it is determined that there is the predicted cut-in vehicle, the CPU makes a “Yes” determination at step 440 to proceed to step 450, at which the CPU determines whether or not a lane change (changing lanes) of the predicted cut-in vehicle occurs in front of the own vehicle VA.

For example, as shown in (A) of FIG. 6, when the vehicle VC is cutting in while the own vehicle VA is following the objective-forward-vehicle VB, it is determined that the vehicle VC is the predicted cut-in vehicle. In this case, if the speed Vj of the own vehicle VA is 80 km/h, and the speed of the predicted cut-in vehicle VC is 85 km/h, it is likely that the predicted cut-in vehicle VC will cut in between the own vehicle VA and the objective-forward-vehicle VB.

In contrast, as shown in (B) of FIG. 6, when the own vehicle VA is following (i.e., trailing) the objective-forward-vehicle VB at 80 km/h, and the speed of the predicted cut-in vehicle VC is 60 km/h, it is likely that the predicted cut-in vehicle VC will change lanes to travel behind the own vehicle VA, after the own vehicle VA passes the predicted cut-in vehicle VC.

Step 450 is for determining which situation is occurring, the situation shown in (A) of FIG. 6, or the situation shown in (B) of FIG. 6. More specifically, the CPU determines whether or not the coordinate transformed relative speed Vsx is equal to or higher than a predetermined threshold Vth so as to determine whether or not the changing lanes of the predicted cut-in vehicle occurs in front of the own vehicle VA. It should be noted the predetermined threshold Vth may be set at a value larger than a negative certain value.

When it is determined that the changing lanes of the predicted cut-in vehicle occurs in front of the own vehicle VA (i.e., when it is determined that the coordinate transformed relative speed Vsx is equal to or higher than the predetermined threshold Vth), the CPU makes a “Yes” determination at step 450 to execute processes of step 455 and step 460 described below in this order, and then, proceeds to step 495 so as to end the present routine tentatively.

Step 455: The CPU calculates an inter-vehicle deviation (difference) ΔD3 by subtracting the target inter-vehicle distance Dtgt from the coordinate transformed inter-vehicle distance Dsx. It should be noted that the target inter-vehicle distance Dtgt used at step 455 is referred to as a “third set inter-vehicle distance”, as a matter of convenience. The third set inter-vehicle distance may be the same as the second set inter-vehicle distance, or may be a value which becomes closer to the first set inter-vehicle distance from a value smaller than the second set inter-vehicle distance by a positive first value as the “elapsed time t from the point in time at which it was determined that there was the predicted cut-in vehicle” becomes longer. In this case, the target inter-vehicle time for calculating the third set inter-vehicle distance may be a time obtained by multiplying the “target inter-vehicle time Ttgt used when the first set inter-vehicle distance is calculated” by a “coefficient u(t)” which comes closer to and converges on “1” from a value between “0” and “1” and smaller than the coefficient s(t)=s(0) as the above mentioned time t becomes longer. It should be noted that the coefficient u(t) is adjusted so as to be equal to or smaller than the coefficient s(t).

Step 460: The CPU calculates the target acceleration G3tgt for cut-in vehicle according to either one of a formula (10) and a formula (11) described below. The target acceleration G3tgt for cut-in vehicle is referred to as a “third target acceleration”, as a matter of convenience. Further, the o CPU sets the target acceleration G2tgt for cut-in vehicle at the “imaginary acceleration G2infinite” which is larger than the maximum acceleration that the own vehicle VA can realize.

In the formula (10) and the formula (11), Vsx is the coordinate transformed relative speed of the target object which was determined to be the predicted cut-in vehicle at step 440, and “K1, and K2” are the same gains as the “K1, and K2” used in the formula (1) and the formula (2), respectively. The CPU uses the formula (10) below when a value (K1·ΔD3+K2·Vsx) is positive.

Ka3 is a positive gain (coefficient) for acceleration, and set at a value smaller than (or equal to) the gain Ka2 used in the formula (8) above.

The CPU uses the formula (1) below when the value (K1·ΔD3+K2·Vsx) is negative.

Kd3 is a positive gain (coefficient) for deceleration, and set at a value smaller than (or equal to) the gain Kd2 used in the formula (9) above.
G3tgt(for acceleration)=Ka3·(K1·ΔD3+K2·Vsx)  (10)
G3tgt(for deceleration)=Kd3·(K1·ΔD3+K2·Vsx)  (11)

Note that G3tgt is limited so as to be larger than an acceleration (G@TA=0) obtained when the throttle valve opening TA is equal to 0 (G3tgt≤G@TA=0).

The target acceleration G3tgt for cut-in vehicle for deceleration calculated based on the formula (11) above is limited so as not to be equal to or smaller than an acceleration (negative acceleration) G@TA=0 realized/achieved when the throttle valve opening of the internal combustion engine is “0 (or the minimum value within a range that the throttle valve opening can become)” (namely, the throttle valve is fully-closed) while the brake device of the own vehicle VA is not operated. That is, a process for limiting with a lower limit that is the throttle valve fully closed acceleration G@TA=0 on the target acceleration G3tgt for cut-in vehicle is performed. The throttle valve fully closed acceleration G@TA=0 may be said to be a minimum acceleration which the own vehicle VA can realize/achieve without operating the brake device of the own vehicle VA.

More specifically, at step 460, the CPU calculates the target acceleration G3tgt for cut-in vehicle according to either the above formula (10) or the above formula (11). The CPU sets the thus calculated target acceleration G3tgt for cut-in vehicle at the throttle valve fully closed acceleration G@TA=0 if the thus calculated target acceleration G3tgt is smaller than the throttle valve fully closed acceleration G@TA=0. It should be noted that the CPU separately calculates the throttle valve fully closed acceleration G@TA=0 based on the engine rotational speed NE and a gear position of an unillustrated transmission of the own vehicle VA on the assumption that the CPU operates the internal combustion engine under the fuel cut state when the throttle valve opening is “0.” In this manner, the target acceleration G3tgt for cut-in vehicle is obtained based solely/only on the (coordinate transformed) front-side looking radar information.

In contrast, when the CPU makes a “No” determination at either step 440 or step 450, the CPU proceeds to step 445. The CPU sets the target acceleration G2tgt for cut-in vehicle at the “imaginary acceleration G2infinite” which is larger than the maximum acceleration that the own vehicle VA can realize, and sets the target acceleration G3tgt for cut-in vehicle at the “imaginary acceleration G3infinite” which is larger than the maximum acceleration that the own vehicle VA can realize. Thereafter, the CPU proceeds to step 495 to end the present routine tentatively.

3. Mediation/Adjustment of Target Acceleration and Vehicle Travel Control

At an appropriate point in time, the CPU starts processing from step 700 of a “routine for mediation of target acceleration and vehicle travel control” shown in FIG. 7, to execute processes of step 710 and step 720 in this order, and proceeds to step 795 to end the present routine tentatively.

Step 710: The CPU selects one of the target acceleration G1tgt for trailing travel, the target acceleration G2tgt for cut-in vehicle, and the target acceleration G3tgt for cut-in vehicle, whichever is smallest, and sets the selected target acceleration as the “final target acceleration (mediated/adjusted target acceleration) Gfin.” That is, the CPU mediates among three kinds of target accelerations. In other words, when the target acceleration G2tgt for cut-in vehicle, and the target acceleration G3tgt for cut-in vehicle are considered to be a single target acceleration for cut-in vehicle, the CPU selects either the target acceleration for trailing travel or the target acceleration for cut-in vehicle, whichever is smaller, as the mediated target acceleration Gfin.

Step 720: The CPU sends the mediated target acceleration Gfin to the engine ECU 30 and the brake ECU 40 in order to make the acceleration of the own vehicle VA become equal to the mediated target acceleration Gfin. The engine ECU 30 and the brake ECU 40 control (drive) the engine actuators 32 and the brake actuators 42, respectively, based on the mediated target acceleration Gfin. As a result, the actual acceleration of the own vehicle VA is made to become equal to the mediated target acceleration Gfin. In this manner, the trailing inter-vehicle distance control is performed.

As described above, the first device calculates the target acceleration G1tgt for trailing travel, the target acceleration G2tgt for cut-in vehicle, and the target acceleration G3tgt for cut-in vehicle, and sets the minimum (the smallest) target acceleration among them, as the “final target acceleration (mediated/adjusted target acceleration) Gfin.”

Accordingly, when the target acceleration (one of G2tgt and G3tgt) for cut-in vehicle is selected as the mediated target acceleration Gfin in a case where the predicted cut-in vehicle is detected, the own vehicle VA decelerates so as to increase the inter-vehicle distance between the own vehicle VA and the objective-forward-vehicle. Thus, when the predicted cut-in vehicle actually cuts in, the inter-vehicle distance with respect to the cut-in vehicle (i.e., distance between the own vehicle VA and the predicted cut-in vehicle that is now an actual cut-in vehicle) becomes appropriate in a short time. In addition, if the objective-forward-vehicle starts to rapidly decelerate after a point in time at which the predicted cut-in vehicle is detected, it is likely that the target acceleration G1tgt for trailing travel is selected as the mediated target acceleration Gfin. Therefore, in this case, the own vehicle VA decelerates so as to ensure/acquire an appropriate inter-vehicle distance with respect to the objective-forward-vehicle (i.e., appropriate inter-vehicle distance between the own vehicle VA and the objective-forward-vehicle). As a result, the inter-vehicle distance between the own vehicle VA and the objective-forward-vehicle becoming excessively short can be avoided, in a case where the predicted cut-in vehicle does not actually cut in.

In addition, when the front looking radar device 21 and the front-side looking radar device (22L, 22R) detect the same (identical) target object, the first device integrates/merges the target object information (first target object information) that the front looking radar device 21 obtains and the target object information (second target object information) that the front-side looking radar device (22L, 22R) obtains so as to obtain the integrated target object information. Thereafter, the first device determines the presence or absence of the predicted cut-in vehicle based on the integrated target object information, and further, calculates the target acceleration (G2tgt) for cut-in vehicle regarding (for) the predicted cut-in vehicle when the predicted cut-in vehicle is determined to exist. The target acceleration (G2tgt) for cut-in vehicle may be set at a value obtained on the assumption that the brake device is operated. In other words, the target acceleration (G2tgt) for cut-in vehicle is allowed to become a “negative acceleration whose absolute value is large (i.e., large deceleration)”.

On the other hand, when the predicted cut-in vehicle is detected based solely/only on the “second target object information obtained by the front-side looking radar device”, the first device obtains the target acceleration (G3tgt) for cut-in vehicle while providing the limitation on the target acceleration (G3tgt) for cut-in vehicle in such a manner that the target acceleration (G3tgt) for cut-in vehicle does not become smaller than the “negative acceleration realized/achieved when the throttle valve opening of the internal combustion engine of the own vehicle VA is “0 (or, the throttle valve is fully-closed)” while the brake device of the own vehicle VA is not operated”. Accordingly, when the cutting-in does not actually occur, the strong deceleration of the own vehicle VA due to the predicted cut-in vehicle does not occur. Thus, the driver avoids the odd feeling of rapid deceleration.

Second Embodiment

A vehicle travelling control device according to the second embodiment of the present disclosure (hereinafter, referred to as a “second device”) will next be described. The second device is different from the first device only in the following points.

(1) The second device neither comprises the front-side looking radar device 22L nor the front-side looking radar device 22R.

(2) The second device executes a routine shown in FIG. 8 in place of the routines shown in FIGS. 3 and 4, and executes a routine shown in FIG. 9 in place of FIG. 7.

Those different points will next be mainly described.

The CPU of the second device executes the “target acceleration calculation routine” shown in FIG. 8, every elapse of a predetermined time. It should be noted that the reference number given to the step shown in FIG. 3 is given to a step shown in FIG. 8 whose process is the same as the process of step shown in FIG. 3. The detailed description about such a step will be omitted.

At an appropriate point in time, the CPU starts processing from step 800 shown in FIG. 8 to execute the processes from step 310 to step 340 in this order. Consequently, the target acceleration G1tgt for trailing travel is calculated.

Subsequently, the CPU proceeds to step 810 to determine if there is a predicted cut-in vehicle. In this case, the CPU applies the lateral distance Dfy(n) and the lateral relative speed Vfy(n) of each of “target objects other than the target object which is determined to be the objective-forward-vehicle (a) at step 310, among the target objects (n) that the front looking radar device 21 detects” to the area map WS shown in FIG. 5, so as to obtain the cut-in event probability P of each of the target objects. The CPU determines that there is a predicted cut-in vehicle when there is a target object whose cut-in event probability P is equal to or higher than the predetermined value (e.g., 60%), similarly to step 420. That is, the CPU specifies that target object as the predicted cut-in vehicle.

When it is determined that there is the predicted cut-in vehicle, the CPU makes a “Yes” determination at step 810 to execute processes of step 820 and step 830 described below in this order, and then, proceeds to step 895 so as to end the present routine tentatively.

Step 820: The CPU calculates an inter-vehicle deviation (difference) ΔD4 by subtracting the target inter-vehicle distance Dtgt from the inter-vehicle distance Dfx(b). The inter-vehicle distance Dfx(b) is the inter-vehicle distance Dfx(n) of the target object (b) which is determined to be the predicted cut-in vehicle at step 810. It should be noted that the target inter-vehicle distance Dtgt used at step 820 is referred to as a “fourth set inter-vehicle distance”, as a matter of convenience. The fourth set inter-vehicle distance may be the same as the first set inter-vehicle distance, or may be a value which becomes closer to the first set inter-vehicle distance from a value smaller than the first set inter-vehicle distance by a positive first value as an “elapsed time t from a point in time at which it was determined that there was the predicted cut-in vehicle” becomes longer. In this case, the target inter-vehicle time for calculating the fourth set inter-vehicle distance may be a time obtained by multiplying the “target inter-vehicle time Ttgt used when the first set inter-vehicle distance is calculated” by the “coefficient s(t)” which comes closer to and converges on “1” from a value between “0” and “1” as the above mentioned time t becomes longer.

Step 830: The CPU calculates the target acceleration G4tgt for cut-in vehicle according to either one of a formula (12) and a formula (13) described below. The target acceleration G4tgt for cut-in vehicle is referred to as a “fourth target acceleration”, as a matter of convenience.

In the formula (12) and the formula (13), Vfx(b) is the relative speed Vfx(n) of the target object (b) which was determined to be the predicted cut-in vehicle at step 810, and “K1, and K2” are the same gains as the “K1, and K2” used in the formula (1) and the formula (2), respectively. The CPU uses the formula (12) below when a value (K1·ΔD4+K2·Vfx(b)) is positive.

Ka4 is a positive gain (coefficient) for acceleration, and is set at a value which is equal to or smaller than the gain Ka1 used in the above formula (1) (or than the gain Kat used at step 340 shown in FIG. 8).

The CPU uses the formula (13) below when the value (K1·ΔD4+K2·Vfx(b)) is negative.

Kd4 is a positive gain (coefficient) for deceleration, and is set at a value which is equal to or smaller than the gain Kd1 used in the above formula (2) (or than the gain Kd1 used at step 340 shown in FIG. 8).
G4tgt(for acceleration)=Ka4·(K1·ΔD4+K2·Vfx(b))·  (12)
G4tgt(for deceleration)=Kd4·(K1·ΔD4+K2·Vfx(b))  (13)

The target acceleration G4tgt for cut-in vehicle for deceleration calculated based on the formula (13) above is calculated in such a manner that the target acceleration G4tgt is allowed to be an acceleration (negative acceleration) realized/achieved when the brake device of the own vehicle VA is operated, similarly to the target acceleration G1tgt for trailing travel. In the above manner, the target acceleration G4tgt for cut-in vehicle is calculated based solely/only on the front looking radar obtained information.

In contrast, when the CPU determines that there is no predicted cut-in vehicle upon the execution of step 810, the CPU makes a “No” determination at step 810 to proceed to step 840, at which the CPU sets the target acceleration G4tgt for cut-in vehicle at the “imaginary acceleration G4infinite” which is larger than the maximum acceleration that the own vehicle VA can realize. Thereafter, the CPU proceeds to step 895 to end the present routine tentatively.

Further, at an appropriate point in time, the CPU starts processing from step 900 a “routine for mediation of target acceleration and vehicle travel control” shown in FIG. 9, to execute processes of step 910 and step 920 in this order, and proceeds to step 995 to end the present routine tentatively.

Step 910: The CPU selects either one of the target acceleration G1tgt for trailing travel and the target acceleration G4tgt for cut-in vehicle, whichever is smaller, and sets the selected target acceleration as the “final target acceleration (mediated/adjusted target acceleration) Gfin.” That is, the CPU mediates among two kinds of target accelerations.

Step 920: The CPU sends the mediated target acceleration Gfin to the engine ECU 30 and the brake ECU 40 in order to make the acceleration of the own vehicle VA become equal to the mediated target acceleration Gfin. The engine ECU 30 and the brake ECU 40 control (drive) the engine actuators 32 and the brake actuators 42, respectively, based on the mediated target acceleration Gfin. As a result, the actual acceleration of the own vehicle VA is made to become equal to the mediated target acceleration Gfin. In this manner, the trailing inter-vehicle distance control is performed.

As described above, the second device calculates the target acceleration G1tgt for trailing travel, and the target acceleration G4tgt for cut-in vehicle, and sets the smaller target acceleration among them as the “final target acceleration (mediated/adjusted target acceleration) Gfin.”

Accordingly, similarly to the first device, when the target acceleration G4tgt for cut-in vehicle is selected as the mediated target acceleration Gfin in a case where the predicted cut-in vehicle is detected, the own vehicle VA decelerates so as to increase the inter-vehicle distance between the own vehicle VA and the objective-forward-vehicle. Thus, when the predicted cut-in vehicle actually cuts in, the inter-vehicle distance with respect to the cut-in vehicle (i.e., distance between the own vehicle VA and the predicted cut-in vehicle that is now an actual cut-in vehicle) becomes appropriate in a short time. In addition, if the objective-forward-vehicle starts to rapidly decelerate after a point in time at which the predicted cut-in vehicle is detected, it is likely that the target acceleration G1tgt for trailing travel is selected as the mediated target acceleration Gfin. Therefore, in this case, the own vehicle VA decelerates so as to ensure/acquire an appropriate inter-vehicle distance with respect to the objective-forward-vehicle (i.e., appropriate inter-vehicle distance between the own vehicle VA and the objective-forward-vehicle). As a result, the inter-vehicle distance between the own vehicle VA and the objective-forward-vehicle becoming excessively short can be avoided, in a case where the predicted cut-in vehicle does not actually cut in.

The present disclosure is not limited to the embodiments described above, and various modifications may be adopted within the scope of the present disclosure. For example, as shown in FIGS. 1 and 2, each of the first device and the second device may comprise a stereo camera 101 which can communicate with the driving support ECU through the CAN 100. The stereo camera 101 is positioned at an upper portion of a front window within a passenger room, and acquires a stereo image in a straight forward direction of the own vehicle VA. From the stereo image, the stereo camera 101 obtains the target object information, and lane markers (white lines). The stereo camera 101 can recognize the running lane based on the lane markers, and the like. In this case, the first device and the second device may obtain the objective-forward-vehicle and the predicted cut-in vehicle from the target object information that the front looking radar device 21 and the stereo camera 101 acquire. Further, the first device and the second device may estimate a course of the own vehicle VA based on the information concerning the running lane obtained from the stereo camera 101, and may modify the target information which is obtained by the front looking radar device 21 and/or the front-side looking radar device 22L, 22R in consideration of the estimated course, for example, in such a manner that the lateral position of the target object become a target position in a direction orthogonal to the estimated course.

Further, the first device and the second device may be configured to determine whether or not there is a predicted cut-in vehicle using a map other than the map shown in FIG. 5. For example, the first device and the second device may be configured to determine whether or not there is a predicted cut-in vehicle in consideration of not only the lateral position and the lateral relative speed of the vehicles other than the objective-forward-vehicle but also the inter-vehicle distance of the vehicles.

Claims

1. A vehicle travelling control device comprising:

detecting means for detecting an objective-forward-vehicle traveling in front of an own vehicle and a vehicle which is predicted to cut in between said own vehicle and said objective-forward-vehicle;

first calculation means for calculating a first target acceleration for the own vehicle to maintain an inter-vehicle distance between said own vehicle and said objective-forward-vehicle at a first set inter-vehicle distance;

second calculation means for calculating a second target acceleration required for said own vehicle to maintain an inter-vehicle distance between said own vehicle and said predicted cut-in vehicle at a second set inter-vehicle distance;

mediation means for selecting, as a mediated target acceleration, either said first target acceleration or said second target acceleration, whichever is smaller; and

travel control means for controlling a driving force and a brake force of said own vehicle in such a manner that an actual acceleration of said own vehicle becomes closer to said mediated target acceleration,

wherein:

said detecting means includes

a front looking radar device having a front looking detection area, the front looking detection area having a center axis extending in a straight forward direction of said own vehicle, the front looking radar detects a target object to obtain first target object information concerning said target object, and

a front-side looking radar device having a front-side detection area, the front-side detection area having a center axis extending in a diagonally forward direction of said own vehicle, the front-side looking radar detects said target object to obtain second target object information concerning said target object;

said vehicle travelling control device further comprises predicted cut-in vehicle detecting means for

integrating said first target object information and said second target object information to obtain an integrated target object information, and detecting said predicted cut-in vehicle based on said integrated target object information, when said front looking radar device and said front-side looking radar device detect an identical target object, and

detecting said predicted cut-in vehicle based on said second target object information but not based on said first target object information, when said front-side looking radar device detects said target object, but said front looking radar device does not detect said target object and

said second calculation means

calculates said second first target acceleration in such a manner that said said second target acceleration is allowed to be a negative acceleration achieved when a brake device of said own vehicle is operated, in a case where said predicted cut-in vehicle is detected based on said integrated target object information, and

calculates said said second target acceleration while providing a limitation on said said second target acceleration in such a manner that said said second target acceleration does not become smaller than a negative acceleration achieved when a throttle valve opening of an internal combustion engine serving as a driving force of said own vehicle is set at a minimum value while said brake device of said own vehicle is not operated, in a case where said predicted cut-in vehicle is detected based on said second target object information but not based on said first target object information.

2. A vehicle travelling control device comprising:

a radar system that detects an objective-forward-vehicle traveling in front of an own vehicle and a vehicle which is predicted to cut in between said own vehicle and said objective-forward-vehicle;

an electronic control unit implemented by at least one processor programmed and configured to

calculate a first target acceleration for the own vehicle to maintain an inter-vehicle distance between said own vehicle and said objective-forward-vehicle at a first set inter-vehicle distance,

calculate a second target acceleration required for said own vehicle to maintain an inter-vehicle distance between said own vehicle and said predicted cut-in vehicle at a second set inter-vehicle distance, and

select, as a mediated target acceleration, either said first target acceleration or said second target acceleration, whichever is smaller;

an engine electronic control unit; and

a brake electronic control unit;

wherein the engine electronic control unit and the brake electronic control unit control a driving force and a brake force, respectively, of said own vehicle in such a manner that an actual acceleration of said own vehicle becomes closer to said mediated target acceleration,

wherein said radar system includes

a front looking radar device having a front looking detection area, the front looking detection area having a center axis extending in a straight forward direction of said own vehicle, the front looking radar detects a target object to obtain first target object information concerning said target object, and

a front-side looking radar device having a front-side detection area, the front-side detection area having a center axis extending in a diagonally forward direction of said own vehicle, the front-side looking radar detects said target object to obtain second target object information concerning said target object, and

wherein said electronic control unit is further configured to

integrate said first target object information and said second target object information to obtain an integrated target object information, and detect said predicted cut-in vehicle based on said integrated target object information, when said front looking radar device and said front-side looking radar device detect an identical target object,

detect said predicted cut-in vehicle based on said second target object information but not based on said first target object information, when said front-side looking radar device detects said target object, but said front looking radar device does not detect said target object,

calculate said first second target acceleration in such a manner that said first second target acceleration is allowed to be a negative acceleration achieved when a brake device of said own vehicle is operated, in a case where said predicted cut-in vehicle is detected based on said integrated target object information, and

calculate said first second target acceleration while providing a limitation on said first second target acceleration in such a manner that said first second target acceleration does not become smaller than a negative acceleration achieved when a throttle valve opening of an internal combustion engine serving as a driving force of said own vehicle is set at a minimum value while said brake device of said own vehicle is not operated, in a case where said predicted cut-in vehicle is detected based on said second target object information but not based on said first target object information.