JPH08192659A - Running control device of vehicle - Google Patents

Abstract

PURPOSE: To control deceleration without making worse a driving feeling and a follow-up property to the preceding vehicle by releasing deceleration control by gear shifting, when deceleration control by braking is begun during a prescribed time after beginning of deceleration control by gear shifting. CONSTITUTION: The inter-vehicle distance to the preceding vehicle is measured by an inter-vehicle distance measuring means 12, and when the inter-vehicle distance becomes small, a command is output to an automatic transmission 32 from a control state computing part 6 and a control content computing part 8, and hence deceleration control by gear shifting of the transmission to a low speed step side. When the inter-vehicle distance becomes further small, deceleration is controlled by braking of wheels by commanding to a brake actuator 34. When the deceleration control by braking of the wheels is begun during a prescribed time after beginning of deceleration control by gear shifting to the low speed step side, the control by gear shifting is released. Hereby deceleration control becomes possible without making worse a driving feeling and a follow-up property to the preceding vehicle.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle travel control device, and more particularly to deceleration control during tracking travel.

[0002]

2. Description of the Related Art In order to reduce the driving operation of a vehicle, an inter-vehicle distance control device has been developed which controls the tracking of a preceding vehicle. For vehicles equipped with an inter-vehicle distance control device, when the set switch is pressed, the set inter-vehicle distance is calculated from the vehicle speed at that time, and the inter-vehicle distance measurement device (camera, radar, etc.) detects the inter-vehicle distance from the preceding vehicle. Then, the engine output and the brake are controlled so that the inter-vehicle distance to the preceding vehicle becomes the set inter-vehicle distance, so that the vehicle travels following the preceding vehicle.

In addition to engine braking for suppressing engine output, there are braking means for shifting gears to the low speed side and braking for wheels. These braking means are selected and used. An apparatus having the structure is disclosed in Japanese Patent Application Laid-Open No. 61-77534.

[0004]

By the way, in recent years, it has been considered to perform brake control by combining the above-mentioned braking means in accordance with the inter-vehicle distance. However, when shifting to a low speed stage of a transmission, especially an automatic transmission, a deceleration shock may occur and the vehicle may be in a state where it is momentarily braked. When such a deceleration shock occurs, driving feeling is deteriorated.

Further, when the braking operation is performed by combining other braking, particularly wheel braking, simultaneously with the shifting to the low speed stage of the transmission, the deceleration shock is increased and becomes even greater, and the driving feeling is further improved. It will get worse. Therefore, it is conceivable to prevent other braking, particularly wheel braking, from being performed for a certain period after the shift of the transmission to the low speed stage is started.

However, when such control is performed,
For a certain period of time, only braking by shifting the transmission is performed, and if the vehicle speed of the preceding vehicle becomes slow and the inter-vehicle distance suddenly decreases during this period, the vehicle speed of the preceding vehicle cannot be immediately followed. The present invention has been made based on the above-mentioned circumstances, and an object of the present invention is to provide a vehicle traveling control device capable of realizing deceleration control without deteriorating the driving feeling and the following ability to follow a preceding vehicle. Especially.

[0007]

In order to achieve the above-mentioned object, in the invention of claim 1, the inter-vehicle distance with the preceding vehicle is measured by the inter-vehicle distance measuring means, and the measured inter-vehicle distance is a predetermined distance. In a travel control device for a vehicle, which includes a tracking travel control means for controlling the vehicle speed so that the vehicle speed is reduced, the first deceleration is performed by decelerating the vehicle speed by shifting to a lower speed side of the transmission when the inter-vehicle distance decreases. Control means, second deceleration control means for decelerating the vehicle speed by braking the wheels together with the first deceleration control means when the inter-vehicle distance becomes smaller, and deceleration by the first deceleration control means. And a canceling unit for canceling the deceleration control by the first deceleration control unit when the deceleration control by the second deceleration control unit is started within a predetermined time after the control is started. It is characterized in.

Further, the invention of claim 2 is characterized in that the predetermined time period is a time period from when a shift command is supplied to the transmission until the shift is achieved.

[0009]

According to the vehicle running control device of the first aspect, the deceleration control by shifting to the lower speed stage of the transmission, which is performed when the inter-vehicle distance becomes shorter, is performed when the inter-vehicle distance becomes further smaller. When the deceleration control by braking the wheels, which is carried out at the same time as the gear shift to the low speed side of the transmission, is started within a predetermined time from the start of the deceleration control by the gear shift to the low speed side of the transmission, the releasing means Is released by. As a result, the vehicle travels satisfactorily by controlling the deceleration only by braking the wheels without deteriorating the driving feeling.

According to another aspect of the vehicle travel control device of the present invention, the predetermined time is the time from when the gear shift command is supplied to the transmission to when the gear shift is achieved. Therefore, until the gear shift is achieved. When the braking of the wheels is started during the period, the shift of the transmission to the low speed stage side is released, and the vehicle is decelerated only by braking the wheels. When the shift is achieved, the deceleration control that combines the shift to the low speed side of the transmission and the braking of the wheels becomes possible immediately.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a system configuration diagram of a traveling control device. Hereinafter, the configuration of the traveling control device will be described with reference to FIG. The travel control device is provided with a main control unit (ECU) 2 that controls travel control. On the input side of the ECU 2, a control power switch 11 for starting up the ECU 2, a CCD camera (not shown) provided in the front part of the vehicle, and a scanning type laser radar (not shown).
And the like, and an inter-vehicle distance measuring device 12 for confirming the preceding vehicle and measuring the current inter-vehicle distance DS between the preceding vehicle and the own vehicle, and a traveling lane recognition device 14 mainly comprising a CCD camera for confirming the traveling lane, A vehicle speed meter 16 for measuring the current vehicle speed VS, an operation switch for inputting a start / reset command for traveling control, a vehicle-to-vehicle time TC and a set vehicle speed Vm described later, and a return operation to the set vehicle speed Vm, that is, a resume operation. 18, a throttle sensor, a wheel speed sensor,
Various sensor switches 2 including a steering angle sensor and a warning switch (indicated by reference numeral 54 in FIG. 2) 2
0 is connected.

On the other hand, the output side of the ECU 2 is connected with a throttle actuator 30, an automatic transmission (A / T) 32, a brake actuator 34 for activating wheel brakes (not shown), and the like.
These are designed to operate based on an input signal from the input side. Further, an output side of the ECU 2 is connected to a display 40 that is provided on an instrument panel (reference numeral 50 in FIG. 2) in front of the driver's seat and displays a traveling control state, so that the driver can display the traveling control state. It can be easily confirmed.

The inside of the ECU 2 is divided into four processing units, that is, an input processing unit 4, a control state calculation unit 6, a control content calculation unit 8 and a display content calculation unit 10, as shown in FIG. Inter-vehicle distance measuring device 12, traveling lane recognition device 14,
An input signal supplied from the vehicle speedometer 16, the operation switch 18, and various sensor switches 20 is processed into an output signal by the control content calculation unit 8 or the display content calculation unit 10 via the input processing unit 4 and the control state calculation unit 6. Is output. The control content calculator 8 outputs drive signals to the throttle actuator 30, the A / T 32, and the brake actuator 34, and the display content calculator 10 outputs display signals to the display 40.

FIG. 2 schematically shows the vicinity of the instrument panel 50 in the driver's seat. As shown in the figure,
The instrument panel 50 is provided with the control power switch 11, the warning switch 54, the combination meter 60 having a function as the display 40, the center message display 41, and the like. The warning switch 54 is a switch for activating an inter-vehicle distance warning buzzer (not shown) that informs by a warning sound that the preceding vehicle approaches and the current inter-vehicle distance DS has become smaller.

The lever type operation switch 18 is provided on a steering wheel 56 extending from the lower portion of the instrument panel 50 toward the driver. The operation switch 18 can perform an increasing operation of a set vehicle speed Vm and a decreasing operation of an inter-vehicle time TC which will be described later by a raising operation, and an input (set) of a start command for traveling control and a setting vehicle speed Vm which will be described later by a lowering operation. It is possible to perform a decrease operation for the vehicle, an increase operation for the inter-vehicle time TC, and a resume operation. By operating the front side, a cancellation command for the traveling control can be input (cancelled).

The combination meter 60 has, as a display function, a traveling control operation indicating lamp 62 indicating whether or not traveling control is being carried out and a warning buzzer operating lamp 64 indicating whether or not an inter-vehicle distance warning buzzer is operating.
Is provided. Further, on the center message display 41, a set vehicle speed display section 42 for displaying the set vehicle speed Vm in a line drawing schematically showing the outline of the vehicle and a current vehicle between two arrows pointing in a direction away from each other are displayed. Distance between cars D
An inter-vehicle distance display unit 44 that displays S, a preceding vehicle display unit 46 that displays the presence or absence of a preceding vehicle with a line drawing that schematically shows the contour of the rear portion of the vehicle, and a warning lamp 48 are provided.
The set vehicle speed Vm displayed on the set vehicle speed display unit 42 is limited to the set range (for example, 40 to 105 km / h),
Further, the current inter-vehicle distance DS displayed on the inter-vehicle distance display section 44 is a predetermined distance D1 (eg, 99 m) which needs to be displayed.
Limited to

FIG. 3 is a flow chart showing a control routine of the traveling control executed by the ECU 2. Hereinafter, the control outline of the travel control device configured as described above will be described with reference to FIG. In step S10, the ignition O
After N, various internal values of the controller are initialized based on the system power being turned on. When step S10 ends, the processing of the main routine that is repeated at fixed control cycles ts (for example, 26 msec) is performed. The processing of the main routine will be described below. In step S12, the timer for measuring the control cycle ts is reset.

In step S14, the following distance measuring device 1
2. Various input signals supplied from the traveling lane recognition device 14, the vehicle speed meter 16, the operation switch 18, and the various sensor switches 20 are arithmetically processed. Specifically, reading of signals from the operation switch 18, calculation of vehicle speed VS, calculation of throttle opening, calculation of wheel speed, calculation of steering angle,
The road curvature (R) is estimated and calculated, and image controller data is acquired from the CCD camera.

In the next step S16, the data of the preceding vehicle is calculated based on the signal from the scanning type laser radar. Specifically, it is determined whether or not there is a candidate vehicle in the traveling lane, selection of a preceding vehicle when the candidate vehicle is in the traveling lane, and the current inter-vehicle distance DS between the preceding vehicle and the own vehicle.
And the relative speed Vba between the preceding vehicle and the host vehicle, and an inter-vehicle distance warning process for determining whether or not to sound an alarm from the vehicle speed VS and the inter-vehicle distance DS.

In step S18, a failure diagnosis process for a CCD camera, a scan type laser radar or the like is performed. Here, the disturbance of the image signal from the CCD camera, the dirt of the laser radar, etc. are detected and treated as a failure. In step S20, various control data setting processing is performed based on the input signal processing result performed in step S14 and the calculation result of the preceding vehicle data performed in step S16.

Here, first, the driver operates the operation switch 1
The delay time from the preceding vehicle, that is, the inter-vehicle time TC, which is input by operating 8, is set. The inter-vehicle time TC is a value that can be changed according to the operation amount of the operation switch 18, and the value is, for example, 1.
It is set within the range of 5 sec to 2.5 sec. Then, the set inter-vehicle distance Dset between the own vehicle and the preceding vehicle is calculated based on the inter-vehicle time TC, and the safe inter-vehicle distances DSF1, DSF2 are calculated.
Is performed. The set inter-vehicle distance Dset is a threshold value for determining whether or not the preceding vehicle is within the range in which the tracking control described below should be performed, and is set based on the map shown in FIG. As shown in the figure, the set inter-vehicle distance Dset is
The value varies depending on the inter-vehicle time TC, and the value is shown in the range of the inter-vehicle time TC from the value XT1 (for example, 1.5 sec) to the value XT3 (for example, 2.5 sec), that is, the hatched line in the figure. It is set within the range. Normally, the set inter-vehicle distance Dset is the inter-vehicle time TC having a value XT2 (for example, 2.0 sec).
) Value, that is, the value on the thick solid line in the figure is used as the standard value.

The safe inter-vehicle distances DSF1 and DSF2 are used in the control modes such as constant speed control, tracking control, slow deceleration control and deceleration control, which will be described later (see FIG. 4), to ensure a sufficient inter-vehicle distance. This is a threshold value set accordingly. The safe inter-vehicle distance DSF1 is used during constant speed control and tracking control,
The value is set according to the vehicle speed VS at that time from the map 1 shown in FIG. 6 or the map 3 shown in FIG. These maps differ depending on the inter-vehicle time TC, but here the case where the inter-vehicle time TC is the value XT2 (2.0 sec) is shown.

As shown in these figures, the safe inter-vehicle distance D
The value of SF1 also varies depending on the relative speed Vba with the preceding vehicle,
When the relative speed Vba is zero or less (Vba ≦ 0 km), the value is smallest when the relative speed Vba is zero (Vba = 0 km), and the relative speed Vba is XV1 (for example, −10 km), XV2.
It becomes larger as it becomes smaller (for example, -20 km). That is, the greater the degree of approaching the preceding vehicle, the greater the inter-vehicle distance DSF1 for maintaining safety. Map 1 in FIG. 6 is used during tracking control, and map 3 in FIG. 8 is used during constant speed control. In this way, by distinguishing the maps used for the constant speed control and the tracking control, the traveling control can be appropriately executed according to the approaching situation assumed for each. In addition, the thick solid line in the figure is the reference safe inter-vehicle distance DSF1 which is assumed in advance by an experiment,
It is a reference threshold when performing tracking control.

The safe inter-vehicle distance DSF2 is used in the slow deceleration control and the deceleration control, respectively, and its value is set in accordance with the vehicle speed VS at that time from the map 2 shown in FIG. 7 in the same manner as in the case of the safe inter-vehicle distance DSF1. To be done. The processes of steps S14 to S20 described above are performed by the input processing unit 4 of FIG.

In the next step S22, the set inter-vehicle distance Dset and the safe inter-vehicle distances DSF1, DSF obtained as described above are obtained.
This is a step of performing control mode transition processing, that is, selection of a control mode, based on 2 and the current inter-vehicle distance DS.
This processing is executed by the control state calculation unit 6. FIG.
Shows each control mode and its transition in a schematic form, and each control mode and its transition will be described below with reference to FIG.

By the way, in the next step S24, the set vehicle speed Vm which is executed by the control content calculating section 8 when the traveling control is carried out.
Step S26 is for various control output processing, that is, the throttle actuator 30, A / T
32 is a step of performing drive control of each of the brake actuator 34 and the brake actuator 34. However, since these steps are performed according to each control mode, they are also described here.

As shown in FIG. 4, when the power is turned on and the initialization is carried out in step S10, the control mode is the initialization mode M10, and after the initialization processing is completed, the control OFF mode M12 is entered. The control OFF mode M12 is a control mode when the driving control is not performed and the driver performs the normal driving operation as described above.

When the traveling control is started by the operation of the operation switch 18, the control mode to be changed is determined based on the execution of the steps S14, 16 and 20 described above. The vehicle speed VS is within the control feasible range (for example, 40 km / h≤VS≤1
(05 km / h) and the current inter-vehicle distance DS is larger than the set inter-vehicle distance Dset obtained as described above (D
S> Dset), and transits to the constant speed control mode M14. At this time, the current vehicle speed VS is stored in the ECU 2 as the set vehicle speed Vm, and this value is set as the target vehicle speed Vt for running control. (Vt = Vm = VS) In the constant speed control mode M14, the traveling control is performed so as to maintain the target vehicle speed Vt. In the constant speed control mode M14, the operation switch 18 is operated to move once to the speed adjustment mode M16, where the set vehicle speed Vm,
That is, the target vehicle speed Vt can be increased or decreased.

On the other hand, when the current inter-vehicle distance DS is less than or equal to the set inter-vehicle distance Dset (DS ≤ Dset), there is a preceding vehicle. In this case, the control OFF mode M12 transits to the tracking control mode M18. In this tracking control mode M18, the vehicle is operated by the throttle actuator 30.
The above-mentioned map 1 for the inter-vehicle distance with the preceding vehicle by the control of
It keeps running consistently based on. At this time as well, the set vehicle speed Vm is stored based on the current vehicle speed VS, and this value is set as the target vehicle speed Vt for performing the traveling control. Here, when the transition to the tracking control mode M18 is made. A value larger than the vehicle speed VS of the vehicle by α (for example, 10 km / h) is stored in the ECU 2 as the set vehicle speed Vm (Vm =
VS + α). Therefore, when the preceding vehicle accelerates, acceleration and tracking can be performed within the range of α (10 km / h), and good tracking traveling can be performed. On the other hand, since the preceding vehicle is not tracked beyond the set vehicle speed Vm, it is not excessively accelerated due to the sudden acceleration of the preceding vehicle.

In the tracking control mode M18, the inter-vehicle distance adjustment mode M20 is temporarily set by operating the operation switch 18.
And change the inter-vehicle time TC, the set inter-vehicle distance D
It is possible to increase or decrease the set. Further, when the traveling control is started, the inter-vehicle distance DS becomes the safe inter-vehicle distance DSF.
When it is smaller than 1, that is, when the host vehicle is too close to the preceding vehicle, the mode is changed to the slow deceleration control mode M22. In the slow deceleration control mode M22, the control content calculator 8 of the ECU 2 drives the throttle actuator 30 to the closing side to reduce the vehicle speed VS by the action of engine braking. As a result, the inter-vehicle distance from the preceding vehicle can be widened.

In the constant speed control mode M14, the preceding vehicle appears and the inter-vehicle distance DS at that time is the set inter-vehicle distance Dset.
When the following is true (DS ≤ Dset), the control shifts to the tracking control mode M18. As described above, the constant speed control mode M1
4 uses map 3 in FIG. 8 and tracking control mode M18 uses map 1 in FIG.

Constant speed control mode M14 and tracking control mode M
In 18, when the inter-vehicle distance DS becomes smaller than the safe inter-vehicle distance DSF1 (DS <DSF1), the control mode transits to the slow deceleration control mode M22. Slow deceleration control mode M22
When the inter-vehicle distance DS becomes sufficiently large and the current inter-vehicle distance DS becomes equal to or greater than the safe inter-vehicle distance DSF1 (DS ≥DSF1), the tracking control mode M18 is returned to.

If the inter-vehicle distance DS is not widened and is still smaller than the safe inter-vehicle distance DSF2 due to the engine braking function in the slow deceleration control mode M22, the deceleration control mode M24 is entered. This deceleration control mode M2
At 4, the A / T 32 is downshifted and the brake actuator 34 is driven and controlled to control the vehicle speed VS.
To decrease more rapidly.

FIG. 10 is a flowchart of a deceleration control control routine executed by the ECU 2 in the deceleration control mode M24. Hereinafter, description will be given with reference to FIG. In step S40, it is determined whether or not the braking force FB is large. Here, the ECU 2 sets the vehicle speed VS and the relative speed V
The magnitude of the braking force FB is determined by comparing the required brake fluid pressure PN calculated based on ba with a predetermined threshold value P1 (for example, 1 MPa).

When the determination result of step S40 is Yes (affirmative) and the required brake fluid pressure PN is equal to or higher than the threshold value (1 MPa) (PN ≥P1), the process proceeds to step S52, the brake actuator 34 is drive-controlled to perform brake control. To do. On the other hand, the determination result of step S40 is No (negative)
If the required brake fluid pressure PN is smaller than the threshold value (1 MPa), the process proceeds to step S42 and the A / T 32 is downshifted. As a result, the engine braking force can be increased, and the vehicle speed VS can be satisfactorily reduced without controlling the drive of the brake actuator 34. The frequency of use of the brake actuator 34 can be reduced and deterioration of the brake pad (not shown) can be achieved. And brake lamp (not shown)
It can prevent the heavy use of. At this time, the timer is started and the elapsed time tB since the shift down control is started
Time.

In step S44, it is determined whether the inter-vehicle distance DS is smaller than the safe inter-vehicle distance DSF3. The safe inter-vehicle distance DSF3 is obtained from the map 5 in FIG. 9 according to the vehicle speed VS. Also for this map 5, as in the case of the safe inter-vehicle distances DSF1 and DSF2, the relative speed V
The value varies depending on ba, and the value is the relative speed V
The value is smallest when ba is zero (Vba = 0 km), and the relative speed Vba is XV1 (eg, -10 km), XV2 (eg, -2).
0km) and XV3 (for example, -30km), the larger it gets.

The determination result of step S44 is No (negative).
In the case of, it returns to step S42. On the other hand, step S
When the determination result of 44 is Yes (affirmative) and the inter-vehicle distance DS is smaller than the safe inter-vehicle distance DSF3 (DS <DSF3), sufficient braking cannot be performed only by the downshift control of the A / T 32. Therefore, in order to further control the drive of the brake actuator 34, step S46 is performed.
Proceed to.

In step S46, the previous step S42
It is determined whether or not the elapsed time tB when the clocking is started is within a predetermined time tB1. Normally, this predetermined time tB1 is A / T3
Delay time from when the downshift control command 2 is supplied to when the downshift is actually completed (for example, 1se
c) is set. Since the execution cycle of the control routine of the deceleration control is about 26 msec, this deceleration control is repeatedly executed until the elapsed time tB reaches the predetermined time tB1 (1 sec).

The determination result of step S46 is No (negative).
If the elapsed time tB has exceeded the predetermined time tB1 (1 sec), the process proceeds to step S48, in which the brake actuator 34 is drive-controlled and the brake control is performed together with the shift-down control. On the other hand, step S
When the determination result of 46 is Yes (affirmative) and the elapsed time tB has not yet reached the predetermined time tB1 (1 sec), the process proceeds to step S50.

In step S50, the previous step S42
The shift-down control performed in step 1 is released once. And
In the next step S52, the brake actuator 34 is drive-controlled to perform brake control. Here, since the downshift control of the A / T 32 is stopped in step S50, only the brake control is performed. As described above, even when it is determined that the inter-vehicle distance DS is smaller than the safe inter-vehicle distance DSF3 by executing step S44 and the brake control is necessary, the elapsed time tB is still the predetermined time t.
If B1 (1 sec) has not elapsed, that is, A / T32
If the downshift control command is output to the, but the downshift is not yet performed, the downshift control is released so that the downshift is not performed at all. As a result, even when the shift down control and the brake control are to be performed together, the brake control is always started after the completion of the shift down, and the shift down timing and the brake control start timing are It does not overlap. Therefore, A / T3
The second shift shock and the brake shock due to the operation of the brake actuator 34 do not occur at the same time, and the traveling feeling is not deteriorated.

When the traveling control is executed in the deceleration control mode M24 in this way, the inter-vehicle distance from the preceding vehicle can be increased in a short time. When the current inter-vehicle distance DS becomes equal to or greater than the safe inter-vehicle distance DSF2 (DS ≧ DSF2),
The process returns to the slow deceleration control mode M22. Tracking control mode M18
Or slow deceleration control mode M22 or deceleration control mode M24
If the preceding vehicle changes lanes or the like and suddenly disappears from the front while traveling control is performed, the inter-vehicle distance DS is infinite (DS = ∞). In this case, The vehicle speed holding mode M26 is entered.

In the vehicle speed holding mode M26, the vehicle speed VS at the time when the preceding vehicle is lost is set as the holding vehicle speed Vh, and the holding vehicle speed Vh is stored as the target vehicle speed Vt (Vt = Vh = V
S), the target vehicle speed Vt is set to a predetermined time t2 (for example, 3se
It is designed to be held for c). By the way, when the vehicle is traveling in the tracking control mode M18, the slow deceleration control mode M22, or the deceleration control mode M24, the throttle actuator 30, the A / T 32, and the brake actuator 34 are operating, and the vehicle is not accelerated or decelerated. Has been done. Therefore, as described above, if the vehicle speed VS at the time when the preceding vehicle is lost is set to the target vehicle speed Vt as it is, the acceleration / deceleration vehicle speed VS does not suddenly reach the target vehicle speed Vt due to the action of inertial force, and overshoot or It will cause an undershoot.

Therefore, in this vehicle speed holding mode M26,
The target vehicle speed Vt is set according to the acceleration / deceleration state of the vehicle. FIG. 11 shows a flowchart of a control routine for vehicle speed maintenance control executed by the ECU 2.
Based on the figure, the target vehicle speed V in the vehicle speed holding mode M26
How to set t is explained. In step S60,
The target vehicle speed Vt is set to the vehicle speed VS when the preceding vehicle lost.

In step S62, it is determined whether or not the vehicle acceleration GS is within a predetermined range, and if it is outside the predetermined range, it is further determined whether it is larger or smaller than the predetermined range. This predetermined range is from the value GS1 (for example, -0.01G) to the value GS2.
(For example, 0.01 G). Acceleration GS is
It is calculated based on the vehicle speed VS. As a result of the determination in step S62, the acceleration GS is the value GS1 (for example, -0.01G).
And within the predetermined range of the value G S2 (for example, 0.01 G), the process proceeds to step S68.

Step S68 is a step for resetting the current vehicle speed VS to the target vehicle speed Vt. Here, the target vehicle speed Vt set in step S60, that is, the vehicle speed VS at the time when the preceding vehicle is lost is set as it is as the target vehicle speed Vt. As a result of the determination in step S62, if the acceleration GS is equal to or less than the value GS1 (-0.01 G) (GS ≤ GS1), that is, if the vehicle is decelerating and the vehicle speed VS undershoots, the next step Proceed to S64.

In step S64, the acceleration GS
Is greater than the value GS1 (-0.01 G). If the determination result is No (negative), the execution of step S64 is repeated. On the other hand, if the determination result is Yes (affirmative) and it is determined that the acceleration GS is larger than the value GS1 (-0.01 G), the process proceeds to step S68.

Step S68 is a step for resetting the target vehicle speed Vt as described above. Here, the current vehicle speed VS is newly set as the target vehicle speed Vt. At this time, since the vehicle is undershooting, the current vehicle speed VS is the target vehicle speed Vt set in step S60.
Is smaller than the target vehicle speed Vt, and the vehicle speed VS smaller than the target vehicle speed Vt becomes the new target vehicle speed Vt.

As a result of the determination in step S62, when the acceleration GS is the value GS2 (0.01 G) or more (GS ≥GS2), that is, when the vehicle is accelerating and the vehicle speed VS is overshooting, It proceeds to step S66. In step S66, the acceleration GS is now the value GS2 (0.01
It is determined whether or not it is smaller than G). Judgment result is N
In the case of o (negative), the execution of step S66 is repeated. On the other hand, when the determination result is Yes (affirmative) and it is determined that the acceleration GS is smaller than the value GS2 (0.01G), the process proceeds to step S68.

At this time, since the vehicle is overshooting, the current vehicle speed VS is larger than the target vehicle speed Vt set in step S60. Therefore, in step S68, this target vehicle speed Vt is exceeded. Sets a large vehicle speed VS as a new target vehicle speed Vt. FIG.
FIG. 2 is a diagram showing a change with time of the vehicle speed VS when the vehicle speed holding control is performed while the vehicle is accelerating. As shown in the figure, for example, when the tracking control mode M18 is changed to the vehicle speed holding mode M26, the vehicle speed VS is once set to the target vehicle speed V.
When set to t (indicated by the broken line), the vehicle speed VS is the acceleration G
Hold S to overshoot. However, when the overshoot reaches the apex and the acceleration GS is within the predetermined range, the vehicle speed VS at that time is newly set to the target vehicle speed V.
Reset as t.

In this way, in the case where the tracking control mode M18, the slow deceleration control mode M22, or the deceleration control mode M24 transits to the vehicle speed holding mode M26, the target vehicle speed Vt is once set and then according to the acceleration GS. Since the target vehicle speed Vt is set again, the vehicle speed VS changes smoothly, the traveling feeling is not deteriorated, and good traveling can be obtained.

Incidentally, in FIG. 13, for reference, the vehicle speed holding control, that is, the target vehicle speed Vt is not reset and the target vehicle speed V
The time change of the vehicle speed VS when t is set is shown. If the vehicle speed holding control is not performed, the vehicle speed VS will overshoot and then return to the target vehicle speed Vt as shown in the figure. As a result, the vehicle lacks running stability and the driving feeling is poor.

In the vehicle speed holding mode M26, a predetermined time t
When 2 (3 sec) has elapsed, the process returns to the constant speed control mode M14. When returning from the vehicle speed holding mode M26 to the constant speed control mode M14, first, the vehicle speed VS when the vehicle is lost, that is, the target vehicle speed Vt which is the holding vehicle speed Vh, is held for a predetermined time t3 (for example, 30 seconds) and travels. Controlled. During this period, when the operation switch 18 is resumed, the set vehicle speed Vm set as described above is set.
Return to. On the other hand, a predetermined time t3 (30 sec)
If the resume operation is not performed within this holding vehicle speed V
h is newly stored as the set vehicle speed Vm (Vm = Vt =
Vh = VS) and thereafter, the vehicle is controlled to travel at this new set vehicle speed Vm.

FIG. 14 shows a change over time in the vehicle speed VS which changes according to the control mode in which the above-mentioned transition occurs.
As shown in the figure, the operation switch 1 is operated while traveling at the vehicle speed VSa.
The traveling control is started by the operation of 8, and the constant speed control mode M
At 14, the vehicle speed VSa is stored as the set vehicle speed Vm. At this time, the vehicle runs while maintaining the set vehicle speed Vm as the target vehicle speed Vt. Then, when the constant speed control mode M14 transits to the tracking control mode M18 due to the approach of the preceding vehicle, the vehicle travels in accordance with the speed of the preceding vehicle.

After that, when the preceding vehicle is lost and transits to the vehicle speed holding mode M26, the vehicle uses the held vehicle speed Vh, which is the vehicle speed VSb at that time, as the target vehicle speed Vt for a predetermined time t2.
Drive for 3 seconds. Then, the predetermined time t2 (3
After elapse of sec), the process returns to the constant speed control mode M14. Here, the vehicle travels continuously with the held vehicle speed Vh as the target vehicle speed Vt for a predetermined time t3 (30 sec). When the predetermined time t3 (30 sec) has elapsed, the held vehicle speed Vh which is the vehicle speed VSb is newly stored as the set vehicle speed Vm, and the set vehicle speed Vm is set as the new target vehicle speed Vt and the vehicle travels. On the other hand, when the resume operation is performed by operating the operation switch 18 within the predetermined time t3 (30 sec), the target vehicle speed Vt is set to the initial set vehicle speed Vm as shown by the broken line in the figure.
That is, the vehicle speed becomes VSa, and the vehicle continues traveling at the vehicle speed VSa.

As described above, when returning to the constant speed control mode M14, there is a grace period of a predetermined time t3 (30 sec), and only when the resume operation is performed during this time, the vehicle speed is set to the initial set vehicle speed Vm. Therefore, it is possible to realize smooth and good traveling without the driver feeling unintentional acceleration. Steps S22 to S26
Is executed, then step S28 is executed. This step S28 is a step executed by the display content calculation unit 10, and performs various display and alarm output processing. The output means includes a lamp output, a display output, a buzzer output, and a voice warning output. Specifically, the traveling control operation display lamp 62, the warning buzzer operation lamp 64, the center message display 41, and the vehicle-to-vehicle distance shown in FIG. There is an inter-vehicle distance warning buzzer (not shown) which emits a warning sound based on the inter-vehicle distance warning processing function of the input processing unit 4 when the distance DS becomes smaller than the inter-vehicle distance warning distance. Descriptions of these display contents and the like are omitted here.

[0056]

As is apparent from the above description, claim 1
According to the vehicle travel control device of the vehicle, the vehicle-interval distance measuring unit measures the inter-vehicle distance with the preceding vehicle, and the vehicle-driving control unit controls the vehicle speed so that the measured inter-vehicle distance becomes a predetermined distance. In the travel control device, first deceleration control means for decelerating the vehicle speed by shifting the transmission to a lower speed side when the inter-vehicle distance becomes smaller, and first deceleration control means when the inter-vehicle distance becomes further smaller. Second deceleration control means for decelerating the vehicle speed by braking the wheels together with the deceleration control means, and second deceleration control means for a predetermined time after the deceleration control by the first deceleration control means is started. Since the releasing means for releasing the deceleration control by the first deceleration control means is provided when the deceleration control is started, the driving feeling and the followability to the preceding vehicle are not deteriorated, and the good reduction is achieved. Control can be performed.

In the invention of claim 2, the predetermined time is
Since it is the time from the supply of the gear shift command to the transmission until the gear shift is achieved, the braking of the wheels and the braking by the gear shift can be immediately performed after the gear shift is achieved.

[Brief description of drawings]

FIG. 1 is a system configuration diagram of a travel control device.

FIG. 2 is a view showing the vicinity of an instrument panel.

FIG. 3 is a flowchart showing a control routine of travel control.

FIG. 4 is a diagram showing transition of each control mode.

FIG. 5 is a map showing a relationship between a set inter-vehicle distance Dset and a vehicle speed V.

[Fig. 6] Safe inter-vehicle distance DSF used during tracking control
3 is a map showing the relationship between 1 and vehicle speed VS.

FIG. 7: Safe inter-vehicle distance D used during slow deceleration travel control
6 is a map showing the relationship between SF2 and vehicle speed VS.

FIG. 8: Safe inter-vehicle distance DSF used during constant speed traveling control
3 is a map showing the relationship between 1 and vehicle speed VS.

FIG. 9: Safe inter-vehicle distance DSF used during deceleration control
3 is a map showing the relationship between 3 and vehicle speed VS.

FIG. 10 is a flowchart of a deceleration control routine executed during deceleration control.

FIG. 11 is a flowchart of a vehicle speed holding control routine executed during vehicle speed holding control.

FIG. 12 is a diagram showing a change over time of the vehicle speed VS when the vehicle speed holding control is performed during acceleration of the vehicle.

FIG. 13 is a reference diagram showing a time change of the vehicle speed VS when the vehicle speed holding control is not performed during acceleration of the vehicle.

FIG. 14 is a vehicle speed V that changes according to a control mode in which the vehicle transitions.
It is a figure which shows the time change of S.

[Explanation of symbols]

 2 main control unit (ECU) 4 input processing unit 6 control state calculation unit 8 control content calculation unit 10 display content calculation unit 11 control power switch 12 inter-vehicle distance measurement device 14 traveling lane recognition device 16 vehicle speed meter 18 operation switch 20 various sensor switches Class 30 Throttle actuator 32 Automatic transmission (A / T) 34 Brake actuator 40 Indicator

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Naohiro Kishimoto 5-3-8, Shiba, Minato-ku, Tokyo Mitsubishi Motors Corporation (72) Inventor Takashi Kosaka 5-3-8, Shiba, Minato-ku, Tokyo Mitsubishi Automotive Industry Co., Ltd.

Claims (2)

[Claims] 1. A travel control device for a vehicle, comprising a tracking travel control means for measuring the inter-vehicle distance to a preceding vehicle by the inter-vehicle distance measuring means and controlling the vehicle speed so that the measured inter-vehicle distance becomes a predetermined distance. First deceleration control means for decelerating and controlling the vehicle speed by shifting to a lower speed stage of the transmission when the inter-vehicle distance becomes smaller; and the first deceleration when the inter-vehicle distance becomes smaller. Second deceleration control means for decelerating and controlling the vehicle speed by braking the wheels together with the control means, and the second deceleration control for a predetermined time after the deceleration control by the first deceleration control means is started. A deceleration control for releasing the deceleration control by the first deceleration control means when the deceleration control by the means is started. 2. The vehicle travel control device according to claim 1, wherein the predetermined time period is a time period from when a gear shift command is supplied to the transmission to when the gear shift is achieved.