JP2000326760A - Leading vehicle follow-up control device - Google Patents

Abstract

(57) [Summary] [Problem] To properly shift down on downhill roads,
Prevent shift hunting. When a vehicle follows a preceding vehicle, an inter-vehicle distance sensor detects an inter-vehicle distance and a vehicle speed sensor.
The target vehicle speed is calculated based on the following distance and the own vehicle speed detected by the following distance control unit 40, and the target braking / driving force command value is calculated by the vehicle speed control unit 50 based on the target vehicle speed. . At this time, the robust compensator 51C calculates a disturbance estimation value according to the gradient of the downhill road, and subtracts the disturbance estimation value from the target braking / driving force command value to calculate the target braking / driving force. Control the braking and driving forces of the vehicle. The deceleration force margin calculation unit 52 calculates the deceleration force margin based on the target braking / driving force, and the threshold setting unit 53 calculates the deceleration force margin based on the disturbance estimation value representing the gradient of the downhill road according to the magnitude of the downhill gradient. A shift down threshold is set, and the shift position determination unit 54 compares the deceleration force margin with the shift down threshold to determine the shift position.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a preceding vehicle follow-up control device that recognizes a preceding vehicle and travels following the vehicle while maintaining a constant inter-vehicle distance.

[0002]

2. Description of the Related Art Conventionally, as a preceding vehicle following control device, for example, one described in Japanese Patent Application Laid-Open No. 7-223457 is known. In this conventional example, the downshift condition of the transmission set by any of the following distance, the following distance and the own vehicle speed, and the following distance and the relative speed is individually set according to each of a flat road, an uphill road, and a downhill road. And a preceding vehicle follow-up control device that always sets an appropriate inter-vehicle distance.

[0003]

However, in the above conventional example, it is determined whether the traveling road is a flat road, an uphill road, or a downhill road, and the downshift condition according to these is determined by the road surface gradient. Without considering the actual road gradient and driving conditions, it is not possible to obtain the appropriate timing for downshifting. There is an unresolved issue that does not fit the sense of.

In order to solve this problem, it is conceivable to create a map that covers all road surface gradients and running conditions. However, creating such a map requires an enormous amount of information and cannot be realized. Therefore, the present invention has been made by focusing on the unsolved problem of the above-described conventional example, and a preceding vehicle which can perform optimal shift control by changing a shift threshold value according to a road surface gradient. It is intended to provide a tracking control device.

[0005]

In order to achieve the above object, a preceding vehicle follow-up control device according to a first aspect of the present invention comprises an inter-vehicle distance detecting means for detecting an inter-vehicle distance to a preceding vehicle, and an inter-vehicle distance detecting means. Inter-vehicle distance control means for calculating a target vehicle speed for matching the detected inter-vehicle distance detection value to the target inter-vehicle distance,
Self-vehicle speed detecting means for detecting the own-vehicle speed; and a target braking / driving force for matching the own-vehicle speed detection value detected by the own-vehicle speed detecting means to the target vehicle speed, based on the target braking / driving force. A rotational driving force source, a vehicle speed control unit for controlling a transmission and / or a braking device, and a road surface gradient detecting unit for detecting or estimating a downward gradient of a traveling road surface, wherein the vehicle speed control unit comprises:
Threshold value setting means for setting a downshift threshold value in accordance with the road surface gradient detected or estimated by the road surface gradient detection means; a deceleration force margin calculated based on the target braking / driving force; and the downshift threshold value And a shift position determining means for determining a shift position of the transmission based on the above.

In the invention according to claim 1, the inter-vehicle distance control means calculates a target vehicle speed that matches the inter-vehicle distance with the preceding vehicle to the target inter-vehicle distance, and the vehicle speed control means calculates the target vehicle speed and the detected own vehicle speed. Calculates the target braking / driving force that matches with, and based on the target braking / driving force, controls the rotational driving force of a rotational driving force source such as an engine, controls the braking force of a braking device, and further shifts. Control the shift position of the machine,
Follow-up running control to maintain the target inter-vehicle distance is performed. At this time, in a case where the own vehicle is traveling on a downhill with a downhill slope and a downshift is required, a downshift threshold value corresponding to the downhill slope is set, and the magnitude of the downhill slope is set. The downshift threshold is changed according to
It becomes possible to maintain the proper inter-vehicle distance by changing the ease of downshifting according to the downhill gradient.

According to a second aspect of the present invention, in the preceding vehicle following control apparatus, the threshold value setting means sets the downshift threshold value so that the downshift becomes easier as the road surface gradient becomes larger. It is characterized by being constituted so that. According to the second aspect of the present invention, the downshifting becomes easier as the downhill slope becomes larger, so that the braking load due to the increase in the engine braking force due to the faster downshift is reduced, and the proper inter-vehicle distance can be maintained.

According to a third aspect of the present invention, in the vehicle control system according to the first or second aspect, the threshold value setting means makes it more difficult to upshift after downshifting as the downhill slope of the road surface becomes larger. In which a shift-up threshold is set.
According to the third aspect of the present invention, since the upshift after downshifting is suppressed as the downhill slope of the road is increased, shift hunting can be reliably prevented and the appropriate inter-vehicle distance can be reliably maintained. .

According to a fourth aspect of the present invention, there is provided a preceding vehicle follow-up control device according to any one of the first to third aspects, wherein the road surface gradient detecting means controls the own vehicle speed and the vehicle speed detected by the own vehicle speed detecting means. The present invention is characterized in that it is configured to estimate a road surface down slope from a disturbance estimation value estimated based on the target braking / driving force calculated by the means. According to the fourth aspect of the present invention, since the road downgrade is estimated from a disturbance estimation value estimated based on the own vehicle speed and the target braking / driving force, the road downgrade is separately detected. It is possible to estimate the downward slope of the road surface without providing.

Further, according to a fifth aspect of the present invention, in the preceding vehicle follow-up control device, in the invention according to any one of the first to fourth aspects, the shift position determining means is obtained based on the target braking / driving force. The deceleration force margin is calculated by subtracting the maximum deceleration force calculated based on the target vehicle speed calculated by the inter-vehicle distance control means from the deceleration force request value, and the deceleration force margin is equal to or less than the downshift threshold and The downshift is performed when the relative speed with respect to the preceding vehicle is the approaching direction.

In the invention according to claim 5, in a state where the vehicle is traveling at the current shift position of the own vehicle, for example, overdrive, the vehicle is decelerated to increase the inter-vehicle distance with the preceding vehicle by the engine braking force. When the power margin is reduced to be equal to or less than the downshift threshold and the relative speed with the preceding vehicle is in the approaching direction, that is, the inter-vehicle distance is decreasing, the shift position of the transmission is shifted down to reduce the deceleration force. Increase the margin.

[0012]

According to the preceding-vehicle follow-up control device of the first aspect, when the own vehicle is traveling on a downhill with a down slope, and when downshifting is required, the host vehicle responds to the down slope. By setting the threshold for downshift, the threshold for downshift is changed according to the magnitude of the down slope,
By changing the ease of downshifting according to the downhill slope, it is possible to set the optimal threshold for downshifting according to the downhill slope, and it is possible to maintain an appropriate inter-vehicle distance by downshifting. can get.

According to the preceding vehicle follow-up control device of the second aspect, the downshift becomes easier as the descending gradient becomes larger, so that the margin of the deceleration force due to the faster downshift is improved, and the vehicle is controlled on the downhill road. Therefore, an effect that the proper inter-vehicle distance can be maintained can be obtained. Further, according to the preceding vehicle following control device of the third aspect, since the upshift after downshifting is suppressed as the road surface gradient becomes larger, shift hunting is reliably prevented and the appropriate inter-vehicle distance is ensured. Can be maintained.

Further, according to the preceding vehicle following control device of the fourth aspect, the road surface descending gradient is estimated from the disturbance estimated value estimated based on the own vehicle speed and the target acceleration / deceleration force. The effect of being able to estimate the road surface gradient without providing a detecting means for detecting the road surface gradient is obtained. Further, according to the preceding vehicle following control device of the fifth aspect, the margin of deceleration force for decelerating the vehicle in order to increase the inter-vehicle distance with the preceding vehicle by the engine braking force at the current shift position of the own vehicle is small. When the vehicle speed is equal to or less than the downshift threshold and the relative speed with respect to the preceding vehicle is in the approaching direction, that is, the inter-vehicle distance is decreasing, the shift position of the transmission is shifted down to increase the deceleration margin. Therefore, there is an effect that the downshift can be performed only when the downshift is required without inadvertently downshifting.

[0015]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic configuration diagram showing one embodiment of the present invention, in which 1FL and 1FR are front wheels as driven wheels, 1RL and 1RR are rear wheels as driving wheels, and rear wheels 1RL and 1RR. The driving force of the engine 2 is transmitted through the automatic transmission 3, the propeller shaft 4, the final reduction gear 5, and the axle 6, and is driven to rotate.

Front wheels 1FL, 1FR and rear wheels 1RL, 1R
R is provided with a disc brake 7 for generating a braking force, and the braking oil pressure of the disc brake 7 is controlled by a braking control device 8. Here, the braking control device 8 generates a braking oil pressure in response to the depression of a brake pedal (not shown) and, when the target driving force F ^* from the tracking control controller 20 is a negative value, It is configured to generate a braking hydraulic pressure.

The engine 2 is provided with an engine output control device 9 for controlling the output. The engine output control device 9 controls the engine output by controlling the engine speed by adjusting the opening of the throttle valve and adjusting the opening of the idle control valve to control the engine speed by controlling the engine speed. Although a control method is conceivable, in the present embodiment, a method of adjusting the opening of the throttle valve is employed.

Further, the automatic transmission 3 is provided with a transmission control device 10 for controlling the shift position. When the OD prohibition control signal CS having the logical value “1” is input from the following control controller 20 described below, the transmission control device 10 responds to the input of the OD prohibition control signal CS in the fourth speed (O
D) Shifting in the gear position is prohibited, the gear is shifted down to the third gear position, and in the state where the gear is shifted down to the third gear position, when the OD inhibition control signal CS returns to the logical value “0”, It is configured to shift up to the fourth gear position.

On the other hand, an inter-vehicle distance sensor 12 comprising a radar device as an inter-vehicle distance detecting means for detecting an inter-vehicle distance L from a preceding vehicle is provided below the vehicle body on the front side of the vehicle. The inter-vehicle distance sensor 12 is, for example, a radar device that measures the inter-vehicle distance L between the preceding vehicle and the own vehicle by sweeping a laser beam forward and receiving reflected light from the preceding vehicle, or a radio wave or an ultrasonic wave. A distance sensor that measures the inter-vehicle distance L by utilizing the distance sensor can be applied.

Further, the vehicle is provided with a vehicle speed sensor 13 for detecting the own vehicle speed V by detecting the rotation speed of an output shaft provided on the output side of the automatic transmission 3. The output signals of the inter-vehicle distance sensor 12 and the vehicle speed sensor 13 are input to the follow-up control controller 20, and the following-up control controller 20 causes the inter-vehicle distance sensor 12 to output signals.
By controlling the braking control device 8, the engine output control device 9 and the transmission control device 10 based on the following distance L detected by the vehicle and the own vehicle speed V detected by the wheel speed sensor 13, appropriate The following vehicle running while maintaining a suitable inter-vehicle distance, and during the following traveling control, when the preceding vehicle runs on a downhill road, a downshift threshold value and an upshift The shift position of the automatic transmission 3 is controlled by setting a threshold value.

This tracking control controller 20 is shown in FIG.
As shown in the figure, the distance measurement signal processing unit 2 measures the time from when the laser beam is scanned by the inter-vehicle distance sensor 12 to when the reflected light of the preceding vehicle is received, and calculates the inter-vehicle distance L from the preceding vehicle.
1, a vehicle speed signal processing unit 30 for measuring the period of the vehicle speed pulse from the vehicle speed sensor 13 and calculating the own vehicle speed Vs, and an inter-vehicle distance L and vehicle speed signal processing unit 30 calculated by the ranging signal processing unit 21 An inter-vehicle distance control unit 40 that calculates a target vehicle speed V ^* for maintaining the inter-vehicle distance L at the target inter-vehicle distance L ^* based on the obtained own vehicle speed Vs, and a target vehicle speed calculated by the inter-vehicle distance control unit 40 Vehicle speed control as vehicle speed control means for controlling the braking control device 8, the engine output control device 9, and the shift control device 10 based on V ^* and the relative speed ΔV so that the own vehicle speed matches the target vehicle speed V ^*. And a unit 50.

The inter-vehicle distance control unit 40 includes a ranging signal processing unit 2
Relative to the preceding vehicle based on the following distance L input from 0
A relative speed calculator 41 for calculating a speed ΔV;
Based on the own vehicle speed Vs input from the
Target inter-vehicle distance L to own vehicle ^*Calculate the target following distance
The relative speed calculated by the setting unit 42 and the relative speed calculation unit 41
The target vehicle calculated by the degree ΔV and the target inter-vehicle distance setting unit 42
Distance L^*The target vehicle distance L is calculated based on^*To
Target vehicle speed V for matching^*Distance calculation to calculate
And a portion 43.

Here, the relative speed calculating section 41 is constituted by a band-pass filter for performing, for example, a band-pass filter processing on the inter-vehicle distance L inputted from the distance measuring signal processing section 20. The transfer function of this bandpass filter can be represented by the following equation (1), and the numerator has a differential term of the Laplace operator s. Is calculated.

F (s) = ω _C ² s / (s ² + 2ζω _C s + ω _C ² ) (1) where ω _C = 2πf _C , and s is a Laplace operator. Thus, by using a bandpass filter,
As in the case where the relative speed ΔV is calculated by performing a simple differential operation from the amount of change in the inter-vehicle distance L per unit time, the vehicle is susceptible to noise and easily affects the vehicle behavior, such as wobbling during tracking control. That can be avoided.
Note that the cutoff frequency f _C in the equation (1) is determined by the magnitude of the noise component included in the inter-vehicle distance L and the allowable value of the short-period acceleration fluctuation before and after the vehicle body. Further, in calculating the relative speed ΔV, instead of using a bandpass filter, a differentiation process may be performed with a high-pass filter that performs a high-pass filter process on the inter-vehicle distance L.

The target inter-vehicle distance setting section 42 calculates a preceding vehicle speed Vt calculated by adding the relative speed ΔV to the own vehicle speed Vs.
(= Vs + ΔV) and the current vehicle is L behind the current preceding vehicle.
Time T ₀ to reach the position of _S [m] (inter-vehicle time)
Then, the target inter-vehicle distance L ^* between the preceding vehicle and the host vehicle is calculated according to the following equation (2). L ^* = Vt × T ₀ + L _s (2) By adopting the concept of inter-vehicle time, the inter-vehicle distance is set to increase as the vehicle speed increases. L _S is the inter-vehicle distance when stopped.

The inter-vehicle distance calculating unit 43 further calculates a target vehicle speed V ^* for following the vehicle while maintaining the inter-vehicle distance L at the target value L ^* based on the inter-vehicle distance L, the target inter-vehicle distance L ^* and the relative speed ΔV ^. Is calculated. Specifically, the following (3)
As shown in the equation, a value obtained by multiplying a deviation (L ^* −L) between the target inter-vehicle distance L ^* and the actual inter-vehicle distance L by a distance control gain fd,
The target relative speed ΔV ^* is obtained by a configuration including a linear combination with a value obtained by multiplying the relative speed ΔV by the speed control gain fv, and the preceding vehicle speed Vt (= Vs) is obtained as shown in the following equation (4).
+ ΔV) minus the target relative speed ΔV ^* to obtain the target vehicle speed V ^*
Is calculated.

ΔV^*= Fd (L^*−L) + fv · ΔV (3) V^*= Vt-ΔV^* (4) The vehicle speed control unit 50 receives the input target vehicle speed V.^*Vehicle speed V
driving force command value F for matching s_ORAnd disturbance estimates
d_V′ Is calculated, and the target braking / driving force F obtained by the deviation is
^*And a vehicle speed servo unit 51 for calculating the vehicle speed
Target braking / driving force F calculated in 1^*And the target vehicle mentioned above
Speed V^*Deceleration force margin F based on_DMCalculate the residual deceleration force
Disturbance calculated by the tolerance calculation unit 52 and the vehicle speed servo unit 51
Estimated value d _V′ Based on the downshift threshold TH_Das well as
Upshift threshold TH_USetting section 53 for setting
And the deceleration force margin calculated by the deceleration force margin calculation unit 52
F_DM, The downshift threshold set by the threshold setting unit 53
TH_D, Upshift threshold TH_UAnd relative speed calculator
The shift position is determined based on the relative speed ΔV calculated in 41.
And a shift position judging section 54 for making a disconnection.

Here, the vehicle speed servo unit 51 is shown in FIG.
Thus, for example, the robust model matching control method
Having a configuration of a vehicle speed servo system,
Target vehicle speed V to be input^*Control / driving force command value F based on
_ORAnd a model matching compensator 51A that calculates
The braking / driving force finger calculated by the Dell matching compensator 51A
Quotation F_ORDisturbance estimated value d calculated by self_V′
And target driving force F^*And a subtractor 51B for calculating
Target braking / driving force F output from subtractor 51B ^*And own car
Disturbance estimated value d based on speed Vs_V'To calculate ′
And the target braking / driving force F^*
Is supplied to the vehicle to be controlled as an operation amount. here,
The vehicle to be controlled has the target braking / driving force F^*Is the manipulated variable, and
Formulation model of transfer function Gv (s) using vehicle speed Vs as control amount
The transfer characteristic Gv (s) is expressed as
It does not include the dead time element.

The model matching compensator 51A is a compensator for matching the response characteristics of the vehicle speed servo system to the reference model, and is a reference model R ₂ (s) of the feedforward section.
In setting the input and output response characteristic, determines a disturbance removing function and stability by reference model R ₁ of the feedback unit (s), calculates a target vehicle speed V ^* and the vehicular velocity Vs and Kara braking-driving force command value F _OR I do.

The robust compensator 51C includes a braking / driving force limiter 51a for limiting the input target braking / driving force F ^* to a maximum driving force and a maximum braking force that can be actually generated in the vehicle;
Based on the output of the driving force limiter 51a, a low-pass filter 51b for obtaining a braking / driving force F1 including a current actual road gradient, a modeling error, and the like, and the own vehicle speed Vs are input.
A compensator 51c that applies a low-pass filter to the inverse system of the vehicle model (H (s) / Gv (s)) to obtain a braking / driving force F2 for maintaining the current vehicle speed Vs, and a compensator 51c And a subtractor 51d for subtracting the braking / driving force F1 output from the low-pass filter 51b from the braking / driving force F2 output from the controller 51. The subtractor 51d estimates a disturbance including a road surface gradient, a modeling error, and the like. The value d _V 'is output. Since the modeling error included in the disturbance estimation value d _V ′ is absorbed by the running resistance on a flat road surface, a change in the road surface gradient substantially appears as the disturbance estimation value.

The target output from the subtractor 51B
Braking / driving force F^*Is the braking control device 8 and the engine output control
The braking control device 8 supplies the target braking / driving
Force F ^*Is a negative value and the braking force range by engine brake
Is smaller than a predetermined value set near the lower limit of
To generate braking force according to the magnitude
Control the engine pressure by controlling the braking pressure of the disc brake 7
In the device 9, the target braking / driving force F^*Is positive,
Throttle to generate driving force according to its magnitude
Control the throttle opening.
Control to the closed state.

As shown in FIG. 3, the deceleration force margin calculating section 52 sets the target braking / driving force F ^* to, for example, 0.5 to prevent frequent downshifts and shift hunting.
A low-pass filter 52a outputs a deceleration force demand value F _D by performing low-pass filtering of the order of Hz, the target vehicle speed V
^* Is input, and based on this, the maximum deceleration α is referred to by referring to a characteristic storage table showing the relationship of the deceleration α to the vehicle speed V when the throttle valve is fully closed at the fourth speed (OD).
_A maximum deceleration calculation unit 52b for calculating _MAX , and a value obtained by dividing the vehicle mass M by the total reduction ratio (fourth gear ratio × final gear ratio) to the maximum deceleration α _MAX calculated by the maximum deceleration calculation unit 52b. maximum deceleration force and multiplying unit 52c for calculating the F _DMAX, subtraction of calculating the maximum deceleration force F _{DM AX} the deceleration force margin F _DM and subtracted from the deceleration force demand value F _D of the multiplication to the fourth speed (OD) Device 52d.

Further, the threshold setting unit 53 receives the disturbance estimation value d _V ′ substantially representing the road surface gradient output from the robust compensator 51C, and based on the disturbance estimation value d _V ′ shown in FIG. Referring to characteristic storage table showing the relationship between d _V 'with a threshold value for downshift TH _D and the upshift threshold value TH _U, calculates a threshold value TH _D and the threshold TH _U upshift downshift.

Here, as shown in FIG. 4, the characteristic storage table becomes the maximum value TH _DMAX when the downshift threshold TH _D is a flat road, that is, when the down slope is 0%, and then the down slope is about 4%. Up to 4%
Decreases at a relatively steep slope in the range of 14%, expressed again very gradually drop characteristic line LD 14% or more, the threshold value TH _U for upshift, when downward slope is 0% The maximum value TH _{UMAX which is} about twice the maximum value TH _DMAX of the down-shift threshold TH _D is obtained, and thereafter, the descending gradient decreases relatively slowly until approximately 4%, and decreases with a slightly steep gradient in the range of 4 to 14%. , 14% or more, and is represented by a characteristic line LU which prices very slowly, and the difference between the down-shift threshold TH _D and the up-shift threshold TH _U increases as the downward gradient increases from 4% to 14%. Is set.

The shift position judging section 54 calculates the relative speed ΔV calculated by the relative speed calculating section 41 of the following distance control section 30,
Deceleration force margin calculating section 52 deceleration force margin F _DM calculated in a set threshold value for the downshift threshold TH _D and upshift TH _U at the threshold setting unit 53 is inputted, the overdrive based on these It is determined whether the shift to OD is permitted.

The shift position judging section 54 executes a shift position judging process which is performed as a timer interrupt process every predetermined time (for example, 10 msec) as shown in FIG. step a deceleration force margin F _DM calculated by the calculation section 52 reads, then the processing proceeds to step S2, crowded read the set threshold value TH _D and the threshold TH _U for the upshift downshift threshold setting unit 53 Move to S3.

In step S3, the transmission control device 1
The current gear position information input from 0 is read, and it is determined whether this is the fourth speed (OD) gear position or the third speed gear position. When the current gear position information is the fourth speed gear position, the process proceeds to step S4, The deceleration margin _FDM is equal to the downshift threshold TH.
It determines whether or less _D, and when an F _DM> TH _D, it is judged that the deceleration force margin is enough to end the timer interrupt process is immediately, when it is F _DM ≦ TH _D is When it is determined that there is no deceleration force margin, the process proceeds to step S5, and it is determined whether the relative speed ΔV is “0” or negative. When ΔV> 0, the vehicle speed of the preceding vehicle is higher, When the inter-vehicle distance L becomes longer, it is determined that deceleration control is not necessary, and the timer interrupt processing is terminated as it is. When ΔV ≦ 0, the inter-vehicle distance L becomes shorter and the vehicle is approaching. When it is determined that the control is necessary, the process proceeds to step S6 to cancel the fourth speed (OD) gear position. For example, an OD inhibition control signal C having a logical value "1"
After outputting S to the transmission control device 10, the timer interruption process is terminated.

Further, the determination result in the step S3, when the gear position is the third gear position, the process proceeds to step S7, whether the deceleration force margin F _DM is the upshift threshold value TH _U or judgment, when it is F _DM <TH _U is to immediately terminated timer interrupt processing determines also be returned to the fourth gear position that there is no deceleration force margin, F _DM ≧ T
H when it is _U, it is judged that even to return to the fourth speed gear position there is sufficient deceleration force margin goes to step S8, the setting value ΔVs the relative velocity ΔV is preset (e.g. -3km / h) It is determined whether or not ΔV <ΔV
If s, it is determined that the vehicle is approaching the preceding vehicle, and the timer interrupt process is terminated.
When ΔV ≧ ΔVs, it is determined that the approach to the preceding vehicle has almost stopped, and the process shifts to step S9 to determine whether the disturbance estimated value d _V ′ representing the road surface gradient is less than the set value θs. When d _V ′ ≧ θs, it is determined that the downhill traveling state is continued, and the timer interrupt processing is terminated as it is. When d _V ′ <θs, the vehicle returns to the substantially flat road traveling state. Then, the process proceeds to step S10, and outputs an OD prohibition control signal CS of, for example, a logical value "0" allowing the return to the fourth gear position to the transmission control device 10, and then executes the timer interrupt processing. finish.

The shift position determining means is constituted by the deceleration force margin calculating unit 52, the threshold value setting unit 53, and the shift position determining unit 54. Next, the operation of the above embodiment will be described. Now, when the vehicle is on a downhill road with a relatively small downward gradient and there is no preceding vehicle, and the automatic transmission 3 is in the fourth speed (O
D) It is assumed that the vehicle is traveling at a constant speed, for example, at a set vehicle speed of 100 km / h as shown at a time point t1 in FIG. In this traveling state, there is no preceding vehicle, so the inter-vehicle distance L detected by the inter-vehicle distance sensor 12 is infinite, but since a limiter not shown is provided, as shown in FIG. Since the inter-vehicle distance L is maintained at the maximum value of 120 m, the target inter-vehicle distance L ^* set by the target inter-vehicle distance setting unit 42 is as shown in FIG.
6B, the relative speed ΔV calculated by the relative speed calculator 41 is maintained at “0” as shown in FIG. 6C, and the deceleration force margin is calculated. Part 5
Deceleration force margin F _DM output from the second subtractor 52d has become a so +800 (N) degrees as shown in FIG. 6 (d), a throttle opening calculated by the engine output control unit 9 in accordance with this The degree TVO is set to about 8 degrees as shown in FIG. 6E, and the gear position in the automatic transmission 3 is
As shown in (e), it is set to the fourth speed (OD) gear position. Further, since the vehicle is traveling on a downhill road with less downward slope, and the disturbance estimated value becomes positive relatively large value from the robust compensator 51C corresponding to the magnitude of the falling slope d _V 'is output, since this is subtracted from the model matching compensator system 51A is the output-driving force command value F _OR subtractor 51B, target braking-driving force is outputted from the subtracter 51B F ^* is running on a flat horizontal road This value is smaller than that in the case where the vehicle is running, and the acceleration due to the downhill is offset.

Therefore, in the threshold setting section 53, since the disturbance estimation value d _V ′ is small at a small descending gradient,
The shift-down threshold value TH _D is calculated with reference to the characteristic storage table is set as a relatively large value close to a flat road, but the threshold for upshifting TH _U also smaller than the threshold value TH _D shift down Comparison It is set as a target value.

In this state, at time t2, the vehicle speed shown by the one-dot chain line in FIG. 6A catches up with the preceding vehicle traveling at a constant speed of, for example, 70 km / h, and the preceding vehicle calculated by the relative speed calculating unit 41. Is assumed to be −8 m / s, the target vehicle speed V ^* calculated by the inter-vehicle distance control unit 43 is gradually reduced as shown by the broken line in FIG. Target braking / driving force F calculated by vehicle speed servo unit 51
^As shown in FIG. 6D, the throttle opening TVO is sharply controlled by the engine output control device 9 in the closing direction as shown in FIG. When the target braking / driving force F ^* becomes a negative value at t3,
The throttle opening TVO is controlled to a fully closed state, and a braking force by the engine brake is generated.

At this time, since the host vehicle is traveling on a flat horizontal road, the host vehicle speed Vs gradually decreases as the target vehicle speed V ^* decreases as shown in FIG. As shown in FIG. 6 (c), ΔV also gradually moves in a direction to eliminate the speed difference from the preceding vehicle. On the other hand, the deceleration force demand value F _D, which is low-pass filtered in low-pass filter 52a in the deceleration margin calculator 52, FIG. 6
As shown by the broken line in FIG. 6D, the target braking / driving force F ^* gradually decreases with a phase delay with respect to the decrease, and the deceleration force margin _FDM is correspondingly shown in FIG. as the reduced with a offset of maximum deceleration force F _DMAX component relative deceleration force demand value F _D.

[0043] When the deceleration margin F _DM at time t4 is smaller than the threshold value TH _D downshift, the shift position control processing of FIG. 5, the process proceeds from step S5 to step S6, the logical value "1" of the The OD prohibition control signal CS is output to the transmission control device 10, and accordingly, the automatic transmission 3 is shifted down from the fourth gear position to the third gear position,
The braking force by the engine brake is increased.

[0044] Thus, the host vehicle speed Vs is closer to the target vehicle speed V ^*, the inter-vehicle distance L also without significantly below the target inter-vehicle distance L ^*, follows the target inter-vehicle distance L ^*. Then, the target braking / driving force F ^* tends to increase due to a decrease in the own vehicle speed Vs due to an increase in the braking force by the engine brake, and accordingly, the margin of the deceleration force also gradually increases. Even if the state exceeds the threshold value TH _D , in the shift position control process of FIG. 5, since the shift gear position is the third speed gear position, the process shifts from step S3 to step S7, where the shift gear position is set to a value larger than the shift down threshold value TH _D. because does not exceed the upshift threshold TH _U, it maintains the third speed gear position.

[0045] Then, over deceleration force margin at the time t6, the upshift threshold TH _U, and the relative velocity ΔV is the set value ΔVs above, and travels less descending the slope of the descending slope, the estimated disturbance value d _V ′ is substantially “0” and the set value θ
s, the process proceeds to step S10 via steps S7 to S9, and sets the OD inhibition control signal CS to the logical value “0”.
As a result, the automatic transmission 3 is returned to the fourth speed (OD) gear position by the transmission control device 10.

At this time, the own vehicle speed Vs falls below the vehicle speed of the preceding vehicle, but the target braking / driving force F ^* becomes a positive value at a later time t7, so the engine output control device 9 sets the throttle opening TVO. Gradually increases, the own vehicle speed Vs increases, and when the inter-vehicle distance L matches the target inter-vehicle distance L ^* , the own vehicle speed Vs substantially coincides with the vehicle speed of the preceding vehicle, and the vehicle is in the following running state.

As described above, when the vehicle is traveling on a downhill with a gentle downhill gradient, the downshift threshold T set by the threshold setting unit 53 is set because the downhill gradient is small.
H _D becomes a large value, the fourth speed (OD) shift down deceleration force margin F _DM from the running state at the gear position to the third gear position is not performed until significantly reduced, performed inadvertent downshift Therefore, it is possible to perform an appropriate downshift without giving the driver a feeling of strangeness.

On the other hand, a relatively steep descending gradient (for example, 15 °
When the preceding vehicle is supplemented while the vehicle is traveling on a downhill road, the estimated disturbance value d _V ′ output from the robust compensator 51C becomes a relatively large positive value corresponding to the descending slope. threshold for about half of the down-shifting of the gradual downward slope in accordance with the magnitude of the down slope at the threshold setting unit 53 TH _D and the threshold TH _U shift-up is set according to input these to the shift position determining section 54 Therefore, as shown in FIG. 7A, the shift-down threshold value TH _D becomes a small value close to “0” as shown by the dashed line, and the target braking / driving force F ^* is also a disturbance estimated value. Since the deceleration force margin _FDM is also reduced by the value smaller by _dV ', the deceleration force margin _FDM is faster at the time point t4' as compared with the case where the deceleration force margin _FDM runs gently on the downward slope. Below the shift down threshold value TH _D That is, as shown in FIG. 7B, the gear is shifted down from the fourth gear position (OD) to the third gear position earlier. For this reason, the braking force of the large engine brake can be applied early, and it is possible to reliably prevent the distance between the vehicle and the preceding vehicle from suddenly shortening on a downhill road with a large descending gradient and giving the driver an uncomfortable feeling. it can.

Thereafter, when the vehicle continues to travel on a downhill road in which the descending slope continues to be larger than the set value θs, the time t5 '
In even when deceleration force margin F _DM is a state above the threshold for upshifting TH _U, the shift position control processing of FIG. 5, as by terminating the timer interrupt routine from step S9, the third speed gear position Thus, shift hunting on a downhill road can be reliably prevented.

Further, in the state where the gear is shifted down to the third gear position, the descending gradient of the downhill road becomes small, and the estimated disturbance d
_{When V} ′ becomes a small value and falls below the set value θs, in step S9 in the shift position control process of FIG.
From step S10 to output the OD prohibition control signal CS having the logical value "0" to the transmission control device 10, thereby returning the gear position of the automatic transmission 3 to the fourth speed (OD) gear position. .

When traveling on a flat horizontal road,
Shift down threshold TH _D set by threshold setting section 53
And as compared with the case where the shift-up threshold value TH _U is traveling descends slowly, by a large value, it becomes more downshift difficult conditions, to prevent inadvertent downshift, the driver a sense of discomfort It can be reliably prevented from being given.

As described above, according to the above embodiment, the shift-down threshold TH _D and the shift-up threshold TH _U are changed according to the magnitude of the down slope of the downhill road. By reducing the threshold TH _D and the shift-up threshold TH _U to facilitate down-shifting, speed up the down-shift timing, increase the braking force by the engine brake, and improve the following running performance. Can be.

Further, as the downhill slope increases, the shift-down threshold TH _D and the shift-up threshold TH _U
Is set so as to increase, so that as the descending gradient increases, it becomes more difficult to upshift after downshifting, and shift hunting can be reliably prevented. Further, as a condition for shifting up after downshifting on a downhill road, a case where the down slope is less than the set value θs is added. Thus, the downshift state is continued, and shift hunting can be reliably prevented.

[0054] In the above embodiment, the threshold value TH _D and the threshold TH _U shift-up shift down depending on the value of the magnitude of the falling slope i.e. disturbance estimate d _V 'successively with the threshold value setting unit 53 has been described for changing, it is not limited thereto, the threshold value TH _D and the threshold TH _U shift-up shift down may be changed stepwise in accordance with an increase in the downward slope.

Further, in the above-described embodiment, a case has been described in which the descending slope of the downhill road is estimated by the disturbance estimation value d _V 'output from the robust compensator 51C. However, the present invention is not limited to this. A gauge may be installed on the vehicle body to directly measure the descending slope of the downhill road, or the previously measured slope information is stored in a car navigation system or the like, and the descending slope is used by using the slope information. You may make it detect.

Further, in the above embodiment, the case where the downshift and the upshift are performed between the fourth speed (OD) gear position and the third speed gear position has been described. However, the present invention is not limited to this. Shift down and shift up may be performed between other gear positions,
Further, the present invention can be applied to other transmissions such as an automatic transmission other than an automatic transmission with an overdrive, a belt-type continuously variable transmission, a toroidal continuously variable transmission, and the like.

Furthermore, in the above-described embodiment, the case has been described in which the inter-vehicle distance control unit 40 and the vehicle speed control unit 50 are configured by hardware, but these may be configured by software by arithmetic processing using a microcomputer. Similarly, the case where the shift position control process of FIG. 5 is performed by the shift position determination unit 54 has been described. However, the present invention is not limited to this, and an electronic circuit combining a comparator, an OR circuit, and the like. May be configured.

Furthermore, in the above-described embodiment, a case has been described in which the brake control device 7 for controlling the disc brake 7 during deceleration control is also controlled. However, the present invention is not limited to this. May be omitted, and the braking control may be performed by closing the throttle valve and using the engine braking force due to the downshift of the automatic transmission 3.

In the above embodiment, the case where the present invention is applied to a rear wheel drive vehicle will be described. However, the present invention can also be applied to a front wheel drive vehicle, and the engine 2 is applied as a rotary drive source. Although the case has been described, the present invention is not limited to this, and an electric motor can be applied. Further, the present invention can be applied to a hybrid vehicle using an engine and an electric motor.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing an embodiment of the present invention.

FIG. 2 is a block diagram showing a specific configuration of a tracking control controller of FIG. 1;

FIG. 3 is a block diagram showing a specific configuration of a vehicle speed servo unit of the tracking control controller of FIG. 2;

FIG. 4 is an explanatory diagram showing a characteristic storage table showing a relationship between a down slope of a threshold setting unit and a shift down threshold and a shift up threshold;

FIG. 5 is a flowchart illustrating an example of a shift position determination process executed by a shift position determination unit.

FIG. 6 is a time chart for explaining an operation when the vehicle travels on a gentle downhill slope according to the present invention.

FIG. 7 is a time chart for explaining an operation when the vehicle travels on a steep downhill road according to the present invention.

[Explanation of symbols]

 Reference Signs List 2 engine 3 automatic transmission 7 disc brake 8 braking control device 9 engine output control device 10 transmission control device 12 inter-vehicle distance sensor 13 vehicle speed sensor 20 follow-up control controller 40 inter-vehicle distance control unit 41 relative speed calculation unit 42 target inter-vehicle distance setting Unit 43 inter-vehicle distance calculation unit 50 vehicle speed control unit 51 vehicle speed servo unit 52 deceleration force margin calculation unit 53 threshold value setting unit 54 shift position determination unit

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI theme coat ゛ (reference) // F16H 59:44 59:66 F term (reference) 3D041 AA41 AA67 AB00 AC15 AD04 AD46 AD47 AD51 AE32 AE41 AF01 3D044 AA25 AA47 AC26 AC57 AC59 AD04 AD17 AD21 AE04 AE07 AE18 AE22 AE27 3G093 AA05 AA07 AA16 BA15 BA23 DB05 DB16 DB18 EA09 EB03 EB04 FA03 FA05 3J052 AA04 BA14 BB17 EA04 EA05 GC46 GD05 HA01 KA01 LA01

Claims (5)

[Claims] 1. An inter-vehicle distance detecting means for detecting an inter-vehicle distance from a preceding vehicle, and an inter-vehicle distance control means for calculating a target vehicle speed for making a detected inter-vehicle distance detected by the inter-vehicle distance detecting means coincide with a target inter-vehicle distance. And self-vehicle speed detection means for detecting the self-vehicle speed; and a target braking / driving force for matching the own vehicle speed detection value detected by the own vehicle speed detection means with the target vehicle speed. Vehicle speed control means for controlling a rotary driving force source, a transmission and / or a braking device based on the vehicle speed; and road surface gradient detection means for detecting or estimating a downward gradient of a running road surface. Threshold setting means for setting a threshold for downshifting in accordance with the road surface downgrade detected or estimated by the means; and a deceleration force margin calculated based on the target braking / driving force and the downshifting threshold. The strange And a shift position determining means for determining a shift position of the speed unit. 2. The preceding vehicle according to claim 1, wherein said threshold value setting means is configured to set a shift-down threshold value so that a downshift becomes easier as the road surface gradient becomes larger. Tracking controller. 3. The threshold setting device according to claim 1, wherein the threshold setting unit sets the upshift threshold so that the upshift after downshifting becomes more difficult as the downhill gradient of the road surface becomes larger. Or the preceding vehicle following control device according to 2. 4. The road surface gradient detecting means includes a vehicle speed detected by the vehicle speed detecting means and a target control value calculated by a vehicle speed controlling means.
The preceding vehicle following control device according to any one of claims 1 to 3, wherein the controller is configured to estimate a road surface downhill gradient from a disturbance estimation value estimated based on the driving force. 5. The shift position determining means calculates a maximum deceleration force calculated based on a target vehicle speed calculated by the inter-vehicle distance control means from a required deceleration force value obtained based on the target braking / driving force. The preceding vehicle follow-up control device according to any one of claims 1 to 4, wherein the deceleration force margin is calculated by subtraction.