JP2003260956A - Control device for following preceding vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To eliminate the feeling of a physical disorder given to a driver when a desired inter-vehicle distance set value is changed from a small value to a large value when making an inter-vehicle distance accord with the desired inter-vehicle distance in controlling the vehicle of the driver to follow a preceding vehicle. <P>SOLUTION: A desired car speed V* is calculated by an inter-vehicle distance control section based on the inter-vehicle distance L detected by an inter-vehicle distance sensor and the car speed Vs of the driver's vehicle detected by a car speed sensor, and based on this desired car speed V*, the car speed is made to accord with a desired car speed by a car speed control section. At this moment, when the desired inter-vehicle distance set value is changed from a small value to a large value, the inter-vehicle distance is controlled smoothly by preventing the inter-vehicle distance from becoming short transitorily surely by restraining the reduction of a characteristic oscillation frequency ωT constituting at least feedback forward gain by the inter-vehicle distance control section. <P>COPYRIGHT: (C)2003,JPO

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 follows the vehicle while keeping a set inter-vehicle distance.

[0002]

2. Description of the Related Art As a conventional preceding vehicle following control device, for example, Japanese Patent Application Laid-Open No. 2000-35523 previously proposed by the present applicant.
The one described in Japanese Patent No. 5 is known. In this conventional example, the inter-vehicle distance control section calculates a target vehicle speed V ^* based on the inter-vehicle distance L detected by the inter-vehicle distance sensor and the own vehicle speed Vs detected by the vehicle speed sensor, and the vehicle speed control section is calculated based on the target vehicle speed. When performing the preceding vehicle follow-up control to match the own vehicle speed with the target vehicle speed, the inter-vehicle distance control unit uses the feed-forward compensator for calculating the inter-vehicle distance command value L _T based on the target inter-vehicle distance L ^*. Preceding vehicle follow-up control in which the inter-vehicle distance command value L _T is calculated by performing second-order lag type filter processing according to a reference model using the damping coefficient ζ and the natural frequency ω _n for the distance L. A device is disclosed. Here, the damping coefficient ζ and the natural frequency ω _n are damping values stored based on the inter-vehicle distance deviation, which is the deviation between the actual inter-vehicle distance L and the target inter-vehicle distance L ^* , and the relative speed with respect to the preceding vehicle. The calculation is performed by referring to the coefficient calculation map and the natural frequency calculation map.

[0003]

However, in the above-described conventional preceding vehicle follow-up control device, since the damping coefficient and the natural frequency in the inter-vehicle distance control system are selected in accordance with the required response characteristics, the driver Although the optimum follow-up control can be performed without giving a feeling of discomfort to the vehicle, normally, in order to perform the optimum follow-up vehicle follow-up control, a plurality of damping coefficient calculation maps and natural vibrations are calculated according to the target inter-vehicle distance. In addition to providing a number calculation map, a limiter that limits the rate of change of the target inter-vehicle distance is adopted for the purpose of obtaining gentle acceleration / deceleration control when the set value of the target inter-vehicle distance is significantly changed. It is conceivable to set the target inter-vehicle distance limit value restricted in step 1 as the target inter-vehicle distance. In this case, when the target inter-vehicle distance set value is changed from a short value to a long value, the corresponding damping coefficient calculation map and natural frequency calculation map are selected according to the set target inter-vehicle distance set value. However, the target inter-vehicle distance limit value output from the limiter will gradually increase, and even if the target inter-vehicle distance set value is changed, the inter-vehicle distance deviation remains small It is said that the damping coefficient ζ and the natural frequency ω _n that form the feedforward gain calculated based on the map and the natural frequency calculation map suddenly decrease, and the actual inter-vehicle distance tends to become shorter, which gives the driver a feeling of discomfort. There are unresolved issues.

Therefore, the present invention has been made by paying attention to the unsolved problem of the above-mentioned conventional example, and it is ensured that the inter-vehicle distance becomes short when the target inter-vehicle distance is changed from a short value to a long value. It is an object of the present invention to provide a preceding vehicle follow-up control device that prevents the driver from feeling uncomfortable.

[0005]

In order to achieve the above object, a preceding vehicle tracking control device according to a first aspect of the present invention is directed to a target inter-vehicle distance limit that limits a change amount of a target inter-vehicle distance set value for setting a target inter-vehicle distance. A target inter-vehicle distance setting means for calculating the value as the target inter-vehicle distance, the inter-vehicle distance detection value between the preceding vehicle detected by the inter-vehicle distance detecting means, and either the own vehicle speed or the preceding vehicle speed detected by the vehicle speed detecting means. An inter-vehicle distance control means for calculating a target vehicle speed that matches the inter-vehicle distance detection value with the target inter-vehicle distance calculated by the target inter-vehicle distance setting means, a target vehicle speed calculated by the inter-vehicle distance control means, and the own vehicle speed detected by the vehicle speed detection means. And a vehicle speed control means for controlling the vehicle speed to match the target vehicle speed control means, the target based on the feedforward gain provided in the inter-vehicle distance control means. Feedforward control means for performing feedforward control on the inter-vehicle distance, and determining the foot-forward gain based on at least the target inter-vehicle distance, and when the target inter-vehicle distance set value is changed from a short value to a long value, a predetermined value is set. And a feed-forward gain determining means for determining a feed-forward gain based on a target inter-vehicle distance shorter than the target inter-vehicle distance set value after the period change.

Further, the preceding vehicle following control device according to a second aspect of the present invention is, in the invention according to the first aspect, having a relative speed detecting means for detecting a relative speed with respect to the preceding vehicle, and the feedforward gain determining means. The feed-forward gain is set based on the target inter-vehicle distance, the inter-vehicle distance deviation between the target inter-vehicle distance and the inter-vehicle distance detection value, and the relative speed.

Further, in the preceding vehicle following control device according to a third aspect of the present invention, in the invention according to the second aspect, the feedforward gain determining means changes the target inter-vehicle distance set value from a short value to a long value. It is characterized in that the inter-vehicle distance deviation is held for a predetermined period as a deviation between the target inter-vehicle distance set value before the change and the inter-vehicle distance detection value. Furthermore,
The preceding vehicle following control device according to a fourth aspect is the invention according to the third aspect, wherein the feedforward gain determining means sets the inter-vehicle distance deviation when the target inter-vehicle distance matches the changed target inter-vehicle distance set value. It is characterized in that it is configured to return to the deviation between the target inter-vehicle distance and the inter-vehicle distance detection value.

Still further, in the preceding vehicle follow-up control device according to a fifth aspect of the present invention, in the invention according to the first aspect, the feedforward gain determining means changes the target inter-vehicle distance set value from a short value to a long value. In addition, it is characterized in that the feedforward gain determined based on the target inter-vehicle distance set value immediately before the change of the predetermined period is held.

Further, in the preceding vehicle following control device according to a sixth aspect of the present invention, in the invention according to the fifth aspect, the feedforward gain determining means determines when the target inter-vehicle distance matches the changed target inter-vehicle distance set value. Further, it is characterized in that the held feedforward gain is returned to the feedforward gain calculated based on the target inter-vehicle distance.

Further, in the preceding vehicle follow-up control device according to a seventh aspect of the present invention, in the invention according to the fifth aspect, the feedforward gain determining means determines when the target inter-vehicle distance matches the changed target inter-vehicle distance set value. In addition, when the held feedforward gain is restored to the feedforward gain calculated based on the changed target inter-vehicle distance, the held feedforward gain is gradually changed. .

Further, in the preceding vehicle following control device according to an eighth aspect of the present invention, in the invention according to any one of the first to seventh aspects, the target inter-vehicle distance setting means selects to select a plurality of different target inter-vehicle distance set values. And a change amount limiting unit that limits a change amount of the target inter-vehicle distance set value selected by the selecting unit.

[0012]

According to the preceding vehicle follow-up control device of the first aspect of the present invention, the feed-forward control is performed by the vehicle speed distance control system using the target inter-vehicle distance limit value in which the variation amount is limited with respect to the target inter-vehicle distance. The effect of being able to gently follow the target inter-vehicle distance in which the inter-vehicle distance detection value is changed can be obtained while suppressing the sudden decrease in the inter-vehicle distance by suppressing the sudden decrease of the feed-forward gain. .

According to the preceding vehicle following control device of the second aspect, the feedback gain is determined based on the target inter-vehicle distance, the inter-vehicle distance deviation between the target inter-vehicle distance and the inter-vehicle distance detection value, and the relative speed. Therefore, it is possible to smoothly follow the preceding vehicle without sudden deceleration when changing the target inter-vehicle distance. Further, according to the preceding vehicle following control device of the third aspect, when the target inter-vehicle distance is changed from a short value to a long value, the inter-vehicle distance deviation is changed to the target inter-vehicle distance whose rate of change is limited for a predetermined period. Instead, the target inter-vehicle distance set value before the change is applied, and the deviation between the target inter-vehicle distance set value and the inter-vehicle distance detection value is held, so that the inter-vehicle distance deviation corresponds to the actual inter-vehicle distance deviation, and the optimum The effect that the feedforward gain can be set can be obtained.

Further, according to the preceding vehicle following control device of the fourth aspect, when the target inter-vehicle distance whose change rate is limited matches the set target inter-vehicle distance, the change rate of the inter-vehicle distance deviation is limited. Since the deviation between the target inter-vehicle distance and the inter-vehicle distance detection value is restored, the feed-forward gain can be returned to the normal value without being discontinuous.

Further, according to the preceding vehicle following control device of the fifth aspect, when the target inter-vehicle distance is changed from a short value to a long value, it is determined based on the target inter-vehicle distance set value immediately before the change for the predetermined period. Since the set feedforward gain is held, it is possible to reliably prevent a sharp decrease in the feedforward gain immediately after the target inter-vehicle distance set value is changed.

Further, according to the preceding vehicle follow-up control device of the sixth aspect, when the target inter-vehicle distance whose change rate is limited matches the set target inter-vehicle distance set value, the held feedforward gain is changed. Is restored to the feedforward gain calculated on the basis of the reduced target inter-vehicle distance, so that the effect that the holding period of the feedforward gain can accurately correspond to the gain decreasing period is obtained.

Further, according to the preceding vehicle follow-up control device of the seventh aspect, when the feedforward gain is restored, the held feedforward gain is gradually changed, so that the gain can be changed gently. The effect is obtained. Furthermore, according to the preceding vehicle follow-up control device of the eighth aspect, the target inter-vehicle distance setting means selects the plurality of different target inter-vehicle distances, and the change amount of the target inter-vehicle distance selected by the selecting means. With the change amount limiting means for limiting the vehicle speed, it is possible to set the inter-vehicle distance according to the driver's preference.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic configuration diagram showing a first 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. , 1RR, the driving force of the engine 2 is the automatic transmission 3, the propeller shaft 4, the final reduction gear device 5.
And is transmitted via the axle 6 and is rotationally driven.

Front wheels 1FL, 1FR and rear wheels 1RL, 1R
Each R is provided with a disc brake 7 that generates a braking force, and the braking hydraulic pressure of these disc brakes 7 is controlled by a braking control device 8. Here, the braking control device 8 generates the braking hydraulic pressure in response to the depression of the brake pedal 8a, and the tracking control controller 2
It is configured to generate a braking hydraulic pressure according to the magnitude of the braking pressure command value P _BD supplied from 0 and supply it to the disc brake 7.

Further, the engine 2 is provided with an engine output control device 9 for controlling its output. The engine output control device 9 is configured to open and close the throttle valve 10a according to a throttle opening signal to change the intake air amount to the engine to control the throttle actuator 10 that adjusts the engine output. on the other hand,
An inter-vehicle distance sensor 12 including a radar device as an inter-vehicle distance detecting means for detecting an inter-vehicle distance L between the own vehicle and a preceding vehicle is provided on the lower part of the vehicle body on the front side of the vehicle.
The inter-vehicle distance sensor 12 may be, for example, a radar device that measures the inter-vehicle distance L between the preceding vehicle and the host vehicle by receiving a reflected light from the preceding vehicle by sweeping a laser beam forward, an electric wave, or an ultrasonic wave. A distance sensor that measures the inter-vehicle distance L can be applied.

Further, the vehicle is provided with a vehicle speed sensor 13 for detecting the own vehicle speed Vs by detecting the rotational speed of an output shaft arranged on the output side of the automatic transmission 3.
Furthermore, in the vicinity of the driver's seat, the inter-vehicle distance setting switch S that can set the inter-vehicle distance to the preceding vehicle in three stages of short distance LS, medium distance LM, and long distance LL at the driver's will.
W is provided.

The output signals of the inter-vehicle distance sensor 12 and the vehicle speed sensor 13 and the inter-vehicle distance selection signal of the inter-vehicle distance setting switch SW are input to the follow-up control controller 20. By controlling the braking control device 8 and the engine output control device 9 based on the inter-vehicle distance L detected in 1 and the vehicle speed Vs detected by the vehicle speed sensor 13, while maintaining an appropriate inter-vehicle distance with the preceding vehicle. Follow-up control is performed.

This follow-up control controller 20 comprises a microcomputer and its peripheral equipment, and constitutes the control block shown in FIG. 2 in the software form of the microcomputer. This control block measures the time from when the inter-vehicle distance sensor 1 sweeps a laser beam to when the reflected light of the preceding vehicle is received, and calculates a distance L between the preceding vehicle and a distance measurement signal processing unit 21, The vehicle speed signal processing unit 30 that measures the cycle of the vehicle speed pulse from the vehicle speed sensor 13 and calculates the own vehicle speed Vs, the inter-vehicle distance L calculated by the distance measurement signal processing unit 21, and the own vehicle speed calculated by the vehicle speed signal processing unit 30. Vs
The inter-vehicle distance control unit 40 as inter-vehicle distance control means for calculating the target vehicle speed V ^* for maintaining the inter-vehicle distance L at the target inter-vehicle distance L ^* , and the target vehicle speed V ^* and relative calculated by the inter-vehicle distance control unit 40. A vehicle speed control unit 50 is provided as a vehicle speed control unit that controls the throttle actuator 3, the automatic transmission T, and the braking device B based on the speed ΔV to control the own vehicle speed to match the target vehicle speed V ^* . .

The inter-vehicle distance control unit 40 includes the distance measurement signal processing unit 2
Relative to the preceding vehicle based on the inter-vehicle distance L input from 0
Relative speed calculation unit 41 for calculating speed ΔV and vehicle speed signal processing
Based on the vehicle speed Vs input from the processing unit 30,
Target inter-vehicle distance L with own vehicle ^*Target inter-vehicle distance to calculate
The relative speed calculated by the setting unit 42 and the relative speed calculation unit 41
Degree ΔV and the target vehicle calculated by the target inter-vehicle distance setting unit 42
Distance L^*Based on the damping coefficient ζ and the natural frequency ω_nTo
Feedforward compensator using the used reference model
The inter-vehicle distance L is set to the target inter-vehicle distance L^*To match
Inter-vehicle distance command value L_TFeedforward that computes
An inter-vehicle distance command value calculation unit 43 as control means, and this vehicle
Inter-vehicle distance command value L calculated by the inter-vehicle distance command value calculation unit 43
_TThe inter-vehicle distance L based on the inter-vehicle distance command value L_TMatched with
Target vehicle speed V to drive^*Target vehicle speed calculation unit 44 for calculating
And the relative speed ΔV calculated by the relative speed calculator 41, the target
Target vehicle speed L set by the inter-vehicle distance setting unit 42^*,Inter-vehicular distance
Inter-vehicle distance command value L calculated by the command value calculation unit 43_TAnd measurement
Based on the inter-vehicle distance L measured by the distance signal processing unit 21,
The damping coefficient ζ and the natural vibration used in the distance command value calculation unit 43
Ω_TAnd a control response determination unit 45 for determining
It

Here, the relative speed calculation unit 41 is composed of a bandpass filter for performing a bandpass filter process on the inter-vehicle distance L input from the distance measurement signal processing unit 20, for example. Since the transfer function of this bandpass filter can be expressed by the following equation (1) and the numerator has a differential term of the Laplace operator s, the inter-vehicle distance L is substantially differentiated to approximate the relative speed ΔV. Will be calculated.

F (s) = ω _C ² s / (s ² + 2ζ _C ω _C s + ω _C ² ) (1) where ω _C = 2πf _C , s is the Laplace operator, and ζ _C is the damping coefficient Is. As described above, by using the bandpass filter, as in the case of calculating the relative speed ΔV by performing a simple differential operation from the amount of change in the inter-vehicle distance L per unit time, it is vulnerable to noise and tracking control is being performed. It is possible to avoid that the vehicle behavior is likely to be affected, such as wobbling in the vehicle. 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 acceleration fluctuation before and after the vehicle body in a short cycle. Further, instead of using the bandpass filter, the relative speed ΔV may be calculated by differentiating the inter-vehicle distance L with a high-pass filter.

The target inter-vehicle distance setting section 42 also calculates the preceding vehicle speed Vt calculated by adding the relative speed ΔV to the own vehicle speed Vs.
(= Vs + ΔV) and the vehicle is behind the current preceding vehicle L
Time to reach the position of ₀ [m] T ₀ (inter-vehicle time)
From the following, the target inter-vehicle distance calculation unit 42 that calculates the target inter-vehicle distance set value L _SE between the preceding vehicle and the own vehicle according to the following equation (2)
a and a target inter-vehicle distance limiting section 42b configured by a limiter that limits the rate of change of the target inter-vehicle distance setting value L _SE calculated by the target inter-vehicle distance calculating section 42a. The target inter-vehicle distance L ^* whose rate is limited is output.

L _SE = Vt × T ₀ + L _S (2) In this equation (2), the concept of the inter-vehicle time T ₀ is introduced so that the inter-vehicle distance increases as the vehicle speed increases. To be done. Note that L _S is the inter-vehicle distance when the vehicle is stopped. Further, the inter-vehicle distance command value calculation unit 43 calculates the inter-vehicle distance command value L _T for following the vehicle while keeping the inter-vehicle distance L at the target value L ^* based on the inter-vehicle distance L and the target inter-vehicle distance L ^*. . Specifically, with respect to the input target inter-vehicle distance L ^* , the damping coefficient ζ and the natural frequency ω determined by the control response determination unit 45 for setting the response characteristic in the inter-vehicle distance control system as the target response characteristic. _The inter-vehicle distance command value L _T is calculated by performing the second-order lag type filter processing according to the reference model G _T (s) represented by the following equation (3) using _T.

[0029]

[Equation 1]

Further, the target vehicle speed calculating section 44 calculates the target vehicle speed V ^* by using the feedback compensator based on the input inter-vehicle distance command value L _T. In particular,
(4) below, as shown in the expression preceding vehicle from a vehicle speed Vt and the inter-vehicle distance command value L _T and a value of the deviation multiplied by (L _T -L) to a distance control gain fd and actual headway distance L, the relative speed ΔV The target vehicle speed V ^* is calculated by subtracting the linear combination with the value obtained by multiplying the speed control gain fv.

V ^* = Vt− {fd (L _T −L) + fv · ΔV} (4) Furthermore, the control response determination unit 45 is represented by a control block as shown in FIG. An inter-vehicle distance deviation calculation unit 45a that calculates an inter-vehicle distance deviation ΔL based on the inter-vehicle distance L, the target inter-vehicle distance set value L _SE and the target inter-vehicle distance L ^* , and Table 1 to be described later based on the target inter-vehicle distance set value L _SE . The map selection unit 45b for selecting the natural frequency calculation map of Table 3 and the damping coefficient calculation maps of Tables 4 to 6, and the map selection unit 45b based on the relative speed ΔV and the inter-vehicle distance deviation ΔL. A natural frequency calculation unit 45c that calculates a natural frequency ω _T by referring to a natural frequency calculation map, and a damping coefficient calculation selected by the map selection unit 45b based on the relative speed ΔV and the inter-vehicle distance deviation ΔL. Calculate the damping coefficient ζ by referring to the map It is composed of a damping coefficient calculation unit 45d for sending it to the inter-vehicle distance command value calculating section 43.

Here, the inter-vehicle distance deviation calculation unit 45a is
Time between vehicle distance L to target vehicle distance L ^*And subtract the vehicle distance
Separation deviation ΔL (= L−L^*) Is calculated, but as described later
And the target inter-vehicle distance set value L_SEChanges from short to long
Target before the change from the inter-vehicle distance L for a predetermined period
Inter-vehicle distance set value L_SEIs subtracted from the vehicle distance deviation ΔL (= L
-L_SE) Is calculated.

Further, the map selecting section 45b determines the target inter-vehicle distance.
Separation set value L_SEIs the first inter-vehicle distance threshold L_THL(Eg 2
0 m) and the second inter-vehicle distance threshold L_THH(Eg 40
m) compared to L_SE≤L_THLWhen the table below
1 and Table 4 for short range natural frequency calculation map and
And a damping coefficient calculation map are selected, and L_THL<L_SE<L
_THHAnd the solid for medium distance shown in Tables 2 and 5 below.
Select the frequency calculation map and damping coefficient calculation map
Then L_SE≧ L_THHTable 3 and Table₆Shown in
Map for calculation of natural frequency for long distance and calculation of damping coefficient
Select a map.

Specifically, with the assumption that the preceding vehicle is traveling at a constant speed, the following natural frequency ω _T is obtained so that the optimum response characteristic of the inter-vehicle distance control can be obtained in various following scenes. As shown in Tables 1 to 3, in accordance with the target inter-vehicle distance set value L _SE , the inter-vehicle distance deviation ΔL and the relative speed ΔV for short distance, medium distance and long distance, and the unique frequency of the inter-vehicle distance control system A natural frequency calculation map representing the relationship with ω _T is set. Similarly, as to the damping coefficient ζ, as shown in Tables 4 to 5 below, the inter-vehicle distance deviation ΔL and the relative speed ΔV for short distance, medium distance, and long distance are set according to the target inter-vehicle distance set value L _SE. Individual frequency of inter-vehicle distance control system ω
_An attenuation coefficient calculation map showing the relationship with _T is set.

Here, as shown in Tables 1 to 3, each natural frequency calculation map is x when the relative speed ΔV is “0” and the inter-vehicle distance deviation ΔL is “0”. It is scheduled in four quadrants, which are the axis and the y-axis.
Of these, the two quadrants in which the inter-vehicle distance deviation ΔL is negative are set so as to have a response characteristic that copes with the preceding vehicle interrupt, and the relative speed ΔV is included in the two quadrants in which the inter-vehicle distance deviation ΔL is positive.
The quadrant in which is negative is set so as to have a response characteristic that copes with the case where the preceding vehicle is distant and the vehicle approaches, and the remaining quadrants are used when the preceding vehicle is distant and moves away from the vehicle. The natural frequency ω _T is set so that the response characteristic to be dealt with is set, and the response characteristic that the actual inter-vehicle distance L slowly converges to the target inter-vehicle distance L ^* is obtained. Then, in an approaching scene or the like, the relative speed ΔV
It is preferable that the actual inter-vehicle distance L slowly converges to the target inter-vehicle distance L ^* without rapidly decelerating when the inter-vehicle distance is long even when is large. In such a follow-up scene, the actual inter-vehicle distance L has a quadratic response characteristic that converges after overshooting or undershooting the target inter-vehicle distance L ^*, and such a response has such a response that the filter of the formula (3) described above is used. Can be realized by The value of the natural frequency ω _T is set such that the short distance map has the largest value, and the natural frequency ω _T has the smaller value as it goes to the medium distance map and the long distance map.

[0036]

[Table 1]

[0037]

[Table 2]

[0038]

[Table 3]

Similarly to the natural frequency calculation map described above, the damping coefficient calculation map also shows the response characteristics of the inter-vehicle distance control until the actual inter-vehicle distance L reaches the target inter-vehicle distance L ^*. In order to obtain an optimum response characteristic according to ΔL and relative speed ΔV, as shown in Tables 4 to 6 below,
The inter-vehicle distance deviation ΔL, the relative speed ΔV, and the damping coefficient ζ are
When the relative speed ΔV is “0” and the inter-vehicle distance deviation ΔL
Are scheduled in four quadrants, where x is the x-axis and y is the y-axis. Also in this attenuation coefficient calculation map, the short distance map has the largest value, and the map is set to be slightly smaller as it goes to the medium distance map and the long distance map.

[0040]

[Table 4]

[0041]

[Table 5]

[0042]

[Table 6]

Then, the natural frequency calculator 45c uses the map selector 4 based on the relative speed ΔV and the inter-vehicle distance deviation ΔL.
The natural frequency ω _T for obtaining the optimum response characteristic is calculated with reference to the natural frequency calculation map selected in 5 b, and this is output to the inter-vehicle distance command value calculation unit 43. Further, the damping coefficient calculation unit 45d determines that the relative speed ΔV and the inter-vehicle distance deviation Δ
Based on L, the damping coefficient ζ for obtaining the optimum response characteristic is calculated by referring to the damping coefficient calculation map selected by the map selecting section 45b, and this is output to the inter-vehicle distance command value calculating section 43.

This inter-vehicle distance control system is represented by a block diagram as shown in FIG.
The target inter-vehicle distance L ^* calculated in 2 is used as the reference model GG.
It converted to inter-vehicle distance command value L _T feedforward compensator 46 in accordance with _T (s), to calculate the deviation of the actual inter-vehicle distance L between the inter-vehicle distance command value L _T by the subtractor 47, the deviation The feedback compensator 48 converts the target vehicle speed V ^* to control the vehicle C to be controlled.

In the follow-up control controller 5,
The inter-vehicle distance control process performed by the above-described inter-vehicle distance control system is executed according to the flowchart shown in FIG. This control process is executed as a timer interrupt process for the main program every predetermined time (for example, 10 msec). First, in step S1, the actual inter-vehicle distance L calculated by the distance measurement signal processing unit 21 and the vehicle speed signal processing unit 30. The vehicle speed Vs converted by is read, then the process proceeds to step S2, and the actual inter-vehicle distance L
Then, the relative speed ΔV is calculated by performing the bandpass filter process based on the equation (1), and the relative speed ΔV is updated and stored in the relative speed storage area, and then the process proceeds to step S3a.

In this step S3a, it is determined whether or not the inter-vehicle distance setting switch SW has been operated. If it has not been operated, the process directly proceeds to step S4a, and if it has been operated, the process proceeds to step S3b to set the inter-vehicle distance setting. Target inter-vehicle distance set value Li set by switch SW
After setting (i = LS, LM, LL) as the target inter-vehicle distance set value L _SE , the process proceeds to step S5 described later.

In step S4a, the relative vehicle speed Vs is added to the relative speed ΔV to calculate the preceding vehicle speed Vt (= Vs + ΔV), which is updated and stored in the preceding vehicle speed storage area, and then the process proceeds to step S4b. Vehicle speed Vt and time V
Based on ₀ , the equation (2) is calculated to calculate the target inter-vehicle distance setting value L _SE (n) this time, and then the process proceeds to step S5.

[0048] In step S5, the calculated current target inter-vehicle distance setting value L _SE (n) from one sampling period before the previous target inter-vehicle distance setting value L _SE (n-1) obtained by subtracting the amount of change ΔL
_SE (= L _SE (n) −L _SE (n-1)) is a preset limit value Δ
It is determined whether or not L _LIM or less, and when ΔL _SE ≦ ΔL _LIM , the process proceeds to step S6, and the current target inter-vehicle distance set value L _SE (n) is set to the target inter-vehicle distance L ^* (= L _SE ( n))
After setting as, the process proceeds to step S8, and ΔL _SE > Δ
When it is L _LIM , the process _proceeds to step S6, and a value obtained by adding the limit value ΔL _LIM to the previous target inter-vehicle distance set value L _SE (n-1) is the target inter-vehicle distance L ^* (= L _SE (n-1) + ΔL _LIM )
Then, the process proceeds to step S8.

In step S8, the response characteristic determining process shown in FIG. 6 described later is performed to calculate the natural frequency ω _T and the damping coefficient ζ which form the feedforward gain, and then the process proceeds to step S9. In this step S9, the natural frequency ω _n and the damping coefficient ζ stored in the natural frequency storage area and the damping coefficient storage area for the target inter-vehicle distance L ^* .
The cutoff frequency is set to 0.5 Hz, for example, and the inter-vehicle distance command value L _T is calculated by performing the above-described filter processing of the equation (3), and this is updated and stored in the inter-vehicle distance command value storage area. Then, the process proceeds to step S10, the equation (4) is calculated to calculate the target vehicle speed V ^* , and the target vehicle speed V ^* is sent to the vehicle speed control unit 50. Then, the timer interrupt process is terminated and a predetermined main program is executed. Return to.

The response characteristic determination process in step S8 is as follows.
As shown in FIG. 6, first, in step S11, it is determined whether or not the host vehicle recognizes the preceding vehicle. If the preceding vehicle is not recognized, the process ends and the process proceeds to step S9 in FIG. If the preceding vehicle is recognized, the process proceeds to step S12. In this step S12, the constant following threshold L _TH1 (for example, the absolute value (| L ^* -L |) of the value obtained by subtracting the inter-vehicle distance L from the target inter-vehicle distance L ^* calculated in step S6 or S7 is set to a small value (for example, 1m) or less, and if | L ^* -L |> _LTH1 , the process is terminated and the process proceeds to step S9 in FIG. 5, where | L ^* -L | _≤LTH1 . Sometimes step S1
Move to 3.

In this step S13, the target inter-vehicle distance set value L _SE calculated in step S4 is compared with the first inter-vehicle distance threshold L _THL and the second inter-vehicle distance threshold L _THH, and the short distance LS, the medium distance LM and The range of the long distance LL is set. Then, the process proceeds to step S14,
It is determined whether or not the holding flag FH holding the response characteristic is set to "1". If it is set to "1", the process jumps to step S26 described later,
When the holding flag FH is reset to "0", the process proceeds to step S15.

In step S15, the set range is set.
Is a long-distance LL, and the short-distance LS or medium
When it is the distance LM, the process proceeds to 22 which will be described later, and the long distance
When it is LL, the process proceeds to step S16. This
In step S16, the target vehicle one cycle before the previous one
Distance set value L _SEWhether the range of (n-1) is short distance LS
It is determined whether or not it is the medium distance LM or the long distance LL.
The process proceeds to step S22, which will be described later, and it is a short distance LS.
When it is decided that the short distance has been switched to the long distance LL
Then, the process proceeds to step S17.

In this step S17, the natural frequency calculation map of FIG. 3 and the damping coefficient calculation map of FIG. 6 corresponding to the long distance LL are selected, and then the process proceeds to step S18, where the inter-vehicle distance deviation ΔL is set as the target. Inter-vehicle distance set value L _SE
After setting the value obtained by subtracting the inter-vehicle distance L from step S
Move to 19. In this step S19, step S
The natural frequency ω _T is calculated based on the inter-vehicle distance deviation ΔL and the relative speed ΔV set in 18 with reference to the natural frequency calculation map of FIG. 3, and this is updated and stored in the natural frequency storage area. To step S20.

In this step S20, step S18
Based on the inter-vehicle distance deviation ΔL and the relative speed ΔV set in step 6, the damping coefficient ζ is calculated by referring to the damping coefficient calculation map in FIG. 6, and this is updated and stored in the damping coefficient storage area, and then the process proceeds to step S21. Then, the holding flag FH is set to "1", and then the process proceeds to step S26 described later. Further, in step S22, the natural frequency calculation map and the damping coefficient calculation map corresponding to the distance range set in step S13 are selected, the process proceeds to step S23, and the target calculated in step S6 or step S7 is selected. Inter-vehicle distance L ^* is subtracted from inter-vehicle distance L ^*
After calculating (= L ^* -L), the process proceeds to step S24.

In this step S24, step S23
Based on the inter-vehicle distance deviation ΔL and the relative speed ΔV set in step S22, the natural frequency ω _T is calculated with reference to the natural frequency calculation map selected in step S22, and this is updated and stored in the natural frequency storage area. Then, the process proceeds to step S25. In this step S25, step S22 is performed based on the inter-vehicle distance deviation ΔL and the relative speed ΔV set in step S23.
Refer to the damping coefficient calculation map selected in
Is calculated and updated and stored in the damping coefficient storage area, and then the process proceeds to step S25.

In step S26, step S6 or S
The target inter-vehicle distance L ^* calculated in 7 is the target inter-vehicle distance set value L
_It is determined whether or not _SE or more, and if L ^* <L _SE , the process is terminated and the process proceeds to step S9 in FIG. 5, and if L ^* ≧ L _SE , the process proceeds to step S27 and holds. After resetting the flag FH to "0", the process proceeds to step S9 in FIG.

In the process of FIG. 5, the process of step S2 corresponds to the relative speed calculating means, and steps S4 to S1 are performed.
The processing of 0 corresponds to the target inter-vehicle distance control means.
The processing of 4 to S7 corresponds to the target inter-vehicle distance calculating means, the processing of step S8 and the processing of FIG. 6 correspond to the feedforward gain determining means, and the processing of step S9 corresponds to the feedforward control means.

Further, the vehicle speed control unit 50 calculates the driving force command value F _OR and the estimated disturbance value d _V ′ for matching the own vehicle speed Vs with the input target vehicle speed V ^* , and the target consisting of these deviations is calculated. It is composed of a vehicle speed servo system for calculating the braking / driving force F ^*.
As disclosed in Japanese Patent No. 72963, a vehicle speed servo system or a general feedback control system based on a robust model matching control method composed of a model matching compensator and a robust compensator can be applied.

The eyes output from the vehicle speed controller 50
Regulation / driving force F^*Based on the braking control device 8 and engine
The vehicle output control device 9 is controlled so that the inter-vehicle distance L becomes equal to the target inter-vehicle distance.
Distance L ^*Follow-up control is performed so as to match with. Next, the above
The operation of the first embodiment will be described. Now the vehicle recognizes the preceding vehicle
Knowing this, it will follow this preceding vehicle in the range of short distance LS, for example.
I'm going.

Under this condition, the absolute value | L ^* -L | of the vehicle-to-vehicle distance deviation obtained by subtracting the vehicle-to-vehicle distance L detected by the vehicle-to-vehicle distance sensor 12 from the target vehicle-to-vehicle distance L ^* is a constant vehicle-to-vehicle distance such that the vehicle-to-vehicle distance threshold L _TH1 or less. Assuming that the vehicle is in the following traveling state, the relative vehicle speed ΔV and the preceding vehicle speed Vt are calculated in the processing of FIG. 5, and the target inter-vehicle distance set value L _SE is calculated based on these. At this time, for example, assuming that the preceding vehicle is traveling at a constant speed, the target inter-vehicle distance set value L _SE maintains a constant value at a relatively short distance as shown in FIG. The target inter-vehicle distance L ^* obtained by limiting the value L _SE in steps S5 to S7 also maintains a constant value that is substantially equal to the target inter-vehicle distance set value L _SE , as shown in FIG. 7B.

In this state, in the response characteristic processing of FIG. 6, since the preceding vehicle is recognized and the vehicle is traveling at a constant inter-vehicle distance, the process proceeds to step S13 through steps S11 and S12, and the target inter-vehicle distance set value L _{SE is} set. Is relatively short, so short range LS
Is set as. At this time, since the inter-vehicle distance range is not changed, the holding flag FH is reset to "0", the process proceeds from step 14 to S15, and the inter-vehicle distance range is LS. Therefore, the process proceeds to step S22 and the inter-vehicle distance range is performed. Natural frequency calculation map of Table 1 according to LS and Table 4
The attenuation coefficient calculation map of is selected.

Then, in step S23, the inter-vehicle distance deviation
ΔL is calculated, but the target inter-vehicle distance L ^*And the following distance L
Since they are almost equal, it is common that the inter-vehicle distance deviation ΔL becomes “0”.
Then, the relative speed ΔV also becomes “0”, which is displayed in step S24.
Natural frequency when referring to 1 natural frequency calculation map
Number ω_TAs shown in Fig. 7 (d), 0.131 is calculated as
Then, in step S25, the attenuation coefficient calculation map of Table 4 is
When referred to, 0.800 is calculated as the damping coefficient ζ.
It

By using the natural frequency ω _T and the damping coefficient ζ to perform the filtering process in step S9 of FIG. 5, the inter-vehicle distance command value L for maintaining the current following traveling state.
_T is calculated, the braking pressure of the inter-vehicle distance command value the target vehicle speed to maintain the current vehicle speed Vs based on L _T V ^* is calculated to maintain the current non-braking state by the vehicle speed control unit 50 to "0" The command value P _BD is output to the braking control device 8 and the throttle opening command value θ for maintaining the current throttle opening
Is output to the engine output control device 9.

Therefore, the inter-vehicle distance L detected by the inter-vehicle distance sensor 12 is also controlled to a value substantially equal to the target inter-vehicle distance set value L _SE and the target inter-vehicle distance L ^* as shown in FIG. Continue driving. When the following traveling state in the short distance range LS is continued and the driver operates the inter-vehicle distance setting switch SW at time t1 to select the long distance LL,
The target inter-vehicle distance set value L _SE is immediately changed to a value corresponding to the long distance LL as shown in FIG. 7 (a). However, even if the target inter-vehicle distance setting value L _SE is changed from the short distance LS to the long distance LL, the target inter-vehicle distance L ^* is the current target distance L s (n-1) against the previous target inter-vehicle distance setting value L _SE (n-1). Since the inter-vehicle distance set value L _SE (n) is larger than the limit value ΔL _{LIM, the process proceeds} from step S5 to step S7, and the change amount of the target inter-vehicle distance L ^* is limited to ΔL _LIM . For this reason,
The target inter-vehicle distance L ^* gradually increases as shown in FIG. 7 (b).

Thus, the inter-vehicle distance range changes from the short distance LS to
When the distance is changed to the long distance LL, the response characteristic calculation process of FIG.
Then, through steps S15 and S16, the process proceeds to step S17.
For calculating natural frequency of Table 3 corresponding to long distance LL
When the map is selected, the map for calculating the damping coefficient in Fig. 6 is displayed.
Selected. On the other hand, as the inter-vehicle distance deviation ΔL,
Target inter-vehicle distance L whose rate of increase is limited in step S18
^*Instead of the target inter-vehicle distance of the newly set long distance LL
Set value L _SEIs applied and the deviation between this and the actual inter-vehicle distance L
Since it is calculated as a difference, this inter-vehicle distance deviation ΔL is -2.
Since it exceeds 0 m, the relative velocity ΔV hardly changes.
Therefore, in step S19, the natural frequency calculation map in Table 3 is calculated.
The natural frequency ω_TAs 0.111
It is calculated and this is updated and stored in the natural frequency storage area.
It Therefore, the natural frequency ω_TAs shown in Fig. 7 (d)
Then, it is decreased from 0.131 to 0.111. Also reduced
For the damping coefficient ζ, also refer to the map for calculating the damping coefficient in Table 6.
0.950 is calculated when this is done, and this is the damping coefficient memory
It is updated and stored in the area. Then, move to step S21
Then, the holding flag FH is set to "1".

Therefore, in the next sampling cycle,
Since the holding flag FH is set to "1",
In the response characteristic determination process of FIG. 6, from step S14
Directly jump to step S26 to store the natural frequency
And the natural frequency ω stored in the damping coefficient storage area_T
And the damping coefficient ζ are held, and the target inter-vehicle distance L ^*
Is the target inter-vehicle distance set value L as shown in FIG._SEReached
Since it is not done, the holding flag FH maintains the state of "1".
To do.

Therefore, the inter-vehicle distance calculated in step S9
Distance command value L_TIs the target inter-vehicle distance L ^*Is the limit value
ΔL_LIMNatural frequency ω_TThe value of is
Target inter-vehicle distance L^*And the inter-vehicle distance L are approximately "0"
Calculated based on inter-vehicle distance deviation and relative speed ΔV of "0"
Natural frequency ω_TLarger than (= 0.086)
Value, the previous inter-vehicle distance command value L_T(n-
It will increase with respect to 1). Therefore, the vehicle speed control
The throttle opening command value θ calculated by the unit 50 decreases,
Throttle actuator 1 with engine output control device 9
0 is controlled to close the throttle valve 10a,
Apply engine braking to generate deceleration and decelerate
If the degree is insufficient, the braking pressure command value P_BDBraking control device 8
To the disc brake 7 to generate braking force and reduce it.
Speed up. As a result, the vehicle detected by the inter-vehicle distance sensor 12
The inter-distance L gradually increases as shown in FIG. 7 (c).

After that, at the time point t2, when the target inter-vehicle distance L ^* whose increase rate is limited reaches the target inter-vehicle distance set value L _SE , the response characteristic determining process of FIG. 6 proceeds from step S26 to step S27. Since the holding flag FH is reset to "0", the process proceeds from step S14 to step S15 in the next sampling cycle, and the long distance LL is set, so the process proceeds to step S16, but the previous long distance LL is also performed. Therefore, the process proceeds to step S22, and the natural frequency calculation of FIG. 3 is performed based on the vehicle-to-vehicle distance deviation ΔL between the target vehicle-to-vehicle distance L ^* and the vehicle-to-vehicle distance L whose increase rate is limited, and the relative speed ΔV. Natural frequency ω
_T is calculated. As a result, the natural frequency ω _T is shown in FIG.
As shown in (d), when the vehicle is in the following traveling state in which it gradually decreases according to the inter-vehicle distance deviation ΔL and maintains the long distance LL,
The natural frequency ω _T is maintained after about 0.086, and the inter-vehicle distance L is also set to the target inter-vehicle distance set value L _SE as shown in FIG. 7C.
It will be in a state substantially matching with.

As described above, according to the first embodiment, even when the target inter-vehicle distance set value is changed from the short distance LS to the long distance LL, the natural frequency ω _T constituting the feedforward gain is rapidly reduced. Since the inter-vehicle distance L is controlled to be gradually increased and controlled toward the gradually changed long distance LL without being shortened, smooth inter-vehicle distance increase control can be performed without giving a discomfort to the driver. You can

By the way, the target inter-vehicle distance set value is the short distance LS.
When the distance is changed from the long distance LL to the long distance LL, the difference between the target inter-vehicle distance L ^* and the inter-vehicle distance L whose increase rate is limited as the inter-vehicle distance deviation ΔL is set as in the normal following traveling state. When the target inter-vehicle distance set value L _SE is changed from a short value to a long value at time t1 of 7, since the increase amount of the target inter-vehicle distance L ^* is small, the inter-vehicle distance deviation ΔL becomes a value close to “0”, Since the relative velocity ΔV is also substantially “0”, when referring to the natural frequency calculation map in Table 3, the natural frequency ω
_T is set to 0.086 as shown by the chain double-dashed line in FIG. 7 (d). Further, the damping coefficient ζ becomes 0.760 when the damping coefficient calculation map in Table 6 is referred to, and is 0.8
It is slightly reduced from 00.

In this way, the natural frequency ω _T is rapidly reduced from 0.131 to 0.086, so that step S9 in FIG.
The inter-vehicle distance command value L _T calculated in step S1 becomes shorter than the previous value, and the vehicle speed control unit 50 increases the throttle opening command value θ accordingly. In c), it decreases once and then increases as shown by the chain double-dashed line. For this reason, the driver feels uncomfortable because the inter-vehicle distance is temporarily shortened even though the inter-vehicle distance L is set to be long. However, in the first embodiment, it is possible to reliably prevent the inter-vehicle distance from becoming short when the target inter-vehicle distance set value L _SE is changed from a short value to a long value, and perform smooth inter-vehicle distance control.

Next, a second embodiment of the present invention will be described with reference to FIGS. In the second embodiment, when the target inter-vehicle distance L _SE is changed from a short value to a long value, the natural frequency ω _T and the damping coefficient ζ before the change are held for a predetermined period, so that the inter-vehicle distance is temporarily changed. This is to prevent it from becoming shorter. That is, in the second embodiment, as shown in FIG. 8 in the response characteristic determination process, steps S17 to S20 are omitted in the process of FIG. 6 in the above-described first embodiment, and instead of this, step S1.
When it is determined in 6 that the previous distance range is the short distance LS, the process proceeds to step S31, and the natural frequency ω _T (n-1) and the damping coefficient ζ (n-1) one sampling period before are set. Set the natural frequency ω _T (n) and damping coefficient ζ (n) this time,
The same processing as in FIG. 6 is performed except that the processing is updated and stored in the natural frequency storage area and the damping coefficient storage area and then the process proceeds to step S21.
The processes corresponding to those in FIG. 6 are denoted by the same step numbers, and detailed description thereof will be omitted.

According to the second embodiment, when the preceding vehicle is recognized and the vehicle is following with the short distance LS while keeping the inter-vehicle distance L substantially constant, as shown in FIG. 9A, at time t1. When the inter-vehicle distance setting switch SW is operated to set the target inter-vehicle distance set value L _SE to the long distance LL, the process proceeds from step S16 to step S31 in the response characteristic determination process of FIG. Natural frequency ω _T (n-1) with inter-vehicle distance deviation ΔL = 0 and relative speed ΔV = 0 calculated with reference to the natural frequency calculation map corresponding to 1 short distance LS
(= 0.131) is set as the natural frequency ω _T (n) of this time, and the damping coefficient ζ is also set to the previous damping coefficient ζ (n-1).
By setting (= 0.800) as the damping coefficient ζ (n) of this time, the natural frequency ω _T and the damping coefficient ζ are held at the previous values before the change of the target inter-vehicle distance set value L _SE . Therefore, as shown in FIG. 9D, the natural frequency ω _T is maintained at a large value without decreasing. Therefore, the natural frequency ω _T and the damping coefficient ζ are used as the feedforward gain to perform the inter-vehicle distance filtering. By calculating the distance command value L _T , the target inter-vehicle distance L ^* becomes longer by the limit value ΔL _LIM, so that the inter-vehicle distance command value L _T gradually becomes longer than before the change.

As a result, the inter-vehicle distance L smoothly increases without being shortened as shown in FIG. 9C, and the same effect as that of the first embodiment can be obtained. After that, when the target inter-vehicle distance L ^* reaches the target inter-vehicle distance set value L _SE at time t2, the process proceeds from step S26 to step S27 in the response characteristic determination process of FIG. 6, and the holding flag FH is reset to “0”. As a result, the process proceeds from step S16 to step S22, and the natural frequency calculation map of Table 3 and the damping coefficient calculation map of Table 6 are selected according to the target inter-vehicle distance set value L _SE of the long distance LL. At this time, based on the inter-vehicle distance deviation ΔL between the target inter-vehicle distance L ^* and the inter-vehicle distance L and the relative speed ΔV, referring to the natural frequency calculation map of Table 3 and the damping coefficient calculation map of Table 6, the natural vibration The number ω _T and the damping coefficient ζ are calculated. At this time,
Since the vehicle-to-vehicle distance deviation ΔL is about −20 m, the natural frequency ω _T is 0.110 and the damping coefficient ζ is 0.950. Therefore, the natural frequency ω _T is changed from the value 0.131 held until the last time to 0.110,
The amount of decrease becomes approximately the same as when the target inter-vehicle distance set value is changed in the first embodiment, it is possible to prevent the inter-vehicle distance L from decreasing, and it is possible to continue smooth inter-vehicle distance control.

Next, a third embodiment of the present invention will be described with reference to FIGS. In the third embodiment, when the holding state of the feedforward gain in the second embodiment is released, the natural frequency ω _T and the damping coefficient ζ are gradually decreased. That is, in the third embodiment, as shown in FIG. 10, the response characteristic determination process includes step S41 before step S22 in the process of FIG. 8 in the second embodiment described above. It is determined whether or not the release flag FC representing the release state of the gain holding state is set to "1", and when it is reset to "0", the process proceeds to step S42 and the previous holding flag FH Is set to "1", and if it is reset to "0", the above step S
If it is set to "1", the process proceeds to step S43.

In this step S43, the release flag FC
Is set to "1", then the process proceeds to step S44, and the value obtained by subtracting the predetermined reduction amount Δω from the previous natural frequency ω _T (n-1) is set as the current natural frequency ω _T (n). At the same time, the value obtained by subtracting the predetermined reduction amount Δζ from the previous damping coefficient ζ (n-1) is set as the current damping coefficient ζ (n), and then the process proceeds to step S45.

In this step S45,
22 to S25, the natural frequency calculation map and the damping coefficient calculation map according to the current distance range are selected, and the target inter-vehicle distance L ^* and the inter-vehicle distance L are selected.
The inter-vehicle distance deviation ΔL is calculated, and the calculated inter-vehicle distance deviation Δ
The normal natural frequency ω _TN and the damping coefficient ζ _N are calculated with reference to the natural frequency calculating map and the damping coefficient calculating map selected based on L and the relative speed ΔV, and then the step S
Move to 46.

In this step S46, step S44
It is determined whether or not the natural frequency ω _T (n) calculated in step S45 is less than or equal to the natural frequency ω _TN calculated in step S45.
_{When T} (n)> ω _TN , the process proceeds to step S47, the natural frequency ω _T (n) is set as the natural frequency ω _T , and this is updated and stored in the natural frequency storage area before the processing. Upon completion, the process proceeds to step S9 in FIG. 5, where ω _T (n) ≤ω
_If it is _TN , the process proceeds to step S48, the natural frequency ω _TN is set as the natural frequency ω _T , the natural frequency ω _TN is updated and stored in the natural frequency storage area, then the process proceeds to step S49, and the release flag FC is set to " After resetting to "0", the process is terminated and the process proceeds to step S9 in FIG.

According to the third embodiment, the preceding vehicle is recognized, and the following distance is set to the long distance by operating the following distance setting switch SW while the following vehicle is traveling at a short distance LS at a substantially constant following distance. When LL is set as the target inter-vehicle distance set value L _SE, as shown in FIG. 11, the natural frequency ω _T and the damping coefficient ζ before the change are held as in the second embodiment described above.

After that, at the time t2 when the target inter-vehicle distance L ^* reaches the target inter-vehicle distance set value L _SE , when the holding flag FH is reset to "0", the response characteristic determining process of FIG. Since the release flag FC has been reset to "0" at S41, the process proceeds to step S42. Since the previous holding flag FH was "1", the process proceeds to step S43 and the release flag FC is set. After setting to "1", the process proceeds to step S44, and the value obtained by subtracting the predetermined reduction amount Δω from the previous natural frequency ω _T (n-1) is set as the current natural frequency ω _T (n). At the same time, a value obtained by subtracting the predetermined reduction amount Δζ from the previous damping coefficient ζ (n-1) is set as the current damping coefficient ζ (n).

As a result, as shown in FIG. 11 (d), the natural frequency ω _T is gradually reduced by limiting the reduction amount by the predetermined reduction amount Δω, and at this time, the release flag FC is "1".
Is set to. Therefore, the process of reducing the natural frequency ω _T and the damping coefficient ζ is continued. After that, the natural frequency ω _T (n) decreased at the time point t3 calculates the inter-vehicle distance deviation ΔL of the target inter-vehicle distance L ^* and the inter-vehicle distance L, and selects based on the calculated inter-vehicle distance deviation ΔL and relative speed ΔV. Normal natural frequency ω _TN calculated by referring to natural frequency calculation map
When, the normal natural frequency ω _TN becomes the natural frequency ω _T
Is set as and is updated and stored in the natural frequency storage area, and the release flag FC is reset to “0”. Thereafter, the process proceeds to step S22 through steps S41 and S42, and the normal natural frequency ω _TN and The process returns to the setting process of the damping coefficient ζ _N.

Therefore, according to the third embodiment, when the target inter-vehicle distance L ^* whose rate of change is limited reaches the target inter-vehicle distance set value L _SE , the natural frequency ω _T and the damping coefficient ζ.
Is gradually reduced, the inter-vehicle distance L can be changed more gently than in the second embodiment described above, and the driver's discomfort can be more reliably reduced. .

In the third embodiment, the case where the natural frequency ω _T and the damping coefficient ζ are gradually reduced when the feedforward gain holding state in the second embodiment is released will be described. However,
The present invention is not limited to this, and the natural frequency ω _T and the damping coefficient ζ may be gradually decreased at the time point t1 in the above-described first embodiment.

Further, in the first to third embodiments, the case where both the natural frequency ω _T and the damping coefficient ζ are reduced is explained, but the natural frequency ω _T has more influence on the feedforward gain. Therefore, only the natural frequency ω _T may be reduced, and the value referred to in the map may be used as it is as the damping coefficient ζ.
Further, in the first to third embodiments, the case where the target inter-vehicle distance setting unit 42 calculates the target inter-vehicle distance set value L _SE based on the preceding vehicle speed Vt has been described, but the present invention is not limited to this. Alternatively, the own vehicle speed Vs may be applied instead of the preceding vehicle speed Vt, and the target inter-vehicle distance set value L _SE may be calculated based on this, and further, the target inter-vehicle distance set value L _SE may be calculated. The target inter-vehicle distance set values LS, LM, L set by the inter-vehicle distance setting switch SW are omitted.
You may make it use only L.

Furthermore, in the first to third embodiments described above, the feedforward compensator 4 is used as the feedforward control system of the inter-vehicle distance control system as shown in FIG.
Although the case where the feedforward control system is composed of only 6 is described, the feedforward control system is not limited to this, and the feedforward control system includes the feedforward compensator 46 and the phase compensator 49, as shown in FIG. 49, below (5)
The compensating vehicle speed command value V _FF may be calculated by performing the filtering process shown in the equation and added to the output V _FB of the feedback compensator 48. In this case, the actual inter-vehicle distance is long. The degree of decrease in relative speed can be moderated, and smooth follow-up traveling control can be performed.

[0086]

[Equation 2]

Here, ω _V is the corner frequency of the transfer characteristic of the vehicle speed control section. Furthermore, in the above-described first to third embodiments, the case where the natural frequency and the damping coefficient are calculated using the natural frequency calculating storage table and the damping coefficient calculating storage table has been described. It is needless to say that it is not limited and may be calculated from a characteristic equation.

In the first to third embodiments described above, the case where the follow-up control controller 5 executes the inter-vehicle distance calculation processing has been described. However, the present invention is not limited to this, and the function generator, comparison It may be configured by applying hardware that is an electronic circuit that is configured by combining a calculator, an arithmetic unit, and the like. Further, in the above embodiment, the case where the present invention is applied to the rear-wheel drive vehicle has been described, but the present invention can also be applied to the front-wheel drive vehicle, and the case where the engine 2 is applied as the rotary drive source will be described. However, the present invention is not limited to this, and an electric motor can be applied, and further, the present invention can be applied to a hybrid vehicle using an engine and an electric motor.

[Brief description of drawings]

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

FIG. 2 is a block diagram showing a specific configuration of the follow-up control controller of FIG.

FIG. 3 is a block diagram showing a specific example of a control response determination unit in FIG.

FIG. 4 is a block diagram showing a schematic configuration of an inter-vehicle distance control system.

FIG. 5 is a flowchart showing an example of inter-vehicle distance control processing in an inter-vehicle distance control unit.

6 is a flowchart showing an example of the response characteristic determination process of FIG.

FIG. 7 is a time chart used for explaining the operation of the first embodiment.

FIG. 8 is a flowchart showing an example of response characteristic determination processing according to the second embodiment of the present invention.

FIG. 9 is a time chart used for explaining the operation of the second embodiment.

FIG. 10 is a flowchart showing an example of response characteristic determination processing according to the third embodiment of the present invention.

FIG. 11 is a time chart for explaining the operation of the third embodiment.

FIG. 12 is a block diagram showing another example of a feedforward control system applicable to the present invention.

[Explanation of symbols]

2 engine 3 automatic transmission 7 disc brakes 8 Braking control device 9 Engine output control device 10 Throttle actuator 12 inter-vehicle distance sensor 13 vehicle speed sensor 40 Inter-vehicle distance control unit 41 Relative speed calculator 42 Target inter-vehicle distance setting section 42a Target distance calculation unit 42b Target inter-vehicle distance limiter 43 Inter-vehicle distance command value calculation unit 44 Target vehicle speed calculator 45 Control response determination unit 45a Inter-vehicle distance deviation calculation unit 45b Map selection section 45c Natural frequency calculator 45d Attenuation coefficient calculator 50 vehicle speed controller

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) B60R 21/00 627 B60R 21/00 627 F02D 29/02 301 F02D 29/02 301D G08G 1/16 G08G 1 / 16 EF Term (Reference) 3D044 AA25 AB01 AC26 AC59 AD04 AD21 AE01 AE04 AE14 AE18 AE19 AE22 3G093 BA23 CB10 DB05 DB16 EA09 EB04 EC01 EC04 FA02 FA05 FA07 FA10 FA11 FA12 FB05 5H180 AA01 CC14 LL09

Claims (8)

[Claims] 1. A target inter-vehicle distance setting means for calculating a target inter-vehicle distance limit value that sets a target inter-vehicle distance setting value as a target inter-vehicle distance limit value, and a preceding vehicle detected by the inter-vehicle distance detection means. A target vehicle speed that matches the detected inter-vehicle distance with the target inter-vehicle distance calculated by the target inter-vehicle distance setting means is calculated based on the inter-vehicle distance detected value and the vehicle speed detected by the vehicle speed detection means or the preceding vehicle speed. A preceding vehicle follow-up control device comprising: an inter-vehicle distance control means; and a vehicle speed control means for controlling the speed so that the target vehicle speed calculated by the inter-vehicle distance control means and the own vehicle speed detected by the vehicle speed detection means are matched. Feed-forward control means for performing feed-forward control on the target inter-vehicle distance based on the feed-forward gain provided in the inter-vehicle distance control means, and at least The foot-forward gain is determined based on the target inter-vehicle distance, and when the target inter-vehicle distance set value is changed from a short value to a long value, a target inter-vehicle distance shorter than the target inter-vehicle distance set value after a predetermined period is changed. And a feedforward gain determining means for determining a feedforward gain based on the preceding vehicle tracking control device. 2. A relative speed detecting means for detecting a relative speed with respect to a preceding vehicle, wherein the feedforward gain determining means has a target inter-vehicle distance, an inter-vehicle distance deviation between the target inter-vehicle distance and an inter-vehicle distance detection value, and a relative value. The preceding vehicle following control device according to claim 1, wherein the feedforward gain is set based on a speed. 3. The feedforward gain determining means detects the target inter-vehicle distance set value and the inter-vehicle distance before the change of the inter-vehicle distance deviation for a predetermined period when the target inter-vehicle distance set value is changed from a short value to a long value. 3. The preceding vehicle tracking control device according to claim 2, characterized in that the deviation from the value is held. 4. The feedforward gain determining means restores the inter-vehicle distance deviation to the deviation between the target inter-vehicle distance and the inter-vehicle distance detection value when the target inter-vehicle distance matches the changed target inter-vehicle distance set value. The preceding vehicle follow-up control device according to claim 3, which is configured. 5. The feedforward gain determining means determines, when the target inter-vehicle distance set value is changed from a short value to a long value, the feed forward gain determined based on the target inter-vehicle distance set value immediately before the predetermined period is changed. The preceding vehicle following control device according to claim 1, wherein the preceding vehicle following control device is configured to hold. 6. The feedforward gain determining means calculates a held feedforward gain based on the target inter-vehicle distance when the target inter-vehicle distance matches the changed target inter-vehicle distance set value. The preceding vehicle tracking control device according to claim 5, wherein the preceding vehicle tracking control device is configured to return to a gain. 7. The feedforward gain determining means calculates the held feedforward gain based on the changed target inter-vehicle distance when the target inter-vehicle distance matches the changed target inter-vehicle distance set value. The preceding vehicle tracking control device according to claim 5, wherein the retained feedforward gain is configured to be gradually changed when returning to the feedforward gain. 8. The target inter-vehicle distance setting means selects a plurality of different target inter-vehicle distance setting values, and a change amount limiting means for limiting a change amount of the target inter-vehicle distance setting value selected by the selecting means. The preceding vehicle following control device according to any one of claims 1 to 7, characterized in that: