JPH10272963A - Leading vehicle follow-up control device - Google Patents

Abstract

(57) [Problem] To converge to a target inter-vehicle distance with a simple configuration so that relative speed does not become excessively large or small. SOLUTION: The target vehicle speed is calculated in a form including a linear combination of a value obtained by multiplying a deviation between a detected value of an inter-vehicle distance and a target inter-vehicle distance by a first gain and a value obtained by multiplying a detected value of a relative speed by a second gain. Calculating and driving device such that the detected value of own vehicle speed becomes the target vehicle speed,
Control the transmission and braking device. As a result, the target vehicle speed can be calculated in consideration of the relative speed with respect to the preceding vehicle, and the inter-vehicle distance can be made to converge to the target value without the relative speed in the following process becoming excessively large or small. In addition, it can be realized with a simple control system configuration, the number of tuning steps can be reduced, and the tuning result is not affected by individual differences among coordinators.

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 preceding vehicle while maintaining a constant inter-vehicle distance.

[0002]

2. Description of the Related Art A vehicle speed V, a deviation ΔR between a detected inter-vehicle distance and a target inter-vehicle distance, a gain Gv which is a function of the vehicle speed V,
Based on a gain Gr that is a function of the inter-vehicle distance deviation ΔR and a gain Gd that is a function of the relative speed ΔV, a target vehicle speed is calculated so that the inter-vehicle distance keeps the target inter-vehicle distance. Is known (for example, see Japanese Patent Application Laid-Open No. 6-227280).

[0003]

However, since the conventional preceding vehicle follow-up control device is basically a control system for converging the inter-vehicle distance to the target inter-vehicle distance, the relative speed is inevitably reached when the target inter-vehicle distance is reached. However, the relative speed may become too large or too small in the process up to that point.

[0004] Further, in the conventional preceding vehicle follow-up control device, the target vehicle speed is calculated using a plurality of gains, so that there is the following problem. (1) Since each gain is set empirically, tuning man-hours are required, and it differs depending on the preference of the coordinator and individual differences in ability. (2) Since each gain is stored in the form of an arithmetic expression, a table, or the like, the storage capacity of the memory is increased and the load of the arithmetic processing of the microcomputer is increased. (3) Since this is a non-linear control system in which the gain Gd relating to the relative speed ΔV and the inter-vehicle distance deviation ΔR are incorporated in the form of a product, there is no guarantee that good convergence is obtained for all following traveling conditions.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a preceding vehicle follow-up control device which has a simple configuration and converges to a target inter-vehicle distance so that the relative speed does not become too large or too small.

[0006]

[Means for Solving the Problems]

(1) The invention according to claim 1 is a vehicle speed detecting means for detecting a vehicle speed, an inter-vehicle distance detecting means for detecting an inter-vehicle distance, and a vehicle speed for calculating a target vehicle speed for making the inter-vehicle distance detection value a target inter-vehicle distance. The present invention is applied to a preceding-vehicle follow-up control device including a calculation unit and a vehicle speed control unit that controls a driving device, a transmission, and a braking device so that a detected value of the vehicle speed becomes a target vehicle speed. And a relative speed detecting means for detecting a relative speed between the preceding vehicle and the own vehicle, wherein the vehicle speed calculating means multiplies a value obtained by multiplying a deviation between the detected value of the following distance and the target following distance by a first gain; The target vehicle speed is calculated in a form including a linear combination with the value obtained by multiplying the value by the second gain. (2) The preceding vehicle following control device according to claim 2 calculates the preceding vehicle speed by adding the relative speed to the own vehicle speed detection value by the vehicle speed calculating means, and calculates the deviation between the inter-vehicle distance detection value and the target inter-vehicle distance. The target relative speed is calculated by adding the value obtained by multiplying the first gain and the value obtained by multiplying the detected relative speed value by the second gain, and the target vehicle speed is calculated by subtracting the target relative speed from the preceding vehicle speed. It was made. (3) The preceding vehicle following control device according to claim 3 approximates the vehicle speed control system of the vehicle speed control means with a linear transfer function, and based on the transfer characteristics, the detected inter-vehicle distance becomes the target inter-vehicle distance, and the relative speed detected value becomes The first gain and the second gain are set so that the convergence characteristics that converge to 0 become arbitrary characteristics. (4) The preceding vehicle following control device according to claim 4 is such that the relative speed detecting means detects the relative speed by applying a band-pass filter or a high-pass filter to the inter-vehicle distance detection value. (5) The preceding vehicle following control device according to claim 5 sets the target inter-vehicle distance according to the preceding vehicle speed. (6) The preceding vehicle following control device according to claim 6 sets the target inter-vehicle distance in accordance with the own vehicle speed.

[0007]

【The invention's effect】

(1) According to the first aspect of the present invention, the linear difference between the value obtained by multiplying the deviation between the detected inter-vehicle distance and the target inter-vehicle distance by the first gain and the value obtained by multiplying the detected relative speed by the second gain. The target vehicle speed is calculated in a form including the coupling, and the driving device, the transmission, and the braking device are controlled so that the detected vehicle speed becomes the target vehicle speed. It can be calculated, and the inter-vehicle distance can be made to converge to the target value without the relative speed in the following process becoming excessively large or small. In addition, it can be realized with a simple control system configuration, the number of tuning steps can be reduced, and the tuning result is not affected by individual differences among coordinators. (2) According to the second aspect of the present invention, the preceding vehicle speed is calculated by adding the relative speed to the own vehicle speed detection value, and the deviation between the inter-vehicle distance detection value and the target inter-vehicle distance is multiplied by the first gain. The target relative speed is calculated by adding the value and the value obtained by multiplying the detected relative speed value by the second gain, and the target vehicle speed is calculated by subtracting the target relative speed from the preceding vehicle speed. The same effect can be obtained. (3) According to the third aspect of the invention, the vehicle speed control system is approximated by a linear transfer function, and the detected inter-vehicle distance is converged to the target inter-vehicle distance and the detected relative speed is converged to 0 based on the transfer characteristics. Since the first gain and the second gain are set so that the characteristics become arbitrary characteristics, the convergence characteristics intended by the designer can be easily obtained. (4) According to the invention of claim 4, the relative speed is detected by applying a band-pass filter or a high-pass filter to the inter-vehicle distance detection value.
Compared to the method of calculating the relative speed by performing a simple differential calculation based on the amount of change in the inter-vehicle distance detection value per unit time, the influence of noise is less and the vehicle behavior during tracking control may be affected. Absent. (5) According to the fifth aspect of the present invention, the target inter-vehicle distance is set according to the preceding vehicle speed, so that the optimal target inter-vehicle distance can be set. (6) According to the invention of claim 6, since the target inter-vehicle distance is set according to the own vehicle speed, the preceding inter-vehicle speed is calculated based on the own vehicle speed and the relative speed to set the target inter-vehicle distance. Compared with the method, it is less likely to be affected by noise superimposed on the relative speed, and an optimal target inter-vehicle distance can be set.

[0008]

FIG. 1 is a diagram showing the configuration of an embodiment. The inter-vehicle distance sensor head 1 is a radar-type sensor head that sweeps laser light and receives reflected light from a preceding vehicle. The inter-vehicle distance may be measured using radio waves or ultrasonic waves. The vehicle speed sensor 2 is attached to the output shaft of the transmission, and outputs a pulse train having a cycle according to the rotation speed. The throttle actuator 3 opens and closes a throttle valve according to a throttle opening signal,
Adjust the engine output by changing the intake air volume of the engine. The automatic transmission 4 changes the gear ratio according to the vehicle speed and the throttle opening. The braking device 6 is a device that generates a braking force on the vehicle.

The follow-up controller 5 includes a microcomputer and peripheral components, determines a target vehicle speed based on the detected distance between the vehicles and the detected vehicle speed, and controls the throttle actuator 3, the automatic transmission 4, and the braking device 6.

The follow-up controller 5 constitutes control blocks 11, 21, 50 and 51 shown in FIG. 2 in the form of software of a microcomputer. The ranging signal processing unit 11 measures the time from when the laser beam is scanned by the inter-vehicle distance sensor head 1 to when the reflected light of the preceding vehicle is received, and calculates the inter-vehicle distance with the preceding vehicle. When there are a plurality of preceding vehicles ahead, the preceding vehicle to be followed is specified and the inter-vehicle distance is calculated. The vehicle speed signal processing unit 21 measures the period of the vehicle speed pulse from the vehicle speed sensor 2 and detects the speed of the host vehicle.

The preceding vehicle following control unit 50 includes a relative speed calculation unit 501, an inter-vehicle distance control unit 502, and a target inter-vehicle distance setting unit 503. Based on the inter-vehicle distance L and the own vehicle speed V, the target inter-vehicle distance L ^* Calculate the vehicle speed V ^* . The relative speed calculation unit 501 calculates a relative speed ΔV with respect to the preceding vehicle based on the inter-vehicle distance L detected by the distance measurement signal processing unit 11.
The inter-vehicle distance control unit 502 calculates a target vehicle speed V ^* for matching the inter-vehicle distance L with the target inter-vehicle distance L ^* in consideration of the relative speed ΔV. The target inter-vehicle distance setting unit 503 sets a target inter-vehicle distance L ^* according to the vehicle speed Vt of the preceding vehicle or the own vehicle speed V.

The vehicle speed control unit 51 also controls the throttle opening of the throttle actuator 3, the gear ratio of the automatic transmission 4, and the braking device 6 so that the vehicle speed V becomes the target vehicle speed V ^*.
To control the braking force.

FIG. 3 is a diagram showing a detailed configuration of the vehicle speed control unit 51. The vehicle speed servo unit 531 controls the throttle servo unit 532 by calculating a target throttle opening degree Tvo ^* for matching the vehicle speed V with the target vehicle speed V ^* , and controls the automatic transmission 4 by calculating a shift command. I do. Further, the braking device 6 is controlled by calculating a required braking force. The throttle servo unit 532 drives and controls the throttle actuator 3 based on the target throttle opening Tvo ^* .

FIG. 4 is a diagram showing a detailed configuration of the vehicle speed servo section 531 and the throttle servo section 532. The throttle servo unit 532 drives and controls the throttle actuator 3 based on the target throttle opening Tvo ^* . In this embodiment, a PI control method is used to match the actual throttle opening Tvo with the target throttle opening Tvo ^* . Here, the target performance of the throttle servo system is determined according to the target performance of the vehicle speed servo system which is a higher rank. For example, in the vehicle speed servo system, the overshoot and the undershoot of the vehicle speed V are ± 1 with respect to the road gradient change of ± 6%.
If it is necessary to control the throttle servo system to be equal to or less than km / h, the throttle servo system must be capable of following up to 1 Hz.

The vehicle speed servo unit 531 is designed by a "robust model matching control method" in this embodiment in order to make the servo system resistant to disturbances such as road gradient fluctuations.

FIG. 5 is a diagram showing a detailed configuration of the vehicle speed servo unit 531. The robust model matching control system of the vehicle speed servo unit 531 includes a robust compensator and a model matching compensator. The robust compensator is a so-called disturbance compensator, and it is possible to configure a control system that matches actual characteristics to the linear model GV (s) by estimating and correcting disturbances such as modeling errors and running resistance of a controlled object. it can. H (s) is a robust filter that determines the disturbance rejection performance of the robust compensator.
It consists of a low-pass filter of c. At this time, if the cut-off frequency is increased, the disturbance rejection performance is improved. To determine.

The model matching compensator is a compensator for matching the response characteristics of the vehicle speed servo system to the reference model.
Input / output response characteristics are determined by the reference model R2 (s) of the feedforward section, and the reference model R2 of the feedback section is determined.
1 (s) determines the disturbance elimination performance and stability. By designing the vehicle speed servo system with the robust model matching control method in this way, the responsiveness of following the model error, parameter fluctuations, disturbances, etc. with the characteristics of the reference model and the internal variables quickly without diverging The convergence stability can be secured.

Next, a method of calculating the relative speed ΔV with respect to the preceding vehicle will be described. The relative speed ΔV is calculated based on the following distance L detected by the following distance sensor head 1 and the distance measurement signal processing unit 11, as shown in FIG. In the conventional preceding vehicle follow-up control device, as shown in the following equation, the relative speed ΔV is calculated by performing a simple differential calculation based on the amount of change in the inter-vehicle distance L per unit time.

ΔV = {L (t) −L (t−Δt)} / Δt

However, this calculation method is susceptible to noise and tends to affect the vehicle behavior, such as wobble during tracking control. Therefore, in this embodiment, a method is used in which the inter-vehicle distance L is input and the relative speed ΔV is approximately obtained by passing through the band-pass filter or the high-pass filter. For example, a bandpass filter is represented by a transfer function shown in the following equation.

F (s) = ωc ² s / (s ² + 2ζωcs + ωc ² ), where ωc = 2πfc and s is a Laplace operator. As is clear from Equation 2, the numerator of the transfer function of the band-pass filter has a differential term of the Laplace operator s.
And the relative speed Δ
V will be calculated. Similarly, by applying a high-pass filter to the inter-vehicle distance L, the relative speed ΔV can be approximately obtained. Note that the cutoff frequency fc in Expression 2 is determined by the magnitude of the noise component included in the inter-vehicle distance L and the allowable value of the short-period G fluctuation before and after the vehicle body.

Next, a control law for maintaining the target inter-vehicle distance and following the preceding vehicle will be described. As shown in FIG. 2, the basic configuration of the control system includes a preceding vehicle following control unit 50 and a vehicle speed control unit 51 separately. The output of the preceding vehicle following control unit 50 is the target vehicle speed V ^* , and the inter-vehicle distance L is not directly controlled.

The following distance control unit 5 of the preceding vehicle following control unit 50
02 calculates a target vehicle speed V ^* for following the vehicle while keeping the inter-vehicle distance L at its target value L ^* based on the inter-vehicle distance L, the target inter-vehicle distance L ^*, and the relative speed ΔV. Specifically, as shown in FIG. 8, 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 gain fd (first gain), and a relative speed ΔV The target relative speed ΔV ^* is obtained by a configuration including a linear combination with a value multiplied by a gain fv (second gain), and the target vehicle speed V ^* is calculated by further subtracting the target relative speed ΔV ^* from the preceding vehicle speed Vt.

ΔV ^* = fd (L ^* −L) + fv · ΔV

## EQU4 ## V ^* = Vt-.DELTA.V ^*

The control gains fd and fv are parameters that determine the following control performance. Since this system is a one-input, two-output system that controls two target values (inter-vehicle distance and relative speed) with one input (target vehicle speed), the control system is designed using a state feedback (regulator) control method. . Hereinafter, the procedure of control system design will be described.

The state variables x1 and x2 of the system are defined by the following equations.

X1 = Vt-V

X2 = L ^* -L The control input (output of the controller) is defined as V ^* and is defined by the following equation.

[Equation 7] V ^* = Vt-ΔV ^* vehicle-to-vehicle distance L is given by the following equation.

L = ∫ (Vt−V) dt + L0, where L0 is an initial value of the inter-vehicle distance L.

The vehicle speed servo system can be approximately expressed by a linear transfer function in which the actual vehicle speed V has a first-order delay with respect to the target vehicle speed V ^* , as shown in the following equation.

V = V ^* / (1 + τv · s)

## EQU10 ## Assuming that the preceding vehicle speed Vt is constant, dV / dt = (V ^* -V) /. Tau.
According to Equation 10,

Dx1 / dt = (− 1 / τv) x1 + (1 / τv) ΔV ^* Further, assuming that the target inter-vehicle distance L ^* is constant, Equations 6 and 8 give:

Dx2 / dt =-(Vt-V) =-x1 Therefore, the state equation of the system can be described as follows.

(Equation 13)

The control input u is given by the following equation.

U = FX, F = [fv fd] The state equation of the entire system to which the state feedback is applied is as follows.

(Equation 15) Here, if A '= A + BF,

(Equation 16) Therefore, the characteristic equation of the whole system is derived as follows.

[Equation 17]

As described above, the vehicle speed servo system can be approximately expressed by a linear transfer function. Based on the transfer characteristics, the convergence characteristics are set such that the inter-vehicle distance L converges to the target value L ^* and the relative speed ΔV converges to 0. The gains fd and fv are set so as to obtain the characteristics intended by the user. For example, the time constant of the vehicle speed servo system is τv = 0.5 [sec], and the pole (target value) of the preceding vehicle following control system is 0.14 ± 0.14j (ωn =
(0.2, ζ = 0.7) is as follows.

S ² + 2ζωns + ωn ² = s ² +0.28 s +
0.04 = 0 According to Expression 17 and Expression 18,

(1−fv) /τv=2-2fv=0.28

Fd / τv = 2fd = 0.04 Therefore, the gains fd and fv are

[Mathematical formula-see original document] fv = 0.86, fd = 0.02

In this embodiment, as shown in FIG.
Since the relative speed ΔV is the speed difference between the preceding vehicle and the own vehicle,
The preceding vehicle speed Vt is calculated using the own vehicle speed V and the relative speed ΔV obtained from the inter-vehicle distance data.

Vt = V + ΔV Therefore, the target vehicle speed V ^{* in} this case is given by Equations (3) and (4).
And from equation 22:

V ^* = V−fd (L ^* −L) + (1−fv) ΔV Further, in order to prevent rapid acceleration and deceleration, the target vehicle speed V
^* Limit the amount of change per unit time.

On the other hand, the target inter-vehicle distance L ^* may be set by using the concept of inter-vehicle time used for approach warning or the like, but here, from the viewpoint of not affecting the convergence of control at all, the target inter-vehicle distance L ^* is not affected. This is a function of vehicle speed. Formula 22
Using the vehicle speed of the preceding vehicle defined in

L ^* = a.Vt + Lof, where a is a coefficient and Lof is an offset.

[0029] When computing the vehicle speed Vt of the preceding vehicle based on the vehicle speed V and the relative speed [Delta] V, so influenced by the noise superimposed on the relative speed [Delta] V, the target inter-vehicle distance L ^* as shown in FIG. 10 own This is a function of the vehicle speed V. For example, the target inter-vehicle distance L ^* is set by the following equation.

## EQU25 ## L ^* = a.V + Lof

FIGS. 11 to 15 show simulation results of the embodiment. In each figure, the solid line of the vehicle speed data V indicates the own vehicle speed V, the broken line indicates the target vehicle speed V ^* , the solid line of the following distance data L indicates the following distance L, and the broken line indicates the target following distance L.
^{Indicates *} . The solid line of the relative speed data ΔV indicates the actual relative speed, and the broken line indicates the value calculated by the band-pass filter. Data Accel indicates the vehicle acceleration.

The conditions of the simulation are as follows: (1) The vehicle speed is 100 km / h, the following distance is 40 m,
m when the vehicle is interrupted by a vehicle with a vehicle speed of 80 km / h, (2) similarly, when the vehicle is interrupted by a vehicle with a vehicle speed of 100 km / h, (3) at a speed of 60 km / h while traveling at a speed of 100 km / h. In three scenes in which a running vehicle is captured, a case where the target inter-vehicle distance L ^* is a function of the preceding vehicle speed Vt (Equation 24) and a case where it is a function of the own vehicle speed V (Equation 25) were performed. Further, the pole of the system is -0.17 ± 0.10j, and the feedback gain fv =
0.87 and fd = 0.02.

11 and 12 show the case where the target inter-vehicle distance L ^* is a function of the preceding vehicle speed Vt. FIG. 11 shows the simulation condition (1), and FIG. 12 shows the simulation condition (2).
The case of is shown. 13 to 15 show the target inter-vehicle distance L.
^* With the case as a function of its own vehicle speed V, the 13 simulation condition (1), FIG. 14 is the simulation condition (2), FIG. 15 shows the case of a simulation conditions (3).

In the case of the simulation condition (1), that is, when the vehicle is interrupted by a vehicle having a vehicle speed of 80 km / h 20 m ahead while following the vehicle at a vehicle speed of 100 km / h and an inter-vehicle distance of 40 m, FIGS. As described above, the change in the relative speed ΔV at the time of the interruption is almost only by the vehicle speed difference of 20 km / h between the original preceding vehicle and the interruption vehicle.
The vehicle is approaching the target inter-vehicle distance L ^* (approximately 32 m) corresponding to the preceding vehicle speed Vt or the own vehicle speed V while sufficiently suppressing the change in V. In the case of the simulation condition (2),
That is, if the vehicle is interrupted by a vehicle having a vehicle speed of 100 km / h 20 m ahead while following the vehicle at a vehicle speed of 100 km / h and an inter-vehicle distance of 40 m, the change in the relative speed ΔV is suppressed as shown in FIGS. The target inter-vehicle distance L ^* (4
0m).

In the configuration of the above-described embodiment, the vehicle speed sensor 2 and the vehicle speed signal processing section 21 correspond to the own vehicle speed detecting means, the inter-vehicle distance sensor head 1 and the ranging signal processing section 11 correspond to the inter-vehicle distance detecting means, The control unit 50 forms a vehicle speed calculation unit, the vehicle speed control unit 51 forms a vehicle speed control unit, and the relative speed calculation unit 501 forms a relative speed detection unit.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of an embodiment.

FIG. 2 is a control block diagram of a tracking control controller.

FIG. 3 is a diagram showing a detailed configuration of a vehicle speed control unit.

FIG. 4 is a diagram showing a detailed configuration of a vehicle speed servo unit and a throttle servo unit.

FIG. 5 is a diagram showing a detailed configuration of a vehicle speed servo unit.

FIG. 6 is a diagram illustrating a method of calculating a relative speed.

FIG. 7 is a diagram illustrating a method of calculating a relative speed.

FIG. 8 is a diagram illustrating a method of calculating a target vehicle speed.

FIG. 9 is a diagram illustrating a method of calculating a target vehicle speed.

FIG. 10 is a diagram illustrating a method of calculating a target inter-vehicle distance.

FIG. 11 is a diagram showing a simulation result of one embodiment.

FIG. 12 is a diagram showing a simulation result of one embodiment.

FIG. 13 is a diagram showing a simulation result of one embodiment.

FIG. 14 is a diagram showing a simulation result of one embodiment.

FIG. 15 is a diagram showing a simulation result of one embodiment.

[Explanation of symbols]

 Reference Signs List 1 inter-vehicle distance sensor head 2 vehicle speed sensor 3 throttle actuator 4 automatic transmission 5 following control controller 6 braking device 11 distance signal processing unit 21 vehicle speed signal processing unit 50 preceding vehicle following control unit 51 vehicle speed control unit 501 relative speed calculation unit 502 inter-vehicle distance Control unit 503 Target inter-vehicle distance setting unit 531 Vehicle speed servo unit 532 Throttle servo unit

Claims (6)

[Claims] A vehicle speed detecting means for detecting a vehicle speed, an inter-vehicle distance detecting means for detecting an inter-vehicle distance, a vehicle speed calculating means for calculating a target vehicle speed for setting a detected inter-vehicle distance as a target inter-vehicle distance; A vehicle speed control means for controlling a drive device, a transmission, and a braking device such that a vehicle speed detection value becomes a target vehicle speed; a relative speed detection means for detecting a relative speed between the preceding vehicle and the own vehicle; Wherein the vehicle speed calculation means includes a linear combination of a value obtained by multiplying a deviation between the detected inter-vehicle distance and the target inter-vehicle distance by a first gain, and a value obtained by multiplying a detected relative speed value by a second gain. A preceding vehicle following control device, which calculates a target vehicle speed in a form. 2. The preceding vehicle following control device according to claim 1, wherein the vehicle speed calculating means calculates a preceding vehicle speed by adding a relative speed to the own vehicle speed detection value, and calculates a preceding vehicle speed and a target inter-vehicle distance. The target relative speed is calculated by adding the value obtained by multiplying the deviation from the distance by the first gain and the value obtained by multiplying the relative speed detection value by the second gain, and subtracting the target relative speed from the preceding vehicle speed to obtain the target relative speed. A preceding vehicle following control device, which calculates a vehicle speed. 3. The preceding vehicle following control device according to claim 1, wherein the vehicle speed control system of the vehicle speed control means is approximated by a linear transfer function, and the inter-vehicle distance detection value is set to a target value based on the transfer characteristic. A preceding vehicle follow-up control device, wherein the first gain and the second gain are set such that convergence characteristics in which a relative speed detection value converges to 0 with respect to an inter-vehicle distance become arbitrary characteristics. 4. The preceding vehicle following control device according to claim 1, wherein the relative speed detecting means determines a relative speed by applying a band-pass filter or a high-pass filter to the inter-vehicle distance detection value. A preceding vehicle following control device characterized by detecting. 5. The preceding vehicle following control device according to claim 1, wherein the target following distance is set according to the preceding vehicle speed. 6. The preceding vehicle following control device according to claim 1, wherein the target following distance is set according to the own vehicle speed.