JPH1159222A - Preceding car following control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a response characteristic most suitable for all running environments. SOLUTION: This control device calculates a target car speed V* to make a detected inter-vehicle distance value L be a target inter-vehicle distance value L* by changing a first gain fd and a second gain fv according to the detected inter-vehicle distance value L and based on the value obtained by multiplying the deviation ΔL of the inter-vehicle distance value L from the target inter- vehicle distance value L* by the first gain fd and the value obtained by multiplying a relative speed calculation value ΔV by the second gain fv. Then, vehicle control drive force is controlled so that an own-car speed detection value V becomes a target car speed V*. This constitution provides a follow-up control response characteristic most suitable for all running environments such as approaching a preceding car from a long way and being cut in by other car during follow-up control.

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, an inter-vehicle distance deviation .DELTA.L, a gain GV which is a function of the inter-vehicle distance V, a gain GR which is a function of an inter-vehicle distance deviation .DELTA.L, and a gain GD which is a function of a relative speed .DELTA.V. Then, the following formula is used to calculate a target vehicle speed VT such that the following distance keeps the target following distance.

(Equation 1) A preceding vehicle following control device that controls the vehicle speed so as to attain the target vehicle speed VT is known (for example, Japanese Patent Application Laid-Open No. 6-227).
280).

[0003]

However, in the conventional preceding vehicle follow-up control device, since various gains GV, GR, and GD are set empirically, it is possible to obtain an optimum response characteristic in any traveling environment. There is a problem that is difficult.

[0004] It is an object of the present invention to provide a preceding vehicle follow-up control device capable of obtaining an optimum response characteristic in any traveling environment.

[0005]

[Means for Solving the Problems]

(1) The invention of claim 1 is an inter-vehicle distance detecting means for detecting an inter-vehicle distance, a relative speed calculating means for calculating a relative speed between the preceding vehicle and the own vehicle based on the inter-vehicle distance detection value, and an inter-vehicle distance detected value Target vehicle speed for obtaining a detected inter-vehicle distance as a target inter-vehicle distance based on a value obtained by multiplying a deviation between the target speed and a target inter-vehicle distance by a first gain and a value obtained by multiplying a calculated relative speed value by a second gain. , A gain changing means for changing the first gain and the second gain in accordance with the inter-vehicle distance detection value, a vehicle speed detection means for detecting the own vehicle speed, and a self-vehicle speed detection value for the target vehicle speed. Vehicle speed control means for controlling the braking / driving force of the vehicle. (2) The preceding vehicle following control device according to claim 2, wherein the gain changing means decreases the first gain and increases the second gain when the inter-vehicle distance detection value is long and reduces the inter-vehicle distance detection value. Is such that the first gain is increased and the second gain is decreased. (3) The preceding vehicle following control device according to claim 3 constructs a preceding vehicle following control system by approximating the vehicle speed control system with a linear transfer function,
Set the detected inter-vehicle distance to the target inter-vehicle distance and set the relative speed calculation value to 0.
The first gain and the second gain are set such that the convergence characteristics for converging to the respective values become arbitrary characteristics. (4) The preceding vehicle following control device sets the first gain and the second gain by giving the natural frequency of the transfer function of the preceding vehicle following control system as a function of the inter-vehicle distance detection value. It is like that.

[0006]

【The invention's effect】

(1) According to the first aspect of the present invention, the first gain and the second gain are changed according to the inter-vehicle distance detection value, and the deviation between the inter-vehicle distance detection value and the target inter-vehicle distance is multiplied by the first gain. A target vehicle speed for calculating the detected inter-vehicle distance as the target inter-vehicle distance is calculated based on the calculated value and the value obtained by multiplying the calculated relative speed by the second gain. Then, since the braking / driving force of the vehicle is controlled so that the detected value of the own vehicle speed becomes the target vehicle speed, when the vehicle approaches the preceding vehicle from a distance or is interrupted by another vehicle during the following control, the An optimum response characteristic of the following control with respect to the traveling environment can be obtained. (2) According to the second aspect of the invention, when the inter-vehicle distance detection value is long, the first gain is decreased and the second gain is increased, and when the inter-vehicle distance detection value is short, the first gain is increased. As a result, the second gain is reduced, so that when the vehicle approaches the preceding vehicle from a distance, the response characteristics are set to be slow. As a result, it is possible to start deceleration immediately after capturing the preceding vehicle and slowly converge to the target inter-vehicle distance,
The deceleration of the vehicle is small and the impact on the occupants is small. In addition, when the vehicle is interrupted by another vehicle while following the vehicle, a fast response characteristic is set. As a result, deceleration is started immediately after the interruption, and the vehicle can immediately converge to the target inter-vehicle distance without excessively approaching the preceding vehicle. (3) According to the third and fourth aspects of the present invention, the preceding vehicle following control system is constructed by approximating the vehicle speed control system with a linear transfer function, and the detected inter-vehicle distance is converted to the target inter-vehicle distance, and the relative speed calculation value is calculated. Are set so that the convergence characteristics for converging to 0 each become an arbitrary characteristic, so that the intended convergence characteristics can be obtained. (4) According to the invention of claim 4, the first gain and the second gain are set by giving the natural frequency of the transfer function of the preceding vehicle following control system as a function of the inter-vehicle distance detection value. Therefore, the intended convergence characteristics can be obtained by a simple method.

[0007]

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, calculates a target vehicle speed based on the detected inter-vehicle distance and vehicle speed, and controls the throttle actuator 3, the automatic transmission 4, and the braking device 6.

The follow-up controller 5 comprises control blocks 11, 21, 50 and 51 shown in FIG. 2 in the form of microcomputer software. The ranging signal processing unit 11 measures the time from when the inter-vehicle distance sensor head 1 sweeps the laser beam to when the reflected light of the preceding vehicle is received, and calculates the inter-vehicle distance L to 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 cycle of the vehicle speed pulse from the vehicle speed sensor 2 and detects the speed V of the own vehicle.

The preceding vehicle following control unit 50 includes a relative speed calculating 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 making the inter-vehicle distance L equal to 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 shows the configuration of the entire control system. First, a target vehicle speed V * for following the vehicle while maintaining the inter-vehicle distance L at the target value L * is calculated. As shown in FIG. 3, the target relative speed ΔV * is determined by the sum of a value obtained by multiplying the deviation fL between the target inter-vehicle distance L * and the inter-vehicle distance L by the gain fd and a value obtained by multiplying the relative speed ΔV by the gain fv. Ask. Note that the gain fd
Corresponds to the above-described first gain, and the gain fv corresponds to the above-described second gain.

(Equation 2) The gains fd and fv are parameters that determine the tracking control performance. Next, the target vehicle speed V * is obtained by subtracting the target relative speed ΔV * from the preceding vehicle speed VT.

(Equation 3) Also, the inter-vehicle distance detection value L is converted to a bandpass filter BPS.
To determine the relative speed ΔV, and further calculate the preceding vehicle speed VT.

(Equation 4) Therefore, the target vehicle speed V * is expressed as follows by Expressions 2, 3 and 4.

(Equation 5)

Next, an inter-vehicle distance control system will be described.
This system sets two target values, ie, inter-vehicle distance and relative speed, as 1
Since it is a one-input, two-output system controlled by two inputs (target vehicle speed), a control system is designed using state feedback (regulator). The system state variables are x1, x2
Is defined by the following equation.

(Equation 6) In Equation 6, VT is the vehicle speed of the preceding vehicle, and V is the own vehicle speed.

(Equation 7) The control input (output of the controller) is defined by the following equation as V *.

(Equation 8) The following distance L is represented by the following equation.

(Equation 9) In Expression 9, Lo is an initial value of the inter-vehicle distance.

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

(Equation 10) Assuming that the preceding vehicle speed VT is constant, Equations 6, 8, and 10 give:

[Equation 11] Further, assuming that the target inter-vehicle distance L * = constant, Equations 7 and 9 give

(Equation 12) Therefore, the state equation of the system can be described as:

(Equation 13)

The control input u is given by the following equation.

[Equation 14] The state equation of the entire system to which the state feedback has been applied is represented by the following equation.

(Equation 15)

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

[Equation 17] Based on the transmission characteristics of the vehicle speed servo system described above, the following distance L
The gain f is set so that the characteristic in which the relative velocity ΔV converges to 0 becomes the characteristic intended by the designer.
Set d and fv.

(Equation 18)

[Equation 19]

(Equation 20)

The convergence characteristic of the follow-up control system to which the state feedback is applied is approximated by a secondary system as represented by Expression 17. For example, the time constant τv = 0.
When the poles of the system are set to a pole having a slow convergence characteristic and a pole having a fast convergence characteristic by the pole arrangement method, each gain f
d and fv are obtained from Expressions 19 and 20, respectively, as follows. Double root: -0.1 (ωn = 0.2, ζ = 1.0) → fd =
0.02, fv = 0.8 Double root: -0.4 (ωn = 0.4, ζ = 1.0) → fd =
0.08, fv = 0.6

FIGS. 4 and 5 show simulation results of the system when approaching a preceding vehicle at a relative speed of 20 km / s at a distance of 120 m. FIG. 4 shows the case of the gain setting, and FIG. 5 shows the case of the gain setting. In these figures,
(A) shows own vehicle speed V and target vehicle speed V *, (b) shows inter-vehicle distance L and target inter-vehicle distance L *, and (c) shows relative speed Δ.
V and the relative speed estimated value ΔVs, and (d) shows the acceleration / deceleration of the vehicle. When approaching the preceding vehicle, the control is started from a point at which the inter-vehicle distance is long with a slow pole setting, and slowly converges to the target inter-vehicle distance. The deceleration of the vehicle at this time is about 0.5 m / ss at the maximum. On the other hand, in the fast pole setting, control starts after the inter-vehicle distance is reduced to some extent,
The deceleration of the vehicle is about 1m /
ss, which is larger than the slow pole case.

FIGS. 6 and 7 show 100 km / h and an inter-vehicle distance of 4 km.
FIG. 6 shows a simulation result of a system in a case where a vehicle having a relative speed of 15 km / h is interrupted by a vehicle having a relative speed of 15 km / h while following at 0 m, and FIG. 6 shows a case of a gain setting and FIG. In these figures,
(A) shows own vehicle speed V and target vehicle speed V *, (b) shows inter-vehicle distance L and target inter-vehicle distance L *, and (c) shows relative speed Δ.
V and the relative speed estimated value ΔVs, and (d) shows the acceleration / deceleration of the vehicle. As shown in FIG. 7, when the vehicle is interrupted during follow-up running, the vehicle decelerates quickly with the fast pole setting, and the minimum inter-vehicle distance is about 25 m, so that there is little approach to the interrupting vehicle. On the other hand, in the case of the slow pole setting as shown in FIG.
m, and converges to the target inter-vehicle distance.

As described above, when the vehicle approaches from a long distance, and when the vehicle is interrupted while following the vehicle, conflicting response characteristics are required, and it is difficult to satisfy both the responsiveness with the uniquely determined response characteristics. Therefore, in this embodiment, attention is paid to the inter-vehicle distance under control, and the poles are set so that the response characteristics of the entire system have a slow convergence characteristic when the inter-vehicle distance is long and a fast convergence characteristic when the inter-vehicle distance is short. , And determine the gains fd and fv. Then, the gains fd and fv are changed according to the inter-vehicle distance.

A method of changing the gain based on the following distance will be described. As described above, since the response characteristics of this control system can be approximated by a secondary system, for example, ωn is set with respect to the inter-vehicle distance as shown in FIG. In this example, the distance between vehicles is 4
When the distance is shorter than 0 m, ωn is set to 0.4 to provide a fast response, and when the inter-vehicle distance is 80 m or longer, ωn is set to 0.2 to provide a slow response. Also, the distance between vehicles is 40m to 80m
During m, interpolation is performed to make the gain switching smooth. When each gain is calculated based on this ωn, the result is as shown in FIG. As shown in FIG. 9, when the inter-vehicle distance is long, the first gain fd for multiplying the inter-vehicle distance deviation ΔL is reduced, and the second gain fv for multiplying the relative speed ΔV is increased. Conversely, if the inter-vehicle distance is short, the inter-vehicle distance deviation Δ
The first gain fd multiplied by L is increased, and the relative speed ΔV
The second gain fv multiplied by is reduced.

FIG. 10 shows a simulation result of this embodiment when the vehicle approaches a preceding vehicle at a distance of 120 m at a relative speed of 20 km / s. FIG. 11 shows a relative speed of 15 km / h while following at a distance of 100 km / h and an inter-vehicle distance of 40 m. The simulation result of this embodiment in the case where the vehicle h is interrupted at the position of the inter-vehicle distance of 30 m is shown. In these figures, (a) shows own vehicle speed V and target vehicle speed V *, (b) shows inter-vehicle distance L and target inter-vehicle distance L *, and (c) shows relative speed ΔV and estimated relative speed ΔVs. (D) shows the acceleration / deceleration of the vehicle. As shown in FIG. 10, when approaching the preceding vehicle from a distance, the response characteristics are set to be slow. Therefore, after capturing the preceding vehicle, the vehicle starts decelerating at a distance of about 70 m between the vehicles, and slowly moves to the target. It converges to the following distance. Naturally, the deceleration of the vehicle is small and the impact on the occupants is small. In addition, as shown in FIG. 11, since the inter-vehicle distance during following is 40 m, fast response characteristics are set. Accordingly, deceleration is started immediately after the interruption, and the vehicle immediately converges to the target inter-vehicle distance without excessively approaching the preceding vehicle.

As described above, when the inter-vehicle distance is short, such as when interrupting the vehicle following the vehicle, the vehicle responds quickly when the vehicle approaches a distant preceding vehicle. can get.

In the above-described embodiment, an example is shown in which the automatic braking control by the braking device 6 is performed, and the actual vehicle speed follows any vehicle speed command value, that is, the deceleration of the vehicle can be ideally realized. did. However, when there is no automatic brake control, the required deceleration may not be achieved only by the engine brake, and the vehicle may approach the preceding vehicle too much. That is, for vehicles without automatic brake control, the gains fv and fd cannot be fixed as in the related art, and the gains fv and fd are switched according to the following distance as in the above-described embodiment. As a result, optimal response characteristics are always obtained.

In the above-described embodiment, an example has been described in which gain scheduling is performed.
The gain may be switched in stages or several stages.

In the configuration of the above embodiment, the following distance sensor 1 and the ranging signal processing section 11 serve as the following distance detecting means, the relative speed calculating section 501 provides the relative speed calculating means, the target following distance setting section 503 and Inter-vehicle distance control unit 5
02 denotes a vehicle speed calculating unit and a gain changing unit, the vehicle speed sensor 2 and the vehicle speed signal processing unit 21 constitute a vehicle speed detecting unit, and the vehicle speed control unit 51 constitutes a vehicle speed controlling unit.

[Brief description of the drawings]

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

FIG. 2 is a block diagram illustrating a configuration of a control system according to an embodiment.

FIG. 3 is a diagram illustrating a control system according to an embodiment.

FIG. 4 shows a relative speed of 20 km / s to a preceding vehicle at a distance of 120 m.
FIG. 9 is a diagram illustrating a simulation result of a system with a slow gain setting when approaching at a distance.

FIG. 5 shows a relative speed of 20 km / s for a preceding vehicle at a distance of 120 m.
FIG. 10 is a diagram showing a simulation result of a system with a fast gain setting when approaching with a.

FIG. 6 is a diagram illustrating a simulation result of a system with a slow gain setting when a vehicle having a relative speed of 15 km / h is interrupted by a vehicle having a relative speed of 15 km / h while following at 100 km / h and a vehicle distance of 40 m.

FIG. 7 is a diagram showing a simulation result of a system with a fast gain setting when a vehicle having a relative speed of 15 km / h is interrupted by a vehicle having a relative speed of 30 km / h while following at 100 km / h and an inter-vehicle distance of 40 m.

FIG. 8 is a diagram showing a setting example of ωn with respect to the inter-vehicle distance.

FIG. 9 is a diagram showing gains fv and fd with respect to an inter-vehicle distance.

FIG. 10 shows a relative speed of 20 km /
FIG. 14 is a diagram illustrating a simulation result of one embodiment when approaching at s.

FIG. 11 is a diagram showing simulation results of an embodiment when a vehicle having a relative speed of 15 km / h is interrupted at a position of 30 m between vehicles while following at 100 km / h and 40 m between vehicles.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 inter-vehicle distance sensor head 2 vehicle speed sensor 3 throttle actuator 4 automatic transmission 5 tracking controller 6 braking device 11 ranging 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 Distance control unit 503 Target inter-vehicle distance setting unit

Claims (4)

[Claims] An inter-vehicle distance detecting means for detecting an inter-vehicle distance; a relative speed calculating means for calculating a relative speed between the preceding vehicle and the own vehicle based on the inter-vehicle distance detection value; Speed calculation for calculating a target vehicle speed for making the inter-vehicle distance detection value the target inter-vehicle distance based on a value obtained by multiplying the deviation of the vehicle by the first gain and a value obtained by multiplying the calculated relative speed by the second gain. Means, gain changing means for changing the first gain and the second gain in accordance with the inter-vehicle distance detection value, vehicle speed detection means for detecting the own vehicle speed, so that the own vehicle speed detection value becomes the target vehicle speed. A preceding vehicle following control device, comprising: vehicle speed control means for controlling the braking / driving force of the vehicle. 2. The preceding vehicle following control device according to claim 1, wherein the gain changing means decreases the first gain and increases the second gain when the detected inter-vehicle distance is long, A preceding vehicle following control device characterized in that when the inter-vehicle distance detection value is short, the first gain is increased and the second gain is decreased. 3. The preceding vehicle following control device according to claim 1, wherein the preceding vehicle following control system is constructed by approximating the vehicle speed control system with a linear transfer function, and the detected following distance is used as the target following distance. A preceding vehicle follow-up control device, wherein the first gain and the second gain are set such that convergence characteristics for converging the calculated relative speed value to 0 become arbitrary characteristics. 4. The preceding vehicle following control device according to claim 3, wherein the natural frequency of a transfer function of the preceding vehicle following control system is given as a function of an inter-vehicle distance detection value, so that the first gain and the aforementioned A preceding vehicle following control device, wherein a second gain is set.