Adaptive vehicle speed control system

• US 6,339,740 B1
• Filed: 07/31/2000
• Issued: 01/15/2002
• Est. Priority Date: 07/30/1999
• Status: Expired due to Term

• Current Assignee: Nissan Motor Co., Ltd.
• Original Assignee: Nissan Motor Co., Ltd.
• Inventors: Seto, Youji, Kobayashi, Yosuke, Inoue, Hideaki
• Primary Examiner(s): Cuchlinsk, Jr., William A.
• Assistant Examiner(s): Marc-Coleman, Marthe Y.
• Application Number:
  US09/629,798
• Time in Patent Office: 533 Days
• Field of Search: 701/93, 701/95, 701/96, 701/97, 701/98, 701/300, 701/301, 180/170, 180/179, 340/901, 340/902, 340/903, 340/904, 342/70, 342/71, 342/455
• US Class Current: 701/96
• CPC Class Codes: B60K 31/0008 including means for detecting potential obstacles in vehicle path
• CPC Class Codes: B60K 31/047 the memory being digital
• CPC Class Codes: B60W 2050/0022 Gains, weighting coefficients or weighting functions

Abstract

An adaptive vehicle speed control system includes a vehicle speed sensor detecting a vehicle speed of a host vehicle which is subjected to adaptive vehicle speed control including preceding vehicle following control and vehicle speed control, and an inter-vehicle distance sensor detecting an inter-vehicle distance between the host vehicle and a preceding vehicle. A man-machine interface is provided for setting a set vehicle speed. Also provided is an adaptive vehicle speed controller which includes a desired inter-vehicle distance arithmetic-processing section calculating a desired inter-vehicle distance based on at least the host vehicle speed, a following control section determining a desired speed of the host vehicle based on the host vehicle speed and the inter-vehicle distance so that the inter-vehicle distance is brought closer to the desired inter-vehicle distance in presence of detection of the preceding vehicle, and a vehicle-speed adjustment device which adjusts the host vehicle speed to the desired speed. The adaptive vehicle speed controller includes a vehicle speed setting section which sets the desired speed to a speed value higher than a low-speed threshold value when the adaptive vehicle speed control function is engaged under a specified condition where the host vehicle speed is below the low-speed threshold value.

Claims

1. An adaptive vehicle speed control system comprising:

a vehicle speed detection device which detects a vehicle speed of a host vehicle which is subjected to adaptive vehicle speed control including preceding vehicle following control and vehicle speed control;

an inter-vehicle distance detection device which detects an inter-vehicle distance between the host vehicle and a preceding vehicle ahead of the host vehicle;

a set-vehicle-speed setting device having a man-machine interface for setting a set vehicle speed;

a vehicle speed controller comprising;

a desired inter-vehicle distance arithmetic-processing section calculating a desired inter-vehicle distance based on at least the host vehicle speed; and

a following control section determining a desired speed of the host vehicle based on the host vehicle speed and the inter-vehicle distance so that the inter-vehicle distance is brought closer to the desired inter-vehicle distance in presence of detection of the preceding vehicle; and

a vehicle-speed adjustment device which adjusts the host vehicle speed to the desired speed determined by said vehicle speed controller; and

an adaptive-vehicle-speed-control initiation command device which outputs a command signal indicative of initiation of the adaptive vehicle speed control including the following control performed through the following control section and the vehicle speed control performed through the vehicle speed control section;

wherein said vehicle speed controller includes a vehicle speed setting section which sets the desired speed determined by said vehicle speed controller to a speed value higher than a low-speed threshold value, in presence of output of the command signal under a specified condition where the host vehicle speed is below the low-speed threshold value.

2. The adaptive vehicle speed control system as claimed in claim 1, wherein said vehicle speed controller further comprises an acceleration setting section which sets a maximum value of acceleration allowed by both the following control section and the vehicle speed control section at a first set value in presence of output of the command signal under the specified condition where the host vehicle speed is below the low-speed threshold value, and sets the maximum value of acceleration at a second set value higher than the first set value when the set vehicle speed set by the man-machine interface exceeds the low-speed threshold value.

3. The adaptive vehicle speed control system as claimed in claim 2, wherein said acceleration setting section sets the maximum value of acceleration at a third set value higher than the second set value in presence of detection of the preceding vehicle.

4. The adaptive vehicle speed control system as claimed in claim 2, wherein said vehicle speed controller further comprises an acceleration-and-deceleration setting section programmed to perform the following,

(a) calculating a speed deviation as a difference between the set vehicle speed and the host vehicle speed;

(b) calculating a first acceleration-and-deceleration value G*_V used for the vehicle speed control from a first expression G*_V=(K_P+K_I/s+K_D·

s)Ve, where s denotes a Laplace variable, K_P, K_I, and K_D respectively denote a proportional gain, an integral gain, and a derivative gain, and Ve is the speed deviation;

(c) calculating an inter-vehicle distance deviation as a difference between the inter-vehicle distance detected by said inter-vehicle distance detection device and the desired inter-vehicle distance;

(d) calculating a relative speed of the preceding vehicle with respect to the host vehicle speed, by differentiating the inter-vehicle distance detected;

(e) calculating a second acceleration-and-deceleration value G*_L used for the following control from a second expression G*_L=F₁Δ

L+F₂Δ

V, where F₁ and F₂ are coefficients, Δ

L denotes the inter-vehicle distance deviation, and Δ

V denotes the relative speed;

(f) setting the first acceleration-and-deceleration value G*_V as a desired acceleration-and-deceleration value in absence of detection of the preceding vehicle;

(g) setting a lower one of the first and second acceleration-and-deceleration values G*_V and G*_L as the desired acceleration-and-deceleration value in presence of detection of the preceding vehicle;

(h) comparing the desired acceleration-and-deceleration value with the maximum value of acceleration; and

(i) limiting the desired acceleration-and-deceleration value to the maximum value of acceleration only when the desired acceleration-and-deceleration value exceeds the maximum value of acceleration.

5. The adaptive vehicle speed control system as claimed in claim 4, wherein vehicle acceleration and deceleration of the host vehicle are adjusted by engine torque control and brake control depending on the desired acceleration-and-deceleration value during the adaptive vehicle speed control.

6. The adaptive vehicle speed control system as claimed in claim 1, which further comprises an automatic transmission which permits a creeping travel of the host vehicle without depression of an accelerator in a low vehicle speed range, and the low-speed threshold value is set at a speed value higher than a creep speed given during the creeping travel.

7. The adaptive vehicle speed control system as claimed in claim 1, wherein the low-speed threshold value is set at a speed value higher than a speed at which the low-speed threshold value is maintained with no need of a braking force.

8. The adaptive vehicle speed control system as claimed in claim 1, wherein the low-speed threshold value is set at a speed value higher than a speed at which the host vehicle runs without any throttle opening and without any braking force.

9. An adaptive vehicle speed control system comprising:

a vehicle speed detection means for detecting a vehicle speed of a host vehicle which is subjected to adaptive vehicle speed control including preceding vehicle following control and vehicle speed control;

an inter-vehicle distance detection means for detecting an inter-vehicle distance between the host vehicle and a preceding vehicle ahead of the host vehicle;

a set-vehicle-speed setting means having a man-machine interface for setting a set vehicle speed;

a vehicle speed controller comprising;

a desired inter-vehicle distance arithmetic-processing means for calculating a desired inter-vehicle distance based on at least the host vehicle speed; and

a following control means for determining a desired speed of the host vehicle based on the host vehicle speed and the inter-vehicle distance so that the inter-vehicle distance is brought closer to the desired inter-vehicle distance in presence of detection of the preceding vehicle; and

a vehicle-speed adjustment means for adjusting the host vehicle speed to the desired speed determined by said vehicle speed controller; and

an adaptive-vehicle-speed-control initiation command means for outputting a command signal indicative of initiation of the adaptive vehicle speed control including the following control performed through the following control means and the vehicle speed control performed through the vehicle speed control means;

wherein said vehicle speed controller includes a vehicle speed setting means for setting the desired speed determined by said vehicle speed controller to a speed value higher than a low-speed threshold value, in presence of output of the command signal under a specified condition where the host vehicle speed is below the low-speed threshold value.

10. An adaptive vehicle speed control method, which comprises:

detecting a vehicle speed of a host vehicle which is subjected to adaptive vehicle speed control including preceding vehicle following control and vehicle speed control;

detecting an inter-vehicle distance between the host vehicle and a preceding vehicle ahead of the host vehicle;

setting a set vehicle speed through a man-machine interface;

calculating a desired inter-vehicle distance based on at least the host vehicle speed;

determining a desired speed of the host vehicle based on the host vehicle speed and the inter-vehicle distance so that the inter-vehicle distance is brought closer to the desired inter-vehicle distance in presence of detection of the preceding vehicle;

adjusting the host vehicle speed to the desired speed;

outputting a command signal indicative of initiation of the adaptive vehicle speed control including the following control and the vehicle speed control; and

setting the desired speed to a speed value higher than a low-speed threshold value, in presence of output of the command signal under a specified condition where the host vehicle speed is below the low-speed threshold value.