Vehicular velocity controlling apparatus and method to follow up a preceding vehicle running ahead of vehicle

• US 6,345,227 B1
• Filed: 06/12/2000
• Issued: 02/05/2002
• Est. Priority Date: 06/15/1999
• Status: Active Grant

• Current Assignee: Nissan Motor Co., Ltd.
• Original Assignee: Nissan Motor Co., Ltd.
• Inventors: Tange, Satoshi, Egawa, Kenichi, Higashimata, Akira, Asada, Tetsuya
• Primary Examiner(s): Cuchlinski, Jr., William A.
• Assistant Examiner(s): Hernandez, Olga
• Application Number:
  US09/592,568
• Time in Patent Office: 603 Days
• Field of Search: 701/96, 701/93, 701/78, 701/79, 701/70, 701/36, 701/83, 701/91, 180/168, 180/169, 180/170
• US Class Current: 701/96
• CPC Class Codes: B60K 31/0008 including means for detecting potential obstacles in vehicle path
• CPC Class Codes: B60W 2554/801 Lateral distance
• CPC Class Codes: B60W 2720/106 Longitudinal acceleration
• CPC Class Codes: B60W 30/16 Control of distance between vehicles, e.g. keeping a distance to preceding vehicle
• CPC Class Codes: G08G 1/166 for active traffic, e.g. moving vehicles, pedestrians, bikes

Abstract

In vehicular velocity controlling method and apparatus for an automotive vehicle, an inter-vehicle distance from the vehicle to a preceding vehicle which is running ahead of the vehicle is detected, a target vehicular velocity is calculated to make a detected value of the inter-vehicle distance substantially equal to a target inter-vehicle distance, a vehicular velocity of the vehicle is detected, the vehicular velocity of the vehicle is adjustably controlled to make a detected value of the vehicular velocity substantially equal to the target vehicular velocity, a target braking pressure for a vehicular brake system is calculated in accordance with a target deceleration variable calculated on the basis of the target vehicular velocity and the detected value of the vehicular velocity; and a limitation on a rate of increase in the target braking pressure is placed when the target braking pressure is in excess of a predetermined braking pressure threshold value.

Claims

1. A vehicular velocity controlling apparatus for an automotive vehicle, comprising:

an inter-vehicle distance detector to detect an inter-vehicle distance from the vehicle to a preceding vehicle which is running ahead of the vehicle;

an inter-vehicle distance calculating section that calculates a target vehicular velocity to make a detected value of the inter-vehicle distance substantially equal to a target inter-vehicle distance;

a vehicular velocity detector to detect a vehicular velocity of the vehicle; and

a vehicular velocity controlling section that adjustably controls the vehicular velocity of the vehicle to make a detected value of the vehicular velocity substantially equal to the target vehicular velocity, the vehicular velocity controlling section including a target braking pressure calculating section that calculates a target braking pressure for a vehicular brake system in accordance with a target deceleration variable calculated on the basis of the target vehicular velocity and the detected value of the vehicular velocity; and

a target braking pressure limiter to place a limitation on a rate of increase in the target braking pressure when the target braking pressure is in excess of a predetermined braking pressure threshold value.

2. A vehicular velocity controlling apparatus for an automotive vehicle as claimed in claim 1, wherein the target braking pressure limiter places the limitation on the rate of increase in the target braking pressure in such a manner that the rate of increase therein is increased in a substantially step change manner at an initial stage of the increase in the braking pressure and, thereafter, is increased relatively gradually up to the target braking pressure.

3. A vehicular velocity controlling apparatus for an automotive vehicle as claimed in claim 1, wherein the target braking pressure limiter places the limitation on the rate of increase in the target braking pressure in such a manner that the rate of increase in the braking pressure is increased gradually up to the target braking pressure at an initial stage of the increase in the target braking pressure.

4. A vehicular velocity controlling apparatus for an automotive vehicle as claimed in claim 1, wherein the target braking pressure limter places the limitation on the rate of increase in the braking pressure in such a manner that the rate of increase in the braking pressure is increased in a substantially step change manner at an initial stage of an increase in the braking pressure when a magnitude of the target braking pressure is equal to or larger than a predetermined magnitude of the braking pressure and in such a manner that the rate of increase in the target braking pressure is increased gradually up to the target braking pressure when the magnitude of the target braking pressure is smaller than the predetermined magnitude.

5. A vehicular velocity controlling apparatus for an automotive vehicle as claimed in claim 2, wherein the vehicular velocity controlling section includes a target vehicular driving force calculating section that calculates a target vehicular driving force to make the detected value of the vehicular velocity substantially equal to the target vehicular velocity and wherein the vehicular velocity controlling section controls a driving force exerted by a rotary driving force source, a gear position of a vehicular transmission, and the braking pressure exerted by the vehicular brake system on the basis of the target vehicular driving force and calculates the present target braking pressure P_B*(n) on the basis of the target driving force when the target driving force indicates a negative value exceeding the predetermined braking pressure threshold value Ps.

6. A vehicular velocity controlling apparatus for an automotive vehicle as claimed in claim 5, wherein the target braking pressure limiter includes:

a first comparator to compare the present target braking pressure P_B*(n) with a one previous target braking pressure P_B*(n−

1) to determine if P_B*(n)≧

P_B(n−

1);

a second comparator to compare the present target braking pressure P_B*(n) with the predetermined braking pressure threshold value Ps to determine if P_B*(n)>

Ps when the first comparator determines that P_B*(n)≧

P_B*(n−

1);

a braking pressure command value generator to generate a braking pressure command value P_BD as follows;

P_BD=P_BD+Δ

P_BA, wherein Δ

P_BA denotes a predetermined value to determine a gradient of the rate of increase in the target braking pressure with respect to a predetermined period of time when the second comparator determines that P_B*(n)>

Ps;

a third comparator to compare the braking pressure command value P_BD with the present target braking pressure P_B*(n) to determine if P_BD≧

P_B*(n) when the second comparator determines that P_BD>

Ps; and

a brake pressure command value output device that outputs the braking pressure command value P_BD to a vehicular brake controller as follows;

P_BD=P_B*(n) when the third comparator determines that P_BD≧

P_B*(n) or when the second comparator determines that P_B*(n)≦

Ps.

7. A vehicular velocity controlling apparatus as claimed in claim 6, wherein the braking pressure command value generator generates the braking pressure command value P_BD as follows when the first comparator determines that P_B*(n)<

P_B*(n−

1);

P_BD=P_BD−

Δ

P_BD, wherein Δ

P_BD denotes another predetermined value to determine a gradient of a rate of decrease in the target braking pressure with respect to the predetermined period of time.

8. A vehicular velocity controlling apparatus for an automotive vehicle as claimed in claim 6, wherein the target braking pressure limiter further includes:

an initial state determinator to determine whether a present vehicular running state falls in an initial state of the vehicular braking through the vehicular brake system in accordance with the target driving force when the second comparator determines that P_B* (n)>

Ps and wherein the brake pressure command value output device outputs the brake pressure command value P_BD to the brake controller as follows;

P_BD=Ps when the initial state determinator determines that the present vehicular running state falls in the initial state of braking.

9. A vehicular velocity controlling apparatus for an automotive vehicle as claimed in claim 6, wherein after the output of the pressure command value P_BD=Ps, the braking pressure command value output device outputs the brake pressure command value using the generated value at the braking pressure command generator as follows:

P_BD=P_BD+Δ

P_BA.

10. A vehicular velocity controlling apparatus as claimed in claim 8, wherein the target braking pressure limiter further includes a fourth comparator to compare a deviation between the present target braking pressure P_B*(n) and the one previous target braking pressure P_B*(n−

1) to determine if P_B*(n)−

P_B*(n−

1)≧

Ps2, wherein Ps2 denotes a predetermined magnitude of the target braking pressure and Ps2>

Ps when the second comparator determines that P_B*(n)>

Ps and wherein the braking pressure command value output device outputs the braking pressure command value to the brake controller using the generated value of the braking pressure command value generator as follows;

P_BD=Ps when the initial state determinator determines that the present vehicular running state falls in the initial state of the vehicular braking.

11. A vehicular velocity controlling apparatus for an automotive vehicle, comprising:

inter-vehicle distance detecting means for detecting an inter-vehicle distance from the vehicle to a preceding vehicle which is running ahead of the vehicle;

inter-vehicle distance calculating means for calculating a target vehicular velocity to make a detected value of the inter-vehicle distance substantially equal to a target inter-vehicle distance;

vehicular velocity detecting means for detecting a vehicular velocity of the vehicle;

vehicular velocity controlling means for adjustably controlling the vehicular velocity of the vehicle to make a detected value of the vehicular velocity substantially equal to the target vehicular velocity, the vehicular velocity controlling means including;

target braking pressure calculating means for calculating a target braking pressure for a vehicular brake system in accordance with a target deceleration variable calculated on the basis of the target vehicular velocity and the detected value of the vehicular velocity; and

target braking pressure limiting means for placing a limitation on a rate of increase in the target braking pressure when the target braking pressure is in excess of a predetermined braking pressure threshold value.

12. A vehicular velocity controlling method for an automotive vehicle, comprising:

detecting an inter-vehicle distance from the vehicle to a preceding vehicle which is running ahead of the vehicle;

calculating a target vehicular velocity to make a detected value of the inter-vehicle distance substantially equal to a target inter-vehicle distance;

detecting a vehicular velocity of the vehicle;

adjustably controlling the vehicular velocity of the vehicle to make a detected value of the vehicular velocity substantially equal to the target vehicular velocity;

calculating a target braking pressure for a vehicular brake system in accordance with a target deceleration variable calculated on the basis of the target vehicular velocity and the detected value of the vehicular velocity; and

placing a limitation on a rate of increase in the target braking pressure when the target braking pressure is in excess of a predetermined braking pressure threshold value.