Cruise control system for motor vehicle

• US 6,185,499 B1
• Filed: 07/31/1998
• Issued: 02/06/2001
• Est. Priority Date: 08/11/1997
• Status: Expired due to Term

• Current Assignee: Subaru Corp.
• Original Assignee: Fuji Heavy Industries Limited (Subaru Corp.)
• Inventors: Kinoshita, Masahiro, Fukamachi, Kazuhiro
• Primary Examiner(s): Chin, Gary
• Application Number:
  US09/127,509
• Time in Patent Office: 921 Days
• Field of Search: 701/93, 701/96, 701/97, 701/98, 701/300, 701/301, 180/167-169, 180/176-179, 123/350, 123/352, 342/109, 342/454, 342/455, 340/901-904
• US Class Current: 701/96
• CPC Class Codes: B60K 31/0008 including means for detecting potential obstacles in vehicle path
• CPC Class Codes: B60W 2540/12 Brake pedal position
• CPC Class Codes: B60W 30/16 Control of distance between vehicles, e.g. keeping a distance to preceding vehicle

Abstract

A preceding vehicle, an inter-vehicle distance between a self vehicle and the preceding vehicle, vehicle speeds of the self vehicle and the preceding vehicle, an operation of a cruise control, a braking operation, a brake pressure and the like are detected and inputted to a cruise control unit. Based on these input signals, the cruise control system selects a constant speed running mode when the inter-vehicle distance is larger than a specified value and selects a following-behind running mode when the inter-vehicle distance is smaller than the specified value. When the constant speed mode is selected, the vehicle travels at a constant preset vehicle speed by operating a throttle actuator and a brake actuator. Further, when the following-behind running mode is selected, the vehicle travels keeping the inter-vehicle distance at a specified distance by the operation of the throttle actuator and the brake actuator. If the following-behind running mode lasts longer than a specified time, the preset vehicle speed is updated into a vehicle speed higher than an average vehicle speed within the specified time. Further, when a braking operation is detected during the following-behind running mode, if the brake pressure is lower than a specified value and the vehicle speed is higher than a predetermined lower limit vehicle speed, the cruise control is restored when the braking operation finishes.

Claims

1. A cruise control system of a vehicle having a first vehicle speed detecting means for detecting a first vehicle speed of said vehicle, an inter-vehicle distance detecting means for detecting an inter-vehicle distance between said vehicle and a preceding vehicle traveling ahead of said vehicle, a second vehicle speed detecting means for detecting a second vehicle speed of said preceding vehicle and an acceleration/deceleration means for accelerating or decelerating said vehicle, comprising:

a safe inter-vehicle distance calculating means for calculating a safe inter-vehicle distance based on said first vehicle speed and said second vehicle speed;

a constant speed running mode selecting means for selecting a constant speed running mode wherein said first vehicle speed of said vehicle is held at a set vehicle speed by said acceleration/deceleration means, when said inter-vehicle distance is larger than said safe inter-vehicle distance;

a following-behind running mode selecting means for selecting a following-behind running mode wherein said inter-vehicle distance is held at a predetermined value by said acceleration/deceleration means, when said inter-vehicle distance is smaller than said safe inter-vehicle distance; and

a vehicle speed updating means, when said following-behind running mode lasts longer than a specified time, for updating said set vehicle speed into a vehicle speed around an average vehicle speed within said specified time.

2. The cruise control system according to claim 1, wherein

when said following-behind running mode lasts for said specified time, said set vehicle speed is updated by a vehicle speed higher than said average vehicle speed.

3. The cruise control system according to claim 1, wherein

said inter-vehicle distance is detected by processing image signals taken by cameras.

4. The cruise control system according to claim 1, wherein

said predetermined value is equal to said safe inter-vehicle distance.

5. A cruise control system of a vehicle having a first vehicle speed detecting means for detecting a first vehicle speed of said vehicle, an inter-vehicle distance detecting means for detecting an inter-vehicle distance between said vehicle and a preceding vehicle traveling ahead of said vehicle, a second vehicle speed detecting means for detecting a second vehicle speed of said preceding vehicle, a braking operation detecting means when a braking operation is performed for detecting said braking operation, a brake pressure detecting means for detecting a brake pressure and an acceleration/deceleration means for accelerating or decelerating said vehicle, comprising:

a safe inter-vehicle distance calculating means for calculating a safe inter-vehicle distance based on said first vehicle speed and said second vehicle speed;

a constant speed running mode selecting means for selecting a constant speed running mode wherein said vehicle speed of said vehicle is held at a set vehicle speed by said acceleration/deceleration means, when said inter-vehicle distance is larger than said safe inter-vehicle distance;

a following-behind running mode selecting means for selecting a following-behind running mode wherein said inter-vehicle distance is held at a predetermined value by said acceleration/deceleration means, when said inter-vehicle distance is smaller than said safe inter-vehicle distance; and

a cruise control restoring means, when said braking operation is finished, for restoring an operation of said cruise control system stopped by said braking operation during running at said following-behind running mode, when said brake pressure is lower than a specified value and when said first vehicle speed is higher than a lower limit vehicle speed.

6. The cruise control system according to claim 5, wherein

said lower limit vehicle speed is established to be lower than said first vehicle speed when said braking operation starts.

7. The cruise control system according to claim 5, wherein

said inter-vehicle distance is detected by processing image signals taken by cameras.

8. The cruise control system according to claim 5, wherein

said predetermined value is equal to said safe inter-vehicle distance.

9. A cruise control system of a vehicle having first vehicle speed detecting means for detecting a first vehicle speed of said vehicle, inter-vehicle distance detecting means for detecting an inter-vehicle distance between said vehicle and a preceding vehicle traveling ahead of said vehicle, second vehicle speed detecting means for detecting a second vehicle speed of said preceding vehicle and acceleration/deceleration means for accelerating or decelerating said vehicle, comprising:

safe inter-vehicle distance calculating means for calculating a safe inter-vehicle distance based on said first vehicle speed and said second vehicle speed;

running mode judging means for judging a running mode of said vehicle;

constant speed running mode selecting means for selecting a constant speed running mode wherein said first vehicle speed of said vehicle is held at a set vehicle speed by said acceleration/deceleration means based on a result of said running mode judging means when said inter-vehicle distance is larger than said safe inter-vehicle distance;

following-behind running mode selecting means for selecting a following-behind running mode wherein said inter-vehicle distance is held at a predetermined value by said acceleration/deceleration means based on a result of said running mode judging means when said inter-vehicle distance is smaller than said safe inter-vehicle distance; and

vehicle speed updating means, when said following behind running mode lasts longer than a specified time, for updating said set vehicle speed into a vehicle speed around an average vehicle speed within said specified time.

10. A cruise control system of a vehicle having first vehicle speed detecting means for detecting a first vehicle speed of said vehicle, inter-vehicle distance detecting means for detecting an inter-vehicle distance between said vehicle and a preceding vehicle traveling ahead of said vehicle, second vehicle speed detecting means for detecting a second vehicle speed of said preceding vehicle, braking operation detecting means when a braking operation is performed for detecting said braking operation, brake pressure detecting means for detecting a brake pressure and acceleration/deceleration means for accelerating or decelerating said vehicle, comprising:

safe inter-vehicle distance calculating means for calculating a safe inter-vehicle distance based on said first vehicle speed and said second vehicle speed;

running mode judging means for judging a running mode of said vehicle;

constant speed running mode selecting means for selecting a constant speed running mode wherein said vehicle speed of said vehicle is held at a set vehicle speed by said acceleration/deceleration means based on a result of said running mode judging means, when said inter-vehicle distance is larger than said safe inter-vehicle distance;

following-behind running mode selecting means for selecting a following-behind running mode wherein said inter-vehicle distance is held at a predetermined value by to said acceleration/deceleration means based on a result of said running mode judging means when said inter-vehicle distance is smaller than said safe inter-vehicle distance; and

cruise control restoring means, when said braking operation is finished, for restoring an operation of said cruise control system stopped by said braking operation during running at said following-behind running mode, when said brake pressure is lower than a specified value and when said first vehicle speed is higher than a lower limit vehicle speed.

11. A cruise control system (30) of a vehicle (1) having first vehicle speed detecting means (34) mounted on said vehicle (1) for detecting a first vehicle speed (V1) thereof and for generating a first vehicle speed signal, image recognition means (22) with a pair of CCD cameras (21,21) mounted on said vehicle (1) for calculating an inter-vehicle distance (L) between said vehicle (1) and a preceding vehicle traveling ahead of said vehicle (1) by taking a stereoscopic image of said second vehicle and for generating a second vehicle speed signal and acceleration/deceleration means (25,3) for accelerating or decelerating said vehicle (1), comprising:

safe inter-vehicle distance calculating means (41) responsive to said first and second vehicle speed signals for calculating a safe inter-vehicle distance (Ls) and for producing a safe inter-vehicle distance signal;

constant speed running mode selecting means (42) responsive to said safe inter-vehicle distance signal and said second vehicle speed signal for selecting a constant speed running mode wherein said first vehicle speed (V) of said vehicle (1) is held at a set vehicle speed (VO) by said acceleration/deceleration means when said inter-vehicle distance (L) is larger than said safe inter-vehicle distance (Ls) and for generating a constant speed signal;

following-behind running mode selecting means (42′

) responsive to said constant speed signal and said first vehicle signal for selecting a following-behind running mode when said inter-vehicle distance (L) is smaller than said safe inter-vehicle distance (Ls);

vehicle speed updating means (45) responsive to said constant speed signal and said first vehicle speed signal for updating said set vehicle speed (VO) to a higher value when said following-behind running mode lasts for a specified time and for outputting an updating signal so as to run faster than ever within a predetermined safety speed; and

vehicle running control means (43) responsive to said first and second vehicle speed signals, said constant speed signal, said safe inter-vehicle distance signal, and said updating signal for controlling said acceleration/deceleration means (25,3) in an optimum running mode for each driving condition so as to avoid an unnecessary ON and OFF operation of said cruise control system (30) and frequent accelerations and decelerations of said vehicle (1) due to intentional changes by said driver.

12. The cruise control system (30) according to claim 11, wherein:

said set vehicle speed is renewed to a higher value than an averaged vehicle speed within a predetermined time when said following-behind running mode lasts for a predetermined elapsed time.

13. A cruise control system (30) of a vehicle (1) having, first vehicle speed detecting means (34) mounted on said vehicle (1) for detecting a first vehicle speed (V1) thereof and for generating a first vehicle speed signal, image recognition means (22) with a pair of CCD cameras (21,21) mounted on said vehicle (1) for calculating an inter-vehicle distance (L) between said vehicle (1) and a preceding vehicle traveling ahead of said vehicle by taking a stereoscopic image of a second vehicle preceding said vehicle (1) and for generating a second vehicle speed signal, a main switch (31) for starting an engine (2) of said vehicle (1) and for generating a main switch signal when said engine (2) is started to run, a cruise control switch (100) for setting a cruising speed of said vehicle (1) and for outputting a cruising speed signal, a vehicle speed setting switch (32) for setting a vehicle speed and for outputting a vehicle speed setting signal, a brake switch (33) for outputting a brake signal when a driver steps on a brake pedal (13), a brake pressure switch (35) provided in a brake system (12) for detecting a brake pressure (Pb) therein and for producing a brake pressure signal, and vehicle driving control means (25,26,3) for controlling said vehicle (1) in an optimum condition for each driving condition, comprising:

safe inter-vehicle distance calculating means (41) responsive to said first and second vehicle speed signals for calculating a safe inter-vehicle distance (Ls) and for producing a safe inter-vehicle distance signal;

running mode judging means (42) responsive to said safe inter-vehicle distance signal, said second vehicle speed signal, said main switch signal, said cruising speed signal, said vehicle speed setting signal and said brake signal for judging conditions whether there is an existence of said second vehicle or whether said inter-vehicle distance is more than a predetermined safe distance and for producing a judgement signal when either one of said conditions is satisfied;

following-behind running mode selecting means (42′

) responsive to said judgement signal, said brake switch signal, said first vehicle speed signal and said brake pressure signal for selecting a following-behind running mode when said inter-vehicle distance (L) is smaller than said safe inter-vehicle distance (Ls) and for generating a mode signal;

automatic cruise control restoring means (46) responsive to said mode signal, said brake signal, said first vehicle speed signal and said brake pressure signal for restoring a cruise control mode switched off by a brake operation in case of not only wherein said brake pressure (Pb) is lower than a predetermined pressure value but also wherein said vehicle speed (V1) is lower than a predetermined lower speed when said brake pedal (13) is released; and

vehicle running control means (43) responsive to said first and second vehicle speed signals, said constant speed signal, said safe inter-vehicle distance signal, and said vehicle speed setting signal, for controlling said vehicle driving control means (25,26,3) in an optimum running mode for each driving condition so as to avoid an unnecessary ON and OFF operation of said cruise control system (30) and frequent accelerations and decelerations of said vehicle (1) due to intentional changes by said driver.

14. A cruise control method of a vehicle (1) having first vehicle speed detecting means (34) mounted on said vehicle (1) for detecting a first vehicle speed (V1) thereof, image recognition means (22) with a pair of CCD cameras (21,12) mounted on said vehicle (1) for calculating an inter-vehicle distance (L) between said vehicle (1) and a preceding vehicle traveling ahead of said vehicle (1) by taking a stereoscopic image of said second vehicle, and acceleration/deceleration means (25,3) for accelerating or decelerating said vehicle (1), comprising the steps of:

calculating a safe inter-vehicle distance (Ls) from said inter-vehicle distance (L);

selecting a constant speed running mode where said first vehicle speed (V1) of said vehicle (1) is held at a set vehicle speed (VO) by said acceleration/deceleration means when said inter-vehicle distance is larger than said safe inter-vehicle distance (Ls);

selecting a following-behind running mode when said inter-vehicle distance (L) is smaller than said safe inter-vehicle distance (Ls);

updating said set vehicle speed (VO) to a higher value when said following-behind running mode lasts for a specified time so as to run faster than ever within a predetermined safety speed; and

controlling said acceleration/deceleration means (25,3) in an optimum running mode for each driving condition so as to avoid an unnecessary ON and OFF operation of said cruise control system (30) and frequent accelerations and decelerations of said vehicle (1) due to intentional changes by said driver.

15. A cruise control method of a vehicle (1) having first vehicle speed detecting means (34) mounted on said vehicle (1) for detecting a first vehicle speed (V1) thereof, image recognition means (22) with a pair of CCD cameras (21,21) mounted on said vehicle (1) for calculating an inter-vehicle distance (L) between said vehicle (1) and a preceding vehicle traveling ahead of said vehicle by taking a stereoscopic image of a second vehicle preceding said vehicle (1), a main switch (31) for starting an engine (2) of said vehicle (1), a cruise control switch (100) for setting a cruising speed of said vehicle (1), a vehicle speed setting switch (32) for setting a vehicle speed, a brake switch (33) for outputting a brake signal when a driver steps on a brake pedal (13) of the vehicle, a brake pressure switch (35) provided in a brake system (12) for detecting a brake pressure (Pb) therein and for producing a brake pressure signal, and vehicle driving control means (25,26,3) for controlling said vehicle (1) in an optimum condition for each driving condition, comprising the steps of:

calculating a safe inter-vehicle distance (Ls) from said inter-vehicle distance (L);

judging whether there is an existence of said second vehicle or whether said inter-vehicle distance is more than a predetermined safe distance;

selecting a following-behind running mode when said inter-vehicle distance (L) is smaller than said safe inter-vehicle distance (Ls);

restoring a cruise control mode switched off by a brake operation in case of not only wherein said brake pressure (Pb) is lower than a predetermined pressure value but also wherein said vehicle speed (V1) is lower than a predetermined lower speed when said brake pedal (13) is released; and

controlling said vehicle driving control means (25, 26,3) in an optimum running mode for each driving condition so as to avoid an unnecessary ON and OFF operation of said cruise control system (30) and frequent acceleration and deceleration of said vehicle (1) due to intentional changes by said driver.