Intelligent cruise control system for moving body

• US 6,044,321 A
• Filed: 06/09/1997
• Issued: 03/28/2000
• Est. Priority Date: 06/07/1996
• Status: Expired due to Fees

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Matsuura, Kazuo, Nakamura, Mitsuru, Kuragaki, Satoru, Hanawa, Kazuhiko
• Primary Examiner(s): Zanelli, Michael J.
• Application Number:
  US08/871,887
• Time in Patent Office: 1,023 Days
• Field of Search: 701/93, 701/96, 701/301, 180/170, 180/178, 180/179, 342/70, 342/71, 123/349, 303/193
• 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 2520/10 Longitudinal speed
• 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

Abstract

An intelligent cruise control system is capable of maintaining a car-to-car distance allowing a collision to be avoided and carrying out follow-up running control without providing a sense of incompatibility to the driver. A radar circuit employed in a radar unit calculates a relative speed Vr of a car running ahead of a vehicle with an intelligent cruise control system installed therein with respect to the vehicle and a distance dr from the vehicle to the preceding car from a wave reflected by the preceding car. An ICC unit adjusts the speed of the vehicle by controlling the output of the engine of the vehicle in accordance with information such as the relative speed Vr and the distance dr received from the radar unit. In a follow-up running mode, the ICC unit controls the cruise of the vehicle in such a way that the speed of the vehicle and the distance from the vehicle to the preceding car are maintained at a target speed and a target car-to-car distance respectively. When the ICC unit forms a judgment that deceleration of the vehicle is not enough if only deceleration based on the engine brake is relied on, giving rise to fear of a rear-end collision of the vehicle with the preceding car, the ICC unit calculates a target deceleration and operates an automatic brake unit, letting the automatic brake unit generate a braking force appropriate for the target acceleration.

Claims

1. An intelligent cruise control system for a moving body for controlling the cruise of said moving body, said system comprising:

a distance detecting means for measuring a distance from said moving body to an object of attention existing in front of said moving body;

a speed detecting means for measuring the speed of said moving body;

a braking-distance estimating means for estimating a distance along which said moving body travels to decelerate to a specially set deceleration target speed; and

a deceleration means for comparing an estimated braking distance estimated by said braking-distance estimating means with a distance measured by said distance detecting means and for decelerating said moving body if a comparison result indicates that said estimated braking distance is longer.

2. An intelligent cruise control system for a moving body according to claim 1 further comprising:

a constant-speed running means for letting said moving body run at a specially determined target speed; and

a target-speed modifying means for comparing said estimated braking distance with a distance measured by said distance detecting means and for reducing said target speed if a comparison result indicates that said estimated braking distance is longer.

5. An intelligent cruise control system for a moving body according to claim 1 further comprising:

a speed monitoring means for measuring the speed of said moving body or said object of attention;

a minimum-monitored-speed determining means for selecting a speed representing a lowest speed range as a minimum monitored speed among speed ranges each with a speed-occurrence count equal to or greater than a predetermined threshold value with said speed-occurrence count obtained as a result of monitoring carried out by said speed monitoring means during a specially determined period of time; and

a deceleration-target-speed determining means for determining said deceleration target speed based on said minimum monitored speed.

6. An intelligent cruise control system for a moving body according to claim 5 wherein said deceleration-target-speed determining means uses said minimum monitored speed as said deceleration target speed as it is.

9. An intelligent cruise control system according to claim 1, wherein said specially set deceleration target speed is based on a speed of at least one of the moving body and the object of attention, said specially set deceleration target speed not equaling zero.

10. An intelligent cruise control system for a moving body according to claim 9 wherein said operation means is an accelerator pedal and a brake pedal.

11. An intelligent cruise control system for a moving body according to claim 1 further comprising:

a relative-speed control means for adjusting the speed of said moving body by modifying specially determined control gains so as to decrease the relative speed of said moving body with respect to said object of attention;

operation means to be operated by the driver to issue a command requesting car-speed adjustment; and

a gain adjusting means for increasing said control gains in accordance with a command for raising the speed of said moving body issued as a result of operating said operation means and, on the other hand, for decreasing said control gains in accordance with a command for reducing the speed of said moving body issued as a result of operating said operation means.

12. An intelligent cruise control system according to claim 10, wherein said specially determined deceleration target speed is based on a speed of at least one of the moving body and the object of attention, said specially determined deceleration target speed not equaling zero.

3. An intelligent cruise control system for a moving body for controlling the cruise of said moving body, said system comprising:

a distance detecting means for measuring a distance from said moving body to an object of attention existing in front of said moving body;

a relative-speed detecting means for measuring a relative speed of said moving body with respect to said object of attention;

a speed detecting means for measuring the speed of said moving body;

a time-to-collision estimating means for estimating a time to a collision with said object of attention from a relative speed measured by said relative-speed detecting means and a distance measured by said distance detecting means;

a braking-time estimating means for estimating a time it takes to decelerate said moving body to a specially determined deceleration target speed; and

a deceleration means for comparing an estimated braking time estimated by said braking-time estimating means with a time estimated by said time-to-collision estimating means and for decelerating said moving body if a comparison result indicates that said estimated braking time is longer.

4. An intelligent cruise control system for a moving body according to claim 3 further comprising:

a constant-speed running means for letting said moving body run at a specially determined target speed; and

a target-speed modifying means for comparing said estimated braking time with a time estimated by said time-to-collision estimating means and for reducing said target speed if a comparison result indicates that said estimated braking time is longer.

7. An intelligent cruise control system for a moving body for controlling the cruise of said moving body, said system comprising:

a speed monitoring means for measuring the speed of said moving body or an object of attention existing in front of said moving body;

a monitored-speed determining means for selecting a speed representing a highest speed range as a monitored speed among speed ranges each with a speed-occurrence count equal to or greater than a predetermined threshold value with said speed-occurrence count obtained as a result of monitoring carried out by said speed monitoring means during a specially determined period of time;

a target-speed determining means for determining a target speed based on said monitored speed; and

a constant-speed running means for letting said moving body run at said determined target speed.

8. An intelligent cruise control system for a moving body according to claim 7 wherein said target-speed determining means uses said monitored speed as said target speed as it is.

13. An intelligent cruise control system for a moving body for controlling the cruise of said moving body provided with an engine and a brake, said system comprising:

an attention-object detecting means for measuring the distance from said moving body to an object of attention existing in front of said moving body, the relative speed of said object of attention with respect to said moving body and a relative angle formed by a line connecting said moving body to said object of attention and the running direction of said moving body;

a transversal-position inferring means for calculating the transversal-direction component of said distance from said moving body to said object of attention from said relative angle measured by said attention-object detecting means;

a speed detecting means for measuring the speed of said moving body; and

a collision-avoidance control means which is used for decelerating said moving body if;

said relative speed detected by said attention-object detecting means is negative;

the absolute value of said relative speed is greater than the absolute value of said speed of said moving body measured by said speed detecting means;

said transversal-direction component of said distance calculated by said transversal-position inferring means is equal to or smaller than a predetermined value; and

said distance from said moving body to said object of attention measured by said attention-object detecting means is equal to or smaller than a specifically determined value.

14. An intelligent cruise control system for a moving body according to claim 13 wherein said collision-avoidance control means selectively uses either an engine brake or said brake in dependence upon the magnitude of said distance from said moving body to said object of attention measured by said attention-object detecting means.

15. An intelligent cruise control system for a moving body according to claim 14 further having a reporting means which is used for reporting that said object of attention is approaching said moving body if:

said relative speed detected by said attention-object detecting means is negative;

the absolute value of said relative speed is greater than the absolute value of said speed of said moving body measured by said speed detecting means;

said transversal-direction component of said distance calculated by said transversal-position inferring means is equal to or smaller than a predetermined value; and

said distance from said moving body to said object of attention measured by said attention-object detecting means is equal to or smaller than a specially determined value.