Vehicle dynamic control system

• US 6,188,316 B1
• Filed: 03/11/1999
• Issued: 02/13/2001
• Est. Priority Date: 03/12/1998
• Status: Expired due to Term

• Current Assignee: Subaru Corp.
• Original Assignee: Fuji Jukogyo KK (Subaru Corp.)
• Inventors: Matsuno, Koji, Matsuura, Munenori
• Primary Examiner(s): Lieu, Julie
• Application Number:
  US09/266,627
• Time in Patent Office: 705 Days
• Field of Search: 340/441, 340/425.5, 701/1, 701/23, 701/65, 701/70, 701/121, 701/200, 701/201, 701/93
• US Class Current: 340/441
• CPC Class Codes: B60Q 9/00 Arrangement or adaptation of signal devices not provided for in one of main groups B60Q1/00 - B60Q7/00 , e.g. haptic signalling
• CPC Class Codes: B60T 2260/04 Automatic transmission
• CPC Class Codes: B60T 8/1755 Brake regulation specially adapted to control the stability of the vehicle, e.g. taking into account yaw rate or transverse acceleration in a curve road vehicle drive control systems for control of driving stability otherwise than by controlling a particular sub-unit B60W30/02
• CPC Class Codes: B60W 10/04 including control of propulsion units
• CPC Class Codes: B60W 10/06 including control of combustion engines
• CPC Class Codes: B60W 10/10 including control of change-speed gearings
• CPC Class Codes: B60W 10/184 with wheel brakes
• CPC Class Codes: B60W 2050/0051 combined with averaging
• CPC Class Codes: B60W 2050/0071 Controller overrides driver automatically
• CPC Class Codes: B60W 2510/182 Brake pressure, e.g. of fluid or between pad and disc
• CPC Class Codes: B60W 2520/10 Longitudinal speed
• CPC Class Codes: B60W 2520/105 Longitudinal acceleration
• CPC Class Codes: B60W 2520/125 Lateral acceleration
• CPC Class Codes: B60W 2556/50 of positioning data, e.g. GPS [Global Positioning System] data
• CPC Class Codes: B60W 30/18172 Preventing, or responsive to skidding of wheels
• CPC Class Codes: B60W 40/072 Curvature of the road
• CPC Class Codes: B60W 40/076 Slope angle of the road
• CPC Class Codes: B60W 50/14 Means for informing the driver, warning the driver or prompting a driver intervention

Abstract

Recognizing curve geometry, judgement accuracy of an over speed condition is improved with minimal increase of calculation load, even when the road to an objective curve is not a straight line. The standard deceleration calculator calculates a standard deceleration from the road surface friction coefficient and road slope. The permissible access speed calculator calculates a permissible access speed from the permissible lateral acceleration based on road geometry and the road surface friction coefficient. The equivalent linear distance calculator calculates an equivalent linear distance, converting a winding part of a road to the objective curve into an equivalent straight line. The passing judgement device compares a required deceleration, which is determined based on the present vehicle speed, the permissible access speed and the equivalent linear distance, with a warning deceleration level and a forced deceleration level, which are calculated from the standard deceleration. According to the comparison result, the warning deceleration controller carries out a warning control through the display and a loudspeaker and forced deceleration control by the engine control unit, the transmission control unit and the brake control unit.

Claims

1. A vehicle dynamic control system comprising:

a running condition detecting means for detecting running conditions of a vehicle;

a road data detecting means for detecting road data relating to a road in front of the vehicle;

a worth judging distance calculating means for calculating a worth judging distance from a point of operation to a curve on the road in front of the vehicle based on said road data, said worth judging distance being corrected and reduced according to a curvature of a winding part of the road between said point of operation and the curve, wherein said worth judging distance calculating means includes equivalent linear distance calculating means responsive to a coefficient signal relating to road friction characteristics, said road data, and a warning deceleration threshold level, said equivalent linear distance calculating means for deriving a linear distance equivalent to a shortened distance of the curve and for generating a linear distance signal which is provided to the passing judgement means;

a passing judgement means for judging a possibility of the vehicle passing through the curve based on said worth judging distance calculated by said worth judging distance calculating means; and

a warning and deceleration control means for activating at least one of a warning means and a decelerating means based on a judgement of said passing judgement means.

2. The vehicle dynamic control system according to claim 1, wherein said worth judging distance calculating means determines said worth judging distance taking into consideration a permissible deceleration applicable at said winding part of the road in addition to the curvature of said winding part of the road, said worth judging distance calculating means calculating said permissible deceleration by a friction circle relation between longitudinal and lateral accelerations of the vehicle.

3. The vehicle dynamic control system according to claim 1, wherein said passing judgement means judges said possibility of the vehicle passing through the curve according to estimated running conditions based on present running conditions at said point of operation and permissible running conditions based on running conditions for passing through the curve.

4. The vehicle dynamic control system according to claim 3, wherein said estimated running conditions include a standard deceleration applicable at said point of operation;

said permissible running conditions include a permissible access speed for passing through said curve;

said passing judgement means calculates a required deceleration to be applied until reaching the curve based on said permissible access speed, a vehicle speed at said point of operation and said worth judging distance; and

said passing judgement means judges said possibility of the vehicle passing through the curve by comparing said standard deceleration and said required deceleration in a predetermined manner.

5. A dynamic control system of a vehicle, comprising:

road surface friction coefficient estimating means responsive to a vehicle speed signal, a steering signal, and a yaw rate signal for calculating a road surface friction coefficient by comparing a cornering power of each vehicle wheel and for generating a coefficient signal;

road inclination calculating means responsive to said vehicle speed signal and a longitudinal acceleration signal for calculating a degree of road slope using a predetermined equation and for generating a slope signal;

warning deceleration value calculating means responsive to said slope signal and said coefficient signal for determining a permissible deceleration value by deriving a reference deceleration value from said road slope and said road surface friction coefficient and for producing a warning deceleration signal;

forced deceleration value calculating means for calculating a forced deceleration value from the reference deceleration value, the forced deceleration value relating to an amount of deceleration required for safely passing the curve and for generating a forced deceleration value signal;

acceptable curve-entering speed calculating means responsive to said coefficient signal and a road information signal providing information relating to characteristics of the road, said acceptable curve-entering speed calculating means for calculating a permissible speed in order to enter a curve by referring to a permissible acceleration value for said road information and for outputting a permissible entering speed signal;

equivalent linear distance calculating means responsive to said coefficient signal, said road information signal, and said warning deceleration signal for deriving a linear distance equivalent to a shortened distance of the curve and for generating a linear distance signal;

required deceleration value calculating means responsive to said warning deceleration signal, permissible entering speed signal, said vehicle speed signal, and said linear distance signal for calculating a required deceleration value from a predetermined equation relating to said road information and said vehicle speed and for outputting a required deceleration signal;

passing possibility judgement means responsive to said required deceleration signal, said warning deceleration signal, and said forced deceleration value signal for judging a possibility of passing through the curve in accordance with said required deceleration value and for generating a possibility signal; and

warning control means connected to an engine of the vehicle, transmission control means, and a brake control system, responsive to said possibility signal, said required deceleration signal, said warning deceleration signal, and said forced deceleration value signal for warning a driver of the vehicle of an over speed condition or reducing vehicle speed to a speed that enables the vehicle to safely pass the curve even if a portion of the road before entering the curve is curved.

6. The dynamic control system according to claim 5, wherein:

said equivalent linear distance calculating means determines said linear distance in accordance with a curvature degree of the curve and a deceleration amount predicted before the vehicle enters the curve based upon a friction circle defined by longitudinal and lateral accelerations of the vehicle.

7. The vehicle dynamic control system according to claim 5, wherein:

said passing possibility judgement means judges, before the vehicle enters the curve, whether the vehicle can pass through the curve in accordance with a permissible condition, based on a presently running condition, and an estimated running condition, based upon a permissible running condition.

8. The vehicle dynamic control system according to claim 7, wherein:

said estimated running condition is a reference deceleration value estimated when starting a turn is judged;

said permissible running condition is a permissible curve entering speed; and

said passing possibility judgement means judges whether the vehicle can pass through the curve by comparing a predetermined deceleration amount with said reference deceleration and a first deceleration amount required for entering the curve calculated from said permissible curve entering speed, said vehicle speed, and said linear distance.

9. A dynamic control method of a vehicle, comprising:

estimating a road surface friction coefficient by comparing a cornering power of each vehicle wheel;

determining a degree of road slope;

determining a permissible deceleration value by deriving a reference deceleration value based upon the road slope and the road surface friction coefficient;

deriving a forced deceleration value based upon an amount of deceleration required for safely passing the curve;

computing a permissible speed for entering the curve based upon a permissible acceleration value for the road, which is determined based upon information relating to the road;

determining a linear distance equivalent for the curve;

determining a required deceleration value from a predetermined equation as a function of said information relating to the road and said vehicle speed;

judging a possibility of passing through the curve in accordance with said required deceleration value; and

warning a driver of the vehicle or adjusting the vehicle speed to enable the vehicle to safely pass the curve even if a road before entering the curve is curved.