Vehicular dynamic controlling apparatus and method

• US 6,615,124 B1
• Filed: 03/31/2000
• Issued: 09/02/2003
• Est. Priority Date: 04/02/1999
• Status: Active Grant

• Current Assignee: Nissan Motor Co., Ltd.
• Original Assignee: Nissan Motor Co., Ltd.
• Inventors: Adachi, Kazutaka
• Primary Examiner(s): Louis-Jacques, Jacques H.
• Assistant Examiner(s): Broadhead, Brian J
• Application Number:
  US09/540,889
• Time in Patent Office: 1,250 Days
• Field of Search: 701/36, 701/41, 701/72, 701/78, 701/43, 701/79, 701/80, 303/140, 303/146, 180/445, 180/410, 180/411, 280/5.507
• US Class Current: 701/70
• CPC Class Codes: B60T 2260/02 Active Steering, Steer-by-Wire
• 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: B62D 6/04 responsive only to forces disturbing the intended course of the vehicle, e.g. forces acting transversely to the direction of vehicle travel
• CPC Class Codes: B62D 7/159 characterised by computing methods or stabilisation processes or systems, e.g. responding to yaw rate, lateral wind, load, road condition

Abstract

Vehicular dynamic controlling apparatus and method for an automotive vehicle which can achieve a desired yaw rate output in response to a steering input by a vehicular driver even when the controlled vehicle is running in such a cornering limit range such that a vehicular lateral acceleration is relatively large without giving a steering maneuver different from that the vehicular driver desires to the vehicular driver. The vehicular dynamic controlling apparatus includes: brake force distribution controlling section and brake pressure controlling section which control a brake force for each tire wheel of the controlled vehicle so as to eliminate a deviation between an estimated value of a (steady state) yaw rate gain Y_G and a target value of the yaw rate gain Y_GT; and rear tire wheel angular displacement controlling section and rear tire steering angular displacement actuator which control a rear tire wheel steering angular displacement to make a rear tire wheel steering angular displacement command value δ_RC coincident with an actual rear tire wheel steering angular displacement δ_RR. The rear tire steering angular displacement command value δ_RC is calculated from detected values of the vehicular velocity V (or ν) and a steering angular displacement θ of a steering wheel, target vehicular dynamical variables, a tire performance information, and a previously measured controlled vehicular dynamic model.

Claims

1. A vehicular dynamic controlling apparatus comprising:

a vehicular velocity sensor to detect a vehicular velocity;

a steering angular displacement sensor to detect a steering angular displacement of a vehicular steering wheel;

a yaw rate sensor to detect a vehicular yaw rate;

a yaw rate gain estimating section that estimates a vehicular yaw rate gain from detected values of the vehicular velocity, the yaw rate, and the steering angular displacement;

a target yaw rate gain setting section that sets a target value of the yaw rate gain;

a brake force distribution controlling section that calculates a brake force command value for each of vehicular front left and right and rear left and right tire wheels to reduce a deviation between an estimated value of the yaw rate gain and the target value thereof;

a brake pressure controlling section that controls a brake pressure to be applied to each tire wheel in accordance with the brake force command value for each tire wheel;

a tire information calculating section that calculates a tire information related to a vehicular dynamic information on the basis of the brake force command value for each tire wheel individually and previously measured tire data;

a rear tire wheel steering actuator to be enabled to actuate the rear tire wheels to be steered;

a target vehicular dynamical variable calculating section that calculates target vehicular dynamical variables on the basis of the detected values of the vehicular velocity and the steering angular displacement and a target vehicular dynamic model;

a rear tire wheel steering angular displacement command value calculating section that calculates a rear tire wheel steering angular displacement command value according to the detected values of the vehicular velocity and the steering angular displacement, the target vehicular dynamical variables, the tire information, and a previously measured controlled vehicular dynamic model; and

a rear tire wheel steering angular displacement controlling section that controls an actuation of the rear tire wheel steering angular displacement actuator to make the rear tire wheel steering angular displacement command value coincident with an actual rear tire wheel steering angular displacement.

2. A vehicular dynamic controlling apparatus as claimed in claim 1, wherein the target vehicular dynamical variable calculating section further includes:

a determinator to determine a plurality of coefficients on the target vehicular dynamical variables on the basis of the estimated value of the yaw rate gain and the tire information and wherein the target vehicular dynamical variable calculating section calculates the target dynamical variables in accordance with the detected values of the vehicular velocity and steering angular displacement and the target vehicular dynamic model on which the determined coefficients are reflected.

3. A vehicular dynamic controlling apparatus as claimed in claim 1, further comprising:

a road surface frictional coefficient estimator to estimate a frictional coefficient of a road surface on which the vehicle is running and wherein the tire information calculating section calculates the tire information related to the vehicular dynamic information on the basis of an estimated value of the road surface frictional coefficient, the respective braking forces applied to the respectively corresponding tire wheels, and the previously measured tire data.

4. A vehicular dynamic controlling apparatus as claimed in claim 1, further comprising:

a road surface frictional coefficient estimator to estimate a frictional coefficient of a road surface on which the vehicle is running and wherein the target dynamical variable calculating section includes;

a determinator to determine the plurality of coefficients to the target vehicular dynamical variables on the basis of detected value of the road surface frictional coefficient, an estimated value of the yaw rate gain, and the tire information; and

wherein the target vehicular dynamical variable calculating section calculates the target vehicular dynamical variables on the basis of the target vehicular dynamic model on which the determined coefficients are reflected and the detected values of the vehicular velocity and the steering angular displacement.

5. A vehicular dynamic controlling apparatus as claimed in claim 1, further comprising:

a road surface frictional coefficient estimator to estimate a frictional coefficient of a road surface on which the vehicle is running; and

wherein the tire information calculating section includes a tire maximum cornering force calculator to calculate a maximum cornering force of each tire wheel using a predetermined circle of friction equation in accordance with an estimated value of the road surface frictional coefficient, the brake force applied to each tire wheel, and a maximum acceleration at a detected value of the road surface frictional coefficient.

6. A vehicular dynamic controlling apparatus as claimed in claim 1, further comprising:

a road surface frictional coefficient estimator to estimate a frictional coefficient of a road surface on which the vehicle is running; and

wherein the tire information calculating section includes a tire maximum cornering force calculator to calculate a maximum cornering force of each tire using a predetermined ellipse equation, the brake force applied to each of the tire wheels, each tire wheel load, a maximum acceleration on an estimated value of the road surface frictional coefficient, a ratio between a previously measured maximum longitudinal force and a lateral force.

7. A vehicular dynamic controlling apparatus as claimed in claim 6, wherein the yaw rate gain estimating section calculates the vehicular yaw rate gain in a steady state as follows:

Y_G=ψ

/θ

s, wherein ψ

denotes the detected yaw rate and θ

s denotes the detected steering angular displacement.

8. A vehicular dynamic controlling apparatus as claimed in claim 7, wherein the target yaw rate gain setting section sets the target value of the yaw rate gain in the steady state as follows:

Y_GT=V/{NL(1+AV²)}, wherein V denotes the detected vehicular velocity, N denotes a steering ratio of the vehicle, L denotes a wheel base, and A denotes a stability factor of the vehicle.

9. A vehicular dynamic controlling apparatus as claimed in claim 8, wherein the braking force distributing section includes:

a deviation calculator to calculate the deviation between the estimated value of the yaw rate gain in the steady state Y_G and the target value of the yaw rate gain in the steady state Y_GT;

a brake command value calculator to calculate the brake command value Brkcom for each tire wheel according to the deviation as follows;

Brkcom=ErrI×

BrkI+ErrP×

BrkP, wherein ErrI denotes an integration value of the deviation, BrkI denotes an absolute value of the deviation, ErrP denotes a deviation variable, and BrkP denotes a proportional gain; and

a brake command value outputting section that outputs the calculated brake command value Brkcom to the brake pressure controlling section to apply the brake for each rear tire wheel when Brkcom>

0 and to apply the brake for each front tire wheel when Brkcom<

0.

10. A vehicular dynamic controlling apparatus as claimed in claim 9, wherein the tire wheel information calculating section calculates front and rear tire maximum cornering forces C_F and C_R as follows:

C_F (or_R)max={gmax·

μ

_H·

M_F(or _R)·

f_Ty²}·

γ

²y}, wherein gmax denotes a longitudinal acceleration which is enabled to be generated from either the rear or front tires when the detected road surface frictional coefficient, μ

_H denotes an estimated road surface frictional coefficient, M_F (or _R) denotes a wheel load of the front or rear tires, f_Ty denotes a driving force or braking force, γ

y denotes the ratio of the maximum lateral force to the maximum longitudinal force that the corresponding tire can generate.

11. A vehicular dynamic controlling apparatus as claimed in claim 10, wherein the target vehicular dynamic variable calculating section calculates a yaw angular acceleration ddψ

_M and yaw angular velocity dψ

_M as the target vehicular dynamical variables as follows;

12. A vehicular dynamic controlling apparatus as claimed in claim 11, wherein the rear tire wheel steering angular displacement command value calculating section calculates the rear tire wheel angular displacement command value δ

_RC from the target yaw angular acceleration and velocity ddψ

_M and dψ

_M, the detected values of the steering angular displacement θ and

the vehicular velocity ν

, and the previously measured controlled vehicular dynamic model as follows;

13. A vehicular dynamic controlling apparatus as claimed in claim 12, wherein a limiter is provided in the rear tire wheel steering angular displacement command value calculating section for each of the cornering forces C_FS and C_RS as follows:

If C_FS<

C_FMAX;

C_FS=C_FS, if C_FS≧

C_FMAX;

C_RS<

C_RMAX;

C_RS=C_RS, and if C_RS≧

C_RMAX;

C_RS=C_RMAX.

14. A vehicular dynamic controlling apparatus comprising:

vehicular velocity sensing means for detecting a vehicular velocity;

steering angular displacement sensing means for detecting a steering angular displacement of a vehicular steering wheel;

yaw rate sensing means for detecting a vehicular yaw rate;

yaw rate gain estimating means for estimating a vehicular yaw rate gain from detected values of the vehicular velocity, the yaw rate, and the steering angular displacement;

target yaw rate gain setting means for setting a target value of the yaw rate gain;

brake force distribution controlling means for calculating a brake force command value for each of vehicular front left and right and rear left and right tire wheels to reduce a deviation between an estimated value of the yaw rate gain and the target value thereof;

brake pressure controlling means for controlling a brake pressure to be applied to each of the tire wheels in accordance with the brake force command value for each tire wheel;

tire information calculating means for calculating a tire information related to a vehicular dynamic information on the basis of the brake force command value for each tire wheel individually and previously measured tire data;

rear tire wheel steering actuating means for actuating the rear tire wheels to be steered;

target vehicular dynamical variable calculating means for calculating target vehicular dynamical variables on the basis of the detected values of the vehicular velocity and the steering angular displacement and a target vehicular dynamic model;

rear tire wheel steering angular displacement command value calculating means for calculating a rear tire wheel steering angular displacement command value according to the detected values of the vehicular velocity and the steering angular displacement, the target vehicular dynamical variables, the tire information, and a previously measured controlled vehicular dynamic model; and

rear tire wheel steering angular displacement controlling means for controlling an actuation of the rear tire wheel steering angular displacement actuator to make the rear tire wheel steering angular displacement command value coincident with an actual rear tire wheel steering angular displacement.

15. A vehicular dynamic controlling method comprising:

detecting a vehicular velocity;

detecting a steering angular displacement of a vehicular steering wheel;

detecting a vehicular yaw rate;

estimating a vehicular yaw rate gain from detected values of the vehicular velocity, the yaw rate, and the steering angular displacement;

setting a target value of the yaw rate gain;

calculating a brake force command value for each of vehicular front left and right and rear left and right tire wheels to reduce a deviation between an estimated value of the yaw rate gain and the target value thereof;

controlling a brake pressure to be applied to each of the tire wheels in accordance with the brake force command value for each tire wheel;

calculating a tire information related to a vehicular dynamic information on the basis of the brake force command value for each tire wheel individually and previously measured tire data;

calculating target vehicular dynamical variables on the basis of the detected values of the vehicular velocity and the steering angular displacement and a target vehicular dynamic model;

calculating a rear tire wheel steering angular displacement command value according to the detected values of the vehicular velocity and the steering angular displacement, the target vehicular dynamical variables, the tire information, and a previously measured controlled vehicular dynamic model; and

controlling an actuation of a rear tire wheel steering angular displacement actuator to make the rear tire wheel steering angular displacement command value coincident with an actual rear tire wheel steering angular displacement.

16. A vehicular dynamic controlling apparatus comprising:

a vehicular velocity sensor to detect a vehicular velocity;

a steering angular displacement sensor to detect a steering angular displacement of a vehicular steering wheel;

a yaw rate sensor to detect a vehicular yaw rate;

a yaw rate gain estimating section that estimates a vehicular yaw rate gain from detected values of the vehicular velocity, the yaw rate, and the steering angular displacement;

a target yaw rate gain setting section that sets a target value of the yaw rate gain;

a brake force distribution controlling section that calculates a brake force command value for each of vehicular front left and right and rear left and right tire wheels to reduce a deviation between an estimated value of the yaw rate gain and the target value thereof;

a brake pressure controlling section that controls a brake pressure to be applied to each tire wheel in accordance with the brake force command value for each tire wheel;

a tire information calculating section that calculates a tire information related to a vehicular dynamic information on the basis of the brake force command value for each tire wheel individually and previously measured tire data;

a rear tire wheel steering actuator to be enabled to actuate the rear tire wheels to be steered;

a target vehicular dynamic variable calculating section that calculates target vehicular dynamical variables on the basis of the detected values of the vehicular velocity and the steering angular displacement and a target vehicular dynamic model;

a rear tire wheel steering angular displacement command value calculating section that calculates a rear tire wheel steering angular displacement command value according to the detected values of the vehicular velocity and the steering angular displacement, the target vehicular dynamical variables, the tire information, and a previously measured controlled vehicular dynamic model, and wherein said rear tire wheel steering angular displacement command value is affected by the brake force for each tire wheel; and

a rear tire wheel steering angular displacement controlling section that controls an actuation of the rear tire wheel steering angular displacement command value coincident with an actual rear tire wheel steering angular displacement.