Method for determining the slip angles and/or the cornering forces of a braked vehicle

• US 5,371,677 A
• Filed: 05/27/1992
• Issued: 12/06/1994
• Est. Priority Date: 09/28/1990
• Status: Expired due to Term

• Current Assignee: Robert Bosch GmbH
• Original Assignee: Robert Bosch GmbH
• Inventors: Lutz, Albert, Hartmann, Uwe, Ehret, Thomas
• Primary Examiner(s): Black, Thomas G.
• Assistant Examiner(s): Walker, Tyrone V.
• Application Number:
  US07/859,394
• Time in Patent Office: 923 Days
• Field of Search: 364/426.01, 364/426.02, 303/93, 303/108, 303/100
• US Class Current: 701/72
• CPC Class Codes: B60T 2230/02 Side slip angle, attitude angle, floating angle, drift angle
• CPC Class Codes: B60T 2270/86 Optimizing braking by using ESP vehicle or tire model
• CPC Class Codes: B60T 8/17552 responsive to the tire sideslip angle or the vehicle body slip angle
• 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

Abstract

A method is described for determining the slip angles α_i and/or the cornering forces F_S of a braked vehicle. Starting from a simplified vehicle model and using the wheel speeds V_Ri, the steering angle β, the yaw rate φ and the master brake cylinder pressure P_HB2 or the wheel brake pressure P_i as measured variables, the desired variables are determined as estimated variables.

Claims

1. A method for increasing the controllability of a wheeled vehicle having a dynamic drive control system for controlling at least the brake pressure applied to the wheels, said method including the steps of:

determining the respective the wheel speeds V_Ri, where i=1, . . . 4 and indicates the respective vehicle wheel, the steering angle δ

, the yaw rate ρ and

the respective wheel brake cylinder pressures P_Ri ;

calculating the braking forces F_Bi from the wheel brake pressures P_Ri according the equation ##EQU29## where θ

R is the amount of inertia of the wheel, C_Pi is the braking ratio, and R is the radius of the wheel;

determining the longitudinal vehicle speed V_L from the wheel speeds V_Ri and from the deceleration of the vehicle;

estimating the vehicle transverse speed V_q from the determined values for δ and

ρ

using a Kalman Filter;

estimating the attitude angles β

_v and β

_v from the estimated value V_q of said vehicle transverse speed V_q, according to the relationships ##EQU30## where V and H indicate the front and rear, respectively, and where l₁ and l₂ are the respective lengths of the vehicle axles from the vehicle center of gravity; and

determining the respective elastic steering angle values δ

E_i from the calculated braking forces F_Bi ;

determining the slip angles α

_i, using said estimated attitude angle values β

_V and β

_H and said respective elastic steering angle values δ

E_i, according to the relationships

space="preserve" listing-type="equation">α

.sub. =δ

-β

.sub. V -δ

.sub.E1

space="preserve" listing-type="equation">α

.sub.2 =δ

-β

.sub.V -δ

.sub.E2

space="preserve" listing-type="equation">α

.sub.3 =β

.sub.H -δ

.sub.E3

space="preserve" listing-type="equation">α

.sub.4 =β

.sub.H -δ

.sub.E4

and,

applying the determined slip angles α

_i to the dynamic drive control system and utilizing the values α

_i for controlling the brake pressure applied to the wheels.

2. Method according to claim 1, further comprising, additionally determining the tire normal forces N_i.

3. The method according to claim 1 wherein at least the wheel speeds V_Ri, the steering angle δ

and the yaw rate ρ

are measured.

4. The method according to claim 3 wherein the wheel brake cylinder pressures P_Ri are measured.

5. The method according to claim 3 wherein the master brake cylinder pressure is measured and the respective wheel brake pressures P_Ri are determined from the measured master brake cylinder pressure.

6. The method according to claim 1 further comprising determining the cornering force F_si on the respective wheels using the estimated attitude angle values β

_V and β

_H and the steering angle δ

; and

applying the cornering forces F_si to the dynamic drive control system to further improve the controllability of the vehicle.