Vehicle with an antilock controller

• US 5,316,379 A
• Filed: 06/02/1993
• Issued: 05/31/1994
• Est. Priority Date: 11/29/1990
• Status: Expired due to Term

• Current Assignee: Robert Bosch GmbH
• Original Assignee: Robert Bosch GmbH
• Inventors: Heess, Gerhard, Becker, Rolf, Mergenthaler, Rolf-Hermann, Belzner, Ulrich
• Primary Examiner(s): Oberleitner, Robert J.
• Assistant Examiner(s): BALLATO, JOSIE
• Application Number:
  US08/071,197
• Time in Patent Office: 363 Days
• Field of Search: 303/93, 303/95, 303/100, 180/142, 180/97.1, 280/91, 364/424.05, 364/426.02
• US Class Current: 303/140
• CPC Class Codes: B60T 2201/16 Curve braking control, e.g. turn control within ABS control algorithm
• CPC Class Codes: B60T 2260/022 Rear-wheel steering; Four-wheel steering
• CPC Class Codes: B60T 2260/024 Yawing moment compensation during mu-split braking
• 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: B60T 8/1764 Regulation during travel on surface with different coefficients of friction, e.g. between left and right sides, mu-split or between front and rear
• CPC Class Codes: B62D 6/003 in order to control vehicle yaw movement, i.e. around a vertical axis B62D6/007 takes precedence
• 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

System for controlling yawing moment in a vehicle equipped with ABS and rear wheel steering includes a controller which generates a compensation steering angle for the rear wheels based on the difference between brake pressures at the front wheels. The difference is filtered so that the angle is zero up to a minimum pressure threshold and thereafter consists of a constant portion added to a variable portion which decreases with time. The compensation steering angle so generated may be modified by a correction factor dependent on the transverse acceleration of the vehicle and a further correction factor dependent on the velocity.

Claims

1. System for controlling yawing moment in a vehicle equipped with front wheel steering, rear wheel steering, and ABS control for individual wheels on at least one axle, said yawing moment being caused by different coefficients of friction on opposite sides of the vehicle during ABS control, said front and rear wheel steering being characterized by respective steering angles, said system comprising

means for determining a brake pressure P at individually controlled wheels on one axle on opposite sides of the vehicle during ABS control,

means for determining a difference Δ

P between said pressures P on opposite sides of the vehicle,

means for generating a compensation steering angle δ

dependent upon said difference Δ

P, said angle δ

being zero for said difference Δ

P up to threshold and thereafter consisting of a constant portion depending upon said difference Δ

P added to a variable portion depending upon said difference Δ

P, said variable portion decreasing to zero in a given time, and

means for adjusting at least one of said front and rear wheel steering in dependence upon said compensation steering angle δ

.

2. System according to claim 1, wherein said means for generating said compensation steering angle decreases said variable portion according to an exponential curve.

3. Vehicle according to claim 1 wherein said means for determining brake pressures measures said brake pressures.

4. System according to claim 1 further comprising a decay filter for filtering an input value based on the wheel brake pressures to produce an output value such that in the case of falling brake pressure the output value does not follow the input value fed to the decay filter in an initial phase, and that thereafter the output value follows the input value.

5. System according to claim 4 further comprising a prefilter having an input value based on the determined brake pressures and an output value which serves as said input value for the decay filter and containing a variable limitation on a rise of the output value of the prefilter, the variable limitation being raised from a given initial value to a maximum value whenever a change of the input value of the prefilter of the same sign persists over a period of time.

6. System according to claim 1 further comprising means for determining a vehicle speed and means for correcting the compensation steering angle δ

by a correction factor K_VX depending on the vehicle speed, said factor K_VX being 0 below a lower speed limit and above said limit increasing to 1 at an upper speed limit and remaining at 1 with further increase in velocity.

7. System as in claim 1 further comprising

means for determining the transverse acceleration b_y of the Vehicle,

a correcting apparatus for determining a correction factor which is 1 in the range of said transverse acceleration b_y below a lower acceleration limit and diminishes from 1 to 0 between said lower acceleration limit and an upper acceleration limit, and

means for modifying the compensation steering angle δ

with the correction factor.

8. System as in claim 7 wherein said correcting apparatus is followed by a filtering apparatus whose output magnitude K_by rapidly follows b_y in the case of increasing b_y magnitude, and in the case of decreasing b_y magnitude follows b_y Comparatively slowly, and that the output magnitude K_by is multiplied with the steering angle δ

.

9. System as in claim 8 further comprising means for determining said front and rear wheel steering angles and means for determining a vehicle speed, the transverse acceleration b_y being estimated from the steering angles and the vehicle speed.

10. System as in claim 7 wherein said transverse acceleration b_y is measured.

11. System as in claim 7 further comprising means for determining said front and rear wheel steering angles and means for determining vehicle speed, the transverse acceleration b_y being estimated from the steering angles and the vehicle speed.

12. System for controlling yawing moment in a vehicle equipped with front wheel steering, rear wheel steering, and ABS control for individual wheels on at least one axle, said yawing moment being caused by different coefficients of friction on opposite sides of the vehicle during ABS control, said front and rear steering being characterized by respective steering angles δ

_v and δ

_H, said system comprising

means for determining a transverse acceleration b_y of the vehicle,

correcting means for determining a correcting factor which is 1 in the range of said transverse acceleration b_y below a lower acceleration limit and diminishes from 1 to 0 between said lower acceleration limit and an upper acceleration limit, and

means for modifying at least one of said steering angles δ

_v and δ

_H with said correction factor to generate a compensation steering angle δ

_GMK, and

means for controlling the respective at least one of said front and rear wheel steering in dependence upon said compensation steering angle δ

_GMK.