Fluid-pressure and analogous brake systems – Speed-controlled – With yaw control
Patent
1994-08-18
1996-01-02
Ballato, Josie A.
Fluid-pressure and analogous brake systems
Speed-controlled
With yaw control
303191, B60K 2816, B60T 832, B60T 824
Patent
active
054802199
DESCRIPTION:
BRIEF SUMMARY
PRIOR ART
The invention relates to a method of controlling vehicle stability by determining a required yaw velocity .omega..sub.so11 based on a steady state required yaw rate .omega..sub.so110. A method for determining .omega..sub.so110 is disclosed in DE 42 29 504, to which U.S. Ser. No. 08/090,837 corresponds. The subject matter of the latter is based on DE 37 31 756, to which U.S. Pat. No. 5,332,300 corresponds.
SUMMARY OF THE INVENTION
The wish of the driver for a change of direction, as well as that for vehicle acceleration or deceleration, is taken into account and weighted. The required value is calculated in such a way that the vehicle reacts rapidly to steering angle changes and then maintains a stable condition which depends on the adhesion coefficient of the road and in which the sideslip angle does not increase further.
The following advantages are achieved by the invention and by the further developments in accordance with the preferred embodiments:
The driver's wish is taken into account in the distribution, of the total available tire force, between longitudinal force and transverse force using v.sub.F, .delta., P.sub.vor, F.sub.ges ;
Calculation of a limit, to ensure vehicle stability, for the required yaw rate with a.sub.Q and v.sub.F ;
Filtering the required yaw rate value for matching to the vehicle's intrinsic dynamics of motion or to change in the vehicle dynamics of motion;
Supporting the incidence motion of the vehicle when the steering angle is increased in order to build up side force more rapidly.
In systems for controlling the dynamics of vehicle motion in order to improve the controllability of the vehicle, it is necessary to fix the parameters to be controlled and then to determine suitable required values for these parameters.
If the vehicle motion is considered in one plane (roadway) and not in three dimensions, the vehicle then has three degrees of freedom, namely longitudinal velocity and transverse velocity and the rotational velocity about the vertical axis (yaw rate). The yaw rate has been found to be a particularly suitable control parameter because it can be measured directly by means of sensors and can be effectively controlled by changing the wheel slip values or the slip angle and, therefore, by the application of yaw moments. The transverse velocity of the vehicle cannot be measured accurately. It can, however, be estimated by a control algorithm (observer) when the yaw rate is known.
The following computational operations are carried out to calculate the required yaw rate value .omega..sub.so11 :
A steady-state required yaw rate, which depends on the steering angle .delta. and on the vehicle longitudinal velocity v.sub.F, is calculated first. ##EQU1##
In this, v.sub.ch is the characteristic vehicle speed with which the amount of the understeer tendency can be fixed, also if need be as a function of the driving condition (driven, freely rolling, braked).
In the case of steady-state travel in a circle, a desired side force F.sub.S,W can now be calculated from the required steady state yaw rate:
The desired longitudinal force F.sub.L,W can be calculated, depending on the accelerator pedal position or brake pedal position, from the measured quantities of admission (master cylinder) pressure P.sub.vor or throttle butterfly angle .alpha..sub.DK. In this, it is assumed that the braking wish or the drive wish corresponds to that for undisturbed straight-line travel at a high coefficient of friction.
The total force desired by the driver can therefore be calculated as a vector sum. ##EQU2##
This desired force is now placed in a relationship with the maximum available force.
First Possibility
The resultant tire forces Fr.sub.i at the individual wheels are known (for example, in accordance with DE 40 30 704-A1) which corresponds to U.S. Ser. No. 07/859,438. The maximum available total force can then be estimated from the sum of all the tire forces. It is achieved when all the force directions are parallel. ##EQU3##
Second Possibility
The total longitudinal force F.
REFERENCES:
patent: 4898431 (1990-02-01), Karnopp et al.
patent: 4939656 (1990-07-01), Hoashi et al.
patent: 5275475 (1994-01-01), Hartmann et al.
patent: 5332300 (1994-07-01), Hartmann et al.
Zomotor, Adam: Fahrwerktechnik: Fahrverhalten pp. 112-116 (1987).
Bosch Automotive Handbook pp. 340-347 (1993).
Ehret Thomas
Erhardt Rainer
Hartmann Uwe
Kost Friedrich
Ruf Wolf-Dieter
Ballato Josie A.
Robert & Bosch GmbH
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