Boots – shoes – and leggings
Patent
1992-05-27
1994-12-06
Black, Thomas G.
Boots, shoes, and leggings
303 93, 303108, B60T 832, B60T 864
Patent
active
053716779
DESCRIPTION:
BRIEF SUMMARY
PRIOR ART
The slip angles of the wheels or of the axles of a braked motor vehicle are important variables for the vehicle dynamics control of a motor vehicle. This also applies to the cornering forces on the individual wheels. The two variables can be measured directly or determined only with difficulty.
SUMMARY OF THE INVENTION
The invention proposes an estimate of the above mentioned two variables, i.e., the slip angles and the cornering forces there being included in the estimate measured variables which are required in any case for vehicle dynamics control, and are therefore measured.
The present invention generally provides a method for increasing the controllability of a wheeled vehicle having a dynamic drive control system for controlling at least the brake pressure of the wheels, and including the steps of determining slip angle values .alpha..sub.i, where i=1, . . . 4 and indicates the respective vehicle wheel, and applying the determined slip angle values .alpha..sub.i to the dynamic drive control system to improve the vehicle control; and wherein the step of determining the slip angle values .alpha..sub.i comprises: determining respective wheel speeds V.sub.Ri, the steering angle .delta., the vehicle yaw rate .rho. and respective wheel brake cylinder pressures P.sub.Ri ; calculating braking forces F.sub.Bi from the wheel brake pressures P.sub.Ri according to the equation ##EQU1## where .theta.R is the amount of inertia of the wheel, C.sub.Pi is the braking ratio, and R is the radius of the wheel; determining the longitudinal vehicle speed V.sub.L from the wheel speeds V.sub.Ri and from the deceleration of the vehicle; estimating the vehicle transverse speed V.sub.q from the determined values for .delta..sub.i and .rho. using a Kalman Filter; estimating the attitude angles .beta..sub.v and .beta..sub.H from the estimated value V.sub.q of the vehicle transverse speed V.sub.q, according to the relationships ##EQU2## where V and H indicate the front and rear, respectively, and where 1.sub.1 and 1.sub.2 are the respective lengths of the vehicle axles from the vehicle center of gravity; and determining the slip angles .alpha..sub.i, using the estimated attitude angle values .beta..sub.v and .beta..sub.H and values .delta.E.sub.i corresponding the respective elastic steering angle values, according to the relationships
According to the preferred embodiment of the invention at least the wheel speeds V.sub.Ri, the steering angle .delta. and the yaw rate .rho. are measured or determined from measured values of the master brake cylinder pressure. The wheel brake cylinder pressures P.sub.Ri maybe measured. Moreover, preferably the cornering forces F.sub.si on the respective wheels are determined using the estimated attitude angle values .beta..sub.v and .beta..sub.H and the steering angle .delta. and the determined cornering forces F.sub.si are applied to the dynamic drive control system to further improve the controllability of the vehicle.
BRIEF DESCRIPTION OF THE DRAWINGS
FIGS. 1a and 1b are simplified vehicle models used to explain the present invention.
FIGS. 2a, 2b and 3 are further diagrams used in explaining the present invention.
FIGS. 4-7 show a comparison between measured and estimated slip angles of a specific vehicle for various driving maneuvers and different surfaces.
FIG. 8 shows the relationship between the slip angle and the lateral force of a vehicle.
FIG. 9 shows a group of curves illustrating the relationship between the actual and simulated vehicle speed and between the actual and simulated yaw angular velocity when the slip angle is in the non-linear region of the lateral force/slip curve of FIG. 8.
FIG. 10 is a curve illustrating how the difference between the measured and simulated yaw rates can be used, according to a modification of the method according to the invention, to enable to determination of the tire normal forces.
FIG. 11 is a block diagram showing the structure of a slip stiffness controller.
FIG. 12 contains curves showing a comparison between measured and simul
REFERENCES:
patent: 4779696 (1988-10-01), Harada et al.
patent: 4794539 (1988-12-01), Wallentowitz et al.
patent: 4809181 (1989-02-01), Ito et al.
patent: 4862368 (1989-08-01), Kost et al.
patent: 5001636 (1991-03-01), Shiraishi et al.
patent: 5040115 (1991-08-01), Fukushima et al.
Ehret Thomas
Hartmann Uwe
Lutz Albert
Black Thomas G.
Robert & Bosch GmbH
Walker Tyrone V.
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