Data processing: vehicles – navigation – and relative location – Vehicle control – guidance – operation – or indication
Reexamination Certificate
2001-05-02
2002-12-31
Zanelli, Michael J. (Department: 3661)
Data processing: vehicles, navigation, and relative location
Vehicle control, guidance, operation, or indication
C701S050000, C701S070000, C701S022000, C701S041000, C701S080000, C188S15100A, C188S152000, C033S286000, C033S288000, C033S356000, C033S361000, C180S197000, C180S247000, C180S248000, C180S249000, C303S121000, C303S020000, C303S122000
Reexamination Certificate
active
06502014
ABSTRACT:
TECHNICAL FIELD
The present invention generally relates to vehicle stability control, and more particularly relates to a control circuit for controlling the driving stability of a vehicle in which the input quantities defining the course of the vehicle are input to a vehicle model circuit.
BACKGROUND OF THE INVENTION
The control circuits control the steering behavior of the vehicle, if the vehicle's path does not correspond to the path intended by the driver.
Especially in case of external influences, e.g. different adhesion on wet, icy or dry road sections, side wind and reactions to load alternations, an additional torque is necessary so that the way actually covered by the vehicle corresponds to the way intended by the driver.
Input quantities resulting from the path intended by the driver, e.g. steering wheel angles or speed, are transmitted to a vehicle model circuit which on the basis of said input quantities and parameters typical for the driving behavior of the vehicle, but also on the basis of the characteristics of the environment (coefficient of friction of the road surface and similar) defines a nominal yaw rate being compared with the actually measured yaw rate. The difference between the yaw rates is converted into a yaw torque by means of a so-called yaw torque controller, the yaw torque representing the input quantity of the control circuit.
The control circuit, on the other hand, defines the brake pressure to be applied on the single wheel brakes, if necessary subject to the driver's request to apply a certain brake pressure on the wheel brakes. In addition to the desired braking effect, the brake pressure should create an additional torque on the vehicle supporting the driving behavior of the vehicle in the direction in which the driver intends to steer the vehicle. From this results that the quality of controlling the yaw rate of the vehicle is substantially defined by the quality of the vehicle model circuit which predefines the desired yaw rate on the basis of the input data of the driver.
Different vehicle models can be used in the control circuit which simulate the driving behavior of the vehicle by way of calculation, the different vehicle models being based on simplified assumptions concerning the driving behavior of a vehicle.
A known vehicle model is the so-called linear dynamic single-track model. In this model the driving characteristics of a vehicle are reduced, by way of calculation, to one vehicle model in which the front and rear wheels each are combined in pairs to one wheel being positioned on the longitudinal axis of the vehicle.
The following system equations are valid for a single-track model in a condition representation:
β
.
=
c
11
β
v
-
ψ
.
+
c
12
ψ
.
v
2
+
c
13
δ
v
(
1
)
ψ
..
=
c
21
β
+
c
22
ψ
.
v
+
c
23
δ
(
2
)
&bgr; defining a slip angle, {dot over (&psgr;)} the yaw rate and &dgr; the steering angle.
The model coefficients C
ii
are included in the system equations and formed as follows:
c
11
=
-
c
h
+
c
v
m
c
12
=
c
h
l
h
-
c
v
l
v
m
c
13
=
c
v
m
(
3
)
c
21
=
c
h
l
h
-
c
v
l
v
Θ
c
22
=
c
h
l
h
2
+
c
v
l
v
2
Θ
c
23
=
c
v
l
v
Θ
(
4
)
C
h
and c
v
represent the resulting stiffness determined by the control circuit for controlling the driving stability of the vehicle in consideration of the wheel suspension and steering elasticity on the rear resp. front axle. The values l
h
and l
v
represent the distances of rear and front axle from the vehicle's gravity centre. &THgr; is the yaw moment of inertia of the vehicle, i.e. the moment of inertia of the vehicle around its vertical axis.
The standard parameters for the memorized single-track model which form the basis of the model coefficient c
ii
, are obtained by measurements outside the vehicle on the basis of an off-line parameter identification. The measured controller and sensor quantities of the driving stability control are used for identification. Four speed sensors, one for each wheel, a yaw acceleration meter, a transverse acceleration meter and at least one pressure sensor for the brake pressure generated by the brake pedal are provided on the vehicle in order to detect the vehicle dynamics. The parameters are determined by means of one or more model vehicles, and the “standard parameter set” is memorized in the vehicle model circuit.
During travel, vehicles with standard parameter sets memorized in the vehicle model present erroneous control activation by means of the driving stability control, if the condition quantities on which the model coefficients are based during off-line parameter identification, differ from the actual condition quantities being defined by the individual configuration or equipment of the vehicle. The deviations may range from a mere comfort problem to an impairment of the driving behavior of the vehicle. There is an erroneous control activation by the driving stability control if the individual configuration of the vehicle leads to deviations of the standard parameters memorized in the dynamic single-track model or if the parameters on which the vehicle is based due to its individual configuration are lying outside the control threshold of the standard parameters.
One known solution to the problem is to expand control thresholds in critical areas of the vehicle stability. This leads to functionality and performance losses due to an unnecessary threshold expansion in vehicles with an individual configuration or equipment which is detected by the standard parameters defined in the single-track model and does not prevent reliably the erroneous control activation if there are extreme deviations with regard to the configuration or equipment of a single vehicle.
It is the object of the present invention to provide for a generic control circuit preventing the erroneous control activation. This object is achieved according to the present invention by that at least one of the parameters is varied subject to at least one separately defined measuring quantity.
The invention includes a generic control circuit that is used in such a way that the vehicle model is adapted during operation by the identification of the standard parameters specific to the every single vehicle by means of input quantities which are made available by the vehicle's sensor system. Basis of the invention is the finding, that the individual vehicle due to different configuration or equipment variants, as e.g. tire type (winter tires, summer tires, all-weather-tires), tire size (15″/16″/17″), condition, especially the lateral tire stiffness, changes of the chassis, production tolerances or loading, differs or deviates considerably from a model vehicle or model vehicles which are used for determining the standard parameter set memorized in the single-track model.
One advantageous embodiment of the control circuit is characterized by that a vehicle identification means is foreseen, the output signals of which are transmitted to the vehicle reference model and that the output signals in consideration of individual condition quantities of the vehicle adapt the standard parameters memorized in the vehicle reference model or substitute them by newly built standard parameters.
A further improvement of the control circuit is achieved wherein the vehicle identification means is provided with an identification plausibility means for switching an identification module into active or passive mode subject to the individual input quantities.
Furthermore it is useful to configure the control circuit in such a way that the yaw speed and/or the steering angle and/or the steering angle speed and/or the transverse acceleration and/or the longitudinal acceleration and/or the slip angle speed and/or the wheel speed are the quantities being input.
One advantageous embodiment of the control circuit is characterized by that the deviations are defined by individual input quantities and de
Duis Holger
Endress Ralf
Herrmann Torsten
Jokic Mile
Lüders Ulrich
Continental Teves AG & Co. oHG
Mancho Ronnie
Rader & Fishman & Grauer, PLLC
Zanelli Michael J.
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