Data processing: vehicles – navigation – and relative location – Vehicle control – guidance – operation – or indication – Indication or control of braking – acceleration – or deceleration
Reexamination Certificate
1999-12-22
2001-07-24
Cuchlinski, Jr., William A. (Department: 3661)
Data processing: vehicles, navigation, and relative location
Vehicle control, guidance, operation, or indication
Indication or control of braking, acceleration, or deceleration
C701S077000, C303S140000, C303S146000, C180S197000
Reexamination Certificate
active
06266601
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a device for controlling a running behavior of vehicles, and more particularly, to a device for conducting such a control of a four wheeled vehicle based upon a mathematical tire model simulating the performance of longitudinal and lateral forces vs. slip ratio of the tire of each wheel, with a compensation for a malfunction of a brake system.
2. Description of the Prior Art
It is known in the art that the tires of the wheels of vehicles such as automobiles generally exhibit a performance such as exemplarily shown in the map of
FIG. 7
with respect to the relationship between the longitudinal or lateral force and the slip ratio. Of course, the actual performance of each particular tire differs from the shown performance in the shape of the curves as well as in the magnitude of the scales according to its tread pattern and respective operational conditions such as a road surface condition, etc.
Further, it is also known in the art that such a performance between the longitudinal or lateral force and the slip ratio of the tires of wheels of vehicles can be mathematically simulated by the following equations:
Ftxi
=
ξ
i
2
Ks
1
-
Si
Si
-
μ
Wi
cos
θ
i
(
1
-
3
ξ
i
2
+
2
ξ
i
3
)
(
1
)
Ftyi
=
ξ
i
2
Kb
tan
β
i
1
-
SAi
-
μ
Wi
sin
θ
i
(
1
-
3
ξ
i
2
+
2
ξ
i
3
)
(
2
)
wherein, generalizing by i such suffixes as fr, fl, rr and rl indicating the pertinency to front right, front left, rear right and rear left wheels of a common four wheeled vehicle each bearing the tire, Ftxi and Ftyi are the longitudinal and lateral components of a force Fti acting at a tire (wheel) as illustrated in
FIG. 8
, and 0 i is the angle between Fti and Ftxi, Si is a slip ratio of the tire defined as below by equation 5, and other parameters are as defined by the following:
Si
=
u
-
R
ϖ
u
(
5
)
wherein u is vehicle speed at the tire, R is radius of the tire, and &ohgr; is angular speed of the tire (−∞<Si≦1.0)
cos
θ
i
=
Si
λ
i
(
6
)
sin
θ
i
=
Kb
tan
β
i
Ks
λ
i
(
7
)
λ
i
=
Si
2
+
Kb
2
tan
2
β
i
Ks
2
(
8
)
ξ
i
=
1
-
Ks
λ
i
3
μ
Wi
(
1
-
Si
)
(
9
)
wherein &bgr;i is slip angle of the wheel, Wi is vertical load on each wheel, Kb is the inclination at &bgr;i=0 of a curve of the slip angle &bgr;i vs. the lateral force Ftyi such as shown in FIG.
9
and Ks is the inclination at Si=0 of a curve of the slip angle Si vs. the longitudinal force Ftxi such as shown in FIG.
10
.
The above equations are mathematical analyses of the relationships among such parameters as the longitudinal and lateral forces, the slip ratio, the slip angle, the vertical load and the friction coefficient with respect to each single tire. On the other hand, the running behavior of a four wheeled vehicles is a matter of interrelations among such respective performances of the four wheels.
FIG. 11
shows an example of the yaw moment applied to the vehicle body of a four wheeled vehicle by a braking of each of the four wheels when the vehicle is running out of a straight course.
It would be contemplated to apply the above mathematical analyses to the running behavior control of four wheeled vehicles by preparing certain maps of relationships between or among each two or three of those parameters. However, if a four wheeled vehicle is mathematically controlled of its running behavior based upon a mathematical tire model such as expressed by the above-mentioned equations 1-9, since at least 11 parameters will be incorporated in the mathematical control calculations even when only one of the front and rear pairs of the wheels are controlled about their braking, only a very rough discrete points simulation would be available even by using the most modern microcomputers employable for an automobile running behavior control from the view point of the convenience of construction and economy.
In view of such an estrangement between the self-closed mathematical analyses applicable only to the performance of a single tire and the complicated interrelations of the performances of the pairs of front and rear wheels in the actual running behavior controls of four wheeled vehicles, our colleagues have proposed in a co-pending U.S. patent application Ser. No. 09/282,416 filed by the same assignee as the present assignee to provide a device for controlling a running behavior of four wheeled vehicles which can utilize a self-closed mathematical performance analysis of a single wheel tire such as described above effectively for a running behavior control of four wheeled vehicles even by using a microcomputer of a limited capacity.
According to the prior proposition, the device for controlling a running behavior of a vehicle based upon a force-slip performance of a tire, the vehicle having a vehicle body, a pair of front wheels and a pair of rear wheels, and brake means for selectively applying a controlled braking force to at least either the front pair or the rear pair of the wheels bearing the tires, comprises:
first means for cyclically calculating by a minute cycle period longitudinal force and lateral force of each of the at least either the front pair or the rear pair of the wheels in reference to slip ratio thereof according to a mathematical tire model of a relationship therebetween, so as to obtain a first longitudinal force and a first lateral force corresponding to a first slip ratio and a second longitudinal force and a second lateral force corresponding to zero slip ratio;
second means for cyclically calculating by the minute cycle period longitudinal force, lateral force and yaw moment of the vehicle body based upon the longitudinal forces and the lateral forces of the at least either the front pair or the rear pair of the wheels, so as to obtain a first longitudinal force, a first lateral force and a first yaw moment of the vehicle body corresponding to the first longitudinal forces and the first lateral forces of the at least either the front pair or the rear pair of the wheels and a second longitudinal force, a second lateral force and a second yaw moment of the vehicle body corresponding to the second longitudinal forces and the second lateral forces of the at least either the front pair or the rear pair of the wheels;
third means for cyclically modifying by the minute cycle period the second longitudinal force, the second lateral force and the second yaw moment of the vehicle body calculated by the second means with a longitudinal force, a lateral force and a yaw moment corresponding to an output of an outside running behavior controller, so as to obtain a nominal longitudinal force, a nominal lateral force and a nominal yaw moment, respectively;
fourth means for cyclically calculating by the minute cycle period a difference between the nominal longitudinal force and the first longitudinal force, a difference between the nominal lateral force and the first lateral force and a difference between the nominal yaw moment and the first yaw moment;
fifth means for cyclically calculating by the minute cycle period differentials of the longitudinal and lateral forces of each of the at least either the front pair or the rear pair of the wheels on the basis of the slip ratio thereof according to the mathematical tire model;
sixth means for cyclically calculating by the minute cycle period different
Hattori Yoshikazu
Soga Masayuki
Cuchlinski Jr. William A.
Donnelly Arthur D.
Oliff & Berridg,e PLC
Toyota Jidosha & Kabushiki Kaisha
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