Data processing: vehicles – navigation – and relative location – Vehicle control – guidance – operation – or indication – Vehicle subsystem or accessory control
Reexamination Certificate
2000-01-07
2002-03-19
Nguyen, Tan (Department: 3661)
Data processing: vehicles, navigation, and relative location
Vehicle control, guidance, operation, or indication
Vehicle subsystem or accessory control
C701S075000, C701S083000, C303S140000
Reexamination Certificate
active
06360150
ABSTRACT:
TECHNICAL FIELD
The invention relates to a vehicle yaw dynamics control system, capable of optimally controlling a vehicle yaw momentum during steering operation by applying a yawing moment to the vehicle by means of a control apparatus which performs a driving-force distribution control and/or a braking-force control for each of road wheels.
BACKGROUND ART
A conventional vehicle yaw dynamics control system has been disclosed in Japanese Patent Provisional Publication No. 5-262156.
The conventional system includes a driving-force distribution adjusting mechanism which distributes a driving force output from an engine of an automotive vehicle into left and right road wheels and adjusts torque-distribution between the left and right road wheels, a yaw rate sensor which detects an actual yaw rate of the automotive vehicle, a target yaw rate arithmetic-calculation means which arithmetically calculates a target yaw rate on the basis of input information, namely a steer-angle information data signal from a steer angle sensor and a vehicle-speed information data signal from a vehicle speed sensor, and a control means which controls the operation of the driving-force distribution adjusting mechanism. The control means is constructed in a manner so as to set a controlled hydraulic pressure applied to the driving-force distribution adjusting mechanism, while performing feed-back control so that the actual yaw rate is approached to the target yaw rate.
The previously-described conventional system has feedback-controlled so that the actual yaw rate is approached or adjusted to the target yaw rate. However, it is a somewhat delay time from the occurrence of a yaw moment applied to the vehicle after operation of the driving-force distribution adjusting mechanism to a time when the yaw moment generated is detected as a yaw rate by means of the yaw rate sensor. Thus, in performing the feedback control based on the actual yaw rate detected in a way as discussed above, as shown in FIG.
22
(
b
), there is a risk or possibility of control delay.
Additionally, a differential calculus is made to obtain a controlled variable, thus resulting in increased oscillations and noises. In cooperation with the previously-noted control delay, as a result of the yaw dynamics control, the characteristic curve tends to oscillate, as shown in FIG.
23
.
There is the problem that the driver feels uncomfortable in the presence of the above-mentioned undesired control delay or oscillations (hunting).
In addition, a yaw moment, acting on the vehicle, is dependent on a side force acting at a tire. The side force varies depending on a friction coefficient of a road surface (which will be hereinafter referred to as a “road-surface &mgr;”). The prior-art system could not execute a high-precision yaw control in due consideration of the road-surface &mgr;.
DISCLOSURE OF THE INVENTION
It is, therefore, in view of the previously-described disadvantages of the prior art, in controlling a yaw momentum acting on the vehicle, a principal object of the present invention to provide a vehicle yaw dynamics control system which is capable of enhancing the quality of yaw control without giving a driver an uncomfortable feeling, while eliminating the problem of the control delay or the occurrence of hunting during the yaw control. Furthermore, it is another object of the invention is to attain the previously-noted principal object, in spite of a low-cost yaw dynamics control system. It is a still further object of the invention is to highly enhance the quality of yaw control by performing the yaw control depending on the road-surface &mgr;.
In order to accomplish the aforementioned objects, as shown for example in the block diagram of
FIG. 1
, a vehicle yaw dynamics control system of the present invention, a yaw moment generating mechanism a which produces a yawing motion at the vehicle, a vehicle behavior detection means b which detects a vehicle behavior, an actual yaw moment detection means c which is included in the vehicle behavior detection means b and detects an actual yaw moment acting on the vehicle, a target yaw moment arithmetic-calculation means d which arithmetically calculates a target yaw moment necessary for a current vehicle behavior on the basis of the latest up-to-date input information being input from the vehicle behavior detection means b, and an operating command means e which operates the yaw moment generating mechanism to output a yaw moment equivalent to the difference between the target yaw moment and the actual yaw moment.
According to another aspect of the invention, in the vehicle yaw dynamics control system, the previously-noted vehicle behavior detection means b includes a side-force plus longitudinal-force detection means which detects a side force acting on each of road wheels and a longitudinal force acting on each of the road wheels, and the previously-noted actual yaw moment detection means a includes a means for arithmetically calculating the actual yaw moment on the basis of an input from the side-force plus longitudinal-force detection means.
According to aspect of the invention, in the vehicle yaw dynamics control system, the previously-noted vehicle behavior detection means b includes a yaw rate sensor which detects a yaw rate of the vehicle, and the previously-noted actual yaw moment detection means c includes a means for arithmetically calculating the actual yaw moment by multiplying a differentiated value of the yaw rate detected with a yaw moment of inertia of the vehicle.
According to another aspect of the invention, in the vehicle yaw dynamics control system, the previously-noted target yaw moment arithmetic-calculation means d includes a means for arithmetically calculating a target yaw rate by a steer angle and a quantity of state of the vehicle, and for arithmetically calculating the target yaw moment by multiplying the a differentiated value of the target yaw rate with a yaw moment of inertia of the vehicle.
According to another aspect of the invention, in the vehicle yaw dynamics control system, the previously-noted target yaw moment arithmetic-calculation means d includes a means for arithmetically calculating the target yaw moment by a quantity of state of each of the road wheels and a target tire characteristic.
According to another aspect of the invention, in the vehicle yaw dynamics control system, the previously-noted target yaw moment arithmetic-calculation means d includes a wheel load arithmetic-calculation means d
1
which arithmetically calculates a wheel load of each of the road wheels, a wheel slip angle arithmetic-calculation means d
2
which arithmetically calculates a slip angle of each of the road wheels, and a wheel braking-force/driving-force arithmetic-calculation means d
3
which arithmetically calculates a wheel braking-force/driving-force, and the quantity of state of each of the road wheels comprises a wheel load, a slip angle, and a braking-force/driving-force.
According to another aspect of the invention, in the vehicle yaw dynamics control system, the previously-noted target yaw moment arithmetic-calculation means d includes a load-transfer arithmetic-calculation means d
11
for arithmetically calculating a load transfer based on lateral acceleration, a slip-angle arithmetic-calculation means d
12
for arithmetically calculating a slip angle of each of the road wheels, and an arithmetic-calculation means d
13
for arithmetically calculating a target side force by only the load transfer and the slip angle of each of the road wheels, from the target tire characteristic, and for arithmetically calculating the target yaw moment on the basis of the target side force.
According to another aspect of the invention, in the vehicle yaw dynamics control system, the previously-noted actual yaw moment detection means c is constructed by a tire quantity-of-state estimation means c
1
for estimating a quantity of state of each of tires of the road wheels, and an arithmetic-calculation means c
2
for arithmetically calculating the yaw moment of the vehicle by an output
Fukushima Naoto
Katsuyama Etsuo
Foley & Lardner
Nguyen Tan
Tran Dalena
Unisia Jecs Corporation
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