Data processing: vehicles – navigation – and relative location – Vehicle control – guidance – operation – or indication
Reexamination Certificate
2002-11-06
2004-06-01
Cuchlinski, Jr., William A. (Department: 3661)
Data processing: vehicles, navigation, and relative location
Vehicle control, guidance, operation, or indication
C701S036000, C701S072000, C701S082000, C180S197000
Reexamination Certificate
active
06745112
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method for estimating quantities that represent the state of a vehicle, such as the vehicle body sideslip angle.
2. Description if the Related Art
Conventionally, control is known for improving the maneuverability of a vehicle by using the quantities that represent the vehicle state, such as the vehicle body sideslip angle &bgr; (that is, the angle formed between the forward direction of the vehicle and the longitudinal axis of the vehicle) when controlling the state of movement of the vehicle during a turning movement, for example. In this type of control, a method is known wherein, in the case that, for example, the vehicle body sideslip angle &bgr; is used, the yaw rate r detected by a yaw rate sensor (that is, the turn angle speed of the vehicle center of gravity around the axis in the vertical direction), the lateral acceleration G
y
detected by the lateral acceleration sensor (that is, the acceleration or deceleration added in the lateral direction of the vehicle), and the velocity V of the vehicle (vehicle speed) detected by the vehicle velocity sensor are substituted into the following equation 1, which is derived from the equation representing the physical relations of the quantities that represent the state of the movement of the vehicle, and by carrying out integration with respect to time, the vehicle body sideslip angle &bgr; is estimated.
However, in methods in which the results of the detected quantities from each of the sensors are integrated with respect to time, the influence of noise in each of the sensors, the error included in the results of the detected quantities, and the deviations in the calibrations of each of the sensors accumulate, and thus there is the concern that the precision of the estimation of the vehicle body sideslip angle &bgr; deteriorates.
β
=
∫
(
G
y
V
-
r
)
ⅆ
t
Eq
.
1
In response to these problems, the method of estimating the vehicle body sideslip angle and estimating apparatus disclosed, for example, in Japanese Unexamined Patent Application, First Publication, No. Hei 11-78933, is known. In this method, models of a plurality of wheels are introduced, and the vehicle body sideslip angle &bgr; is estimated by switching the model for the wheels depending on, for example, the case that the coefficient of friction of the road surface changes or the various conditions during travel in the critical vicinity of movement of the vehicle (that is, the critical zone in which there is the possibility that the state of movement of the vehicle may become unstable when there is no control of any kind).
However, in the vehicle body sideslip angle estimation method and estimation apparatus according to the example of conventional technology described above, there are the problems that the computation processing of the vehicle body sideslip angle &bgr; becomes complicated, and that the computation load increases.
Furthermore, there are cases in which the estimated value of the vehicle body sideslip angle &bgr; drastically changes due to the timing during which the models of a plurality of wheels are switched, and thus the there is a concern that the drivability will deteriorate.
In consideration of the problems described above, it is an object of the present invention to provide a method of estimating the quantities representing the state of the vehicle that can improve the precision of the estimations of the vehicle body sideslip angle or values related to the vehicle body sideslip angle by a simple and inexpensive method.
SUMMARY OF THE INVENTION
In order to solve the problems and attain the objects described above, a first aspect of the method of estimating quantities that represent the state of the vehicle of the present invention comprises a step of detecting the yaw rate and vehicle speed (for example, step S
02
and step S
06
in the embodiment described below); and a step (for example, step S
02
to step S
03
in the embodiment described below) of calculating three equations which comprises an equation of equilibrium (for example, equation 2 in the embodiment described below) for the force in the lateral direction of the vehicle, an equation of equilibrium (for example, equation 3 in the embodiment described below) for the moment around the vertical axis of the vehicle, and an equation for the physical relationships of the quantities that represent the state of the vehicle movement (for example, equation 4 in the embodiment described below), using the vehicle body sideslip angle, the front wheel cornering power, and the rear wheel cornering power as unknown values.
According to the first aspect of the present invention, the method of estimating the quantities that represent the vehicle state described above, based on an equation of equilibrium for the force in the lateral direction of the vehicle, an equation of equilibrium for the moment around the vertical axis of the vehicle, and an equation for the physical relationships of the quantities that represent the state of the vehicle movement obtained from a predetermined model of the movement of the wheels that describes the yaw movement of the vehicle in, for example, a two wheel model, it is possible to derive simultaneous equations comprising the three unknown quantities of the vehicle body sideslip angle, the front wheel cornering power, or the rear wheel cornering power by setting detected values from each of the sensors to the yaw rate and the vehicle speed. That is, it is possible to estimate the vehicle sideslip angle using a simple method that limits increases in the computing load and has high precision by using the exact number of equations for the number of unknowns to be calculated.
The second aspect of the present invention provides a method of estimating quantities that represent the vehicle state comprises a step (for example, steps
02
and step S
06
in the embodiment described below) of detecting the yaw rate, the lateral acceleration, and the vehicle speed, a step (for example, step S
02
to step S
08
in the embodiment described below) of calculating the velocity of the vehicle in the lateral direction using three equations, an equation of equilibrium for the force in the lateral direction of the vehicle (for example, equation 15 in the embodiment described below), an equation of equilibrium for the moment around a vertical axis of the vehicle (for example, equation 16 in the embodiment described below), and an equation for the physical relationships of the quantities that represent the state of the vehicle movement, using the vehicle speed in the lateral direction, the front wheel cornering power, and the rear wheel cornering power as unknown values, and a step (for example, step S
04
in the embodiment described below) of calculating the vehicle body sideslip angle from the velocity of the vehicle in the lateral direction.
According to the second method of estimating the quantities that represent the state of a vehicle of the present invention, based on an equation of equilibrium for the force in the lateral direction of the vehicle, an equation of equilibrium for the moment around the vertical axis of the vehicle, and an equation for the physical relationships of the quantities that represent the state of the vehicle movement obtained from a predetermined movement model of vehicles that describes the yaw movement of the vehicle in, for example, a two wheel model, it is possible to derive simultaneous equations comprising three unknown quantities that represent the speed of the vehicle in the lateral direction, the front wheel cornering power, and the rear wheel cornering power by setting detected values from each of the sensors to the yaw rate and the vehicle speed. Here, it is possible to estimate the vehicle body sideslip angle using a simple method that limits increases in the computation load while at the same time has a high precision because it is possible to calculate unambiguously the vehicle body sideslip angle from the velocity o
Cuchlinski Jr. William A.
Hernandez Olga
Honda Giken Kogyo Kabushiki Kaisha
Merchant & Gould P.C.
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