Measuring and testing – Instrument proving or calibrating – Speed – velocity – or acceleration
Reexamination Certificate
2000-02-01
2001-07-17
Raevis, Robert (Department: 2856)
Measuring and testing
Instrument proving or calibrating
Speed, velocity, or acceleration
Reexamination Certificate
active
06260405
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a system for detecting an abnormality of a yaw rate sensor for detecting a yaw rate of a vehicle, and a system for detecting an abnormality of a lateral acceleration sensor for detecting a lateral acceleration of the vehicle.
2. Description of the Related Art
To detect the abnormality of the yaw rate sensor, it is a conventional practice to determine that the yaw rate is abnormal when the value detected by the yaw rate sensor exceeds an upper limit value or a lower limit value, and to determine the abnormality of the yaw rate sensor by comparison of the yaw rate presumed from a difference between left and right wheel speeds with the value detected by the yaw rate sensor.
In the technique for determining whether the yaw rate sensor is abnormal based on whether the value detected by the yaw rate sensor exceeds the upper or lower limit value, it is impossible to detect a state in which the neutral point of the yaw rate sensor is normal, but the sensitivity is abnormal. In the technique for determining whether the yaw rate sensor is abnormal by the comparison of the yaw rate presumed from a difference between the left and right wheel speeds with the value detected by the yaw rate sensor, the yaw rate presumed from the difference between the left and right wheel speeds is inaccurate when the vehicle is traveling on a rough road or on a road surface having a low friction coefficient, on which the wheel is liable to slip. For this reason, it is impossible to determine the abnormality of the yaw rate sensor with good accuracy.
SUMMARY OF THE INVENTION
The present invention has been accomplished with such circumstance in view, and it is a first object of the present invention to provide a system for detecting an abnormality of a yaw rate, wherein the abnormality of a yaw rate sensor, including a state in which the neutral point of the yaw rate sensor is normal, but the sensitivity is abnormal, can be detected with good accuracy, irrespective of the situation of a road surface traveled. It is a second object of the present invention to provide a system for detecting an abnormality of a lateral acceleration sensor, wherein the abnormality of the lateral acceleration sensor can be detected with good accuracy, based on the measure enabling the abnormality of the yaw rate sensor to be detected with good accuracy.
To achieve the first object, there is provided a system for detecting an abnormality of a yaw rate sensor, comprising a vehicle speed detecting means for detecting a vehicle speed of a vehicle, a dividing means for dividing the vehicle speed detected by the vehicle speed detecting means by a minimum turning radius of the vehicle, a dividing means for dividing a gravitational acceleration by the vehicle speed detected by the vehicle speed detecting means, a low-select means for selecting a lower one of outputs from both of the dividing means, and an abnormality determining means for determining that a yaw rate sensor is abnormal when the yaw rate detected by the yaw rate sensor exceeds a value selected by the low-select means.
When there is no side-slip of the vehicle, the yaw rate y of the vehicle must be within an obliquely-lined range shown in
FIG. 3
depending upon a limit value of centripetal acceleration of the vehicle, i.e., the gravitational acceleration G and a lower limit value of the radius of turning of the vehicle, i.e., the minimum turning radius R. If the vehicle speed is represented by V, the yaw rate &ggr; of the vehicle capable of being generated must be in a range of &ggr;≦min{(V/R), (G/V)}. Therefore, when the yaw rate &ggr; is in a range which exceeds lower one of a value (V/R) obtained by dividing the vehicle speed V by the minimum radius R of turning of the vehicle and a value (G/V) obtained by dividing the gravitational acceleration G by the vehicle speed V, i.e., which exceeds min{(V/R), (G/V)}, the side-slip of the vehicle is nearly “0” in a usual traveling state of the vehicle. Therefore, the abnormality of the yaw rate sensor, including the state in which the neutral point is normal, but the sensitivity is abnormal, can be detected with good accuracy, irrespective of the situation of the road surface traveled.
To achieve the first object, there is also provided a system for detecting an abnormality of a yaw rate sensor, comprising a vehicle speed detecting means for detecting a vehicle speed of a vehicle, a steering angle sensor for detecting a steering angle of a steering wheel, a multiplying means for multiplying the steering angle detected by the steering angle sensor by the vehicle speed detected by the vehicle speed detecting means and by a given constant, a dividing means for dividing a gravitational acceleration by the vehicle speed detected by the vehicle speed detecting means, a low-select means for selecting a lower one of outputs from the multiplying means and the dividing means, and an abnormality determining means for determining that a yaw rate sensor is abnormal when a yaw rate detected by the yaw rate sensor exceeds a value selected by the low-select means.
When the steering angle detected by the steering angle sensor is represented by &dgr;, and a constant is represented by k, the radius of turning of the vehicle is capable of being presumed with {1/(&dgr;·k)}, until the centripetal acceleration becomes a limit value. If (V/R) in
FIG. 3
is replaced by (&dgr;·V·k), the range of yaw rate &ggr; capable of being actually produced can be determined more precisely than an obliquely-lined range shown in FIG.
3
. Therefore, when the yaw rate &ggr; is in a range which exceeds a lower one of a value (&dgr;·V·k) obtained by multiplying the steering angle &dgr; by the vehicle speed V and the given constant k and a value (G/V) obtained by dividing the gravitational acceleration G by the vehicle speed, i.e., which exceeds min{(&dgr;·V·k), (G/V)}, the side-slip of the vehicle is nearly “0” in a normal traveling state. Therefore, the abnormality of the yaw rate sensor, including the state in which the neutral point is normal, but the sensitivity is abnormal, can be detected with a good accuracy, irrespective of the situation of a road surface traveled.
To achieve the first object, there is also provided a system for detecting an abnormality of a yaw rate sensor, comprising a vehicle speed detecting means for detecting a vehicle speed of a vehicle, a lateral acceleration sensor for detecting a lateral acceleration of the vehicle, a dividing means for dividing the vehicle speed detected by the vehicle speed detecting means by a minimum turning radius of the vehicle, a dividing means for dividing the lateral acceleration detected by the lateral acceleration sensor by the vehicle speed detected by the vehicle speed detecting means, a low-select means for selecting a lower one of outputs from both of the dividing means, and an abnormality determining means for determining that a yaw rate sensor is abnormal when a yaw rate detected by the yaw rate sensor exceeds the value selected by the low-select means.
When the lateral acceleration detected by the lateral acceleration sensor is represented by &agr;, the range of yaw rate capable of being actually produced can be determined more precisely than the obliquely lined range shown in
FIG. 3
by replacing (G/V) in
FIG. 3
by (&agr;/V). Therefore, when the yaw rate &ggr; is in a range which exceeds lower one of a value (V/R) obtained by dividing the vehicle speed V by the minimum radius of turning of the vehicle and a value (&agr;/V) obtained by dividing the lateral acceleration &agr; by the vehicle speed V, i.e., which exceeds min{(V/R), (&agr;/V)}, the side-slip of the vehicle is nearly “0” in a usual traveling state. Thus, the abnormality of the yaw rate sensor, including the state in which the neutral point is normal, but the sensitivity is abnormal, can be detected with a good accuracy, irrespective of the situation of a road surface traveled.
To achieve the first ob
Armstrong Westerman Hattori McLeland & Naughton LLP
Honda Giken Kogyo Kabushiki Kaisha
Raevis Robert
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