Data processing: measuring – calibrating – or testing – Measurement system – Orientation or position
Reexamination Certificate
1999-01-06
2001-11-20
Hoff, Marc S. (Department: 2857)
Data processing: measuring, calibrating, or testing
Measurement system
Orientation or position
C362S459000
Reexamination Certificate
active
06321176
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a device for calculating a pitch angle for a vehicle.
2. Description of the Related Art
In general, the pitch angle &thgr; for a vehicle is calculated by the following expression:
θ
=
tan
-
1
hf
-
hr
w
(
1
)
where
hf is a vehicle height at a front wheel,
hr is a vehicle height at a rear wheel, and
w is a wheel base length.
It is noted that in the above expression (1), changes from respective heights under the vehicle's initial condition, which will be referred as “initial values” hereinafter, are entered into the vehicle heights hf, hr, respectively. Accordingly, the pitch angle &thgr; of the vehicle under the initial condition is equal to an angle of zero (0) degree.
Now, in the vehicle height, there are a long-sustained variation derived from a number of passengers, a position of passengers, a weight of loads and a position of loads, and an instantaneous variation due to an acceleration (or deceleration) of the vehicle, the vehicle's getting over the irregularities and obstacles on the road and so on. The former variation in vehicle height produces a long-term pitch angle, while the latter variation in vehicle height produces an instantaneous (short-term) pitch angle. Therefore, if the pitch angle is calculated on the basis of a detected vehicle height including the latter instantaneous variation in vehicle height, then a pitch angle obtained as a calculation result will change furiously, which is undesirable for using it in an automatic control of leveling a headlamp of the vehicle, namely, “auto-levelizer”.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a pitch angle calculating device which is capable of calculating a right and reliable pitch angle suitable for the use in such a control while restricting an occurrence of unnecessary pitch angles due to the vehicle's getting over the irregularities and obstacles etc. on the road.
In the first aspect of the invention, the above-mentioned object of the present invention can be accomplished by a pitch angle calculating device for a vehicle, comprising:
height detecting units arranged both in a front position (Pf) and in the rear position (Pr) of the vehicle, for detecting a vehicle height (hf) of the front position and a vehicle height (hr) of the rear position (Pr); and
a calculating section for calculating a pitch angle of the vehicle by the vehicle heights (hf, hr) and a distance between the front position (Pf) and the rear position (Pr);
wherein, on condition that the pitch angle is divided into a plurality of pitch angle ranges, the calculating section integrates periods residing in each pitch angle range and subsequently determines the pitch angle of the vehicle on a basis of the integrated periods referred as “residence time”.
In the second aspect of the invention, the above-mentioned object of the present invention can be also accomplished by a pitch angle calculating device for a vehicle, comprising:
a height detecting unit arranged in either one of a front position (Pf) and the rear position (Pr) of the vehicle, for detecting either a vehicle height (hf) of the front position or a vehicle height (hr) of the rear position (Pr); and
a calculating section for calculating a pitch angle of the vehicle by the vehicle heights (hf, hr) and a distance between the front position (Pf) and the rear position (Pr);
wherein, on conditions that the other of the vehicle heights (hf or hr) is established by a fixed value and that the pitch angle is divided into a plurality of pitch angle ranges, the calculating section integrates periods residing in each pitch angle range and subsequently determines the pitch angle of the vehicle on a basis of the residence time.
The above and other features and advantages of this invention will become apparent, and the invention itself will best be understood, from a study of the following description and appended claims, with reference to the attached drawings showing, some preferred embodiments of the invention.
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Foley & Lardner
Hoff Marc S.
Nissan Motor Co,. Ltd.
Raymond Edward
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