Vehicle driving azimuth detecting apparatus for correcting a disturbed geomagnetic azimuth
First Claim
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1. An apparatus for detecting a present driving azimuth of a vehicle, said apparatus comprising:
- a geomagnetic sensor which senses a plurality of geomagnetic azimuth values of said vehicle to produce a first geomagnetic variation amount in said plurality of geomagnetic azimuth values;
a gyroscopic sensor which senses a plurality of gyroscopic azimuth values of said vehicle to produce a second gyroscopic variation amount in said plurality of gyroscopic azimuth values;
a processor which determines a geomagnetic condition surrounding said vehicle by calculating a difference between said first geomagnetic variation amount and said second gyroscopic variation amount and outputs a geomagnetic condition signal representative of geomagnetic conditions surrounding said vehicle, said processor also determining said present driving azimuth of said vehicle based on said difference between said first geomagnetic variation amount and said second gyroscopic variation amount and on said geomagnetic condition signal such that a plurality of differences of said first geomagnetic variation amount and said second gyroscopic variation amount are acquired and averaged to obtain an averaged difference according to ##EQU1## where M is a number of azimuth detections (M≧
2), Δ
θ
G is said second gyroscopic variation amount, and, Δ
θ
M is said first geomagnetic variation amount and said present driving azimuth θ
3 is generated according to
space="preserve" listing-type="equation">θ
.sub. ={α
/(β
.sup.n +1)}·
(θ
.sub.M -θ
.sub.2)+θ
.sub.2, where α
is a first constant (0≦
α
≦
1), n is a second constant, θ
M is said geomagnetic azimuth, and θ
2 corresponds to Δ
θ
G +θ
3 acquired in a previous azimuth detection.
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Abstract
In an apparatus for detecting a driving azimuth of a vehicle, a gyroscopic sensor signal and a geomagnetic sensor signal are acquired. When the vehicle is driven in a disturbed geomagnetic area such as a straight road, the acquired geomagnetic sensor signal does not correctly reflect the actual driving azimuth of the vehicle. Moreover, the gyroscopic sensor signal drifts over time. When the vehicle is in such a disturbed geomagnetic area, a variation amount in the acquired geomagnetic sensor signals is subtracted from another variation amount in the acquired gyroscopic sensor signals to obtain a driving azimuth similar to the actual driving azimuth.
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Citations
5 Claims
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1. An apparatus for detecting a present driving azimuth of a vehicle, said apparatus comprising:
-
a geomagnetic sensor which senses a plurality of geomagnetic azimuth values of said vehicle to produce a first geomagnetic variation amount in said plurality of geomagnetic azimuth values; a gyroscopic sensor which senses a plurality of gyroscopic azimuth values of said vehicle to produce a second gyroscopic variation amount in said plurality of gyroscopic azimuth values; a processor which determines a geomagnetic condition surrounding said vehicle by calculating a difference between said first geomagnetic variation amount and said second gyroscopic variation amount and outputs a geomagnetic condition signal representative of geomagnetic conditions surrounding said vehicle, said processor also determining said present driving azimuth of said vehicle based on said difference between said first geomagnetic variation amount and said second gyroscopic variation amount and on said geomagnetic condition signal such that a plurality of differences of said first geomagnetic variation amount and said second gyroscopic variation amount are acquired and averaged to obtain an averaged difference according to ##EQU1## where M is a number of azimuth detections (M≧
2), Δ
θ
G is said second gyroscopic variation amount, and, Δ
θ
M is said first geomagnetic variation amount and said present driving azimuth θ
3 is generated according to
space="preserve" listing-type="equation">θ
.sub. ={α
/(β
.sup.n +1)}·
(θ
.sub.M -θ
.sub.2)+θ
.sub.2,where α
is a first constant (0≦
α
≦
1), n is a second constant, θ
M is said geomagnetic azimuth, and θ
2 corresponds to Δ
θ
G +θ
3 acquired in a previous azimuth detection. - View Dependent Claims (2, 3, 4, 5)
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Specification
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Current AssigneeNissan Motor Co., Ltd.
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Original AssigneeNissan Motor Co., Ltd.
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InventorsNakayama, Okihiko, Tsuda, Hiroshi
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Primary Examiner(s)Lall, Parshotam S.
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Assistant Examiner(s)ZANELLI, MICHAEL J
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Application NumberUS07/316,836Time in Patent Office994 DaysField of Search364/559, 364/449, 364/450, 364/457, 364/571.05, 364/453, 364/571.01, 364/571.03, 364/575, 364/454, 73/1 E, 73/178 R, 340/995, 340/988, 33/356US Class Current701/220CPC Class CodesG01C 17/38 Testing, calibrating, or co...G01C 21/28 with correlation of data fr...
