Vehicle driving azimuth detecting apparatus for correcting a disturbed geomagnetic azimuth

Claim 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), Δθ G is said second gyroscopic variation amount, and, Δθ M is said first geomagnetic variation amount and said present driving azimuth θ 3 is generated according to 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 Δθ G +θ 3 acquired in a previous azimuth detection.

Claim 2

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), Δθ G is said second gyroscopic variation amount, and, Δθ M is said first geomagnetic variation amount and said present driving azimuth θ 3 is generated according to 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 Δθ G +θ 3 acquired in a previous azimuth detection.