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EP0485132A2
Expired / Lapsed
EP
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Direction sensor having an earth magnetism sensor and a rate gyro sensor and navigation system having this direction sensor
Assignee: Denso Ten Ltd
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Filing: 1991-11-04
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Granted: —
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Expires: 2011-11-04
Abstract
Abstract The direction sensor has an earth magnetism sensor (1) and a rate gyro sensor (2) that calculates a compensated direction by weighted mean process of outputs from the earth magnetism sensor and the rate gyro sensor. The compensated direction has a high detection accuracy similar to the rate gyro sensor in a short time, but does not have an error accumulation of the rate gyro sensor in a long time because the rate gyro sensor is subsantially calibrated with the accurate direction obtained by averaging outputs of the earth magnetism sensor. The navigation system has distribution information of the magnetic disturbances to earth magnetism on a map (5) and it reduces the weighted mean ratio to the earth magnetism sensor (1) when the magnetic disturbance at locating position is large. The accuracy of the compensated direction is further improved by excluding inaccurate outputs of the earth magnetism sensor (1).
Inventors
- 👤 Atsushi Ichimura
- 👤 Yasuhiro Nakatani
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-03 17:35
CPC Classifications
G; G01; G01C; G01C21/00; G01C21/26; G01C21/28; B; B60; B60T; B60T2250/00; B60T2250/06; B60T2250/062
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
134 words
A driving direction sensor of a vehicle for outputting a compensated direction, comprising: an earth magnetism sensor (1) for detecting a forward angle relative to magnetic north of earth and outputting a first driving direction calculated from said detected forward angle, a rate gyro sensor (2) for calculating a rotated angle from detected rotating speed and for outputting a second driving direction obtained by adding said rotated angle to a reference direction, and a direction compensating means (3) for calculating a compensated direction from said first driving direction and said second driving direction, characterized in that said direction compensating means (3) calculates said compensated direction by a weighted mean process of said first driving direction and said second driving direction, and sets said compensated direction as said reference direction of said rate gyro sensor.
Claim 2
Dependent Claim
32 words
A driving direction sensor of a vehicle as set forth in claim 1, wherein a weighted mean ratio of said weighted mean process changes according to a driving time of said vehicle.
Claim 3
Dependent Claim
44 words
A driving direction sensor of a vehicle as set forth in claim 1, wherein a weighted mean ratio of said weighted mean process changes according to a temperature of said rate gyro sensor (2) or an environment temperature of said rate gyro sensor (2).
Claim 4
Dependent Claim
72 words
A navigation system comprising: a driving direction sensor (10) for detecting a driving direction, a driving distance sensor (4) for detecting a driving distance, a road map storing means (5) for storing information relating to a road map, and a locating position calculating means (6) for calculating a locating position on said road map, characterized in that said driving direction sensor (10) is a direction sensor as set forth in claim 1.
Claim 5
Dependent Claim
79 words
A navigation system as set forth in claim 4, wherein said navigation system comprising: a disturbance data storing means (7) for storing distribution information of magnetic disturbance to earth magnetism in a form corresponding to said road map, and a ratio changing means (8) for detecting an intensity of magnetic disturbance at said locating position from said disturbance data storing means (7) and changing a weighted mean ratio of said weighted mean process according to said magnetic disturbance intensity.
Claim 6
Dependent Claim
86 words
A navigation system as set forth in claim 5, wherein said disturbance data storing means (7) comprises locating positions of specific facilities and respective influence ranges of said specific facilities in which each disturbance of said specific facilities to earth magnetism is more than a predetermined level,and said ratio changing means (8) further comprises a distance calculating means for calculating distances between said specific facilities and said locating position and changes said weighted mean ratio whether or not said locating position is within said influence range.
Claim 7
Dependent Claim
36 words
A navigation system as set forth in claim 6, wherein said ratio changing means (8) changes said weighted mean ratio of said first driving direction to 0 when said locating position is within said disturbance range.
Claim 8
Dependent Claim
24 words
A navigation system as set forth in claim 6, wherein said ratio changing means (8) changes said weighted mean ratio between 0 and 1.
Claim 9
Dependent Claim
190 words
A navigation system of a vehicle for offering a locating position on a map, comprising: an earth magnetism sensor (1) for detecting a forward angle relative to magnetic north of earth and outputting a first driving direction calculated from said detected forward angle, a rate gyro sensor (2) for calculating a rotated angle from detected rotating speed and for outputting a second driving direction obtained by adding said rotated angle to a reference direction, a direction compensating means (3) for calculating a compensated direction from said first driving direction and said second driving direction, a driving distance sensor (4) for detecting a driving distance, a road map storing means (5) for storing information relating to a road map, and a locating position calculating means (6) for calculating a locating position on said road map, characterized in that said navigation system comprising: a disturbance data storing means (7) for storing distribution information of magnetic disturbance to earth magnetism in a form corresponding to said road map, and a changing means (8) for detecting an intensity of magnetic disturbance at said locating position and changing a calculating process of said compensated direction.
References Cited (Backward Citations)
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