The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Mar. 22, 1994
Filed:
Nov. 06, 1991
Atsushi Ichimura, Kobe, JP;
Yasuhiro Nakatani, Kobe, JP;
Fujitsu Ten Limited, Kobe, JP;
Abstract
The present invention involves a direction sensor and a navigation system containing the direction sensor. The direction sensor has an earth magnetism sensor and a rate gyro sensor that calculates a compensated direction by weighted means process of the 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 over a short time period, but does not have an error accumulation of the rate gyro sensor during a long time interval because the rate gyro sensor is substantially calibrated with the accurate direction obtained by the averaging outputs of the earth magnetism sensor. The navigation system has distribution information of the magnetic disturbances to the earth magnetism on a map and it reduces the weighted mean ration to the earth magnetism sensor when the magnetic disturbance at the locating position is large. The accuracy of the compensated direction is further improved by excluding inaccurate outputs of the earth magnetism sensor.