Apparatus for estimating current heading using magnetic and angular velocity sensors

• US 5,319,561 A
• Filed: 01/10/1992
• Issued: 06/07/1994
• Est. Priority Date: 01/21/1991
• Status: Expired due to Fees

• Current Assignee: Sumitomo Electric Industries Limited (Sumitomo Corporation)
• Original Assignee: Sumitomo Electric Industries Limited (Sumitomo Corporation)
• Inventors: Matsuzaki, Shin-ichi
• Primary Examiner(s): Black, Thomas G.
• Assistant Examiner(s): ZANELLI, MICHAEL J
• Application Number:
  US07/818,901
• Time in Patent Office: 879 Days
• Field of Search: 364/454, 364/571.02, 364/457, 364/449, 324/207.12, 33/319, 33/324, 33/326, 340/988, 340/995
• US Class Current: 701/221
• CPC Class Codes: G01C 17/38 Testing, calibrating, or compensating of compasses
• CPC Class Codes: G01C 19/42 for indicating rate of turn; for integrating rate of turn
• CPC Class Codes: G01C 21/005 with correlation of navigation data from several sources, e.g. map or contour matching G01C21/30 takes precedence
• CPC Class Codes: G01C 21/28 with correlation of data from several navigational instruments

Abstract

A heading detecting apparatus which calculates a Kalman filter gain by individually analyzing and evaluating error factors contained in the output data of turning angular velocity and magnetic sensors, determines the rate of use of the turning angular velocity and magnetic sensors on the basis of the Kalman filter gain and estimates a current heading of a moving body.

Claims

1. In a navigation system comprising:

a magnetic sensor for sensing a heading of a moving body;

a turning angular velocity sensor for sensing a heading of said moving body;

a locator connected to said turning angular velocity sensor and said magnetic sensor for determining a current estimated heading of said moving body from said magnetic sensor output and from said turning angular velocity sensor output,

a navigation controller responsive to the current heading determined by said locator to determine the current location of said moving body with respect to a map, and

means to display the location of said moving body on said map, the improvement wherein said locator comprises;

first means connected to said turning angular velocity sensor for measuring an error of a bias value that is contained in an output of said turning angular velocity sensor as said moving body is in its stopped state;

second means connected to said first means for calculating a current error that is contained in the output of said turning angular velocity sensor, in accordance with said error of said bias value measured by said first means that is multiplied by an elapsed time after said moving body moves, a change rate of time of said error of said bias value multiplied by said elapsed time, and the output of said turning angular velocity sensor multiplied by an error of a scale factor of said turning angular velocity sensor;

third means connected to said magnetic sensor for calculating a degree of magnetization of said moving body and an error of said degree of magnetization from heading data outputted from said magnetic sensor under a predetermined condition as said moving body is in its traveling state;

fourth means connected to said third means for calculating a change in said degree of magnetization of said moving body and an error of said change from heading data outputted from said magnetic sensor under said predetermined condition as said moving body is in its traveling state;

fifth means connected to said fourth means for calculating a current degree of magnetization of said moving body and an error of said current degree of magnetization in accordance with said degree of magnetization of said moving body and said error of said degree of magnetization that were calculated by said third means and with said change in said degree of magnetization of said moving body and said error of said change that were calculated by said fourth means;

sixth means connected to said turning angular sensor and to said magnetic sensor for calculating a change in a difference between the heading data of said magnetic sensor and heading data obtained from the output of said turning angular sensor;

seventh means connected to said fifth means and to said sixth means for calculating an error that is contained in heading data output of said magnetic sensor, in accordance with said change in said difference between the heading data of said magnetic sensor and the heading data obtained from the output of said turning angular sensor that was calculated by said sixth means and in accordance with said error of the current degree of magnetization of the moving body calculated by said fifth means;

eighth means connected to said second means and to said seventh means for calculating a Kalman filter gain by calculating a reliability in the output data of each sensor from said error in the output of said turning angular velocity sensor calculated by said second means and from said error of said heading data output of said magnetic sensor calculated by said seventh means; and

ninth means connected to said eighth means for calculating a current estimated heading of said moving body by processing the heading data calculated from the magnetic sensor output and the heading data calculated from the turning angular velocity sensor output with weight processing based upon said Kalman filter gain.

2. A heading detecting apparatus as set forth in claim 1, wherein said moving body is a vehicle.