Calibration apparatus of angular velocity sensor in self-contained navigational system

• US 5,115,238 A
• Filed: 04/02/1990
• Issued: 05/19/1992
• Est. Priority Date: 04/07/1989
• Status: Expired due to Term

• Current Assignee: Sumitomo Electric Industries Limited (Sumitomo Corporation)
• Original Assignee: Sumitomo Electric Industries Limited (Sumitomo Corporation)
• Inventors: Doi, Yoichi, Mito, Kunihiko, Shimizu, Osamu, Tenmoku, Kenji
• Primary Examiner(s): Ng, Jin F.
• Assistant Examiner(s): SWARTHOUT, BRENT
• Application Number:
  US07/502,551
• Time in Patent Office: 778 Days
• Field of Search: 340/988, 340/995, 340/990, 73/178 R, 364/443, 364/449, 364/444, 364/457, 364/460
• US Class Current: 340/988
• CPC Class Codes: G01C 17/38 Testing, calibrating, or compensating of compasses
• CPC Class Codes: G01C 21/30 Map- or contour-matching

Abstract

A calibration apparatus of an angular-velocity detection sensor for detecting a heading of a vehicle which is used in a self-contained navigational system, comprising an angular-velocity detection unit for calculating an angular velocity from an output signal of the angular-velocity detection sensor; an integration unit for calculating a current heading of the vehicle by integrating the angular velocity and by adding the integrated angular velocity to the previous heading of the vehicle; a location and heading detection unit which estimates a location of the vehicle from the current heading calculated by the integration unit, a heading obtained by a magnetic sensor and from a distance obtained by a distance sensor and which compares the estimated location with road network data obtained from a road map memory to obtain an estimated heading of the vehicle; and a heading correction unit for calculating a difference between the heading of the integration unit and the heading of the location and heading detection unit and integrating the difference over a predetermined distance to obtain an error per unit distance, for calculating the difference or the error per unit distance, as a correction value for correcting the current heading of the integration unit, and for feeding the correction value back to the intergration unit. The current heading of the integration unit is corrected by subtracting the correction value from the current heading of the integration unit.

Claims

1. A calibration apparatus of an angular-velocity detection sensor for detecting a heading of a vehicle which is used in a self-contained navigational system, comprising:

angular-velocity detection means for calculating an angular velocity from an output signal of said angular-velocity detection sensor;

integration means for calculating a current heading of the vehicle by integrating said angular velocity and by adding the integrated angular velocity to the previous heading of the vehicle;

location and heading detection means which estimates a location of the vehicle from said current heading calculated by said integration means, a heading obtained by a magnetic sensor and from a distance obtained by a distance sensor and which compares the estimated location with road network data obtained from a road map memory to obtain an estimated heading of the vehicle; and

heading correction means for calculating a difference between said current heading of said integration means and said estimated heading of said location and heading detection means and integrating said difference over a predetermined distance to obtain an error per unit distance, for calculating said difference or said error per unit distance, as a correction value for correcting said current heading of said integration means, and for feeding said correction value back to said integration means;

said current heading of said integration means being corrected by subtracting said correction value from said current heading of said integration means.

3. A calibration apparatus as set forth in claim 1, which further comprises initial-heading set means for setting, when said vehicle starts travelling on a road, an output of said magnetic sensor or a heading of the road as an initial heading of said vehicle.

2. A calibration apparatus of an angular-velocity detection sensor for detecting a heading of a vehicle which is used in a self-contained navigational system, comprising:

angular-velocity detection means for calculating an angular velocity from an output signal of said angular-velocity detection sensor;

integration means for calculating a current heading of the vehicle by integrating said angular velocity and by adding the integrated angular velocity to the previous heading of the vehicle;

location and heading detection means which estimates a locations of the vehicle from said current heading calculated by said integration means, a heading obtained by a magnetic sensor and from a distance obtained by a distance sensor and which compares the estimated location with road network data obtained from a road map memory to obtain an estimated heading of the vehicle; and

heading correction means which calculates a first change between heading outputs obtained from said integration means before and after a turning of the vehicle and a second change between heading outputs obtained from said location and heading detection means before and after the turning of the vehicle, and which calculates a correction value for correcting said angular velocity of said angular-velocity detection means, by performing a predetermined arithmetic operation on the basis of said first and second changes, and which feeds said correction value back to said angular-velocity detection means in which said angular velocity is corrected with said correction value.

4. A calibration apparatus as set forth in claim 2, which further comprises initial-heading set means for setting, when said vehicle start travelling on a road, an output of said magnetic sensor or a heading of the road as an initial heading of said vehicle.