Position calculating method and position calculating device

• US 8,134,496 B2
• Filed: 11/05/2009
• Issued: 03/13/2012
• Est. Priority Date: 11/11/2008
• Status: Active Grant

• Current Assignee: Seiko Epson Corporation (Seiko Group)
• Original Assignee: Seiko Epson Corporation (Seiko Group)
• Inventors: Mizuochi, Shunichi, Imafuku, Shigeru, Anand, Kumar, Onda, Kenji
• Primary Examiner(s): LIU, HARRY K
• Application Number:
  US12/613,154
• Publication Number:
  US 20100117895A1
• Time in Patent Office: 859 Days
• Field of Search: 342/357.3, 342/357.32, 342/357.2
• US Class Current: 342/357.2
• CPC Class Codes: G01S 19/49 whereby the further system is an inertial position system, e.g. loosely-coupled

Abstract

A position calculating method includes: calculating a position of a mobile body based on a positioning signal from a positioning satellite; determining the moving condition of the mobile body based on a detection result of a sensor unit including at least one of an acceleration sensor, an angular speed sensor, and an azimuth sensor; changing an error parameter used for a predetermined Kalman filter process according to the determined moving condition; and correcting the calculated position by the Kalman filter process.

Claims

1. A position calculating method comprising:

calculating a position of a mobile body based on a positioning signal from a positioning satellite;

determining a moving condition of the mobile body based on a detection result of a sensor unit including at least one of an acceleration sensor, an angular speed sensor, and an azimuth sensor;

changing an error parameter used for a predetermined Kalman filter process according to the determined moving condition, the error parameter being parameters corresponding to diagonal components of an east position, north position, moving speed, and azimuth per time of a condition vector; and

correcting the calculated position by the Kalman filter process.

2. The position calculating method according to claim 1, wherein

the sensor unit includes at least an acceleration sensor;

determining the moving condition includes determining whether the mobile body is in a stopping condition or not;

the method further includes calculating a moving speed of the mobile body based on the positioning signal from the positioning satellite;

and

changing the error parameter includes changing the speed error parameter according to the determination whether the mobile body is in the stopping condition or not.

3. The position calculating method according to claim 1, wherein

the sensor unit includes at least an acceleration sensor;

determining the moving condition includes determining whether the mobile body is in a stopping condition or not;

the method further includes calculating the moving speed of the mobile body based on the positioning signal from the positioning satellite;

the error parameter includes a speed time-varying parameter indicating time-varying allowance of the calculated moving speed; and

changing the error parameter includes changing the speed time-varying parameter according to the determination whether the mobile body is in the stopping condition or not.

4. The position calculating method according to claim 1, wherein

the sensor unit includes at least an angular speed sensor and an azimuth sensor;

determining the moving condition includes determining whether the mobile body is in a rotating condition or not;

and

changing the error parameter includes changing the azimuth error parameter according to the determination whether the mobile body is in the rotating condition or not.

5. The position calculating method according to claim 1, wherein

the sensor unit includes at least an angular speed sensor and an azimuth sensor;

determining the moving condition includes determining whether the mobile body is in a rotating condition or not;

the error parameter includes a direction time-varying parameter indicating time-varying allowance of the calculated moving direction of the mobile body; and

changing the error parameter includes changing the direction time-varying parameter according to the determination whether the mobile body is in the rotating condition or not.

6. The position calculating method according to claim 1, wherein

the sensor unit includes at least an acceleration sensor and an azimuth sensor;

determining the moving condition includes determining whether the mobile body is in a high acceleration condition or not;

the method further includes calculating the moving speed of the mobile body based on the positioning signal from the positioning satellite;

and

changing the error parameter includes changing the speed error parameter according to the determination whether the mobile body is in the high acceleration condition or not.

7. The position calculating method according to claim 1, wherein

the sensor unit includes at least an acceleration sensor and an azimuth sensor;

determining the moving condition includes determining whether the mobile body is in a high acceleration condition or not;

the method further includes calculating the moving speed of the mobile body based on the positioning signal from the positioning satellite;

the error parameter includes a speed time-varying parameter indicating time-varying allowance of the calculated moving speed; and

changing the error parameter includes changing the speed time-varying parameter according to the determination whether the mobile body is in the high acceleration condition or not.

8. A position calculating device comprising:

a calculating unit which calculates a position of a mobile body based on a positioning signal from a positioning satellite;

a determining unit which determines a moving condition of the mobile body based on a detection result of a sensor unit including at least one of an acceleration sensor, an angular speed sensor, and an azimuth sensor;

a parameter changing unit which changes an error parameter used for a predetermined Kalman filter process according to the moving condition determined by the determining unit, the error parameter being parameters corresponding to diagonal components of an east position, north position, moving speed, and azimuth per time of a condition vector; and

a Kalman filter processing unit which corrects the position calculated by the calculating unit by the Kalman filter process.