MOVING STATE DETECTING DEVICE

• US 20120041702A1
• Filed: 04/19/2010
• Published: 02/16/2012
• Est. Priority Date: 05/19/2009
• Status: Active Grant

• Current Assignee: Furuno Electric Co, Ltd
• Original Assignee: Furuno Electric Co, Ltd
• Inventors: Toda, Hiroyuki, Yoshitake, Ken
• Granted Patent: US 10,012,672 B2
• Time in Patent Office: Days
• US Class Current: 702/94
• CPC Class Codes: G01C 21/185 for gravity
• CPC Class Codes: G01P 21/00 Testing or calibrating of apparatus or devices covered by the preceding groups

Abstract

To accurately calculate an attached angle of an accelerometer and accurately correct an acceleration that is obtained from the accelerometer: a frequency analyzing module of an acceleration corrector divides a sensor coordinate system acceleration into a bias frequency component, a gravity frequency component, a movement acceleration frequency component, and a noise frequency component, through a wavelet transform. The frequency analyzing module outputs a sum component of the gravity frequency component and the movement acceleration frequency component to an attached angle estimating module and a correcting operation module. The attached angle estimating module estimation-calculates the attached angle of an accelerometer and outputs it to the correcting operation module. The correcting operation module corrects the acceleration, which is including of the sum component of the gravity frequency component and the movement acceleration frequency component, based on the estimation-calculated attached angle to calculate a movable body coordinate system acceleration.

Claims

1. A moving state detecting device, comprising:

an accelerometer installed in a movable body; and

an acceleration correcting module for dividing, for every frequency band, an acceleration that is obtained from the accelerometer, estimating an attached angle of the accelerometer based on a gravity frequency component and a movement acceleration frequency component that are formed by predetermined frequency band components, respectively, and correcting the acceleration based on the attached angle.

2. The moving state detecting device of claim 1, wherein the acceleration correcting module divides, for every frequency band, the acceleration obtained from the accelerometer into a bias frequency component, the gravity frequency component, the movement acceleration frequency component, and a noise frequency component, estimates the attached angle of the accelerometer based on the gravity frequency component and the movement acceleration frequency component, and corrects the acceleration based on the attached angle.

3. The moving state detecting device of claim 1 or 2, wherein the acceleration correcting module frequency-divides the acceleration through a wavelet transform.

4. The moving state detecting device of claim 1, wherein the accelerometer detects acceleration components with a front-and-rear direction acceleration component, a left-and-right direction acceleration component, and an up-and-down direction acceleration component, all of which are perpendicular to each other respectively, and

wherein the acceleration correcting module performs at least one of an estimation of an attached angle in an azimuth direction based on the front-and-rear direction acceleration component and the left-and-right direction acceleration component, an estimation of an attached angle in a pitch direction based on the front-and-rear direction acceleration component and the up-and-down direction acceleration component, and an estimation of an attached angle in a roll direction based on the front-and-rear direction acceleration component, the left-and-right direction acceleration component, the up-and-down direction acceleration component, and the pitch direction attached angle.

5. The moving state detecting device of claim 1, wherein the accelerometer detects acceleration components with a front-and-rear direction acceleration component, a left-and-right direction acceleration component, and an up-and-down direction acceleration component, all of which are perpendicular to each other respectively, and

wherein the acceleration correcting module estimates an attached angle in an azimuth direction based on the front-and-rear direction acceleration component and the left-and-right direction acceleration component, estimates an attached angle in a pitch direction based on the front-and-rear direction acceleration component and the up-and-down direction acceleration component, and estimates an attached angle in a roll direction based on the front-and-rear direction acceleration component, the left-and-right direction acceleration component, the up-and-down direction acceleration component, and the pitch direction attached angle.

6. The moving state detecting device of claim 4, wherein the acceleration correcting module estimates at least one of the azimuth direction attached angle and the pitch direction attached angle when the left-and-right direction acceleration component is below a predetermined threshold.

7. The moving state detecting device of claim 5, wherein when the left-and-right direction acceleration component is below a predetermined threshold, the acceleration correcting module estimates at least one of the azimuth direction attached angle and the pitch direction attached angle.

8. The moving state detecting device of claim 4, wherein when the left-and-right direction acceleration component is above the predetermined threshold, the acceleration correcting module estimates the roll direction attached angle.

9. The moving state detecting device of claim 1, wherein the acceleration correcting module sequentially stores the estimated attached angle as well as calculates the attached angle through time averaging processing, and, if the latest estimated attached angle is different from the previously estimated attached angle by a predetermined angle or above, reduces a weight of the previous attached angle in the time averaging processing.

10. The moving state detecting device of claim 1, comprising a speed/traveling-angle calculating module for calculating at least one of a speed of the movable body and a traveling pitch angle serving as an up-and-down direction inclination angle, based on the acceleration corrected by the acceleration correcting module.

11. The moving state detecting device of claim 10, wherein when the traveling pitch angle is calculated, the speed/traveling-angle calculating module calculates a divided value of the gravity frequency component by a gravity acceleration and corrects the calculated traveling pitch angle based on the divided value.

12. The moving state detecting device of claim 2, comprising a stop detecting module for detecting, when the noise frequency component is calculated, a stopping of the movable body by detecting a sum of the movement acceleration frequency component and the noise frequency component is below a predetermined threshold.

13. A navigation apparatus, comprising the moving state detecting device of claim 1, and wherein the navigation apparatus executes a position measurement of the apparatus itself and navigation processing based on information relating to a movement of the movable body calculated by the moving state detecting device.