Offset detection of acceleration sensor and navigation system

• US 20070067096A1
• Filed: 08/28/2006
• Published: 03/22/2007
• Est. Priority Date: 09/06/2005
• Status: Active Grant

• Current Assignee: Sony Corporation (Sony Group Corp.)
• Original Assignee: Sony Corporation (Sony Group Corp.)
• Inventors: Takaoka, Tomohisa, Ohkubo, Masashi
• Granted Patent: US 7,747,383 B2
• Time in Patent Office: Days
• US Class Current: 701/207
• CPC Class Codes: G01C 21/28 with correlation of data from several navigational instruments
• CPC Class Codes: G01P 7/00 Measuring speed by integrating acceleration measuring travelled distance by double integration of acceleration G01C21/16

Abstract

To accurately detect a zero gravity offset in an acceleration sensor. As an embodiment of the present invention, in the case where position information can be obtained from a GPS processing section, a velocity detecting unit performs an operation according to Expression (15), using real detected acceleration αGr that was actually obtained from the acceleration sensor, vehicle acceleration αP based on the position information, distance Dm, an amount of height change Dh based on pressure PR, and gravity acceleration g. Therefore, offset acceleration αo can be accurately calculated, and an acceleration detection signal can be converted into detected acceleration αG with high accuracy, based on a zero gravity offset value Vzgo by that the above offset acceleration αo was converted.

Claims

1. An offset detecting system of an acceleration sensor, comprising:

an acceleration sensor for obtaining real detected acceleration corresponding to the result of that offset variance was added to acceleration in a forward direction in a predetermined mobile body;

acceleration to be detected calculating means for calculating acceleration to be detected that should be primarily correctly detected by said acceleration sensor; and

offset calculating means for calculating said offset variance that said real detected acceleration varied from the acceleration to be detected by the characteristic of said acceleration sensor, based on the difference between said real detected acceleration and the acceleration to be detected.

2. The offset detecting system of an acceleration sensor according to claim 1, wherein;

said acceleration to be detected calculating means calculates said acceleration to be detected, by calculating mobile body acceleration showing the acceleration of said mobile body itself and the component of said forward direction being gravity acceleration operating on said mobile body respectively and adding them.

3. The offset detecting system of an acceleration sensor according to claim 2, including:

a pressure sensor for detecting pressure; and

moving distance calculating means for calculating the moving distance of said mobile body in a predetermined measurement time;

wherein said acceleration to be detected calculating means calculates the amount of height change of said mobile body in said measurement time, based on the pressure detected by said pressure sensor, and calculates the component of said forward direction being said gravity acceleration using the ratio of said moving distance to the above amount of height change, and a gravity acceleration constant.

4. The offset detecting system of an acceleration sensor according to claim 3, wherein;

when said amount of height change is not within a predetermined range of height change, said acceleration to be detected calculating means corrects said amount of height change to be within the above range of amount of height change.

5. The offset detecting system of an acceleration sensor according to claim 3, wherein;

said acceleration to be detected calculating means determines whether or not said amount of height change is within said range of height change, based on a maximum slope angle being the maximum value of a slope angle that is obtained from said amount of height change.

6. The offset detecting system of an acceleration sensor according to claim 3, wherein;

said acceleration to be detected calculating means determines whether or not said amount of height change is within said range of height change, based on a maximum slope change rate being the maximum value of a slope change rate per unit time of a slope angle that is obtained from said amount of height change.

7. The offset detecting system of an acceleration sensor according to claim 2, wherein;

said moving distance calculating means calculates said moving distance using position information or velocity information obtained by predetermined satellite positioning signal receiving and positioning means.

8. An offset detecting method of an acceleration sensor, comprising the steps of:

obtaining real detected acceleration corresponding to the result of that offset variance was added to acceleration in a forward direction in a predetermined mobile body, by an acceleration sensor;

calculating acceleration to be detected that should be primarily correctly detected by said acceleration sensor; and

calculating said offset variance that said real detected acceleration varied from the acceleration to be detected by the characteristic of said acceleration sensor, based on the difference between said real detected acceleration and the acceleration to be detected.

9. An offset detecting program of an acceleration sensor for making an offset detecting system of an acceleration sensor execute the steps of:

obtaining real detected acceleration corresponding to the result of that offset variance was added to acceleration in a forward direction in a predetermined mobile body, by an acceleration sensor;

calculating acceleration to be detected that should be primarily correctly detected by said acceleration sensor; and

calculating said offset variance that said real detected acceleration varied from the acceleration to be detected by the characteristic of said acceleration sensor, based on the difference between said real detected acceleration and the acceleration to be detected.

10. A navigation system comprising:

present position calculating means for receiving a positioning signal from a predetermined satellite positioning system, and calculating the present position of a predetermined mobile body;

an acceleration sensor for obtaining real detected acceleration corresponding to the result of that offset variance was added to acceleration in a forward direction in a predetermined mobile body;

acceleration to be detected calculating means for calculating acceleration to be detected that should be primarily correctly detected by said acceleration sensor;

offset calculating means for calculating said offset variance that said real detected acceleration varied from the acceleration to be detected by the characteristic of said acceleration sensor, based on the difference between said real detected acceleration and the acceleration to be detected; and

information display means for calculating said acceleration using said offset variance that was calculated by said offset calculating means, and displaying information on the position of said mobile body based on the velocity of said mobile body calculated using the above acceleration.

11. An offset detecting system of an acceleration sensor, comprising:

an acceleration sensor for obtaining real detected acceleration corresponding to the result of that offset variance was added to acceleration in a forward direction in a predetermined mobile body;

an acceleration to be detected calculating section calculating acceleration to be primarily correctly detected by said acceleration sensor; and

an offset calculating section calculating said offset variance that said real detected acceleration varied from the acceleration to be detected by the characteristic of said acceleration sensor, based on the difference between said real detected acceleration and the acceleration to be detected.

12. The offset detecting system of an acceleration sensor according to claim 11, wherein;

said acceleration to be detected calculating section calculates said acceleration to be detected, by calculating mobile body acceleration showing the acceleration of said mobile body itself and the component of said forward direction being gravity acceleration operating on said mobile body respectively and adding them.

13. The offset detecting system of an acceleration sensor according to claim 12, including:

a pressure sensor for detecting pressure; and

a moving distance calculating section calculating the moving distance of said mobile body in a predetermined measurement time;

wherein said acceleration to be detected calculating section calculates the amount of height change of said mobile body in said measurement time, based on the pressure detected by said pressure sensor, and calculates the component of said forward direction being said gravity acceleration using the ratio of said moving distance to the above amount of height change, and a gravity acceleration constant.

14. The offset detecting system of an acceleration sensor according to claim 13, wherein;

when said amount of height change is not within a predetermined range of height change, said acceleration to be detected calculating section corrects said amount of height change to be within the above range of amount of height change.

15. The offset detecting system of an acceleration sensor according to claim 13, wherein;

said acceleration to be detected calculating section determines whether or not said amount of height change is within said range of height change, based on a maximum slope angle being the maximum value of a slope angle that is obtained from said amount of height change.

16. The offset detecting system of an acceleration sensor according to claim 13, wherein;

said acceleration to be detected calculating section determines whether or not said amount of height change is within said range of height change, based on a maximum slope change rate being the maximum value of a slope change rate per unit time of a slope angle that is obtained from said amount of height change.

17. The offset detecting system of an acceleration sensor according to claim 12, wherein;

said moving distance calculating section calculates said moving distance using position information or velocity information obtained by a predetermined satellite positioning signal receiving and positioning section.

18. An offset detecting system of an acceleration sensor, comprising:

an acceleration sensor for obtaining real detected acceleration corresponding to the result of that offset variance was added to acceleration in a forward direction in a predetermined mobile body;

an acceleration to be detected calculating section calculating acceleration to be detected that should be primarily correctly detected by said acceleration sensor; and

an offset calculating section calculating said offset variance that said real detected acceleration varied from the acceleration to be detected by the characteristic of said acceleration sensor, based on the difference between said real detected acceleration and the acceleration to be detected.