Offset detection of acceleration sensor and navigation system
First Claim
1. An offset detecting system of an acceleration sensor, comprising:
- an acceleration sensor to obtain real detected acceleration corresponding to a sum of an offset variance and acceleration in a forward direction of a predetermined mobile body;
calculating means for calculating a true acceleration that should be correctly detected by said acceleration sensor;
offset calculating means for calculating said offset variance representing an amount that said real detected acceleration varied from the true acceleration due to a characteristic of said acceleration sensor, based on a difference between said real detected acceleration and the true acceleration;
a pressure sensor to detect pressure; and
moving distance calculating means for calculating a moving distance of said mobile body in a predetermined measurement time,wherein said calculating means calculates an amount of height change of said mobile body in said measurement time, based on the pressure detected by said pressure sensor, and calculates a component in said forward direction of gravity acceleration using a ratio of said moving distance to the amount of height change, and a gravity acceleration constant.
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Accused Products
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.
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Citations
15 Claims
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1. An offset detecting system of an acceleration sensor, comprising:
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an acceleration sensor to obtain real detected acceleration corresponding to a sum of an offset variance and acceleration in a forward direction of a predetermined mobile body; calculating means for calculating a true acceleration that should be correctly detected by said acceleration sensor; offset calculating means for calculating said offset variance representing an amount that said real detected acceleration varied from the true acceleration due to a characteristic of said acceleration sensor, based on a difference between said real detected acceleration and the true acceleration; a pressure sensor to detect pressure; and moving distance calculating means for calculating a moving distance of said mobile body in a predetermined measurement time, wherein said calculating means calculates an amount of height change of said mobile body in said measurement time, based on the pressure detected by said pressure sensor, and calculates a component in said forward direction of gravity acceleration using a ratio of said moving distance to the amount of height change, and a gravity acceleration constant. - View Dependent Claims (2, 3, 4, 5, 6)
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7. An offset detecting method of an acceleration sensor, comprising:
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obtaining, by an acceleration sensor, real detected acceleration corresponding to a sum of an offset variance and acceleration in a forward direction of a predetermined mobile body; calculating a true acceleration that should be correctly detected by said acceleration sensor; calculating said offset variance representing an amount that said real detected acceleration varied from the true acceleration due to a characteristic of said acceleration sensor, based on a difference between said real detected acceleration and the true acceleration; and calculating a moving distance of said mobile body in a predetermined measurement time, wherein said step of calculating the true acceleration calculates an amount of height change of said mobile body in said measurement time, based on a pressure detected by a pressure sensor, and calculates a component in said forward direction of gravity acceleration using a ratio of said moving distance to the amount of height change, and a gravity acceleration constant.
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8. A computer readable medium storing an offset detecting program that, when executed, causes an offset detecting system of an acceleration sensor to execute the steps of:
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obtaining, by an acceleration sensor, real detected acceleration corresponding to a sum of an offset variance an acceleration in a forward direction of a predetermined mobile body; calculating a true acceleration that should be correctly detected by said acceleration sensor; calculating said offset variance representing an amount that said real detected acceleration varied from the true acceleration due to a characteristic of said acceleration sensor, based on a difference between said real detected acceleration and the true acceleration; and calculating a moving distance of said mobile body in a predetermined measurement time, wherein said step of calculating the true acceleration calculates an amount of height change of said mobile body in said measurement time, based on a pressure detected by a pressure sensor, and calculates a component in said forward direction of gravity acceleration using a ratio of said moving distance to the amount of height change, and a gravity acceleration constant.
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9. A navigation systems comprising:
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present position calculating means for receiving a positioning signal from a predetermined satellite positioning system, and for calculating a present position of a predetermined mobile body; an acceleration sensor to obtain real detected acceleration corresponding to a sum of an offset variance and acceleration in a forward direction of a predetermined mobile body; calculating means for calculating a true acceleration that should be correctly detected by said acceleration sensor; offset calculating means for calculating said offset variance representing an amount that said real detected acceleration varied from the true acceleration due to a characteristic of said acceleration sensor, based on a difference between said real detected acceleration and the acceleration; information display means for calculating said true acceleration using said offset variance that was calculated by said offset calculating means, and displaying information on a position of said mobile body based on a velocity of said mobile body calculated using the true acceleration; a pressure sensor to detect pressure; and moving distance calculating means for calculating a moving distance of said mobile body in a predetermined measurement time, wherein said calculating means calculates an amount of height change of said mobile body in said measurement time, based on the pressure detected by said pressure sensor, and calculates a component in said forward direction of gravity acceleration using a ratio of said moving distance to the amount of height change, and a gravity acceleration constant.
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10. An offset detecting system of an acceleration sensor, comprising:
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an acceleration sensor to obtain real detected acceleration corresponding to a sum of an offset variance and acceleration in a forward direction of a predetermined mobile body; a calculating section configured to calculate a true acceleration that should be correctly detected by said acceleration sensor; an offset calculating section configured to calculate said offset variance representing an amount that said real detected acceleration varied from the true acceleration due to a characteristic of said acceleration sensor, based on a difference between said real detected acceleration and the true acceleration; a pressure sensor to detect pressure; and a moving distance calculating section configured to calculate a moving distance of said mobile body in a predetermined measurement time, wherein said calculating section calculates an amount of height change of said mobile body in said measurement time, based on the pressure detected by said pressure sensor, and calculates a component in said forward direction of gravity acceleration using a ratio of said moving distance to the amount of height change, and a gravity acceleration constant. - View Dependent Claims (11, 12, 13, 14, 15)
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Specification