METHOD AND SYSTEM FOR AUTOMATICALLY CALIBRATING A THREE-AXIS ACCELEROMETER DEVICE
First Claim
1. A method for automatically aligning three accelerometer axes corresponding to an accelerometer device coordinate frame with three vehicle axes corresponding to a coordinate frame of a vehicle, comprising:
- determining second and third rotation angles;
retrieving a course signal value from a positioning circuit associated with the accelerometer device; and
determining a first rotation angle when the course signal value indicates that the vehicle is traveling approximately in a straight line.
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Accused Products
Abstract
A method calculates Euler'"'"'s rotation angles used to transform sampled values from a referred coordinate frame of a three-axis accelerometer device fixed to a vehicle to a reference coordinate frame of the vehicle. The method determines two rotation angles while the vehicle is still and assumed not inclined with respect to gravity, so that only the transformed value corresponding to a vertical axis of the vehicle equals acceleration due to gravity. Then, data acquired from the sensors typically during a braking event and indicated by a vehicle diagnostic system, along with the other two rotation angles, are used in the first derivative of a second Euler'"'"'s rotation equation to determine the remaining rotation angle. Data from the sensors is transformed by the three angles to the vehicle'"'"'s coordinate frame and correlated with acceleration data derived from the diagnostic system to verify the rotation angles.
78 Citations
20 Claims
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1. A method for automatically aligning three accelerometer axes corresponding to an accelerometer device coordinate frame with three vehicle axes corresponding to a coordinate frame of a vehicle, comprising:
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determining second and third rotation angles; retrieving a course signal value from a positioning circuit associated with the accelerometer device; and determining a first rotation angle when the course signal value indicates that the vehicle is traveling approximately in a straight line. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. An accelerometer device configured to perform a method for automatically aligning three accelerometer axes corresponding to an accelerometer device coordinate frame with three vehicle axes corresponding to a coordinate frame of a vehicle, the steps of the method comprising:
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determining second and third rotation angles; retrieving a course signal value from a positioning circuit associated with the accelerometer device; and determining a first rotation angle when the course signal value indicates that the vehicle is traveling approximately in a straight line. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19, 20)
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Specification