Apparatus and methodology for calibration of a gyroscope and a compass included in a handheld device
First Claim
1. A method comprising:
- rotating a handheld device through an angle of rotation defined by an initial position of the handheld device and a final position of the handheld device;
receiving rotation information from a three axis gyroscope;
integrating the rotation information from the three axis gyroscope over the angle of rotation in three dimensions to provide a rotation matrix describing rotation of the handheld device through the angle of rotation;
receiving a first magnetic vector information corresponding to the initial position of the handheld device and a second magnetic vector information corresponding to the final position of the handheld device from a three axis compass;
identifying a bias error of the three axis compass by comparing the rotation matrix to the first magnetic vector information and the second magnetic vector information; and
correcting the bias error of the three axis compass.
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Accused Products
Abstract
Techniques for estimating compass and gyroscope biases for handheld devices are disclosed. The compass bias can be determined by causing a small movement of the handheld device and comparing the data obtained from the compass with the data obtained from the gyroscope. The gyroscope bias can be determined by obtaining a quaternion based angular velocity term of the handheld device when the accelerometer and compass data are reliable, and then comparing the angular velocity term with the gyro data to estimate the gyro bias. When the compass and/or the accelerometer data are unreliable, a previously determined quaternion angular velocity term is used. The gyroscope bias can also be determined by measuring gyroscope biases at various temperatures in a non-factory setting, storing the data in a memory, and using the data to estimate gyro biases when the accelerometer and/or the compass data are unreliable.
23 Citations
19 Claims
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1. A method comprising:
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rotating a handheld device through an angle of rotation defined by an initial position of the handheld device and a final position of the handheld device; receiving rotation information from a three axis gyroscope; integrating the rotation information from the three axis gyroscope over the angle of rotation in three dimensions to provide a rotation matrix describing rotation of the handheld device through the angle of rotation; receiving a first magnetic vector information corresponding to the initial position of the handheld device and a second magnetic vector information corresponding to the final position of the handheld device from a three axis compass; identifying a bias error of the three axis compass by comparing the rotation matrix to the first magnetic vector information and the second magnetic vector information; and correcting the bias error of the three axis compass. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A handheld consumer electronics device comprising:
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a three axis gyroscope; a three axis compass; a memory that stores computer executable instructions; and a processor that facilitates execution of the computer executable instructions to at least; receive information from the three axis gyroscope related to a rotation of the handheld consumer electronic device through an angle of rotation from a first point to a second point and information from the three axis compass comprising a first magnetic vector corresponding to the first point of the angle of rotation and a second magnetic vector corresponding to the second point of the angle of rotation; integrate the information from the three axis gyroscope over the angle of rotation in three dimensions to provide a rotation matrix describing the rotation; and identify a bias error of the three axis compass by a comparison of the rotation matrix to the first magnetic vector and the second magnetic vector. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19)
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Specification