Determining sensor orientation in indoor navigation
First Claim
1. A method for determining a crab angle of a portable electronic device carried by a user, wherein the crab angle is an angle by which the device direction of travel differs from the device orientation, and wherein the device is provided with a vector accelerometer, the method comprising:
- detecting a step of the user at a fixed phase of the user'"'"'s step cycle using the vector accelerometer and acquiring a plurality of acceleration vectors;
projecting each acceleration vector into a horizontal plane that is perpendicular to a vertical direction;
determining an energy vector for each projected acceleration vector over one step cycle; and
computing the device crab angle by finding a direction in the horizontal plane having maximal energy associated therewith.
2 Assignments
0 Petitions
Accused Products
Abstract
A method and system are provided for improved pedestrian dead reckoning. In an embodiment, the crab angle of a device, i.e., the angle by which the device direction of travel differs from the device orientation, is determined via the processing of measurements from a vector accelerometer. The measured acceleration vector is rotated so that one component is vertical, and the crab angle is then found by determining a horizontal direction having the greatest energy. Correlations between the two horizontal acceleration components and the vertical acceleration component may be computed to determine the user'"'"'s gait, further improving dead reckoning, e.g., for improving indoor position resolution.
5 Citations
12 Claims
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1. A method for determining a crab angle of a portable electronic device carried by a user, wherein the crab angle is an angle by which the device direction of travel differs from the device orientation, and wherein the device is provided with a vector accelerometer, the method comprising:
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detecting a step of the user at a fixed phase of the user'"'"'s step cycle using the vector accelerometer and acquiring a plurality of acceleration vectors; projecting each acceleration vector into a horizontal plane that is perpendicular to a vertical direction; determining an energy vector for each projected acceleration vector over one step cycle; and computing the device crab angle by finding a direction in the horizontal plane having maximal energy associated therewith. - View Dependent Claims (2, 3, 4, 5, 6, 8, 9, 10)
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7. A portable electronic device that provides pedestrian dead reckoning, the portable electronic device comprising:
- an accelerometer for detecting an acceleration vector; and
a processor, the processor being configured to detect a step of a user at a fixed phase of the user'"'"'s step cycle using the vector accelerometer and acquiring a plurality of acceleration vectors and project the acceleration vectors into a horizontal plane perpendicular to a vertical direction, determine an energy vector for each projected acceleration vector over one step cycle and compute a crab angle of the device by determining a direction in the horizontal plane with maximal energy, wherein the crab angle is an angle by which the determined direction differs from the device orientation. - View Dependent Claims (11, 12)
- an accelerometer for detecting an acceleration vector; and
Specification