A personal navigation system based on inertial and magnetic field measurements

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Authors
Calusdian, James
Subjects
personal navigation
accelerometer
magnetometer
angular rate sensor
quaternion
complementary filter
zero-velocity update
gait-phase detection algorithm
Advisors
Yun, Xiaoping
Date of Issue
2010-09
Date
September 2010
Publisher
Monterey, California. Naval Postgraduate School
Language
Abstract
This work describes the development and testing of a personal navigation system (PNS) for use during normal walking on level ground surfaces. A shoe-worn miniature inertial/magnetic measurement unit (IMMU), which is comprised of accelerometers, magnetometers, and angular rate sensors, provides the measurement data for the PNS algorithm. The well-known strapdown navigation algorithm is adapted for use in the PNS, which further incorporates the error correction technique commonly referred to as zero-velocity updates. A gait-phase detection algorithm estimates instances of foot stance and swing and establishes the appropriate times to apply the velocity error correction technique within the PNS algorithm. A main contribution of the work described herein pertains to the design and analysis of a quaternion-based complementary filter for estimation of three-dimensional attitude of the IMMU. This complementary filter algorithm builds on an earlier threedimensional attitude estimator known as the Factored Quaternion Algorithm (FQA). The complementary filter is further tailored for the PNS application through the use of an adaptive gain switching strategy based on knowledge of the gait phase. A novel and incidental effort described here pertains to the design and implementation of a locomotion interface for a virtual environment using the shoe-worn IMMU. In this application, one IMMU is worn on each foot. A set of foot gestures was conceived and a custom software program was developed to decode the user's foot motions. This unique interface gives the user freedom to navigate through a virtual environment in any direction he/she chooses for those applications utilizing large-screen displays.
Type
Description
Series/Report No
Department
Electrical Engineering
Organization
Identifiers
NPS Report Number
Sponsors
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Format
xxiv, 209 p. : col. ill. ; 28 cm.
Citation
Distribution Statement
Rights
This publication is a work of the U.S. Government as defined in Title 17, United States Code, Section 101. Copyright protection is not available for this work in the United States.
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