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TitleA personal inertial-navigation system based on multiple distributed, nine-degrees-of-freedom
Author
LanguageEnglish
File Size14.4 MB
Total Pages168
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Page 1

Calhoun: The NPS Institutional Archive

DSpace Repository

Theses and Dissertations 1. Thesis and Dissertation Collection, all items

2016-12

A personal inertial-navigation system based

on multiple distributed,

nine-degrees-of-freedom, inertial

measurement units

Johnson, Cole C.

Monterey, California: Naval Postgraduate School

http://hdl.handle.net/10945/51727

Page 2

NAVAL

POSTGRADUATE

SCHOOL


MONTEREY, CALIFORNIA






THESIS





Approved for public release. Distribution is unlimited.

A PERSONAL INERTIAL-NAVIGATION SYSTEM

BASED ON MULTIPLE DISTRIBUTED,

NINE-DEGREES-OF-FREEDOM, INERTIAL

MEASUREMENT UNITS



by



Cole C. Johnson



December 2016



Thesis Advisor: Xiaoping Yun

Second Reader: James Calusdian

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Figure 20. 2×1 Sensor Brackets, Left-Foot Bracket (Left) and Right-Foot Bracket
(Right)

Brackets were laced to the shoe at the lower instep, just above the intersection of

the arch and ball of the foot, as displayed in Figure 21. While the modules may appear to

pop out easily, they are tightly secured by the bracket’s sidewalls. Only one sensor

module came loose in 20 laps of testing.





Figure 21. Right-Foot 2×1 Bracket Holding Two IMUs

The first test setup incorporated two 2×1 brackets, each holding two 3-Space

modules as shown in Figure 20. For all foot-based testing, sensor modules 1 and 2 were

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mounted on the left foot and modules 3 and 4 on the right. This was done to enable

proper comparison between test runs, simplify comparison of the performance

differences among individual sensors on the same foot, and ascertain the benefits of

averaging co-located sensors.

The second test setup used a 2×2 bracket to co-locate four sensors, as shown in

Figure 22, allowing a near-identical force environment in which sensors were compared

directly and two to four sensors were fused into a single averaged output.





Figure 22. 2×2 Sensor Bracket Holding Four IMUs in Fixed Relationship

The 2×2 bracket was placed on the right foot and, like the 2×1 version, secured by

shoelaces as shown in Figure 23. Throughout all test events, only one test run was

aborted because the bracket came unhooked. No damage was observed to any

component.

Despite being rigid, there may have been some flexure in this and any of the other

brackets. This may have contributed to each IMU feeling a slightly different force and

subsequently needing slightly different PNS settings, which will be discussed later, to

achieve best performance. In addition, each IMU was in a different physical location and

could have had small discrepancies in the experienced forces. More than likely, these and

several other small contributing factors cause discrepancies between individual IMUs as

well as their mounted locations.

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