INERTIAL AIDED POST PROCESSED KINEMATIC GPS FOR MARINE

POSITIONING

An Overview of POSPac MMS

Lou Nash, Measutronics Corporation www.Measutronics.com

We too have a lot to cover in a minimal amount of time…

Please hold questions & comments until the end

CURRENT & “TIMELY”

"I had 5 seconds before you interrupted me." -- Barack Obama, 1ST 2012 Presidential Debate 10/3/12

This presentation provides an overview of how GNSS phase observations and

inertial data are used to provide a highly accurate post processed navigation

solution

OVERVIEW: Hardware & Software

In a nutshell… GPS PHASE DATA

INERTIAL DATA

TIME TAGGED VESSEL

ORIENTATION FILE

Inertial Aided Post Processed Kinematic (IAPPK) GPS

Navigation Solution

• POST PROCESSED VIRTUAL REFERENCE STATION (PPVRS) SOLUTION

BASED ON TRIMBLE’S VRSTM TECHNOLOGY

• SmartBaseTM QUALITY CHECK

• INERTIALLY- AIDED KINEMATIC AMBIGUITY RESOLUTION (IAKAR)

• IN-FusionTM: TIGHTLY COUPLED GNSS / INS SOLUTION

Summarized as a Four Step Process

1

2

3

4

POST PROCESSED VIRTUAL REFERENCE STATION (PPVRS)

BASED ON TRIMBLE’S VRSTM TECHNOLOGY

1 PPVRS

GPS: Relative Positioning

< 30 km* > 30 km * SEE SPECS PER RECEIVER TYPE

VRS Solutions Reduce Relative Positioning Errors

NMEA OUT

GGA

CMR IN

• A linked network of reference stations • Performs quality control / integrity monitoring of networked stations & their data streams • Models systematic errors within the network • Provides real time broadcast of true network RTK solution – ZERO BASELINE SOLUTION • Logs files for post processing • ESTABLISHES A COMMON REFERENCE DATUM

What is a VRSTM?

2 Applanix SmartBaseTM

RAW DATA

POTENTIAL PPVRS NETWORK

STATION SELECTION

INFO

STATION COORDINATE

INFO

Control Station Verification

SmartBaseTM Network Adjustment

PPVRS READY!

MINIMALLY / FULLY CONSTRAINED NETWORK

ADJUSTMENT

VRS SOLUTION “THROUGHOUT SURVEY

TIMELINE”

QA / QC & PPVRS READY

3 IAKAR

INERTIALLY- AIDED KINEMATIC AMBIGUITY RESOLUTION

• SINGLE KALMAN FILTER* ESTIMATES BOTH INERTIAL & GNSS ERRORS

• RAPID AMBIGUITY RESOLUTION: OUTAGES, MULTIPATH, ETC.

• AMBIGUITY “MEMORY”

* A KALMAN FILTER IS AN EFFICIENT RECURSIVE FILTER THAT ESTIMATES THE STATE OF A LINEAR DYNAMIC SYSTEM FROM A

SERIES OF NOISY MEASUREMENTS

ITERATIVE FILTER

GPS – vs - INERTIAL

A B

TIME

SHORT TERM

HUGE OVER-SIMPLICATION!!!

HUGE OVER-SIMPLICATION!!!

A B

TIME

GPS

LONG TERM

IN-FusionTM

• TIGHTLY COUPLED GNSS / INS PROCESSOR

• OPTIMIZED BY USING SmartBaseTM SOLUTION

PPVRS & INERTIAL

PROCESSING GNSS & INERTIAL, FWD & BACKWARD

EXPORT FILE

TYPICAL PROJECT

-Manual tide reading are only accurate within close proximity of gauge.

-Incapable of accounting for phase lag resulting from extrapolated tide gauges.

-Offshore borrow site

-Phase lag errors introduced into survey data

12 miles Phase difference 12 miles from tide gauge

ERROR IN TIDE READING

Offshore Borrow Site Surveys

OFFSHORE BORROW SITE

Offshore borrow site with NOAA tidal reductions 12 miles away

Offshore borrow site with post-processed tidal reductions using SBET for RTK Tides in HYPACK

125’ single beam cross sections gridded at 25’

125’ single beam cross sections gridded at 25’

NOT JUST A MULTIBEAM TOOL!!!

TYPICAL PROJECT

COMPARISON TEST

QUESTIONS?