ee 495 modern navigation systems ins-gps integration architectures wednesday, april 09 ee 495 modern...

EE 495 Modern Navigation Systems

INS-GPS Integration Architectures

Wednesday, April 09 EE 495 Modern Navigation Systems Slide 1 of 9

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Wednesday, April 09 EE 495 Modern Navigation Systems

• Uncoupled GPS/INS Integration The most straight forward integration approach The GPS essentially repeatedly “initializes” the INS NOT error-space estimation

o Requires a dynamic model of the PVA of the host!!

Slide 2 of 9

IMU INSMechanization

v

Position, Velocity,

& Attitude

GNSSReceiver

GNSSProcessing

Position & Velocity

The GPS “resets” the INS




• Loosely-Coupled GPS\INS Integration: Open-Loop Transitions from a “full-state” to an “error-state” estimation

configuration Potentially “large” INS derived PVA errors can cause filter

divergence o Local-linearization assumptions may be violated

Slide 3 of 9


v

INS derived PVA

Corrected PVA

GNSSReceiver

GNSSProcessing

GNSS derived PV

Error-SpaceFilter

+

-

+

-

The INS mechanization errors are estimated




• Loosely-Coupled GPS\INS Integration: Closed-Loop Also an “error-state” estimation configuration Potential open-loop divergence problem addressed

o Estimates of the errors in the INS are fed back into the INS mechanization (e.g., accel & gyro bias estimates)

o Need to be careful how often feedback occurs (correlation)

Slide 4 of 9


v

Corrected PVA

GNSSReceiver

GNSSProcessing

GNSS derived PV

Error-SpaceFilter

+

-

-

The INS mechanization errors are estimated




• Tightly-Coupled GPS\INS Integration Also an “error-state” estimation configuration

o Errors NOT in PVA-domain – Use pseudorange errors– Can function with less than 4 GPS satellites

Slide 5 of 9


v

Corrected PVA

GNSSReceiver

TrackingLoops

GNSS derivedpseudo range

Error-SpaceFilter

+

-

Pseudo-rangeEstimation

IMU derivedpseudo range

The GPS aids the INS & the INS potentially aids the GPS

1 1

n n

GPS INS

GPS INS

H

z

x v




• Deeply-Coupled GPS\INS Integration INS aids the GPS carrier tracking loops

o Reduced bandwidth less noise & better jamming immunityo Substantial increase in computational complexity

Slide 6 of 9

Front End

Sampling

DopplerRemoval

Carrier NCOcos sin

Correlatorsone

for eachsatellite

Code Gen.

Clock NCO

Pre-FilterBank

one for each

satellite

Integrate&

Dump

IE

QE

IP

QP

IL

QL

MasterFilter

Error state vecone per sat.

Error Cov.one per sat.

Inertial Nav

SystemIMU

LOS projection,Pseudorange &

Pseudorange rates

Output: Position, Velocity and Attitude

0I

0Q

The GPS aids the INS & the INS aids the GPS


INS Only vs GPS Only


Inertial-Only Solution GPS-Only Solution


INS Only vs GPS-Aided Solution


Inertial-Only Solution GPS-Aided Solution


ee 495 modern navigation systems ins-gps integration architectures wednesday, april 09 ee 495 modern...

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