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www.DLR.de • Chart 1 >Resilient PNT: From PNT Unit concept to first realization> R. Ziebold > e-Navigation Underway 01/30/2013
Resilient PNT:
From PNT-Unit concept to first realization
Ralf Ziebold, Z. Dai, L, Lanca, D. Minkwitz, T. Noack, E. Engler
German Aerospace Centre
Institute of Communications and Navigation
Nautical Systems Group
www.DLR.de • Chart 2 >Resilient PNT: From PNT Unit concept to first realization> R. Ziebold > e-Navigation Underway 01/30/2013
PNT relevant user needs within E-Navigation
PNT information
Improved
reliability
Indication of
reliability Alert
management
IMO, NAV 55/WP.5
PNT System Generic Architecture
INS
ship-side components
Augmentation Services
- 1 … N
PNT relevant MSP
etc.
PNT relevant MSI
Backup Services
- 1 … K
World Wide Radio Navigation Systems (WWRNS)
shore-side services links
functional
links
physical
links PNT Module PNT Module
MGBAS Service (Research Port Rostock)
www.DLR.de • Chart 4 >Resilient PNT: From PNT Unit concept to first realization> R. Ziebold > e-Navigation Underway 01/30/2013
Integrity definitions
- IMO Integrity Definition: (IMO Resolution A.915(22) Requirements for a future GNSS)
The ability to provide users with warnings within a specified time when the system should
not be used for navigation
Integrity: timely (TTA) warning, based on accuracy estimation
Protection level (PL): bounds true error under consideration of
remaining integrity risk
Available: PL < Alert limit (AL)
Continuity
Availability
General structure of GNSS service specification
Accuracy: The degree of conformance between the estimated
or measured parameter of a craft at a given time and its true
parameter at that time. (95% confidence)
www.DLR.de • Chart 5 >Resilient PNT: From PNT Unit concept to first realization> R. Ziebold > e-Navigation Underway 01/30/2013
From service to user level integrity
Current user level integrity definition
- IEC INS standard (61924:2006)
property of information as being accurate and valid with regard to specified requirements
and verified by comparing data from more than one independent source
1st. Approach: Establish user level integrity comparable to GNSS service specification (based on accuracy estimation) onboard the vessel
=> Over bound all possible errors (threads)
large gap between service level integrity and user level integrity
www.DLR.de • Chart 6 >Resilient PNT: From PNT Unit concept to first realization> R. Ziebold > e-Navigation Underway 01/30/2013
PNT Unit Approach
Shipboard
Sensor Layer
Shipboard
Processing Layer
GNSS Receiver
DGNSS Receiver
Multi Radio Navigation
Receiver
etc.
WWRNS
sensors
Gyro / Compass
Speed / Log
Other
shipboard
sensors
etc.
ROTI
interface, point of type approval
PVT
PVT
PVT
N
N
N
PNT
(data processing)
Unit
as
part of INS
best PNT
Integrity
(accuracy)
Alerts
Other PNT relevant Input Data
(Radar, MSI, AIS,…)
raw
raw
raw
raw
raw
raw
www.DLR.de • Chart 7 >Resilient PNT: From PNT Unit concept to first realization> R. Ziebold > e-Navigation Underway 01/30/2013
Measurement campaigns
- Survey and research vessel DENEB (BSH)
First experimental results
(2)
(3)
(1)
Additional sensors
- Tactical grade IMU
- 3x GNSS receiver
(dual frequency RTK)
www.DLR.de • Chart 8 >Resilient PNT: From PNT Unit concept to first realization> R. Ziebold > e-Navigation Underway 01/30/2013
-50 0 50 100 150 200
0
500
1000
1500
2000
2500
3000
3500
4000
East [m]
No
rth
[m
]
Trajectory with respect to the starting point
GPS only
GPS/IMU Integration
10: 9 10:17 10:25 10:34 10:42 10:50 10:590
5
10
15
20
25
30
Local time [hour:minute]
Ab
so
lute
err
or
[m]
Horizontal error with respect to the reference trajectory
GPS only
GPS/IMU Integration
Tightly-coupled GPS/IMU
integration with satellite filtering Accuracy improvement
Tightly coupled GPS/IMU
www.DLR.de • Chart 9 >Resilient PNT: From PNT Unit concept to first realization> R. Ziebold > e-Navigation Underway 01/30/2013
Innovation of satellites
E a s tW e s t
N o rth
S o u th
3
5
6
7
8
1 0
1 3
1 5
1 9
2 1
2 6
2 8
Spurious Measurements
10:1 10:30 10:59-10
0
10PRN: 3
10:1 10:30 10:59-10
0
10PRN: 5
10:1 10:30 10:59-10
0
10PRN: 7
10:1 10:30 10:59-10
0
10PRN: 8
10:1 10:30 10:59-10
0
10PRN: 10
10:1 10:30 10:59-10
0
10PRN: 13
10:1 10:30 10:59-10
0
10PRN: 15
10:1 10:30 10:59-10
0
10PRN: 19
10:1 10:30 10:59-10
0
10PRN: 21
10:1 10:30 10:59-10
0
10PRN: 26
Innovation Code X-axis: GPS epochs Y-axis: Innovation in meters
10:1 10:30 10:59-10
0
10PRN: 28
Satellites with low elevation angles
Cancellation
www.DLR.de • Chart 10 >Resilient PNT: From PNT Unit concept to first realization> R. Ziebold > e-Navigation Underway 01/30/2013
-250 -200 -150 -100 -50 0 50 100-100
-50
0
50
100
150
200
East [m]
Nort
h [m
]
Trajectory with respect to the starting point
GPS only
GPS/IMU (sat. filter)
GPS/IMU (no sat. filter)
Dynamic model (herein IMU) can
smooth the positioning results
Integration with/without satellite filtering
Integrity monitoring on each
measurement has dominant effects
in the accuracy improvement
IMU contingency functionality
www.DLR.de • Chart 11 >Resilient PNT: From PNT Unit concept to first realization> R. Ziebold > e-Navigation Underway 01/30/2013
50 100 150 200 2500
2
4
6
8
10
Pos E
rr [
m]
Epoch [s]
50 100 150 200 2500
0.2
0.4
0.6
0.8
1
Vel E
rr [
m/s
]
-6 -4 -2 0 2 4 60
200
400
600
East [m]
Notr
h [
m]
GPS/IMU
RTK
IMU only
50 100 150 200 2500
2
4
6
8
10
Pos E
rr [
m]
Epoch [s]
50 100 150 200 2500
0.2
0.4
0.6
0.8
1
Vel E
rr [
m/s
]
-50 -40 -30 -20 -10 0 100
200
400
600
East [m]
Notr
h [
m]
GPS/IMU
RTK
IMU only
50 100 150 200 2500
2
4
6
8
10
Pos E
rr [
m]
Epoch [s]
50 100 150 200 2500
0.2
0.4
0.6
0.8
1
Vel E
rr [
m/s
]
120 140 160 180 200 220 240 260 280 300150
200
250
300
350
East [m]
Notr
h [
m]
GPS/IMU
RTK
IMU only
~10m position error with
tactical grade IMU
Next step: GNSS / IMU / speed log
integration
- tightly coupled IMU / GNSS stand alone
-1 min GNSS outage
Accuracy estimation
www.DLR.de • Chart 12 >Resilient PNT: From PNT Unit concept to first realization> R. Ziebold > e-Navigation Underway 01/30/2013
1105 1110 1115 1120 1125 11300
5
10
15
20
25
30
35
Minutes of Day (minutes)
HPL [meters]
Horizontal Estimation Error (95%) [meters]
Horizontal Real Error [meters]
Number of Visible Satellites
Num
be
r o
f sa
telli
tes
15
10
5
Ho
rizo
nta
l e
rro
r [m
]
0
- adaptation of existing RAIM algorithm
(developed for aviation sector) to
maritime requirements
IMO
A.915(22)
Alert Limit
GPS single frequency stand alone positioning
www.DLR.de • Chart 13 >Resilient PNT: From PNT Unit concept to first realization> R. Ziebold > e-Navigation Underway 01/30/2013
PNT Unit interface
Open question:
Input interface - accuracy, integrity, continuity, availability for all PNT paramter
depended on the operational region
How this information about current operational region is transferred to PNT Module?
- ENC layer ? Output interface: - What integrity information should be delivered how?
www.DLR.de • Chart 14 > IALA Beacon DGNSS Monitoring Service > D. Minkwitz & MVT-Team • Date
Currently available MGBAS Services at Research Port
Rostock for Validation of aboard PNT-unit
RTCM Messages
via Radio Modem
Corrections
Information
Inte
grity
www.DLR.de • Chart 15 > IALA Beacon DGNSS Monitoring Service > D. Minkwitz & MVT-Team • Date
MGBAS: RTK Services
Goal: fulfill IMO’s port requirements regarding
accuracy, integrity, continuity and availability
Status:
two GPS-based RTK services
GALILEO-based and multi-GNSS services
in preparation
Minimum Requirements on Future GNSS Extract of IMO A.915(22)
www.DLR.de • Chart 16 > IALA Beacon DGNSS Monitoring Service > D. Minkwitz & MVT-Team • Date
MGBAS: IALA Beacon Monitoring Service
DGNSS Station (ID: 761) MGBAS as integrity monitor for RTCM2 messages
Assessment of IALA beacon DGNSS corrections as backup
for RTK services
2.55 2.6 2.65 2.7 2.75 2.8 2.85
x 104
0
2
4
6
8
10
12
14
16
18
Hour 7 to 8, DOY 54 Year 2012
GPS Day Seconds
3D
Positio
n E
rror
[m]
no corrections
RTCM2 corrections of Groß Mohrdorf
www.DLR.de • Chart 17 >Resilient PNT: From PNT Unit concept to first realization> R. Ziebold > e-Navigation Underway 01/30/2013
Summary
- Initial realization of a sensor fusion based PNT Unit
=> improved integrity monitoring incl. accuracy estimation
=> IMU contingency functionality
- Open questions:
- clear definition of user level integrity
- input: operational region
- output: HMI for integrity information
- Shore base services at Research Port Rostock
- MGBAS (RTK) service for high precision application
- IALA Beacon monitor
www.DLR.de • Chart 18 >Resilient PNT: From PNT Unit concept to first realization> R. Ziebold > e-Navigation Underway 01/30/2013
Thank You For Your Attention !
© Hafenentwicklungsgesellschaft Rostock mbH
e-mail Ralf.Ziebold@DLR.de
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