trustworthy positioning for next generation intelligent ... university is a trademark of curtin...
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Curtin University is a trademark of Curtin University of Technology
CRICOS Provider Code 00301J
Trustworthy Positioning
for Next Generation
Intelligent Transport
Systems
Ahmed El-Mowafy
Curtin University is a trademark of Curtin University of Technology
CRICOS Provider Code 00301J
Curtin University is a trademark of Curtin University of Technology
CRICOS Provider Code 00301J
Contents
Background on ITS and C-ITS
Requirements
Challenges
RAIM
Test and Results
Japan-Australia Quasi-Zenith Satellite System (QZSS) Industrial
Utilisation Workshop, Sydney, 6 Feb. 2018. 2
Curtin University is a trademark of Curtin University of Technology
CRICOS Provider Code 00301J
Curtin University is a trademark of Curtin University of Technology
CRICOS Provider Code 00301J
ITS objectives
Make transportation safer, more efficient and reduce emissions
Efficiency
Safety
Emissions
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Curtin University is a trademark of Curtin University of Technology
CRICOS Provider Code 00301J
Curtin University is a trademark of Curtin University of Technology
CRICOS Provider Code 00301J
C-ITS
Source: Austroads, 2010
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Utilisation Workshop, Sydney, 6 Feb. 2018. 4
V2V and V2I
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Curtin University is a trademark of Curtin University of Technology
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Communication using DSRC. DSRC-based range-rating measurements can enable GNSS/DSRC cooperative positioning.
VANET (Vehicular ad hoc network)
C-ITS
Source: Internet
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Curtin University is a trademark of Curtin University of Technology
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Curtin University is a trademark of Curtin University of Technology
CRICOS Provider Code 00301J
• Road level (few m)
• Lane-level (< 1m)
• Where-in-lane level (sub-m)
Current systems mainly use SPS (Standard Positioning Service).
SPS gives 1-5 m accuracy - not suitable for lane-level precision.
Use of augmentation techniques, such as SBAS has the potential to
offer the required accuracy.
Most imported C-ITS uses SBAS technology.
Satellite positioning accuracy requirements
More accuracy is
needed
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Curtin University is a trademark of Curtin University of Technology
CRICOS Provider Code 00301J
Curtin University is a trademark of Curtin University of Technology
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But: Is it only accuracy we are interested in!
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Curtin University is a trademark of Curtin University of Technology
CRICOS Provider Code 00301J
Curtin University is a trademark of Curtin University of Technology
CRICOS Provider Code 00301J
Ex: Curtin University Driverless Buss
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Utilisation Workshop, Sydney, 6 Feb. 2018. 8
Curtin University is a trademark of Curtin University of Technology
CRICOS Provider Code 00301J
Curtin University is a trademark of Curtin University of Technology
CRICOS Provider Code 00301J
Accuracy VS Integrity
AL
Accuracy Integrity
Alert to driver/user
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PL
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Curtin University is a trademark of Curtin University of Technology
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Challenges
• Standards? need to be set based on performance requirements.
• Complete map of risks (e.g. collision types, faults, etc.)
and vulnerabilities (system errors, interference, jamming spoofing, etc.)
and identify their probabilities.
• Integration of sensors (GNSS is a main component but not alone)
• Cost
• Communications
• Application dependence.
• Technology.
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Curtin University is a trademark of Curtin University of Technology
CRICOS Provider Code 00301J
Curtin University is a trademark of Curtin University of Technology
CRICOS Provider Code 00301J
Example
of NLOS
Urban environment:
• Loss of lock
• Heavy multipath
• Non Line of Sight (NLOS)
• Frequent cycle-slips
Mitigations:
• Multipath mitigation at the antenna
• 3D city-models – ray-tracing algorithms
• SNR monitoring
• Non-Gaussian error models
• VANET CIM concept
Ex: Vulnerabilities due to the work environment
Use 3D city-
models
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Curtin University is a trademark of Curtin University of Technology
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Curtin University is a trademark of Curtin University of Technology
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Characterisation of errors (ex: clock corrections)
PRN16 PRN 29 PRN30
Histograms
Q-Q
CDF
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CRICOS Provider Code 00301J
Curtin University is a trademark of Curtin University of Technology
CRICOS Provider Code 00301J
GNSS Positioning Methods
Baseline length
100km 1,000km 10,000km 10km Worldwide
10cm
20cm
40cm
60cm
80cm
1m
PPP
4cm
RTK
Acc
ura
cy
SBAS DGNSS
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Curtin University is a trademark of Curtin University of Technology
CRICOS Provider Code 00301J
Curtin University is a trademark of Curtin University of Technology
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SBAS
GEO Satellites
SBAS
SBAS
Ionosphere
Troposphere
Reference
stations
Vulnerabilities linked to
hardware, software and
data link with the satellites
• Improved positioning:
sub-m (DGPS L1, L1/L5)
deci-metre (PPP)
• Integrity monitoring: error bounds for PL
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Utilisation Workshop, Sydney, 6 Feb. 2018. 14
Curtin University is a trademark of Curtin University of Technology
CRICOS Provider Code 00301J
Curtin University is a trademark of Curtin University of Technology
CRICOS Provider Code 00301J
Integrity monitoring
Advanced RAIM (ARAIM)
• Fault Detection & Exclusion based on
statistical hypothesis testing
• PLs computation based on estimated
impact of faults on position solution
Determine Protection Levels (PLs) as
safety bounds to positioning errors
• Take into account risk of
anomalies/faults
• PLs must be smaller than the Alert
Limits (ALs) to guarantee availability
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Curtin University is a trademark of Curtin University of Technology
CRICOS Provider Code 00301J
Curtin University is a trademark of Curtin University of Technology
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For standalone vehicle
Multi-sensor
V2V and V2I .
ARAIM
Multi-sensor integration
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AT
CT
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Curtin University is a trademark of Curtin University of Technology
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Testing Ex.
• Kinematic test in Tokyo (with TUMSAT)
• Trimble RTK (10Hz)
• GPS, GLONASS and BeiDou
• a Bosch-consumer grade MEMS IMU
The heading error of this IMU ranged
from -2o to 5o, can accumulate to 10o
after 30 min if left uncalibrated.
• Speed sensor: s = 5 cm/s
• GNSS-Doppler: s = 10 cm/s.
• Reference : PPK & POS/LV
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Testing: challenging environment
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Integrity prediction
Along Track Cross Track
Identify critical locations on the map, at
different times of the day
Integrity unavailable: red points (PL>AL)
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Curtin University is a trademark of Curtin University of Technology
CRICOS Provider Code 00301J
Curtin University is a trademark of Curtin University of Technology
CRICOS Provider Code 00301J
Actual data: Flow chart of sensor fusion (RTK, IMU, odometer)
Computes heading
from GNSS Doppler
Meets GNSS
heading
Conditions
Yes
Update heading of the
IMU (GNSS & ZUPT)
Computes positions
from Speed of Speed
sensor and IMU
heading
No
Doppler
available
Yes
RTK
available
No
Yes
Computes
positions using
RTK
Yes
Compute velocity from
GNSS Doppler
Compute positions
from GNSS velocity
Meets GNSS
Velocity
Conditions
No
Output position
No
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1 2 3
Curtin University is a trademark of Curtin University of Technology
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Curtin University is a trademark of Curtin University of Technology
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Protection levels
𝑃𝐿𝐴𝑇,𝑖 = 𝐾𝑓𝑎,𝑖
𝜎𝛿𝐴𝑇,𝑖 + 𝐾𝑚𝑑,𝑖 𝜎𝐴𝑇,𝑖 + (cos 𝜃 𝑎1𝑇 𝑆𝑖 × 𝑏𝑜)2+ (sin 𝜃 𝑎2
𝑇 𝑆𝑖 × 𝑏𝑜)2
𝑃𝐿𝐶𝑇,𝑖 = 𝐾𝑓𝑎,𝑖
𝜎𝛿𝐶𝑇,𝑖 + 𝐾𝑚𝑑,𝑖 𝜎𝐶𝑇,𝑖 + (sin 𝜃 𝑎1𝑇 𝑆𝑖 × 𝑏𝑜)2+ (cos 𝜃 𝑎2
𝑇 𝑆𝑖 × 𝑏𝑜)2
𝑃𝐿𝐴𝑇,𝑖 = 𝐾𝑚𝑑,𝑖 𝜎𝐴𝑇,𝑖 + (cos 𝜃 𝑎1𝑇 𝑆
𝑏𝜃𝐼𝑀𝑈
𝑏𝑣)2+ (sin 𝜃 𝑎2
𝑇 𝑆 𝑏𝜃𝐼𝑀𝑈
𝑏𝑣)2
𝑃𝐿𝐶𝑇,𝑖 = 𝐾𝑚𝑑,𝑖 𝜎𝐶𝑇,𝑖 + (sin 𝜃 𝑎1𝑇 𝑆
𝑏𝜃𝐼𝑀𝑈
𝑏𝑣)2+ (cos 𝜃 𝑎2
𝑇 𝑆 𝑏𝜃𝐼𝑀𝑈
𝑏𝑣)2
RTK
IMU+odometre
𝑃𝐿𝐴𝑇,𝑖 = 𝐾𝑚𝑑,𝑖 𝜎𝐴𝑇,𝑖 + (cos 𝜃 𝑎1𝑇 𝑆
𝑏𝑣𝐸
𝑏𝑣𝑁
)2+ (sin 𝜃 𝑎2𝑇 𝑆
𝑏𝑣𝐸
𝑏𝑣𝑁
)2
𝑃𝐿𝐶𝑇,𝑖 = 𝐾𝑚𝑑,𝑖 𝜎𝐶𝑇,𝑖 + (sin 𝜃 𝑎1𝑇 𝑆
𝑏𝑣𝐸
𝑏𝑣𝑁
)2+ (cos 𝜃 𝑎2𝑇 𝑆
𝑏𝑣𝐸
𝑏𝑣𝑁
)2
Doppler
Japan-Australia Quasi-Zenith Satellite System (QZSS) Industrial
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biases
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RTK Results
G+R+B
G+B
G+R
G
* b = 1×10-4
AT CT
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Utilisation Workshop, Sydney, 6 Feb. 2018. 22
Curtin University is a trademark of Curtin University of Technology
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Curtin University is a trademark of Curtin University of Technology
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All sensors
Combined
Doppler
RTK
IMU+odometer
* b = 1×10-4 00.5
11.5
22.5
33.5
44.5
5
174250 174500 174750 175000
PL
& E
rro
r (
m)
Time (sec)
PL_AT (All) err_AT (All)
00.5
11.5
22.5
33.5
44.5
5
174250 174500 174750 175000
PL
& E
rro
r (
m)
Time (sec)
PL_CT (All) err_CT (All)
0
0.1
0.2
0.3
0.4
0.5
174250 174500 174750 175000
PL
& E
rro
r (
m)
Time (sec)
PL_AT (RTK) err_AT (RTK)
0
0.1
0.2
0.3
0.4
0.5
174250 174500 174750 175000
PL
& E
rro
r (
m)
Time (sec)
PL_CT (RTK) err_CT (RTK)
00.5
11.5
22.5
33.5
44.5
5
174250 174500 174750 175000
PL
& E
rro
r (
m)
Time (sec)
PL_AT (Doppler) err_AT (Doppler)
00.5
11.5
22.5
33.5
44.5
5
174250 174500 174750 175000
PL
& E
rro
r (
m)
Time (sec)
PL_CT (Doppler) err_CT (Doppler)
00.5
11.5
22.5
33.5
44.5
5
174250 174500 174750 175000
PL
& E
rro
r (
m)
Time (sec)
PL_AT (IMU+odo) err_AT (IMU+odo)
00.5
11.5
22.5
33.5
44.5
5
174250 174500 174750 175000
PL
& E
rro
r (
m)
Time (sec)
PL_CT (IMU+odo) err_CT (IMU+odo)
AT CT
Japan-Australia Quasi-Zenith Satellite System (QZSS) Industrial
Utilisation Workshop, Sydney, 6 Feb. 2018. 23
Curtin University is a trademark of Curtin University of Technology
CRICOS Provider Code 00301J
Curtin University is a trademark of Curtin University of Technology
CRICOS Provider Code 00301J
Summary
ITS / C-ITS might be the norm in the near future.
Real-time safety related applications in ITS/C-ITS require highly
trustworthy positioning: i.e. integrity monitoring.
The technology might not be the problem: cost and interoperability
might be.
Integrity Monitoring (IM) is challenging
IM can be achieved, but which standards? Applications?
Japan-Australia Quasi-Zenith Satellite System (QZSS) Industrial
Utilisation Workshop, Sydney, 6 Feb. 2018. 24