Zentimeter-genaue Satellitennavigation für Autonomes Fahren...2020/03/03 · EIKON...

Technische Universität München Advanced Navigation Solutions

Zentimeter-genaue Satellitennavigation für Autonomes Fahren

Patrick Henkel

EIKON Mitgliederversammlung

Dienstag, den 3.03.2020


Overview

Introduction to Precise Positioning with Global Navigation Satellite Systems (GNSS)

Fast Precise Point Positioning with Next-Generation GNSS Kepler

Sensor Fusion Architectures for Autonomous Driving

Snow Monitoring with GNSS carrier phase measurements


Satellite Navigation with Centimeter Accuracy – Fields of Application

Automotive Robotics and Automation

UAVs

Maritime

Surveying Snow Monitoring


Ranging with code signals

Ionosphäre

Troposphäre

Challenges for ranging:

- clock errors

are multiplied by speed of light

- atmosphere delays signal

and causes ranging errors

of up to 100 m

received time transmit time

Pseudorange:


Accurate ranging with carrier phase measurement

Phase Locked Loop (PLL)

for carrier phase tracking

Ionosphäre

Troposphäre

Satellite orbit

and clock errors

Receiver-specific errors:

- multipath errors

- measurement noise

- systematic errors (biases)

- antenna phase center offsets

- Earth tides

wavelength: 19 cm

Challenges for carrier phase:

- ambiguous measurement

to periodicity of carrier phase

- need to estimate/ know lumped sum

of all ranging errors with an accuracy

of a small fraction of the wavelength


Accurate positioning with carrier phase measurement

smallest error norm


Real-Time Kinematic (RTK) Positioning

- differential positioning between two receivers

to eliminate common atmospheric delays

and satellite-related errors (orbits, clocks and biases)

- use of both pseudorange

and carrier phase measurements

- fixing of integer ambiguities

RTK Positioning



State prediction State update

Kalman filter-based state estimation:

Ambiguity fixing:


Real-Time Kinematic (RTK) Positioning: Integer Ambiguity Fixing

Graphical description

of ambiguity fixing



Distancetoreferencestation

duringinitialization

accuracy level



Single pointpositioning

Multi-Sensor RTK solution


The Challenge of Absolute Precise Point Positioning (PPP)

Carrier phase measurement

at receiver on frequency of satellite at time :

unknown parameters determined by PPP user

parameters provided by satellite navigation message

parameters provided by a model

corrections determined by a network of geodetic reference stations


Next Generation GNSS - Kepler

GALILEO KEPLER

optical

inter-satellite links

Advantages:

- more accurate ranging

- much better geometry

- negligible clock errors


Precise Point Positioning with Kepler – System Overview

Simulation

of orbits

Recovery

of orbits

Simulation of

carrier phase and

pseudorange measurements

on E1, E5 and E6

Kinematic PPP solution

with Kalman filterAmbiguity fixing

Receiver trajectory, models,

process noise and measurement noise statistics

by Geoforschungszentrum

Potsdam (GFZ)

by Geoforschungszentrum

Potsdam (GFZ)


Static versus kinematic PPP – estimated state parameters

Static PPP Kinematic PPP

Receiver position

Receiver velocity

Receiver clock offset

Tropospheric zenith delay

Ionospheric slant delays

Integer ambiguities

Pseudorange multipath errors


Performance evaluation – Statistical Assumptions

• Process noise statistics – standard deviations:

• Measurement noise statistics – standard deviations:


Receiver trajectory with high dynamics


Satellite orbits from GFZMismodelling effects:

1. Ocean loading model

deactivated

2. Solid Earth tide model

IERS Conv. 2003 replaced by IERS Conv. 1996

3. Gravity field

EIGEN-6 replaced by EIGEN-5

4. LEO air drag model

solar flux error (previous day value)

5. MEO antenna thrust

deactivated

6. MEO solar radiation pressure

ECOM 9 replaced by ECOM 5

7. LEO solar radiation pressure

polygon scaling factor introduced

8. GNSS antenna PCOs

MEOs: north/ east +3 cm, up +5 cm added

LEOs: Along-track +3 cm, cross-track +4 cm.


Satellite orbits – Impact of number of ground stations on orbit accuracy


Performance Analysis of Receiver Position Estimation

- Galileo versus Kepler (with 18 ground stations)

No ambiguity fixing achieved!

Ambiguities fixed!


Performance Analysis of Receiver Position Estimation

- Galileo (18GS-7MIS-P1) versus Kepler (1GS-7MIS-P1)


Ambiguities fixed!


Performance Analysis of Receiver Clock Offset Estimation

- Galileo versus Kepler


Ambiguities fixed!


Performance Analysis of Tropospheric Zenith Delay Estimation


Ambiguities fixed!



Performance Analysis of Ionospheric Slant Delays Estimation


Ambiguities fixed!



Performance Analysis with Kepler – 2F (E1+E5) versus 3F (E1+E5+E6)

Ambiguities fixed!



Performance Analysis with Kepler – 2F (E1+E5):

The potential benefit of a wideband signal on E1.

Significant reduction in fixing time!


Accurate and robust localization for autonomous driving

Focus of today


Advanced Sensor Fusion Architectures with Artificial Intelligence

Focus of today


Snow Monitoring with GNSS (GPS + Galileo)

Perform differential pseudorange

and carrier phase measurements

to eliminate atmospheric errors

Correct differential measurements

for known receiver and satellite positions

Estimate Snow Water Equivalent

and Carrier Phase Integer Ambiguities

GNSS receiver below snow

GNSS reference

receiver above snow



08.12.2018 with SWE of 116 mm08.10.2018 with SWE of 0 mm



10.02.2019 with SWE of 675 mm08.10.2018 with SWE of 0 mm




Conclusion

Introduction to Precise Positioning with Global Navigation Satellite Systems (GNSS)

Fast Precise Point Positioning with Next-Generation GNSS Kepler

Sensor Fusion Architectures for Autonomous Driving

Snow Monitoring with GNSS carrier phase measurements

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Zentimeter-genaue Satellitennavigation für Autonomes Fahren...2020/03/03 · EIKON...

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