Post on 23-Jan-2023
4th International Conference on Machine Control & Guidance, March 19-20, 2014
1
Accuracy Assessment Study of GNSS Precise Point Positioning for
Kinematic Positioning
Ashraf Abdallah , Volker Schwieger
University of Stuttgart Institute of Engineering Geodesy (IIGS)
4th International Conference on Machine Control & Guidance, March 19-20, 2014
2
Structure
1. BASIC CONCEPTS
2. MOTIVATION
3. PROCESSING PROCEDURE
4. DATA ACQUSITION
5. RESULTS AND ANALYSIS
6. CONCLUSIONS
4th International Conference on Machine Control & Guidance, March 19-20, 2014
3
1. BASIC CONCEPTS• PPP technique is the method that using of only
one GNSS receiver for positioning.• Precise satellite orbits and clock corrections
(e.g. From IGS and JPL).
• Antenna phase center variations for satellite and receiver.
• Phase wind up, solid earth tides, ocean loading effect and earth rotation.
GPS Ephem eris IGS JPL
3-D RM S Accuracy (cm )
Latency 3-D RM S Accuracy (cm )
Latency
Ultra-Rapid (predicted) ~5 cm real time - - Ultra-Rapid (estim ated) <3 cm 3 hours 5 cm < 2 hours Rapid (estim ated) ~2.5 cm 17 hours 3.5 cm Next-Day (16:00 UTC) Final (estim ated) ~2.5 cm ~13 days 2.5 cm < 14 days
4th International Conference on Machine Control & Guidance, March 19-20, 2014
4
2. MOTIVATION
• Accuracy assessment study of kinematic PPP solution for two car kinematic trajectories .
• PPP solution Using GIPSY-OASIS software and CSRS-PPP online service.
• PPP solutions were evaluated with different periods of the initialization time (zero to sixty minutes); to establish the one needed reliable results.
4th International Conference on Machine Control & Guidance, March 19-20, 2014
5
3. PROCESSING PROCEDURE• Observation data.• Data quality check
using TEQC software.• Differential GNSS
solution using Leica Geo Office software with SAPOS reference station.
• Divide the initialization time using TEQC software [from 60 min to 00 min].
• PPP solution using GIPSY-OASIS software and CSRS-PPP online service.
4th International Conference on Machine Control & Guidance, March 19-20, 2014
6
3.1 GIPSY-OASIS software
• A scientific software for processing GPS data.
• published from JPL (Jet Propulsion Laboratory of NASA),
• deals with the static and kinematic GPS data.
4th International Conference on Machine Control & Guidance, March 19-20, 2014
7
3.2 CSRS-PPP Online Service• Offered from the
Natural Resources of Canada (NRC) for PPP solution.
• Single or dual frequency
• Static or kinematic data.
• One of the most famous PPP online services.
4th International Conference on Machine Control & Guidance, March 19-20, 2014
8
CSRS-PPP Online Service vs GIPSY-OASIS
4th International Conference on Machine Control & Guidance, March 19-20, 2014 9
3.3 Evaluation Methodology• Difference values () between the Leica Geo
Office PDGNSS results (M) as a reference solution and the PPP results (M’).
= M - M’Where (i) is the epoch number and (j) is east, north and height direction.• The RMSE (Root Mean Square Error) for the total
number of epochs (n).
• RMSE in 3 dimensions.
4th International Conference on Machine Control & Guidance, March 19-20, 2014
10
4. DATA ACQUSITION• Two kinematic
trajectories , Stuttgart, Germany with sampling interval of 1 second.
• Using the measurement van of the Institute.
• The observations started with 60 minutes static data as an initialization time.
• 30 minutes of kinematic measurements.
4th International Conference on Machine Control & Guidance, March 19-20, 2014
11
4.1 First data set
• A high number of satellites.• A little signal disturbance (cycle slips)
4th International Conference on Machine Control & Guidance, March 19-20, 2014
12
4.2 Second data set
• More signal disturbance (cycle slips)
4th International Conference on Machine Control & Guidance, March 19-20, 2014
13
5.1.1 First data using CSRS-PPP
• It provides RMSE in 3D of 11 cm with 10 minutes initialization times and reaches 5 cm in after 40 minutes.
• Height coordinates are the most varying parameter with different initialization time.
5. RESULTS AND ANALYSIS
4th International Conference on Machine Control & Guidance, March 19-20, 2014
14
5.1.2 First data using GIPSY-OASIS
• GIPSY provide a gradually improvement in accuracy level.
• RMSE in east and north significantly improved from 00 to 20 minutes initialization times.
• It provides RMSE in 3D of 7 cm with 20 minutes initialization times.
4th International Conference on Machine Control & Guidance, March 19-20, 2014
15
5.2.1 Second data using CSRS-PPP
• Horizontal direction: RMSE values from 3 to 12 cm.
• Height direction: RMSE values from 10 to 26 cm.• RMSE 3D: 10 cm with 60 minutes initialization
time. • The accuracy improved significantly from 20
minutes initialization time.
4th International Conference on Machine Control & Guidance, March 19-20, 2014
16
5.2.2 Second data using GIPSY-OASIS [Gradient model]
• With standard tropospheric formula: un reliable results.
• Some trails to model tropospheric correction; gradient model characterizes the horizontal dimension of the tropospheric delay.
• First stable solution: from 20 minutes initialization times .
• Horizontal solution: around 10 cm RMSE and height direction has the most varying parameter
4th International Conference on Machine Control & Guidance, March 19-20, 2014
17
5.2.2 Second data GIPSY-OASIS [Wet CSRS model]
• Wet parameters is high variable parameters and it should be predicted.
• Wet tropospheric values from CSRS-PPP online service.
• RMSE values for horizontal: 5 cm level from 10 minutes.
• RMSE 3D values : below 15 cm.
4th International Conference on Machine Control & Guidance, March 19-20, 2014
18
6. CONCLUSIONS• GIPSY-OASIS software and CSRS-PPP online
service were used to determine a PPP solution.• The assessment study aims to evaluate the
effect of the initialization times on kinematic positioning.
The first data set has a good data quality. • GIPSY-OASIS software: RMSE 3D of 7 cm from 20
minutes initialization time.
• CSRS-PPP online service: RMSE 3D of 11 cm for 10 minutes initialization time ; reaches 5 cm for 40 minutes initialization time.
4th International Conference on Machine Control & Guidance, March 19-20, 2014
19
6. CONCLUSIONSThe second data set has more signal disturbance
.• CSRS-PPP online service : RMSE for horizontal
directions from 3 to 12 cm ; for height direction from 10 to 26 cm.
• CSRS-PPP: a reliable solution from 20 minutes initialization times.
• GIPSY-OASIS : the standard tropospheric formula does not provide a suitable result.
• The gradient model : an improvement of PPP accuracy from 20 minutes initialization time.
• Wet parameters from CSRS-PPP : shows the best solution for this data set ; RMSE values in horizontal direction of 5 cm and 10 cm for height from 10 minutes initialization time.
4th International Conference on Machine Control & Guidance, March 19-20, 2014
20
Thank you for your Attention!
QUESTIONS Contact:• M.Sc. Ashraf Abdallah• Institute of Engineering Geodesy, University of Stuttgart
• Geschwister-Scholl Str. 24D, 70174 Stuttgart, Germany
• Phone: +49 (0711) 685-84051 • Fax : +49 (0711) 685-84044 • Email : Ashraf.Abdallah@ingeo.uni-stuttgart.de