Automated measurement of local ties and antenna parameters

Automated measurement of local ties and antenna parameters automated measurement of local ties and antenna parameters Proof-of-concept demonstration Benno Schmeing University of Bonn, IGG B. S. Schmeing 23 -September-2009

Automated measurement of local ties and antenna parameters Contents • Introduction – Motivation – Objectives • GGAO local site • Chosen Approach – – Design of the monitoring system Measurement procedure Mathematical model Analysis • Results – Calibration – Simulation – Measurement results B. S. Schmeing 23 -September-2009

Automated measurement of local ties and antenna parameters Motivation • for VLBI 2010 + GGOS 2020 • reduce working hours needed for determination of local ties • shorten monitoring interval here: proof-of-concept for VLBI antenna at GGAO B. S. Schmeing 23 -September-2009

Automated measurement of local ties and antenna parameters Motivation B. S. Schmeing 23 -September-2009

Automated measurement of local ties and antenna parameters Objectives • Monitoring of VLBI antenna‘s – Reference point – Axis offset – Orientation of azimuth and elevation axes • Requirements: – Accuracy < 1 mm – Automatic operations – Ability to include additional sensors, e. g. GPS, SLR B. S. Schmeing 23 -September-2009

Automated measurement of local ties and antenna parameters GGAO • 4 different geodetic sensors: – – GPS VLBI SLR DORIS • Geodetic network consisting of several piers and ground markers • We will concentrate on the VLBI antenna: B. S. Schmeing 23 -September-2009

Automated measurement of local ties and antenna parameters B. S. Schmeing 23 -September-2009

Automated measurement of local ties and antenna parameters Design of the monitoring system? • How to identify antenna dish movement? Ø 360° prism marks one discrete point of the dish Ø total station determines prism’s movement • How to embed antenna parameters into (local) reference frame, e. g. to get local ties? Ø coordinates of piers and ground markers define local reference frame Ø Additionally possible: GPS sensors set up on the points • How to control antenna movement? Ø connection to Field System computer Ø Field System puts movement commands into practice B. S. Schmeing 23 -September-2009

Automated measurement of local ties and antenna parameters Design of the monitoring system? • How to control station? Ø using implemented interface (Lemo-RS 232 interface with GSI commands) • How to achieve needed accuracy? Ø calibration of 360° prism’s orientation-dependent errors Ø correct atmospheric influence on total station measurements Ø eliminate instrument errors using the right measurement procedure B. S. Schmeing 23 -September-2009

Automated measurement of local ties and antenna parameters Design of the monitoring system • 360° prism mounted on antenna B. S. Schmeing 23 -September-2009

Automated measurement of local ties and antenna parameters Design of the monitoring system • Total station(s) on piers around the antenna B. S. Schmeing 23 -September-2009

Automated measurement of local ties and antenna parameters Design of the monitoring system • TCA specifications: (from: http: //leica. loyola. com/products/total-stations/images/tps 2000_lg. jpg; 09/14/2009) B. S. Schmeing 23 -September-2009

Automated measurement of local ties and antenna parameters Design of the monitoring system • TCA specifications: – angle measurement accuracy: 0. 15 mgon (due atmosphere influence etc reachable accuracy is somewhat lower) – distance measurement accuracy: 1 mm + 1 ppm – measurement distance (ATR): 5 … 500 m – measurement time: ~ 3 sec B. S. Schmeing 23 -September-2009

Automated measurement of local ties and antenna parameters Design of the monitoring system • Laptop as control unit for total station and antenna B. S. Schmeing 23 -September-2009

Automated measurement of local ties and antenna parameters Design of the monitoring system measures to antenna directions + distances marker positions, control commands controls antenna movement, measures weather antenna positions, weather information antenna control commands B. S. Schmeing 23 -September-2009

Automated measurement of local ties and antenna parameters Design of the monitoring system • Measurements controlled by Laptop (with Matlab) Ø Field System controls antenna movement and returns antenna position Ø Field System provides atmospheric conditions Ø Total station measures marker position • Data structure Ø Based on ASCII files Ø Files for … … network point coordinates and accuracy … calibration results … measurement schedules … measurement results B. S. Schmeing 23 -September-2009

Automated measurement of local ties and antenna parameters Design of the monitoring system Example: antenna measurement plan B. S. Schmeing 23 -September-2009

Automated measurement of local ties and antenna parameters Design of the monitoring system Example: network measurement plan B. S. Schmeing 23 -September-2009

Automated measurement of local ties and antenna parameters Measurement procedure 1) set up total station – leveling – determine approximate orientation + position 2) target prisms on other network points – ‘network measurement plans’ – provides data for exact determination of orientation (and position) 3) target prism on VLBI antenna at different azimuth and elevation positions – ‘antenna measurement plans’ – measuring the marker positions at different antenna azimuth and elevation positions B. S. Schmeing 23 -September-2009

Automated measurement of local ties and antenna parameters Measurement procedure • set up total station: – levelling – determine orientation and position B. S. Schmeing 23 -September-2009

Automated measurement of local ties and antenna parameters Measurement procedure • Set up total station: – levelling – determine orientation and position B. S. Schmeing 23 -September-2009

Automated measurement of local ties and antenna parameters Measurement procedure • Network measurements: – measure directions and distances to other network points – observations B. S. Schmeing 23 -September-2009

Automated measurement of local ties and antenna parameters Measurement procedure • Antenna measurements: – measure directions and distances to antenna in different positions – observations B. S. Schmeing 23 -September-2009

Automated measurement of local ties and antenna parameters Measurement procedure • Antenna measurements: – measure directions and distances to antenna in different positions – observations B. S. Schmeing 23 -September-2009

Automated measurement of local ties and antenna parameters Measurement procedure • Antenna measurements: – measure directions and distances to antenna in different positions – observations B. S. Schmeing 23 -September-2009

Automated measurement of local ties and antenna parameters Measurement procedure • Antenna measurements: – measure directions and distances to antenna in different positions – observations B. S. Schmeing 23 -September-2009

Automated measurement of local ties and antenna parameters Measurement procedure • Antenna measurements: – measure directions and distances to antenna in different positions – observations B. S. Schmeing 23 -September-2009

Automated measurement of local ties and antenna parameters Measurement procedure • Antenna measurements: – measure directions and distances to antenna in different positions – observations B. S. Schmeing 23 -September-2009

Automated measurement of local ties and antenna parameters Measurement procedure • Antenna measurements: – measure directions and distances to antenna in different positions – observations B. S. Schmeing 23 -September-2009

Automated measurement of local ties and antenna parameters Traditional approach • circle fitting: – separate antenna rotations around azimuth and elevation axis – estimation of circles described by antenna movement – reference point is projection from elevation axis onto azimuth axis B. S. Schmeing 23 -September-2009

Automated measurement of local ties and antenna parameters Traditional approach • circle fitting: (Johnston: The 2003 Yarragadee (Moblas 5) Local Tie Survey, GEOSCIENCE AUSTRALIA , RECORD 2004/19 ) B. S. Schmeing 23 -September-2009

Automated measurement of local ties and antenna parameters Mathematical model • new approach [Loesler 2008 a, Loesler 2008 b]: – set of rotations and translations – describing transformation from antenna-fixed into local coordinate system – transformation parameters describe antenna characteristics B. S. Schmeing 23 -September-2009

Automated measurement of local ties and antenna parameters Mathematical model B. S. Schmeing 23 -September-2009

Automated measurement of local ties and antenna parameters Mathematical model • • a, b … marker coordinates in telescope system E, OE… rotation around elevation axis (+orientation) ecc … axis offset (eccentricity) A, OA… rotation around Azimuth axis (+orientation) PR … antenna’s reference point a, b … correction for non-orthogonality of axes g … correction for inclination B. S. Schmeing 23 -September-2009

Automated measurement of local ties and antenna parameters Marker position (in telescope system): B. S. Schmeing 23 -September-2009

Automated measurement of local ties and antenna parameters Elevation rotation: B. S. Schmeing 23 -September-2009

Automated measurement of local ties and antenna parameters Axis offset (eccentricity): B. S. Schmeing 23 -September-2009

Automated measurement of local ties and antenna parameters Azimuth rotation: B. S. Schmeing 23 -September-2009

Automated measurement of local ties and antenna parameters Translation into local system: B. S. Schmeing 23 -September-2009

Automated measurement of local ties and antenna parameters Mathematical model Observations: – Marker positions : x, y, z (by total station) – Antenna positions : A, E (by Field System) Parameters: – “antenna” : PR, ecc, a, b, g, OA – “marker” : a, b, OE B. S. Schmeing 23 -September-2009

Automated measurement of local ties and antenna parameters Mathematical model Observations: – Marker positions : x, y, z (by total station) – Antenna positions : A, E (by Field System) Parameters: – “antenna” : PR, ecc, a, b, g, OA – “marker” : a, b, OE B. S. Schmeing 23 -September-2009

Automated measurement of local ties and antenna parameters Analysis • data record for local network observations: – – – position and target ID horizontal + vertical direction and distance to target instrument settings (distance corrections, serial no. ) time tag information about atmospheric conditions • data record for observations of VLBI antenna: – local network observables plus – antenna position (azimuth + elevation) B. S. Schmeing 23 -September-2009

Automated measurement of local ties and antenna parameters Analysis previous measurements network measurement Hz, V, Sd point coordinates + covariance matrix + weather data antenna measurement azimuth + elevation of antenna coordinate estimation using weak datum Hz, V, Sd antenna parameter estimation: loesler algorithm coordinates of the marker on the VLBI antenna in the local system antenna parameters B. S. Schmeing 23 -September-2009

Automated measurement of local ties and antenna parameters Analysis previous measurements network measurement Hz, V, Sd point coordinates + covariance matrix + weather data antenna measurement azimuth + elevation of antenna coordinate estimation using weak datum Hz, V, Sd antenna parameter estimation: loesler algorithm coordinates of the marker on the VLBI antenna in the local system antenna parameters B. S. Schmeing 23 -September-2009

Automated measurement of local ties and antenna parameters Analysis antenna measurement B. S. Schmeing 23 -September-2009

Automated measurement of local ties and antenna parameters Analysis antenna measurement Hz, V, Sd + weather data Separate coordinate estimation azimuth + elevation of antenna Separate antenna parameter estimation marker coordinates in current instrument reference frame Antenna parameters in different reference frames Comparison of reference frameindependent parameters B. S. Schmeing 23 -September-2009

Automated measurement of local ties and antenna parameters Calibration • TCA 2003: – additive constant • Field System: – measurement accuracy • prisms for network points: – additive constant • 360° prism used as marker – additive constant – orientation-dependent change of reference point B. S. Schmeing 23 -September-2009

Automated measurement of local ties and antenna parameters Calibration • TCA: – additive constant • Field System: – measurement accuracy (azimuth and elevation positions) • prisms for network points: – additive constants • 360° prism used as marker – additive constant – orientation-dependent change of reference point B. S. Schmeing 23 -September-2009

Automated measurement of local ties and antenna parameters Calibration • TCA: – additive constant • Field System: – measurement accuracy • prisms for network points: – additive constant • 360° prism used as marker – additive constant – orientation-dependent change of reference point B. S. Schmeing 23 -September-2009

Automated measurement of local ties and antenna parameters Calibration • TCA: – additive constant • Field System: – measurement accuracy • prisms for network points: – additive constant • 360° prism used as marker – additive constant – orientation-dependent change of reference point B. S. Schmeing 23 -September-2009

Automated measurement of local ties and antenna parameters Calibration B. S. Schmeing 23 -September-2009

Automated measurement of local ties and antenna parameters Simulation • Network simulation – done using PANDA (commercial geodetic analysis software by Geotec Gmb. H) – input: approximate network coordinates instrument’s accuracy (0. 45 mgon and 1 mm+1 ppm) planned measurement schedule (equivalent to carried out network measurement) – result: projected accuracy B. S. Schmeing 23 -September-2009

Automated measurement of local ties and antenna parameters Simulation • Formal errors from PANDA network simulation: Point ID Point name # measurements from to formal errors [mm] sx sy sz 1 Pier A 4 2 0. 23 0. 14 2 unnamed 0 3 0. 28 0. 24 0. 15 3 RM 1 5 3 0. 24 0. 21 0. 14 4 Pier C 4 3 0. 23 0. 14 5 JPL West 4 2 0. 20 0. 24 0. 12 6 Pier B 0 4 0. 25 0. 36 0. 25 • Centering accuracy: – forced centering on piers: – forced centering above ground markers: ~ 0. 1 mm ~ 1. 0 mm (x, y) ~ … cm (z) B. S. Schmeing 23 -September-2009

Automated measurement of local ties and antenna parameters Simulation • Accuracy of coordinates + instrument setup: Point ID Point name # measurements from to formal errors [mm] sx sy sz 1 Pier A 4 2 0. 23 0. 14 2 unnamed 0 3 0. 28 0. 24 0. 15 3 RM 1 5 3 1. 00 - 4 Pier C 4 3 0. 23 0. 14 5 JPL West 4 2 1. 00 - 6 Pier B 0 4 0. 25 0. 36 0. 25 B. S. Schmeing 23 -September-2009

Automated measurement of local ties and antenna parameters Simulation • Antenna simulation – done using Matlab – input: network coordinates + accuracy (from network simulation) measurement accuracy measurement schedules to simulate – result: true errors and formal errors from antenna parameter estimation for chosen settings B. S. Schmeing 23 -September-2009

Automated measurement of local ties and antenna parameters Simulation • Visualization of a single antenna measurement schedule B. S. Schmeing 23 -September-2009

Automated measurement of local ties and antenna parameters Simulation • Antenna measurement simulation settings: – – sangles : 0. 45 mgon sdistances : 1. 0 mm s. Field. System: 5. 0 mdeg smarker : 0. 5 mm • 2 simulations: – using just one instrument position (here: point 4) – using 4 instrument positions (points 1, 3, 4, 5) B. S. Schmeing 23 -September-2009

Automated measurement of local ties and antenna parameters Simulation • results (point 4): parameter True error Formal error ratio ref point (x) 0. 1489 mm 0. 1836 mm 0. 81 ref point (y) 0. 0797 mm 0. 1044 mm 0. 76 ref point (z) 0. 1387 mm 0. 1682 mm 0. 82 axis offset 0. 1295 mm 0. 1629 mm 0. 80 alfa 0. 0655 mrad 0. 0833 mrad 0. 79 beta 0. 0339 mrad 0. 0444 mrad 0. 76 gamma 0. 1775 mrad 0. 2283 mrad 0. 78 azi orientation 0. 1440 mrad 0. 1938 mrad 0. 74 a 0. 1084 mm 0. 1455 mm 0. 75 b 0. 4638 mm 0. 6035 mm 0. 77 ele orientation 0. 0485 mrad 0. 0591 mrad 0. 82 B. S. Schmeing 23 -September-2009

Automated measurement of local ties and antenna parameters Simulation • results (points 1, 3, 4, 5): parameter True error Formal error ratio ref point (x) 0. 0402 mm 0. 0533 mm 0. 73 ref point (y) 0. 0409 mm 0. 0525 mm 0. 79 ref point (z) 0. 0625 mm 0. 0797 mm 0. 78 axis offset 0. 0649 mm 0. 0764 mm 0. 85 alfa 0. 0205 mrad 0. 0248 mrad 0. 83 beta 0. 0189 mrad 0. 0232 mrad 0. 81 gamma 0. 0910 mrad 0. 1120 mrad 0. 81 azi orientation 0. 0789 mrad 0. 0936 mrad 0. 84 a 0. 0585 mm 0. 0683 mm 0. 86 b 0. 2533 mm 0. 2970 mm 0. 85 ele orientation 0. 0209 mrad 0. 0272 mrad 0. 77 B. S. Schmeing 23 -September-2009

Automated measurement of local ties and antenna parameters Measurement results • irregularities in results • reason not found yet: – many outliers at measurement? – systematical errors? – software problems? Ø just preliminary results: comparison of reference-frame independent antenna parameters: – axis offset/eccentricity – correction angles – marker position: a, b, elevation orientation B. S. Schmeing 23 -September-2009

Automated measurement of local ties and antenna parameters Measurement results • measurements from 4 points: – – point 1 3 4 5 (Pier A) (RM 1) (Pier C) (JPL West) • separate analysis of every instrument position • settings: – angle measurement accuracy: 0. 45 mgon – distance measurement accuracy: 1. 00 mm – Field System accuracy: 5. 00 mdeg B. S. Schmeing 23 -September-2009

Automated measurement of local ties and antenna parameters Measurement results • geometry of the measured marker positions: B. S. Schmeing 23 -September-2009

Automated measurement of local ties and antenna parameters Measurement results parameter Estimated values [m] & formal errors [mm] point 1 point 3 point 4 point 5 position (x) 5020. 9106 0. 12 5020. 9112 0. 25 5020. 9143 0. 24 5020. 9212 0. 20 position (y) 453. 6017 0. 39 453. 6029 0. 17 453. 6025 0. 12 453. 5946 0. 15 position (z) 17. 8674 0. 26 16. 5600 0. 20 17. 8704 0. 19 16. 5977 0. 19 1. 9 * 10 -3 0. 23 2. 0 * 10 -3 0. 18 1. 5 * 10 -3 0. 18 1. 2 * 10 -3 0. 18 axis offset … … … selected estimated parameters [m] … according formal errors [mm] B. S. Schmeing 23 -September-2009

Automated measurement of local ties and antenna parameters Measurement results parameter deviations from mean & formal errors point 1 point 3 Point 4 unit point 5 axis offset 0. 22 0. 25 0. 36 0. 20 -0. 14 0. 21 -0. 43 0. 20 mm alfa 0. 12 0. 07 0. 12 0. 08 -0. 23 0. 10 -0. 01 0. 09 m° beta -0. 41 0. 12 0. 33 0. 07 -0. 20 0. 06 0. 28 0. 08 m° 0. 18 0. 56 -0. 18 0. 45 -0. 07 0. 38 0. 07 0. 36 m° a -0. 21 0. 20 -0. 73 0. 16 0. 30 0. 17 0. 64 0. 17 mm b -0. 55 1. 41 0. 28 1. 15 0. 27 0. 98 -0. 01 0. 94 mm 0. 35 0. 08 0. 49 0. 06 -0. 21 0. 07 -0. 63 0. 07 m° gamma ele orientation B. S. Schmeing 23 -September-2009

Automated measurement of local ties and antenna parameters Measurement results • residuals: B. S. Schmeing 23 -September-2009

Automated measurement of local ties and antenna parameters Measurement results • normalized residuals: B. S. Schmeing 23 -September-2009

Automated measurement of local ties and antenna parameters Conclusions • automated measurement procedure works • easy operations / does not need expert surveyors • projected accuracy meets goals • some data anomalies need further investigation B. S. Schmeing 23 -September-2009

Automated measurement of local ties and antenna parameters Future Work • investigate data anomalies • use several total stations simultaneously – increased data collection rate – increased accuracy • replace 360° prism with target sphere – eliminates one possible source of error – no limitations on observing angle • apply the approach to SLR B. S. Schmeing 23 -September-2009

Automated measurement of local ties and antenna parameters Bibliography • Loesler 2008 a Loesler, M. and M. Hennes (May 2008): An innovative mathematical solution for a time-efficient IVS reference point determination In MEASURING THE CHANGES – 13 th FIG Symposium on Deformation Measurement and Analysis, 4 th IAG Symposium on Geodesy for Geotechnical and Structural Engineering Geodetic Institute of Karlsruhe (TH), Germany • Loesler 2008 b Loesler, M. (2008): Reference point determination with a new mathematical model at the 20 m VLBI telescope in Wettzell Journal of Applied Geodesy, pages 233 -238 B. S. Schmeing 23 -September-2009

Automated measurement of local ties and antenna parameters Acknowledgements • Honeywell Technical Solutions Inc. – supply of robotic total station TCA 2003 • NGS – calibration facility at Corbin • Jim Long, Jay Redmond, Mark Evangelista and Irv Diegel (Honeywell) – site and equipment support B. S. Schmeing 23 -September-2009

Automated measurement of local ties and antenna parameters The End Thank you for your attention. B. S. Schmeing 23 -September-2009