The GNSS Active Control Point Concept Get the {dynamic} Reference Points when You Need

Transcription

1 The GNSS Active Control Point Concept Get the {dynamic} Reference Points when You Need Joel van Cranenbroeck Chair of Commission 6 WG 6.2 International Federation of Surveyors (FIG) Belgium, Europa

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5 Total Station and Set-up on the Building Top 5

6 How to Setup the Total Station? Where are the control points? A Control Points GPS signals available XYZ 6

7 X t Y t Z t X t = X + Tilt X Y t = Y + Tilt Y 7

8 Kinematic Control 2 Point Concept (KC2PC) X t Y t Z t X t Y t Z t Automatique Total Station X t Y t Z t x o y o z o Kinematic Control 2 Point 1. The TPS measures on the prism/inclinometer - compensator OFF 2. Then measures the other points on the formwork. 3. The tilts are computed and applied on existing X,Y. 4. A 8 7 parameters transformation is applied on the other points. New 3D Point X t = X + Tilt X Y t = Y + Tilt Y

9 How to Setup the Total Station? Where are the control points? XYZ B XYZ NO Control Points GPS signals available 9

10 Active GPS Based Control Point Concept X t Y t Z t X t Y t Z t Automatique Total Station X t Y t Z t x o y o z o GPS Active Control Point 1. The TPS measures on the prism/gps - compensator OFF 2. Then measures the other points on the formwork. 3. The GPS fixes are computed and used as «known points». 4. A 7 parameters transformation is 1 applied on the other points. X New 3D Point, Y, Z, rot, rot Station Station Station X Y, Azimuth

11 11 GPS Continuous Operating Reference Station

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14 ACTIVE CONTROL POINTS TPS CONTINUOUS OPERATING REFERENCE STATION XY Coordinates and Orientation 14

15 Active GNSS Control Points Post-Processing or Real Time? yes Do we need to to obtain TPS coordinates Immediately on the building s top? no The surveyor will need to obtain the coordinates provided by GPS immediately on the TPS side The surveyor will need to obtain the coordinates provided by GPS in his office The Active Control Points must operate in Real time mode Wireless Communication GMX92 GG A GNSS Constinuously Operated Reference Station Leica GMX92 GG is mandatory in both case and must be located closed to the construction side ( less than 1 km ideally ) The Active Control Points can operate in Post-Processing mode Logging files on MC* GRX12 Pro GG 15 * MC = Memory Card

16 Active GNSS Control Points GNSS Monitoring Stations POST PROCESSING XYZ MCF256 Compact Flash card 256 MB READER In the Survey Office the PC running Leica GNSS Spider will log the observations of the CORS station continuously (RINEX). When the MC content will be downloaded on the PC, Leica LGO will be used to post-process the data and obtain the coordinates XYZ that will be used to set-up the coordinates of the TPS by free resection. 16

17 GNSS measurements are processed in «Mixed Tracks» mode using Leica LGO 17

18 Active GNSS Control Points GNSS Monitoring Stations Real-Time xyz xyz xyz xyz XYZ On the top of the buiding where the surveyor is setting up his Total Station, a Laptop PC running Leica GNSS Spider Positioning will be used to gather the data streams from every GNSS receiver in real time and will display the coordinates on the screen with information about the accuracy, availability and reliability. 18

19 Active Control Point in Real Time Mode 19

20 Depending of the environment (vibrations) and the application (moving platform) Steady Environment Vibrations 3D Space no gravity COMPENSATOR is ON CALCULATOR is ON One FACE measurements COMPENSATOR is OFF CALCULATOR is ON One FACE measurements COMPENSATOR is OFF CALCULATOR is OFF Two FACE measurements 2

21 3D transformation By using the measurement and the approximate (or setup with local axis) coordinates of the station and an approximate Hz orientation (or any direction) we are computing the local coordinate of all the control points. Then we basically have to compute a 3D transformation from the local coordinates into the control points reference system. 3 translations along X, Y and Z axis 3 rotations along the X,Y and Z axis 1 scale factor 21

22 = φ ω κ φ ω κ ω κ φ ω κ ω φ ω κ φ ω κ ω κ φ ω κ ω φ κ φ κ φ cos cos sin sin cos cos sin cos sin cos sin sin cos sin sin sin sin cos cos cos sin sin sin cos sin sin cos cos cos R ( ) + = = + = ds d d d ds d d d ds I ds 1 d d d ds 1 d d d ds 1 dr ds 1 R s ω φ ω κ φ κ ω φ ω κ φ κ ( ) X dr ds 1 dx X + + = = z y x i i i i i i i i i i i i dt dt dt d d d ds 1 x y z 1 x z y 1 y z x Z Y X κ φ ω

23 23 = z y x k k k k k k k k k j j j j j j j j j i i i i i i i i i k k k j j j i i i dt dt dt d d d ds 1 x y z 1 x z y 1 y z x 1 x y z 1 x z y 1 y z x 1 x y z 1 x z y 1 y z x Z Y X Z Y X Z Y X κ φ ω For 3 common points the following equations are solved using Least Squares Adjustment

24 [HONG KONG FREE STATION MEASUREMENTS] STNC, , , BS2-1, , , BS1-a, , , BS1-b, , , BS2-4, , , BS2-5, , , BS2-6, , , BS2-7, , , BS2-8, , , BS5, , , [HONG KONG CONTROL POINTS] BS2-1, , , 8.568,7 BS1-a, , , ,7 BS1-b, , , 12.36,7 BS2-4, , , ,7 BS2-5, , , ,7 BS2-6, , , ,7 BS2-7, , , ,7 BS2-8, , , 8.678,7 BS5, , , ,7 24

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27 Corrections on Control Points : Id. Vx(m) Vy(m) Vz(m) BS BS1-a BS1-b BS BS BS BS BS BS Tx updated : Ty updated : Tz updated :.91 Scale Factor updated : :7:12.96 Results of free station calculation (Reduced). Solution:ROBUST [GON/M] :7: Station Coordinates: , , :7: Standard Deviations:.6,.5, :7: Orientation:.1264,.285" :7: Scale: ,.735 Updated Rotation Matrix Rotations parameters Rotation along X axis :.31 Rotation along Y axis :.31 Rotation along Z axis : STNC X Y Z LEICA D Differences Point Identification n STNC X(2) = Y(2) = Z(2) = 5.281

28 Proof of Concept October 25 TPS12 GPS 1 GPS 2 GPS 3 Check Point 28

29 Results Tilted! SETUP Absolute Differences Relative Differences X Y Z x y z S S S S S S Tx updated : Ty updated : Tz updated : Scale Factor updated : Updated Rotation Matrix Rotations parameters Rotation along X axis : Rotation along Y axis :.497 Rotation along Z axis : Tx updated : Ty updated : Tz updated : Scale Factor updated : Updated Rotation Matrix Rotations parameters Rotation along X axis : Rotation along Y axis : Rotation along Z axis :

30 Considerations The way to design a solution is to first try to derive the calculations needed to provide the results. What can be computed by using the observables to derive the coordinates, can be computed by using directly the coordinates derived from the observations ( Joel s Principle ) and by considering the associated variance-covariance matrices. To provide «extreme» results we have to revisit the way we are calculating our coordinates Functional models developed for Photogrammetric applications have always been a source of inspiration. Active Control Point Concept can be extended to a network. GNSS Network corrections has demonstrated successful capacity to support monitoring operations. Much closed integration between GNSS measurements and TPS into a global computing scheme (mutual benefit) 3

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32 Building B, C and D TPS Monitoring 32

33 33 Niayesh Sadr Tunnel project

34 Networked Total Stations Concept (patented) Automatic Total Stations are networked using common points (pass points) that must be only considered as stable during the measurement cycles. GPS antenna s collocated with 36 degree reflectors are providing control points on the spot. 34

35 4 Hydro Power Stations World Bank Project UHE Ukraine 35

36 WORKFLOW Post-Processing TPS GNSS Base GNSS Control Hz, Vz, Ds Data Reduction T, ppm X, Y, Z Least Squares Adjust. Reporting, Archiving Minimum Constraints Quality Analysis Visualisation Data Snooping, Filtering Deformation Analysis Epoch of Reference? Yes Store Epoch of Reference No Statistical Analysis S-Transformation 36

37 High Rise Buildings Monitoring & GNSS Obstructions will remain a serious limitation on the use of GNSS Technology. But even for setting up GNSS Reference Stations to assist GNSS monitoring 38

38 Range Error ε Distance Dependency transmitted corrections ε R δ M ε M ε R Quality Degradation with Distance true corrections Reference Rover Distance Practical Limit of RTK 39

39 GNSS N-RTK : Derived Observation Corrections α Phase and Code Corrections δ δ ( N ( ϕ ϕ ) + E ( λ λ ) cos( ϕ )) r = R H ( N ( ϕ ϕ ) + E ( λ λ ) cos( ϕ )) r1 = β 1 R 1 R R R R Longitude and Latitude of the Rover ( x,y ) R k = R δ r Residuals are used to derive an interpolation model Typically ~ 8 km 4

40 Master Station(s) in N-RTK MAC transmitted corrections Range Error ε R δ M Quality Degradation from Interpolation true corrections ε R Reference Rover Reference Distance 41 With a GNSS Network RTK (interpolation & extrapolation) no more distance dependency. The choice of the Master Station can be any Reference station selected within the cell.

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44 GNSS Network RTK aided Seawall Monitoring System Diagram Lands Dept SatRef GPS Network Data AX122 GG antenna Check Point A Lightning rod and surge counter to grounding AX122 GG antenna Check Point B Lightning rod and surge counter to grounding Lands Dept SatRef GPS Network Data Modem cables GMX92 GG receiver DC batteries GMX92 GG receiver DC batteries Lands Dept SatRef GPS Network output 6 reference stations data streams via NTRIP to Control Center GPRS modems with fixed IP Modem cables GPRS modems with fixed IP Leica GNSS SpiderNET software process the sub network of Reference Stations provided by the Lands Dept SatRef GPS and derives the MAX corrections for a Master Station. TCP/IP transfer GPS raw data stream TCP/IP transfer GPS raw data stream Leica GNSS Spider Software computes coordinates of Check Point A and B by using the Master Station. Lands Dept SatRef GPS Network Data 45 GNSS QC software can be operated in the computer for data presentation & alarming Control Center with fixed IP Internet Connection

45 Single GPS RTK vs GPS Network RTK MAX Processing in Real Time L1 & L2 GPS data 46

46 Single GPS RTK vs GPS Network RTK MAX Processing in Real Time L1 & L2 GPS data 47

47 Single GPS RTK vs GPS Network RTK MAX Processing in Real Time L1 & L2 GPS data 48

48 Single GPS RTK vs GPS Network RTK MAX Processing in Real Time L1 only GPS data 49

49 Single GPS RTK vs GPS Network RTK MAX Processing in Real Time L1 only GPS data 5

50 Single GPS RTK vs GPS Network RTK MAX Processing in Real Time L1 only GPS data 51

51 High Rise Buildings Monitoring Using Virtual RS 52

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