procedure for analyzing geometreical … edm calibration bench ghent university, department of...

FIG Working Week 2011

Bridging the Gap between Cultures

Marrakech, Morocco, 18‐22 May 2011 1

PROCEDURE FOR ANALYZING

GEOMETREICAL CHARACTERISTICS OF

AN EDM CALIBRATION BENCHGhent University, Department of Geography,

Ghent, Belgium

3D Data Acquisition Cluster

Alain De Wulf

Denis Constales

Jessica Meskens

Timothy Nuttens

Cornelis Stal

Overview• Calibration Bench

• Research topic & Error Sources

• Methodology

• Results

• Future Research

• Conclusion

2

- Overview

- Calibration Bench

- Research topic-Error Sources

- Methodology

- Beam alignment

- Software settings

- Addition Constant

- Principles of

Measurement

- Computations

- Results- Vertical Offset

- Lateral Offset

- Roll

- Pitch

- Future

- Conclusion




Calibration Bench (UGent)– ca. 20 m length, 1 m high, 3 dm large

– Reinforced concrete beam on wall brick filled

with sand. Total weight: approx. 105 kN.

3

- Overview

- Calibration Bench


- Methodology

- Beam alignment

- Software settings

- Addition Constant

- Principles of

Measurement

- Computations


- Lateral Offset

- Roll

- Pitch

- Future

- Conclusion

Calibration Bench (UGent)– Lasertex LSP-30 interferometer (HeNe 633 nm)

– Range: 30 m

– Resolution: 0.001 or 0.01 mm (software setting)

– Accuracy: 0.001 mm + 1,5 ppm (<> typical 2 mm

+ 2 ppm for a total station, e.g. Trimble S6)

– Reinforced concrete beam on wall brick filled

with sand. Total weight: approx. 105 kN.

4

- Overview

- Calibration Bench


- Methodology

- Beam alignment

- Software settings

- Addition Constant

- Principles of

Measurement

- Computations


- Lateral Offset

- Roll

- Pitch

- Future

- Conclusion




Calibration Bench (UGent)– Carrier with double

prism

– On aluminium rail

– Allows simultaneous

distance measurements

to both interferometer

and total station

5

- Overview

- Calibration Bench


- Methodology

- Beam alignment

- Software settings

- Addition Constant

- Principles of

Measurement

- Computations


- Lateral Offset

- Roll

- Pitch

- Future

- Conclusion

Calibration Bench (UGent)– Manual movement

– Four lateral gliding wheels

making contact with tubular

steel tubes (10 mm diameter, 6

m length per section)

6

- Overview

- Calibration Bench


- Methodology

- Beam alignment

- Software settings

- Addition Constant

- Principles of

Measurement

- Computations


- Lateral Offset

- Roll

- Pitch

- Future

- Conclusion

sleufgat 9mm op 16mm




7

- Overview

- Calibration Bench


- Methodology

- Beam alignment

- Software settings

- Addition Constant

- Principles of

Measurement

- Computations


- Lateral Offset

- Roll

- Pitch

- Future

- Conclusion

Research topic

8

• Quantify the alignment errors of the moving carrier

on the rail

– Vertical and lateral offsets

– Rotations (pitch, roll, yaw)

• Gather information to allow a well founded decision:

either to physically adjust the rail or to compute and

apply an error correction model.

- Overview

- Calibration Bench

- Research topic

-Error Sources

- Methodology

- Beam alignment

- Software settings

- Addition Constant

- Principles of

Measurement

- Computations


- Lateral Offset

- Roll

- Pitch

- Future

- Conclusion




Additional error sources

9

• Influence of atmospheric conditions: temperature,

air pressure and humidity

– High accuracy atmospheric measurements

with sensors attached to the rail

– Lower accuracy atmospheric measurements in

the lab with Weather station Nexus Pro 2009

• Dead path error

• Cosine error

• Abbe error

• Instability of the laserbeam

• …

- Overview

- Calibration Bench


- Methodology

- Beam alignment

- Software settings

- Addition Constant

- Principles of

Measurement

- Computations


- Lateral Offset

- Roll

- Pitch

- Future

- Conclusion

Laser Beam Alignment• Minimum 80 % reflection strength of the laser

beam signal needed in every point of the bench

• Fixed and moving interferometer prisms should

be aligned with the laser beam

10

- Overview

- Calibration Bench


- Methodology

- Beam alignment

- Software settings

- Addition Constant

- Principles of

Measurement

- Computations


- Lateral Offset

- Roll

- Pitch

- Future

- Conclusion




Software Settings

11

- Overview

- Calibration Bench


- Methodology

- Beam alignment

- Software settings

- Addition Constant

- Principles of

Measurement

- Computations


- Lateral Offset

- Roll

- Pitch

- Future

- Conclusion

Principles of Measurement• Carrier has two targets at

the left and right bottom

sides of the carrier

• Zenithal (= vertical) and

horizontal angle

measurements are

performed to both targets

and also to the total station

prism in the middle

• EDM to the prism is also

performed

12

- Overview

- Calibration Bench


- Methodology

- Beam alignment

- Software settings

- Addition Constant

- Principles of

Measurement

- Computations


- Lateral Offset

- Roll

- Pitch

- Future

- Conclusionv

v




Principles of Measurement

• Carrier is placed at the “end” (= near to the

interferometer)

• The height of the totalstation (Trimble S6) is

adapted so that the zenithal angle = 100 grades

(horizontal line-of –sight)

• The Horizontal angle is set to zero

13

Start

End

- Overview

- Calibration Bench


- Methodology

- Beam alignment

- Software settings

- Addition Constant

- Principles of

Measurement

- Computations


- Lateral Offset

- Roll

- Pitch

- Future

- Conclusion


– Measure every 15 cm

– Record the laserinterferometer distance

– Measure the vertical and horizontal angle to both targets and the prism and also measure the distance to the prism

14

- Overview

- Calibration Bench


- Methodology

- Beam alignment

- Software settings

- Addition Constant

- Principles of

Measurement

- Computations


- Lateral Offset

- Roll

- Pitch

- Future

- Conclusion




1. Distance error (= difference between

interferometer and total station)

2. Vertical offset 3. Lateral offset

15

- Overview

- Calibration Bench


- Methodology

- Beam alignment

- Software settings

- Addition Constant

- Principles of

Measurement

- Computations


- Lateral Offset

- Roll

- Pitch

- Future

- Conclusion


Computations

16

- Overview

- Calibration Bench


- Methodology

- Beam alignment

- Software settings

- Addition Constant

- Principles of

Measurement

- Computations


- Lateral Offset

- Roll

- Pitch

- Future

- Conclusion




17

- Overview

- Calibration Bench


- Methodology

- Beam alignment

- Software settings

- Addition Constant

- Principles of

Measurement

- Computations

- Results

- Vertical Offset

- Lateral Offset

- Roll

- Pitch

- Future

- Conclusion

-4

-3,5

-3

-2,5

-2

-1,5

-1

-0,5

0

0,5

1

0 5000 10000 15000 20000

εHA prism(mm)

Distance

(mm)

Summary of εHA prism

εHAprisma,reëel D1 (F21a) εHAprisma,reëel D2 (F21a) εHAprisma,reëel D3 (F21a) εHAprisma,reëel gem (F21a)

Distance Error

18

- Overview

- Calibration Bench


- Methodology

- Beam alignment

- Software settings

- Addition Constant

- Principles of

Measurement

- Computations


- Lateral Offset

- Roll

- Pitch

- Future

- Conclusion -4,50

-4,00

-3,50

-3,00

-2,50

-2,00

-1,50

-1,00

-0,50

0,00

0,50

0 5000 10000 15000 20000

∆VD (mm)

Distance

(mm)

ΔVAprisma (mm) ΔVAst.links (mm) ΔVAst.rechts (mm)

∆VD

Vertical offset




19

- Overview

- Calibration Bench


- Methodology

- Beam alignment

- Software settings

- Addition Constant

- Principles of

Measurement

- Computations


- Lateral Offset

- Roll

- Pitch

- Future

- Conclusion0

5000

10000

15000

20000

-3 -2,5 -2 -1,5 -1 -0,5 0 0,5 1

∆LD (mm)

Distance

(mm)

∆LD

ΔZAprism ΔZAst.l. ΔZAst.r.

Lateral offset

Rotations

• Roll-, pitch- en yaw-rotations

20

Towards

totaalstation

Towards

laserinterferometer

- Overview

- Calibration Bench


- Methodology

- Beam alignment

- Software settings

- Addition Constant

- Principles of

Measurement

- Computations


- Lateral Offset

- Roll

- Pitch

- Future

- Conclusion




Roll

Computed out of left/right

difference of vertical offsets

21

- Overview

- Calibration Bench


- Methodology

- Beam alignment

- Software settings

- Addition Constant

- Principles of

Measurement

- Computations


- Lateral Offset

- Roll

- Pitch

- Future

- Conclusion

-4,50

-4,00

-3,50

-3,00

-2,50

-2,00

-1,50

-1,00

-0,50

0,00

0,50

0 5000 10000 15000 20000

∆VD

(mm)

Distance

(mm)ΔVAprisma (mm)

ΔVAst.links (mm)

∆VD

22

- Overview

- Calibration Bench


- Methodology

- Beam alignment

- Software settings

- Addition Constant

- Principles of

Measurement

- Computations


- Lateral Offset

- Roll

- Pitch

- Future

- Conclusion

-4,50

-4,00

-3,50

-3,00

-2,50

-2,00

-1,50

-1,00

-0,50

0,00

0,50

0 5000 10000 15000 20000

∆VD

(mm)

Distance

(mm)ΔVAprisma (mm)

ΔVAst.links (mm)

∆VD

Pitch

Computed out of differences of vertical offsets in subsequent points




Future

• Fixed reference point, independent from bench

construction, for zero-settings

• Interferometric measurement of roll and pitch

• Decision about adjusting the rail or modelling the

offsets is still to take

23

- Overview

- Calibration Bench


- Methodology

- Beam alignment

- Software settings

- Addition Constant

- Principles of

Measurement

- Computations


- Lateral Offset

- Roll

- Pitch

- Future

- Conclusion

Conclusion

• A methodology was suggested for the

computation of horizontal and vertical offsets of

an EDM calibration bench.

• The repeatability (approximation of the random

error) of this methodology is in the order of 0.2-

0.3 mm.

• With interferometry we hope to be able to

measure with accuracies better than 0.1 mm.

24

- Overview

- Calibration Bench


- Methodology

- Beam alignment

- Software settings

- Addition Constant

- Principles of

Measurement

- Computations


- Lateral Offset

- Roll

- Pitch

- Future

- Conclusion




Questions?

25

Thank you for your attention !- Overview

- Calibration Bench


- Methodology

- Beam alignment

- Software settings

- Addition Constant

- Principles of

Measurement

- Computations


- Lateral Offset

- Roll

- Pitch

- Future

- Conclusion

Contact & Information:

[email protected]

Ghent University, Department of Geography,

Ghent (Belgium)

3D Data Acquisition Cluster

procedure for analyzing geometreical … edm calibration bench ghent university, department of...

Documents