1

ACCURATE ORIENTATION OF THE

GYROSCOPE’S CALIBRATION SYSTEM

NATIONAL TECHNICAL UNIVERSITY OF ATHENSNATIONAL TECHNICAL UNIVERSITY OF ATHENSSCHOOL OF RURAL AND SURVEYING ENGINEERINGSCHOOL OF RURAL AND SURVEYING ENGINEERING

DEPARTMENT OF TOPOGRAPHY DEPARTMENT OF TOPOGRAPHY

LABORATORY OF GENERAL GEODESYLABORATORY OF GENERAL GEODESY

Ε. Lambrou, G. Pantazis

FIG Working Week Athens, GreeceMay 22–27 2004

HELLENIC ASSOCIATION OF RURAL & SURVEYING ENGINEERS

TECHNICAL CHAMBER OF GREECE

Used for:GYROTHEODOLITE

� The initial orientation of the 3D – geodetic networks

� Determines the astronomical azimuth with high accuracy forcommon geodetic field works

� Underground surveying works in caves and mines.

�Orientation of airport radar or satellite antennas.

Advantages

� Ship navigation

� Orientation of army systems

� Its operation is independent from the sight and light conditions.

� The build-in gyroscope attachment doesn’t prevent other measurements by the theodolite.

� Check and calibration by using a collimator

CALLIBRATION

ooSSC b 360180 −++Α=Α Ο

� The astronomical azimuth of the collimator’s line

of sight must be determined

Astronomical azimuth may be determined Astronomical azimuth may be determined by the following methods:by the following methods:

DETERMINATION OF THE ASTRONOMICAL AZIMUTH

1. by equal altitudes of a star

2. by observing a circumpolar star near elongation

3. Ex-meridian observations to stars or the Sun, in which altitudes are measured

4. Observing a close circumpolar star at any hour angle

By determining the direction of the meridian of the station point

By measuring the angle between the vertical circle of the station point and the vertical circle of a celestial body

The systemThe system

S T A T IO NT O T A L

R S 2 3 2

P P S O U T P U T

G P S R E C E IV E RA N T E N N A G P S

B A T T E R Y

Measured

Horizontal angles UTC Time±1cc ±1msec

ERROR ANALYSIS (1)- The internal uncertainty is, about ±0″.3� Sighting error� The hour angle method error

- The external uncertainty � The error from the celestial coordinates (α, δ) of Polaris � The error from the estimate value of the

astronomical latitude

0,0

0,2

0,4

0,6

0,8

1,0

0 20 40 60 80

Astronomical Latitude Φ ( o )

σΑΦ

(ar

cse

con

ds

)

25''

20''15''10''5''

30''

δΦ

2

ERROR ANALYSIS (2)� The The error from the use error from the use of of an estimate value an estimate value ofof

astronomical longitudeastronomical longitude

� Errors Errors of of the total station right position the total station right position

� The The uncertainty uncertainty of of the sigthing the sigthing of of the initial direction the initial direction

� The The error in the measurement error in the measurement of of the horizontal angle bthe horizontal angle b

00.00050.001

0.00150.002

0.00250.003

0.00350.004

0.00450.005

0 20 40 60 80

Astronomical Latitude Φ ( o )

σΑΛ

(ar

cse

con

ds

)

20''

15''

10''

5''

30''

25''δΛ

Total determination error ≈1″.5

APPLICATION

Laboratory

Special accessories

APPLICATION

- The UTC time - The geodetic coordinates φ, λ.

-The celestial coordinatesα, δ of Polaris.

The horizontal angle ai

coshsintancos

sinharctan

⋅Φ−⋅Φ−=ΑδP

AAB

ai

+

CONCLUSIONS

� The determination of the astronomical azimuth of a collimator’s axis or any other arbitrary direction may be done by an accuracy of about ±1″by using the above described system, the total station and the GPS receiver, by the hour angle method and by sightings to Polaris.

� Special attention is needed to the marking of any points, which determine the directions, and also attention is needed to the measurement of the corresponding angles.

� The total duration of the application of the above methodology is about 1 hour.

� This methodology appears as convenient, fast, accurate and low cost, as the accurate periodical check of the gyroscope thodolite is necessary.

NATIONAL TECHNICAL UNIVERSITY OF ATHENSNATIONAL TECHNICAL UNIVERSITY OF ATHENSSCHOOL OF RURAL AND SURVEYING ENGINEERINGSCHOOL OF RURAL AND SURVEYING ENGINEERING

DEPARTMENT OF TOPOGRAPHY DEPARTMENT OF TOPOGRAPHY

LABORATORY OF GENERAL GEODESYLABORATORY OF GENERAL GEODESY

Ε. Lambrou, G. Pantazis

FIG Working Week Athens, GreeceMay 22–27 2004

HELLENIC ASSOCIATION OF RURAL & SURVEYING ENGINEERS

TECHNICAL CHAMBER OF GREECE

ACCURATE ORIENTATION OF THE

GYROSCOPE’S CALIBRATION SYSTEM