GYROTHEODOLITE
NATIONAL TECHNICAL UNIVERSITY OF ATHENS
SCHOOL OF RURAL AND SURVEYING ENGINEERING
DEPARTMENT OF TOPOGRAPHY
LABORATORY OF GENERAL GEODESY
Used for:
The initial orientation of the 3D – geodetic networks
Underground surveying works in caves and mines.
Orientation of airport radar or satellite antennas.
Ship navigation
Orientation of army systems
ACCURATE ORIENTATION OF THE
GYROSCOPE’S CALIBRATION SYSTEM
Ε. Lambrou, G. Pantazis
TECHNICAL CHAMBER
OF GREECE
HELL ENIC ASSOCIATION OF RURAL &
SURVEYING ENGINEERS
FIG Working Week Athens, Greece
May 22–27
2004
CALLIBRATION
Check and calibration by using a collimator
The astronomical azimuth of the collimator’s line
of sight must be determined
Α SC = ΑΟS + b + 180 − 360
o
Advantages
Determines the astronomical azimuth with high accuracy for
common geodetic field works
Its operation is independent from the sight and light conditions.
The build-in gyroscope attachment doesn’t prevent other
measurements by the theodolite.
DETERMINATION OF THE
ASTRONOMICAL AZIMUTH
Astronomical azimuth may be determined
by the following methods:
By determining the direction of the meridian of the station
point
1. by equal altitudes of a star
2. by observing a circumpolar star near elongation
By measuring the angle between the vertical circle of the
station point and the vertical circle of a celestial body
o
3. Ex-meridian observations to stars or the Sun, in which
altitudes are measured
4. Observing a close circumpolar star at any hour angle
ERROR ANALYSIS (1)
The system
AN TEN NA G P S
G P S R E C E IV E R
T O TA L
S T A T IO N
P PS O UTPUT
RS 232
(arcseconds)
B ATTER Y
Measured
Horizontal angles
±1cc
- 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
UTC Time
±1msec
1,0
0,8
30''
25''
δΦ
0,6
20''
15''
10''
5''
0,4
Φ0,2
σΑ 0,0
0
20
40
Astronomical Latitude
Φ(
60
o
80
)
1
ERROR ANALYSIS (2)
APPLICATION
The error from the use of an estimate value of
astronomical longitude
0.005
0.0045
0.004
0.0035
0.003
0.0025
0.002
0.0015
Λ
Α 0.001
σ
0.0005
0
Special accessories
30''
(ar cs econds)
δΛ
25''
20''
15''
10''
5''
0
20
40
60
As tronomical Latitude
80
Φ ( o)
Errors of the total station right position
The uncertainty of the sigthing of the initial direction
The error in the measurement of the horizontal angle b
Total determination error ≈1″.5
APPLICATION
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.
- The UTC time
- The geodetic coordinates
φ, λ.
-The celestial coordinates
α, δ of Polaris.
ΑP
Laboratory
ai
− sinh
= arctan
cos Φ ⋅ tan δ − sin Φ ⋅ cosh
+
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.
The horizontal angle ai
This methodology appears as convenient, fast, accurate and low cost,
as the accurate periodical check of the gyroscope thodolite is necessary.
AAB
NATIONAL TECHNICAL UNIVERSITY OF ATHENS
SCHOOL OF RURAL AND SURVEYING ENGINEERING
DEPARTMENT OF TOPOGRAPHY
LABORATORY OF GENERAL GEODESY
ACCURATE ORIENTATION OF THE
GYROSCOPE’S CALIBRATION SYSTEM
TECHNICAL CHAMBER
OF GREECE
Ε. Lambrou, G. Pantazis
HELL ENIC ASSOCIATION OF RURAL &
SURVEYING ENGINEERS
FIG Working Week Athens, Greece
May 22–27
2004
2