Gyro Theodolite

Report
AMSZ AGM 2014
THE GYRO THEODOLITE
A brief look into Gyro- Theodolite technology and
its application
NYANGA
29 AUGUST 2014
TENDAI O. CHENGU
MINE SURVEYOR ( UNKI MINES)
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IMPORTANT!
History
• The gyro with 2 degrees of freedom
points north was discovered by a
French physicist Leon Foucault in 1750.
• The principle was adapted by Max
Schuler in 1921 to build the first
surveying gyro.
• In 1953 the gyro-theodolite which by
then was referred to as a meridian
pointer was first used by the Clausthal
mining academy underground.Weight
was 400kK and took about 3hrs current
technology at about 13.5 kg.
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Principle of operation
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Principle of operation
• A weight in form of pendulum attached to the
gyro axis will point to the center of the earth
and render spin axis horizontal (assuming the
axis is E-W).
• At B, the earth rotation causes the axis to show
an apparent tilt. The pendulum weight is no
longer evenly supported so that the effect of
gravity is felt mainly by the upper end of the
axis. The effect of this downward force is to
cause precession as shown at C .
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Principle of operation
• The added precession has the spin axis into
the N-S meridian. In this position the direction
of the rotor is the same as the earths so has no
effect the pendulum weight. Thus theoretically
the spin axis will point N-S and all movement
ceases.
• In practice however the inertia of the system
causes the spin axis to overshoot the N-S
meridian which results in oscillation of the
spin axis about the meridian.
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PURPOSE
Principle of operation
• Location of true north, therefore involves fixing the axis of
symmetry of the gyro oscillation about true north but since its
time wasting and uneconomical to allow the spin axis to steady in
the direction of true north various methods have been devised to
compute necessary direction from observation of simple
harmonic motion
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GYROMAT5000
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GYROMAX AK-2M
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GAK Cut-Away Drawing
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INTERNAL CONSTRUCTION
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SURVEY
Application or uses
•
•
•
•
•
•
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Azimuth checks on long traverses
Alignment of tunnels, railways and canals
Two point resection
Transfer of bearing into underground
Measurement of anomalies in geo-magnetic surveys
Military
Survey re-establishment with one peg present.
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Poor Surveying costs Production
• 10% production lost but we saved the
cost of a gyro !
• Saving money on surveying is a high
stakes gamble which, if lost, will make you
very infamous
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Misalignment errors
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costs
•
Gyromax Gyro with a Leica TS06 3” Instrument : R780 000DMT
•
GYROMAT5000 with Leica Total station is about R3,5 Million
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SAFETY CONSIDERATIONS
• Procurement procedures – national security
checks required. Approved user!
• Away from moving machinery. Cannot be
stopped when running.
• Atmospheric (winds, rain, sun)
• Environment – ground stability, power
cables and terrain hazards.
• Animal life –donkeys, ticks, dogs, snakes
• Equipment not intrinsically safe for fiery
mines. You might need GDI equipment.
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PURPOSE
Initial survey requirements:
a)Gyro Calibration base.
•
Must be robust
•
Must be linked to U/G Survey
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Secured, close to mine, wind shields.
b)
Software
c)
Meridian convergence tables
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CHECKING UNDERGROUND LINE
• The position of the baseline must be carefully
selected
• Secure pegs – i.e. away from tipping points and
roadways
• Ideally at every 500m
• Both points must be accessible
• Away from disturbances such as tramming as gyro
cannot be moved while running!!!
• Points must at least be 50m apart
• Away from electrical cables or transformers
• Avoid windy conditions fans and ventilation columns
• Gyro not fire proof .Conduct survey in non-fiery
areas of the mine .
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PROCEDURE OF CHECKING UNDERGROUND
LINE
• Calibrate the instrument on surface
• Set up instrument on one side of the baseline.
underground
• Ensure instrument is levelled and centered
• Orient the instrument to the termination point
• Observe both circle left and right
• Point instrument to position ± 50 from North i.e. East
then take same observations .Clamp the Gyro
• Point instrument to position ± 50 from North i.e.
West then take same observations .
• Clamp the gyro and switch off
• Move the instrument to opposite end of the baseline
and repeat process
• Check the non-spin readings and re-calibrate
instrument on surface
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B
Observational Methods
Reversal Method
-Method requires great concentration
from observer.
-Easy and simple to calculate.
Ro=(r1+2r2+r3)/4
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Stop watch/Transit Method
1.
2.
3.
4.
5.
6.
Calculate the calibration constant
TN1=N1+(C*A*T)
Calculate TN using C
Calculate Meridian Convergence (Gamma)
Calculate G.I.N
Calculate u
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Competency and training
University of Johannesburg
-Certificate issued.
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Gyro Training
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PURPOSE
GYRO USERS
UNKI MINE
METTALLON GOLD
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Gyro users
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Gyro users
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Gyro Users
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List of what can go wrong
• Inaccurate sighting of RO.(using theodolite
to sight)
• Mis appllied Convergence
• Wrong Computation.
• Home made software
• Wrong bearing of calibration base.
• Incompetence of user
• Malfunctional equipment
• Electrical Fields
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Conclusion
• The definition of Survey is Check-CheckCheck!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
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references
• Prof Angus Jamieson –University of Highlands
and islands.
• Heinne Grobbler –University of Johannesburg,
Gyro training module.
• Adriaan Oeschger – Aciel geomatics
• Schofield-Engineering survey notes
• T.L Thomas-Imperial college of science and
technology.
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