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AMSZ AGM 2014

A brief look into Gyro- Theodolite technology and its application

NYANGA 29 AUGUST 2014

TENDAI O. CHENGUMINE SURVEYOR ( UNKI MINES)

IMPORTANT!

THE GYRO THEODOLITE

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History

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• 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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Principle of operation

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PURPOSE

• 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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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.

SURVEY

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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

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• 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

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• 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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Initial survey requirements:

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PURPOSE

a)Gyro Calibration base.• Must be robust• Must be linked to U/G Survey • Secured, close to mine, wind shields.b) Softwarec) Meridian convergence tables

CHECKING UNDERGROUND LINE

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• 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 .

PROCEDURE OF CHECKING UNDERGROUND LINE

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• 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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Reversal Method-Method requires great concentration from observer.-Easy and simple to calculate.

Ro=(r1+2r2+r3)/4

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Observational Methods

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Stop watch/Transit Method

1. Calculate the calibration constant2. TN1=N1+(C*A*T)3. Calculate TN using C4. Calculate Meridian Convergence (Gamma)5. Calculate G.I.N 6. Calculate u

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Competency and training

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University of Johannesburg-Certificate issued.

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Gyro Training

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GYRO USERS

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PURPOSE

UNKI MINEMETTALLON 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-Check-Check!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

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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.