Developments in Total Stations

8/13/2019 Developments in Total Stations

1/11

T h e U n i v e r s i t y o f S o u t h e r n Q u e e n s l a n dT h e U n i v e r s i t y o f S o u t h e r n Q u e e n s l a n d

Developments in TotalDevelopments in Total

StationsStations

Recent developments in Total Stations haveRecent developments in Total Stations have

included a range of new features andincluded a range of new features and

developments that have taken us to wheredevelopments that have taken us to where

we are today.we are today.


Developments in TotalDevelopments in Total

StationsStations

Some of these developments will now beSome of these developments will now be

examined and include:examined and include:

Development of Electronic AngleDevelopment of Electronic AngleMeasurementMeasurement

Axis compensationAxis compensation MotorisationMotorisation and roboticsand robotics

Developments in onboard softwareDevelopments in onboard software

Storage media and memory managementStorage media and memory management

Developments in onboard softwareDevelopments in onboard software


2/11


Developments in Electronic AngleDevelopments in Electronic Angle

MeasurementMeasurement

Traditional system of angle measurementTraditional system of angle measurementrequired the use of micrometers to read andrequired the use of micrometers to read and

interpolate the inscribed glass plate ofinterpolate the inscribed glass plate of theodolitetheodolite..

The reading involved a number of possible errorsThe reading involved a number of possible errors

including:including:

Initial pointing error to the targetInitial pointing error to the target

Reading error of reading and interpolating theReading error of reading and interpolating the

angle between the divisionsangle between the divisions

Transcription errorsTranscription errors




To a large extent the last two errors (Reading andTo a large extent the last two errors (Reading and

transcription error) have been eliminated.transcription error) have been eliminated.

Electronic Angle Measurement is now generallyElectronic Angle Measurement is now generally

completed by one of two techniques:completed by one of two techniques:

IncIncremental Measurement, orremental Measurement, or

Absolute MeasurementAbsolute Measurement


3/11



MeasurementMeasurementIncremental Measurement TechniqueIncremental Measurement Technique

Incremental Measurement TechniqueIncremental Measurement Technique

Glass plate coded with black and clear intervalsGlass plate coded with black and clear intervals

eg 1024 intervalseg 1024 intervals

Light is passed through plate and detected byLight is passed through plate and detected by

photo diodes (light detectors).photo diodes (light detectors).

Photo diodes convert light to electronic readingPhoto diodes convert light to electronic reading

(count).(count).


Developments in Electronic AngleDevelopments in Electronic AngleMeasurementMeasurement

Incremental Measurement TechniqueIncremental Measurement Technique


4/11




Incremental Measurement TechniqueIncremental Measurement Technique (cont)(cont)

As total station rotates the number of intervalsAs total station rotates the number of intervals

are counted and converted into an angle. Oneare counted and converted into an angle. One

photo diode is fixed at a zero mark and the otherphoto diode is fixed at a zero mark and the other

moves with the total station. Number of intervalsmoves with the total station. Number of intervals

between the fixed and moveable photo diodes arebetween the fixed and moveable photo diodes are

determined.determined.

Whole number of intervals (n) is counted and theWhole number of intervals (n) is counted and the

partial division is determined by measuring thepartial division is determined by measuring thephase anglephase angle




Absolute Measurement TechniqueAbsolute Measurement Technique

glass plate divided up into a number ofglass plate divided up into a number ofgraduations Eg for T1010 circle has 1152graduations Eg for T1010 circle has 1152

graduations and each graduation has 128graduations and each graduation has 128

sectors, each sector is binary encoded egsectors, each sector is binary encoded eg

0000000 to 111111.0000000 to 111111.

Light Emitting Diode (LED) passes through circleLight Emitting Diode (LED) passes through circle

and detected on photo diode array. Angle isand detected on photo diode array. Angle is

measured in two parts: determining the sectormeasured in two parts: determining the sector

and then the part of the sectorsand then the part of the sectors..


5/11




Absolute Measurement Technique (cont)Absolute Measurement Technique (cont) So rather than counting the intervals the angle isSo rather than counting the intervals the angle is

measured directly from the graduations. Themeasured directly from the graduations. The

photo diode moves around in the case of thephoto diode moves around in the case of the

horizontal circle and remains fixed for the verticalhorizontal circle and remains fixed for the vertical

circlecircle..



MeasurementMeasurementAxis CompensationAxis Compensation

All new total stations have automatic axisAll new total stations have automatic axiscompensation to correct for errors in tilt in thecompensation to correct for errors in tilt in thehorizontal and vertical axes.horizontal and vertical axes.

Conventional systems used a plate bubble for theConventional systems used a plate bubble for the

horizontal levelling and a pendulum sensor forhorizontal levelling and a pendulum sensor forthe vertical axis compensator.the vertical axis compensator.

Electronic tilt sensors are usually liquid typeElectronic tilt sensors are usually liquid typecompensation systems with either:compensation systems with either:

Magnetic detection orMagnetic detection or

Photodiode detectionPhotodiode detection


6/11



MeasurementMeasurementAxis Compensation (Magnetic Detection)Axis Compensation (Magnetic Detection)

the movement of the liquid in the sensor isthe movement of the liquid in the sensor ismeasured by the magnetic measurement ofmeasured by the magnetic measurement of

electronic coils. A voltage differential determineselectronic coils. A voltage differential determines

the position of the fluid.the position of the fluid.




((photo diode detection methodphoto diode detection method))

the level is sensed and detected by passing lightthe level is sensed and detected by passing light

from an LED through the level vial. Transmittedfrom an LED through the level vial. Transmitted

light is detected with the amount of incident lightlight is detected with the amount of incident lightindicating the varying as a result of the positionindicating the varying as a result of the positionof the liquid.of the liquid.


7/11




((photo diode detection methodphoto diode detection method))



MeasurementMeasurementSingle Axis CompensationSingle Axis Compensation

Corrects forCorrects for

the tilt in thethe tilt in the

vertical axisvertical axis..


8/11



MeasurementMeasurementDual Axis CompensationDual Axis Compensation

Dual Axis compensation corrects for theDual Axis compensation corrects for theinclination of the vertical axis not only in theinclination of the vertical axis not only in the

direction of pointing but in the direction of thedirection of pointing but in the direction of the

truniontrunion axis. Tilt in theaxis. Tilt in the truniontrunion axis producesaxis produces

errors in horizontal angles particularly in steeperrors in horizontal angles particularly in steep

vertical sights.vertical sights.

An error of 60An error of 60 results in errors of 11results in errors of 11 at 10at 10

andand7272 at 50at 50..



MeasurementMeasurementDual Axis CompensationDual Axis Compensation


9/11



MeasurementMeasurementMotorised Total StationsMotorised Total Stations

Motorised systems are characterised by:Motorised systems are characterised by:

Horizontal and vertical servo motorHorizontal and vertical servo motor

Motors operate at high (course) and slow (fine)Motors operate at high (course) and slow (fine)

speedsspeeds

No tangent screws requiredNo tangent screws required

Very good forVery good for setoutsetout of pointsof points

Price approx $12Price approx $12--$16K$16K



MeasurementMeasurementSelf Tracking Total StationSelf Tracking Total Station

The self tracking systems allow the automatic tracking of aThe self tracking systems allow the automatic tracking of aprism.prism.

The systems is characterised by:The systems is characterised by:

Basic motorised system plusBasic motorised system plus

Laser tracking system parallel to lens systemLaser tracking system parallel to lens system Track at high speedsTrack at high speeds

Automatic search routine when lock is lostAutomatic search routine when lock is lost

Focus not requiredFocus not required

Faster and more accurate then human pointingFaster and more accurate then human pointing

Can operate at night or low light conditionsCan operate at night or low light conditions

Inbuilt communications to indicate that system isInbuilt communications to indicate that system isreadingreading

Approx cost $17Approx cost $17--$25K$25K


10/11



MeasurementMeasurementRobotic SystemRobotic System

Robotic system is the next step up fromRobotic system is the next step up fromthe self tracking system and includes allthe self tracking system and includes allthe features of a self tracking systemthe features of a self tracking systemplus:plus:

Robotic softwareRobotic software

Telemetry linkTelemetry link

Remote control unit with key padRemote control unit with key padentryentry

Requires only one personRequires only one person Surveyor may require assistanceSurveyor may require assistance

when placing pegswhen placing pegs

Approx cost $30Approx cost $30 --$40K$40K



MeasurementMeasurementReflectorlessReflectorless Total StationsTotal Stations

Developed to allow measurement toDeveloped to allow measurement to

virtually any surface without the needvirtually any surface without the need

to utilise a prism.to utilise a prism.

CharcterisedCharcterised by:by: Measure approx 80m w/o prismMeasure approx 80m w/o prism

Measure buildings and structuresMeasure buildings and structures

with one person eg tunnel profilingwith one person eg tunnel profiling

+/+/-- 3mm3mm

limited by surface reflectance andlimited by surface reflectance and

light conditionslight conditions


11/11



MeasurementMeasurementReflectorlessReflectorless Total StationsTotal Stations

Developed to allow measurement to virtually anyDeveloped to allow measurement to virtually anysurface without the need to utilise a prism.surface without the need to utilise a prism.

CharcterisedCharcterised by:by:

Measure approx 80m w/o prismMeasure approx 80m w/o prism

Measure buildings and structures with oneMeasure buildings and structures with one

person eg tunnel profilingperson eg tunnel profiling

+/+/-- 3mm3mm

limited by surface reflectance and lightlimited by surface reflectance and lightconditionsconditions

Documents

Developments in Total Stations