Total Station - Uses, Application, Mechanism, Advantages and more

Total Station - Uses and Application

3. Total Station
9.1Introduction
Atotalstationisanelectronic/opticalinstrumentusedinmodern
surveyingandbuildingconstruction.Thetotalstationisan
electronictheodolite(transit)integratedwithanelectronic
distancemeter(EDM)toreadslopedistancesfromtheinstrument
toaparticularpointandsoftwarerunningonanexternal
computerknownasadatacollector.Withtheaidoftrigonometry,
theanglesanddistancesmaybeusedtocalculatetheactual
positions(x,y,andzornorthing,eastingandelevation)of
surveyedpointsinabsoluteterms.

4. –Beginninginabout1980,anEDMcomponent,whichalsohad
beenimprovedtoenableautomaticreadout,wascombined
withanelectronictheodolitetocreateasingleinstrument
calledthetotalstation.
–Thefunctionsofthedistanceandanglemeasuringcomponents
werecontrolledbyaninterfacedcomputer.
–Moderntotalstationinstrumentscannowmakeslopedistance
measurements,automaticallydisplaytheresults,andalsostore
thedatainthecomputermemory.

5. –Theycanalsomeasureanglesbothinhorizontalplanesand
verticalplanes,andagaintheresultscanbeautomatically
displayedandstored.
–Theon-boardcomputercanusethesemeasureddatainreal
timetoresolvehorizontalandverticaldistances,tocalculate
thepositionsandelevationsofpoints,ortosetpointsfor
constructionprojects.
–Totalstationinstrumentsareprobablythemostcommonlyused
andimportantinstrumentsinmodernsurveyingtoday,having
practicallyreplacedalltransits,theodolites,andstandalone
EDMinstruments.

6. –Withatotalstationonemaydetermineanglesanddistances
fromtheinstrumenttopointstobesurveyed.Withtheaidof
trigonometryandtriangulation,theanglesanddistancesmay
beusedtocalculatethecoordinatesofactualpositions(X,Y,
andZornorthing,eastingandelevation)ofsurveyedpoints,or
thepositionoftheinstrumentfromknownpoints,inabsolute
terms.
–Thedatamaybedownloadedfromthetheodolitetoan
externalcomputerandapplicationsoftwarewillgeneratea
mapofthesurveyedarea.
Robotictotalstationsallowtheoperatortocontroltheinstrumentfroma
distanceviaremotecontrol.Thiseliminatestheneedforanassistantstaff
memberastheoperatorholdsthereflectorandcontrolsthetotalstationfrom
theobservedpoint.

7. •Components of a Total Station
–EDM
–Electronic theodolite
–On-Board Micro-processor
–Data Collector (built in or separate unit)
–Data Storage (internal or memory card)
–Prisms
–Keyboard and display
–Battery

8. Parts of the SET Total Station

9. Parts of the SET Total Station Contd….

10. Micro-processor
–Averages multiple angle measurements
–Averages multiple distance measurements
–Computes horizontal and vertical distances
–Corrections for temp, pressure and humidity
–Computes inverses, polar, resections
–Computes X, Y and Z coordinates

11. BriefDescriptionofImportantOperations
Electronicdistancemeasuring(EDM)instrumentisamajorpart
oftotalstation.Itsrangevariesfrom2.8kmto4.2km.The
accuracyofmeasurementvariesfrom5mmto10mmperkm
measurement.Theyareusedwithautomatictargetrecognisers.
Thedistancemeasuredisalwaysslopingdistancefrom
instrumenttotheobject.
•DistanceMeasurement:

12. AngleMeasurements:
Theelectronictheodolitepartoftotalstationisusedfor
measuringverticalandhorizontalangle.Formeasurementof
horizontalanglesanyconvenientdirectionmaybetakenas
referencedirection.Forverticalanglemeasurementvertical
upward(zenith)directionistakenasreferencedirection.The
accuracyofanglemeasurementvariesfrom2to6seconds.
WhentheslopedistanceLandslopeangleφismeasuredby
EDM,iftheelevationofpointAisthereferencepoint,wecan
findtheelevationofpointBbythefollowingformula.

13. ElevationofPointB=ElevationofPointA+HI±Lsinφ-HR

14. •DataProcessing:
Thisinstrumentisprovidedwithaninbuilt
microprocessor.Themicroprocessoraveragesmultiple
observations.Withthehelpofslopedistanceand
verticalandhorizontalanglesmeasured,whenheight
ofaxisofinstrumentandtargetsaresupplied,the
microprocessorcomputesthehorizontaldistanceand
X,Y,Zcoordinates.Theprocessoriscapableofapplying
temperatureandpressurecorrectionstothe
measurements,ifatmospherictemperatureand
pressuresaresupplied.

15. •Display:
Electronicdisplayunitiscapableofdisplayingvariousvalues
whenrespectivekeysarepressed.Thesystemiscapableof
displayinghorizontaldistance,verticaldistance,horizontaland
verticalangles,differenceinelevationsoftwoobservedpoints
andallthethreecoordinatesoftheobservedpoints.
•ElectronicBook
Eachpointdatacanbestoredinanelectronicnotebook
(likecompactdisc).Thecapacityofelectronicnotebook
variesfrom2000pointsto4000pointsdata.Surveyorcan
unloadthedatastoredinnotebooktocomputerand
reusethenotebook.

16. 9.2Featuresoftotalstations
Totalstationsarecapableofmeasuringanglesanddistances
simultaneouslyandcombineanelectronictheodolitewitha
distancemeasuringsystemandamicroprocessor.
a)Anglemeasurement
b)Distancemeasurement
c)Keyboardanddisplay
d)Softwareapplications
e)Motorisedtotalstations
f)Robotictotalstations
g)Electronicdatarecordingandprocessing

17. a)Angle Measurement
Allthecomponentsofthetotalstationsaredescribedinthe
previous.Theaxisconfigurationisidenticalandcomprisesthe
verticalaxis,thetiltingaxisandlineofsight(orcollimation).The
othercomponentsincludethetribatchwithlevelingfootscrews,
thekeyboardwithdisplayandthetelescopewhichismountedon
thestandardsandwhichrotatesaroundthetiltingaxis.Levelingis
carriedoutinthesamewayasforatheodolitebyadjustingto
centralizeaplatelevelorelectronicbubble.Thetelescopecanbe
transitedandusedinthefaceleft(orfaceI)andfaceright(or
faceII)positions.Horizontalrotationofthetotalstationaboutthe
verticalaxisiscontrolledbyahorizontalclampandtangentscrew
androtationofthetelescopeaboutthetiltingaxis.

18. b)DistanceMeasurement
Alltotalstationswillmeasureaslopedistancewhichtheonboard
computeruses,togetherwiththezenithanglerecordedbythe
lineofsighttocalculatethehorizontaldistance.Fordistances
takentoaprismorreflectingfoil,themostaccurateisprecise
measurement.Forphaseshiftsystem,atypicalspecificationfor
thisisameasurementtimeofabout1-2s,anaccuracyof(2mm+
2ppm)andarangeof3-5kmtoasingleprism.Althoughall
manufacturersquoterangesofseveralkilometerstoasingle
prism.Forthoseconstructionprojectswherelongdistancesare
requiredtobemeasured,GPSmethodsareusedinpreferenceto
totalstations.Thereisnostandarddifferenceatwhichthechange
fromonetotheotheroccurs,asthiswilldependonanumberof
factors,includingtheaccuracyrequiredandthesitetopography.
[ppm(part per million) is equivalent to an additional error of 1mm
for every kilometremeasured.]

19. SlopeandHorizontalDistances
•Boththephaseshiftandpulsedlasermethodswillmeasurea
slopedistanceLfromthetotalstationalongthelineofsighttoa
reflectorortarget.FormostsurveysthehorizontaldistanceDis
requiredaswellastheverticalcomponentVoftheslope
distance.

20. SlopeandHorizontalDistancescond….
•HorizontalDistanceD=Lcosα=Lsinz
•VerticalDistance=V=Lsinα=Lcosz
Whereαistheverticalangleandzistheisthezenith
angle.Asfarastheuserisconcerned,thesecalculations
areseldomdonebecausethetotalstationwilleither
displayDandVautomaticallyorwilldisplayLfirstand
thenDandVafterpressingbuttons.

21. c)Keyboardanddisplay
•Atotalstationisactivatedthroughitscontrolpanel,which
consistsofakeyboardandmultiplelineLCD.Anumberof
instrumentshavetwocontrolpanels,oneoneachface,which
makesthemeasiertouse.
•Inadditiontocontrollingthetotalstation,thekeyboardisoften
usedtocodedatageneratedbytheinstrument–thiscodewillbe
usedtoidentifytheobjectbeingmeasured.
•Onsometotalstationsitispossibletodetachthekeyboardand
interchangethemwithothertotalstationsandwithGPS
receivers.Thisiscalledintegratedsurveying.

22. c)Keyboardanddisplaycontd…

23. d)SoftwareApplications
•Themicroprocessorbuiltintothetotalstationisasmallcomputerand
itsmainfunctioniscontrollingthemeasurementofanglesand
distances.TheLCDscreenguidestheoperatorwhiletakingthese
measurements.
•Thebuiltincomputercanbeusedfortheoperatortocarryout
calibrationchecksontheinstrument.
•Thesoftwareapplicationsavailableonmanytotalstationsincludethe
following:
•-Slopecorrectionsandreducedlevels
•-Horizontalcircleorientation
•-Coordinatemeasurement
•-Traversemeasurements
•-Resection(orfreestationing)
•-Missinglinemeasurement
•-Remoteelevationmeasurement
•-Areas
•-Settingout

24. e)Motorisedtotalstations
•Thelatestgenerationoftotalstationshavemanyofthefeatures
describedintheprevioussectionbutarealsofittedwithservo-
motorswhichcontroltheirhorizontalandverticalmovement.
Thesearecalledmotorisedtotalstations–asshownbelow.
•Whenusingtheseinstrumentstheoperatordoesnothaveto
lookthroughthetelescopetoaligntheprismoratargetbecause
oftheservo-motors.Thishasanumberofadvantagesovera
manuallypointedsystem,sinceamotorisedtotalstationcanaim
andpointquicker,andachievebetterprecision.
•Anautomatictargetrecognitionsensorsarerequiredforthese
typesoftotalstations.

25. f)Robotictotalstations
•Althoughallmotorisedtotalstationscanbeusedas
conventionalinstrumentsmightbe,theirfullpotentialis
realisedwhentheyareremotecontrolledandusedasrobotic
totalstations.
•Byprovidingremotecontrolofthetotalstationfromthe
prism,thesearesurveyingsystemsthatpermitsingle-user
operationforeithermappingorsettingout.

26. g)Electronicdatarecordingandprocessing
•Anumberofdifferentdevicesforrecordingdataelectronically
areused.Theseincludedatacollectors(handheldcomputer),
fieldcomputerswhicharelaptopsandtabletcomputers
whichareadaptedtosurveydatacollection.

27. KeyFeaturesofTotalStations
The theodolite is offering a complete product family. It is easy for a user to
switch between models without learning a new operation.
1.Absolute circle reading
2.Excellent hardware features, such as laser plummet, endless drives on both
sides for Hz and V, brilliant optics with 30x magnification.
3.Dual-Axis compensation for reliable Hz and V reading.
4.New and intuitive software.
5.Unique leveling guidance for fast and convenient setup.
6.High resolution LCD display.
7.Audible notice for 90°turns and layout.
8.Electronic laser distance measurement.
9.Free set-up possible straight from blueprint.
10.Graphic sketches.
11.Hassle-free EDM measurement with red laser on any target or on the flat-
prism.
12.Enter the data at the office and simply call it up at the site.
13.Upload and transfer data via on board data connection.
14.Data editing and exchange in Total Stations.
15.Connectivity to 3rd party devices.

28. 9.4FieldProcedureforTotalStationinTopographicSurveying
1.Prior to Physical Setup of the Total Station
2.Tripod Setup
3.Mounting the Total Station
4.Setting up (Leveling) the Total Station
a) Centering
b) Leveling
c) Focusing
5.Setting up Prism over the Station
6.Powering Up the Total Station
7.Powering Up the Palmtop Computer
8.Communication Techniques
9.Coding Specific Points
10.Data Downloading, Manipulation and Software
11.Preparation of Maps

29. Leveling the Total Station
•LevelingtheTotalStationmustbeaccomplishedtosufficient
accuracyotherwisetheinstrumentwillnotreportresults
•Levelingtheinstrumenttakes30to45minutes
-makesureyoucanseealltargetsfromtheinstrument
stationbeforegoingthroughtheprocess

30. Step1:TripodSetup
•Tripod legs should be
equally spaced
•Tripod head should be
Approximately level
•Head should be directly
over survey point

31. Step2:MountInstrumentonTripod
•Place Instrument on Tripod
•Secure with centering screw
while bracing the instrument
with the other hand
•Insert battery in instrument
before leveling

32. Step3:FocusonSurveyPoint
•Focus the optical plummet on the survey point

33. Step4:LevelingtheInstrument
•Adjust the leveling foot screws
to center the survey point in
the optical plummet reticle
•Center the bubble in the
circular level by adjusting the
tripod legs

34. Step4:Leveling…
•Loosenthehorizontalclampandturninstrumentuntilplate
levelisparallelto2ofthelevelingfootscrews
•Centerthebubbleusingthelevelingscrews-thebubblemoves
towardthescrewthatisturnedclockwise
•Rotatetheinstrument90degreesandlevelusingthe3rd
levelingscrew

35. Step4:Leveling…
•Observethesurveypointintheopticalplummetandcenter
thepointbylooseningthecenteringscrewandslidingthe
entireinstrument
•Afterre-tighteningthecenteringscrewchecktomakesure
theplatelevelbubbleislevelinseveraldirections

36. Step5:ElectronicallyVerifyLeveling
•Turnontheinstrumentbypressing
andholdingthe“on”button(you
shouldhearanaudiblebeep)
•Theopeningscreenwillbethe
“MEAS”screen.Selectthe[Tilt]
function
•Adjustthefootlevelscrewsto
exactlycentertheelectronic
“bubble”
•Rotatetheinstrument90degrees
andrepeat

37. Step6:AdjustImage&ReticleFocus
•Releasethehorizontal&verticalclamps
andpointtelescopetoafeaturelesslight
background
•Adjustthereticule(i.e.cross-hair)focus
adjustmentuntilreticleimageissharply
focused
•Pointtelescopetotargetandadjustthe
focusringuntiltargetisfocused
•Moveyourheadfromside-to-sidetotest
forimageshift(i.e.parallax).Repeatthe
reticlefocusstepifparallaxissignificant
•NOTE:Whentheinstrumentoperator
changesthereticlefocusmayneedtobe
adjusted

38. MeasuringtheHeightofAnObject
Leveltheinstrumentatasitewherethetargetcanbeviewedthroughthe
telescopeandthemirrortargetcanbesetupdirectlybelowthetargetAfter
poweringontheinstrumentselect“REM”from“MEAS”>“Menu”.
Ht=h1+h2
h2=S(sinθz1)(cotθz2)–S(cosθz1)
NOTE:Instrumentheightdoesnotaffectthiscalculation

39. AdvantagesofUsingTotalStations
1.Fieldworkiscarriedoutveryfast.
2.Accuracyofmeasurementishigh.
3.Manualerrorsinvolvedinreadingandrecordingareeliminated.
4.Calculationofcoordinatesisveryfastandaccurate.Even
correctionsfortemperatureandpressureareautomatically
made.
5.Computerscanbeemployedformapmakingandplotting
contourandcross-sections.Contourintervalsandscalescanbe
changedinnotime.