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Published byMiranda Lindsey Modified over 9 years ago
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INTRO TO GNSS AND MACHINE CONTROL FOR CONSTRUCTION THE BASICS USES PRECISION AND ACCURACY SOFTWARE HARDWARE MACHINE CONTROL PERIPHERALS COST/BENEFIT INTRO TO SOFTWARE AND HARDWARE TOOLS
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The Basics THE LANGUAGE GNSS - GPS AND GLONASS TOTAL POSITIONING SYSTEM - TPS COORDINATES AND VECTORS GOOGLE EARTH AND NAVIGATION GIS
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Basics - Language GNSS/GPS/GLONASS – DGPS – WAAS/OMNI-STAR/RTK – CORS - INTERNET/ NETWORK – BASE/ROVER ALTITUDE, ELEVATION – ELLIPSOID/GEOID/PROJECTION LOCALIZATION, NAD83, WGS84 – CALIFORNIA COORD. SYS – LOCAL COORD. SYS NEMA/RTCM/CMR GLIDE/FLOODLIGHT CAD/CADD – COORDINATE GEOMETRY/COGO – DESIGN/TAKEOFF – DIGITAL TERRAIN MODEL/DTM GIS/GEORERENCED – GOOGLE EARTH – ESRI/ARCMAP/*.SHP SURVEY/LAYOUT GNSS – RECIEVERS & RADIOS – CONTROLLERS – UHF/BLUETHOOTH – RS232, LEMO, USB – MHz, KHz, WATTS TPS - TOTAL STATION, ROBOTIC TOTAL STATION – INVERSE, TRAVERSE, BACKSITES, FORESIGHTS – REFLECTOR, REFLECTORLESS – PRISMS, PRISM OFFSETS LASER LEVELING MACHINE CONTROL – DTM – GNSS/LASER/SLOPE SENSORS – INDICATE – HYDRAULICS – FIRMWARE/SOFTWARE
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Basics - A few acronyms GNSS – Global Navigation Satellite System GPS – Global Positioning System DGPS – Deferential GPS WAAS – Wide Area Augmentation System (satellite based) SBAS – Satellite Based Augmentation System Omni-Star – Proprietary SBAS RTK – Real Time Kinematic CORS – Continuously Operating Reference Stations NAD83 – North American Datum of 1983 (reference ellipsoid) WGS84 – World Geodetic System of 1984 (reference ellipsoid) UTM – Universal Transverse Mercator coordinate system
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Basics - A few more acronyms NMEA – National Marine Electronics Association RTCM – Radio Technical Commission for Maritime Services CMR – Compact Measurement Record (was proprietary) CAD/CADD - Computer Aided Design /Design and Drafting COGO – Coordinate Geometry DTM – Digital Terrain Models GIS – Geographic Information System ESRI – Environmental Systems Research Institute (private company) SHP - Shapefile TPS – Total Positioning System UHF – Ultra High Frequency
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Basics - GPS and GLONASS A typical view of a GNSS satellite map showing satellites usable to obtain a accurate position courtesy of Carlson SurvCE software.
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Basics - DGPS (ground or satellite based correction) Satellite WAAS OmniStar Local USCG CORS Fee Networks Base Station
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Basics - Ellipsoid/Geoid (NAD83) Ellipsoid - Uniform approximation of sea level Geoid – Non-uniform approximation of sea level based on the Influence of Earth’s gravity and rotation
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Basics - Projection (Calif. Coord. Sys)
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Basics California Coordinate System-Zones
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Basics TPS- Total Positioning System Typically used to mean Total Station Can include total station, levels, lasers, and theodolites Usually more accurate than GPS Does not require clear view of sky More dependent on control points and benchmarks
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Basics - TPS - CONSTRUCTION
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Basics CADD – Coordinates & Vectors Coordinates & COGO Entities Layers CAD vs Images – Flexibility – Repeatability – Distances/Areas/Volumes – Dynamic
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Basics Paper/PDF/JPG/Raster image
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Basics – CADD, all layers on
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Basic – CADD, some layers off
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Basics - GIS Ground/Aerial/Satellite based Mapping Geo-Referenced (latitude and longitude) Data referenced to specific locations ESRI, ArcMap, ArcView, *.SHP Recording, tracking, monitoring everything – Census – Utilities – Maintenance & Repairs
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USES SURVEYING TOPOGRAPHY TAKEOFF LAYOUT/STAKEOUT DIGITAL TERRAIN MODELS DTM
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Uses - Surveying Property Survey Control – Owner determines control – Regional/Statewide grid UTM California Coordinate System – Local jobsite coordinates (1000,1000,100) Minimum 4 valid control points required for localization, more is better
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Uses - Topography Check existing grades before/after bid Supplement data on plans before/after bid Track earthwork volumes and other installed line item quantities for progress payments Measure and record final pay quantities Data as-builts Data for change orders
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Uses - Takeoff Digitize PDF drawings for CADD applications Coordinate geometry works for you Many CADD based tools Calculate volumes using digital models Dynamic – changes are easily accounted for once plans are digitized
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Uses - Layout/Stakeout Grade/slope stakes Structures and hardscapes Utilities – Plot existing – Locate new Easily check for conflicts
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Uses – Digital Models (DTM) Tracking progress Measuring volumes Warning zones Guidelines Indicate only systems Machine control
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PRECISION AND ACCURACY How measured Typical accuracies – Non-Differential GNSS – 10 meters – Satellite/Beacon based DGPS – 2-5 meters – Post Processing <1cm – RTK <1cm Network/CORS Local Base Station Accuracy in the field
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Precision – How is it measured CEP & DRMS
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Precision - Typical Example AMXU GPS Receiver* UBlox 50 channel GPS, L1 frequency, C/A Code Time To First Fix: <1 second (hot start); <32 sec. (Cold start) Sensitivity: -160dBm Accuracy: Autonomous <2.5m; SBAS <2m Update Rate: 1Hz (1 second) Velocity & Heading accuracy: 0.1m/sec Includes AMXU GPS Setup Utility USFS Dense Tree Canopy Tested *GPS accuracy depends on multipath environment, antenna orientation, number of satellites in view, satellite geometry, and ionospheric activity Information furnished by manufactures is confusing and inconsistent between products and manufacturers
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Precision - Typical Example Channel Configuration Channels120 Signal Tracking GPS: L1, L2, L2C GLONASS: L1, L2 Galileo: E1, GIOVE-A/GIOVE-B (test) Compass SBAS Horizontal Position Accuracy (RMS) Single Point L11.5 m Single Point L1/L21.2 m SBAS40.6 m DGPS0.4 m RT-2050.2 m RT-2™1 cm+1 ppm Initialization time< 10 s Initialization reliability> 99.9% Measurement Precision (RMS) Fully independent code and carrier measurements: GPSGLO L1 C/A Code4 cm8 cm L1 Carrier Phase0.5 mm1 mm L2 P(Y) Code68 cm8 cm L2 Carrier Phase61 mm1 mm L2C code78 cm8 cm L2C carrier phase70.5 mm0.5 mm ________________________________________ Typical values. Performance specifications subject to GPS system characteristics, US DOD operational degradation, ionospheric and tropospheric conditions, satellite
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Precision – Approximate Cost Low-CostSub-MeterSub-FootSub-Inch <$400$1k – 4k$5k – 10k>$24k 6-15 ft< 3 ft< 6 in<.5 in WAASWAAS + (usually requires external antenna) OmniStar (requires subscription) RTK (requires base station or subscription)
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Accuracy in the Field Satellite – Satellite Geometry (how many and where) GPS or GPS/GLONASS – Ionospheric conditions – Multipath (interference) Cellular (can you hear me now) Radio – Line of sight – Power
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SOFTWARE Field Data Collector – SURVEY/TOPO/LAYOUT - CADD based – GIS Office – SURVEY – CIVIL DESIGN – TAKEOFF – GIS Machine Control – Proprietary in-cab
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HARDWARE RECEIVER CONTROLLER/COMPUTER RODS AND TRIPODS RADIOS – UHF/Spread Spectrum – BLUETOOTH – CELL MACHINE CONTROL
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Survey Receivers The roving receiver usually includes batteries and radio, mounted on a 2 meter rod connected to a data collector via cable or bluetooth
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Receiver w/ Remote Antenna Some data collectors have GNSS receivers built-in and require a rod mounted antenna for increased accuracy
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Data Collectors
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MACHINE CONTROL ELEVATION CONTROL SIDE SLOPE ALIGNMENT GPS AND LASER HYDRAULICS CONTROLLERS/MONITORS FIRMWARE AND SOFTWARE
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PERIPHERALS SONAR LIGHT BARS DISTANCE LASERS PIPE/WIRE FINDERS INCLINOMETERS MASTS LASERS
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COST EFFICIENCIES Initial Investment – HARDWARE – SOFTWARE – LABOR (learning curve,installation,maintenance) PAYBACK – Better control of progress and payments – Increased efficiency of operation – Better and faster data for change orders – Identify/anticipate problems sooner
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COMMON QUESTIONS What is the “price”? What brand? Which applications? How exactly will it save me money and how much? How long will it take to payoff the equipment? How much training will it take and are my people up- to-it? Do I need everything now or is there a phased-in approach?
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