INTRO TO GNSS AND MACHINE CONTROL FOR CONSTRUCTION THE BASICS USES PRECISION AND ACCURACY SOFTWARE HARDWARE MACHINE CONTROL PERIPHERALS COST/BENEFIT INTRO.

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

The Basics

THE LANGUAGE GNSS - GPS AND GLONASS TOTAL POSITIONING SYSTEM - TPS COORDINATES AND VECTORS GOOGLE EARTH AND NAVIGATION GIS

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

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

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

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.

Basics - DGPS (ground or satellite based correction)

Satellite WAAS OmniStar

Local USCG CORS Fee Networks Base Station

Basics - Ellipsoid/Geoid (NAD83)

Ellipsoid - Uniform approximation of sea levelGeoid – Non-uniform approximation of sea level based on the Influence of Earth’s gravity and rotation

Basics - Projection (Calif. Coord. Sys)

Basics California Coordinate System-Zones

BasicsTPS- 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

Basics - TPS - CONSTRUCTION

BasicsCADD – Coordinates & Vectors

Coordinates & COGO Entities Layers CAD vs Images

– Flexibility– Repeatability– Distances/Areas/Volumes– Dynamic

BasicsPaper/PDF/JPG/Raster image

Basics – CADD, all layers on

Basic – CADD, some layers off

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

USES

SURVEYING TOPOGRAPHY TAKEOFF LAYOUT/STAKEOUT DIGITAL TERRAIN MODELS DTM

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

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

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

Uses - Layout/Stakeout

Grade/slope stakes Structures and hardscapes Utilities

– Plot existing– Locate new

Easily check for conflicts

Uses – Digital Models (DTM)

Tracking progress Measuring volumes Warning zones Guidelines Indicate only systems Machine control

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

Precision – How is it measured

CEP & DRMS

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 inconsistentbetween products and manufacturers

Precision - Typical Example

Channel ConfigurationChannels 120

Signal TrackingGPS: L1, L2, L2CGLONASS: L1, L2Galileo: E1, GIOVE-A/GIOVE-B (test)CompassSBAS

Horizontal Position Accuracy (RMS)Single Point L1 1.5 mSingle Point L1/L2 1.2 mSBAS4 0.6 mDGPS 0.4 mRT-205 0.2 mRT-2™ 1 cm+1 ppmInitialization time < 10 sInitialization reliability > 99.9%

Measurement Precision (RMS)Fully independent code and carrier measurements:

GPS GLOL1 C/A Code 4 cm 8 cmL1 Carrier Phase 0.5 mm 1 mmL2 P(Y) Code6 8 cm 8 cmL2 Carrier Phase6 1 mm 1 mmL2C code7 8 cm 8 cmL2C carrier phase7 0.5 mm 0.5 mm________________________________________Typical values. Performance specifications subject to GPS system characteristics, US DOD operational degradation, ionospheric and tropospheric conditions, satellite

Precision – Approximate Cost

Low-Cost Sub-Meter Sub-Foot Sub-Inch

<$400 $1k – 4k $5k – 10k >$24k

6-15 ft < 3 ft < 6 in < .5 in

WAAS WAAS +(usually requires external

antenna)

OmniStar(requires subscription)

RTK(requires base station or

subscription)

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

SOFTWARE

Field Data Collector– SURVEY/TOPO/LAYOUT - CADD based– GIS

Office – SURVEY– CIVIL DESIGN– TAKEOFF– GIS

Machine Control – Proprietary in-cab

HARDWARE

RECEIVER CONTROLLER/COMPUTER RODS AND TRIPODS RADIOS

– UHF/Spread Spectrum– BLUETOOTH– CELL

MACHINE CONTROL

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

Receiver w/ Remote Antenna

Some data collectors have GNSS receivers built-in and require a rod mounted antenna for increased accuracy

Data Collectors

MACHINE CONTROL

ELEVATION CONTROL SIDE SLOPE ALIGNMENT GPS AND LASER HYDRAULICS CONTROLLERS/MONITORS FIRMWARE AND SOFTWARE

PERIPHERALS

SONAR LIGHT BARS DISTANCE LASERS PIPE/WIRE FINDERS INCLINOMETERS MASTS LASERS

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

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?