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Introduction to UAV
(Unmanned Aerial Vehicle)
PROF. RAFFAELA CEFALO
ENG. ANDREA CALLIARI, ENG. FRANCESCO CESCUTTI
GEODESY AND SATELLITE NAVIGATION LABORATORY
UNIVERSITY OF TRIESTE, ITALY
GeoSNav Lab Geodesy and Satellite Navigation Laboratory
UNIVERSITY of TRIESTE ITALY
UAV (UNMANNED AERIAL VEHICLE)
An unmanned aerial
vehicle (UAV), commonly known
as a drone and also referred to
as an unpiloted aerial
vehicle and a remotely piloted
aircraft (RPA) by the International
Civil Aviation Organization
(ICAO), is an aircraft without a
human pilot aboard.
RPAS/UAV/DRONES
Remotely Piloted Aircraft Systems (RPAS),
UAV (Unmanned Aerial Vehicle)
The development of drones (RPAS or Unmanned Aircraft Systems) started in the 50's and matured rapidly in recent years in the military context. Drones are now entering the civil market, opening a promising new chapter in the history of aviation.
Civil drones present a huge potential for developing innovative applications in wide variety of sectors to the benefit of European society, creating jobs and achieving useful tasks.
As civil aviation is evolving itself towards more automation, drones' technologies will also be crucial for the competitiveness of the European aeronautics industry as a whole.
UAV tipologies
Rotary Wing Vs Fixed Wing UAVs
Fixed Wing
Higher speeds
Longer run distances
Minor battery consumption
Rotary Wing
More adaptable, better dynamics
higher weight capabilities
Possibility to stay fixed on a point
Civil Applications of RPAS
RPAS USE CASES
Precision agricolture
Infrastructure inspection
Wind energy monitoring
Pipeline and power
inspection
Highway monitoring
Natural resources
monitoring
RPAS USE CASES
Atmospheric research
Media and Entertaiment
Sports photos
Filming
Wildlife research
Hunting and anti-hunting
monitoring
Disaster relief
Other Use cases
Precision agricultures and fisheries
Power or gas line monitoring
Infrastructure inspection
Communications and broadcast services
Wireless communication relay and satellite augmentation system
Natural resources monitoring
Media and entertainment
Digital mapping
Land and wildlife management
Air quality control and management.
Advantages
The RPAS, commonly known as
drones, are systems comprising an
aircraft, a ground control where the
pilot is based and a data link.
Being remotely piloted they are well
suited for long duration monitoring
tasks or risky flights into ash clouds or
in proximity to nuclear or chemical
plants after major incidents.
RPAS reduce human life exposure
and provide economic savings and
environmental benefits.
Advantages
less fuel consumption
less CO2 emissions and
less noise than manned aircraft.
They can efficiently complement existing manned aircraft or satellite
infrastructure used by government in crisis management, law
enforcement, border control or fire fighting.
RPAS can be light, flexible and affordable for a great number of
commercial applications:
Application areas
APR Civil Applications:
• Aerophotogrammetry and architectural surveys
• Archaeological sites monitoring
• Industrial plants monitoring
• Environmental monitoring – natural and anthropic disasters
• High accuracy monitoring in agricolture
• Biodiversity and fauna monitoring
• Search and Rescue operations
• Videos and photos
Application areas
APR Civil Applications:
• Aerophotogrammetry and architectural surveys
• Archaeological sites monitoring
• Industrial plants monitoring
• Environmental monitoring – natural and anthropic disasters
• High accuracy monitoring in agricolture
• Biodiversity and fauna monitoring
• Search and Rescue operations
• Videos and photos
Disaster Prevention
Use in Researches finalized to the prevention and mitigation of natural and anthropicdisasters:
Natural disasters:
Earthquakes, volcanic eruptions, tsumanis, etc.
Land slides, rock avalanches, etc.
Tornadoes, hurricanes, wild fires etc.
Anthropic disasters:
Infrastructures collapses (bridges, buildings, etc.)
Atmospheric/Earth/Marine dangerous pollutions, biological disasters
Terroristic attacks, chemical and oil spills, etc
Forest fire detection
Prevention and early detection of forest fires.
The possibility of constant flight, both day and night, makes the methods
used until now (helicopters, watchtowers, etc.) become obsolete.
Cameras and sensors that provide real-time emergency services,
including information about the location of the outbreak of fire as well as
many factors (wind speed, temperature, humidity, etc.) that are helpful
for fire crews to conduct fire suppression.
Applications to Archaeology
In Peru archaeologists use drones to speed up survey work and protectsites from squatters, builders and miners.
Small drones helped researchers produce three-dimensional models of Peruvian sites instead of the usual flat maps – and in days and weeks instead of months and years.
Drones have replaced expensive and clumsy small planes, kites and helium balloons. Drones costing as little as £650 have proven useful.
In 2013 drones flew over at least six Peruvian archaeological sites, including the colonial Andean town Machu Llacta 4,000 metres (13,000 ft) above sea level.
Jeffrey Quilter, an archaeologist with Harvard University said, "You can go up three metres and photograph a room, 300 metres and photograph a site, or you can go up 3,000 metres and photograph the entire valley."
In September 2014 drones weighing about 0.5 kg were used for 3D mapping of the above-ground ruins of the Greek city of Aphrodisias.
Flight control
Each rotor produces both a thrust and torque about its
center of rotation, as well as a drag force opposite to
the vehicle's direction of flight.
If all rotors are spinning at the same angular velocity,
with rotors 1 and 3 rotating clockwise and rotors 2 and 4
counterclockwise, the net aerodynamic torque, and
hence the angular acceleration about the yaw axis, is
exactly zero, which implies that the yaw stabilizing rotor
of conventional helicopters is not needed.
Yaw is induced by mismatching the balance in
aerodynamic torques (i.e., by offsetting the cumulative
thrust commands between the counter-rotating blade
pairs).
Schematic of reaction torques on
each motor of a quadcopter aircraft,
due to spinning rotors.
Rotors 1 and 3 spin in one direction,
while rotors 2 and 4 spin in the
opposite direction, yielding opposing
torques for control.
Pitch, Roll and Yaw Axes
Vertical axis (yaw)
Yaw axis is a vertical axis through an aircraft, or similar body, about which the body yaws; it may be a body, wind, or stability axis. Also known as yawing axis.
The yaw axis is defined to be perpendicular to the body of the wings with its origin at the center of gravity and directed towards the bottom of the aircraft. A yaw motion is a movement of the nose of the aircraft from side to side. The pitch axis is perpendicular to the yaw axis and is parallel to the body of the wings with its origin at the center of gravity and directed towards the right wing tip.
A pitch motion is an up or down movement of the nose of the aircraft. The roll axis is perpendicular to the other two axes with its origin at the center of gravity, and is directed towards the nose of the aircraft. A rolling motion is an up and down movement of the wing tips of the aircraft. The rudder is the primary control of yaw.
Lateral axis (pitch)
The lateral axis (also called transverse axis) passes through the plane from wingtip to wingtips. Rotation about this axis is called pitch. Pitch changes the vertical direction the aircraft's nose is pointing. The elevators are the primary control of pitch.
Longitudinal (roll)
The longitudinal axis passes through the plane from nose to tail. Rotation about this axis is called bank or roll. Bank changes the orientation of the aircraft's wings with respect to the downward force of gravity. The pilot changes bank angle by increasing the lift on one wing and decreasing it on the other. This differential lift causes bank rotation around the longitudinal axis. The ailerons are the primary control of bank. The rudder also has a secondary effect on bank.
Vertical axis (yaw)
Yaw axis is a vertical axis through an aircraft, or similar body, about which the body yaws; it may be a body, wind, or stability axis. Also known as yawing axis.
The yaw axis is defined to be perpendicular to the body of the wings with its origin at the center of gravity and directed towards the bottom of the aircraft. A yaw motion is a movement of the nose of the aircraft from side to side.
The pitch axis is perpendicular to the yaw axis and is parallel to the body of the wings with its origin at the center of gravity and directed towards the right wing tip.
Pitch and Roll
Lateral axis (pitch)
The lateral axis (also called transverse axis) passes through the plane from wingtip to wingtips. Rotation about this axis is called pitch. Pitch changes the vertical direction the aircraft's nose is pointing. The elevators are the primary control of pitch.
Longitudinal (roll)
The longitudinal axis passes through the plane from nose to tail. Rotation about this axis is called bank or roll. Bank changes the orientation of the aircraft's wings with respect to the downward force of gravity.
Pitch motion
A pitch motion is an up or down
movement of the nose of the aircraft.
The roll axis is perpendicular to the
other two axes with its origin at the
center of gravity, and is directed
towards the nose of the aircraft. A
rolling motion is an up and down
movement of the wing tips of the
aircraft. The rudder is the primary
control of yaw.
Altitude and attitude control
A quadrotor hovers or adjusts its altitude by applying equal thrust to all four rotors.
A quadrotor adjusts its
yaw by applying more
thrust to rotors rotating
in one direction.
A quadrotor adjusts its pitch
or roll by applying more thrust
to one rotor and less thrust to
its diametrically opposite
rotor.
Quadcopters
Small quadcopters are subject to normal rotorcraft aerodynamics, includingvortex ring state.
Mechanical
Main mechanical components needed for construction:
the frame, propellers (either fixed-pitch or variable-pitch), and the electricmotors.
For best performance and simplest control algorithms, the motors and propellers should be placed equidistant.
Recently, carbon fiber composites have become popular due to their light weightand structural stiffness.
The electrical components needed to construct a working quadcopter are similar to those needed for a modern RC helicopter. They are the electronicspeed control module, on-board computer or controller board, and battery.
Quadcopters
Quadcopters are a useful tool for university researchers to test and evaluate
new ideas in a number of different fields, including fightcontrol theory, navigation, real time systems and robotics.
In recent years many universities have shown quadcopters
performing increasingly complex aerial manoeuvres.
There are numerous advantages to using quadcopters as
versatile test platforms.
Quadcopters - advantages
they are relatively cheap
available in a variety of sizes and
their simple mechanical design means that they can
be built and maintained by amateurs.
UAV - Advantages
Low costs
Automation in the acquisition process
Quickness in the survey execution
Ability to map areas with reducedor no access
UAVs Seminars/Thesis
at GeoSNav Lab
Civil Engineering – Master Degree Thesis
eng. Andrea Calliari
eng. Francesco Cescutti
Objectives
UAV - used to realize:
Photogrammetric images
Digital Surface Models (DSM) realization
3D modelling
3 principal steps:
• Flight Planning
• Photogrammetric processing
• Georeferencing
On board sensors
Equipment:
Tradizional photo cameras
Optical cameras
Thermo cameras
Multispectral Sensors
Photogrammetric surveys
Aerial photogrammetry
photogrammetry
from drones
Photogrammetric techniques
Since 90s, together with the development of the first digital cameras, Computer Vision (CV) sector took into account the automation in the orientation of multiple images.
Images sequence automatic processing 3D object spatial structure determination
“Photogrammetry includes a group of different techniques that, starting from the
photos of an object, allow to define its shape and locate it in a 3D space.”
[J.P S. Aubin, 1999]
Photogrammetric processComputer Vision techniques
integrated by the traditional and rigorous photogrammetric ones
Photogrammetry - Geometric Models
Computer Vision and Structure from
motion
Advantages:
Based on versatile softwares
Simply
Cheap (low cost hardware)
Linear mathematical models for orientation and image processing
Process automation
Scientific and commercial softwares
automatic orientation and scene and 3D objectsreconstruction from a sequence of images
Equipment
Quadricopter
Aluminium and fiber glass Frame
Ardupilot Mega 2.5.2 board
4 Brushless engines
6000 mAh Battery
GPS LEA-6h module
Turnigy 9x frSky 2.4 Ghz transmitter
Telemetry Kit for the wireless
communication between the UAV and Pc
Control board
The Ardupilot control board is based on
microcontrollers Atmel ATMEGA2560 (the same as
Arduino)
Open source firmware
Managed by Mission Planner software via
graphical interface – no programming is required
Ardupilot is an automatic and fully programmable
flight control board
Main components:
• Gyro
• Accelerometer
• Magnetometer HMC5883L-TR Digital compass
• Barometric pressure sensor for height
determination
• Mediatek MT3 329 GPS (external)
Mission planner - config/tuning
magnetometer/compasscalibration
Accelerometer calibration
Remote control calibration
ESC calibration
Engines setting
Mission Planner - Ground station
Digital camera
Disadvantages:
• Smaller sensors to respect to a reflex
• Lower quality and less stable Optics
• Internal camera parameter values are not stable
Camera Model Resolution Focal Length Pixel Size Precalibrated
Canon PowerShot A2300 (5 mm)4608 x
34565 mm
1.33578 x
1.33578 umNo
Scelta della tipologia di scatto in continuo:
• Shoot using a servomechanism
• Shoot using wireless remote control
• Shoot using an electronic intervalometerlinked to the digital camera
• Automatic shoot via software
Advantages:
• Small weight 165 g
• Cheap
• Possibility to upgrade the functionalities
CHDK
CHDK (Canon Hacking Development Kit) is a
software allowing to extend the functionalities
of some Canon digital cameras.
•A script intervalometer has been inputted
into the camera
The survey – area on the «Impossible cave» Basovizza, Trieste, Italy
Flight planning
Camera acquisition6 s
Drone speed 5 m/s
Flight height 20 m
Flight planning
Software PhotoScan Pro (Agisoft)
“structure from motion” software manages sequence of
images
Characteristics:
Polygon models creation (with texture)
Coordinate system choice
Georeferenced DEM (Digital Elevation Model) creation
Orthophoto generation
Images processing
Processing phases:
Features recognition
Matching
Orientation
Distorsions correction
Dense matching
Polygonal reconstruction
Texture mapping
Georeferencing
Features extraction - Matching - Orientation
The principal points belonging to each photo have been extracted, the photogrammetric parameters have beencalculated, the corresponding points are matched the full 3D object coordinates have been reconstructed
Dense Matching – Polygonal reconstruction
From points cloud to triangular “mesh” creation
Texture MappingOrthogonal Projection of the polygonal model
RTK GPS + GLONASS Survey – target cordinatesdetermination
in situ targetTarget printed on A4 sheet
GEOMAX zenith 10/20
Reference system and Coordinate
transformations
Target coordinates input
Accuracies
GPCEast (m) Gauss Boaga
North (m) Gauss Boaga Q/Altitude (m) E error (m) N error (m) Q error (m) Error (m)
1 2430155,702 5054402,375 366,409 -0,007049 -0,007927 -0,026614 0,029
10 2430188,349 5054429,335 365,678 0,023288 0,010777 0,004446 0,026
11 2430188,878 5054420,690 365,939 -0,014177 -0,047325 -0,015276 0,052
12 2430186,913 5054406,905 366,485 -0,005401 0,033933 -0,009185 0,035
2 2430155,523 5054410,564 366,289 -0,022018 0,003170 0,001018 0,023
3 2430152,072 5054427,498 366,626 0,020481 -0,016188 -0,006685 0,027
4 2430163,339 5054428,493 366,186 -0,011140 -0,011138 0,020783 0,026
5 2430164,699 5054417,013 366,185 0,024115 -0,011297 -0,003695 0,027
6 2430165,803 5054405,659 366,371 -0,016656 0,022460 0,020286 0,034
7 2430176,907 5054403,132 366,529 0,013537 -0,001328 0,025192 0,029
8 2430178,030 5054412,830 366,257 -0,000394 -0,018076 -0,002710 0,018
9 2430180,376 5054429,817 365,744 -0,004565 0,043034 -0,007416 0,044
Mean value 0,015583 0,023768 0,014848 0,032
Ortophoto
Ortophoto in GeoTIFF format
Orthophoto overlay on satellite images in QGIS
Export into GRD format – modelling using Surfer
Digital Elevation Model Export into TIFF format
Export into DXF format - Autocad
CONTACTS
GeoSNav Lab, Department of Engineering and Architecture,
University of Trieste, ITALY
Via Valerio 6/2 34127 TRIESTE, ITALY
Prof. Raffaela Cefalo e-mail: cefalo@dicar.units.it
Eng. Andrea Calliari e-mail: andrea.calliari@me.com
Eng. Francesco Cescutti e-mail: cescutti.francesco@gmail.com
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