introduction to uav (unmanned aerial vehicle)

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