UAS110 Intro to Unmanned Aerial Systemsaet.calu.edu/~jsumey/UAS110/N5-UAScomponents.pdf · UAS110 Intro to UAV Systems 5: UAS Components 10/27/2019 3 Airframes: Fixed Wing aka aeroplane,

UAS110 Intro to UAV Systems5: UAS Components

10/27/2019

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UAS110 Intro to Unmanned Aerial Systems

5: UAS Components© 2019 J. Sumey

California University of PA

rev. 9/17/19

Overview

components of a UAS basically include: platform / airframe propulsion communications (ground-, air-data terminal) on-board flight control payload launch / recovery system ground control station

we now explore these in detail

UAS110 UAS Components 2


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UAV Airframes

may be broadly grouped as: aerostats: a lighter-than-air craft that gains its lift through the

use of a buoyant gas†

airships

aerodynes: a heavier-than-air craft that derives lift from dynamic motion through the air fixed "conventional" wing rotary wing / rotorcraft ornithopter – produces thrust via flapping wings

UAS110 UAS Components 3† en.wikipedia.org/wiki/Aircraft

Airframes: Aerostats

i.e. unpowered balloons & powered airships airship: any powered, steerable aircraft inflated with a lighter-than-air

gas (hydrogen, helium, hot air)

dirigible: synonym for airship

blimp: a non-rigid airship whose shape is maintained by internal gas pressure

zeppelin: a rigid airship made by the Luftschiffbau Zeppelin company of Germany

UAS110 UAS Components 4† en.wikipedia.org/wiki/Aerostat


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Airframes: Fixed Wing

aka aeroplane, airplane, plane the lifting wing does not move relative to the fuselage (body) lift is created when moving through air via Bernoulli's principle (next slide)

use of driven propeller(s) to provide forward thrust wing configuration†

number of wings: monoplane, biplane, multiplane placement: low wing, mid wing, shoulder wing, high wing, parasol planform: tapered, delta, sweep and others

UAS110 UAS Components 5† en.wikipedia.org/wiki/Wing_configuration

Bernoulli's Principle

Daniel Bernoulli, Swiss mathematician & physicist, in 1738: an increase in air speed causes an inversely proportional drop in pressure

(and vice-versa)

an important principle in fluid dynamics



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Airframes: Rotary Wing†

def: a heavier-than-air craft that uses lift created by rotary wings (rotor blades) that revolve around a mast helicopter: 1 or more rotors that are powered for duration of flight autogyro: use unpowered rotor and engine-powered propeller for

thrust

rotor configuration number of blades: 2-6 per mast number of rotors: tandem, coaxial, intermesh quadrotor / quadcopter / quads multirotors – tricopter, hexacopter, octocopter

UAS110 UAS Components 7† en.wikipedia.org/wiki/Rotorcraft

Airframes: Quad/Multirotors

except for tricopters, multirotors use an equal number of fixed mount CW and CCW motors tricopters use 2 fixed

rotors plus 1 tiltable

6 degrees of freedom:3 rotational, 3 translational

lift, tilt, rotation are controlled by varying speed of motors



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Quadrotor Control

Motor changes/results

M1+,M2+,M3+,M4+ z+

M1-,M2-,M3-,M4- z-

M3+,M1- ωy+ x+

M3-,M1+ ωy- x-

M4-,M2+ ωx+ y+

M4+,M2- ωx- y-

M1+,M3+,M2-,M4- ωz+ CW

M1-,M3-,M2+,M4+ ωz- CCW


Multirotor configurations

there are number of motor/prop configurations available for multirotors

ex: quadrotors may have either 'x' or '+' orientation



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Propulsion

self-powered UAVs use some form of propulsion to create lift either directly (rotary wing) or indirectly (fixed wing) via propeller or jet blast

propellers/rotors may be driven directly or via gear reduction depending on RPM range of power source


Propulsion: Types of Power Sources

internal combustion engines reciprocating (piston)

4-cycle 2-cycle

rotary

turbines electric motors

Note: engines burn some fuel type via combustion while motorsuse electric power



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Propulsion: Fuels

gasoline (4-stroke)

gas/oil mix (2-stroke)

kerosene, aka jet fuel (turbines)

nitromethane, aka "glow fuel" (smaller model engines) Methanol + Nitromethane (0-30%) + oil

batteries (motors)


Reciprocating Engines

have 1 or more cylinders each containing a piston driven by fuel

combustion which drives a connecting rod to convert linear motion to rotary motion

which drives a crankshaft providing rotational torque

which drives propeller or rotor either directly or via gear/belt drive train



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Engines: 4-stroke

2 rotations per complete cycle1. intake/induction: inflow of air/fuel mixture2. compression: of the mixture3. combustion: ignition/burn of the mixture,

causes rapid volume expansion4. exhaust: expulsion of burnt residue

air- or liquid-cooled well understood, efficient, reliable high vibrations due to large difference between peak

(during power stroke) and mean torque


Youtube Animations:4 Stroke Engine AnimationFour Stroke Engine How it Works

Engines: 2-stroke

1 rotation per complete cycle combines intake & compression on

upstroke, power & exhaust on downstroke

requires precise port location

does not require valves, etc. much simpler & lighter!

less vibration than 4-stroke but poorer performance at low RPM/loading


Youtube Animations:How 2 Stroke Engine WorksTwo-stroke engine - How it works


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Propulsion: Gas Engines

gasoline engines use spark ignition via magneto or electronic ignition module

available in 1, 2, 4 cylinders

uses gas/oil mix

ex: Duratrax 23cc gas w/ pull-start

ex: DLE 60cc twin gas w/ electronicignition & mufflers


Propulsion: Glow Engines

"glow" fuel engines use nitromethane (model) fuel and a glow plug platinum coating causes catalytic effect

available in 4-cycle and 2-cycle (more popular), generally single cylinder

sizes range from 0.10 to 1.60 cu in

ex: OS .95AX ringedengine w/ muffler



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Propulsion: Rotary Engines

reduces vibration by eliminating reciprocating motion

based on rotation of a 3-sided geometrical rotor within a 2-lobed geometrical stator

each face of the rotor completes all 4 phases during each rotation intake, compression, combustion, exhaust

was used in Sikorsky Cypher


Youtube Animation:Rotary Engine

Propulsion: Turbines

just as with full-scale jets, UAVs can also be powered by turbine engines

uses kerosene & jet A

high RPM, lowest vibration, efficientat high altitudes but also high costs

"Jet Engine: How it works?"

"The model jet engine"



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Propulsion: Electric Motors

electric motors have become very popular for many types of UAV platforms

advantages: clean, quiet, smaller, constant torque

however: need battery power, sometimes A LOT

types…

specs…


Motor Types: Brushed DC

simple, 2 wires rotation based on magnetic field in the windings of the armature and

magnets with particular N/S orientation magnetic field is switched each rotation via brushes and commutator polarity determines rotation direction,

volts determines rotational speed (RPM) brushes subject to wear to point of failure,

large source of EMI (noise) 75-80% efficient

animation https://en.wikipedia.org/wiki/Brushed_DC_electric_motor

sample motors http://www.robotshop.com/en/dc-motors.html



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Motor Types: Brushless DC

more complex, 3 wires no brushes, 85-90% efficient! based on moving magnetic field among stator coils and fixed

magnets in rotor requires complex 3-phase drive signals from an

electronic speed controller (ESC) classified as outrunners and inrunners

animation https://www.youtube.com/watch?v=bCEiOnuODac

sample motors http://www3.towerhobbies.com/cgi-

bin/wti0093p?&C=GHG&D=Motors-R/C---Brushless---Aircraft


BLDC Motor Specs

size (in mm) & kV ex 1: Great Planes Rimfire 50cc motor is 80-75-230

meaing: rotor diameter = 80mm, rotor height = 75mm, and its RPM = 230 per volt

operating with a 44V battery yields 44Vx230RPM/V = 10,120 RPM

ex 2: Great Planes Ammo 28-45-3600kV rotor diameter = 28mm, rotor height = 45mm, and

RPM = 3600 per volt operating with a 16V battery yields 16Vx3600RPM/V = 57,600 RPM

other specs load / no-load current, burst current, mounting method, prop

ranges



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Electronic Speed Control (ESC)

an electronic, microprocessor-based unit used between a DC motor and power source to control the motor's rotational direction and speed also inputs throttle command from receiver or flight controller

may or may not have "Battery Eliminator Circuit" (BEC) to power electronic flight components

is called "BEC" because it eliminates the need for a separate flight/receiver battery

available in both brushed and brushless (more popular) rated in terms of continuous/burst Amps and maximum

voltage sample ESCs

http://www.castlecreations.com/en


Electricity 101: The Basics

Volts: amount of electric potential ("pressure") on a circuit; symbol: V, units: V

Amps: amount of current flowing through a circuit; symbol: I, units: A

Resistance: amount of restriction on current through a circuit; symbol: R, units: Ω


Power (Watts, W) = V * I ex: a light bulb operating at 100V and 0.75A consumes 75W of power

Ohm's Law: R = V / I ex: a 12V motor with 24Ω of resistance will consume 0.5A of current


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Electricity 101: Cells and Batteries

electric potential can be stored in cells, measured in volts a cell also has a certain total charge (C), measured in A or mA usually the charge is expressed in a unit of time, i.e. Ah, Wh

multiple cells may be connected together to form batteries yielding increased voltage (cells in series) and/or increased current (cells

in parallel) configuration notation: nSmP (S=serial, P=parallel), ex: 3S, 2S2P, etc.

2 types of cells based on manufacturing materials & process primary – single use, charge "installed" during manufacturing, ex: alkaline secondary – many cycles via recharging (our main interest)


Electricity 101: Cells and Batteries

batteries also have charge/discharge ratings i.e. 2C charge, 30C discharge

this factor is multiplied by the total charge of battery to determine maximum safe charge and discharge rates

ex: a 2100mA/2C/30C battery may be safely charged at 4.2A and discharged at 63A

different chemistries provide different characteristics weight, size, form factor, charge/discharge rates, cycles, usable

temperature range, etc.



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UAV Battery Chemistries

Nickle Cadmium (NiCd): 1.2V/cell (nominal) older technology, moderate weight, temp stable, low cost, 150 W/kg, 10%/month

self discharge cadmium is environmental hazard

Nickel Metal-Hydride (NiMH): 1.2V/cell slightly heavier, temp stable, low cost, 250-1000 W/kg, 3%/month

Lithium Ion (LiIon): 3.6V/cell slightly heavy, 250-350 W/kg, 8%/month

Lithium Polymer (LiPo): Vnom=3.7V/cell, Vmax=4.2V/cell light weight, most flexible form factor, 250-350 W/kg, 2%/6 months, fire hazard

Lithium Iron Phosphate (LiFePO4, aka "LiFe"): 3.2V/cell 200 W/kg, 2%/6 months, >10 year life


Additional Battery Details Wires

battery leads are sized (in AWG) according to max discharge rate Connectors

connector sizing must match load current requirements and wire size used Cell balance

Lithium-based battery performance strongly dependent on charge balance between cells balanced charging is preferred to maintain long battery life

using balance tap and lithium-compatible smart charger use storage mode (60-70% charge) when not used for a while

Chargers must always use proper charger type / settings for each

particular chemistry! incorrect charger settings are the #1 cause of battery fires

especially with lithium-based batteries 15 Things Every LiPo Battery User Should Know How Fast can a LiPo Catch Fire?



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Battery Chargers

modern charger features: AC/DC input

multiport (1,2,4 outputs)

multiple chemistries

charge/discharge/storage modes

battery profile memory

ex: Hitec AC Plus voice prompting

Bluetooth control/monitoring

charger setup:1. select chemistry

2. select charge mode

3. select cells / pack voltage

4. select charge rate (current)


Battery Connectors



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Propellers

are used in fixed-wing aircraft and multirotors aka "airscrews" driven by the engine(s)/motor(s) to produce

thrust directly and lift indirectly may be either tractor (ahead of power source) or pusher (behind) may also be in the form of a ducted fan in jet aircraft

made of wood, nylon, ABS plastic, composite available with 2-, 3-, 4-blades, etc. labeled as "d x p" where d=diameter, p=pitch


Communications

many UASs use state-of-the-art radio links to connect the GCS (pilot) to the UAV uplink for command & control (CC)

downlink for telemetry, etc.

modern radio systems as used in the R/C hobby are popular developed & refined over many years

use 2.4 GHz (ISM band in the microwave region) with frequency hopping / spread spectrum are highly reliable



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UAS110 UAS Components 35image from http://www2.lbl.gov/MicroWorlds/ALSTool/EMSpec

Q: where is 2.4 GHz ISM band?

UAS Radio Components: Tx

Ground side: transmitter / rc controller function: to input various switch and variable

inputs from pilot, convert to a digital data stream, and send wirelessly to rx.

handheld, battery-powered generally rechargeable

provides multiple channels via 2 primary joysticks plus additional switches/sliders/knobs from 6 (low end) to 16 or more (high end) channels minimum requirements: pitch, roll, yaw, throttle additional channels: gear, flaps, beeper, lights, flight mode, camera controls, etc.

may feature LED indicators, LCD screen, audio output, haptic feedback example manufacturers: Futaba, Spectrum, Graupner, Jetti, Frsky



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Tx Operation Modes


describes the function assigned to each joystick axis

mode 2 is most common (USA)

mode 1 is more European modes 3,4 rarely used some transmitters are

user-configurable

UAS Radio Components: Rx

UAV side: receiver, battery, servos (fixed wing, helicopter), flight controller (multirotors) function: to receive and decode wireless digital data stream from tx then

output separated channel data to individual channel output ports, which normally go to servos channel position is represented as a periodic pulse with a width 1~2 ms.

some modern receivers may provide combined channel data in packet form on a single output port in addition to or in lieu of separate channel outputs ex: SBUS (Futaba), XBUS (Spectrum), SUMD (Graupner)

tx/rx pair is generally manufacturer-specific and are not interchangeable



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Servos

an example actuator, converts electronic signal to mechanical motion linear or rotational (more common) consists of motor, gear train, feedback mechanism (potentiometer), and control

electronics types: analog – older, slower, lower cost, no processor digital – newer, more variety, faster, more precise, internal MCU

sizes: micro, mini, standard, large/specialty ratings: operating voltage, typ. 5V, 6V, 8.4V (HV) speed, ms. per 60° rotation torque, in oz-in


Servo Specifications

ex: Futaba S9452 Digital High-Torque High-Speed


CM=Coreless Motor, 2BB=2 Ball Bearings, MG=Metal Gear, WP=Water Protected


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Servo Connection

r/c type servos use 3 wire connection: Gnd, V+, Signal wiring & connector standards: Futaba, JR,

Hitec (Airtronics no longer used)

servo normally plugs into one channel on the rx or an output channel of a flight controller

can also use a 'Y' cable; ex: flaps

note polarization!


Servo Operation

‘Signal' is a positive 1~2 ms. pulse which determines output position frame is repeated every 50 (analog) to

300 (digital) Hz some servos may be "overdriven" to

900~2100 us

servo output variations 120°, 180°, continuous (robotic

applications) splined output shaft can drive a wheel,

arm, etc.



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On-board Flight Control

refers to a UAV component that adds automatic flight control capabilities ex: flight stabilization, altitude hold, GPS-

based flight plan, auto take-off/landing, return-to-home/launch (RTH/RTL)

optional on fixed- and rotary-wing types, required on multirotors

sits between receiver and flight control actuators ex: EAGLE A3 6-axis RC Flight Control

System for Airplane


Flight Control: Fixed Wing

Flex Innovations Aura 8 advanced flight control system www.flexinnovations.com

EagleTree Guardian 2D/3D Stabilizer www.eagletreesystems.com

EagleTree Vector Flight Controller actually supports fixed wing & multirotors



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Flight Control: Rotary Wing

specifically designed for helicopter applications

ex: Futaba CGY750 3-axis flybarless controller www.futabarc.com

Mikado VBAR NEO www.mikadousa.com


Flight Control: Multirotor

designed to control multiple motor/prop stacks

a range of low-cost FCBs derived from the "MultiWii" project ex: CC3D, Flip32, Naze, Lux, SPracing, etc.

hobbyking.com

seriouslypro.com

professional-grade flight controllers ex: DJI A3, N3, Naza series, Pixhawk



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Combined Flight Controller / Rx

some manufacturers offer a receiver and flight controller integrated into a single unit

ex: Spektrum DSMX Flybarless Control System www.horizonhobby.com

Graupner 2.4 GHz Flight Controllers www.graupnerusa.com


Telemetry

refers to downlink of pertinent aircraft conditions/status from UAV to ground

may be overlaid on video signal and/or map (FPV modes) telemetry data battery charge state – via voltage sensor battery consumption – via current sensor flight mode/settings confirmation location/distance from GCS – via GPS altitude/vertical speed – via GPS or barometric pressure (BP) sensor attitude – via gyro sensors



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Ex: MinimOSD Display

UAS110 UAS Components 49https://github.com/diydrones/MinimOSD-Extra/wiki

Ex: EagleTree Vector OSD

UAS110 UAS Components 50RCgroups OSD article w/ video


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Ex: DJI GO4 Display


Payload

the payload is anything added to a UAV not actually required for flight / flight control

typically defines the mission of the UAV

most common payload ex: camera

pan-tilt mounts are sometimes used may be servo controlled

or self-stabilized via a camera gimbal



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Payload: Gimbals

gimbal: an autonomous component that self-stabilizes its mounted payload, typically a camera has dedicated microprocessor-based controller,

gyro sensors (for tilt angle), and high-precisionbrushless DC motors

available in 2-axis (TR) and 3-axis (PTR) forms powered from UAV's or independent battery may accept "servo" input channels for manual

control ex. gimbals: hobbyking.com


References

1. "Airships, Dirigibles, Zeppelins, & Blimps: What’s the Difference?", www.airships.net/dirigible

2. "Aerial Robotics: Quadrotors", UofPA, www.coursera.org/learn/robotics-flight/lecture/XguwZ/quadrotors

3. www.animatedengines.com, © Matt Keveney

4. "How Electric Motors Work", Stefan Vorkoetter, http://www.stefanv.com/rcstuff/qf200212.html

5. "How Do Servo Motors Work", Frances Reed, www.jameco.com


Documents

UAS110 Intro to Unmanned Aerial Systemsaet.calu.edu/~jsumey/UAS110/N5-UAScomponents.pdf · UAS110 Intro to UAV Systems 5: UAS Components 10/27/2019 3 Airframes: Fixed Wing aka aeroplane,