UAS110 Intro to UAV Systems5: UAS Components
10/27/2019
1
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
UAS110 Intro to UAV Systems5: UAS Components
10/27/2019
2
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
UAS110 Intro to UAV Systems5: UAS Components
10/27/2019
3
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
UAS110 UAS Components 6
UAS110 Intro to UAV Systems5: UAS Components
10/27/2019
4
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
UAS110 UAS Components 8
UAS110 Intro to UAV Systems5: UAS Components
10/27/2019
5
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
UAS110 UAS Components 9
Multirotor configurations
there are number of motor/prop configurations available for multirotors
ex: quadrotors may have either 'x' or '+' orientation
UAS110 UAS Components 10
UAS110 Intro to UAV Systems5: UAS Components
10/27/2019
6
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
UAS110 UAS Components 11
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
UAS110 UAS Components 12
UAS110 Intro to UAV Systems5: UAS Components
10/27/2019
7
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)
UAS110 UAS Components 13
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
UAS110 UAS Components 14
UAS110 Intro to UAV Systems5: UAS Components
10/27/2019
8
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
UAS110 UAS Components 15
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
UAS110 UAS Components 16
Youtube Animations:How 2 Stroke Engine WorksTwo-stroke engine - How it works
UAS110 Intro to UAV Systems5: UAS Components
10/27/2019
9
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
UAS110 UAS Components 17
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
UAS110 UAS Components 18
UAS110 Intro to UAV Systems5: UAS Components
10/27/2019
10
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
UAS110 UAS Components 19
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"
UAS110 UAS Components 20
UAS110 Intro to UAV Systems5: UAS Components
10/27/2019
11
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…
UAS110 UAS Components 21
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
UAS110 UAS Components 22
UAS110 Intro to UAV Systems5: UAS Components
10/27/2019
12
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
UAS110 UAS Components 23
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
UAS110 UAS Components 24
UAS110 Intro to UAV Systems5: UAS Components
10/27/2019
13
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
UAS110 UAS Components 25
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
UAS110 UAS Components 26
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
UAS110 Intro to UAV Systems5: UAS Components
10/27/2019
14
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)
UAS110 UAS Components 27
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.
UAS110 UAS Components 28
UAS110 Intro to UAV Systems5: UAS Components
10/27/2019
15
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
UAS110 UAS Components 29
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?
UAS110 UAS Components 30
UAS110 Intro to UAV Systems5: UAS Components
10/27/2019
16
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)
UAS110 UAS Components 31
Battery Connectors
UAS110 UAS Components 32
UAS110 Intro to UAV Systems5: UAS Components
10/27/2019
17
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
UAS110 UAS Components 33
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
UAS110 UAS Components 34
UAS110 Intro to UAV Systems5: UAS Components
10/27/2019
18
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
UAS110 UAS Components 36
UAS110 Intro to UAV Systems5: UAS Components
10/27/2019
19
Tx Operation Modes
UAS110 UAS Components 37
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
UAS110 UAS Components 38
UAS110 Intro to UAV Systems5: UAS Components
10/27/2019
20
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
UAS110 UAS Components 39
Servo Specifications
ex: Futaba S9452 Digital High-Torque High-Speed
UAS110 UAS Components 40
CM=Coreless Motor, 2BB=2 Ball Bearings, MG=Metal Gear, WP=Water Protected
UAS110 Intro to UAV Systems5: UAS Components
10/27/2019
21
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!
UAS110 UAS Components 41
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.
UAS110 UAS Components 42
UAS110 Intro to UAV Systems5: UAS Components
10/27/2019
22
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
UAS110 UAS Components 43
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
UAS110 UAS Components 44
UAS110 Intro to UAV Systems5: UAS Components
10/27/2019
23
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
UAS110 UAS Components 45
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
UAS110 UAS Components 46
UAS110 Intro to UAV Systems5: UAS Components
10/27/2019
24
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
UAS110 UAS Components 47
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
UAS110 UAS Components 48
UAS110 Intro to UAV Systems5: UAS Components
10/27/2019
25
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
UAS110 Intro to UAV Systems5: UAS Components
10/27/2019
26
Ex: DJI GO4 Display
UAS110 UAS Components 51
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
UAS110 UAS Components 52
UAS110 Intro to UAV Systems5: UAS Components
10/27/2019
27
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
UAS110 UAS Components 53
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
UAS110 UAS Components 54