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The Problem
Fly Autonomously Airframe Construc@on
State Es@ma@on
Algorithm Processing
Control Actua@on
Ground Monitoring
2
The Components
• Autopilot Unit • Wireless Telemetry
• Remote Control Radio
• GPS Radio • Compass Magnetometer
• Airspeed Sensor • BaKery Monitor
• Servos, ESC, Motor
3
Autopilot Unit
• Auto Pilot Module (APM) • ArduPilot Mega (APM) 2.6 • Based on Arduino • 16MHz Atmega2560 processor • 16 MB dataflash memory
~ 2hours of logging (download oWen)
• Needs: to point forward to be securely aKached accelerometer calibra@on if relocated
4
DF13 Connectors
7
• Pain and a Half to use • Easy to break • But small, reconfigurable
• Be careful when disconnec@ng!
Can shave these hooks off with a knife
Can add hot glue at the wire-‐connector joint.
Do not use super glue here.
LiC this lip gently with a screwdriver
Radio Control Setup
• RC TransmiKer, 2.4 GHz • “Binds” with Receiver – Always carry the bind plug
• Four axes + mode switch
• Turn on first, before plane
8
Autopilot Mode Switch
GPS + Compass
• 1.57 GHz GPS radio – 5Hz posi@on update – Needs clear sight of sky
• Magnetometer – Provides heading es@mate – Needs to be clear of high-‐current electronics
– Needs: to point forward calibra@on if relocated
12
GPS and Compass
13
DF13 6pin GPS DF13 5pin
DF13 4pin MAG DF13 4pin
Remember to point GPS and APM forward
Airspeed Sensor
• Pitot tube measures difference in “Sta@c” and “Total” pressure, which is related to airspeed.
• Airspeed is rela@ve to wind – will be higher or lower if you travel against or with the wind
14
Power Module
• Records current and voltage from baKery • Integrate for energy usage, and baKery level • Powers APM, Receiver, Radios, and Servos
16
Lithium Polymer BaKeries
• 3.7 Volts per Cell • Metrics: – N-‐Cells (2S = 2 Cells = 7.4V) – Capacity (C = 1100 mAh) – Discharge Rate (25C = 27.5A) – Charge Rate (2C = 2.2A)
• Can catch fire or leak during charging – Always be present during charging
• Capacity loss or Bricking if over-‐discharged – i.e. leaving plugged in over night
17
LiPo Discharge
• LiPo’s die suddenly around 3.4Volts/Cell • Be ready to land around 3.5Volt/Cell
18 traxxas.com
Higher Current
Speed Controller
• Rated by Max Current and Max Voltage • Direct Current Power in, Three-‐phase Alterna@ng Current out
• “Opto” vs “BEC” – BEC can power RC gear, Opto can’t
19
Brushless Outrunner Motor
• “Outrunner” -‐ magnets rotate around stator • Rated by kV = no load rpm/V – High kV = fast rpm, low torque
– Low kV = low rpm, high torque
• Too much power melts windings, burns out motor
20
Carbon Folding Props
• More rigid, more efficient, more expensive (vs plas@c props)
• More dangerous – they are spinning knives
• Spinner cap lets them fold on landing, or if motor braking is on (more efficient glide)
22
Servos
• Drive Motor + Rota@on Sensor + PID Control board … in 8-‐grams
• Forcing the control arms by hand wrecks gears
23
www.twf8.ws
The Components
• Autopilot Unit • Wireless Telemetry
• Remote Control Radio
• GPS Radio • Compass Magnetometer
• Airspeed Sensor • BaKery Monitor
• Servos, ESC, Motor
25
Telemetry Ploqng
• Two types of logs – Telemetry log
– Dataflash log • store at higher log-‐rates • Download from APM over USB Cable
• Mission Planner can dump matlab data files
26
The Problem
Fly Autonomously Airframe Construc@on
State Es@ma@on
Algorithm Processing
Control Actua@on
Ground Monitoring
27