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Stanford APM:Plane Overview Trent Lukaczyk April 7, 2014 AA241X – UAV Design and Build 1.

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Presentation on theme: "Stanford APM:Plane Overview Trent Lukaczyk April 7, 2014 AA241X – UAV Design and Build 1."— Presentation transcript:

1 Stanford APM:Plane Overview Trent Lukaczyk April 7, 2014 AA241X – UAV Design and Build 1

2 The Problem Fly Autonomously Airframe Construction State Estimation Algorithm Processing Control Actuation Ground Monitoring 2

3 The Components Autopilot Unit Wireless Telemetry Remote Control Radio GPS Radio Compass Magnetometer Airspeed Sensor Battery Monitor Servos, ESC, Motor 3

4 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 often) Needs: to point forward to be securely attached accelerometer calibration if relocated 4

5 Wireless Telemetry 915 MHz, 100mW Shares a “NetID” “MAVLink Protocol” 5

6 Wireless Telemetry 6 USB Micro B USB A DF13 6-Pin DF13 5-Pin

7 DF13 Connectors 7 Pain and a Half to use Easy to break But small, reconfigurable Be careful when disconnecting! Can shave these hooks off with a knife Can add hot glue at the wire-connector joint. Do not use super glue here. Lift this lip gently with a screwdriver

8 Radio Control Setup RC Transmitter, 2.4 GHz “Binds” with Receiver – Always carry the bind plug Four axes + mode switch Turn on first, before plane 8 Autopilot Mode Switch

9 Radio Control 9 3pin Servo Wires x5

10 Radio Control Setup 10 Autopilot Mode Switch The order of these vary with receiver

11 Servo Wires Mixing up signal and ground can fry electronics Look for markings like this - 11

12 GPS + Compass 1.57 GHz GPS radio – 5Hz position update – Needs clear sight of sky Magnetometer – Provides heading estimate – Needs to be clear of high-current electronics – Needs: to point forward calibration if relocated 12

13 13 DF13 6pin GPS DF13 5pin DF13 4pin MAG DF13 4pin Remember to point GPS and APM forward

14 Airspeed Sensor Pitot tube measures difference in “Static” and “Total” pressure, which is related to airspeed. Airspeed is relative to wind – will be higher or lower if you travel against or with the wind 14

15 Airspeed Sensor 15 Silcone Tubing 3pin Servo Wire A1

16 Power Module Records current and voltage from battery Integrate for energy usage, and battery level Powers APM, Receiver, Radios, and Servos 16

17 Lithium Polymer Batteries 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

18 LiPo Discharge LiPo’s die suddenly around 3.4Volts/Cell Be ready to land around 3.5Volt/Cell 18 traxxas.com Higher Current

19 Speed Controller Rated by Max Current and Max Voltage Direct Current Power in, Three-phase Alternating Current out “Opto” vs “BEC” – BEC can power RC gear, Opto can’t 19

20 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

21 Power Electronics Setup 21 DC Power 3 Phase AC DF13 6-Pin

22 Carbon Folding Props More rigid, more efficient, more expensive (vs plastic props) More dangerous – they are spinning knives Spinner cap lets them fold on landing, or if motor braking is on (more efficient glide) 22

23 Servos Drive Motor + Rotation Sensor + PID Control board … in 8-grams Forcing the control arms by hand wrecks gears 23

24 Servo Setup 24 Ailerons Elevator Rudder Throttle Servo Wire “Y” 3pin Servo Wires

25 The Components Autopilot Unit Wireless Telemetry Remote Control Radio GPS Radio Compass Magnetometer Airspeed Sensor Battery Monitor Servos, ESC, Motor 25

26 The Problem Fly Autonomously Airframe Construction State Estimation Algorithm Processing Control Actuation Ground Monitoring 26

27 Stanford_ArduPlane An easy embedded flight control software for Aerospace Engineers, based on ArduPlane ArduPlane code without the control law https://github.com/rbunge/Stanford_ArduPlane 27

28 Development Tools Download and install the ArduPilot Arduino IDE Download Libraries and place in the Arduino sketch folder Download Stanford ArduPlane 28

29 Building Open \Stanford_ArduPlane\ \Stanford_ArduPlane.ino with Arduino Check the board type (Mega 2560) and COM port “Verify” = compile “Upload” = compile and upload to APM 29

30 The Code Editable: – AA241X_ControlLaw.ino – AA241X_ControlLaw.h Not Editable: – AA241X_Competition.h – AA241X_aux.ino – AA241X_aux.h – Everything Else… 30

31 The Code State and Control Variables (AA241X_aux.h) – Roll, pitch, yaw angles and rates – Inertial velocity and accelerations – Heading – Airspeed – GPS X-Y positions – GPS and Barometric Altitudes – Battery Consumption – RC Inputs, Servo + Throttle Outputs 31

32 The Control Loops AA241X_ControlLaw.ino – AA241X_AUTO_FastLoop(void){} ~50Hz – AA241X_AUTO_MediumLoop(void){} ~10 Hz – AA241X_AUTO_SlowLoop(void){} ~3.3 Hz Distribute algorithm to use CPU cycles wisely Beware of APM Memory limits – 256k Flash Program Memory, 8K SRAM, 4K EEPROM 32

33 The Camera Function AA241X_aux.h 33

34 Telemetry Plotting 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 34

35 The Problem Fly Autonomously Airframe Construction State Estimation Algorithm Processing Control Actuation Ground Monitoring 35

36 Resources FliteTest: youtube channel DIY Drones: forum RC groups: forum GrabCAD: community CAD models 3DRobotics: Store and Manuals GitHub: Stanford_ArduPlane Code 36


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