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Autonomous Photography Aircraft

This project focuses on the design and development of an autonomous photography aircraft. Its uses include government reconnaissance, search and rescue, commercial mapping, real estate, and artistic photography. The goal is for the aircraft to take off, fly to target coordinates, take photos, return to landing coordinates, and land.

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Autonomous Photography Aircraft

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  1. Autonomous Photography Aircraft Group 18 Chris Hansen & Mark Inderhees ECE 445 Senior Design December 1, 2005

  2. Introduction – Uses • Government • Reconnaissance • Search and Rescue • Commercial • Mapping • Real Estate • Artistic Photography

  3. Introduction – Goal • Takeoff • Fly to target coordinates • Take photos • Return to landing coordinates • Land

  4. Overview – Components • Power Supply • dsPIC – control processing, CPU • GPS – location • Compass – heading • Accelerometer – pitch & roll • Video & Text Overlay – feedback • RS232 – debugging • Servo control – mechanical control

  5. Overview – Components

  6. Overview – Original Design

  7. Overview – Final Design

  8. Design – Power • Latching ON/OFF with self shut-down • First attempt with MAX5035 • Servo and logic power are seperate • Second attempt with TPS40190 • Plug-in Power module • Powers both servos and logic • Problems with high frequency ringing • Scope measurements

  9. Design – Power

  10. Design – Power

  11. Design – Power - Testing

  12. Design – dsPIC • Microchip’s dsPIC30F6014A • Used because fast, many peripherals, advanced 16 bit architecture and ISA • CPU: ties all components together • Logic for mechanical control • Interrupt priority levels • Aligned code

  13. Design – dsPIC

  14. Design – dsPIC – PID • Proportional Integral Derivative (PID) • Error = Actual – Target (used in P,I,D) • Servo = P+I+D • Nested PID’s for Heading and Roll/Pitch • Test: Target Pitch & Roll = 0 • Plane servos/ailerons response

  15. Design – GPS • Garmin GPS 18 5Hz • Fast updates: 40mph, 1 update per 12ft • Universal output in NMEA 0183 • Latitude, Longitude, Velocity, Heading, Altitude (Satellites, Quality, Magnetic Declination) • String processing, < 5% CPU

  16. Design – GPS – Calculations • Target Heading, depends on quadrant • Heading = arctan(ΔLong/ΔLat) • Quad 1 same, 2 add 360°, 3or4 add 180° • Target Roll = ΔHeading * -.5 • Target Pitch = arctan(ΔAlt/2D Distance) • Approximate Target Distance = √(Long^2+Lat^2+Alt^2) • Test “Are we close to Target”

  17. Design – GPS – Testing • Heading & Pitch: target as apartment, drove around campus • Roll: while driving, made sure roll was changing with ΔHeading • Distance: set target coordinates to current location, resulted in distance of ±5m

  18. Design – GPS – Testing

  19. Design – Accelerometer • Freescale A7260 3-axis Accelerometer • Force in x, y, z values • RC filtering • Average value over 20ms • Calibrate

  20. Design – Accelerometer – Calc

  21. Design – Accelerometer – Calc • Force from Gravity = √(x^2+y^2+z^2) • Actual Pitch = -arcsin(x/G) • Actual Roll = arcsin(y/ (G*cos(Pitch))

  22. Design – Accelerometer – Test • Tilt board, measure with protractor • Measurements are extremely accurate • Problems with vibrations • Problem when flying, acceleration of plane • Subtract centripetal acceleration ~K*V^2/r

  23. Design – Compass • PNI 3-Axis Magneto-Inductive Compass (MicroMag3) • Outputs 3 16bit integers (x, y, z) via SPI • Problems, outside fields (circuits, motor)

  24. Design – Compass – Calc • Earth Magnetic Field runs N to S, • Actual Heading is Quadrant dependent • Heading = arctan(Cy/Cx) • Quad 1 same, 2 add 360°, 3or4 add 180° • But compass needs to be compensated for aircraft tilt • Somewhat complicated trig equations to account for aircraft tilt • Functions written, but untested

  25. Design – Compass – Testing • Easy to find N in Urbana-Champaign • Problems • Magnetic field in room • Magnetic field from circuit, motor • Place compass far away in wing • Really needs integrated calibration routine

  26. Design – Video & Text Overlay • Began previous semester • Added I2C • Added text black and white control • Video muxing between two cameras

  27. Design – Video & Text Overlay

  28. Design – Video & Text Overlay

  29. Design – RS232 • dsPIC UART module, MAX3223 • Used when debugging • Can see large amount of data • Compatible with HyperTerminal or “RS232 Receiver” • Reusable for other projects

  30. Design – Servo Control • Need ability to switch between manual and autonomous control • Time incoming pulses using Cn interupts and timers • Output either same pulse or our own calculated from PID • Use WDT to determine if incoming servo data is good

  31. Design – Servo Control – Test • Measure incoming and outgoing pulse length with oscilloscope • Problems with servo glitching • Solution: servo code has highest priority

  32. Fabrication – Circuit • Double layer circuit boards constructed using photo process • Can do 7mil traces and spaces • Special attention paid to power buses • Designed with Cadsoft Eagle

  33. Fabrication – Circuit

  34. Fabrication – Airplane • Used old airplane from last semester • Not large enough to fit all circuitry • Damaged during windy flight testing  • New plane under construction • Can house all circuitry including digital camera

  35. Fabrication – Airplane

  36. Video Power Kit

  37. Flight Testing

  38. Flight Testing • Promising, could stay stable in high winds for short time. • Need many more flights to calibrate PID and Accelerometer

  39. Recommendations • Much more flight testing • Heavier, Larger Airplane (not complete) • Add 3-axis gyro for complete 6 degree of freedom motion sensing • Don’t fly in high winds • Do not need compass, use only GPS • Use Kalman filter to determine orientation/position

  40. Credits • Melvin Lathara – roommate C Guru

  41. Thank You

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