Autonomous Photography Aircraft

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