Polycopters
From Vague Hope Wiki
Contents
Background reading
- http://vicacopter.com/vika1.php (via http://hackaday.com/2011/01/17/tri-rotor-helicopter-with-full-autopilot/)
- http://aeroquad.com
- Awesome t-copter http://www.rcgroups.com/forums/showthread.php?t=1314483
- Massive link dump http://www.rcgroups.com/forums/showthread.php?t=1097355
- Holy shit DO WANT http://www.youtube.com/watch?v=ozHoP_YThRI
- Tricopter build http://rcexplorer.se/projects/TriV2/TriV2.html
Hardware choices
CPU
- Android phone - free GPS/gyro/cam/Wifi, but long boot time - even with a separate watchdog, crashed phone = crashed copter. Still need to break out an interface to motor control board.
- Arduino 2009 / UNO - nice hardware as has A+D I/O built in + neat shields for motor control. GPS/gyro/cam/control method will still need to be worked out. Memory space too limited for full autonomy?
- Arduino Mega - as above, more expensive but more memory, enough for full auto?
Altitude sensor
- Barometer - least sensitive, probably best for high-flying vehicles. Needs to be kept away from the wash from the propellers.
- Ultrasound sonar - very sensitive for low-level flight, but tops out at a few metres.
- IR laser - Pete suggested this on my blog, I'd have thought performance would degrade outdoors, waiting to hear back. He's probably the expert here.
Motors & Propellers
Number-crunching needed here to figure out what kind of lift is generated by affordable components, and what that limits our chassis/hardware weight to.
Hardware required for behaviours
| Behaviours Wanted | Hardware Needed |
|---|---|
| Autopilot: takeoff, land, hover, up, down, pitch, roll, move wrt vehicle orientation | 3-axis gyro & accelerometer |
| Autopilot: move wrt north
Autonomy: local time-based behaviours (think LOGO) |
2/3 axis magnetometer |
| Autopilot: set altitude | Barometer / ground-aimed sonar / IR laser rangefinder |
| Autonomy: outdoor location-based behaviours, accuracy ~10m | GPS |
| Remove magnetometer requirement while in GPS coverage (not cost-effective) | GPS Heading Unit |
| Outdoor position accuracy ~1m | RTK GPS |
| Outdoor position accuracy ~1cm | RTCM GPS |
| Autonomy: indoor location-based behaviours, accuracy ~1m | Multi-band RF receiver capable of triangulation, plus transmitters |
| Indoor landing accuracy ~10cm | Camera with image recognition (too much code for Arduino Mega) |
| Autonomy: dynamic avoidance | Outward-aimed sonar or radar |
| Autonomy: dynamic docking | Radar |
Geekspeak
- AP/Autopilot - low-level control processing, e.g. correcting for tilt due to wind, keeping level for landing. Think "Pilot".
- Autonomy - high-level control processing, e.g. navigating to certain points, loitering. Think "Navigator".
- RF - radio frequency
- RTK / RTCM - Real Time Kinematic / something, read this: http://linux.die.net/man/5/rtcm-104 Very little chance we'll use either.
Objectives
Object 1: Platform that hovers stationary in the air.
Parts
(handy reference: http://aeroquad.com/wiki/index.php/Parts_List)
TODO: Find UK-bases suppliers for these components.
Objective 1
- Frame - balsa and ducktape? - +1 from Ian, this has got to be the easiest way to start
- Motors
- Motor controllers - Arduino shield?
- Props
- Battery
- Logic circuitry - Arduino? I already have an Arduino Mega. -はく
- sensors - at least 3-axis gyro and 3-axis accelerometer?
