Here's what it is:
A custom PCB with an embedded processor (ATMega168) combined with circuitry to switch between RC control and autopilot control (that's the multiplexer/failsafe, otherwise known as a "MUX"). This controls navigation (following GPS waypoints) and altitude by controlling the rudder and throttle. These components are all open source. This autopilot is fully programmable and can have any number of GPS waypoints (including altitude) and trigger camera or other sensors
As with the Basic Stamp autopilot, to make a fully autonomous aircraft you need to combine this navigation autopillot with a stabilization system, for which we turn to our old friend, the FMA Co-Pilot (off-the-shelf infrared sensors and control board to keep the plane flying level), which controls the ailerons and elevator.
By using Jordi's MUX, which allows us to switch from autopilot to manual RC control in hardware, we gain several advantages over the Basic Stamp:
1) Because the switching isn't handled by the processors, we don’t need to drive servos in real time, which means we don't need stand-alone servo driver chips (thus a simpler board)
2) We also don't need “mirroring” subroutines to pass through servo commands in RC mode (simpler code)
3) Don’t need power regulator, since we’re using regulated output from the RC receiver (simpler board)
4) The built-in MUX failsafe is cheaper and simpler than using a stand-alone one.
I've taken a quick pass at the schematic and PCB (Eagle 5.0 format) for ArduPilot, although this will evolve as we go through the hardware testing cycle: Schematic, PCB board. You can buy the board here. Arduino code coming soon in alpha now.
All together, this can be the basis of a sub-$500 UAV:
Autopilot:
--ArduPilot PCB: $10
--Boarduino kit + FTDI cable: $35 (subtract $17.50 if you already have a FTDI cable)
--PicoSwitch: $20 (we'll probably build this in the board in the next rev)[UPDATE: Jordi's now incorporated that into the board above. It's a TinyAVR chip ("IC3", $2.75) and its associated programming interface jumpers ("ISP")]
--EM-406 GPS module: $60
--Multiplexer chip : $1
--8 Samtec TSW-108-25-G-T-RA right angle servo connectors (available as a free sample): $0
(That's a $110 autopilot, thanks to the open source hardware. By comparison, the Basic Stamp version of this, with processor, development board and failsafe board, would run you $300, and it's not as powerful)
Stabilization:
--FMA Co-Pilot: $70
Plane and RC equipment:
--Hobbico SuperStar (includes motor, battery and ESC): $109
--6-Channel radio system (with proportional control for channel 6, to calibrate FMA system): $109
--Three servos: $45
TOTAL: $440
Comments
I ordered this board just before you announced these latest updates. I've been tdy for my job anyway so it doesn't matter. Anyway, even though July is just around the corner as is the "new board" I'm still planning on building one (the version picture on this post is the one I ordered), is the program code available for this version?
I'll have two unmade older boards for the record books then.
Anyone want them ?
I'll order a new one when you let us know they are ready.
Thanks again for the pdf file.
This will probably be the final through-hole board, and is best for those doing their own soldering. The board will be working on after that will be surface mount, so it can be produced in an automated way and sold as a pre-made autopilot. Functionally, the two should be identical, with the exception that the SMD one may have a built in barometer, while that's something you add on a daughterboard in the through-hole version.
PDF of new board follows:
ardupilotBETA.pdf
I have not built the unit yet ?
Sould we transfer to these boards then ?
Any more updates on the way in hte near future ?
Could you also publish PDFs of the files. I have not yet got eagle installed.
(my bad)
ardupilotBETA.brd
ardupilotBETA.sch
Many thanks for that, which looks really helpful.
BTW, we have a new version of the board coming later today. If you haven't ordered the board, please wait for the new one.
It requires with two other files in the same folder (#DEFINES.h, and eeprom_float.h). If anyone wants to use it, just let me know. I'd be happy to help integrate it, or help with other coding if needed. This is a sweet project. email is tim at growdown dot com.
-Tim