[Paparazzi-devel] Paparazzi Autopilot for Linux

[Pat Hickey]

Hi all,

As part of the Rutgers University team entering the AUVSI UAS
competition, Bradley Lord and I ported the Paparazzi airborne code to
run on a Linux-based single board computer. We needed a powerful
onboard computer to develop our imaging system, and in order to
consolidate hardware and make the software more extensible, we decided
to run the autopilot on that computer as well.

To replace a Tiny v2, we used a Beagleboard and many devices which are
very similar to those found in a traditional Paparazzi setup. The few
major changes had to do with PPM input and PWM output: instead of
processing any signals from the safety R/C radio, we leave the input
selection up to a Pololu 4-channel servo multiplexer. We used a Pololu
Micro Maestro device for servo output from a USB device. The  Micro
Maestro has a programmable failsafe mode if servo updates from the
flight computer have timed out.

We haven't had to worry about real-time performance- Paparazzi is very
reliable on the 500MHz processor, and took up only 5% of the available
power. We trimmed out much of the code that was specific to the arm7
and real-time responsibilities. We're also working on two extensions
(an IMU, and integration with gpsd) that will extend Paparazzi using
higher level languages (like C++, Python) using sockets and message
queues. All of these changes make our platform a bit more flexible,
and it might be a good option for a research, sensing, or imaging
platform.

We currently use a thermopile based attitude tracking system just like
the Tiny uses, but we're moving to an IMU soon.

I've posted our code on Github
(http://github.com/pchickey/paparazzi-linux-release/), and I prepared
a website describing our project that has more details about our work:
http://moreproductive.org/autopilot/.

We owe a great deal of thanks to the Paparazzi developers and
community for providing the excellent software we built on. We look
forward to continuing work on this project. I'm happy to correspond
with anyone who needs help using our code.

Pat Hickey