Re: Re: [Paparazzi-devel] custom autopilots

[Martin Mueller]

Hi Maikel,

some general thoughts on where to run the Paparazzi software. There should be 
no problem to compile and run the software on a Linux platform. That is where 
the (x86) simulation runs naturally. Some people have done that before although 
I am not sure if they actually flew with it.

The current philosophy for Paparazzi is that there is a custom board for 
interfacing to specific hardware like sensors/servos and running the low level 
control loops. We have the need for some adapter to the hardware anyway (what 
you use Pololu for) and by that we have a safe and well tested platform for the 
critical software part. The higher level stuff like following a flight plan can 
then also be done on that board or an attached Linux board, e.g. the Gumstix 
Overo.

Using Linux for the low level control loops means more than just running the 
software. You have to make sure that the realtime constraints are met and this 
means e.g. that under all conditions the attitude control loop is called 
precisely with (at least) 60Hz for the fixed wing, some 100Hz for a rotorcraft. 
That might simply work by itself with a fast hardware and no other application 
running. It will get rougher the more software you want to run on that board.

It would be interesting to see what results you get from running Paparazzi on 
your Linux hardware but there will be more to do than just a few Makefile 
changes.

The reliable, most used Paparazzi platform is the ARM7 based one. That is the 
Tiny, TWOG and derivates. Most people fly them with thermopiles and find a fast 
way to a working UAV by that. The new ARM Cortex-M3 based Lisa platform is 
flown by some people but has not reached the "mass market" yet (sure it will). 
Rotorcrafts are flown with IMUs on both platforms and there are more and more 
people doing that with fixed wings also.

For a hassle-free start a TWOG with an ublox GPS or a Tiny might be a good 
hardware. Go through the wiki pages and read as much as possible.

Martin