Ahh!! CRASH and BURN!!
I had planned to use the Pico-Pilot and Pico-GPS for the autopilot in my UAV, but I have now discovered that since Jan 2007, they have been classed as MILITARY technology and are controlled by US Export License regulations. Specifically the regulations cover,
a. “UAVs” having any of the following:
a.1. An autonomous flight control and navigation capability (e.g., an autopilot with an Inertial
Navigation System); or
a.2. Capability of controlled flight out of the direct visual range involving a human operator
(e.g., televisual remote control).
b. Associated systems, equipment and components as follows:
b.1. Equipment specially designed for remotely controlling the “UAVs” controlled by 9A012.a.;
b.2. Guidance or control systems, other than those controlled in Category 7, specially designed for
integration into “UAVs” controlled by 9A012.a.;
b.3. Equipment and components specially designed to convert a manned “aircraft” to a “UAV”
controlled by 9A012.a.
Note: 9A012 does not control model aircraft.
Despite the last sentence, UNAV, who make the Pico Pilot have now told me that none of the applications for export licenses they have made this year have yet been granted. Back to the drawing board.
The other common low cost option for an autopilot seems to be based on the FMA Co-Pilot for flight stability with an additional board such as the RCAP2 plus a GPS receiver for navigation. While a cheaper alternative, I had already discounted this approach because it is based on thermopile sensors. For my terrain, I cannot get a clear 360degree view of the horizon to calibrate the system before launch. In addition, the various different terrain types , forest, grassland, lakes etc. could give problems in flight, irrespective of the temperature differences that can occur if different parts of a valley are in sunlight or shade.
During my initial research into autopilots, I also looked at the Paparazzi project. While there is a wealth of open source stuff there, the current Tiny autopilot still uses thermopile sensors for stability, although it does have an on board GPS unit for navigation. An all singing, dancing IMU with gyro's , mangetometers etc. is under development. Although all the designs are published, there is still no commercial source of assembled units or PCB's.
A recent post on this forum (can't find it now), talked about the the UAV development board from Sparkfun. I had a brief look at this, but initially discounted as they claim that the firmware is a guideline only. It is also written in assembly code and I am far to old to start writing in assembler again. Still I shall have another look at this over Christmas, as the board does have a proper IMU with 2 gyros and a 3 axis accelerometer.
Conclusions and Questions