After a long period of bad, rainy & windy weather, we finally had a perfect weekend. Sunny and only 1-2 BF wind. Perfect for testing my autopilot.
After some first tests on Saturday, I discovered my EB-85 GPS was also suffering from a known firmware problem. After a minute of flight, the data coming from my GPS module was useless, and my plane kept flying North instead of circling around the home waypoint. Damn you, E-Tek!
Anyhow, as a quick hack to make things work a bit more reliably, I hot-restart the GPS unit every 50 seconds. Also, I set the maximum roll angle the autopilot will use to 17 degrees. These gentle movements will less likely confuse the GPS unit.
And it worked! The easystar circled nicely around it’s one waypoint (being the take-off position). For 25 minutes, my transmitter was laying on the ground while I was just watching the plane. Must have been a weird sight for the people passing by for a walk on this beautiful day :-)
These are some other things I’m having in mind for my autopilot:
- Programmable waypoints
- Improve attitude stabilization on fast unstable planes
- A downlink with some kind of groundstation software
- Document the code better
- Create a new PCB with static and maybe a dynamic pressure sensor… + using a dsPIC with more flash ram.
I only I had more time :-)