DEMENTOR - Building a home solar powered UAV Unmanned Aerial Vehicle
This project it not done, I just wanted to share what I have done so far on it. I have all my life been fascinated of helicopters and aircrafts. I got this idea in my head for some time now, and I can't get rid of it. Think of building a craft capable of flying indefinitely, and maybe around the world on just the power of the sun. This it not a new idea, there are many projects like the NASA Helios, and the SOLONG project. But this are high cost project, and hardly done at home with a shoestring budget .. yet :)
I'm just a 3D guy so I know NOTHING of aerodynamic, lift drag etc.. so I asked one who know it all and where eager to share this information Mr Google (or Ms ;)
After some surfing i got the general ides and did a quick design in 3D of the airframe.
After that a started looking at what fun electronics to put in the plane .. or avionics when they are in a plane ;)
I really liked to have some sort of standard linux dist running the system, because then you can plug in any fun things you may find without doing some very complicated programming.
My brother sent me this very good UAV control board from spark fun electronics (another SFE he :) It have build in gyros and a very capable PIC 18 processor.
The idea was to have this board run the "balans" part of the system, and have another computer doing the actual plotting and controlling, But if that computer crashed or got messed up, the plane would still fly and get to the next ordered gps-point, and eventually a timer would reboot the big computer and normal control would come back online, without crashing the plane.
A Linksys WRT-54L strip down for the scale. Just weigh 150 grams. Another idea is to run the control system inside the WRT-54, with an alternate firmware and not to have another computer at all, but we'll see. The 2.4GHz would be good for short rage, high speed communication for up to 1km.
Long range communication up to 50 km would be accomplices by using X25 over VHF radio. This are some PMR 0.5 W license free radios that run on 446 Mhz band. But only at the limited speed of 9600 bps. I'll rebuild one of these for the plane and the other for connection to my laptop.
I searched the web trying to find some good cheep altitude sensor, but anything remotely close to real avionics cost MUUUUUUUCH money. So here is an alternative. This is a small LIDAR (Light Direction And Ranging) device and just cost as a pack of ice cream. It uses an scrambled infrared beam, and can detect accurate distance up to 800 meters, and just weigh 170 grams. The interface of it is standard serial 232.
For altitude under 800 meter I use the LIDAR, and above that I'll use the GPS (In theory). According to swedish law, I must stay under 300 meters and away from populated areas and controlled airspace. But I live in the forest so that is easy :)
Or low budget home built sensor:
It would be cool to set up an priority and messaging environment in the plane, so sensors just post there findings, and a "logic engine" interpret them, and issue command to servos and motors. So the plane would have a simple AI (artificial intelligence)
For me to be able to control the plane, I was thinking of modifying an 3D environment running on my renderfram (Helmer). It can easily be modified to receive telemetry from the plane over SSH (secure shell) and displaying a real time model. So when the plane is out of rage for high speed communication (camera/video feed) I just use the slow X25 over VHF to feed med attitude info from the plane and move the 3D model accordingly.
But... So far this is the plane. Just some pieces in a box and the idea in my head. :)
More to come: