Well it has taken me about a month but I think I finally have a plan for a UAV.
Please excuse my childlike MS Paint style diagrams! This is what I would like it to be able to do. It is using in the BASIC Stamp
1. Have waypoints that include altitude.
2. Be able to take Digital Photos
3. Have a lost plane alarm after landing (or crashing!) in long grass etc… This could be turned on via Aux channel on the receiver. Alternatively this could turn on landing lights for night or dusk landings.
4. Control of the autopilot from the Gear channel that totally bypasses the Basic stamp in manual control mode in case of Basic Stamp Problems.
5. 2X16 LCD (optional) to display maximum altitude reached or maximum speed reached, waypoint info etc.. (I haven’t really thought about this bit yet).
6. After all that was working…. (and if the thing can still get off the ground from all the extra weight!!) another thing that I was thinking about was having a voltage sensor (Lipo alarm) on the main battery. (I have one of these on my Trex 450 SE V2 Helicopter) It would monitor the main battery voltage, when the voltage dropped (if it was a 11.1 V Lipo) to say 10.5V the battery would be almost 80% depleted. (after 80% the battery will be damaged)
The voltage sensor would then trigger a relay that would switch to a smaller backup battery and also trigger the BASIC Stamp to return to home. The home co-ordinates would be obtained when the autopilot was engaged.
is a circuit I found for a RC Switch, I have not tried this yet. This
is the relay I think I will use. (I had to because of the name!) [UPDATE 2/3/8] I am going to use this
instead to save space and weight.
The other idea I had was for altitude control. If the Basic Stamp is controlling the elevator for altitude I can see that it might be easy for the UAV to get into trouble as it does not know the angle it is climbing or descending. It could be resolved by adding more sensors but I thought this might be easier and less programming.
I am going to mount the FMA Co-pilot onto a see saw mount that is controlled by a servo. The Basic Stamp would then just control that servo. If you wanted the UAV to climb at an angle of 10 degrees, just move the FMA servo by 10 degrees.
The FMA Co pilot would then control the elevator to keep the FMA co pilot level, which means the UAV would be climbing by 10 degrees. (I think)
Also in the altitude subroutines I was planning to turn off or turn down the throttle channel when the UAV is descending to save power. And then switch it back to where it was when it reached the desired altitude. Maybe even add a bit more power for climbing. After a few tests I should be able to work out what percentage the throttle channel would need to be at to hold altitude.
is the Plane I am planning to use for this project, There seems to be more room inside for electronics that a foamy.
If anyone has any better ideas or reason why they think this wont work too well please let me know. As I start building I will post some pictures.