Best altitude hold ever

Today we lit up the derivative term of the PID loop and Vicacopter had the best altitude hold ever. This time, there was no ground effect to save her. It was in dead calm winds, but still better than anything achieved in dead calm winds before. Even the mighty Jack Crossfire could never dream of holding such a stable altitude, as seen in the many overhead lighting shots.

Clearly, full PID loops with hand picked constants are the way we're going to do all positioning. The big question is does cyclic require

horizontal position -> target velocity
velocity error -> cyclic deflection

or

horizontal position -> target velocity
velocity error -> target tilt
tilt error -> cyclic deflection

or

horizontal position -> target tilt
tilt error -> cyclic deflection

The hand picked constants follow general rules:

P and D factors are around 0.02 and equal.
I factor is around 0.0001.
The derivative is based on the current sample - the sample 1/2 a second ago.
Output limit is around 0.1
Other limits aren't necessary, but we limit the integral to 0.1 just in case.

This all depends on the sample rate being 35Hz. The derivative is really the rate of change of the Kalman filter climb rate, a very noisy value but effective.

Sonar altimeter may be used as a boundary sensor in case GPS drifts high and Vicacopter comes down to head level. The trick with any sonar altimeter is switching it on only when Vicacopter is in the air. It needs ground clearance to calibrate itself.

Well the PIC stopped accepting any new programs at all. Maybe the code protect bits got flipped on by a static discharge. Maybe its in circuit serial programming BIOS got destroyed. Time to order another salvo of PIC replacements.