AUTO-PILOT

Thank you so much .This gave me a brief idea on how to use the auto pilot which was very helpful.

There's lots of good resources on the internet as well as at any decent public library(any books on "control systems/theory" will have an explanation of PID), that can explain it better than me, but I'll still try.

1.) Proportional control is exactly what the name says. The output is always proportional to the input, so the further your desired heading/pitch from your actual heading/pitch("error rate"), the larger reaction your craft will have at a given "P value".

2.) The integral is a measure of the "error" over time, basically meant to recalibrate the proportional over time as it loses accuracy. Unfortunately, that function is more suited to a repetitive manufacturing process than an auto-pilot(in an aircraft, the actual direction of travel isn't necessarily the intended direction of travel, so a PID with >0 integral will try to fix that by increasing/decreasing P in a somewhat random way which causes wobble and loss of control)

3.) Derivative "slows" the proportional as it nears it's target in order to reduce "overshoot". An auto-pilot using proportional only("P control") wouldn't work very well since it would wobble back and forth between two extremes with the desired heading somewhere in the middle. Every time the autopilot corrects the heading, the proportional control pushes it just enough to miss the target and have to start all over again. This is where the derivative comes in: as the "error" goes down, the proportional is also decreased proportionally until the error is either minimum or 0, and vice versa (if error goes up, proportional increases)

All of these have their names rooted in the type of math performed. Proportional is just a proportion, integral is an integral, and derivative is a derivative, so if you understand upper level math(high school/early college) then it should be easy to figure out.

i'm no expert but here's what i've experienced so far:
(you can also read the tooltips if you hover over the sliders)

Proportional: the "main part" of the autopilot, it dictates how much correction power is used to turn the craft to the set orientation
Integral: basically a "boost" to proportional, it may sometimes add more or less turning power, it's sort of unpredictable, but i recommend keeping it at a low level (usually just zero)
Derivative: the "counter-force" to the other two, it dictates how much correction power is used to correct the craft to the set orientation if it goes beyond said point