Thanks CodingBadly,
You are welcome! And a BIG thank you to br3ttb!
- For normal operation, use the standard PID controller to control my direction of aim and just adjust the parameters based on elevation (every 10K ft or so)
That certainly seems reasonable.
By modeling the behaviour at different elevations (air at different pressures flowing over a fin is a fairly well researched subject) you may be able to develop something more accurate. For example: with the lower pressure at higher altitudes it seems reasonable that the fins will have to be at steeper angles to get the same effect. You may be able to simply multiple the PID output by an amount based on elevation.
- As i monitor my spin rate, if I ever detect that my spin rate is greater than "X", then put controller in manual mode, take over control of the fins and brake the spin until its less than X. Then re-enable the PID controller.
You will very likely want to ensure the transition from manual to auto is "bumpless". br3ttb will have to advise you on how to do that.
I was hoping to "mix" the speed and direction into a single equation to give a magical answer, but as was pointed out, a PID controller of this type is first order control only.
How quickly can the fins respond to a command?
Can the fins be individually controlled?
How accurate is "am I spinning" system?
Do you mind providing pictures of the system?
my differential equations classes are a distant memory
Dittio.
My controls theory classes were long ago
If I had known my career path I would have added two classes to my curriculum: Controls Theory and Mind Reading. ;D
Plus the 80 hour debug weeks
Yikes!