litinoveweedle
3rd Jun 2014, 16:41
Hello,
first I am not a pilot, more aviation enthusiast, with avionics programming for simulators as a hobby. I would like to ask here for help of professional pilots community. I currently try to simulate Honeywell GP-300 / IC-800 AFCS components, as used in Do-328 and probably ATR planes as well. But IMHO same principles, I am searching for, applies to other autopilots / AFCS as well.
For some lateral (VOR, LOC, BC..) and vertical (ALT SEL, GS..) modes AFCS has two phases, the capture and tracking. The capture mode is normally identified by star i.e. VOR*, ALT* The conditions when AFCS will switch from capture into tracking phase differs for each mode, but mostly are based on current error and error rate (for example for ALT SEL could be altitude error and vertical speed).
Once mode is in tracking phase, AFCS will optimize its guidance to keep error on minimum level, together with lowering controllers gains and setting lower pitch and rolls limits.
Now here is my question: Lets assume, that you are in track mode, flying manually following FD. What will happened, if you intentionally stops to follow FD guidance and fly away from the target? Will increase of the error and/or error rate (when reaching some threshold) switch AFCS back from tracking to capture phase? Or once given mode is in tracking phase, it will never switch back to capture, even if capture phase could be faster to return on target? (as capture phase is typically more aggressive - higher gains and roll/pitch limits and rates).
Hopefully I described my theoretical problem well enough. :} I would welcome any help or hint, thank you.
first I am not a pilot, more aviation enthusiast, with avionics programming for simulators as a hobby. I would like to ask here for help of professional pilots community. I currently try to simulate Honeywell GP-300 / IC-800 AFCS components, as used in Do-328 and probably ATR planes as well. But IMHO same principles, I am searching for, applies to other autopilots / AFCS as well.
For some lateral (VOR, LOC, BC..) and vertical (ALT SEL, GS..) modes AFCS has two phases, the capture and tracking. The capture mode is normally identified by star i.e. VOR*, ALT* The conditions when AFCS will switch from capture into tracking phase differs for each mode, but mostly are based on current error and error rate (for example for ALT SEL could be altitude error and vertical speed).
Once mode is in tracking phase, AFCS will optimize its guidance to keep error on minimum level, together with lowering controllers gains and setting lower pitch and rolls limits.
Now here is my question: Lets assume, that you are in track mode, flying manually following FD. What will happened, if you intentionally stops to follow FD guidance and fly away from the target? Will increase of the error and/or error rate (when reaching some threshold) switch AFCS back from tracking to capture phase? Or once given mode is in tracking phase, it will never switch back to capture, even if capture phase could be faster to return on target? (as capture phase is typically more aggressive - higher gains and roll/pitch limits and rates).
Hopefully I described my theoretical problem well enough. :} I would welcome any help or hint, thank you.