The inner loop, a feedback control loop, is designed as a proportional – integral – derivative (PID) controller in order to eliminate unknown parts of the plants such as input-nonlinear elements, or unknown system disturbances. The outer loop, a learning feed-forward control (LFFC) loop, is designed based on the Model Reference Adaptive System algorithms called MRAS-based LFFC for compensating the cross-couple and non-linear elements. | Design of Feed-back combining learning Feed- forward control system for quadcopter craft
