Generalized predictive control of the aircraft system with actuator saturation to prevent Pilot-induced Oscillations
Amplitude and rate saturations are one of the problems of flight control systems which puts the closed-loop system stability at risk. These nonlinear elements are mainly responsible for the type II pilot induces oscillations (PIOs). In this paper, a robust unconstrained generalized predictive controller (GPC) with a self-tuning regulator (STR) structure is designed in the frequency domain to prevent the type II PIOs. Furthermore, the sensitivity function is used for tuning the GPC parameters and investigating the stability and robustness of the system against the uncertainties of the controller parameters. To get better results, a constrained GPC is further designed considering the rate, amplitude, and both saturations. Rate and amplitude saturations are considered as input constraints in the design stage. Finally, the performances of the proposed controllers are compared to that of a PID controller.