Command filtered model-free robust control for aircrafts with actuator dynamics

Abstract

In this paper, a command filtered model-free robust (CFMFR) controller is proposed to regulate attitude angles of an aircraft with parameter uncertainties and disturbances to track the given reference signals. For the first subsystem of the controlled plant, the incremental nonlinear dynamic inversion (INDI) is applied to design incremental virtual control law. While the time-delayed control (TDC) method is used to design the control law by integrating sliding-mode technique considering the nominal value of the control effectiveness matrix is unknown. The adaption laws of the control gain are constructed by Lyapunov control theorem. Not only the actuator dynamics of the control surfaces are considered, but also the noises, biases, and time delays of the measurements of the control surface deflection angles are taken into account. Therefore, the command-filtered backstepping is utilized to compensate for the actuator dynamics and filtered errors, and the modified stable linear filter is developed to handle the measurement errors. The stability of the whole closed-loop system, including the compensated signals which are the outputs of the stable linear filters, is analyzed by using Lyapunov theory. The numerical simulation results demonstrate effectiveness of the proposed CFMFR control approach with updating matrix.