Abstract

This article proposes a novel hybrid two-layer control architecture for 3‑D spatial trajectory (x, y, z) tracking of a F/A-18 aircraft model under parametric uncertainties. First, an outer loop control subsystem is designed based on sliding mode control (SMC) theory. This SMC subsystem accomplishes spatial trajectory (x, y, z) and sideslip angle β control using angular velocity vector—comprising roll rate p, pitch rate q, and yaw rate r - as virtual control input, in conjunction with the derivative of the thrust Tx . Second, a composite inner loop control subsystem, including (i) a geometric homogeneity-based finite-time control law and (ii) a super-twisting (STW) control law, is developed. The inner loop control subsystem is designed to control aircraft roll, pitch, and yaw angular velocities (p, q, r) using aileron, elevator, and rudder control surfaces. The inner loop control subsystem achieves finite-time convergence of the actual (p, q, r) to the computed virtual angular rates derived for the outer loop control. Lyapunov analysis establishes the closed-loop system’s stability. Simulation results for a 1800 climbing turn and helical path-following exhibit precise trajectory tracking performance against large parametric uncertainties.

Keywords

hybrid two-layer flight control, F/A-18 aircraft, super-twisting (STW) control, robust finite-time control, 3-D spatial trajectory control, uncertain nonlinear systems