Multivariable control of VTOL aircraft for shipboard landing

Abstract

The problem of the automatic landing of VTOL aircraft on small ships is considered. Linear quadratic optimal control theory is used to design a VTOL ship motion tracking controller. Optimal root-loci and step responses are obtained to study the dynamics of the closed-loop system. Standard deviations of the ship motion tracking errors, and of the VTOL control amplitudes are computed, illustrating the tradeoff between accurate tracking, and limited control authority. Multivariable robustness margins are also obtained. The tracking of the vertical motion presents the difficulty of requiring large variations of the VTOL total thrust, a control which is limited both in amplitude and in bandwidth. Lateral controls are less restricted, but the motions are strongly coupled, with some adverse couplings in the ship motions, and in the aircraft dynamics. The advantage of the LQ control theory is demonstrated however, by its ability to account for these couplings in a robust manner, and, when possible, to use them to limit the control amplitudes.

Nonlinear and Adaptive Control

“…These numerical feasibility studies help to point out the strengths and weaknesses of different design methodologies. References [6], [9], [ll], [12], [13], [MI, [30], [33] and [41 J summarize our research on designing controls for different aerospace systems. We discuss a subset of these in more detail below.…”

Saturated adaptive sliding mode control for autonomous vessel landing of a quadrotor

“…The relative modelling method can convert the vessel landing problem from general trajectory tracking problem of a quadrotor to a stabilisation problem of relative motion, which is enlightened by the application of the relative model in spacecraft rendezvous system [14, 15]. As for the vessel model, it is feasible to establish vessel model by using sinusoidal functions in [16] or physical model in [17]. To take the ship physical model into account and aviod complexity, we use a simple physical model that consists of sinusoidal functions [18] and 3‐DOF physical model [19] in this paper.…”