Design of Gain Scheduled Stability and Control Augmentation System for Quad-Tilt-Wing UAV

Abstract

This paper describes design of a stability and control augmentation system (SAS and CAS) for a small prototype quad-tilt-wing (QTW) unmanned aerial vehicle (UAV) developed by Japan Aerospace Exploration Agency (JAXA). Since the dynamics of QTW is originally unstable at most of the tilt angles in the both longitudinal and lateral-directional motions, stabilizing control is necessary for the practical operations. In this paper, a gain scheduled PD-SAS is designed by solving linear matrix inequalities (LMIs) formulated for a static output feedback problem. In addition to SAS, CAS is designed to improve the pilot handling. The CAS is derived based on an integral-type optimal servomechanism and controller order reduction technique. Both the controller gains are scheduled with the tilt angles, since the dynamic characteristics of QTW change widely according to the tilt angles. Nonlinear human-in-the-loop simulation results have shown that the obtained gain scheduled controllers stabilize the QTW in almost all the tilt angles and provide good tracking performance for the attitude commands. NomenclatureA p_i = system matrix of QTW model A c_i = system matrix of linearized PFCS model B p_i = input matrix of QTW model B c_i = input matrix of linearized PFCS model C p_i = measurement matrix of QTW model C c_i = measurement matrix of linearized PFCS model u,v,w = velocity of QTW along body axis p,q,r = angular velocity T d = time constant of PD controller τ w = tilt angle, deg stick θ δ = pitch stick input from remote ground pilot, % clc δ = collective stick input from remote ground pilot, % stick Φ δ = roll stick input from remote ground pilot, % stick Ψ δ = yaw stick input from remote ground pilot, % θ = pitch angle φ = bank angle Q y , Q u = weighting matrix 0 Γ = optimal value of a performance index

Design, Flight Mechanics and Flight Demonstration of a Tiltable Propeller VTOL UAV

“…Suzuki et al, studied the attitude control of quad tilt-wing UAV 20 . The design of gain scheduled stability and control augmentation system for quad-tilt-wing UAV study has been performed by Tokoti et al 21 .…”