0018-9251 (c) 2018 IEEE. Personal use is permitted, but republication/redistribution requires IEEE permission. See http://www.ieee.org/publications_standards/publications/rights/index.html for more information. This article has been accepted for publication in a future issue of this journal, but has not been fully edited. Content may change prior to final publication. Citation information: DOI 10.1109/TAES.2018.2871435, IEEE Transactions on Aerospace and Electronic Systems 1 Effect of Asymmetric Control Constraints on Fixed-wing UAV Trajectories Sulakshan R. Arya, Sachit Rao, Member, IEEE, and B. Dattaguru Abstract Reference trajectories, for the longitudinal states of a fixed-wing UAV subjected to asymmetric con- trol constraints, are distinguished using the characteristics of Regions of Asymptotic Stability calculated as ellipsoidal domains by solving Linear Matrix Inequalities. These domains are used to determine the maximum allowable deviations from the reference, for which stable closed-loop tracking can be ensured. Constraints are imposed on a linear state feedback controller with the saturation modeled as a sector non-linearity. Index Terms Control Saturation, Ellipsoidal Domains, Fixed-wing UAVs, Flight Control, Linear Matrix Inequal- ities, Regions of Asymptotic Stability, Trajectory Selection I. I NTRODUCTION Reference trajectory selection forms an important design aspect for the operation of dynamic systems, such as fixed-wing Unmanned Aerial Vehicles (UAVs), which are subjected to actuator or control constraints. These constraints, as mentioned in [1], render linear systems to be non- linear, and more importantly, do not guarantee closed-loop stability for all initial deviations. Thus, in the case of UAVs, it becomes essential to consider these constraints, so that allowable deviations, from the reference, can be characterised for which stable behaviour can be assured. As there exist several types of UAVs, the characteristics of fixed-wing UAVs–which form the subject of this paper–are briefly described. S. R. Arya and B. Dattaguru are with the Department of Aerospace Engineering, Jain University, Jakkasandra Post, Kanakapura Taluk, Bangalore Rural District–562 112, India e-mail: sulakshan.r.arya,datgurb@gmail.com. Sachit Rao is with the International Institute of Information Technology, Bangalore, India, e-mail: sachit@iiitb.ac.in. Manuscript received May 08, 2017.