A modified method for satellite attitude control system in presence of novel actuators is proposed in this paper. The attitude control system is composed of three fluidic momentum controller (FMC) actuators that are used to control Euler angles and their dynamics is considered in satellite attitude equations as well. L1 adaptive control is utilized for satellite three-axial ...

The paper presents new results on the verification and in–flight validation of an L1 adaptive flight control system, and proposes a general methodology for verification and validation of adaptive flight control algorithms. The proposed framework is based on Rohrs’ counterexample, a benchmark problem presented in the early 80s to show the limitations of adaptive controllers developed at that tim...

This paper presents a modified nonlinear longitudinal model for an air-breathing hypersonic vehicle and the design of an L1 adaptive controller for it. It is assumed that the mid-fuselage is a rigid-body, while the aft-fuselage is linearly elastic, and a rigid all-movable elevator is fixed at the end of the aft-fuselage. In the resulting mathematical model, the pitching moment depends not only ...

In this paper we exploit the connection between disturbance observer and L1 adaptive control theories. We consider L1 adaptive output–feedback control framework, for which the L1 reference controller is equivalent to the disturbance observer. Using this fact, we investigate several properties of the disturbance observer architecture, leading to various filter design methods towards verification...

A modified parabolic equation for adaptive monotone difference schemes based on equal-arclength mesh, applied to the linear convection equation, is derived and its convergence analysis shows that solutions of the modified equation approach a discontinuous (piecewise smooth) solution of the linear convection equation at order one rate in the L1-norm. It is well known that solutions of the monoto...

Adaptive control techniques have the potential to address many of the special performance and robustness requirements of flight control for unmanned aerial vehicles. L1 adaptive control offers potential benefits in terms of performance and robustness. An L1 adaptive output feedback control design process is presented here in which control parameters are systematically determined based on intuit...

This research focuses on development of L1 adaptive output-feedback control. The objective is to extend the L1 adaptive control framework to a wider class of systems, as well as obtain architectures that afford more straightforward tuning. We start by considering an existing L1 adaptive output-feedback controller for nonstrictly positive real systems based on piecewise constant adaptation law. ...

The objective of this document is to provide a technical response to a widely circulated article [1], co-authored by P. Ioannou, K. Narendra, A. Annaswamy, S. Jafari, L. Rudd, R. Ortega, and J. Boskovic, in which the authors “have come together” to express “with one voice” their “growing concern” about the claims on performance and robustness guarantees of L1 adaptive control. The article has b...

This paper presents the design and experimental implementation of an L1 adaptive control on a tethered underwater vehicle. This controller, well known for its fast adaptation and its robusntess, is proposed to be applied for the first time in the field of underwater vehicles control. This paper summarizes the implementation and experimental results obtained on a modified version of the AC-ROV u...