Robust Adaptive Output Feedback Control for a Class of Underactuated Aerial Vehicles with Input and Output Constraints

Trong-Toan Tran,Duc-Duy Nguyen,Viet-Long Nguyen,Nguyen-Vu Truong,Tan-No Nguyen

doi:10.1155/2020/7193136

Abstract

This paper addresses the problem of nonlinear robust adaptive output feedback controller for a class of underactuated aerial vehicles with input and output constraints. To solve the problem, the modular design strategy is proposed for the control design. By using the neural networks (NNs) to approximate system uncertainties and observers to reconstruct system states, robust adaptive output feedback controllers are developed. By using a combination of saturation functions and barrier functions, input and output constraints are simultaneously dealt with. The design methodology shows that a cascaded system of an input-to-state stable (ISS) subsystem driven by an ultimate bounded (UB) subsystem enjoys ultimate boundedness property. In addition, the tracking error converges to adjustable neighbourhoods of the origin.

Highlights

In recent years, control of underactuated systems has attracted much attention
Unlike the fully actuated system in which the number of independent control inputs is equal to degrees of freedom (DOFs), the underactuated system has fewer independent control inputs than DOFs [1, 2]
In the control design for underactuated systems, all DOFs cannot be controlled; instead, a portion of DOFs is controlled to have desired behaviours while remainders are required to be bounded. is requirement leads the system in the question to a non-minimum phase system [8]

Summary

Introduction

Control of underactuated systems has attracted much attention. Unlike the fully actuated system in which the number of independent control inputs is equal to degrees of freedom (DOFs), the underactuated system has fewer independent control inputs than DOFs [1, 2]. By constructing the underactuated aerial vehicle as a cascaded structure consisting of fully actuated subsystems, the robust adaptive output feedback control can be separately designed for each subsystem. In this setting, the observers are employed to reconstruct system states for the feedback and the radial basis function NNs (RBF NNs) are used to approximate the system uncertainties. E main contributions in this paper include the following aspects: (i) e modular design strategy is proposed to design the robust adaptive output feedback control for the class of underactuated aerial vehicles with taking into account multiple constraints. Given two vector a􏽥, 􏽥b ∈ Rn, a􏽥 ≤ 􏽥b denotes a􏽥i ≤ 􏽥bi, i 1, · · · , n

Problem Formulation and Preliminaries

Proof of Lemma 3

Proof of Theorem 2