Robust Super-Twisting Sliding Mode Backstepping Control Blended with Tracking Differentiator and Nonlinear Disturbance Observer for an Unknown UAV System

Sungbum Park,Seongik Han

doi:10.3390/app12052490

Abstract

In this study, we examined the robust super-twisting sliding mode backstepping control (SBSC) method, which employed a tracking differentiator and nonlinear disturbance observer for a hexacopter unmanned aerial vehicle (UAV) system. To realize robust tracking control performance for a highly coupled nonlinear hexacopter UAV system, a super-twisting sliding mode control method was combined with designing stabilizing controls of backstepping control (BSC) applied to the UAV system. Furthermore, the differentiation issue of the virtual control and compensation of transformation error in the conventional BSC design were bypassed via a new continuous tracking differentiator structure. Additionally, a new disturbance observer based on the proposed tracking differentiator was considered to estimate uncertainties of the hexacopter UAV. Comparative simulation results demonstrated that the proposed tracking-differentiator-based SBSC scheme (PTSBSC) blended with the tracking differentiator and nonlinear disturbance observer exhibits improved performance when compared to that of conventional BSC and disturbance observer systems.

Highlights

Developments of the rechargeable battery source, brushless DC motor, and various related techniques lead to increased research unmanned aerial vehicles (UAVs)
Simulations for three cases, including the nominal system, perturbed system without the observer, and perturbed system with the observer are conducted to evaluate the performance of the proposed controller and disturbance observer for the hexacopter UAV system
A super-twisting sliding mode backstepping control blended with a new tracking differentiator and disturbance observer based on the concept of the proposed tracking differentiator was examined to realize robust tracking control performance of a hexacopter UAV system

Summary

Introduction

Developments of the rechargeable battery source, brushless DC motor, and various related techniques lead to increased research unmanned aerial vehicles (UAVs). The multi-rotor UAVs exhibit significant advantages in terms of hovering capability and maneuverability involving side and backward movement, vertical take-off and landing in 3D space, and lower maintenance cost than other small aerial vehicles [1–4]. Most multi-rotor UAVs adopted a four-rotor mounted quadrotor structure, and they exhibit limited power for heavy cargo delivery. UAVs mounted with more rotors, such as hexacopter and octocopter UAVs, when compared to four rotors, were developed to enforce lifting and higher capabilities in terms of flying time [5–10]. When considering the efficiency of UAVs, the hexacopter is more feasible than the octocopter because an increase in the number of rotors leads to an increase in size and cost

Methods

Results

Conclusion