Quaternion-based Adaptive Backstepping Fast Terminal Sliding Mode Control for Quadrotor UAVs with Finite Time Convergence

TL;DR

This paper introduces a quaternion-based control framework for quadrotor UAVs that ensures finite-time convergence, robustness against uncertainties, and avoids singularities, improving accuracy and actuator safety.

Contribution

It develops novel quaternion-based adaptive backstepping and fast terminal sliding mode controllers that handle uncertainties and singularities, with enhanced convergence and reduced control chattering.

Findings

Controllers achieve finite-time convergence.

Significant reduction in control signal chattering.

Validated robustness against uncertainties and initialization errors.

Abstract

This paper proposes a novel quaternion-based approach for tracking the translation (position and linear velocity) and rotation (attitude and angular velocity) trajectories of underactuated Unmanned Aerial Vehicles (UAVs). Quadrotor UAVs are challenging regarding accuracy, singularity, and uncertainties issues. Controllers designed based on unit-quaternion are singularity-free for attitude representation compared to other methods (e.g., Euler angles), which fail to represent the vehicle's attitude at multiple orientations. Quaternion-based Adaptive Backstepping Control (ABC) and Adaptive Fast Terminal Sliding Mode Control (AFTSMC) are proposed to address a set of challenging problems. A quaternion-based ABC, a superior recursive approach, is proposed to generate the necessary thrust handling unknown uncertainties and UAV translation trajectory tracking. Next, a quaternion-based AFTSMC is developed to overcome parametric uncertainties, avoid singularity, and ensure fast convergence in a finite time. Moreover, the proposed AFTSMC is able to significantly minimize control signal chattering, which is the main reason for actuator failure and provide smooth and accurate rotational control input. To ensure the robustness of the proposed approach, the designed control algorithms have been validated considering unknown time-variant parametric uncertainties and significant initialization errors. The proposed techniques has been compared to state-of-the-art control technique. Keywords: Adaptive Backstepping Control (ABC), Adaptive Fast Terminal Sliding Mode Control (AFTSMC), Unit-quaternion, Unmanned Aerial Vehicles, Singularity Free, Pose Control