Adaptive Trajectory Tracking Control for Rotorcraft Using Incremental Backstepping Sliding Mode Control Strategy

Abstract

This paper investigates the adaptive incremental backstepping sliding mode control for the rotorcraft trajectory-tracking control problem to enhance the robustness to the matched uncertainty in the model. First, the incremental dynamics is used for the control design to exclude the adverse effect of the mismatched model uncertainties on the trajectory-tracking performance. Secondly, the sliding-mode control strategy is adopted in the second design stage of the backstepping controller, and the effect of switching gains on the controller robustness is thoroughly studied using the rotorcraft model with different levels of the matched uncertainties. To clarify the robustness enhancement using the adaptive selection of switching gains, this paper chooses three different control structures consisting of the traditional backstepping control and two backstepping sliding mode controls with the fixed or adaptively adjusted switching gains. These control designs are applied to the trajectory-tracking control for the helical-turn maneuver of the Bo-105 helicopter to compare their relative robustness to the matched uncertainties. The results prove that adaptive incremental backstepping sliding mode control shows much higher robustness than other two designs, and the controller even with the fixed switching gains can be used to improve the robustness of the pure backstepping control design. Therefore, the present adaptive incremental backstepping sliding mode control is effectively applicable with the rotorcraft model which typically contains many different sources of both matched and mismatched uncertainties.

An Approach to Air-to-Surface Mission Planner on 3D Environments for an Unmanned Combat Aerial Vehicle

“…Incremental Backstepping Control (IBSC) guarantees stability across all Operational Flight Envelopes (OFE) based on the Lyapunov stability theory and is not affected by mismatched uncertainty. For this reason, there have been many approaches to design a controller based on the IBSC concept [34][35][36][37][38][39][40], and this paper also uses an IBSC-based tracking controller [33]. The reference trajectory was directly used as a feedback signal to obtain excellent tracking performance.…”

Robust Trajectory-Tracking Control of a Rotorcraft Using Immersion-and-Invariance-Based Adaptive Backstepping Control

“…Equation (23) shows that the TF method adopts integral feedback of the trajectory-tracking error z 2 . From Equation (23), one can observe that two adaptive update laws are excited by the same input z 2 .…”

“…Previous studies have been conducted to effectively cope with the rotorcraft's underactuated system while extending controllers' robustness against existing uncertainties [22,23]. Both approaches are based on driving incremental dynamics out of the original dynamics, and the slack variable approach has been used to reduce design parameters and simplify the control structure.…”

“…In Ref. [23], an adaptive incremental backstepping sliding mode controller (AIBS-SMC) is designed to compensate for mismatched uncertainties in the control effectiveness matrix. In the research, the AIBS-SMC proved its excellent trajectorytracking performance and the stability of the closed-loop system.…”

“…The I&Ibased DOB is then combined with an adaptive backstepping control (ABSC). To effectively reduce design parameters and simplify the design process, a slack-variable approach [22][23][24][25] is adopted to deal with the underactuated system rather than the traditional hierarchical approach [26] or block-BSC approach [27]. The combined ABSC structure with the I&I-based DOB can effectively decouple the adaptive components and the slack variable update laws.…”