Immersion and Invariance Adaptive Fault-Tolerant Attitude Control for a Coaxial Tilt-Rotor eVTOL Aircraft

Zheng Hou; Zongyang Lv; Yuhu Wu

Open Access Article

By Zheng Hou¹ , Zongyang Lv²^,* and Yuhu Wu¹

1 School of Control Science and Engineering, Dalian University of Technology, Dalian 116024, China

2 Department of Electrical and Computer Engineering, University of Alberta, Edmonton, AB T6G 1H9, Canada

* Authors to whom correspondence should be addressed.

Received: 18 September 2025

Revised: 13 January 2026

Accepted: 28 January 2026

Published: 16 March 2026

Abstract

This paper proposes an adaptive fault-tolerant attitude control strategy based on the Immersion and Invariance (I&I) methodology for a Coaxial Tilt-Rotor (CTR) eVTOL aircraft. The CTR-eVTOL, equipped with two pairs of CTR modules and a rear rotor, exhibiting strong nonlinearity, underactuated, and strong coupling characteristics, faces significant challenges in maintaining stable attitude control when subjected to a Loss Of Effectiveness (LOE) fault. To address this, the proposed Fault-Tolerant Control (FTC) strategy integrates the I&I adaptive methodology to compensate for the torque losses induced by the LOE fault. Specifically, an I&I-based adaptive update law is designed to estimate the unknown faulty coefficient. The closed-loop system's asymptotic stability is theoretically proven using the Lyapunov method and LaSalle's invariance theorem. Real ground bench experiments with comparative controllers validate the effectiveness and superiority of the proposed FTC strategy.

Keywords: fault-tolerant control; tilt-rotor eVTOL; immersion and invariance

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