Anti-Disturbance for ST-VTOL UAV via Sliding Mode Control with Enhanced Observer

Jiahui Zhang; Jinwu Xiang; Daochun Li; Gang Yang; Weicheng Di; Ligang Zhang; Zhan Tu

doi:10.3390/drones9120843

journal article Open Access Dec 08, 2025

Anti-Disturbance for ST-VTOL UAV via Sliding Mode Control with Enhanced Observer

Jiahui Zhang

Jinwu Xiang Daochun Li Gang Yang

Weicheng Di Ligang Zhang

Zhan Tu

Drones Vol. 9 No. 12 pp. 843 · MDPI AG

View at Publisher Save 10.3390/drones9120843

Abstract

As a classical disturbance observation method, the extended state observer (ESO) is commonly used in controllers for disturbance estimation and feedback control. However, the ESO relies mainly on input–output signals and does not fully utilize information from system derivatives and the system’s dynamic structure. This underuse limits its effectiveness for vertical take-off and landing (VTOL) uncrewed aerial vehicles (UAVs). This limitation is especially problematic in small tailless VTOL UAVs (ST-VTOL UAVs). While these UAVs can switch modes and operate in confined spaces, they are highly susceptible to disturbances such as wind. To address this issue, this paper applies a novel disturbance rejection controller to an ST-VTOL UAV. Specifically, the controller replaces the traditional linear ESO with an enhanced state compensation function observer (SCFO) and integrates it with an equivalent sliding mode controller (ESMC). Simulation results demonstrate that the SCFO achieves substantially higher disturbance-estimation accuracy than both the classical ESO and its fal–function–enhanced variant. Flight experiments on the ST-VTOL UAV confirm that the proposed method reduces tracking error compared with a conventional PID controller and maintains stable hovering under external disturbances.

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References

Details

Published: Dec 08, 2025
Vol/Issue: 9(12)
Pages: 843
License: View

Authors

J

Jiahui Zhang

School of Aeronautic Science and Engineering, Beihang University, Beijing 100191, China

J

Jinwu Xiang

Tianmushan Laboratory, Hangzhou 310023, China

D

Daochun Li

School of Aeronautic Science and Engineering, Beihang University, Beijing 100191, China

G

Gang Yang

Institute of Unmanned System, Beihang University, Beijing 100191, China

W

Weicheng Di

School of Aeronautic Science and Engineering, Beihang University, Beijing 100191, China

L

Ligang Zhang

Institute of Unmanned System, Beihang University, Beijing 100191, China

Z

Zhan Tu

Institute of Unmanned System, Beihang University, Beijing 100191, China

Funding

Fundamental Research Funds for the Central Universities

Yunnan Science and Technology Projects Award: 202505AT350001

Reward Funds for Research Project of Tianmushan Laboratory Award: TK-2024-D-010

Cite This Article

Jiahui Zhang, Jinwu Xiang, Daochun Li, et al. (2025). Anti-Disturbance for ST-VTOL UAV via Sliding Mode Control with Enhanced Observer. Drones, 9(12), 843. https://doi.org/10.3390/drones9120843

Anti-Disturbance for ST-VTOL UAV via Sliding Mode Control with Enhanced Observer

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