**5. Conclusions**

In this paper, a distributed interval observer design methodology for linear fractionalorder MASs with nonlinearity was proposed. A Lyapunov method that is useful for observer and controller design was first introduced for general fractional-order systems. For MASs, graph theory was applied to fractional-order systems, and the strict LMI and an effective algorithm were presented for observer design. Lastly, an example was given to demonstrate the effectiveness of the proposed method. In the future, by using the *H*∞ technique, we aim to focus on research regarding the consensus control or formation control of fractional-order MASs.

**Author Contributions:** Conceptualization, H.Z. and J.H.; methodology, J.H.; software, H.Z.; validation, H.Z., J.H. and S.H.; formal analysis, H.Z.; investigation, S.H.; resources, H.Z.; data curation, H.Z.; writing—original draft preparation, H.Z.; writing—review and editing, H.Z.; visualization, H.Z.; supervision, J.H.; project administration, J.H.; funding acquisition, J.H. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research were funded by the Natural Science Foundation of Jiangsu province of China under grant BK2021-1309, and in part by the Open Fund for Jiangsu Key Laboratory of Advanced Manufacturing Technology under grant HGAMTL-2101 and by Undergraduate Training Program For Innovation and Entrepreneurship, Soochow University(202210285152Y).

**Institutional Review Board Statement:** Not applicable.

**Informed Consent Statement:** Not applicable.

**Data Availability Statement:** Not applicable.

**Acknowledgments:** we would like to express our great appreciation to the editors and reviewers.

**Conflicts of Interest:** The authors declare no conflict of interest.
