{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,8,19]],"date-time":"2026-08-19T19:26:04Z","timestamp":1787167564857,"version":"3.56.0"},"reference-count":32,"publisher":"MDPI AG","issue":"1","license":[{"start":{"date-parts":[[2022,12,20]],"date-time":"2022-12-20T00:00:00Z","timestamp":1671494400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100001809","name":"National Natural Science Foundation of China","doi-asserted-by":"publisher","award":["62161003"],"award-info":[{"award-number":["62161003"]}],"id":[{"id":"10.13039\/501100001809","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100001809","name":"National Natural Science Foundation of China","doi-asserted-by":"publisher","award":["20210104"],"award-info":[{"award-number":["20210104"]}],"id":[{"id":"10.13039\/501100001809","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100001809","name":"National Natural Science Foundation of China","doi-asserted-by":"publisher","award":["2021AAF0103"],"award-info":[{"award-number":["2021AAF0103"]}],"id":[{"id":"10.13039\/501100001809","id-type":"DOI","asserted-by":"publisher"}]},{"name":"the Science and Technology Association Projects of Liuzhou","award":["62161003"],"award-info":[{"award-number":["62161003"]}]},{"name":"the Science and Technology Association Projects of Liuzhou","award":["20210104"],"award-info":[{"award-number":["20210104"]}]},{"name":"the Science and Technology Association Projects of Liuzhou","award":["2021AAF0103"],"award-info":[{"award-number":["2021AAF0103"]}]},{"name":"the Science and Technology Plan Projects of Liuzhou","award":["62161003"],"award-info":[{"award-number":["62161003"]}]},{"name":"the Science and Technology Plan Projects of Liuzhou","award":["20210104"],"award-info":[{"award-number":["20210104"]}]},{"name":"the Science and Technology Plan Projects of Liuzhou","award":["2021AAF0103"],"award-info":[{"award-number":["2021AAF0103"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>In this paper, the problem of actuator and sensor faults of a quadrotor unmanned aerial vehicle (QUAV) system is studied. In the system fault model, time delay, nonlinear term, and disturbances of QUAV during the flight are considered. A fault estimation algorithm based on an intermediate observer is proposed. To deal with a single actuator fault, an intermediate variable is introduced, and the intermediate observer is designed for the system to estimate fault. For simultaneous actuator and sensor faults, the system is first augmented, and then two intermediate variables are introduced, and an intermediate observer is designed for the augmented system to estimate the system state, faults, and disturbances. The Lyapunov\u2013Krasovskii functional is used to prove that the estimation error system is uniformly eventually bounded. The simulation results verify the feasibility and effectiveness of the proposed fault estimation method.<\/jats:p>","DOI":"10.3390\/s23010034","type":"journal-article","created":{"date-parts":[[2022,12,21]],"date-time":"2022-12-21T02:31:33Z","timestamp":1671589893000},"page":"34","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":13,"title":["Fault Estimation Method for Nonlinear Time-Delay System Based on Intermediate Observer-Application on Quadrotor Unmanned Aerial Vehicle"],"prefix":"10.3390","volume":"23","author":[{"given":"Qingnan","family":"Huang","sequence":"first","affiliation":[{"name":"School of Automation, Guangxi University of Science and Technology, Liuzhou 545006, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Jingru","family":"Qi","sequence":"additional","affiliation":[{"name":"School of Automation, Guangxi University of Science and Technology, Liuzhou 545006, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Xisheng","family":"Dai","sequence":"additional","affiliation":[{"name":"School of Automation, Guangxi University of Science and Technology, Liuzhou 545006, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Qiqi","family":"Wu","sequence":"additional","affiliation":[{"name":"School of Automation, Guangxi University of Science and Technology, Liuzhou 545006, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Xianming","family":"Xie","sequence":"additional","affiliation":[{"name":"School of Automation, Guangxi University of Science and Technology, Liuzhou 545006, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Enze","family":"Zhang","sequence":"additional","affiliation":[{"name":"School of Automation, Guangxi University of Science and Technology, Liuzhou 545006, China"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2022,12,20]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"2396","DOI":"10.1016\/j.jfranklin.2013.01.009","article-title":"Development of advanced FDD and FTC techniques with application to an unmanned quadrotor helicopter testbed","volume":"350","author":"Zhang","year":"2013","journal-title":"J. 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