{"title":"Adaptive Super-Twisting Terminal Sliding Mode Observer-Based Stabilizer for Uncertain Nonlinear Time-Delay Systems With Unmatched Disturbances","authors":"Ming-Chang Pai","doi":"10.1002/acs.3994","DOIUrl":"https://doi.org/10.1002/acs.3994","url":null,"abstract":"<div>\u0000 \u0000 <p>The aim of this paper is to propose a novel adaptive observer-based stabilizer for a class of uncertain nonlinear time-delay systems subject to unmatched external disturbances. A terminal sliding mode controller based on an adaptive super-twisting terminal sliding mode observer is developed by using the linear matrix inequality (LMI) technique. Under the proposed scheme, the closed-loop system converges to origin in finite time as the matching condition is satisfied and converges to the uniform ultimate bound in the effects of unmatched external disturbances. The design of the observer and the stabilizer does not require the upper bound of uncertainties and external disturbances. The chattering phenomenon is eliminated. The observer and the stabilizer can be efficiently designed from the solutions of LMIs. Simulation results illustrate the effectiveness of the proposed control scheme.</p>\u0000 </div>","PeriodicalId":50347,"journal":{"name":"International Journal of Adaptive Control and Signal Processing","volume":"39 5","pages":"1091-1099"},"PeriodicalIF":3.9,"publicationDate":"2025-02-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143914741","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"计算机科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"ℒ\u0000 asso \u0000 \u0000 ℳ\u0000 𝒫\u0000 𝒞\u0000 -Based \u0000 \u0000 \u0000 \u0000 ℒ\u0000 \u0000 \u0000 1\u0000 \u0000 \u0000 Adaptive Control for Uncertain Euler–Lagrange Systems: Guaranteed Stability Robustness and Performance","authors":"Hossein Ahmadian, Heidar Ali Talebi, Iman Sharifi","doi":"10.1002/acs.3957","DOIUrl":"https://doi.org/10.1002/acs.3957","url":null,"abstract":"<div>\u0000 \u0000 <p>The challenge of assessing system states and considering the robot's physical limitations impedes the development of an <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <msub>\u0000 <mrow>\u0000 <mi>ℒ</mi>\u0000 </mrow>\u0000 <mrow>\u0000 <mn>1</mn>\u0000 </mrow>\u0000 </msub>\u0000 </mrow>\u0000 <annotation>$$ {mathcal{L}}_1 $$</annotation>\u0000 </semantics></math> adaptive controller for robotic systems. To solve this challenge, this study proposes an <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <msub>\u0000 <mrow>\u0000 <mi>ℒ</mi>\u0000 </mrow>\u0000 <mrow>\u0000 <mn>1</mn>\u0000 </mrow>\u0000 </msub>\u0000 </mrow>\u0000 <annotation>$$ {mathcal{L}}_1 $$</annotation>\u0000 </semantics></math> adaptive controller based on <i>ℒ</i>asso <span></span><math>\u0000 <mrow>\u0000 <mi>ℳ</mi>\u0000 <mi>𝒫</mi>\u0000 <mi>𝒞</mi>\u0000 </mrow></math> (<span></span><math>\u0000 <mrow>\u0000 <msub>\u0000 <mrow>\u0000 <mi>ℒ</mi>\u0000 </mrow>\u0000 <mrow>\u0000 <mn>1</mn>\u0000 </mrow>\u0000 </msub>\u0000 <mi>A</mi>\u0000 <mi>ℒ</mi>\u0000 <mi>ℳ</mi>\u0000 <mi>𝒫</mi>\u0000 <mi>𝒞</mi>\u0000 </mrow></math>) (for <i>Euler–Lagrange systems</i>) that combines the method by a <i>Barrier Lyapunov Function</i>(<span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mi>ℬ</mi>\u0000 <mi>ℒ</mi>\u0000 <mi>ℱ</mi>\u0000 </mrow>\u0000 <annotation>$$ mathit{mathcal{BLF}} $$</annotation>\u0000 </semantics></math>) and an <i>adaptive high-gain observer</i> (<span></span><math>\u0000 <mrow>\u0000 <mi>𝒜</mi>\u0000 <mi>ℋ</mi>\u0000 <mi>𝒢</mi>\u0000 <mi>𝒪</mi>\u0000 </mrow></math>). In the face of uncertainty, time delay, and inaccessibility of system states, the presented approach establishes a mechanism to compromise between <i>fast adaptation</i> and <i>robustness</i>. The <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mi>ℬ</mi>\u0000 <mi>ℒ</mi>\u0000 <mi>ℱ</mi>\u0000 </mrow>\u0000 <annotation>$$ mathit{mathcal{BLF}} $$</annotation>\u0000 </semantics></math> constrains the system's outputs and adjusts the observer gain to ensure the output estimation error stays within a predetermined range. Then, to increase the prediction accuracy, <i>ℒ</i>asso <span></span><math>\u0000 <mrow>\u0000 <mi>ℳ</mi>\u0000 ","PeriodicalId":50347,"journal":{"name":"International Journal of Adaptive Control and Signal Processing","volume":"39 5","pages":"842-861"},"PeriodicalIF":3.9,"publicationDate":"2025-02-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143914655","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"计算机科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}