A Composite Position Control of Flexible Lower Limb Exoskeleton Based on Second-order Sliding Mode

A Composite Position Control of Flexible Lower Limb Exoskeleton Based on Second-order Sliding Mode | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article A Composite Position Control of Flexible Lower Limb Exoskeleton Based on Second-order Sliding Mode Zhenxing Sun, Jinghao Zhu, Shenghui Li This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-1542434/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 4 You are reading this latest preprint version Abstract Aiming at the problem that the trajectory tracking error of flexible lower limb exoskeleton robot is too large under the condition of external disturbance and parameters uncertainty, a composite position control method based on second-order sliding mode was proposed. Firstly, the flexible lower limb exoskeleton robot is modeled by Lagrange function. Secondly, considering that the system is affected not only by matched disturbance but also by unmatched disturbance, two finite time state observers are used to observe and compensate the two disturbances in real time. In the position control part, the super twisting algorithm is used to ensure the trajectory tracking error of knee joint converging to zero in finite time. Eventually, the stability of the proposed control strategy is proved by the Lyapunov function. The experimental results show that the proposed control strategy has more accurate trajectory tracking effect and robustness than the traditional PD control and sliding mode control, which indicates the superiority of the proposed control strategy. Flexible lower limb exoskeleton Matched disturbance Unmatched disturbance Super twisting algorithm Second order sliding mode control Full Text Cite Share Download PDF Status: Under Review Version 1 posted Reviews received at journal 24 Apr, 2022 Reviewers invited by journal 24 Apr, 2022 Editor assigned by journal 19 Apr, 2022 First submitted to journal 10 Apr, 2022 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-1542434","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":100972267,"identity":"72352321-3a94-4a35-a518-3eaf5f48a975","order_by":0,"name":"Zhenxing Sun","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA8ElEQVRIiWNgGAWjYHACNhDBw8DAfAzCZSdeC1saA0MCkGImUgtIlxlYCwMhLfKz2589+LjjsIw5/5pvDz7+2CbPx8zA+OFjDm4tBncOpBvOPJPGYznj7XbDGQm3DduYGZglZ27Do0Ui4Zg0b5sNj8GNs9ukeRJuMwK1sDHz4tEiPyOxTfpvmwRQy5lnIC32BLUw3Ehmk2YE2XK+hw2kJZGgFoMbaWySvW1pQFvYzCRnpN1ObmNmbMbrF/kZ6c8kfrYdtjc4f/iZxAeb27bz25sPfviIz2FwIJEAYzE2EKMeCPgPEKlwFIyCUTAKRhwAAKPOS92CuitgAAAAAElFTkSuQmCC","orcid":"https://orcid.org/0000-0002-6019-106X","institution":"Nanjing Tech University","correspondingAuthor":true,"submittingAuthor":false,"prefix":"","firstName":"Zhenxing","middleName":"","lastName":"Sun","suffix":""},{"id":100972268,"identity":"eb3b3861-0d5f-4b82-a9be-eba46010737d","order_by":1,"name":"Jinghao Zhu","email":"","orcid":"","institution":"Nanjing Tech University","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Jinghao","middleName":"","lastName":"Zhu","suffix":""},{"id":100972269,"identity":"e3d57f8d-d592-46ed-8e57-80bb2e999085","order_by":2,"name":"Shenghui Li","email":"","orcid":"","institution":"Nanjing University of Science and Technology Zijin College","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Shenghui","middleName":"","lastName":"Li","suffix":""}],"badges":[],"createdAt":"2022-04-10 09:38:38","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-1542434/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-1542434/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":20739773,"identity":"cd49876c-f4d5-4b6d-a7ed-b76652060bf0","added_by":"auto","created_at":"2022-04-25 17:25:54","extension":"pdf","order_by":1,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1130726,"visible":true,"origin":"","legend":"","description":"","filename":"ACompositePositionControlofFlexibleLowerLimb.pdf","url":"https://assets-eu.researchsquare.com/files/rs-1542434/v1_covered.pdf"}],"financialInterests":"","formattedTitle":"A Composite Position Control of Flexible Lower Limb Exoskeleton Based on Second-order Sliding Mode","fulltext":[{"header":"Full Text","content":"This preprint is available for \u003ca href='/article/rs-1542434/latest.pdf' target='_blank'\u003edownload as a PDF\u003c/a\u003e."}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":false,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":true,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":true,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"nonlinear-dynamics","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"nody","sideBox":"Learn more about [Nonlinear Dynamics](https://www.springer.com/journal/11071)","snPcode":"11071","submissionUrl":"https://submission.nature.com/new-submission/11071/3","title":"Nonlinear Dynamics","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"Flexible lower limb exoskeleton, Matched disturbance, Unmatched disturbance, Super twisting algorithm, Second order sliding mode control","lastPublishedDoi":"10.21203/rs.3.rs-1542434/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-1542434/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"Aiming at the problem that the trajectory tracking error of flexible lower limb exoskeleton robot is too large under the condition of external disturbance and parameters uncertainty, a composite position control method based on second-order sliding mode was proposed. Firstly, the flexible lower limb exoskeleton robot is modeled by Lagrange function. Secondly, considering that the system is affected not only by matched disturbance but also by unmatched disturbance, two finite time state observers are used to observe and compensate the two disturbances in real time. In the position control part, the super twisting algorithm is used to ensure the trajectory tracking error of knee joint converging to zero in finite time. Eventually, the stability of the proposed control strategy is proved by the Lyapunov function. The experimental results show that the proposed control strategy has more accurate trajectory tracking effect and robustness than the traditional PD control and sliding mode control, which indicates the superiority of the proposed control strategy.","manuscriptTitle":"A Composite Position Control of Flexible Lower Limb Exoskeleton Based on Second-order Sliding Mode","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2022-04-25 17:25:41","doi":"10.21203/rs.3.rs-1542434/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"editorInvitedReview","content":"","date":"2022-04-24T12:50:28+00:00","index":0,"fulltext":""},{"type":"reviewersInvited","content":"","date":"2022-04-24T12:45:00+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2022-04-19T08:44:11+00:00","index":"","fulltext":""},{"type":"submitted","content":"Nonlinear Dynamics","date":"2022-04-10T05:37:44+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"nonlinear-dynamics","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"nody","sideBox":"Learn more about [Nonlinear Dynamics](https://www.springer.com/journal/11071)","snPcode":"11071","submissionUrl":"https://submission.nature.com/new-submission/11071/3","title":"Nonlinear Dynamics","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"374b9a2e-1851-46c3-a23b-008e19a0fbae","owner":[],"postedDate":"April 25th, 2022","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"under-review","subjectAreas":[],"tags":[],"updatedAt":"2022-09-16T02:14:56+00:00","versionOfRecord":[],"versionCreatedAt":"2022-04-25 17:25:41","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-1542434","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-1542434","identity":"rs-1542434","version":["v1"]},"buildId":"7rjqhiLT3MXkJMwkYKINL","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}