{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,17]],"date-time":"2026-10-17T00:08:28Z","timestamp":1792195708232,"version":"4.4.0"},"reference-count":23,"publisher":"MDPI AG","issue":"7","license":[{"start":{"date-parts":[[2026,3,29]],"date-time":"2026-03-29T00:00:00Z","timestamp":1774742400000},"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":["52365039"],"award-info":[{"award-number":["52365039"]}],"id":[{"id":"10.13039\/501100001809","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>Lower-limb exoskeleton robots play a pivotal role in rehabilitation medicine and assistive augmentation, where precise dynamic modelling and trajectory tracking control are fundamental to effective assistance. Existing models predominantly focus on hip and knee rotational degrees of freedom, with insufficient attention to ankle dynamics and pelvic translation. To address these limitations, this paper establishes a sagittal-plane dynamic model comprising nine generalised coordinates, treating the human lower limb and exoskeleton as an integrated coupled system. A seven-segment kinematic model encompassing the trunk, bilateral thighs, shanks, and feet is constructed via a modified Denavit\u2013Hartenberg parameter method, and dynamic equations are derived using Lagrangian formulation. Three control strategies\u2014PD control, PD with gravity compensation, and the computed torque method\u2014are designed and evaluated through simulations using gait data from five subjects (two self-collected, three from a public dataset) acquired via Vicon motion capture. Results demonstrate that the computed torque method achieves a joint angle tracking root mean square error (RMSE) of 0.59\u00b0, representing an 86.3% improvement over conventional PD control, while maintaining a low control torque RMS of 4.44 N\u00b7m. The controller exhibits stable tracking performance across walking speeds of 0.4\u20131.45 m\/s, validating the effectiveness of the proposed model and control strategies.<\/jats:p>","DOI":"10.3390\/s26072124","type":"journal-article","created":{"date-parts":[[2026,3,30]],"date-time":"2026-03-30T08:22:36Z","timestamp":1774858956000},"page":"2124","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":3,"title":["Dynamic Modelling and Control Strategy Analysis of a Lower-Limb Exoskeleton"],"prefix":"10.3390","volume":"26","author":[{"given":"Huanrong","family":"Xiao","sequence":"first","affiliation":[{"name":"College of Mechanical Engineering, Xinjiang University, \u00dcr\u00fcmqi 830047, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Teng","family":"Ran","sequence":"additional","affiliation":[{"name":"College of Mechanical Engineering, Xinjiang University, \u00dcr\u00fcmqi 830047, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Afang","family":"Jin","sequence":"additional","affiliation":[{"name":"College of Mechanical Engineering, Xinjiang University, \u00dcr\u00fcmqi 830047, China"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2026,3,29]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"171","DOI":"10.1109\/TNSRE.2016.2521160","article-title":"State of the art and future directions for lower limb robotic exoskeletons","volume":"25","author":"Young","year":"2017","journal-title":"IEEE Trans. Neural Syst. Rehabil. Eng."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"74","DOI":"10.1186\/s10033-019-0389-8","article-title":"A review on lower limb rehabilitation exoskeleton robots","volume":"32","author":"Shi","year":"2019","journal-title":"Chin. J. Mech. Eng."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"120","DOI":"10.1016\/j.robot.2014.09.032","article-title":"Review of assistive strategies in powered lower-limb orthoses and exoskeletons","volume":"64","author":"Yan","year":"2015","journal-title":"Robot. Auton. Syst."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"22","DOI":"10.1186\/s10033-021-00537-8","article-title":"Control and implementation of 2-DOF lower limb exoskeleton experiment platform","volume":"34","author":"Chen","year":"2021","journal-title":"Chin. J. Mech. Eng."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"102699","DOI":"10.1016\/j.mechatronics.2021.102699","article-title":"Model identification and adaptive control of lower limb exoskeleton based on neighborhood field optimization","volume":"81","author":"Wu","year":"2022","journal-title":"Mechatronics"},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"26","DOI":"10.1186\/s10033-024-01008-6","article-title":"Model parameters identification and backstepping control of lower limb exoskeleton based on enhanced whale algorithm","volume":"37","author":"Shi","year":"2024","journal-title":"Chin. J. Mech. Eng."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"1213","DOI":"10.1007\/s11071-022-07876-8","article-title":"Modelling and analysis of coupling dynamics of swinging a lower limb exoskeleton","volume":"111","author":"Yan","year":"2022","journal-title":"Nonlinear Dyn."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"439","DOI":"10.1016\/j.apm.2021.12.007","article-title":"Human\u2013exoskeleton coupling dynamics in the swing of lower limb","volume":"104","author":"Yan","year":"2022","journal-title":"Appl. Math. Model."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"272","DOI":"10.1016\/S1672-6529(16)60397-9","article-title":"Development and analysis of an electrically actuated lower extremity assistive exoskeleton","volume":"14","author":"Long","year":"2017","journal-title":"J. Bionic Eng."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"226","DOI":"10.1007\/s40430-019-1729-4","article-title":"Biomimetic compliant lower limb exoskeleton (BioComEx) and its experimental evaluation","volume":"41","author":"Baser","year":"2019","journal-title":"J. Braz. Soc. Mech. Sci. Eng."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"1387","DOI":"10.1016\/S0021-9290(01)00105-1","article-title":"Contributions of the individual ankle plantar flexors to support, forward progression and swing initiation during walking","volume":"34","author":"Neptune","year":"2001","journal-title":"J. Biomech."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"543","DOI":"10.2106\/00004623-195335030-00003","article-title":"The major determinants in normal and pathological gait","volume":"35","author":"Saunders","year":"1953","journal-title":"J. Bone Jt. Surg. Am."},{"key":"ref_13","unstructured":"Kazerooni, H., Racine, J.L., Huang, L., and Steger, R. (2005, January 18\u201322). On the control of the Berkeley lower extremity exoskeleton (BLEEX). Proceedings of the IEEE International Conference on Robotics and Automation, Barcelona, Spain."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"410","DOI":"10.1109\/TNSRE.2007.903930","article-title":"Assessment of motion of a swing leg and gait rehabilitation with a gravity balancing exoskeleton","volume":"15","author":"Agrawal","year":"2007","journal-title":"IEEE Trans. Neural Syst. Rehabil. Eng."},{"key":"ref_15","unstructured":"Spong, M.W., Hutchinson, S., and Vidyasagar, M. (2020). Robot Modeling and Control, Wiley. [2nd ed.]."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"23","DOI":"10.1186\/s12984-023-01144-5","article-title":"Control strategies used in lower limb exoskeletons for gait rehabilitation after brain injury: A systematic review and analysis of clinical effectiveness","volume":"20","author":"Prinsen","year":"2023","journal-title":"J. NeuroEng. Rehabil."},{"key":"ref_17","doi-asserted-by":"crossref","unstructured":"Yu, X., Leto, L., and Bai, S. (2023). Design and gait control of an active lower limb exoskeleton for walking assistance. Machines, 11.","DOI":"10.3390\/machines11090864"},{"key":"ref_18","first-page":"155","article-title":"Design and experimental verification of hip exoskeleton with balance capacities for walking assistance","volume":"28","author":"Zhang","year":"2023","journal-title":"IEEE\/ASME Trans. Mechatron."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"37","DOI":"10.1186\/s10033-024-01025-5","article-title":"Neural network robust control based on computed torque for lower limb exoskeleton","volume":"37","author":"Han","year":"2024","journal-title":"Chin. J. Mech. Eng."},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1186\/1743-0003-12-1","article-title":"Control strategies for active lower extremity prosthetics and orthotics: A review","volume":"12","author":"Tucker","year":"2015","journal-title":"J. NeuroEng. Rehabil."},{"key":"ref_21","first-page":"3496","article-title":"Human-machine coupling dynamics and assistance performance analysis of an ankle exoskeleton","volume":"54","author":"Gao","year":"2022","journal-title":"Chin. J. Theor. Appl. Mech."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"20200487","DOI":"10.1098\/rsif.2020.0487","article-title":"Predicting walking response to ankle exoskeletons using data-driven models","volume":"17","author":"Rosenberg","year":"2020","journal-title":"J. R. Soc. Interface"},{"key":"ref_23","doi-asserted-by":"crossref","unstructured":"Winter, D.A. (2009). Biomechanics and Motor Control of Human Movement, Wiley. 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