{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,1,18]],"date-time":"2026-01-18T13:40:41Z","timestamp":1768743641915,"version":"3.49.0"},"reference-count":50,"publisher":"Emerald","issue":"3","license":[{"start":{"date-parts":[[2017,5,15]],"date-time":"2017-05-15T00:00:00Z","timestamp":1494806400000},"content-version":"tdm","delay-in-days":0,"URL":"https:\/\/www.emerald.com\/insight\/site-policies"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["IR"],"published-print":{"date-parts":[[2017,5,15]]},"abstract":"<jats:sec>\n<jats:title content-type=\"abstract-subheading\">Purpose<\/jats:title>\n<jats:p>This paper aims to overcome some of the practical difficulties in assistive control of exoskeletons by developing a new assistive algorithm, called output feedback assistive control (OFAC) method. This method does not require feedbacks from force, electromyography (EMG) or acceleration signals or even their estimated values.<\/jats:p>\n<\/jats:sec>\n<jats:sec>\n<jats:title content-type=\"abstract-subheading\">Design\/methodology\/approach<\/jats:title>\n<jats:p>The presented controller uses feedbacks from position and velocity of the output link of series elastic actuators (SEAs) to increase the apparent integral admittance of the assisted systems. Optimal controller coefficients are obtained by maximizing the assistance ratio subjected to constraints of stability, coupled stability and a newly defined comfort measure.<\/jats:p>\n<\/jats:sec>\n<jats:sec>\n<jats:title content-type=\"abstract-subheading\">Findings<\/jats:title>\n<jats:p>The results confirm the effectiveness of using the inherent properties of SEAs for removing the need for extra controversial sensors in assistive control of 1 degree of freedom (1-DOF) SEA powered exoskeletons. The results also clearly indicate the successful performance of the OFAC method in reducing the external forces required for moving the assisted systems.<\/jats:p>\n<\/jats:sec>\n<jats:sec>\n<jats:title content-type=\"abstract-subheading\">Practical implications<\/jats:title>\n<jats:p>As the provided experiments indicate, the proposed method can be easily applied to single DOF compliantly actuated exoskeletons to provide a more reliable assistance with lower costs. This is achieved by removing the need for extra controversial sensors.<\/jats:p>\n<\/jats:sec>\n<jats:sec>\n<jats:title content-type=\"abstract-subheading\">Originality\/value<\/jats:title>\n<jats:p>This paper proposes a novel assistive controller for SEA-powered exoskeletons with a simple model-free structure and independent of any information about interaction forces and future paths of the system. It also removes the requirement for the extra sensors and transforms the assistive control of the compliantly actuated systems into a simpler problem of position control of the SEA motor.<\/jats:p>\n<\/jats:sec>","DOI":"10.1108\/ir-08-2016-0214","type":"journal-article","created":{"date-parts":[[2017,5,24]],"date-time":"2017-05-24T07:13:26Z","timestamp":1495610006000},"page":"275-287","source":"Crossref","is-referenced-by-count":14,"title":["Output feedback assistive control of single-DOF SEA powered exoskeletons"],"prefix":"10.1108","volume":"44","author":[{"given":"Iman","family":"Kardan","sequence":"first","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Alireza","family":"Akbarzadeh","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"140","reference":[{"key":"key2020120715531033900_ref001","first-page":"188","article-title":"Active-impedance control of a lower-limb assistive exoskeleton","year":"2007"},{"issue":"4","key":"key2020120715531033900_ref002","doi-asserted-by":"crossref","first-page":"486","DOI":"10.1177\/0278364910385730","article-title":"Design of an active one-degree-of-freedom lower-limb exoskeleton with inertia compensation","volume":"30","year":"2011","journal-title":"The International Journal of Robotics Research"},{"issue":"1","key":"key2020120715531033900_ref003","doi-asserted-by":"crossref","first-page":"68","DOI":"10.1109\/TNSRE.2011.2176960","article-title":"Inertia compensation control of a one-degree-of-freedom exoskeleton for lower-limb assistance: initial experiments","volume":"20","year":"2012","journal-title":"IEEE Transactions on Neural Systems and Rehabilitation Engineering"},{"issue":"5","key":"key2020120715531033900_ref004","doi-asserted-by":"crossref","first-page":"051013","DOI":"10.1115\/1.4029077","article-title":"Transparency improvement by external force estimation in a time-delayed nonlinear bilateral Teleoperation system","volume":"137","year":"2015","journal-title":"Journal of Dynamic Systems, Measurement, and Control"},{"issue":"5","key":"key2020120715531033900_ref005","doi-asserted-by":"crossref","first-page":"421","DOI":"10.1108\/01439910910980141","article-title":"Exoskeletons and robotic prosthetics: a review of recent developments","volume":"36","year":"2009","journal-title":"Industrial Robot: An International Journal"},{"issue":"6","key":"key2020120715531033900_ref006","doi-asserted-by":"crossref","first-page":"518","DOI":"10.1108\/IR-06-2014-0350","article-title":"ARES, a variable stiffness actuator with embedded force sensor for the ATLAS exoskeleton","volume":"41","year":"2014","journal-title":"Industrial Robot: An International Journal"},{"issue":"6","key":"key2020120715531033900_ref007","doi-asserted-by":"crossref","first-page":"881","DOI":"10.1115\/1.1634284","article-title":"Improving elbow torque output of stroke patients with assistive torque controlled by EMG signals","volume":"125","year":"2003","journal-title":"Journal of Biomechanical Engineering"},{"key":"key2020120715531033900_ref008","doi-asserted-by":"crossref","unstructured":"Colgate, J.E. 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