{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,4,2]],"date-time":"2026-04-02T03:03:02Z","timestamp":1775098982807,"version":"3.50.1"},"reference-count":61,"publisher":"Frontiers Media SA","license":[{"start":{"date-parts":[[2023,12,6]],"date-time":"2023-12-06T00:00:00Z","timestamp":1701820800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100001691","name":"Japan Society for the Promotion of Science","doi-asserted-by":"publisher","id":[{"id":"10.13039\/501100001691","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":["frontiersin.org"],"crossmark-restriction":true},"short-container-title":["Front. Robot. AI"],"abstract":"<jats:p><jats:bold>Introduction:<\/jats:bold> Robotic exoskeletons are emerging technologies that have demonstrated their effectiveness in assisting with Activities of Daily Living. However, kinematic disparities between human and robotic joints can result in misalignment between humans and exoskeletons, leading to discomfort and potential user injuries.<\/jats:p><jats:p><jats:bold>Methods:<\/jats:bold> In this paper, we present an ergonomic knee exoskeleton based on a dual four-bar linkage mechanism powered by hydraulic artificial muscles for stair ascent assistance. The device comprises two asymmetric four-bar linkage mechanisms on the medial and lateral sides to accommodate the internal rotation of the knee and address the kinematic discrepancies between these sides. A genetic algorithm was employed to optimize the parameters of the four-bar linkage mechanism to minimize misalignment between human and exoskeleton knee joints. The proposed device was evaluated through two experiments. The first experiment measured the reduction in undesired load due to misalignment, while the second experiment evaluated the device\u2019s effectiveness in assisting stair ascent in a healthy subject.<\/jats:p><jats:p><jats:bold>Results:<\/jats:bold> The experimental results indicate that the proposed device has a significantly reduced undesired load compared to the traditional revolute joint, decreasing from 14.15\u00a0N and 18.32\u00a0N to 1.88\u00a0N and 1.07\u00a0N on the medial and lateral sides, respectively. Moreover, a substantial reduction in muscle activities during stair ascent was observed, with a 55.94% reduction in surface electromyography signal.<\/jats:p><jats:p><jats:bold>Discussion:<\/jats:bold> The reduced undesired load of the proposed dual four-bar linkage mechanism highlights the importance of the adopted asymmetrical design for reduced misalignment and increased comfort. Moreover, the proposed device was effective at reducing the effort required during stair ascent.<\/jats:p>","DOI":"10.3389\/frobt.2023.1285520","type":"journal-article","created":{"date-parts":[[2023,12,6]],"date-time":"2023-12-06T08:26:30Z","timestamp":1701851190000},"update-policy":"https:\/\/doi.org\/10.3389\/crossmark-policy","source":"Crossref","is-referenced-by-count":5,"title":["Ergonomic dual four-bar linkage knee exoskeleton for stair ascent assistance"],"prefix":"10.3389","volume":"10","author":[{"given":"Sarin","family":"Kittisares","sequence":"first","affiliation":[]},{"given":"Tohru","family":"Ide","sequence":"additional","affiliation":[]},{"given":"Hiroyuki","family":"Nabae","sequence":"additional","affiliation":[]},{"given":"Koichi","family":"Suzumori","sequence":"additional","affiliation":[]}],"member":"1965","published-online":{"date-parts":[[2023,12,6]]},"reference":[{"key":"B1","first-page":"539","article-title":"Test method for contact safety assessment of a wearable robot-analysis of load caused by a misalignment of the knee joint","volume-title":"2012 ieee ro-man: the 21st IEEE international symposium on robot and human interactive communication","author":"Akiyama","year":"2012"},{"key":"B2","first-page":"771","article-title":"Falls in the elderly: spectrum and prevention","volume":"57","author":"Al-Aama","year":"2011","journal-title":"Can. Fam. Physician"},{"key":"B3","doi-asserted-by":"publisher","first-page":"749","DOI":"10.2106\/00004623-198062050-00008","article-title":"A study of lower-limb mechanics during stair-climbing","volume":"62","author":"Andriacchi","year":"1980","journal-title":"JBJS"},{"key":"B4","doi-asserted-by":"crossref","first-page":"122","DOI":"10.1109\/AIM46487.2021.9517444","article-title":"Multi-objective optimization of force transmission quality and joint misalignment of a 5-bar knee exoskeleton","volume-title":"2021 IEEE\/ASME international conference on advanced intelligent mechatronics (AIM)","author":"Asker","year":"2021"},{"key":"B5","doi-asserted-by":"publisher","first-page":"371","DOI":"10.1080\/03093640601095842","article-title":"Development of a hinge compatible with the kinematics of the knee joint","volume":"31","author":"Bertomeu","year":"2007","journal-title":"Prosthetics Orthot. Int."},{"key":"B6","doi-asserted-by":"publisher","first-page":"13","DOI":"10.1186\/s12984-022-00990-z","article-title":"Assessing effects of exoskeleton misalignment on knee joint load during swing using an instrumented leg simulator","volume":"19","author":"Bessler-Etten","year":"2022","journal-title":"J. neuroengineering rehabilitation"},{"key":"B7","first-page":"409","article-title":"Variations of femoral condyle shape","volume":"29","author":"Bi\u0161\u010devi\u0107","year":"2005","journal-title":"Coll. Antropol."},{"key":"B8","doi-asserted-by":"publisher","first-page":"25","DOI":"10.1097\/01.blo.0000063564.90853.ed","article-title":"Kinematics of the human knee using an open chain cadaver model","volume":"410","author":"Blaha","year":"2003","journal-title":"Clin. Orthop. Relat. Research\u00ae"},{"key":"B9","doi-asserted-by":"publisher","first-page":"e4","DOI":"10.1017\/wtc.2022.1","article-title":"Evaluation of the power deficit of elderly people during stair negotiation: which joints should be assisted at least by an exoskeleton and with what amount?","volume":"3","author":"B\u00f6hme","year":"2022","journal-title":"Wearable Technol."},{"key":"B10","volume-title":"National trauma registry 2011 report: hospitalizations for major injury in Canada, 2008\u20132009 data","year":"2011"},{"key":"B11","first-page":"996","article-title":"AssistOn-Knee: a self-aligning knee exoskeleton","volume-title":"IEEE international conference on intelligent robots and systems","author":"Celebi","year":"2013"},{"key":"B12","first-page":"286","article-title":"The comparison and combination of genetic and gradient descent learning in recurrent neural networks: an application to speech phoneme classification","volume-title":"Artificial intelligence and pattern recognition (citeseer)","author":"Chandra","year":"2007"},{"key":"B13","doi-asserted-by":"crossref","first-page":"1458","DOI":"10.1109\/AIM.2013.6584300","article-title":"Preliminary evaluation of a lower-limb exoskeleton-stair climbing","volume-title":"2013 IEEE\/ASME international conference on advanced intelligent mechatronics","author":"Chandrapal","year":"2013"},{"key":"B14","doi-asserted-by":"publisher","first-page":"1223","DOI":"10.1016\/0021-9290(95)00178-6","article-title":"Adjustments to zatsiorsky-seluyanov\u2019s segment inertia parameters","volume":"29","author":"De Leva","year":"1996","journal-title":"J. biomechanics"},{"key":"B15","doi-asserted-by":"publisher","first-page":"102","DOI":"10.1016\/j.clinbiomech.2015.12.006","article-title":"In-vivo analysis of flexion axes of the knee: femoral condylar motion during dynamic knee flexion","volume":"32","author":"Feng","year":"2016","journal-title":"Clin. Biomech."},{"key":"B16","doi-asserted-by":"publisher","first-page":"853","DOI":"10.1115\/1.4014513","article-title":"Approximate synthesis of four-bar linkages","volume":"77","author":"Freudenstein","year":"1955","journal-title":"Trans. Am. Soc. Mech. Eng."},{"key":"B17","doi-asserted-by":"publisher","first-page":"065124","DOI":"10.1063\/5.0053899","article-title":"Design and optimization of exoskeleton structure of lower limb knee joint based on cross four-bar linkage","volume":"11","author":"Gao","year":"2021","journal-title":"AIP Adv."},{"key":"B18","doi-asserted-by":"publisher","first-page":"M453","DOI":"10.1093\/gerona\/58.5.m453","article-title":"Old adults perform activities of daily living near their maximal capabilities","volume":"58","author":"Hortob\u00e1gyi","year":"2003","journal-title":"Journals Gerontology Ser. A Biol. Sci. Med. Sci."},{"key":"B19","doi-asserted-by":"publisher","first-page":"176","DOI":"10.1016\/J.RBMRET.2004.03.003","article-title":"A model of exo-prosthesis of the knee optimized with respect to the physiological motion of condyles","volume":"25","author":"Karami","year":"2004","journal-title":"ITBM-RBM"},{"key":"B20","doi-asserted-by":"publisher","first-page":"112","DOI":"10.5772\/60782","article-title":"Design of a knee exoskeleton using foot pressure and knee torque sensors","volume":"12","author":"Kim","year":"2015","journal-title":"Int. J. Adv. Robotic Syst."},{"key":"B21","doi-asserted-by":"publisher","first-page":"102822","DOI":"10.1016\/j.mechatronics.2022.102822","article-title":"Alternating pressure control system for hydraulic robots","volume":"85","author":"Kittisares","year":"2022","journal-title":"Mechatronics"},{"key":"B61","doi-asserted-by":"crossref","first-page":"103068","DOI":"10.1016\/j.mechatronics.2023.103068","article-title":"Open-looped pressure and volume control of multi-degree-of-freedom hydraulic systems","volume":"95","author":"Kittisares","year":"2023","journal-title":"Mechatronics"},{"key":"B22","doi-asserted-by":"publisher","first-page":"16","DOI":"10.1186\/s40648-020-00165-2","article-title":"Design of knee support device based on four-bar linkage and hydraulic artificial muscle","volume":"7","author":"Kittisares","year":"2020","journal-title":"Robomech J."},{"key":"B23","doi-asserted-by":"publisher","first-page":"1269","DOI":"10.1016\/J.JBIOMECH.2008.01.013","article-title":"The knee joint center of rotation is predominantly on the lateral side during normal walking","volume":"41","author":"Koo","year":"2008","journal-title":"J. Biomechanics"},{"key":"B24","doi-asserted-by":"publisher","first-page":"487","DOI":"10.1016\/0021-9290(85)90663-3","article-title":"Geometry and motion of the knee for implant and orthotic design","volume":"18","author":"Kurosawa","year":"1985","journal-title":"J. biomechanics"},{"key":"B25","doi-asserted-by":"publisher","first-page":"66","DOI":"10.1016\/j.sna.2017.04.047","article-title":"Design of thin mckibben muscle and multifilament structure","volume":"261","author":"Kurumaya","year":"2017","journal-title":"Sensors Actuators A Phys."},{"key":"B26","doi-asserted-by":"publisher","first-page":"678","DOI":"10.1111\/j.1600-0838.2008.00845.x","article-title":"Biomechanical determinants of maximal stair climbing capacity in healthy elderly women","volume":"19","author":"Larsen","year":"2009","journal-title":"Scand. J. Med. Sci. sports"},{"key":"B27","doi-asserted-by":"publisher","first-page":"1231","DOI":"10.1016\/j.jbiomech.2010.02.001","article-title":"Kinematic and dynamic analysis of an anatomically based knee joint","volume":"43","author":"Lee","year":"2010","journal-title":"J. biomechanics"},{"key":"B28","doi-asserted-by":"publisher","first-page":"91614","DOI":"10.1109\/access.2021.3091649","article-title":"Weight distribution of a knee exoskeleton influences muscle activities during movements","volume":"9","author":"Liu","year":"2021","journal-title":"IEEE Access"},{"key":"B29","doi-asserted-by":"publisher","first-page":"113168","DOI":"10.1016\/j.sna.2021.113168","article-title":"Bidirectional electrohydrodynamic pump with high symmetrical performance and its application to a tube actuator","volume":"332","author":"Mao","year":"2021","journal-title":"Sensors Actuators A Phys."},{"key":"B30","doi-asserted-by":"publisher","first-page":"733","DOI":"10.1016\/0021-9290(88)90282-5","article-title":"An integrated biomechanical analysis of normal stair ascent and descent","volume":"21","author":"McFadyen","year":"1988","journal-title":"J. biomechanics"},{"key":"B31","doi-asserted-by":"publisher","first-page":"233","DOI":"10.1163\/016918609x12586209967366","article-title":"Very high force hydraulic mckibben artificial muscle with a p-phenylene-2, 6-benzobisoxazole cord sleeve","volume":"24","author":"Mori","year":"2010","journal-title":"Adv. Robot."},{"key":"B32","doi-asserted-by":"publisher","first-page":"511","DOI":"10.1080\/01691864.2018.1464946","article-title":"A proposal of a new rotational-compliant joint with oil-hydraulic mckibben artificial muscles","volume":"32","author":"Morita","year":"2018","journal-title":"Adv. Robot."},{"key":"B33","first-page":"V001T30A002","article-title":"Optimization and design principles of a minimal-weight, wearable hydraulic power supply","volume-title":"Dynamic systems and control conference","author":"Nath","year":"2017"},{"key":"B34","doi-asserted-by":"publisher","first-page":"36","DOI":"10.1080\/10400435.1993.10132205","article-title":"Predictors of assistive technology abandonment","volume":"5","author":"Phillips","year":"1993","journal-title":"Assist. Technol."},{"key":"B35","doi-asserted-by":"publisher","first-page":"S3","DOI":"10.1007\/pl00003679","article-title":"The shapes and relative movements of the femur and tibia at the knee","volume":"29","author":"Pinskerova","year":"2000","journal-title":"Orthopade"},{"key":"B36","doi-asserted-by":"crossref","DOI":"10.1002\/9780470987667","volume-title":"Wearable robots: biomechatronic exoskeletons","author":"Pons","year":"2008"},{"key":"B37","doi-asserted-by":"publisher","first-page":"203","DOI":"10.1016\/j.clinbiomech.2006.09.010","article-title":"Hip, knee, ankle kinematics and kinetics during stair ascent and descent in healthy young individuals","volume":"22","author":"Protopapadaki","year":"2007","journal-title":"Clin. Biomech."},{"key":"B38","doi-asserted-by":"publisher","first-page":"159","DOI":"10.3109\/03093649409164401","article-title":"Four-bar linkage prosthetic knee mechanisms: kinematics, alignment and prescription criteria","volume":"18","author":"Radcliffe","year":"1994","journal-title":"Prosthetics Orthot. Int."},{"key":"B39","doi-asserted-by":"publisher","first-page":"e57","DOI":"10.1016\/j.jelekin.2007.09.009","article-title":"Older adults employ alternative strategies to operate within their maximum capabilities when ascending stairs","volume":"19","author":"Reeves","year":"2009","journal-title":"J. Electromyogr. Kinesiol."},{"key":"B40","doi-asserted-by":"publisher","first-page":"2005","DOI":"10.1249\/mss.0b013e31814538c8","article-title":"Knee biomechanics of alternate stair ambulation patterns","volume":"39","author":"Reid","year":"2007","journal-title":"Med. Sci. sports Exerc."},{"key":"B41","doi-asserted-by":"publisher","first-page":"32","DOI":"10.1016\/s0966-6362(01)00162-x","article-title":"Stair ascent and descent at different inclinations","volume":"15","author":"Riener","year":"2002","journal-title":"Gait posture"},{"key":"B42","doi-asserted-by":"publisher","first-page":"649","DOI":"10.1249\/01.mss.0000159007.56083.96","article-title":"Manipulations of leg mass and moment of inertia: effects on energy cost of walking","volume":"37","author":"Royer","year":"2005","journal-title":"Med. Sci. sports Exerc."},{"key":"B43","doi-asserted-by":"publisher","first-page":"906","DOI":"10.1016\/s0268-0033(01)00085-7","article-title":"Lower extremity kinetics during stair ambulation in patients with and without patellofemoral pain","volume":"16","author":"Salsich","year":"2001","journal-title":"Clin. Biomech."},{"key":"B44","doi-asserted-by":"publisher","first-page":"248","DOI":"10.1109\/tmrb.2020.2981951","article-title":"Design, development, and validation of a self-aligning mechanism for high-torque powered knee exoskeletons","volume":"2","author":"Sarkisian","year":"2020","journal-title":"IEEE Trans. Med. Robotics Bionics"},{"key":"B45","first-page":"94","article-title":"The characteristics of the mckibben artificial muscle","volume-title":"The application of external power in prosthetics and orthotics","author":"Schulte","year":"1961"},{"key":"B46","doi-asserted-by":"crossref","first-page":"1230","DOI":"10.1109\/SMC42975.2020.9283152","article-title":"Review and assessment of walking assist exoskeleton knee joints","volume-title":"2020 IEEE international conference on systems, man, and cybernetics (SMC)","author":"S\u00e9guin","year":"2020"},{"key":"B47","doi-asserted-by":"publisher","first-page":"6","DOI":"10.33696\/rehabilitation.5.034","article-title":"Kinematic and kinetic assessment of a novel polycentric knee joint for powered walking assist exoskeletons","volume":"5","author":"S\u00e9guin","year":"2023","journal-title":"J. Phys. Med. Rehabilitation"},{"key":"B48","doi-asserted-by":"publisher","first-page":"52","DOI":"10.1016\/j.clinbiomech.2007.08.013","article-title":"The effect of functional knee brace design and hinge misalignment on lower limb joint mechanics","volume":"23","author":"Singer","year":"2008","journal-title":"Clin. Biomech."},{"key":"B49","doi-asserted-by":"publisher","first-page":"567","DOI":"10.1111\/j.1532-5415.2000.tb05006.x","article-title":"Stair negotiation in older people: a review","volume":"48","author":"Startzell","year":"2000","journal-title":"J. Am. Geriatrics Soc."},{"key":"B50","doi-asserted-by":"publisher","first-page":"539","DOI":"10.1109\/TRO.2009.2019788","article-title":"A highly backdrivable, lightweight knee actuator for investigating gait in stroke","volume":"25","author":"Sulzer","year":"2009","journal-title":"IEEE Trans. Robotics"},{"key":"B51","doi-asserted-by":"crossref","first-page":"2423","DOI":"10.1109\/IROS.2011.6094633","article-title":"Study on a practical robotic follower to support home oxygen therapy patients-development and control of a mobile platform","volume-title":"2011 IEEE\/RSJ international conference on intelligent robots and systems","author":"Tani","year":"2011"},{"key":"B52","doi-asserted-by":"publisher","first-page":"225","DOI":"10.1177\/1045389x11435435","article-title":"Modelling of the mckibben artificial muscle: a review","volume":"23","author":"Tondu","year":"2012","journal-title":"J. Intelligent Material Syst. Struct."},{"key":"B53","doi-asserted-by":"crossref","DOI":"10.1093\/oso\/9780198570271.001.0001","volume-title":"The physics of rubber elasticity","author":"Treloar","year":"2005"},{"key":"B54","doi-asserted-by":"publisher","first-page":"100","DOI":"10.1016\/j.apmr.2007.08.129","article-title":"Self-reported difficulty in climbing up or down stairs in nondisabled elderly","volume":"89","author":"Verghese","year":"2008","journal-title":"Archives Phys. Med. rehabilitation"},{"key":"B55","doi-asserted-by":"publisher","first-page":"4265","DOI":"10.1109\/LRA.2018.2864352","article-title":"Comfort-centered design of a lightweight and backdrivable knee exoskeleton","volume":"3","author":"Wang","year":"2018","journal-title":"IEEE Robotics Automation Lett."},{"key":"B56","doi-asserted-by":"publisher","first-page":"1","DOI":"10.1155\/2021\/8833461","article-title":"Lower-limb-assisting robotic exoskeleton reduces energy consumption in healthy young persons during stair climbing","volume":"2021","author":"Woo","year":"2021","journal-title":"Appl. Bionics Biomechanics"},{"key":"B57","volume-title":"Kinetics of human motion","author":"Zatsiorsky","year":"2002"},{"key":"B58","doi-asserted-by":"publisher","first-page":"125","DOI":"10.1243\/pime_proc_1992_206_280_02","article-title":"A model of human knee ligaments in the sagittal plane: Part 1: response to passive flexion","volume":"206","author":"Zavatsky","year":"1992","journal-title":"Proc. Institution Mech. Eng. Part H J. Eng. Med."},{"key":"B59","doi-asserted-by":"crossref","first-page":"555","DOI":"10.1109\/ROBIO55434.2022.10011948","article-title":"Design and optimization of 2dof humanoid dual cross four-bar mechanism for knee joint of an exoskeleton","volume-title":"2022 IEEE international conference on robotics and biomimetics (ROBIO)","author":"Zeng","year":"2022"},{"key":"B60","doi-asserted-by":"publisher","first-page":"103394","DOI":"10.1016\/j.robot.2019.103394","article-title":"Assistive devices of human knee joint: a review","volume":"125","author":"Zhang","year":"2020","journal-title":"Robotics Aut. Syst."}],"container-title":["Frontiers in Robotics and AI"],"original-title":[],"link":[{"URL":"https:\/\/www.frontiersin.org\/articles\/10.3389\/frobt.2023.1285520\/full","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2023,12,6]],"date-time":"2023-12-06T08:26:42Z","timestamp":1701851202000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.frontiersin.org\/articles\/10.3389\/frobt.2023.1285520\/full"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2023,12,6]]},"references-count":61,"alternative-id":["10.3389\/frobt.2023.1285520"],"URL":"https:\/\/doi.org\/10.3389\/frobt.2023.1285520","relation":{},"ISSN":["2296-9144"],"issn-type":[{"value":"2296-9144","type":"electronic"}],"subject":[],"published":{"date-parts":[[2023,12,6]]},"article-number":"1285520"}}