{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,4,15]],"date-time":"2026-04-15T01:27:57Z","timestamp":1776216477441,"version":"3.50.1"},"reference-count":42,"publisher":"MDPI AG","issue":"12","license":[{"start":{"date-parts":[[2021,6,11]],"date-time":"2021-06-11T00:00:00Z","timestamp":1623369600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>This paper proposes a device that can change the payload of an unpowered lower-limb exoskeleton supporting the weights of humans and loads. Our previous exoskeletons used a cam\u2013follower structure with a spring applied to the hip joint. This exoskeleton showed satisfying performance within the payload; however, the performance decreased when the payload was exceeded. Therefore, a payload adjustment device that can adjust the wearer\u2019s required torque by easily applying it to the cam\u2013follower structure was developed. An exoskeleton dynamic equation that can calculate a person\u2019s required joint torque given the required payload and the wearer\u2019s posture was derived. This dynamic equation provides a guideline for designing a device that can adjust the allowable joint torque range of an unpowered exoskeleton. In the Adams simulation environment, the payload adjustment device is applied to the cam\u2013follower structure to show that the payload of the exoskeleton can be changed. User convenience and mass production were taken into account in the design of this device. This payload adjustment device should flexibly change the payload of the level desired by the wearer because it can quickly change the payload of the exoskeleton.<\/jats:p>","DOI":"10.3390\/s21124037","type":"journal-article","created":{"date-parts":[[2021,6,14]],"date-time":"2021-06-14T22:25:46Z","timestamp":1623709546000},"page":"4037","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":7,"title":["Design of a Payload Adjustment Device for an Unpowered Lower-Limb Exoskeleton"],"prefix":"10.3390","volume":"21","author":[{"given":"Junghwan","family":"Yun","sequence":"first","affiliation":[{"name":"PCO Nhac Ltd., Kyungpook National University, Daegu 41566, Korea"}]},{"given":"Ohhyun","family":"Kang","sequence":"additional","affiliation":[{"name":"PCO Nhac Ltd., Kyungpook National University, Daegu 41566, Korea"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-7415-645X","authenticated-orcid":false,"given":"Hyun-Min","family":"Joe","sequence":"additional","affiliation":[{"name":"Humanoid Robotics Laboratory, Department of Artificial Intelligence, Department of Robot & Smart System Engineering, Kyungpook National University, Daegu 41566, Korea"}]}],"member":"1968","published-online":{"date-parts":[[2021,6,11]]},"reference":[{"key":"ref_1","first-page":"1599","article-title":"A review of exoskeleton-type systems and their key technologies","volume":"222","author":"Yang","year":"2008","journal-title":"Proc. Inst. Mech. Eng. H"},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"160","DOI":"10.1017\/S0266462317000460","article-title":"What are user perspectives of exoskeleton technology? A literature review","volume":"33","author":"Hill","year":"2017","journal-title":"Int. J. Technol. Assess. Health Care"},{"key":"ref_3","first-page":"520","article-title":"Lower extremity exoskeleton: Review and challenges surrounding the technology and its role in rehabilitation of lower limbs","volume":"7","author":"Hong","year":"2013","journal-title":"Aust. J. Basic Appl. Sci."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"1","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_5","first-page":"441","article-title":"Review on lower extremity exoskeleton robot","volume":"7","author":"Li","year":"2015","journal-title":"Open Autom. Control Syst. J."},{"key":"ref_6","doi-asserted-by":"crossref","unstructured":"Pesenti, M., Antonietti, A., Gandolla, M., and Pedrocchi, A. (2021). Towards a functional performance validation standard for industrial low-back exoskeletons: State of the art review. Sensors, 21.","DOI":"10.3390\/s21030808"},{"key":"ref_7","doi-asserted-by":"crossref","unstructured":"Lee, T., Lee, D., Song, B., and Baek, Y. (2020). Design and control of a polycentric knee exoskeleton using an electro-hydraulic actuator. Sensors, 20.","DOI":"10.3390\/s20010211"},{"key":"ref_8","doi-asserted-by":"crossref","unstructured":"Chen, B., Lanotte, F., Grazi, L., Vitiello, N., and Crea, S. (2019). Classification of lifting techniques for application of a robotic hip exoskeleton. Sensors, 19.","DOI":"10.3390\/s19040963"},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"141","DOI":"10.4028\/www.scientific.net\/AMM.598.141","article-title":"Mechanical design of lower extremity exoskeleton assisting walking of load carrying human","volume":"598","author":"Kalyoncu","year":"2014","journal-title":"Appl. Mech. Mater."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"535","DOI":"10.1080\/01691864.2015.1135080","article-title":"Development of an underactuated exoskeleton for effective walking and load-carrying assist","volume":"30","author":"Yu","year":"2016","journal-title":"Adv. Robot."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"1026","DOI":"10.1109\/TMECH.2020.2970448","article-title":"Singular wire-driven series elastic actuation with force control for a waist assistive exoskeleton, H-WEXv2","volume":"25","author":"Hyun","year":"2020","journal-title":"IEEE ASME Trans. Mechatron."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"1794","DOI":"10.1109\/TMECH.2020.2995134","article-title":"Quasi-Direct drive actuation for a lightweight hip exoskeleton with high backdrivability and high bandwidth","volume":"25","author":"Yu","year":"2020","journal-title":"IEEE ASME Trans. Mechatron."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"2236","DOI":"10.1109\/TMECH.2019.2933983","article-title":"An unpowered flexible lower limb exoskeleton: Walking assisting and energy harvesting","volume":"24","author":"Xie","year":"2019","journal-title":"IEEE ASME Trans. Mechatron."},{"key":"ref_14","doi-asserted-by":"crossref","unstructured":"Neuhaus, P.D., Noorden, J.H., Craig, T.J., Torres, T., Kirschbaum, J., and Pratt, J.E. (2011, January 19). Design and evaluation of Mina: A robotic orthosis for paraplegics. Proceedings of the IEEE International Conference on Rehabilitation Robotics (ICORR), Zurich, Switzerland.","DOI":"10.1109\/ICORR.2011.5975468"},{"key":"ref_15","doi-asserted-by":"crossref","unstructured":"Strausser, K.A., Swift, T.A., Zoss, A.B., Kazerooni, H., and Bennett, B.C. (2011, January 31). Mobile exoskeleton for spinal cord injury: Development and testing. Proceedings of the Dynamic Systems and Control Conference (DSCC), Arlington, VA, USA.","DOI":"10.1115\/DSCC2011-6042"},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"84","DOI":"10.3109\/17483107.2012.688238","article-title":"Design of the wearable power-assist locomotor (WPAL) for paraplegic gait reconstruction","volume":"8","author":"Tanabe","year":"2013","journal-title":"Disabil. Rehabil. Assist. Technol."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"66338","DOI":"10.1109\/ACCESS.2020.2985910","article-title":"Design and preliminary validation of a lower limb exoskeleton with compact and modular actuation","volume":"8","author":"Li","year":"2020","journal-title":"IEEE Access"},{"key":"ref_18","doi-asserted-by":"crossref","unstructured":"Sanz-Merodio, D., Cestari, M., Arevalo, J.C., and Garcia, E. (2012, January 11). A lower-limb exoskeleton for gait assistance in quadriplegia. Proceedings of the IEEE International Conference on Robotics and Biomimetics (ROBIO), Guangzhou, China.","DOI":"10.1109\/ROBIO.2012.6490954"},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"128","DOI":"10.1109\/TMECH.2006.871087","article-title":"Biomechanical design of the Berkeley lower extremity exoskeleton (BLEEX)","volume":"11","author":"Zoss","year":"2006","journal-title":"IEEE ASME Trans. Mechatron."},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"274","DOI":"10.1109\/TMECH.2018.2790358","article-title":"Design and experimental verification of hip exoskeleton with balance capacities for walking assistance","volume":"23","author":"Zhang","year":"2018","journal-title":"IEEE ASME Trans. Mechatron."},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"319","DOI":"10.5772\/7250","article-title":"Balancing control of AIT leg exoskeleton using ZMP based FLC","volume":"6","author":"Aphiratsakun","year":"2009","journal-title":"Int. J. Adv. Robot. Syst."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"1520","DOI":"10.1109\/TMECH.2019.2922977","article-title":"Flexible gait enhancing mechatronics system for lower limb assistance (GEMS L-type)","volume":"24","author":"Lee","year":"2019","journal-title":"IEEE ASME Trans. Mechatron."},{"key":"ref_23","unstructured":"Kwa, H.K., Noorden, J.H., Missel, M., Craig, T., Pratt, J.E., and Neuhaus, P.D. (2009, January 12). Development of the IHMC mobility assist exoskeleton. Proceedings of the IEEE International Conference on Robotics and Automation (ICRA), Kobe, Japan."},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"1","DOI":"10.5772\/57238","article-title":"Mechanical design of a hybrid leg exoskeleton to augment load-carrying for walking","volume":"10","author":"Miao","year":"2013","journal-title":"Int. J. Adv. Robot. Syst."},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"785","DOI":"10.3182\/20060906-3-IT-2910.00131","article-title":"Control of a biomimetic \u201csoft-actuated\u201d lower body 10dof exoskeleton","volume":"39","author":"Costa","year":"2006","journal-title":"IFAC Proc. Vol."},{"key":"ref_26","doi-asserted-by":"crossref","unstructured":"Ganguly, A., Sanz-Merodio, D., Puyuelo, G., Go\u00f1i, A., Garces, E., and Garcia, E. (2018, January 1). Wearable pediatric gait exoskeleton: A feasibility study. Proceedings of the IEEE International Workshop on Intelligent Robots and Systems (IROS), Madrid, Spain.","DOI":"10.1109\/IROS.2018.8594211"},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"277","DOI":"10.1109\/TNSRE.2014.2365697","article-title":"Design and control of the MINDWALKER exoskeleton","volume":"23","author":"Wang","year":"2015","journal-title":"IEEE Trans. Neural Syst. Rehabil. Eng."},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"463","DOI":"10.1007\/s12555-013-0386-0","article-title":"Design of an exoskeleton with minimized energy consumption based on using elastic and dissipative elements","volume":"13","author":"Kim","year":"2015","journal-title":"Int. J. Control Autom. Syst."},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"32","DOI":"10.1016\/j.mechatronics.2017.06.009","article-title":"Design and locomotion control of a hydraulic lower extremity exoskeleton for mobility augmentation","volume":"46","author":"Kim","year":"2017","journal-title":"Mechatronics"},{"key":"ref_30","doi-asserted-by":"crossref","unstructured":"Cao, H., Ling, Z., Zhu, J., Wang, Y., and Wang, W. (2009, January 19). Design frame of a leg exoskeleton for load-carrying augmentation. Proceedings of the IEEE International Conference on Robotics and Biomimetics (ROBIO), Guilin, China.","DOI":"10.1109\/ROBIO.2009.5420684"},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"1","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_32","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_33","unstructured":"Low, K.H., Liu, X., and Yu, H. (2005, January 29). Development of NTU wearable exoskeleton system for assistive technologies. Proceedings of the IEEE International Conference on Mechatronics and Automation, Niagara Falls, ON, Canada."},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"487","DOI":"10.1142\/S0219843607001126","article-title":"A quasi-passive leg exoskeleton for load-carrying augmentation","volume":"4","author":"Walsh","year":"2007","journal-title":"Int. J. Hum. Robot."},{"key":"ref_35","doi-asserted-by":"crossref","unstructured":"S\u00e1nchez-Manchola, M., G\u00f3mez-Vargas, D., Casas-Bocanegra, D., M\u00fanera, M., and Cifuentes, C.A. (2018, January 22). Development of a robotic lower-limb exoskeleton for gait rehabilitation: AGoRA exoskeleton. Proceedings of the IEEE ANDESCON, Santiago de Cali, Colombia.","DOI":"10.1109\/ANDESCON.2018.8564692"},{"key":"ref_36","doi-asserted-by":"crossref","first-page":"441","DOI":"10.1007\/s11517-009-0437-0","article-title":"Improving backdrivability in geared rehabilitation robots","volume":"47","author":"Nef","year":"2009","journal-title":"Med. Biol. Eng. Comput."},{"key":"ref_37","doi-asserted-by":"crossref","unstructured":"Gardner, A.D., Potgieter, J., and Noble, F.K. (2017, January 21). A review of commercially available exoskeletons\u2019 capabilities. Proceedings of the International Conference on Mechatronics and Machine Vision in Practice (M2VIP), Auckland, New Zealand.","DOI":"10.1109\/M2VIP.2017.8211470"},{"key":"ref_38","doi-asserted-by":"crossref","first-page":"437","DOI":"10.3901\/CJME.2014.03.437","article-title":"Proceeding of human exoskeleton technology and discussions on future research","volume":"27","author":"Li","year":"2014","journal-title":"Chin. J. Mech. Eng."},{"key":"ref_39","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1186\/s12984-018-0360-4","article-title":"Development of VariLeg, an exoskeleton with variable stiffness actuation: First results and user evaluation from the CYBATHLON 2016","volume":"15","author":"Schrade","year":"2018","journal-title":"J. Neuroeng. Rehabil."},{"key":"ref_40","doi-asserted-by":"crossref","unstructured":"Zhang, Y., Guo, S., Cao, G., Zhang, S., and Liu, Y. (2016, January 7). A novel variable stiffness actuator-based exoskeleton device for home rehabilitation. Proceedings of the IEEE International Conference on Mechatronics and Automation, Harbin, China.","DOI":"10.1109\/ICMA.2016.7558678"},{"key":"ref_41","doi-asserted-by":"crossref","unstructured":"Mghames, S., Laghi, M., Santina, C.D., Garabini, M., Catalano, M., Grioli, G., and Bicchi, A. (2017, January 17). Design, control and validation of the variable stiffness exoskeleton FLExo. Proceedings of the IEEE International Conference on Rehabilitation Robotics (ICORR), London, UK.","DOI":"10.1109\/ICORR.2017.8009304"},{"key":"ref_42","unstructured":"Kang, O., Yun, J., Seo, S., Joe, H., Yi, H., and Lee, S. (2021). Design and implementation f spring mechanism with cam-follower for unpowered exoskeleton. IEEE ASME Trans. Mechatron., 1\u201311. under review."}],"container-title":["Sensors"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1424-8220\/21\/12\/4037\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T06:13:27Z","timestamp":1760163207000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1424-8220\/21\/12\/4037"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2021,6,11]]},"references-count":42,"journal-issue":{"issue":"12","published-online":{"date-parts":[[2021,6]]}},"alternative-id":["s21124037"],"URL":"https:\/\/doi.org\/10.3390\/s21124037","relation":{},"ISSN":["1424-8220"],"issn-type":[{"value":"1424-8220","type":"electronic"}],"subject":[],"published":{"date-parts":[[2021,6,11]]}}}