{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,5,12]],"date-time":"2026-05-12T01:55:02Z","timestamp":1778550902506,"version":"3.51.4"},"reference-count":39,"publisher":"MDPI AG","issue":"20","license":[{"start":{"date-parts":[[2022,10,12]],"date-time":"2022-10-12T00:00:00Z","timestamp":1665532800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"National Key Research and Development Program of China","award":["2019YFB1312500"],"award-info":[{"award-number":["2019YFB1312500"]}]},{"name":"National Key Research and Development Program of China","award":["U1913216"],"award-info":[{"award-number":["U1913216"]}]},{"name":"National Key Research and Development Program of China","award":["E2020103001"],"award-info":[{"award-number":["E2020103001"]}]},{"name":"National Key Research and Development Program of China","award":["216Z1803G"],"award-info":[{"award-number":["216Z1803G"]}]},{"DOI":"10.13039\/501100001809","name":"National Natural Science Foundation of China","doi-asserted-by":"publisher","award":["2019YFB1312500"],"award-info":[{"award-number":["2019YFB1312500"]}],"id":[{"id":"10.13039\/501100001809","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100001809","name":"National Natural Science Foundation of China","doi-asserted-by":"publisher","award":["U1913216"],"award-info":[{"award-number":["U1913216"]}],"id":[{"id":"10.13039\/501100001809","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100001809","name":"National Natural Science Foundation of China","doi-asserted-by":"publisher","award":["E2020103001"],"award-info":[{"award-number":["E2020103001"]}],"id":[{"id":"10.13039\/501100001809","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100001809","name":"National Natural Science Foundation of China","doi-asserted-by":"publisher","award":["216Z1803G"],"award-info":[{"award-number":["216Z1803G"]}],"id":[{"id":"10.13039\/501100001809","id-type":"DOI","asserted-by":"publisher"}]},{"name":"Science and Technology (S&amp;T) Program of Hebei","award":["2019YFB1312500"],"award-info":[{"award-number":["2019YFB1312500"]}]},{"name":"Science and Technology (S&amp;T) Program of Hebei","award":["U1913216"],"award-info":[{"award-number":["U1913216"]}]},{"name":"Science and Technology (S&amp;T) Program of Hebei","award":["E2020103001"],"award-info":[{"award-number":["E2020103001"]}]},{"name":"Science and Technology (S&amp;T) Program of Hebei","award":["216Z1803G"],"award-info":[{"award-number":["216Z1803G"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>A stroke is a common disease that can easily lead to lower limb motor dysfunction in the elderly. Stroke survivors can effectively train muscle strength through leg flexion and extension training. However, available lower limb rehabilitation robots ignore the knee soft tissue protection of the elderly in training. This paper proposes a human\u2013robot cooperative lower limb active strength training based on a robust admittance control strategy. The stiffness change law of the admittance model is designed based on the biomechanics of knee joints, and it can guide the user to make force correctly and reduce the stress on the joint soft tissue. The controller will adjust the model stiffness in real-time according to the knee joint angle and then indirectly control the exertion force of users. This control strategy not only can avoid excessive compressive force on the joint soft tissue but also can enhance the stimulation of quadriceps femoris muscles. Moreover, a dual input robust control is proposed to improve the tracking performance under the disturbance caused by model uncertainty, interaction force and external noise. Experiments about the controller performance and the training feasibility were conducted with eight stroke survivors. Results show that the designed controller can effectively influence the interaction force; it can reduce the possibility of joint soft tissue injury. The robot also has a good tracking performance under disturbances. This control strategy also can enhance the stimulation of quadriceps femoris muscles, which is proved by measuring the muscle electrical signal and interaction force. Human\u2013robot cooperative strength training is a feasible method for training lower limb muscles with the knee soft tissue protection mechanism.<\/jats:p>","DOI":"10.3390\/s22207746","type":"journal-article","created":{"date-parts":[[2022,10,12]],"date-time":"2022-10-12T22:45:29Z","timestamp":1665614729000},"page":"7746","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":5,"title":["Human\u2013Robot Cooperative Strength Training Based on Robust Admittance Control Strategy"],"prefix":"10.3390","volume":"22","author":[{"given":"Musong","family":"Lin","sequence":"first","affiliation":[{"name":"Hebei Provincial Key Laboratory of Parallel Robot and Mechatronic System, Yanshan University, Qinhuangdao 066004, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Hongbo","family":"Wang","sequence":"additional","affiliation":[{"name":"Hebei Provincial Key Laboratory of Parallel Robot and Mechatronic System, Yanshan University, Qinhuangdao 066004, China"},{"name":"Academy for Engineering & Technology, Fudan University, Shanghai 200433, China"},{"name":"Shanghai Clinical Research Center for Aging and Medicine, Shanghai 200040, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Congliang","family":"Yang","sequence":"additional","affiliation":[{"name":"Hebei Provincial Key Laboratory of Parallel Robot and Mechatronic System, Yanshan University, Qinhuangdao 066004, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Wenjie","family":"Liu","sequence":"additional","affiliation":[{"name":"Hebei Provincial Key Laboratory of Parallel Robot and Mechatronic System, Yanshan University, Qinhuangdao 066004, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-8040-8396","authenticated-orcid":false,"given":"Jianye","family":"Niu","sequence":"additional","affiliation":[{"name":"Hebei Provincial Key Laboratory of Parallel Robot and Mechatronic System, Yanshan University, Qinhuangdao 066004, China"},{"name":"Key Laboratory of Advanced Forging & Stamping Technology and Science of Ministry of Education, Yanshan University, Qinhuangdao 066004, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Luige","family":"Vladareanu","sequence":"additional","affiliation":[{"name":"Robotics and Mechatronics Department, Institute of Solid Mechanics of Romanian Academy, 010141 Bucharest, Romania"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2022,10,12]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"1687814017737666","DOI":"10.1177\/1687814017737666","article-title":"Trajectory planning of a novel lower limb rehabilitation robot for stroke patient passive training","volume":"9","author":"Feng","year":"2017","journal-title":"Adv. Mech. Eng."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"57","DOI":"10.5772\/62445","article-title":"Teaching training method of a lower limb rehabilitation robot","volume":"13","author":"Feng","year":"2017","journal-title":"Int. J. Adv. Rob. Syst."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"439","DOI":"10.1016\/S1474-4422(19)30034-1","article-title":"Global, regional, and national burden of stroke, 1990\u20132016: A systematic analysis for the global burden of disease study 2016","volume":"18","author":"Johnson","year":"2019","journal-title":"Lancet Neurol."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"130","DOI":"10.1016\/j.jns.2015.04.033","article-title":"Gait training in subacute non-ambulatory stroke patients using a full weight-bearing gait-assistance robot: A prospective, randomized, open, blinded-endpoint trial","volume":"353","author":"Ochi","year":"2015","journal-title":"J. Neurol. Sci."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"3","DOI":"10.1186\/1743-0003-11-3","article-title":"A survey on robotic devices for upper limb rehabilitation","volume":"11","author":"Maciejasz","year":"2014","journal-title":"J. Neuroeng. Rehabil."},{"key":"ref_6","first-page":"1729881418776855","article-title":"Mechanical design and trajectory planning of a lower limb rehabilitation robot with a variable workspace","volume":"15","author":"Wang","year":"2018","journal-title":"Int. J. Adv. Rob. Syst."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"311","DOI":"10.1109\/TNSRE.2005.848352","article-title":"Robotic techniques for upper limb evaluation and rehabilitation of stroke patients","volume":"13","author":"Colombo","year":"2005","journal-title":"IEEE Trans. Neural Syst. Rehabil. Eng."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"175","DOI":"10.1109\/TOH.2013.73","article-title":"Mechanisms of motor recovery in chronic and subacute stroke patients following a robot-aided training","volume":"7","author":"Mazzoleni","year":"2014","journal-title":"IEEE Trans. Haptics"},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"201","DOI":"10.3233\/NRE-192778","article-title":"Efficacy of end-effector robot-assisted gait training in subacute stroke patients: Clinical and gait outcomes from a pilot bi-centre study","volume":"45","author":"Aprile","year":"2019","journal-title":"NeuroRehabilitation"},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"1198","DOI":"10.1080\/09593985.2020.1839986","article-title":"Strength training to improve walking after stroke: How physiotherapist, patient and workplace factors influence exercise prescription","volume":"38","author":"Tole","year":"2022","journal-title":"Physiother. Theory Pract."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"17298814211003461","DOI":"10.1177\/17298814211003461","article-title":"Design and evaluation of a surface electromyography-controlled lightweight upper arm exoskeleton rehabilitation robot","volume":"18","author":"Liu","year":"2021","journal-title":"Int. J. Adv. Rob. Syst."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"459","DOI":"10.1016\/j.cger.2019.07.005","article-title":"Resistance Training for Older Adults in Cardiac Rehabilitation","volume":"35","author":"Khadanga","year":"2019","journal-title":"Clin. Geriatr. Med."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"35","DOI":"10.1136\/jramc-2013-000008","article-title":"A comparison of two 3-week resistance training programmes commonly used in short-term military rehabilitation","volume":"159","author":"Kristensen","year":"2013","journal-title":"J. R. Army Med. Corps"},{"key":"ref_14","first-page":"11","article-title":"The X-10: A revolution in knee rehabilitation","volume":"3","author":"Halley","year":"2013","journal-title":"Reconstr. Rev."},{"key":"ref_15","first-page":"12","article-title":"Position controlled knee rehabilitation orthotic device for patients after total knee replacement arthroplasty","volume":"157","author":"Wannaphan","year":"2016","journal-title":"Iop Conf."},{"key":"ref_16","first-page":"9610745","article-title":"Knee-extension training with a single-joint hybrid assistive limb during the early postoperative period after total knee arthroplasty in a patient with osteoarthritis","volume":"9","author":"Yoshioka","year":"2016","journal-title":"Case Rep. Orthop."},{"key":"ref_17","first-page":"6912706","article-title":"The training effect of early intervention with a hybrid assistive limb after total knee arthroplasty","volume":"7","author":"Fukaya","year":"2017","journal-title":"Case Rep. Orthop."},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"611","DOI":"10.1515\/ijame-2016-0037","article-title":"Design and characterization of a novel knee articulation mechanism","volume":"21","author":"Olinski","year":"2016","journal-title":"Int. J. Appl. Mech. Eng."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"380","DOI":"10.1109\/TNSRE.2005.848628","article-title":"Patient-cooperative strategies for robot-aided treadmill training: First experimental results","volume":"13","author":"Riener","year":"2005","journal-title":"IEEE Trans. Neural Syst. Rehabil. Eng."},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"1005","DOI":"10.1109\/TSMC.2017.2771227","article-title":"Development of a minimal-intervention-based admittance control strategy for upper extremity rehabilitation exoskeleton","volume":"48","author":"Wu","year":"2018","journal-title":"IEEE Trans. Syst. Man Cybern.-Syst."},{"key":"ref_21","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","author":"Colgate","year":"2011","journal-title":"Int. J. Rob. Res."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"352","DOI":"10.1109\/TNSRE.2015.2511448","article-title":"LOPES II-design and evaluation of an admittance controlled gait training robot with shadow-leg approach","volume":"24","author":"Meuleman","year":"2016","journal-title":"IEEE Trans. Neural Syst. Rehabil. Eng."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"104177","DOI":"10.1016\/j.conengprac.2019.104177","article-title":"Optimal impedance via model predictive control for robot-aided rehabilitation","volume":"93","author":"Siqueira","year":"2019","journal-title":"Control Eng. Pract."},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"786","DOI":"10.1109\/TLA.2017.7910190","article-title":"Active rehabilitation exercises with a parallel structure ankle rehabilitation prototype","volume":"15","author":"Rosado","year":"2017","journal-title":"IEEE Lat. Am. Trans."},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"761","DOI":"10.1109\/THMS.2016.2562510","article-title":"iLeg\u2014A lower limb rehabilitation robot: A proof of concept","volume":"46","author":"Zhang","year":"2016","journal-title":"IEEE Trans. Hum.-Mach. Syst."},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"277","DOI":"10.1109\/TNSRE.2019.2949203","article-title":"Continuous description of human 3D motion intent through switching mechanism","volume":"28","author":"Huang","year":"2020","journal-title":"IEEE Trans. Neural Syst. Rehabil. Eng."},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"6497","DOI":"10.1109\/JSEN.2019.2910318","article-title":"Attention-controlled assistive wrist rehabilitation using a low-cost EEG sensor","volume":"19","author":"Li","year":"2019","journal-title":"IEEE Sens. J."},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"738","DOI":"10.1109\/TBME.2019.2920346","article-title":"FES Cycling in Stroke: Novel Closed-Loop Algorithm Accommodates Differences in Functional Impairments","volume":"67","author":"Rouse","year":"2020","journal-title":"IEEE Trans. Biomed. Eng."},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"447","DOI":"10.1016\/j.cger.2012.05.009","article-title":"Minimally invasive total hip and knee arthroplasty-implications for the elderly patient","volume":"28","author":"Reininga","year":"2012","journal-title":"Clin. Geriatr. Med."},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"51","DOI":"10.1053\/jpmn.2000.7782","article-title":"Knee osteoarthritis management therapies","volume":"1","author":"Leslie","year":"2000","journal-title":"Pain Manag. Nurs. Off. J. Am. Soc. Pain Manag. Nurses"},{"key":"ref_31","first-page":"63","article-title":"Joint load during the parallel squat in powerlifting and force analysis of in vivo bilateral quadriceps tendon rupture","volume":"8","author":"Nisell","year":"1986","journal-title":"Scand. J. Sports Sci."},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"293","DOI":"10.1016\/S0736-0266(03)00179-7","article-title":"In situ forces of the anterior and posterior cruciate ligaments in high knee flexion: An in vitro investigation","volume":"22","author":"Li","year":"2004","journal-title":"J. Orthop. Res."},{"key":"ref_33","doi-asserted-by":"crossref","first-page":"127","DOI":"10.1097\/00005768-200101000-00020","article-title":"Knee biomechanics of the dynamic squat exercise","volume":"33","author":"Escamilla","year":"2001","journal-title":"Med. Sci. Sports Exerc."},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"556","DOI":"10.1097\/00005768-199804000-00014","article-title":"Biomechanics of the knee during closed kinetic chain and open kinetic chain exercises","volume":"30","author":"Escamilla","year":"1998","journal-title":"Med. Sci. Sports Exerc."},{"key":"ref_35","doi-asserted-by":"crossref","unstructured":"Yan, H., Wang, H., Vladareanu, L., Lin, M., Vladareanu, V., and Li, Y. (2019). Detection of participation and training task difficulty applied to the multi-sensor systems of rehabilitation robots. Sensors, 19.","DOI":"10.3390\/s19214681"},{"key":"ref_36","doi-asserted-by":"crossref","unstructured":"Feng, Y., Wang, H., Vladareanu, L., Chen, Z., and Jin, D. (2019). New Motion Intention Acquisition Method of Lower Limb Rehabilitation Robot Based on Static Torque Sensors. Sensors, 19.","DOI":"10.3390\/s19153439"},{"key":"ref_37","doi-asserted-by":"crossref","first-page":"243","DOI":"10.1111\/j.1468-1331.1995.tb00078.x","article-title":"Muscle activity changes in spasmodic torticollis after botulinum toxin treatment","volume":"1","author":"Marin","year":"1995","journal-title":"Eur. J. Neurol."},{"key":"ref_38","doi-asserted-by":"crossref","first-page":"621","DOI":"10.1016\/j.jelekin.2005.10.003","article-title":"Further evaluation of an EMG technique for assessment of the deep cervical flexor muscles","volume":"16","author":"Falla","year":"2006","journal-title":"J. Electromyogr. Kinesiol."},{"key":"ref_39","doi-asserted-by":"crossref","first-page":"611","DOI":"10.1142\/S0219519410003599","article-title":"Comparison of the activities of the deep trunk muscles measured using intramuscular and surface electromyography","volume":"10","author":"Okubo","year":"2010","journal-title":"J. Mech. Med. Biol."}],"container-title":["Sensors"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1424-8220\/22\/20\/7746\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T00:52:49Z","timestamp":1760143969000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1424-8220\/22\/20\/7746"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2022,10,12]]},"references-count":39,"journal-issue":{"issue":"20","published-online":{"date-parts":[[2022,10]]}},"alternative-id":["s22207746"],"URL":"https:\/\/doi.org\/10.3390\/s22207746","relation":{},"ISSN":["1424-8220"],"issn-type":[{"value":"1424-8220","type":"electronic"}],"subject":[],"published":{"date-parts":[[2022,10,12]]}}}