{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,4,21]],"date-time":"2026-04-21T07:18:25Z","timestamp":1776755905291,"version":"3.51.2"},"reference-count":40,"publisher":"MDPI AG","issue":"1","license":[{"start":{"date-parts":[[2023,1,18]],"date-time":"2023-01-18T00:00:00Z","timestamp":1674000000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Chulalongkorn University","award":["CU_FRB65_ind (14)_162_21_28"],"award-info":[{"award-number":["CU_FRB65_ind (14)_162_21_28"]}]},{"name":"National Research Council of Thailand","award":["CU_FRB65_ind (14)_162_21_28"],"award-info":[{"award-number":["CU_FRB65_ind (14)_162_21_28"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Robotics"],"abstract":"<jats:p>This paper presents a novel wheelchair\u2013exoskeleton hybrid robot that can transform between sitting and walking modes. The lower-limb exoskeleton uses planetary-geared motors to support the hip and knee joints. Meanwhile, the ankle joints are passive. The left and right wheel modules can be retracted to the lower legs of the exoskeleton to prepare for walking or stepping over obstacles. The chair legs are designed to form a stable sitting posture to avoid falling while traveling on smooth surfaces with low energy consumption. Skateboard hub motors are used as the front driving wheels along with the rear caster wheels. The turning radius trajectory as the result of differential driving was observed in several scenarios. For assisting sit-to-stand motion, the desired joint velocities are commanded by the user while the damping of the motors is set. For stand-to-sit motion, the equilibrium of each joint is set to correspond to the standing posture, while stiffness is adjusted on the basis of assistive levels. The joint torques supported by the exoskeleton were recorded during motion, and leg muscle activities were studied via surface electromyography for further improvement.<\/jats:p>","DOI":"10.3390\/robotics12010016","type":"journal-article","created":{"date-parts":[[2023,1,19]],"date-time":"2023-01-19T02:04:35Z","timestamp":1674093875000},"page":"16","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":42,"title":["Transformable Wheelchair\u2013Exoskeleton Hybrid Robot for Assisting Human Locomotion"],"prefix":"10.3390","volume":"12","author":[{"ORCID":"https:\/\/orcid.org\/0000-0001-5002-7568","authenticated-orcid":false,"given":"Ronnapee","family":"Chaichaowarat","sequence":"first","affiliation":[{"name":"International School of Engineering, Chulalongkorn University, 254 Phayathai Road, Pathumwan, Bangkok 10330, Thailand"}]},{"given":"Sarunpat","family":"Prakthong","sequence":"additional","affiliation":[{"name":"International School of Engineering, Chulalongkorn University, 254 Phayathai Road, Pathumwan, Bangkok 10330, Thailand"}]},{"given":"Siri","family":"Thitipankul","sequence":"additional","affiliation":[{"name":"International School of Engineering, Chulalongkorn University, 254 Phayathai Road, Pathumwan, Bangkok 10330, Thailand"}]}],"member":"1968","published-online":{"date-parts":[[2023,1,18]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"12","DOI":"10.5772\/10669","article-title":"Design history and advantages of a new lever-propelled wheelchair prototype","volume":"8","author":"Sarraj","year":"2011","journal-title":"Int. J. Adv. Robot Syst."},{"key":"ref_2","doi-asserted-by":"crossref","unstructured":"Sasaki, K., Eguchi, Y., and Suzuki, K. (October, January 28). Step-climbing wheelchair with lever propelled rotary legs. Proceedings of the 2015 IEEE\/RSJ International Conference on Intelligent Robots and Systems, Hamburg, Germany.","DOI":"10.1109\/IROS.2015.7354285"},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"323","DOI":"10.1109\/TNSRE.2003.816875","article-title":"Modeling of a stair-climbing wheelchair mechanism with high single step capability","volume":"11","author":"Lawn","year":"2003","journal-title":"IEEE Trans. Neural Syst. Rehabil. Eng."},{"key":"ref_4","doi-asserted-by":"crossref","unstructured":"Chatterjee, P., Lahiri, N., Bhattacharjee, A., and Chakraborty, A. (2021, January 24\u201326). Automated hybrid stair climber for physically challenged people. Proceedings of the International Conference on Electronics, Materials Engineering & Nano-Technology, Kolkata, India.","DOI":"10.1109\/IEMENTech53263.2021.9614713"},{"key":"ref_5","unstructured":"Suryanto, M.F.I., Badriawan, N.A., Ningrum, E.S., Binugroho, E.H., and Satria, N.F. (2018, January 29\u201330). Balance control on the development of electric wheelchair prototype with standing and stair climbing ability with tracked-wheel mechanism. Proceedings of the 2018 International Electronics Symposium on Engineering Technology and Applications, Bali, Indonesia."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"164","DOI":"10.1093\/rheumatology\/20.3.164","article-title":"An investigation into the problems of easy chairs used by the arthritic and the elderly","volume":"20","author":"Munton","year":"1981","journal-title":"Rheum. Rehabil."},{"key":"ref_7","first-page":"503","article-title":"Kinesiological analysis of standing-up movement","volume":"804","author":"Mano","year":"1988","journal-title":"Excerpta Med. Int Congr. Ser."},{"key":"ref_8","unstructured":"(2022, December 11). Levo: Products. Available online: https:\/\/www.levo.ch\/products."},{"key":"ref_9","unstructured":"(2022, December 11). Superior ME. Available online: http:\/\/Superiorstanding.mamutweb.com\/subdet1.htm."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"1608","DOI":"10.1109\/TMECH.2018.2799865","article-title":"Standing mobility device with passive lower limb exoskeleton for upright locomotion","volume":"23","author":"Eguchi","year":"2018","journal-title":"IEEE ASME Trans. Mechatron."},{"key":"ref_11","doi-asserted-by":"crossref","unstructured":"Hayashi, T., Kawamoto, H., and Sankai, Y. (2005, January 2\u20136). Control method of robot suit HAL working as operator\u2019s muscle using biological and dynamical information. Proceedings of the 2005 IEEE\/RSJ International Conference Intelligent Robots and Systems, Edmonton, AB, Canada.","DOI":"10.1109\/IROS.2005.1545505"},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"56","DOI":"10.1109\/MPUL.2012.2196836","article-title":"The next generation of exoskeletons: Lighter, cheaper devices are in the works","volume":"3","author":"Mertz","year":"2012","journal-title":"IEEE Pulse"},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"96","DOI":"10.1179\/2045772312Y.0000000003","article-title":"Safety and tolerance of the ReWalk\u2122 exoskeleton suit for ambulation by people with complete spinal cord injury: A pilot study","volume":"35","author":"Zeilig","year":"2012","journal-title":"J. Spinal Cord Med."},{"key":"ref_14","doi-asserted-by":"crossref","unstructured":"Barbareschi, G., Richards, R., Thornton, M., Carlson, T., and Holloway, C. (2015, January 25\u201329). Statically vs dynamically balanced gait: Analysis of a robotic exoskeleton compared with a human. Proceedings of the 2015 IEEE\/EMBS Annual International Conference, Milan, Italy.","DOI":"10.1109\/EMBC.2015.7319937"},{"key":"ref_15","doi-asserted-by":"crossref","unstructured":"Duddy, D., Doherty, R., Connolly, J., McNally, S., Loughrey, J., and Faulkner, M. (2021). The effects of powered exoskeleton gait training on cardiovascular function and gait performance: A systematic review. Sensors, 21.","DOI":"10.3390\/s21093207"},{"key":"ref_16","doi-asserted-by":"crossref","unstructured":"Borisoff, J.F., Mattie, J., and Rafer, V. (2013, January 24\u201326). Concept proposal for a detachable exoskeleton-wheelchair to improve mobility and health. Proceedings of the 2013 IEEE International Conference on Rehabilitation Robotics, Seattle, WA, USA.","DOI":"10.1109\/ICORR.2013.6650396"},{"key":"ref_17","unstructured":"Shankar, T., and Dwivedy, S.K. (2015, January 5\u20137). A hybrid assistive wheelchair-exoskeleton. Proceedings of the 2015 International Convention on Rehabilitation Engineering and Assistive Technology, Singapore."},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"11","DOI":"10.5194\/ms-10-11-2019","article-title":"Mechanism design and analysis of a proposed wheelchair-exoskeleton hybrid robot for assisting human movement","volume":"10","author":"Song","year":"2019","journal-title":"Mech. Sci."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"2945","DOI":"10.1109\/LRA.2022.3145050","article-title":"Macro-mini linear actuator using electrorheological-fluid brake for impedance modulation in physical human\u2013robot interaction","volume":"7","author":"Chaichaowarat","year":"2022","journal-title":"IEEE Robot Autom. Lett."},{"key":"ref_20","doi-asserted-by":"crossref","unstructured":"Chaichaowarat, R., Nishimura, S., and Krebs, H.I. (June, January 30). Design and modeling of a variable-stiffness spring mechanism for impedance modulation in physical human\u2013robot interaction. Proceedings of the 2021 IEEE International Conference on Robotics and Automation, Xi\u2019an, China.","DOI":"10.1109\/ICRA48506.2021.9560966"},{"key":"ref_21","first-page":"609","article-title":"Biomechanical analysis of the sit-to-stand motion in elderly persons","volume":"73","author":"Millington","year":"1992","journal-title":"Arch. Phys. Med. Rehabil."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"871","DOI":"10.1007\/s40520-015-0486-1","article-title":"Sit to stand in elderly fallers vs non-fallers: New insights from force platform and electromyography data","volume":"28","author":"Chorin","year":"2016","journal-title":"Aging Clin. Exp. Res."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"1497","DOI":"10.1016\/j.procs.2016.08.196","article-title":"Estimation of joint torque and power consumption during sit-to-stand motion of human-being using a genetic algorithm","volume":"96","author":"Pal","year":"2016","journal-title":"Procodia Comp. Sci."},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"145","DOI":"10.37190\/ABB-01991-2021-05","article-title":"A kinematic model of a humanoid lower limb exoskeleton with pneumatic actuators","volume":"24","author":"Glowinski","year":"2022","journal-title":"Acta Bioeng. Biomech."},{"key":"ref_25","unstructured":"Huo, W., Mohammed, S., Amirat, Y., and Kong, K. (2016, January 9\u201314). Active impedance control of a lower limb exoskeleton to assist sit-to-stand movement. Proceedings of the 2016 IEEE\/RSJ International Conference on Intelligent Robots and Systems, Daejeon, Republic of Korea."},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"1615","DOI":"10.1163\/016918610X512622","article-title":"Sit-to-stand and stand-to-sit transfer support for complete paraplegic patients with robot suit HAL","volume":"24","author":"Tsukahara","year":"2010","journal-title":"Adv. Robot"},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"1122","DOI":"10.1115\/1.2216732","article-title":"Design of a passive gravity-balanced assistive device for sit-to-stand tasks","volume":"128","author":"Fattah","year":"2006","journal-title":"J. Mech. Des."},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"1650014","DOI":"10.1142\/S0219843616500146","article-title":"Analyzing and reducing energy usage in a humanoid robot during standing up and sitting down tasks","volume":"13","author":"Elibol","year":"2016","journal-title":"Int. J. Hum. Robot"},{"key":"ref_29","doi-asserted-by":"crossref","unstructured":"Kim, J., Yang, J., Yang, S.T., Oh, Y., and Lee, G. (2020). Energy-efficient hip joint offsets in humanoid robot via Taguchi method and bioinspired analysis. Appl. Sci., 10.","DOI":"10.3390\/app10207287"},{"key":"ref_30","doi-asserted-by":"crossref","unstructured":"Almeida, L., Ji, J., Steinbauer, G., and Luke, S. (2015). Power usage reduction of humanoid standing process using Q-learning. RoboCup 2015: Robot World Cup XIX, Lecture Notes in Computer Science, Springer. 9513.","DOI":"10.1007\/978-3-319-29339-4"},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"1223","DOI":"10.1016\/0021-9290(95)00178-6","article-title":"Adjustments to Zatsiorsky\u2013Seluyanov\u2019s segment inertia parameters","volume":"29","year":"1996","journal-title":"J. Biomech."},{"key":"ref_32","doi-asserted-by":"crossref","unstructured":"Chaichaowarat, R., Granados, D.F.P., Kinugawa, J., and Kosuge, K. (2017, January 24\u201328). Passive knee exoskeleton using torsion spring for cycling assistance. Proceedings of the 2017 IEEE\/RSJ International Conference on Intelligent Robots and Systems, Vancouver, BC, Canada.","DOI":"10.1109\/IROS.2017.8206146"},{"key":"ref_33","first-page":"81","article-title":"Full-slip kinematics based estimation of vehicle yaw rate from differential wheel speeds","volume":"17","author":"Chaichaowarat","year":"2016","journal-title":"KSAE Int. J. Automot. Tech."},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"89","DOI":"10.4186\/ej.2016.20.2.89","article-title":"Kinematics-based analytical solution for wheel slip angle estimation of a RWD vehicle with drift","volume":"20","author":"Chaichaowarat","year":"2016","journal-title":"Eng. J."},{"key":"ref_35","doi-asserted-by":"crossref","unstructured":"Chaichaowarat, R., and Wannasuphoprasit, W. (2019, January 16\u201318). Wheel slip angle estimation of a planar mobile platform. Proceedings of the 1st International Symposium on Instrumentation, Control, Artificial Intelligence, and Robotics, Bangkok, Thailand.","DOI":"10.1109\/ICA-SYMP.2019.8646198"},{"key":"ref_36","doi-asserted-by":"crossref","first-page":"471","DOI":"10.1016\/j.eng.2018.07.011","article-title":"Unpowered knee exoskeleton reduces quadriceps activity during cycling","volume":"4","author":"Chaichaowarat","year":"2018","journal-title":"Engineering"},{"key":"ref_37","doi-asserted-by":"crossref","unstructured":"Chaichaowarat, R., Kinugawa, J., and Kosuge, K. (2018, January 18\u201321). Cycling enhance knee exoskeleton using planar spiral spring. Proceedings of the 2018 IEEE\/EMBS Annual International Conference, Honolulu, HI, USA.","DOI":"10.1109\/EMBC.2018.8512862"},{"key":"ref_38","doi-asserted-by":"crossref","unstructured":"Chaichaowarat, R., Kinugawa, J., Seino, A., and Kosuge, K. (2020, January 6\u20139). A spring-embedded planetary-geared parallel elastic actuator. Proceedings of the 2020 IEEE\/ASME International Conference on Advanced Intelligent Mechatronics, Boston, MA, USA.","DOI":"10.1109\/AIM43001.2020.9158998"},{"key":"ref_39","doi-asserted-by":"crossref","unstructured":"Javadi, A., and Chaichaowarat, R. (2022). Position and stiffness control of an antagonistic variable stiffness actuator with input delay using super-twisting sliding mode control. Nonlinear Dyn., 1\u201323.","DOI":"10.21203\/rs.3.rs-1993578\/v1"},{"key":"ref_40","doi-asserted-by":"crossref","unstructured":"Chaichaowarat, R., Macha, V., and Wannasuphoprasit, W. (2020, January 16\u201319). Passive knee exoskeleton using brake torque to assist stair ascent. Proceedings of the 2020 IEEE Region 10 Conference, Osaka, Japan.","DOI":"10.1109\/TENCON50793.2020.9293832"}],"container-title":["Robotics"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2218-6581\/12\/1\/16\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,10]],"date-time":"2025-10-10T18:09:30Z","timestamp":1760119770000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2218-6581\/12\/1\/16"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2023,1,18]]},"references-count":40,"journal-issue":{"issue":"1","published-online":{"date-parts":[[2023,2]]}},"alternative-id":["robotics12010016"],"URL":"https:\/\/doi.org\/10.3390\/robotics12010016","relation":{},"ISSN":["2218-6581"],"issn-type":[{"value":"2218-6581","type":"electronic"}],"subject":[],"published":{"date-parts":[[2023,1,18]]}}}