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Design and evaluation of a gait-adaptive passive ankle exoskeleton for metabolic cost reduction
Published online by Cambridge University Press: 07 April 2026
Abstract
Conventional active ankle exoskeletons are often bulky and heavily reliant on external power sources. This study presents a lightweight and flexible passive ankle exoskeleton (LFPA-EXO) aimed at reducing metabolic cost of walking. The LFPA-EXO features a gait-adaptive clutch (GA-clutch) and a super-elastic composite booster (SC-booster). By matching the walking gait, it stores gravitational potential energy and converts it into elastic energy through the booster, thereby reducing the metabolic cost of human locomotion. Mechanical and biomechanical evaluations demonstrate that the GA-clutch achieves less than 5% interference and over 85% assistance, indicating that the LFPA-EXO operates within the natural ankle joint range of motion without disrupting normal gait patterns. It delivers a peak assisting moment of 24.56 Nm during normal walking. Notably, it decreases the activation of the soleus muscle while moderately reducing the activation of the gastrocnemius muscle, with minimal impact on the tibialis anterior muscle. The LFPA-EXO achieves a 12.22% reduction in metabolic cost and an 11.17% decrease in average heart rate, underscoring its effectiveness in reducing metabolic cost during walking.
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- Copyright © The Author(s) 2026. Published by Cambridge University Press
References
Bettella, F., Tortora, S., Menegatti, E., Petrone, N. and Felice, A. D., “A scoping review on lower limb exoskeleton actuation’s description and characteristics,” Robotica 43, 1572–1589 (2025).CrossRefGoogle Scholar
Natali, C. D., Poliero, T., Sposito, M., Graf, E., Bauer, C., Pauli, C., Bottenberg, E., Eyto, A. D., O’Sullivan, L., Hidalgo, A. F., Scherly, D., Stadler, K. S., Caldwell, D. G. and Ortiz, J., “Design and evaluation of a soft assistive lower limb exoskeleton,” Robotica 37, 2014–2034 (2019).CrossRefGoogle Scholar
Sergi, F., Blank, A. and O’Malley, M., “Upper extremity exoskeleton for robot-aided rehabilitation,” Mech. Eng. 136, S6–S11 (2014).CrossRefGoogle Scholar
Viteckova, S., Kutilek, P., de Boisboissel, G., Krupicka, R., Galajdova, A., Kauler, J., Lhotska, L. and Szabo, Z., “Empowering lower limbs exoskeletons: State-of-the-art,” Robotica 36, 1743–1756 (2018).CrossRefGoogle Scholar
Kansal, S., Zubair, M., Suthar, B. and Mukherjee, S., “Tele-operation of an industrial robot by an arm exoskeleton for peg-in-hole operation using immersive environments,” Robotica 40, 234–249 (2022).CrossRefGoogle Scholar
Chen, B., Ni, X., Zi, B., Xu, Q. and Qian, J., “Design and implementation of upper-body exoskeleton for assistance of individuals with manual handling tasks,” J. Mech. Robot. 16, 071007 (2023).CrossRefGoogle Scholar
Guo, Y., Yang, X., Chen, Z., Yan, X. and Liu, F., “Design and analysis of an adaptive cable-driven knee unloading exoskeleton based on a rhombus linkage mechanism,” Robotica 43, 3461–3487 (2025).CrossRefGoogle Scholar
Han, Y. and Wang, X., “The biomechanical study of lower limb during human walking,” Sci. China Technol. Sci. 54, 983–991 (2011).CrossRefGoogle Scholar
Sawicki, G. S. and Ferris, D. P., “Powered ankle exoskeletons reveal the metabolic cost of plantar flexor mechanical work during walking with longer steps at constant step frequency,” J. Exp. Biol. 212, 21–31 (2009).CrossRefGoogle ScholarPubMed
Blazevich, A. and Fletcher, J., “More than energy cost: Multiple benefits of the long Achilles tendon in human walking and running,” Biol. Rev. 98(6) (2023).CrossRefGoogle Scholar
Zhang, J., Fiers, P., Witte, K. A., Jackson, R. W., Poggensee, K. L., Atkeson, C. G. and Collins, S. H., “Human-in-the-loop optimization of exoskeleton assistance during walking,” Science 356, 1280–1284 (2017).CrossRefGoogle ScholarPubMed
Tang, X., Wang, X., Ji, X., Zhou, Y., Yang, J., Wei, Y. and Zhang, W., “A wearable lower limb exoskeleton: Reducing the energy cost of human movement,” Micromachines-BASEL 13, 900 (2022).CrossRefGoogle ScholarPubMed
Sawicki, G. S., Beck, O. N., Kang, I. and Young, A. J., “The exoskeleton expansion: Improving walking and running economy,” J. NeuroEng. Rehab. 17, 25 (2020).CrossRefGoogle ScholarPubMed
Bougrinat, Y., Achiche, S. and Raison, M., “Design and development of a lightweight ankle exoskeleton for human walking augmentation,” Mechatronics 64, 102297 (2019).CrossRefGoogle Scholar
Zhou, L., Chen, W., Chen, W., Bai, S., Zhang, J. and Wang, J., “Design of a passive lower limb exoskeleton for walking assistance with gravity compensation,” Mech. Mach. Theory 150, 103840 (2020).CrossRefGoogle Scholar
Shao, Y., Zhang, W., Su, Y. and Ding, X., “Design and optimisation of load-adaptive actuator with variable stiffness for compact ankle exoskeleton,” Mech. Mach. Theory 161, 104323 (2021).CrossRefGoogle Scholar
Nasr, A., Ferguson, S. and McPhee, J., “Model-based design and optimization of passive shoulder exoskeletons,” J. Comput. Nonlinear Dyn. 17, 051004 (2022).CrossRefGoogle Scholar
Sutrisno, A. and Braun, D. J., “How to run 50% faster without external energy,” Sci. Adv. 6(13), eaay1950 (2020).CrossRefGoogle ScholarPubMed
Koller, J. R., Gates, D. H., Ferris, D. P. and Remy, C. D., ”“Body-in-the-Loop” Optimization of Assistive Robotic Devices: A Validation Study,” In: Robot. Sci. Syst. XII, Robotics: Science and Systems Foundation (2016).Google Scholar
Galle, S., Malcolm, P., Collins, S. H. and De Clercq, D., “Reducing the metabolic cost of walking with an ankle exoskeleton: Interaction between actuation timing and power,” J. Neuroeng. Rehab. 14, 35 (2017).CrossRefGoogle ScholarPubMed
Ding, Y., Galiana, I., Asbeck, A., Quinlivan, B., De Rossi, S. M. M. and Walsh, C., “Multi-joint Actuation Platform for Lower Extremity Soft Exosuits,” In: 2014 IEEE Int. Conf. Robot. Autom. ICRA (2014) pp. 1327–1334.Google Scholar
Mooney, L. M. and Herr, H. M., “Biomechanical walking mechanisms underlying the metabolic reduction caused by an autonomous exoskeleton,” J. Neuroeng. Rehab. 13, 4 (2016).CrossRefGoogle ScholarPubMed
Collins, S. H., Wiggin, M. B. and Sawicki, G. S., “Reducing the energy cost of human walking using an unpowered exoskeleton,” Nature 522, 212–215 (2015).CrossRefGoogle ScholarPubMed
Pardoel, S. and Doumit, M., “Development and testing of a passive ankle exoskeleton,” Biocybern. Biomed. Eng. 39, 902–913 (2019).CrossRefGoogle Scholar
Quinto, L., Pinheiro, P., Goncalves, S. B., Roupa, I., Simoes, P. and Silva, M. T. D., “Analysis of a passive ankle exoskeleton for reduction of metabolic costs during walking,” Def. Technol. 37, 62–68 (2023).CrossRefGoogle Scholar
Winter, D. A., ”Anthropometry,” In: Biomech. Mot. Control Hum. Mov. (John Wiley & Sons, Ltd, 2009) pp. 82–106.Google Scholar
Zhao, C., Ran, L., Liu, T. and Li, A., “Anthropometric Survey of Chinese Adult Population,” In: Proc. 20th Congr. Int. Ergon. Assoc. IEA 2018 (Springer International Publishing, Cham, 2018) pp. 434–441.Google Scholar
Fan, Y. and Wang, L., Biomechanics of Injury and Prevention (Springer Nature, 2022).CrossRefGoogle Scholar
Chen, S., Cai, L., Xie, F. and Jing, X., “Application of laser-induced graphene coating to retard interlaminar crack propagation in composites,” Compos. Part Appl. Sci. Manuf. 199, 109199 (2025).CrossRefGoogle Scholar
Williams, J., Graddage, N. and Rahatekar, S., “Effects of plasma modified carbon nanotube interlaminar coating on crack propagation in glass epoxy composites,” Compos. Part Appl. Sci. Manuf. 54, 173–181 (2013).CrossRefGoogle Scholar
Sharma, M., Gao, S., Mäder, E., Sharma, H., Wei, L. Y. and Bijwe, J., “Carbon fiber surfaces and composite interphases,” Compos. Sci. Technol. 102, 35–50 (2014).CrossRefGoogle Scholar
Forcellese, A., Simoncini, M., Vita, A., Giovannelli, A. and Leonardi, L., “Performance analysis of MWCNT/Epoxy composites produced by CRTM,” J. Mater. Process. Technol. 286, 116839 (2020).CrossRefGoogle Scholar
Cai, L., Chen, S., Xie, F. and Jing, X., “Laser-induced graphene for low-energy manufacturing of composites: Balancing performance enhancement and functional structural material integration,” Compos. Part B Eng. 307, 112975 (2025).CrossRefGoogle Scholar
Hong, H., Sarfraz, M. S., Jeong, M., Kim, T., Choi, J., Kong, K., Park, I. and Kim, S. S., “Prediction of ground reaction forces using the artificial neural network from capacitive self-sensing values of composite ankle springs for exo-robots,” Compos. Struct. 301, 116233 (2022).CrossRefGoogle Scholar
Kumar, M. S. and Vijayarangan, S., Analytical and experimental studies on fatigue life prediction of steel and composite multi-leaf spring for light passenger vehicles using life data analysis,” Mater. Sci. 13, 141–146 (2007).Google Scholar
Baumann, A. and Hausmann, J., “Compression fatigue testing setups for composites – A review,” Adv. Eng. Mater. 23, 2000646 (2021).CrossRefGoogle Scholar
Natarajan, V., Gangarao, H. V. S. and Shekar, V., “Fatigue response of fabric-reinforced polymeric composites,” J. Compos. Mater. 39, 1541–1559 (2005).CrossRefGoogle Scholar
Childers, W. L. and Takahashi, K. Z., “Increasing prosthetic foot energy return affects whole-body mechanics during walking on level ground and slopes,” Sci. Rep. 8, 5354 (2018).CrossRefGoogle ScholarPubMed
Zhang, X., Chen, Y. and Hu, J., “Recent advances in the development of aerospace materials,” Prog. Aerosp. Sci. 97, 22–34 (2018).CrossRefGoogle Scholar
Merletti, R., Rainoldi, A. and Farina, D., “Surface electromyography for noninvasive characterization of muscle,” Exerc. Sport Sci. Rev. 29, 20 (2001).CrossRefGoogle ScholarPubMed
Coifman, I., Kram, R. and Riemer, R., “Metabolic power response to added mass on the lower extremities during running,” Appl. Ergon. 114, 104109 (2024).CrossRefGoogle ScholarPubMed
Mooney, L. M., Rouse, E. J. and Herr, H. M., “Autonomous exoskeleton reduces metabolic cost of human walking,” J. Neuroeng. Rehab. 11, 151 (2014).CrossRefGoogle ScholarPubMed
Jing et al. supplementary material
Jing et al. supplementary material
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