Publications

Selected Publications

Slade, P., Atkeson, C. G., Donelan, J. M., Houdijk, H., Ingraham, K. A., Kim, M., Kong, K., Poggensee, K. L., Riener, R., Steinert, M., Zhang, J., Collins, S. H. (2024) On human-in-the-loop optimization of human-robot interaction. Nature, 633:779-788. Article | PDF

Diller, S., Majidi, C., Collins, S. H. (2016) A lightweight, low-power electroadhesive clutch and spring for exoskeleton actuation. In Proceedings International Conference on Robotics and Automation, pages 682-689.
Article | PDF | Videos | Explainer Video | Thread

Collins, S. H., Adamczyk, P. G., Kuo, A. D. (2009) Dynamic arm swinging in human walking. Proceedings of the Royal Society of London B., 276:3679-3688. Article | PDF | Supporting PDF | Videos

Collins, S. H., Ruina, A., Tedrake, R., Wisse, M. (2005) Efficient bipedal robots based on passive dynamic walkers. Science, 307:1082-1085. Article | PDF | Supporting PDF | Videos

Collins, S. H., Wisse, M., Ruina, A. (2001) A three-dimensional passive-dynamic walking robot with two legs and knees. The International Journal of Robotics Research, 20:607-615. Article | PDF | Videos

Additional Journal Articles

Raitor, M., Ruggles, S., Delp, S. L., Liu, C. K., Collins, S. H. (2024) Lower-limb exoskeletons appeal to both clinicians and older adults, especially for fall prevention and joint pain reduction. Transactions on Neural Systems and Rehabilitation Engineering, 32:1577-1585. Article | PDF | Supplementary Materials

Lakmazaheri, A., Song, S., Vuong, B. B., Biskner, B., Kado, D. M., Collins, S.H. (2024) Optimizing exoskeleton assistance to improve walking speed and energy economy for older adults. Journal of NeuroEngineering and Rehabilitation, 21:1. Article | PDF

Poggensee, K. L., Collins, S.H. (2024) Lower limb biomechanics of fully trained exoskeleton users reveal complex mechanisms behind the reductions in energy cost with human-in-the-loop optimization. Frontiers in Robotics and AI, 11:1283080. Article | PDF | Validation Video | Data

Werling, K., Bianco, N.A., Raitor, M., Stingel, J., Hicks, J.L., Collins, S.H., Delp, S.L., Liu, C.K. (2023) AddBiomechanics: Automating model scaling, inverse kinematics, and inverse dynamics from human motion data through sequential optimization. PLoS ONE, 18:e0295152.
Article | PDF | Code | addbiomechanics.org

Welker, C. G., Collins, S. H., Okamura, A. M. (2022) Human perception of wrist flexion and extension torque during upper and lower extremity movement. Transactions on Haptics, 15:741-752.
Article | PDF

Miller, D. E., Tan, G. R., Farina, E. M., Sheets-Singer, A. L., Collins, S. H. (2022) Characterizing the relationship between peak assistance torque and metabolic cost reduction during running with ankle exoskeletons. Journal of NeuroEngineering and Rehabilitation, 19:46.
Article | PDF | Thread

Franks, P. W., Bryan, G. M., Reyes, R., O'Donovan, M. P., Gregorczyk, K. N., Collins, S. H. (2022) The effects of incline level on optimized lower-limb exoskeleton assistance: a case series. Transactions on Neural Systems and Rehabilitation Engineering, 30:2494-2505.
Article | PDF

Abram, S. J., Poggensee, K. L., Sánchez, N., Simha, S. N., Finley, J. M., Collins, S. H., Donelan, J. M. (2022) General variability leads to specific adaptation toward optimal movement policies. Current Biology, 32:1-11.
Article | PDF | Thread

Butterfield, J. K., Collins, S. H. (2022) The energy cost of split-belt walking for a variety of belt speed combinations. Journal of Biomechanics, 132:110905.
Article | PDF | Thread | Split-Belt Machine

Song, S., Collins, S. H. (2021) Optimizing exoskeleton assistance for faster self-selected walking. Transactions on Neural Systems & Rehabilitation Engineering, 29:786-795.Article | PDF | Condition Video | Participants Video | Thread

Franks, P. W., Bryan, G. M., Martin, R. M., Reyes, R., Lakmazaheri, A. C., Collins, S. H. (2021) Comparing optimized exoskeleton assistance of the hip, knee, and ankle in single and multi-joint configurations. Wearable Technologies, 2:e16. Article | PDF

Chiu, V. L., Voloshina, A. S., Collins, S. H. (2021) The effects of ground-irregularity-cancelling prosthesis control on balance over uneven surfaces. Royal Society Open Science, 8:201235.Article | PDF | Conditions Video | Slow Motion | Treadmill Build Guide | Thread

Slade, P., Kochenderfer, M. J., Delp, S. L., Collins, S. H. (2021) Sensing leg movement enhances wearable monitoring of energy expenditure. Nature Communications, 12:1-11.
Article | PDF | Explainer Video

Yang, G. Z., Collins, S. H., Dario, P., Fischer, P., Goldberg, K., Laschi, C., McNutt, M. K (2021) Five years of Science Robotics. Science Robotics, 6:eabn2720.
Article | PDF

Caputo, J. M., Dvorak, E., Shipley, K., Miknevich, M. A., Adamczyk, P. G., Collins, S. H. (2021) Robotic emulation of candidate prosthetic foot designs may enable efficient, evidence-based, and individualized prescriptions. Journal of Prosthetics and Orthotics.
Article | PDF

Bryan, G. M., Franks, P. W., Song, S., Reyes, R., O'Donovan, M. P., Gregorczyk, K. N., Collins, S. H. (2021) Optimized hip-knee-ankle exoskeleton assistance reduces the metabolic cost of walking with worn loads. Journal of NeuroEngineering and Rehabilitation, 18:161.
Article | PDF | Thread

Chiu, V. L., Raitor, M., Collins, S. H. (2021) Design of a hip exoskeleton with actuation in frontal and sagittal planes. Transactions on Medical Robotics and Bionics, 3:773-782.
Article | PDF | Video | CAD

Bryan, G. M., Franks, P. W., Song, S., Voloshina, A. S., Reyes, R., O'Donovan, M. P., Gregorczyk, K. N., Collins, S. H. (2021) Optimized hip–knee–ankle exoskeleton assistance at a range of walking speeds. Journal of NeuroEngineering and Rehabilitation, 18:152.
Article | PDF | Supplementary PDF | Thread

Welker, C. G., Chiu, V. L., Voloshina, A. S., Collins, S. H. (2021) Shortcomings of human-in-the-loop optimization of an ankle-foot prosthesis emulator: a case series. Royal Society Open Science, 8:202020.
Article | PDF | Thread

Zhang, J., Collins, S. H. (2021) The iterative learning gain that optimizes real-time torque tracking for ankle exoskeletons in human walking under gait variations. Frontiers in Neurorobotics, 15:65.
Article | PDF

Welker, C. G., Chiu, V. L., Voloshina, A., Collins, S. H., Okamura, A. M. (2021) Teleoperation of an ankle-foot prosthesis with a wrist exoskeleton. Transactions on Biomedical Engineering, 68:1714-1725.
Article | PDF | Cover | Video | Thread

Tan*, G. R., Raitor*, M., Collins, S. H. (2020) Bump’em: an open-source, bump-emulation system for studying human balance and gait. In Proceedings International Conference on Robotics and Automation, pages 9093-9099.Article | PDF | System Video | Talk Video | Design Materials | Thread

Witte, K. A., Fiers, P., Sheets-Singer, A. L., Collins, S. H. (2020) Improving the energy economy of human running with powered and unpowered ankle exoskeleton assistance. Science Robotics, 5:eaay9108.Article | PDF | Supplementary PDF | Experiment Video | Explainer Video | Thread

Nguyen, T. M., Jackson, R. W., Aucie, Y., de Kam, D., Collins, S. H., Torres-Oviedo, G. (2020) Self-selected step length asymmetry is not explained by energy cost minimization in individuals with chronic stroke. Journal of NeuroEngineering and Rehabilitation, 17:119.
Article | PDF | Thread

Kim, M., Lyness, H., Chen, T., Collins, S. H. (2020) The effects of prosthesis inversion/eversion stiffness on balance-related variability during level walking: a pilot study. Journal of Biomechanical Engineering, 142:091011.
Article | PDF

Yang, G.-Z., Nelson, B. J., Murphy, R. R., Choset, H., Christensen, H., Collins, S. H., Dario, P., Goldberg, K., Ikuta, K., Jacobstein, N., Kragic, D., Taylor, R. H., McNutt, M. (2020) Combating COVID-19—The role of robotics in managing public health and infectious diseases. Science Robotics, 5:eabb5589.
Article | PDF

Simpson, C.S., Welker, C.G., Uhlrich, S.D., Sketch, S.M., Jackson, R.W., Delp, S.L., Collins, S.H., Selinger, J.C., Hawkes, E.W. (2019) Connecting the legs with a spring improves human running economy. Journal of Experimental Biology, 222:jeb202895.
Article | PDF | Supplementary Information | Cover

Jackson, R. W., Collins, S. H. (2019) Heuristic-based ankle exoskeleton control for co-adaptive assistance of human locomotion. Transactions on Neural Systems and Rehabilitation Engineering, 27:2059-2069.
Article | PDF | Video

Slade, P., Troutman, R., Kochenderfer, M. J., Collins, S. H., Delp, S. L. (2019) Rapid energy expenditure estimation for ankle assisted and inclined loaded walking. Journal of NeuroEngineering and Rehabilitation, 16:67.
Article | PDF

Diller, S. B., Collins, S. H., Majidi, C. (2018) The effects of electroadhesive clutch design parameters on performance characteristics. Journal of Intelligent Material Systems and Structures, 29:3804-3828.
Article | PDF | Videos

Jackson, R. W., Dembia, C. L., Delp, S. L., Collins, S. H. (2017) Muscle-tendon mechanics explain unexpected effects of exoskeleton assistance on metabolic rate during walking. Journal of Experimental Biology, 220:2082-2095.
Article | PDF | Supplementary PDF

Kim, M., Collins, S. H. (2017) Once-per-step control of ankle push-off work improves balance in a three-dimensional simulation of bipedal walking. Transaction on Robotics, 33:406-418.
Article | PDF | Animation

Zhang, J., Collins, S. H. (2017) The passive series stiffness that optimizes torque tracking for a lower-limb exoskeleton in human walking. Frontiers in Neurorobotics, 11:68.
Article | PDF

Kim, M., Collins, S. H. (2017) Step-to-step ankle inversion/eversion torque modulation can reduce effort associated with balance. Frontiers in Neurorobotics, 11:62.
Article | PDF

Steele, K. M., Jackson, R. W., Shuman, B., Collins, S. H. (2017) Muscle recruitment and coordination with an ankle exoskeleton. Journal of Biomechanics, 59:50-58.
Article | PDF

Galle, S., Malcolm, P., Collins, S. H., De Clercq, D. (2017) Reducing the metabolic cost of walking with an ankle exoskeleton: interaction between actuation timing and power. Journal of NeuroEngineering and Rehabilitation, 14:35.
Article | PDF | Supplementary PDF

Quesada, R. E., Caputo J. M., Collins, S.H. (2016) Increasing ankle push-off work with a powered prosthesis does not necessarily reduce metabolic rate for transtibial amputees. Journal of Biomechanics, 49:3452-3459.
Article | PDF | Supplementary PDF | Source Data

Jackson, R. W., Collins, S. H. (2015) An experimental comparison of the relative benefits of work and torque assistance in ankle exoskeletons. Journal of Applied Physiology, 119:541-557.
Article | PDF | Data | Video

Kim, M., Collins, S. H. (2015) Once-per-step control of ankle-foot prosthesis push-off work reduces effort associated with balance during human walking. Journal of NeuroEngineering and Rehabilitation, 12:43.
Article | PDF | Supplementary PDF | Video

Malcolm, P., Quesada, R. E., Caputo, J. M., Collins, S. H. (2015) The influence of push-off timing in a robotic ankle-foot prosthesis on the energetics and mechanics of walking. Journal of NeuroEngineering and Rehabilitation, 12:21.
Article | PDF | Supplementary PDF | Video

Caputo, J. M., Collins, S. H. (2014) Prosthetic ankle push-off work reduces metabolic rate but not collision work in non-amputee walking. Scientific Reports, 4:7213.
Article | PDF | Supplementary PDF | Video

Collins, S. H., Kuo, A. D. (2010) Recycling energy to restore impaired ankle function during human walking. Public Library of Science ONE, 5:e9307.
Article | PDF | Supporting PDF | High-speed Video | Images

Additional Book Chapters

Witte, K. A., and Collins, S. H. (2020) Design of lower-limb exoskeletons and emulator systems. In Wearable Robotics: Systems and Applications, with editors Ferguson, P. W., Rosen, J., Elsevier, Chapter 22, pages 251-274.
Chapter | PDF | BOM | CAD

Voloshina, A. S., and Collins, S. H. (2020) Lower limb active prosthetic systems—overview. In Wearable Robotics: Systems and Applications, with editors Ferguson, P. W., Rosen, J., Elsevier, Chapter 23, pages 469-486.
Chapter | PDF

Zhang, J., Cheah, C. C., and Collins, S. H. (2017) Torque control in legged locomotion. In Bio-Inspired Legged Locomotion: Models, Concepts, Control and Applications, with editors Sharbafi, M., Seyfarth, A., Butterworth-Heinemann, Chapter 5, pages: 347-395.
Book | Chapter PDF | Supplementary PDF

Additional Conference Proceedings

Bryan, G. M., Franks, P. W., Song, S., Collins, S. H. (2024) Pilot comparison of customized and generalized hip-knee-ankle exoskeleton torque profiles. In Proceedings International Conference on Robotics and Automation, pages 3256-3261.
Article | PDF

Krimsky, E., Collins, S. H. (2020) Optimal control of an energy-recycling actuator for mobile robotics applications. In Proceedings International Conference on Robotics and Automation, pages 3559-3565.
Article | PDF | Video | Talk Video

Franks*, P. W., Bianco*, N. A., Bryan, G. M., Hicks, J. L., Delp, S. L., Collins, S. H. (2020) Testing simulated assistance strategies on a hip-knee-ankle exoskeleton: a case study. In Proceedings IEEE International Conference on Biomedical Robotics and Biomechatronics, pages 700-707. *contributed equally.
Article | PDF | Talk Video | Video | Thread

Witte, K. A., Fatschel, A. M., Collins, S. H. (2017) Design of a lightweight, tethered, torque-controlled knee exoskeleton. In Proceedings IEEE International Conference on Rehabilitation Robotics, pages 1646-1653.
Article | PDF | Bandwidth Video

Caputo, J. M., Adamczyk, P. G., Collins, S. H. (2015) Informing ankle-foot prosthesis prescription through haptic emulation of candidate devices. In Proceedings IEEE International Conference on Robotics and Automation, pages 6445-6450.
Article | PDF | Video

Collins, S. H., Kim, M., Chen, T., Chen, T. (2015) An ankle-foot prosthesis emulator with control of plantarflexion and inversion-eversion torque. In Proceedings IEEE International Conference on Robotics and Automation, pages 1210-1216.
Article | PDF | Main Video | Walking Video | Two Toes | Talk Video

Witte, K. A., Zhang, J., Jackson, R. W., Collins, S.H. (2015) Design of two lightweight, high-bandwidth torque-controlled ankle exoskeletons. In Proceedings IEEE International Conference on Robotics and Automation, pages 1223-1228.
Article | PDF | Video

Zhang, J., Cheah, C., C., Collins, S.H. (2015) Experimental comparison of torque control methods on an ankle exoskeleton during human walking. In Proceedings IEEE International Conference on Robotics and Automation, pages 5584-5589.
Article | PDF

Collins, S. H., Caputo, J. M., Adamczyk, P. G. (2014) Emulating prosthetic feet during the prescription process to improve outcomes and justifications. In Proceedings IEEE Workshop on Advanced Robotics and its Social Impacts, pages 127-128.
Article | PDF

Collins, S. H. (2013) What do walking humans want from mechatronics? (Invited presentation). In Proceedings International Conference on Mechatronics, pages 24-27.
Article | PDF

Collins, S. H., Jackson, R. W. (2013) Inducing self-selected human engagement in robotic locomotion training. In Proceedings International Conference on Rehabilitation Robotics, 6 pages.
Article | PDF

Kim, M., Collins, S. H. (2013) Stabilization of a three-dimensional limit cycle walking model through step-to-step ankle control. In Proceedings International Conference on Rehabilitation Robotics, 6 pages.
Article | PDF

Caputo, J. M., Collins, S. H. (2013) An experimental robotic testbed for accelerated development of ankle prostheses. In Proceedings International Conference on Robotics and Automation, pages 2630-2635.
Article | PDF

Zhang, J., Cheah, C. C., Collins, S. H. (2013) Stable human-robot interaction control for upper-limb rehabilitation robotics. In Proceedings International Conference on Robotics and Automation, pages 2201-2206.
Article | PDF

Song, S., LaMontagna, C., Collins, S. H., Geyer, H. (2013) The effect of foot compliance encoded in the windlass mechanism on the energetics of human walking. In Proceedings International Conference of the Engineering in Medicine and Biology Society, pages 3179-3182.
Article | PDF

Wiggin, M. B., Sawicki, G. S., Collins, S. H. (2011) An exoskeleton using controlled energy storage and release to aid ankle propulsion. In Proceedings International Conference on Rehabilitation Robotics, 6 pages.
Article | PDF

Collins, S. H., Ruina, A. (2005) A bipedal walking robot with efficient and human-like gait. In Proceedings International Conference on Robotics and Automation, pages 1983-1988.
Article | PDF

Pratt, J. E., Krupp, B. T., Morse, C. J., Collins, S. H. (2004) The RoboKnee: an exoskeleton for enhancing strength and endurance during walking. In Proceedings International Conference on Robotics and Automation, pages 2430-2435.
Article | PDF | Video

Preprints

Wu, M. R., Adamczyk, P. G., Collins, S. H. (2021) Weighted shoes in the wild: Initial insights into the relationship between the effort of walking and the amount of walking performed. On bioRxiv. Article

Dissertations and Theses

Guan Rong Tan (2023) Design of exoskeletons and robotic tools for improving mobility. PhD Dissertation, Dept. of Mechanical Engineering, Stanford University, 95 pages. PDF

Erez Krimsky (2023) Elastic energy-recycling actuators for efficient robotics. PhD Dissertation, Dept. of Mechanical Engineering, Stanford University, 122 pages. PDF

Julia K. Butterfield (2022) The energetics of split-belt walking. PhD Dissertation, Dept. of Mechanical Engineering, Stanford University, 168 pages. PDF

Thu Nguyen (2022) Towards assisting walking in individuals with chronic stroke using exoskeletons. PhD Dissertation, Dept. of Mechanical Engineering, Stanford University, 71 pages. PDF

Patrick Slade (2021) Wearable systems for monitoring physical activity and optimizing exoskeletons. PhD Dissertation, Dept. of Mechanical Engineering, Stanford University, 79 pages. PDF

Cara G. Welker (2021) Sensorimotor control of lower-limb assistive devices. PhD Dissertation, Dept. of Bioengineering, Stanford University, 139 pages. PDF

Gwendolyn M. Bryan (2021) Development of effective hip-knee-ankle exoskeleton assistance for different walking conditions. PhD Dissertation, Dept. of Mechanical Engineering, Stanford University, 138 pages. PDF

Patrick W. Franks (2021) Designing multi-joint exoskeleton assistance. PhD Dissertation, Dept. of Mechanical Engineering, Stanford University, 152 pages. PDF

Katherine L. Poggensee (2021) Understanding the human contribution to the human-exoskeleton system. PhD Dissertation, Department of Mechanical Engineering, Stanford University, 152 pages. PDF

Vincent L. Chiu (2021) Design and testing of an ankle-foot prosthesis and a hip exoskeleton to improve balance-related outcomes and prevent falls. PhD Dissertation, Department of Mechanical Engineering, Stanford University, 128 pages. PDF

Stuart B. Diller (2018) Design, characterization, and implementation of lightwieght and energy-efficient electroadhesive clutches for robotics. PhD Dissertation, Department of Mechanical Engineering, Carnegie Mellon University, 125 pages. PDF

Kirby Ann Witte (2018) Design, characterization, and implementation of lower-limb exoskeletons for performance augmentation during walking and running. PhD Dissertation, Department of Mechanical Engineering, Carnegie Mellon University, 166 pages. PDF

Rachel W. Jackson (2017) Developing ankle exoskeleton assistance strategies by leveraging the mechanisms involved in human locomotion. PhD Dissertation, Department of Mechanical Engineering, Carnegie Mellon University, 152 pages. PDF

Juanjuan Zhang (2016) Towards systematic controller design in rehabilitation robots. PhD Dissertation, Department of Mechanical Engineering, Carnegie Mellon University, 271 pages. PDF

Blair J. Emanuel (2016) A Disturbance emulation device for stability and recovery testing. Master's thesis, Department of Mechanical Engineering, Carnegie Mellon University, 6 pages. PDF

James Gabriel (2016) Design and Deployment of a knee prosthesis emulator system. Master's thesis, Department of Mechanical Engineering, Carnegie Mellon University, 6 pages. PDF

Myunghee Kim (2015) Ankle controller design for robotic ankle-foot prostheses to reduce balance-related effort during walking using a dynamic walking approach. PhD Dissertation, Department of Mechanical Engineering, Carnegie Mellon University, 205 pages. PDF

Joshua M. Caputo (2015) Informing ankle-foot prosthesis design and prescription through systematic experimentation with a tethered robotic prosthesis. PhD Dissertation, Department of Mechanical Engineering, Carnegie Mellon University, 154 pages. PDF

van Zijl, L. H. F. (2009) Changing Speed in a Simple Walker with Dynamic One-Step Transitions. Master's thesis, Department of BioMechanical Engineering, Delft University of Technology, 20 pages. PDF

Additional prior publications by Prof. Collins are available at his archive website. You can learn more about our spinoff companies on our commercial translation page. Please contact us if you have difficulty accessing any article or related materials: stevecollins@stanford.edu.