Selected Publications

Zhang, J., Fiers, P., Witte, K. A., Jackson, R. W., Poggensee, K. L., Atkeson, C. G., Collins, S. H. (2017)
Human-in-the-loop optimization of exoskeleton assistance during walking. Science, 356:1280-1284.
Article | Author PDF | Supplementary PDF | Optimization Code | Study Data | Videos | Photos

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, in press.
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. Transactions on Robotics, 33:406-418.
PDF | Animation

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.
PDF | Supplementary PDF | Source Data

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.
PDF | Video | Demo Video | Discussion Video

Collins, S. H., Wiggin, M. B., Sawicki, G. S. (2015) Reducing the energy cost of human walking using an unpowered exoskeleton. Nature, 522:212-215.
Article | PDF | Supplementary PDF | Clutch Design | CAD | Results Table | Source Data | Videos | Photos

Caputo, J. M., Collins, S. H. (2014) A universal ankle-foot prosthesis emulator for human locomotion experiments. Journal of Biomechanical Engineering, 136:035002.
PDF | History | Videos | Images | 3D PDF | Bill of Materials | CAD Files | Matlab Code

Additional Journal Articles

Kim, M., Lyness, H., Chen, T., Collins, S. H. Prosthesis inversion-eversion stiffness reduces balance-related variability during level walking. Transactions on Neural Systems & Rehabilitation Engineering, in review.

Kim, M., Collins, S. H. Step-to-step ankle inversion/eversion torque modulation can reduce effort associated with balance. Frontiers in Neurorobotics, in review.

Witte, K. A., Zhang, J., Jackson, R. W., Collins, S. H. Design and characterization of two lightweight high-bandwidth torque-controlled ankle exoskeletons. Journal of BioMechanical Engineering, in review.

Kim, M., Chen, T., Chen, T., Collins, S. H. An ankle-foot prosthesis emulator with control of plantarflexion and inversion-eversion torque. Transactions on Robotics, in review.

Steele, K. M., Jackson, R. W., Shuman, B., Collins, S. H. Muscle recruitment and coordination with an ankle exoskeleton. Journal of Biomechanics, in press. Article | PDF

Zhang, J., Cheah, C. C., and Collins, S. H. (2017) Torque control in legged locomotion. In Bio-Inspired Legged Locomotion: Concepts, Control and Implementation, with editors Sharbafi, M., Seyfarth, A., Elsevier, in press. PDF | Supplementary 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

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. PDF | Video | Data

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.
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. 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. Nature Scientific Reports, 4:7213. PDF | Supplementary PDF | Video

Additional Conference Proceedings

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, in press.
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. 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*. PDF | Talk Video | Main Video | Toe Demo Video | Additional Video
* Best Medical Robotics Paper Award, ICRA 2015.

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. 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. 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. PDF

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

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

Dissertations and Theses

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

Conference Abstracts

Collins, S. H. (2017) Automatic customization of exoskeleton control during walking. Dynamic Walking, Mariehamn, Åland, Finland, June 4-9, 2017. PDF

Poggensee, K. L., Sreenath, K., Collins, S. H. (2017) Understanding the mechanisms behind human-in-the-loop optimization strategies. Dynamic Walking, Mariehamn, Åland, Finland, June 4-9, 2017. PDF

Witte, K. A., Collins, S. H. (2017) An experimental comparison of human-in-the-loop optimized ankle exoskeleton control strategies. Dynamic Walking, Mariehamn, Åland, Finland, June 4-9, 2017. PDF

Chiu, V. L., Voloshina, A. S., Collins, S. H. (2017) Implementing human-in-the-loop optimization on prosthesis emulators. Dynamic Walking, Mariehamn, Åland, Finland, June 4-9, 2017. PDF

Jackson, R. W., Collins, S. H. (2017) Heuristic-based online adaptation of ankle exoskeleton assistance using plantarflexor electromyography. Dynamic Walking, Mariehamn, Åland, Finland, June 4-9, 2017. PDF

Franks, P. W., Bryan, G., Klein, S. C., Collins, S. H. (2017) Design of a bilateral lower limb exoskeleton emulator. Dynamic Walking, Mariehamn, Åland, Finland, June 4-9, 2017. PDF

Tan, G. R., Collins, S. H. (2017) Creating controlled perturbations to study stumble recovery strategies. Dynamic Walking, Mariehamn, Åland, Finland, June 4-9, 2017. PDF

Nguyen, T., Jackson, R. W., Aucie, Y., Torres-Oviedo, G., Collins, S. H. (2017) Characterizing the relationship between step length asymmetry and metabolic rate during locomotion in post-stroke individuals. Dynamic Walking, Mariehamn, Åland, Finland, June 4-9, 2017. PDF

Poggensee, K. L., Sreenath, K., Collins, S. H. (2016) Methods to improve system identification in a human-exoskeleton system. Dynamic Walking, Holly, Michigan, USA, June 4-7, 2016. PDF

Diller, S., Majidi, C., Collins, S. H. (2016) Exoskeleton walking with a lightweight, low-power electroadhesive clutch and spring. Dynamic Walking, Holly, Michigan, USA, June 4-7, 2016. PDF

Chiu, V. L., Collins, S. H. (2016) Tripod: An ankle-foot prosthesis emulator with force control at three contact points. Dynamic Walking, Holly, Michigan, USA, June 4-7, 2016. PDF

Caputo, J. M., Dvorak, E., Shipley, K., Collins, S. H. (2016) Emulation may enable efficient personalization of conventional prosthetic feet. Dynamic Walking, Holly, Michigan, USA, June 4-7, 2016. PDF

Steele, K. M., Jackson, R. W., Collins, S. H. (2016) Increased motor module complexity with an ankle exoskeleton. Annual meeting of the American Society of Biomechanics, Raleigh, North Carolina, USA,
August 2-5, 2016. PDF

Kim, M., Collins, S. H. (2016) Step-to-step ankle push-off work modulation can reduce balance-related effort in a robotic ankle-foot prosthesis. International Conference on Intelligent Robots and Systems (IROS), Workshop on Assistance and Service Robotics in a Human Environment, Daejeon, Korea, October 9-14, 2016. PDF

Collins, S. H. (2015) Reducing the energy cost of human walking using an unpowered exoskeleton. Dynamic Walking, Columbus, Ohio, USA, July 21-24, 2015. Slides

Chen, T., Kim, M., Del Sesto, T., Collins, S. H. (2015) Inversion-eversion stiffness of ankle-foot prosthesis affects amputee's balance-related effort during walking. Dynamic Walking, Columbus, Ohio, USA, July 21-24, 2015. PDF

Del Sesto, T., Kim, M., Chen, T., Collins, S. H. (2015) Active surface matching control using an ankle-foot prosthesis emulator with two axes of torque control. Submitted to: Dynamic Walking, Columbus, Ohio, USA, July 21-24, 2015. PDF

Diller, S., Majidi, C., Collins, S. H. (2015) Clutching with high force, high bandwidth, low mass and low energy consumption using electrostatics. Dynamic Walking, Columbus, Ohio, USA, July 21-24, 2015. PDF

Emanuel, B. J., Collins, S. H. (2015) A disturbance emulation system for stability and recovery testing. Dynamic Walking, Columbus, Ohio, USA, July 21-24, 2015. PDF

Gabriel, J., Collins, S. H. (2015) Design of an agonist-antagonist knee prosthesis for experiments in human locomotion. Submitted to: Dynamic Walking, Columbus, Ohio, USA, July 21-24, 2015. PDF

Jackson, R. W., Dembia, C. L., Delp, S. L., Collins, S. H. (2015) Estimated changes in muscle-level dynamics and energetics under different levels of exoskeleton-applied work and torque. Dynamic Walking, Columbus, Ohio, USA, July 21-24, 2015. PDF

Kim, M., Chen, T., Del Sesto, T., Collins, S. H. (2015) Step-to-step ankle in/eversion torque control in a robotic ankle-foot prosthesis may reduce balance-related effort during walking. Dynamic Walking, Columbus, Ohio, USA, July 21-24, 2015. PDF

Nuckols, R. W., Collins, S. H., Sawicki, G. S. (2015) An emulator system to characterize optimal elastic ankle exoskeleton stiffness during human walking and running. Dynamic Walking, Columbus, Ohio, USA, July 21-24, 2015. PDF

Poggensee, K. L., Sreenath, K., Collins, S. H. (2015) Identifying the dynamics of a human-exoskeleton system. Dynamic Walking, Columbus, Ohio, USA, July 21-24, 2015. PDF

Rawding, K. E., Jackson, R. W., Collins, S. H. (2015) A parameter study of joint torque control during walking with bilateral ankle exoskeletons. Submitted to: Dynamic Walking, Columbus, Ohio, USA, July 21-24, 2015. PDF

Witte, K. A., Collins, S. H. (2015) Design of a comfortable pure moment knee exoskeleton. Dynamic Walking, Columbus, Ohio, USA, July 21-24, 2015. PDF

Wu, M., Adamczyk, P. G., Collins, S. H. (2015) Effort-o-Meter: The relationship between effort of walking and amount of walking performed. Dynamic Walking, Columbus, Ohio, USA, July 21-24, 2015. PDF

Zhang, J., Collins, S. H. (2015) Selecting the best series stiffness and iterative learning gains for exoskeleton torque control. Dynamic Walking, Columbus, Ohio, USA, July 21-24, 2015. PDF

Collins, S. H. (2015) Prosthetic limbs that reduce the energy cost of human walking to below non-amputee levels are possible but hard to discover Invited: Annual meeting of the American Society of Biomechanics, Columbus, Ohio, USA, August 5-8, 2015. PDF

Caputo, J. M., Adamczyk, P. G., Collins, S. H. (2015) Emulating candidate ankle-foot prostheses to inform prescription. Submitted to: Annual meeting of the American Society of Biomechanics, Columbus, Ohio, USA, August 5-8, 2015. PDF

Witte, K. A., Collins, S. H. (2015) Design of two lightweight high bandwidth torque-controlled ankle exoskeletons. Submitted to: Annual meeting of the American Society of Biomechanics, Columbus, Ohio, USA, August 5-8, 2015. PDF

Wu, M., Adamczyk, P. G., Collins, S. H. (2015) Effort-o-meter: The relationship between effort of walking and amount of walking performed. Submitted to: Annual meeting of the American Society of Biomechanics, Columbus, Ohio, USA, August 5-8, 2015. PDF

Zhang, J., Cheah, C. C., Collins, S. H. (2015) Comparison of torque controllers for an ankle exoskeleton with a series elastic actuator driven by a uni-directional Bowden cable during walking. Submitted to: Annual meeting of the American Society of Biomechanics, Columbus, Ohio, USA, August 5-8, 2015. PDF

Collins, S. H. (2015) Optimizing (artificial) ankle function during walking. Invited: Symposium on Adaptive Motion of Animals and Machines, Boston, Massachusetts, USA, June 21-25, 2015. TXT

Galle, S., Malcolm, P., Collins, S. H., Speekaert, J., De Clercq, D. (2015) Optimizing robotic exoskeletons actuation based on human neuromechanics experiments: interaction of push-off timing and work. Submitted to: Symposium on Adaptive Motion of Animals and Machines, Boston, Massachusetts, USA, June 21-25, 2015. PDF

Caputo, J. M., Collins, S. H. (2014) The effect of ankle-foot prosthesis push-off work on walking kinetics and overall effort. In proceedings: World Congress of Biomechanics, Boston, Massachusetts, USA, July 6-11, 2014. PDF

Jackson, R. W., Collins, S. H. (2014) The relative benefits of work assistance and torque assistance in ankle exoskeletons. Accepted as podium presentation: World Congress of Biomechanics, Boston, Massachussetts, USA, July 6-11, 2014. PDF

Kim, M., Tembulkar, T., Collins, S. H. (2014) Modulating prosthetic ankle push-off work at each step reduces balancing effort during walking. Accepted as podium presentation: World Congress of Biomechanics, Boston, Massachussetts, USA, July 6-11, 2014. PDF

Malcolm, P., Quesada, R., Caputo, J. M., De Clerq, D., Collins, S. H. (2014) Effect of push-off timing on metabolic cost during walking with a universal ankle-foot prosthesis emulator. Accepted as podium presentation: Dynamic Walking, Zurich, Switzerland, June 10-14, 2014. PDF

Collins, S. H., Caputo, J. M. (2013) Biomechanics-centered design of robotic lower-limb prostheses and orthoses. In: Proceedings of the annual meeting of the American Society of Biomechanics, Omaha, Nebraska, USA, September 4-7, 2013. PDF

Caputo, J. M., Collins, S. H. (2013) Quantifying the relationship between prosthesis work and metabolic rate. In: Proceedings of Dynamic Walking, Pittsburgh, Pennsylvania, USA, June 9-13, 2013. PDF

Jackson, R. W., Collins, S. H. (2013) Manipulating self-selected gait patterns with an adaptive exoskeleton. In: Proceedings of Dynamic Walking, Pittsburgh, Pennsylvania, USA, June 9-13, 2013. PDF

Kim, M., Collins, S. H. (2013) Ankle push-off is equally important to foot placement in stabilizing three-dimensional walking. In: Proceedings of Dynamic Walking, Pittsburgh, Pennsylvania, USA, June 9-13, 2013. PDF

Collins, S. H. (2012) Towards tip-top testbeds: Biomechatronics for accelerated development of assistive devices. In: Proceedings of the annual meeting of the Canadian Society of Biomechanics, Vancouver, Canada, June 6-9, 2014. PDF

Caputo, J. M., Collins, S. H. (2012) An externally powered and controlled ankle-foot prosthesis for use in push-off experiments. In: Proceedings of the annual meeting of the American Society of Biomechanics, Gainesville, Florida, USA, August 15-18, 2012. PDF

Eicholtz, M. R., Collins, S. H. (2012) Two-dimensional parameter study to characterize performance of ankle-foot orthosis joint impedance control. In: Proceedings of the annual meeting of the American Society of Biomechanics, Gainesville, Florida, USA, August 15-18, 2012.

Jackson, R. W., Collins, S. H. (2012) Targeting specific muscles for rehabilitation with an EMG-controlled ankle-foot orthosis. In: Proceedings of the Conference on Dynamic Walking, Pensacola, Florida, USA, May 21-25, 2012. PDF

Kim, M. H., Collins, S. H. (2012) Ankle control design to enhance sagittal stability for lower-limb amputees. In: Proceedings of the Conference on Dynamic Walking, Pensacola, Florida, USA, May 21-25, 2012. PDF

Caputo, J. M., Collins, S. H. (2011) Externally powered and controlled ankle-foot prosthesis. In: Proceedings of the Conference on Dynamic Walking, Jena, Germany, July 18-21, 2011. PDF

Eicholtz, M. R., Collins, S. H. (2011) Design of a portable, lightweight ankle-foot orthosis (AFO) to reduce metabolic cost of walking. In: Proceedings of the Conference on Dynamic Walking, Jena, Germany, Germany, July 18-21, 2011. PDF

Collins, S. H. (2011) Exploring ankle control strategies with an experimental biomechatronic testbed. In: Proc. Conf. on Dynamic Walking, Jena, Germany, Germany, July 18-21, 2011.


Thanks to Gordon Composites for donating fiberglass spring materials for prosthesis and orthosis fabrication.

Prior publications by Prof. Collins are available at his personal site.