Electroadhesive Clutch

light-weight end-effector

bowden-cabletransmission

motor and controller

Universal Device Emulators Work vs. Torque AssistanceAnkle Exoskeleton End-Effectors

Unpowered Exoskeleton

Human-in-the-Loop Optimization

Discovering Exoskeleton Control Strategies that Augment Locomotor Performance

Rachel W. Jackson and Steve H. Collins Experimental Biomechatronics Lab, Carnegie Mellon University

Outstanding mechatronic performance; versatile experimental tools

Off-board motor and control hardware; flexible tether to end-effector

Lightweight, instrumented, comfortable

High peak torque and bandwidth; low torque tracking errors

Comparison of Torque Control MethodsProportional control with damping injection compensated by iterative learning is best!

Acknowledgments

Easier to derive benefit with work input

Subtle differences in assistance matter

Device behavior systematically varied during use to maximize human performance

Algorithm: Discover device control parameters that minimize metabolic rate

Electrostatic adhesion between dielectric-coated, thin electrode sheets

High torque density; low power consumption

Lightweight, elastic device uses mechanical clutch to engage and disengage spring

Reduces metabolic cost of walking by 7%! Josh Caputo

Tiayao Chen

Vincent Chiu

Lizmarie C. Ortiz

Stuart Diller

Evan Dvorak

Blair Emanuel

Pieter Fiers

James Gabriel

Rachel Jackson

Myunghee Kim

Philippe Malcolm

Biju Oobi

Michiel Plooij

Katherine Poggensee

Roberto Quesada

Kirby Witte

Juanjuan Zhang

This material is based upon work supported by the Na t iona l Sc ience Foundation under Grant No. IIS-1355716

And many others…

References: Zhang, J., Cheah, C. C., and Collins, S. H. (2016) Torque control in legged locomotion. In Bio-Inspired Legged Locomotion: Concepts, Control and Implementation, eds. Sharbafi, M., Seyfarth, A., Elsevier, in press; 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; 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; 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; Caputo, J. M., Collins, S. H. (2014) A universal ankle-foot prosthesis emulator for human locomotion experiments. Journal of Biomechanical Engineering, 136:035002; 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.

[Caputo & Collins (2014) J. Biomech. Eng.]

[Witte et al. (2015) ICRA] [Jackson & Collins (2015) J. Appl. Physiol.]

[Zhang et al. (2014) Bio-Insp. Legged Locomotion] [Zhang et al. in preparation]

[Diller et al. (2016) ICRA] [Collins et al. (2015) Nature]