Human-in-the-loop Optimization: (A) Measurements of human performance are used to update device control so as to improve performance in the human portion of the system. (B) A method for minimizing the energy cost of human walking, in which various control laws are applied, metabolic rate is quickly estimated for each, costs are compared, and an evolution strategy is used to generate a new set of control laws to be tested, all during walking. Click for high-resolution version. Image credit: Steve Collins.


Ankle Exoskeleton Emulator: Click for high-resolution version. Image credit: Carnegie Mellon University.

 
Ankle Exoskeletons: Left: Exoskeleton worn on one ankle in the main experiment. Right: Exoskeletons worn on both ankles in the single-subject studies. Detailed designs in Witte et al. (2015). Click for high-resolution images. Image credit: Kirby Witte, Katie Poggensee, Pieter Fiers, Patrick Franks and Steve Collins.

 
Ankle Exoskeleton: Design described in detail by Witte et al. (2015). Click for high-resolution versions. Image credit: Kirby Witte, Katie Poggensee, Pieter Fiers, Patrick Franks and Steve Collins.

 
Experimental Setup: The emulator system consists of: (1) a large off-board motor; (2) a tether, comprising a Bowden cable transmission and sensor wires; (3) an exoskeleton worn on leg; and (4) a real-time control computer. Participants walk on (5) an instrumented split-belt treadmill with (6) emergency stop buttons while wearing (7) a safety harness and (8) a respirometry mask to measure metabolic rate. The experimenter used (9) an interface computer to control the system. Emulator approach described in Caputo & Collins (2014). Ankle exoskeleton emulator described in Witte et al. (2015). Click for high-resolution versions. Image credit: Kirby Witte, Katie Poggensee, Pieter Fiers, Patrick Franks and Steve Collins.