Fig 3. Experimental Evaluation.

“Body-in-the-Loop” optimization refers to the use of real-time measures of a physiological value function to drive the online selection of parameter values. We evaluated this concept with the example of treadmill walking to the beat of a metronome. In a study with eight healthy subjects, we used step-frequency as a proxy for the controller parameters of a computer controlled assistive device. Our physiological objective was the minimization of metabolic energetic cost. Three different computer algorithms were implemented that prescribed step-frequency via the metronome and that evaluated measures of oxygen consumption.