Figure 2
From: Evaluating the energetics of entrainment in a human–machine coupled oscillator system
Experimental protocol. (a) A generic trial condition is depicted with example step frequency data over time (magenta) and constant motor frequency (blue). Subjects walk with no oscillations during the first 2 min of the test. Motor oscillations begin at time zero and continue for 5 min while subjects freely interact with the system. Oscillations continue for another 5 min, but now a metronome directs individuals to step at their baseline preferred frequency (\(f_{p}\)) despite the external oscillation frequency (“frequency clamping”). The oscillations and metronome are terminated, and the subject is given fifteen additional seconds to prepare for the end of the trial. (b) Baseline conditions and oscillation parameters prescribed to the system during experiment trials are shown: \({\Delta }f_{m}\) is the percent difference in oscillation frequency relative to subjects’ baseline preferred step frequency (\({\Delta }f_{m} = 0, \pm 6\%\)) and \(A_{m}\) is the oscillation amplitude expressed in units of subject body weight (BW) (\(A_{m} = 10, 30\%\)). Trial conditions were implemented randomly to reduce ordering effects.
