Experimental protocol.

<p>The stepping constraints are illustrated from the perspective of P8 before she started walking at the start of each trial. Typically P8 would require 5–7 steps between initiating gait at the starting position and stepping in the first stepping guide. The centres of both the foot and stepping guide were calculated as the intercept between the medio-lateral and anterior-posterior coordinates of each, as illustrated by the black dotted lines. The red arrow represents the absolute error of foot placement in the stepping guide, calculated as the distance between the central positions of the foot and stepping guide.