Figure 5
Geometric Trajectory of the Boot-Pedal System. Definitions of top dead center (TDC), bottom dead center (BDC), and reference frames for the boot-pedal (ϕ; Xp, Yp) and ground (Φ; Xc, Yc). θp corresponds to boot-pedal angle relative to the horizontal and θc corresponds to crank angle relative to the vertical axis. Leg flexion occurred from 110°–290°, leg extension occurred from 290°-110° of the crank angle.