Figure 3.

Stance-phase patterns of walking at about 1.2 m s⁻¹. (A–C) Examples of three characteristic steady-state solutions of the bipedal spring–mass model are compared with (exp) experimental results (mean and s.d. shown as line and shaded area) of five subjects (mean±s.d. of mass: 81±3.5 kg, leg length: 1.07±0.03 m) walking on a treadmill (Adal3D, TecMachine, France; with force sensors recording horizontal and vertical GRFs). The subplots show horizontal and vertical GRFs, F_x and F_y; vertical displacement, Δy; and changes in forward kinetic and gravitational potential energies, ΔE_k,x and ΔE_p. The vertical displacement is compared with that of an inverted pendulum (dashed line). The shaded segments at the time-scales denote double supports. The depicted lengths of the time-scales reflect the absolute stance times.