... ankle, knee, and hip angles (Fig 1); toe vertical dis- placement, vertical velocity, and hori- zontal velocity (Fig 2); ankle, knee, hip, and support moments (Fig 3); and ankle, knee, and hip ... foot and continuing up to the hip, across the pelvis, and down the swing limb, and the chain involves at least 12 degrees of freedom at the joints and scores of muscles. The gen- eration and ... (safe toe clearance and a gentle foot land- ing) present a challenge to the central nervous system during walking. The HAT constitutes two thirds of the body mass, and the HAT'S center...