Fig. 2.

Gait animation (top left), conserved quantity errors (top right), joint trajectory (middle left), phase portrait (middle right), saturated control torques (lower middle left), yaw friction torque (lower middle right), vertical ground reaction force (bottom left), and Coulomb friction ratios (bottom right). A supplemental downloadable movie of this 3D walking simulation is available at: http://vimeo.com/20956363.

Model : M_t = 15 kg, ℓ_t = 0.55 m, M_h = 10 kg, m = 5 kg, m_th = 0.7m, m_sh = 0.3m, ℓ = 1 m, α = 0.5, w = 0.2 m, ρ = 0.0564 rad

Gains : K₁ = 0.5, K₂ = 25, L = 68, k_p = 700, k_d = 265, β = 0.06 rad, U_max = 40 Nm

x^* ≈ (−0.0741, −0.0016, 0.3089, −0.0498, −0.3084, −0.3084, 0.2008, 0.0450, −0.8307, −1.1639, 0.7324, 0.7324)^T