Concerning the change of slopes, a control strategy is proposed to make the passive dynamic walker realize
the switch of walking mode with low energy dissipation in finite time. The alter cell to cell mapping method based on cell
mapping theory is proposed to estimate the initial state of the stable gaits. Then the switch controller between different
slopes is designed based on Lyapunov stability theory and robust control theory. This controller can accomplish the switch
between different gaits for different slopes efficiently and improve the robustness of switch process. Simulation results show
the effectiveness of the control strategy.