Analogy between Passive walking robot and Phase Locked Loop circuit

Recently many walking robots are developed, and almost all the researches adopt the model-based control. However the researches also adopt other ideas based on the dynamics-based control to decrease their energy consumption, to absorb the impact shock of contacting etc. So it seems important and valuable for the conventional walking robot control method to import the ideas based on the dynamics. On the other hand, we focus the passive dynamic walking robot system which walks only by the dynamics. If the principle of the passive dynamic walking robot system is analyzed and elucidated, we are able to apply the essence of the system to the conventional walking robot control, and also contribute the performance gain. In this paper we analyze the behavior of the passive walking robot system via analogy between the phase locked loop circuit and the passive walking robot system, and we ascertain that both of them bifurcate and show chaotic behavior on the same condition. Then, for the purpose of the above, we show the effectiveness of the analysis result for the passive dynamic walking robot design