Parameter dependency between upper body, lower limbs, and neural systems on walking performance: a modeling study

Bipedal walking is a complex phenomenon generated through dynamic interactions between the upper body, lower limbs, and neural system. In this study, to explain the dynamic effect of these elements on walking, we propose a compass model with a vertical wobbling mass and control methods of legs imitating the neural system. The limit cycles of the model were numerically searched, and their stability, energy efficiency, and walking velocity were investigated. Consequently, specific types of solutions increased energy efficiency and walking velocity compared with a model without wobbling mass when the condition between the frequencies of the three elements satisfies the conditions for the resonance phenomenon. Moreover, we examined the relationship to actual human walking from the viewpoint of the vertical ground reaction force. We found that some solutions similar to actual human walking involved high walking performance. These results suggest that in actual human walking, three elements are adjusted appropriately in response to environmental interactions to walk efficiently.