Study of Gait Cycle Using a Five-Link Inverted Pendulum Model: First Developments

Gait cycle has been the target of many studies in the last decades in order to identify the normal and pathological gait patterns of humans. The usefulness of these studies is of utmost importance in the robotics field to construct mathematical models in order to simulate the inclusion of assistive robotic devices during the human walking movement. In this work, a five-link inverted pendulum model based on Euler-Lagrange equations with 5 degrees of freedom (DOFs) in the sagittal plane was developed with the main purpose to concern stability during gait cycle. This study also involved the gait data acquisition from healthy gait patterns using a motion tracking system and force plates, allowing, in a future work, the validation of the model constructed. The results showed correlations above 0.90 between the collected joint angles and moments and the data presented in literature, validating the performed data acquisition. Future challenges include the model validation and the application of strategies of control. An analysis of the stiffness variation with the power and speed during the human walking motion is also proposed.