Effects of Visual Deprivation on Gait Stability During Treadmill Walking: Insights from a Bipedal Model

Walking, a fundamental daily activity, relies on sensory input from the somatosensory, visual, and vestibular systems, with vision playing a key role in providing information. When vision is impaired, individuals adjust their walking patterns to maintain stability. This study developed a simplified sagittal model to examine how visual deprivation affects treadmill walking at a controlled speed while ensuring dynamic stability. The model provides a framework for exploring outcomes that are challenging to assess experimentally. We hypothesized that the model would align with experimental data on step frequency, step length, and stability while predicting the steps that could lead to falls without vision. This study presents a bipedal model with two degrees of freedom, controlled by a hierarchical system. Two bio-inspired constraints were implemented: a speed constraint to match with treadmill pace, and a stability constraint to maintain walking stability. The weight of the feedback signal related to joint angles was modified to simulate vision loss. Visual deprivation increased step frequency and decreased step length to prevent falls. Additionally, prolonged deprivation led to step length fluctuations and increased constraint errors, ultimately causing falls. These findings align with human data, validating the potential of the model for rehabilitation research in individuals with visual impairments.