MS11.2: Nonlinear Dynamics in Biological Systems

This work introduces a proactive approach to addressing falls by using visual feedback of predicted future balance. The study employs a mathematical model based on an inverted pendulum model. Time series realizations demonstrate that visual feedback reduces postural sway, with trust in the technology influencing effectiveness. The parametric study reveals that achieving 100% trust is not necessary for optimal effectiveness. The work emphasizes the potential of this approach to support real-time, in-situ balance improvement, providing new choices for assistive devices. The findings suggest a promising avenue for technology development to prevent falls and improve balance among individuals with impaired balance.

Understanding the mechanisms of instability in upright balance holds significant implications for the rehabilitation and prevention of falls among individuals. Our research delves into postural instability and its underlying mechanisms, achieved by intentionally manipulating neuromuscular feedback using virtual reality (VR). Using VR for feedback manipulation presents a challenging task and allows us to assess specific neuromuscular mechanisms (e.g., delay, feedback gain, muscle strength) that contribute to instability. Identifying signs of impaired balance and pinpointing the responsible mechanisms can enhance the well-being of billions of individuals, mitigating their risk of falls, preventing injuries, and promoting sustained independence.

This work details a computational model to of a rod to determine the dynamical behavior subject to non-conservative loads. The equilibrium equations and compatibility conditions of space-time continuity along with the constitutive law of a slender rod is derived following the Kirchhoff’s approach and solved together to determine the kinetics of the rod. A case of Beck’s column with follower force is examined computationally. The model is benchmarked for the critical buckling load which initiates limit cycle oscillations in the presence of hydrodynamic drag. The effect of a nonlinear softening constitutive law on the frequency response is determined as a function of parameters in the softening nonlinearity.