Identification of Sensory Dead Zones in Human Balancing on Balance Board

A two-degree-of-freedom mechanical model was developed to analyze human balancing on rolling balance board in the sagittal plane. The human nervous system is modeled as a delayed proportional-derivative feedback mechanism involving the dead zones of the visual, vestibular and proprioceptive systems. The goal of the paper is to determine the threshold of the sensory perception for angle offset and angular velocity. Simulation of the linearized system was performed with different sizes of dead zone, and the standard deviation of the amplitude of the arising fluctuation and its derivative was calculated and compared with balancing trials recorded by OptiTrack motion capture system. It can be concluded, that the threshold of the sensory organs is in the range of $0.01\sim 0.07^{\mathrm{o}}$ for angle, and $0.01\sim 0.10^{\mathrm{o}}/\mathbf{s}$ for angular velocity.