Modelling Dynamic Postural Stability Margins during Fixed-Support Balance Recovery

This dissertation is an investigation into the use of whole-body center of mass (CoM) dynamics for evaluation of balance control following robotic platform perturbations evoking fixed base of support postural strategies. Two primary purposes were identified: i) ascertain the effects of anthropometric model reductions on estimations of extrapolated CoM-based margins of stability (MoS); and ii) develop a biomechanical model to evaluate changes in dynamic MoS when accounting for both a counterbalance postural strategy and platform perturbation. Experimental data collection and analyses (kinematics) of young adults responding to perturbations in addition to forward dynamics simulations of the proposed model suggested the following: i) the degree of anthropometric simplicity sufficient for CoM estimates depends on the perturbations utilized; ii) counterbalance strategies produce a larger feasible MoS relative to those derived using an inverted pendulum model. Thus, these findings highlight the importance of considering the postural task/mechanics when using CoM based stability metrics.