In previous studies, we developed a postural stiffness measure that is extracted from foot center-of-pressure (COP) trajectories from quietly standing individuals and is based on an analytical mechanical model of posture control. Here we apply this measure to patients with Parkinson's disease (PD). We correlated the postural stiffness measure with different clinical rating scales, obtained from...

The objective of this study was to evaluate the performance a magnetorheological-fluid-based variable stiffness actuator leg under high impact forces through optimal tuning and control damping properties. To achieve this, drop testing experiments were conducted with at various heights payload masses. results showed that while lower higher can lead greater energy dissipation, respectively, also ...

REFERENCES: Bellman, R. E. (1967). Introduction to the Mathematical Theory of Control Processes. New York: Academic Press. Bellman, R. E., Jacquez, J., Kalaba, R., & Schwimmer, S. (1976). Quasilinearization and the estimation of chemical rate constants from raw kinetic data. Mathematical Biosciences, 1, 71-76. Ferris, D. P., & Farley, C. T. (1997). Interaction of leg stiffness and surfaces stif...

Magnetic resonance elastography (MRE) is capable of noninvasively quantifying the mechanical properties of skeletal muscles in vivo. This information can be clinically useful to understand the effects of pathologies on the mechanical properties of muscle and to quantify the effects of treatment. Advances in inversion algorithms quantify muscle anisotropy in two-dimensional (2D) and three-dimens...

This paper investigates the stiffness modelling of a 3-DOF parallel manipulator with two additional legs. The stiffness model in six directions of the 3-DOF parallel manipulator with two additional legs is derived by performing condensation of DOFs for the joint connection and treatment of the fixed-end connections. Moreover, this modelling method is used to derive the stiffness model of the ma...

This paper demonstrates that any general 3-DOF three-legged planar parallel robot with extensible legs can change assembly modes without passing through parallel singularities (configurations where the mobile platform loses its stiffness). While the results are purely theoretical, this paper questions the very definition of parallel singularities.