Model of human balance control. The model consists of body mechanics and a controller with intrinsic stiffness and damping (Cpas), an active proportional derivative controller (Cact), timedelays (δ), muscle activation dynamics (Hact), sensor and measurement noise. Tank and Thip denote the respective joint torques, θ1 and θ2 the joint angles. Sx and Fpert are the force and platform perturbations, respectively. g is the gravitational acceleration.
Boonstra et al. Journal of NeuroEngineering and Rehabilitation 2013 10:23 doi:10.1186/1743-0003-10-23