  Human posture control models are used to analyse neurological experiments and
control of humanoid robots. This work focuses on a well-known nonlinear posture
control model, the DEC (Disturbance estimate and Compensation). In order to
compensate disturbances, unlike other models, DEC feedbacks signals coming from
sensor fusion rather than raw sensory signals. In previous works, the DEC model
is shown to predict human behavior and to provide a control system for
humanoids. In this work, the stability of the system in the sense of Lyapunov
is formally analysed. The theoretical findings are combined with simulation
results, in which an external perturbation of the support surface reproduces a
typical scenario in posture control experiments.
