Balance impairment is one of the major contributors to fall, frequently amenable to surgical intervention. Repeated falls can lead to bad injuries which can decrease or even stop the professional and social activities. The study of the static equilibrium is an easy method to quantify the physical/functional status of a person, which can help physicians to establish the diagnostic. In this study, body sway was assessed using 3D inertial sensors (accelerometers and gyroscopes). Based on recorded kinematical signals under different measurement protocols (e.g. eyes open/eyes closed), the goal was to find parameters able to objectively discriminate subjects with low equilibrium skills from the others. The kinematical equilibrium parameters were estimated using different linear/nonlinear signal processing methods. The results of eyes open/eyes closed measurements gave a better understanding of the interaction of the biological sensors used by the body to regulate the equilibrium. The linear analysis study provided a first approach of the main kinematical parameters to discriminate the participants in the study. Finally, the nonlinear analysis provided new parameters discriminating better the physical performances of participants even if some overlap in the participants' data persist