The article analyses a model of single degree of freedom inverted pendulum controlled by proportional, integral and differential (PID) controller which is used to stimulate the vibration of pressure center (COP) of the human body in forward-backward direction during still standing. Numerical experiments revealed that certain traditionally used approaches of the disturbance torque generation should be reconsidered when parameters of a particular human are being identified. The article presents a new disturbance torque generation approach based on the components frequency analysis of the center mass vibration (COM).