J Intell Robot Syst (2011) 63:211–231 DOI 10.1007/s10846-010-9525-5 Human-and-Humanoid Postures Under External Disturbances: Modeling, Simulation, and Robustness. Part 2: Simulation and Robustness Miomir Vukobratovic · Milena Milojevic · Spyros Tzafestas · Milos Jovanovic · Veljko Potkonjak Received: 21 October 2010 / Accepted: 8 December 2010 / Published online: 14 January 2011 © Springer Science+Business Media B.V. 2011 Abstract The sophisticated method for mathematical modeling of humanoid robots formulated in Part 1 of this paper is applied here to the dynamic task of keeping a posture under disturbance, which is equally important to humans and humanoid robots. The idea of this work is to develop and realize a simulator tool for dynamic analysis of human-or-humanoid behavior under disturbances. To show the potentials and verify this tool, we comparatively analyze the robustness of some postures to external disturbance. At this stage of research we do not conduct real experiments with humans/humanoids but try to verify our simulation tool by relying on available experience. Therefore, the postures for comparison are taken from everyday life and from sports: upright standing, squat posture, and three karate postures. As the external disturbance we choose an impulse and a permanent force, both with variable direction and magnitude. Keywords Posture · Robustness · Disturbance · Dynamic model · Simulation M. Vukobratovic · M. Milojevic · M. Jovanovic Institute “Mihajlo Pupin”, Volgina 15, 11000 Belgrade, Serbia M. Vukobratovic e-mail: vuk@robot.imp.bg.ac.rs M. Milojevic e-mail: milenamilojevic@live.com M. Jovanovic e-mail: milos@robot.imp.bg.ac.rs S. Tzafestas Nacional Technical University of Athens, Zographou, 15773, Athens, Greece e-mail: tzafesta@softlab.ntua.gr V. Potkonjak (B ) Faculty of Electrical Engineering, University of Belgrade, Bulevar Kralja Aleksandra 73, 11000 Belgrade, Serbia e-mail: potkonjak@yahoo.com