Figure 4. Simplified biomechanical human body model for estimating CoM trajectory. (a) one-link model: in this model we assumed that CoM is equivalent to lower back motion. (b) two-link model: In this model we assumed human body as two rigid segments, one rotating around ankle and the other one rotating around hip joint. (c) three-link model: in this model we modelled human body as three rigid segments rotating around ankle, knee, and hip joints.