Comparison Study of Two Inverted Pendulum Models for Balance Recovery

The inverted pendulum model (IPM) represents better a human-like gait, however, its nonlinearity introduced by the impact during the change of support leg prevents its implementation. The analytic feature of the Linear Inverted Pendulum Model (LIPM) makes it widely applied for the bipedal gait control and balance recovery. We resolve the analytic solution issue for the IPM by using the principle orders in the Taylor series, and further prove the predictive properties of both models. Our theoretical and simulation studies quantitatively compare these two models on the prediction of the target foot placement and allowable swing time. The dynamic simulation and preliminary experiments validated the effectiveness of the IPM based foot placement control.