Global-Position Tracking Control of a Fully Actuated NAO Bipedal Walking Robot

The ability to reliably track various planned paths with specific timing, which is termed as the global-position tracking capability in this paper, is essential to highly versatile bipedal robotic walking. To provably guarantee global-position tracking performance for fully actuated bipedal robots, this study proposes a time-dependent state-feedback control strategy based on a) a full-order model of the hybrid, nonlinear, floating-based bipedal walking dynamics, b) time-dependent input-output linearization, and c) Lyapunov-based stability analysis. This study also provides general guidelines for adapting the proposed control strategy to walking experiments in the presence of a common hardware limitation of bipedal robots, which will help to bridge the gap between theory and experiment in bipedal walking control. Simulations and experiments on a NAO bipedal robot were performed to demonstrate the effectiveness of the proposed walking control strategy.