Walking control based on the SIPUP model

In our previous work, a walking pattern generator based on the spherical inverted pendulum model has been proposed. It enables to generate up-and-down waist motions and utilizes the singularity neighborhood in the middle of each support phase. However, the spherical inverted pendulum model cannot move the ZMP during each single support phase. In this paper, we propose a new approach to generate a walking pattern based on a spherical inverted pendulum model with an underfloor pivot (the SIPUP method). With this method, the ZMP gains mobility during each single-leg support phase, and walking with a smaller acceleration is achieved. In addition, it becomes easy to utilize singularity neighborhood. As a result, the knee joint can be almost fully extended (less than 0.01 rad). Experimental results show the effectiveness of our approach.