Stability analyses of visual-lifting biped walking based on feedforward and feedback calculation

The fields of robotics and control are making effort to develop biped robots that can realize walking motions with the stability and flexibility like humans'. Dynamic walking models of biped robots are hybrid in nature. In previous study, biped walking control has been realized by Zero-Moment Point (ZMP). The efficiency of ZMP was well verified in keeping stable walking, but ZMP based walking cannot stop falling down when the gait is tiptoe state. Besides, dynamical walking can be used for walking that realizes kicks by toes, which does not depend on ZMP. Though the dynamical walking seems to be natural, robots tend to fall down. Therefore, it is necessary to keep the stability of dynamical walking. In our study, we have proposed a dynamical equation for walking derived by the Newton-Euler method including slipping, impact, point-Touchdown and surface-Touchdown of the foot. ' Visual Lifting Approach ' (VLA) can enhance the stability of standing and walking and prevents bipeds from falling without using ZMP. The combined control includes visual-lifting feedback and swinging feedforward, which can realize the switch of walking gaits. In this paper, we analyze the realization of the stable walking according to some dynamical measurements.