Humanoids walk with feedforward dynamic pattern and feedback sensory reflection

Since a biped humanoid inherently suffers from instability and always risks itself to tipping over, ensuring high stability and reliability of walk is one of the most important goals. This paper proposes a walk control consisting of a feedforward dynamic pattern and a feedback sensory reflex. The dynamic pattern is a rhythmic and periodic motion, which satisfies the constraints of dynamic stability and ground conditions, and is generated assuming that the models of the humanoid and the environment are known. The sensory reflex is a simple, but rapid motion programmed in respect to sensory information. The sensory reflex, we propose in this paper, consists of the body posture control, the actual ZMP (Zero Moment Point) control, and the landing time control. With the dynamic pattern and the sensory reflex, it is possible for the humanoid to walk rhythmically and to adapt itself to environmental uncertainties. The effectiveness of our proposed method was confirmed by walk experiments of an actual 26 DOF hum anoid on an unknown rough terrain and in the presence of disturbances.