Walking Gait Planning And Stability Control

Research on biped humanoid robots is currently one of the most exciting topics in the field of robotics and there are many ongoing projects. Because the walking of humanoid robot is complex dynamics inverse problem the pattern generation and dynamic simulation are extensive discussed. Many different models are proposed to simple the calculation. Many researches about the walking stability and pattern generation of biped robots are made using ZMP principle and other different methods. Vukobratovic first proposed the concept of the ZMP (Zero Moment Point). Yoneda etc proposed another criterion of "Tumble Stability Criterion" for integrated locomotion and manipulation systems. Goswami proposed the FRI (Foot Rotation Indicator). As for the pushing manipulation, Harada researched the mechanics of the pushed object. Some researches mentioned that changes of angular momentum of biped robot play the key roles on the stability maintenance. However, there have been fewer researches on stability maintenance considering the reaction with external environment. A loss of stability might result a potentially disastrous consequence for robot. Hence man has to track robot stability at every instant special under the external disturbance. For this purpose we need to evaluate quantity the danger extent of instability. Rotational equilibrium of the foot is therefore an important criterion for the evaluation and control of gait and postural stability in biped robots. In this paper by introducing a concept of fictitious zero-moment (FZMP), a method to maintain the whole body stability of robot under disturbance is presented.