本論文分析機器人腳與地面的彈性接觸，探討可能造成雙足機器人行走時發生傾倒及滑動的外力大小。若機器人腳所受外力矩較大，可能使腳與地面的接觸面積僅剩最後微小的區域，這就是發生傾倒不穩定的臨界狀態；而機器人在運動過程中，亦可能同時在地面上發生滑動。本研究針對滑動不穩定狀態進行分析，找出所有造成滑動臨界狀態的力及力矩(Fx, Fy, Mz)組合，並且亦找出數個造成傾倒臨界狀態的力及力矩組合(Mx, My, Fz)。分析的方法分成兩部分，第一部分是進行接觸分析，求出外力(矩)作用之下接觸面積及壓力分布。此部分結果可找出造成傾倒臨界狀態之(Mx, My, Fz)組合。第二部分是在接觸區域及正向壓力求出之後，利用平面運動之瞬時中心的觀念，找出滑動臨界狀態之(Fx, Fy, Mz)組合。 In this thesis the elastic contact between a robot foot and ground is analyzed to investigate the forces to cause falling or sliding of a biped robot in walking. In cases with large applied moments, the foot-to-ground contact area may reduce to a very small region, and this is the critical condition for falling. Gross sliding may also occur during robot walking, which is also a state of instability. In this thesis the size of foot-to contact region and pressure distribution in the region is determined first, from which the tangential stress distribution may also be found by using the technique of instantaneous center of zero velocity. With these stress distributions the resultant moments in gross sliding or falling may be determined. In this thesis we show all combinations of forces (moments) (Fx, Fy, Mz) to cause sliding, and a few combinations of forces (Mx, My, Fz) to cause falling. These forces are compared with results obtained by treating the foot as a rigid body.
