Analysis of Mechanical Structure and Stability for a Humanoid Robot

Abstract

This paper describes our preliminary research in analyzing mechanical structure and its stability of a humanoid robot, being designed and built at FIBO. Mobility and gaits of such a robot are governed by only two legs, leading to high complexity in dynamic control. We have thoroughly measured positions, velocities and accelerations of each joint at human legs in order to understand their profiles. We are in a process of designing geometry of the robot legs, based on such measured profiles. In addition, we have proposed robot gaits with related analysis on kinematic and dynamic stability. Finally, a planar two degree of freedom inverted pendulum (PTIP) has been built as a testbed to implement the state feedback controller. PTIP is considered a preliminary balancing prototype. When the system is disturbed, it can recover its stability under the time about 12 seconds. After that we increase 1.7 times of original mass to the system and disturbed it again. the system has more vibrate and slow response, which use a time to recover its stability about 30 seconds.