On How Compliant Feet Support Postural Stability in Two Legged Locomotion

Humanoidal robots are complex systems with many sensors, many degrees of freedom and many control signals. Those robots to move autonomously have to be powered by on-board batteries. Proper design of their mechanical structure is of paramount importance - it can improve the robot performance, increasing its mobility and decreasing the energy consumption. This can be achieved in many ways, among others by introducing compliance into its feet or legs. In this paper a method for evaluating the distribution of forces acting on a foot are presented. This is needed for adequate design of efficient compliant robotic feet. It is shown that proper selection of the foot stiffness enhances body stability and potentially eliminates the need for the upper body sway. The results of computations are provided and discussed.