Yaw moment compensation by using full body motion

This paper describes a generalized approach for compensating the net yaw moment of a humanoid robot about the Zero Moment Point while performing an arbitrary motion. The proposed algorithm makes it possible to prevent unwanted / unexpected yaw rotations by compensating the net yaw moment about the Zero Moment Point using “free” joints that are unrelated to the required task motion. For example, for a walking motion the joints of the chest, neck and arms may not have an assigned task, and can be used in combination to provide such compensation. Finally, some simulation results are provided, which intend to show the validity of this approach.

I. Introduction

Humanoid robots' most important characteristic is that they have a non-fixed base that allows them to freely move in the environment by means of bipedal locomotion. This also brings the drawback that slippage is induced due to undesired excessive yaw moment on the feet, which results in an undesired rotation that may deviate the humanoid robot from its desired path [1].