1. Introduction
Human action recognition has been studied for a decade in the related literature, including computer vision, robotics, surveillance, virtual reality, and so on [1]–[2]. Although a lot of methods for human motion recognition have been proposed with various sensors and algorithms different to each other and some of methods have been successfully applied to real-life applications, human motion recognition is still one of challenging issues due to the very large diversity of general human actions. Therefore, it is technically very difficult to generalize one method based on one approach for recognizing all kinds of human actions.