Motion perception and classification are key elements exploited by humans for recognizing actions. The same principles can serve as a basis for building cognitive architectures which can recognize human actions, thus enhancing challenging applications such as human robot interaction, visual surveillance, content-based video analysis and motion capture. In this paper, we propose an autonomous system for real-time human action recognition based on 3D motion flow estimation. We exploit colored point cloud data acquired with a Microsoft Kinect and we summarize the motion information by means of a 3D grid-based descriptor. Finally, temporal sequences of descriptors are classified with the Nearest Neighbor technique. We also present a newly creat...