Pointing Angle Estimation for Human-Robot Interface

Abstract

In this paper, we propose an approach to track and estimate user pointing direction in 3D Space. In the area of human-robot interaction, user communicates with service robot in their daily life activities to give commands and execute the given task accordingly. Therefore, the ability of user to gives command to service robot naturally can provide an interactive user interface system for real 3D space environment. For this purpose, we aim to perform pointing gesture tracking and after that estimate the user's pointing direction. Our method of pointing direction estimation is based on 3D orientation of hand and shoulder center of user. We make comparison with our previous method to find the best hypothesis. Experimental results show the angular error for the estimation of pointing direction is successfully improved from our previous method. As a result, our natural user interface system can manipulate 3D objects in living room environment thus providing intuitive robotic service for human robot interaction. I. INTRODUCTION Tracking of human gesture has been widely researched either in human-computer interaction or human-robot interaction. Besides voice, gesture is an example of platform to interfacing between human and robot intuitively and naturally. Pointing is one part of gesture which provides information and intention from human to service robot. Pointing-based user interface can easily indicate object and location for the robot delivering robot task in home environment. However, in the real environment, some ambiguity can occur and affect the performance of robotics service. The ambiguity in pointing gesture comes from the angular error in estimation of user's pointing direction particularly when certain objects is closely located. Due to the ambiguous pointing command, correct object and location cannot be identified thus service robot surely unable to deliver task successfully. To overcome this problem, we conduct several experiments on tracking of pointing arm and make comparison study to find the best hypothesis. In this paper, we present a robust tracking method to be used in pointing direction estimation. We measure the pointing angle from the position of hand with respect to the shoulder center. To obtain the 3D coordinates of pointing arm