Getting Feedback from a Miniature Robot Yasser Mohammad Graduate School of Informatics Kyoto University Kyoto Japan yasser@ii.ist.i.kyoto-u.ac.jp Toyoaki Nishida Graduate School of Informatics Kyoto University Kyoto Japan nishida@i.kyoto-u.ac.jp ABSTRACT The HRI field of research has gained much attention re- cently because of the expected importance of well designed interaction modalities with social robots. To achieve nat- ural interaction between the robot and the human, a feed- back mechanism from the robot to the human needs to be designed that allows the robot to express its internal state to the human in a natural way. Verbal and nonverbal feed- back from humanoid robots or humanoid robotic heads have been widely studied but there is little comparable research about the possible feedback mechanisms of non-humanoid and especially miniature robots. In this paper a comparison between using verbal feedback and motion cues is conducted. The results of the experiment showed that there is no sig- nificant difference in the task completion accuracy and time or in the feeling of naturalness between these two modali- ties and there is a statistically significant improvement when using any of them compared with the no-feedback (control) case. Moreover the subjects selected the motion cues feed- back mechanism more frequently as the preferred feedback modality for them. 1. INTRODUCTION For Human-Robot Interaction to proceed in a natural way, the robot must be able to understand the human’s intention and to communicate its own internal state or intention to the human through a combined operation named mutual intention formation and maintenance [8] [5]. In a previous work, the authors proposed the interactive perception system as a way to solve the first part of the puz- zle, namely getting a hand on the human’s intention through processing sensed signals from her[4]. To solve the remain- ing part, the robot needs to find a way to communicate its own intention to the human in a natural way. If the robot has a humanoid body or face, the problem becomes how to effectively use the available degrees of freedom to generate believable feedback, but if the robot is a miniature robot that has very limited degrees of freedom the problem be- Permission to make digital or hard copies of all or part of this work for personal or classroom use is granted without fee provided that copies are not made or distributed for profit or commercial advantage and that copies bear this notice and the full citation on the first page. To copy otherwise, to republish, to post on servers or to redistribute to lists, requires prior specific permission and/or a fee. HRI ’08 Amesterdam, Netherland Copyright 2008 ACM X-XXXXX-XX-X/XX/XX ...$5.00. comes how to generate enough different feedback patterns using the limited possibilities available while keeping their meaning easily comprehendible by humans. A previous pilot experiment reported in [6] showed that using motion cues as a feedback mechanism can be a promis- ing direction. This paper presents a larger experiment to compare the effectiveness and naturalness of using motion cues as a feedback mechanism with using verbal feedback and with a control no-feedback condition. Many researchers have investigated the feedback modal- ities available to humanoid robots or humanoid heads [1] [2] [3], but the research about feedback from non-humanoid robots is still limited. In [11], acting in the environment was suggested as a feed- back mechanism. For example the robot re-executes a failed operation in the presence of a human to inform him about the reasons it failed to complete this operation in the first place. Although this is an interesting way to transfer infor- mation it is limited in use to only communicating failure. Our method of feedback by motion cues can be consid- ered in part as a generalization of the feedback by acting paradigm presented in [11], as it is not limited to failure communication. 2. DESIGN The experiment (referred to as the TalkBack experiment in this paper) is designed as a game in which a human is instructing a miniature robot using free hand gestures to help it follow a specific path to a goal in an environment that is projected on the ground. The path is only visible to the human and the robot cannot know it except through the communication with the human operator. Along the path there are some objects of different kinds as well be explained later. Those objects are not seen by the human but can be sensed by the robot using virtual short range infrared sensors, and the only way the human can give the robot the correct signals is if the robot could transfer its knowledge to her/him. The experiment was designed so that the partially observ- able environment can be converted into a completely observ- able environment if the human and the robot succeeded in exchanging their knowledge. Fig. 1 illustrates this point. 2.1 Experimental Setup A map describes both the required path that is projected on the environment and the location of different kinds of virtual objects within it. There are five types of objects that can exist in the Talk-