Redirected walking has been proposed as a means of making a narrow space feel wide in a virtual space. We examined the effect of visuo-haptics on the detection threshold of rotation gain when participants walked around a wall. We found that the threshold was affected by visuo-haptics only when they walked around the outside of the wall but was not affected when they walked around the inside of the wall.

Teleoperation is a very useful technique in the case of carrying out tasks in hazardous and/or remote sites. In order to carry out the tasks in high operational efficiency, a video system to display the workspace for an operator is important. In this study, we developed a spatial multi-resolution stereoscopic video system which has variable convergence point, and confirmed the effect of keeping an overlapped area large at the working point by varying the convergence point continuously with the spatial multi-resolution stereoscopic video system. As the results of this experiment, it was clarified that the operational efficiency with teleoperation through the spatial multi-resolution stereoscopic video system was improved by keeping an overlapped area large, which resulted from varying the convergence point. That is, in order to carry out tasks with teleoperation in high operational efficiency, the system is required to vary its convergence point to keep an overlapped area large.

Today's computing and networking technologies allow people to have asynchronous on-line discussions by exchanging messages. Typical discussion base systems also provide discussion logs as archives or histories of the messages. Reviewing a discussion log raises several issues; the discussion log can include not only noteworthy messages but also worthless ones, while it does not include tacit understandings and external information mentioned by the discussion. The authors have been developing a system that implements techniques for solving these issues. This paper introduces the techniques implemented in the systems and describes the authors' findings.

Our pilot study suggested that while fixating on a stationary object binocularly, each line of sight of the two eyes does not always go directly toward the object. Therefore, we experimentally investigated the amount of the displacement of the pupil center while the fixation point was changed transversally. The subjects were instructed to fixate on three targets arranged horizontally with intervals of nine degrees. The distance from the subject to the targets was any of 0.5 m, 1.0 m and 1.5 m. A significant difference of the amount of the displacement of the pupil center was observed relative to the fixation distance. The positions of the node of the line of sight, which provide no relationship between the fixation distance and the pupil center displacement, were calculated. The node of the line of sight of the non-dominant eye was nearer to the fixation panels than that of the dominant eye. Considering this, such a node would be effective for the precise measurement of gazing point.

We developed a stereoscopic video system, which has high-resolution images for central vision and it is called the Q system. The Q system uses a compound image that is a wide-angle image with an embedded high-resolution image. However, the Q system could not be used under situations where many robots work at the same time. This is because it needs four channels of video signals and the available channels could be limited under such situations. Thus, we have developed a digital Q system. The system can be used under such restricted situations, because the required data transfer rate is adjustable by changing the compression rates for a high-resolution image and a wide-angle image. In addition, an experiment confirmed that even though the systems used the same data transfer rate, digital Q system could make teleoperation more efficient and more precise than a conventional stereoscopic video system.

Teleoperation requires both wide vision to recognize a whole workspace and fine vision to recognize the precise structure of objects which an operator wants to see. In order to achieve high operational efficiency in teleoperation, we have developed the Q stereoscopic video system which is constructed of four sets of video cameras and monitors. It requires four video channels to transmit video signals. However, four channels are not always available for a video system because of the limitation of the number of radio channels when multiple systems are used at the same time. Therefore we have tried to reduce the number of channels on this system by sending images from the right and left cameras alternately by field. In experiment 1, we compared the acuity of depth perception under three kinds of stereoscopic video systems, the original Q stereoscopic video system, the Q stereoscopic video system with two channel transmission, and the conventional stereoscopic video system. As the result of the experiment, the original Q stereoscopic video system enabled us to perceive depth most precisely, the Q stereoscopic video system with two channel transmission less so, and the conventional stereoscopic video system even less. In experiment 2, we compared the Q stereoscopic video system with two channel transmission to the original Q stereoscopic video system. The result showed that the operators were able to work more efficiently under the original Q stereoscopic video system than under the Q stereoscopic video system with two channel transmissions. In experiment 3, we compared the Q stereoscopic video system with two channel transmission to the conventional stereoscopic video system. It was found out in this study that the new stereoscopic video system we developed enabled operators to work more efficiently and to perceive depth more precisely than the conventional stereoscopic video system, although the number of channels for image transmission of this system was equal to that of the conventional stereoscopic video system.