We have developed a full-body virtual-presence system that users crawl to travel in human inner body, and learn structures of digestive organs by visual, tactile and auditory sensations. Digestive organs (esophagus, stomach, bile, small intestine, large intestine, rectum) were created in details with 3-D images that users could look around using a head-mounted display, and appropriate feelings of touches were presented to users’ abdomen and thighs by vibrotactile devices. Users’ crawling was detected by pressure sensors so that they could travel in the digestive organs while hearing realistic 3-D sounds. Participants felt as if their own body became a digested food and was moving in other’s inner body. This system may serve an interactive education contents of human inner body.

We explore Redirected Jumping, a novel redirection technique which enables us to purposefully manipulate the mapping of the user’s physical jumping movements (e.g. distance and direction) to movements in the virtual space, allowing richer and more active physical VR experiences within a limited tracking area. To demonstrate the possibilities provided by Redirected Jumping, we implemented jumping redirection methods for three basic jumping actions (i.e., horizontal, vertical, and rotational jumps) using common VR devices. We conducted three user studies to investigate the effective manipulation ranges, and the results revealed that our methods can manipulate a user’s jumping movements without them noticing, similar to redirected walking.

We feel as if a fake body is our own body by synchronicity between the fake body and the real body (illusory body ownership). The illusory body ownership can be induced to an invisible full body via the synchronous movement of only the hands and feet. We aimed to investigate whether the illusory ownership occurs to a virtual body with an elongated arm by changing position of the one of the hands, and it changes reaching behavior and/or postural stability. We found that the illusory body ownership was induced to the transformed body by synchronous movement of the hands and feet. Participants’ reaching behavior gradually changed to use the longer arm more than the normal arm during learning of the transformed body within 10 min. Postural stability did not change. These results suggest that we can have illusory ownership of the transformed body with the elongated arm, and our behavior adaptively changes to utilize the new body.

We conducted an experiment presenting a vection stimulus by HMD and a scent stimulus by olfactory display to investigate the interaction between vection and olfaction. We used two types of motion images with different directions and used two different scents, and measured the subjective strength by changing the strengths of these two stimuli. From the experimental results, we found that the subjective strength of the scent increased as the vection stimulus gets stronger. On the other hand, olfactory stimuli had some effect that makes vection perception irregular, but it was not clear from this experiment what kind of brain mechanism is the cause.

This paper examined the influence of passive whole-body motions such as heave or yaw motions by a motorized chair on inducing a sensation of walking for seated participants in virtual environments while viewing a VR scene through an HMD. We conducted a pilot study to evaluate the influence of passive whole-body motions on perception as if the participant were walking. Experimental results show that the perception of pseudo-walking was greatly affected by heave motions rather than yaw motions, but just with a limited range of amplitude of heave motions. Our results suggest that the passive whole-body motions in the gravitational axis allow a clear perception of pseudo-walking. In addition, we found a strong correlation between the scores of a walking sensation and a motion sickness.

It is important to measure biological information during VR content experience because user’s internal state such as arousal and valence can be estimated. Based on the user’s internal state, VR content can be changed interactively. The existing biological information measurement technology has a problem that the user load on the sensor is large. Also, noise due to body movement is a problem. In this paper, a biological information measurement device that can be mounted on a head mounted display (HMD) was developed. Because an HMD is attached strongly to the face, it is thought to be robust to body motion and the mounting load of the sensor can be ignored. The developed device can simply be mounted on an HMD. A pulse waveform can be acquired from the optical pulse wave sensor arranged on the nose side of the HMD, and the respiration waveform can be acquired from a thermopile arranged in the nostril area of the HMD. We conducted the experiment to verified that a pulse wave and the respiration can be measured with sufficient accuracy for a calculation of the tension and excitement of the user. As a result of the experiment, it was confirmed that the pulse wave can be measured with an error of less than 1% in nine out of 14 users and that the respiration can be measured with an error of 0.6% if user does not move. It was also confirmed that the change tendency of RRV can be measured with sufficient accuracy for arousal estimation. The respiration was measured with high accuracy regardless of the type of HMD used. We showed the possibility that arousal could be estimated using only HMD during the VR experience.

This paper proposes a novel method of enhancing the pseudo-haptic effect on the touch screen. In prior studies to invoke pseudo-haptics on the touch screen, there has been a problem stemming from the difference in position between the finger and the object. We added the virtual string on display which shows a connection between the finger and the object. The user studies showed that the presence of the virtual string was effective to invoke pseudo-haptics, and the setting of string breaks was key to enhance the effect of it.

The pseudo-haptic presentation device is a device that presents the force sense illusion in the front and rear directions by causing the linear actuator to perform asymmetric vibration with a biased duty ratio. The purpose of this paper is to increase the degree of freedom of directionality of pseudo-haptics. In this paper, we develop the device that fixed multiple actuators perpendicular to each other and make 2-dimensional the direction of pseudo-haptics by vibration synthesis. By synchronizing the frequencies and phases of the two asymmetric vibrations and clarifying the arrangement method of the actuators for synthesizing the vibrations, synthetic vibrations maintaining the direction were generated. In addition, since the haptic perception is adversely affected by the direction of vibration stimulation with respect to the skin, we have improved to a device using four actuators and conducted an 8-direction discrimination experiment to develop a device with a higher rate of correct responses.

In performing rehabilitation, it is effective to feel kinesthetic illusion. Therefore, we invented the ball-rotation system that evoked kinesthetic illusion by simultaneously presenting visual stimuli and tactile stimuli. In this thesis, we evaluated kinesthetic illusion caused by this system using the questionnaire and the electroencephalogram (EEG). As a result of the questionnaire, we confirmed that kinesthetic illusion was caused by this system. As a result of the EEG, we confirmed that this kinesthetic illusion was caused by coordinated activities of motor cortex and visual cortex.