Several kinds of vibration actuators were developed and widely used for haptic feedback and for simulating tactile experience. However, these actuators have certain design challenges, such as resonance via the spring attached to the vibration mass, and limited acceleration amplitude at low frequency because of the limited travel distance of the mass. In our study, we propose a new vibrotactile presentation method using the rotational motor's counterforce that occurs during acceleration or deceleration. This paper describes the effectiveness of a DC motor for high fidelity vibration and pseudo force presentation, and our design concept of a vibration actuator using a DC motor.
Application of the Hanger Reflex to walking navigation was investigated. The Hanger Reflex is a phenomenon that produces an illusory force and involuntary rotation of the body parts by skin deformation. It was first applied at the head by using a wire hanger, but is now known to work on many body parts such as the waist, wrist, and ankle. In the experiment combining Hanger Reflex devices at the head, waist, and ankle, we confirmed that the waist-type Hanger Reflex is the most effective, and that combined Hanger Reflex imparted limited influence on the results.
We propose a novel method to present virtual food texture by using electrical muscle stimulation (EMS) to the muscles of mastication. The system consists of “bite detection module”, “food texture database”, and “electric stimuli module”. A photoreflector is used to measure motion of the user's lower jaw for “bite detection”, electromyography sensors are used to measure food texture for “food texture database”, and a medical electrical stimulator is used for “electric stimuli”. We describe some preliminary studies to verify the feasibility of the proposed method. The results suggest that the photoreflector can detect bites, peak amplitude and pulse width of EMG are useful to represent food texture, and users feel hardness and elasticity of virtual food texture by presenting EMS to the masseter muscle.
Wearable devices have been numerously reported so far which aim to augment eating experience by applying crossmodal perception that multiple senses are interacting with each other and are integrated as one experience. As for devices which append sensory stimuli artificially, it is considered that multisensory integration would be lost if a delay between multiple sensory stimuli arises. On the other hand, a novel experience could be also obtained by utilizing the delay. This research investigated the perception of a time-lag between delayed auditory feedback of chewing potatochips and actual chewing behavior. As a result, most of the participants perceived time-lags at more than 200 [ms], and this result can be attributed to the durations of closing and occlusal phase of mastication. This research also investigated the effect of the time-lag on “zakuzaku” (crunchy) feeling of potatochips. As a result, 100 [ms] time-lag augments zakuzaku feeling most, and the evaluation values of zakuzaku feeling tend to vary more widely when the time-lag becomes perceived. According to the above results, this paper showed that delayed auditory feedback of mastication could augment zakuzaku feeling without spoiling multisensory integration.
In this study, the authors examined behavioral characteristics during viewing 360-degree (360) images by measuring time-series change of body part rotations. In the experiment, two conditions were prepared. First was the HMD condition which a simple head-mounted display using a smartphone was used, and second was the LCD condition which a LC display with similar viewing angle was used. Four types of still images with different number of gaze targets were presented as the experimental stimuli. Under the two experimental conditions, body part rotations of the participants and subjective indexes on motion sickness and visual fatigue were measured and analyzed. From the results of the experiment, the authors found a common tendency of the late and peak in the time series rotation of body parts. The authors discussed further results of the experiment in terms of the basic tendencies of behavioral changes by viewing 360 images.
We propose a method of estimating head posture with one depth sensor dangled from neck. The sensor located in front of chest measures point cloud of a lower chin, and then a center of gravity extracted from the measured point cloud. To obtain certain relationship between the center of gravity and head posture, we compare the center of gravity and a magnetic sensor with using regression analysis. Also we conducted user study to unveil accuracy of the method of estimating head posture. As a result, using regression analysis between center of gravity position of the chin and head posture, a head posture can be estimated with an accuracy of 5 degrees.
Galvanic Sight Stimulation (GSS), of which electrodes are attached on the head skin near the eyes, induces white flash sensation. This visual sensation is named phosphene. Since GSS can induce visual sensation with light weight, reasonable, and small electrical circuit and electrodes only, this technology is an attractive replacement of Head Mounted Display (HMD). To use GSS as HMD, it is required to control the position, strength, shape, and color of the visual sensation induced by GSS. In this work, as the initial stage of the entire study, we demonstrate that the multi-electrode GSS, which we newly invented shifts the position of the phosphene.
This paper reports on the effect of the physical state of the body on touch sensations caused by collisions with virtual objects. The collision of a virtual object with a user's body in a virtual environment may cause an illusory touch, or haptic, sensation. We hypothesize that a real-world touch sensation of moving air on skin may augment an illusory touch sensation created by the visual representation of a collision with an object in a virtual scene. To assess this hypothesis, we performed experiments evaluating touch sensation in three conditions: with the user's body covered, with the user's body uncovered, and when blowing air onto the user. Our results showed that a touch sensation was strongly induced in the condition where the user's body was uncovered. Furthermore, the effect of blowing air onto the user differed depending on the body part that was stimulated and the representation of the virtual object. These results suggest that the top-down and bottom-up information for illusory touch sensation such as the user's physical state and the touch sensation of the air on skin had affected each other.
The representation of the peripersonal space is remapped by body action such as integrating tactile stimuli from the body's surface with multisensory stimuli presented within a limited distance from the body. Previous study showed that boundaries of the peipersonal space extend while walking with listening to a looming sound, but it is unclear whether the boundaries change when a sensation of walking is induced with no physical body motion. Here, we examine the change using a technique to induce a sensation of pseudo-walking by presenting vibrotactile stimuli of recorded footsteps sound at the feet soles. Experiments were performed to compare the reaction times to detect a vibrotactile stimulus on the chest with listening to a looming sound toward the body, taken as a proxy of the peripersonal space boundary. Experimental evaluations showed that the peripersonal space seems to expand when a sensation of pseudo-walking was clearly induced.
In Mixed-Reality space, it appeared that the sense of weight can be affected by a MR visual stimulation with a movable portion. We named this psychophysical influence caused by the difference between dynamics of the real object (R) and the virtual object (V) movement, the “R-V Dynamics Illusion”. There are many combinations of experiments that can be conducted. Previously, we conducted experiments of the case where the real object is rigid and the virtual object is dynamically changeable. In this paper, we conducted experiments of the case where the real object is liquid and both the real and the virtual objects are dynamically changeable. The results of the experiments showed that the subjects sensed weight differently when virtual object with a movable portion is superimposed onto a real liquid object.
There are numerous proposals of tactile displays that aim to improve music listening experiences. However, these devices commonly have problems, such as the heavy weight and large size of the device due to numerous actuators, which lead to long setup time and user confinement to the system. To address these issues, we proposed to present vibration via user's collarbone. In this paper, we first investigated whether presenting vibration to the collarbone really contributes vibration transmission to wider areas of a user's body. Then, we performed a psychophysical experiment to evaluate subjective vibration effect with actual music listening experience. Results suggest that presenting vibration through the collarbone induces vibration transmission to wider area, and contributes user's subjective music listening experience.
In this research, the effects on preference and visual characteristics were examined on correlations with changing parallax angle conditions in stereoscopic 3D images. Specifically, we investigated the influence of their preference decisions in 2D and 3D conditions as well as the different type of parallax angle including the negative and positive parallaxes. In experiment 1, six novel shapes excluding humans' experience were presented with five types of parallax angles (-0.5, -0.2, 0, 0.2, 0.5 degree). The experiment of paired comparison which selected one from two shapes was conducted and eye movement was measured. As a result, the negative parallax type was preferable to the positive angle, which was influenced by the absolute value of the parallax angles. In experiment 2, the time and numbers of eye fixation were measured by eye movement analysis under the same stimuli and apparatus when performing paired comparison tasks with two types of parallax angles (-0.5 and 0.5 degree). The result was that the time and numbers of eye fixation more increased during viewing negative parallax conditions than positive one.
In augmented reality (AR) applications, a marker is often used for its robustness for camera pose estimation and its easiness for placing virtual objects on user's desired positions. However, AR markers in video may prevent from seamlessly fusing real environments and virtual objects. Therefore, plausibly hiding AR markers is desired in AR applications. As technology that can be applied to marker hiding, diminished reality (DR) has been investigated to visually remove real objects from video in real-time by generating plausible background images on them. However, conventional DR methods cannot correctly reproduce background images with highlights on a specular surface. This paper proposes a method that plausibly removes AR markers on a specular surface by estimating an illumination environment from images and reproducing highlights on a background image according to camera poses. Experiments show the effectiveness of the proposed method by placing an AR marker on various environments and comparing results obtained by the proposed and conventional methods.
In this study, the effects on concentration of attention, cognitive activity such as memory was examined in consideration of humans' cognitive characteristic over 3D images about the partial 3D image which changed a part of picture. The experiment of concentration of attention was carried out by measuring reaction time in visual search task using a simple visual target and eye fixation while viewing natural color image. On the other hand, the experiment of cognitive effect such as memory, the searching time until the changes are recognized were computed using the change blindness subject. That needs the cognitive activity of comparing by memorizing a picture temporarily while turning a look for detection of change. As a result, it was suggested by the partial 3D image that an object has the cognitive effect which is easy to go up to consciousness and to remain in memory.