Takuto Nakamura

Application of Hanger Reflex to wrist and waist

When a wire hanger is placed sideways on the head, and the temporal region is sandwiched by the hanger, the head rotates unexpectedly. This phenomenon has been named the “Hanger Reflex”. Although it is a simple method for producing pseudoforce sensation, the use of the wire hanger in this way has up until now been limited in posistion to the head. Here we report a new finding that when a wrist or waist is equipped with a device of a larger circumferance the arm or the body rotates involuntarily. This fact suggests that the Hanger Reflex principle might be applicable to parts of the body other than the head, leading to the possible compact whole-body force display. This paper documents the development and testing of the devices and, suggesting stable presentation of the rotational force.

JOLED: A Mid-air Display based on Electrostatic Rotation of Levitated Janus Objects

We present JOLED, a mid-air display for interactive physical visualization using Janus objects as physical voxels. The Janus objects have special surfaces that have two or more asymmetric physical properties at different areas. In JOLED, they are levitated in mid-air and controllably rotated to reveal their different physical properties. We made voxels by coating the hemispheres of expanded polystyrene beads with different materials, and applied a thin patch of titanium dioxide to induce electrostatic charge on them. Transparent indium tin oxide electrodes are used around the levitation volume to create a tailored electric field to control the orientation of the voxels. We propose a novel method to control the angular position of individual voxels in a grid using electrostatic rotation and their 3D position using acoustic levitation. We present a display in which voxels can be flipped independently, and two mid-air physical games with a voxel as the playable character that moves in 3D across other physical structures and rotates to reflect its status in the games. We demonstrate a voxel update speed of 37.8 ms/flip, which is video-rate.

Effect of Hanger Reflex on walking

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 first experiment, we confirmed that the Hanger Reflex at the waist significantly affects walking direction. In the second experiment combining Hanger Reflex devices at the head, waist, and ankle, we confirmed that the waist application is most effective, and that combined Hanger Reflex imparted limited influence on the results.

HangerOVER: HMD-embedded haptics display with hanger reflex

As a simple method to experience VR content with high immersion, we propose HangerOVER, an HMD-embedded haptics display that can provide both tactile and force senses using the Hanger Reflex (Figure 1). The Hanger Reflex is a phenomenon in which the head rotates unintentionally when appropriate pressure distribution is applied to the head. As it accompanies illusory external force and motion, it can be used to express haptics event in VR environment, such as being pushed and punched by a game character. The developed device is composed of air-driven balloons that can express four types of haptics senses such as touch, pressure, motion & force, and vibration. It can not only improve the immersion of the users VR experience, but also extends the degree of freedom of expression by game creators.

Perceptual Force on the Wrist Under the Hanger Reflex and Vibration

The hanger reflex is a phenomenon that accompanies illusory force sensation and involuntary head rotation when the head is fastened with a wire hanger. This phenomenon is also observed on the wrist, and is expected to apply when using small and simple haptic feedback devices. However, issues of slow response and the requirement for large actuators still remain. Here, we discuss the discovery of a new phenomenon: the perceptual force from the hanger reflex is enhanced when a vibration is also presented. If we can control the strength of the perceptual force induced by vibration, a smaller, simpler, and higher response device might be achieved, because a vibrator can be controlled easily. This paper reports details of this phenomenon, and the effect of the frequency and amplitude of the vibration on the strength of the perceptual force. We observed that low frequency 50---100i?źHz vibrations efficiently enhanced the perceptual force, and that participants perceived a stronger perceptual force if the vibration of a greater amplitude was presented. These results suggest that the enhancement of the perceptual force is controllable and can be applied to construct a new type of wearable haptic device.

Hanger Reflex of the Head and Waist with Translational and Rotational Force Perception

The hanger reflex is a phenomenon in which the head involuntarily rotates when force is applied via a wire hanger placed on the head. The application of pressure to particular points of the head is necessary to induce this phenomenon, which occurs when shear deformation of the skin induces illusory force perception. Because the hanger reflex represents the induction of force and motion using a simple device, and has been found in other body parts such as the wrist, waist, and ankle, it is expected to be useful as an application in haptic interface technology. In this paper, we describe new directions of force associated with the hanger reflex; four translation, and two rotational directions of the head, and four translation and one rotational direction of the waist.

Interpretation of navigation information modulates the effect of the waist-type Hanger Reflex on walking

The Hanger Reflex is a phenomenon in which the head rotates unintentionally when force is applied via a wire hanger placed on the head. This phenomenon is caused by physical pressure on the skin, and the direction of the Hanger Reflex modulated by the direction of skin deformation. A previous study examined the use of the head-, waist-, and ankle-type Hanger Reflex on walking navigation without interpretation of navigation information, and found that the waist-type Hanger Reflex had the strongest effect on walking. However, the existing waist-type Hanger Reflex device is passive; i.e. must be operated by the user, which leads to the necessity of developing a new active type device for use as part of a navigational system. In this paper, we developed a controlled waist-type Hanger Reflex device with four pneumatic actuators. We investigated different interpretations of navigation information on the effect of our device on walking. Our interpretation conditions included “Natural”, in which users did not attempt to interpret the navigation information, “Follow”, and “Resist”, in which they actively followed, or resisted the navigation information, respectively. We confirmed that our waist-type Hanger Reflex device could control the walking path and body direction, depending on users interpretation of the navigational information.

Wearable Haptic Device that Presents the Haptics Sensation Corresponding to Three Fingers on the Forearm

In this demonstration, as an attempt of a new haptic presentation method for objects in virtual reality (VR) environment, we show a device that presents the haptic sensation of the fingertip on the forearm, not on the fingertip. This device adopts a five-bar linkage mechanism and it is possible to present the strength, direction of force. Compared with a fingertip mounted type displays, it is possible to address the issues of their weight and size which hinder the free movement of fingers. We have confirmed that the experiences in the VR environment is improved compared with without haptics cues situation regardless of without presenting haptics information directly to the fingertip.

Development of a Wearable Haptic Device that Presents the Haptic Sensation Corresponding to Three Fingers on the Forearm

Numerous methods have been proposed for presenting tactile sensations from objects in virtual environments. In particular, wearable tactile displays for the fingers, such as fingertip-type and glove-type displays, have been intensely studied. However, the weight and size of these devices typically hinder the free movement of the fingers, especially in a multi-finger scenario. To cope with this issue, we have proposed a method of presenting the haptic sensation of the fingertip to the forearm, including the direction of force. In this study, we extended the method to three fingertips (thumb, index finger and middle finger) and three locations on the forearm using a five-bar linkage mechanism. We tested whether all of the tactile information presented by the device could be discriminated, and confirmed that the discrimination ability was about 90%. Then we conducted an experiment to present the grasping force in a virtual environment, confirming that the realism of the experience was improved by our device, compared with the conditions with no haptic or with vibration cues.

Haptopus: Transferring the Touch Sense of the Hand to the Face Using Suction Mechanism Embedded in HMD

Along with the spread of VR experiences by HMD, many proposals have been made to improve the experience by providing tactile information to the fingertip, but there are problems such as difficulty in attaching and detaching and hindering free movement of fingers. As a method to solve these issues, we developed Haptopus, which embeds the tactile display in the HMD and presents tactile sense associated with fingers to the face. In this paper, we conducted a preliminary investigation on the best suction pressure and compared with the conventional tactile presentation approaches. As a result, it was confirmed that Haptopus improves the quality of the VR experience.