Yukio Fukui

Human shape recognition performance for 3D tactile display

The paper describes the relationship between the pin-matrix density of a tactile display and the recognition performance of displayed 3D shapes. Three types of pin-matrix tactile display, that generate 3D shapes, were used for the experiment. The pitch of pins was 2 mm, 3 mm, 5 mm each. We assumed that surfaces, edges, and vertices were primitive 3D shape information, so tested shapes were classified into these three categories. We assumed two types of finger touching mode: 1) fingertip-only, allowed full use of spatial shape information given to the fingertip; and 2) allowed tracing of the object. Recognition time and the classified error rate were measured. We obtained results on the relationship between pin pitch and recognition performance data. Regression curves for pin pitch and recognition time were plotted. A significance test of recognition time versus pin pitch was done. The error rate of identification versus pin pitch was described. Our results provide basic knowledge for developing tactile presentation devices.

Characteristics of accommodation toward apparent depth.

This paper deals with characteristics of accommodation evoked by perceived depth sensation and the dynamic relationship between accommodation and vergence, applying newly developed optical measurement apparatuses. A total of five subjects looked at three different two-dimensional stimuli and two different three-dimensional stimuli; namely a real image and a stereoscopic image. With regard to the two-dimensional stimuli, a manifest accommodation without any accompanying vergence was found because of an apparent depth sensation even though the target distance was kept constant. With regard to the three-dimensional stimuli, larger accommodation and clear vergence were evoked because of binocular parallax and a stronger depth sensation. As for the stereoscopic image, a manifest overshoot (the accommodation peaked first and receded considerably) was found while the vergence remained constant. On the other hand, the overshoot of accommodation was smaller when subjects were watching the real image. These results reveal that brain depth perception has a higher effect on accommodation than expected. The relationship of accommodation and vergence toward the stereoscopic image suggests a reason why severe visual fatigue is commonly experienced by many viewers using stereoscopic displays. It has also paved the way for the numerical analysis of the oculomotor triad system.

Development of a force and torque hybrid display "GyroCubeStick"

Multimodal interfaces with the five senses attract a great deal of attention as for the next generation multimedia interface. Especially, the interfaces with additional tactile sensation and force feedback enable us to perform pointing and manipulation operations and navigation operations easily rather than the conventional interfaces without them. The display device using pin array and manipulation arms is the most popular to display tactile sensation and force feedback. The arms and wires restrict users movement and reachable area around the device base connected to the arms. These devices are relative larger and are not convenient for mobile uses. Therefore, in this paper, a torque and force feedback device of non-grounding and no reaction base on the human body has been developed, which displays the torque of virtual objects and normal and tangential force on the surfaces as the resistance force and tactile sensation.

Surgical Skill Evaluation by Force Data for Endoscopic Sinus Surgery Training System

In most surgical training systems, task completion time and error ratio are common metrics of surgical skill. To avoid applying unnecessary and injurious force to the tissue, surgeons must know for themselves how much force they are exerting as they handle surgical tools. Our goal is to develop an endoscopic sinus surgery (ESS) training system that quantitatively evaluates the trainees surgical skills. In this paper, we present an ESS training system with force sensors for surgical skill evaluation. Our experiment revealed that the integral of the force data can also be one of the useful metrics of surgical skill.

Dynamic eye accommodation evoked by apparent distances

A three-dimensional optometer (TDO), which can measure simultaneously three major ocular functions in a working environment, was used to measure the visual responses of human subjects viewing: (1) actual artworks and (2) corrugation presented by moving random dots on a cathode ray tube (CRT). Measurements were performed in natural viewing conditions on two emmetropic females. Both subjects demonstrated distinct accommodative responses for the stimuli presented at a fixed distance. The results indicate that the accommodation generally shifts in accord with changes of perceived distance. The usefulness of the TDO was demonstrated in these experiments.

Three-dimensional optometer.

This paper describes the optical and control principles of a newly developed three-dimensional optometer (TDO). The TDO makes it possible to measure simultaneously three basic ocular responses in an actual work situation: accommodation; eye movement; and pupil area. Although the subjects must use a chin rest, they need not fixate their eyes or use any drug for the measurement. Normal lighting is allowed. The TDO can measure accommodation from -12.7 to + 26.6 diopters and 100% of pupil area change when the eye moves within 40 degrees horizontally and 30 degrees vertically. The accuracy of measuring both accommodation and pupil area with the TDO is about the same as that of commerically available apparatus: +/-0.25 diopters and +/-2%, respectively. The error of measuring the angle of the eyes was less than +/-0.5 degrees . Examples of measurements during work with a visual display terminal are presented.

Development of Fingertip Type Non-grounding Force Feedback Display

Force feedback displays to represent virtual objects with non-grounding and no reaction base on the human body are convenient and effective for mobile uses. Especially, these sensations are expected to be applied to ubiquitous/mobile/wearable interfaces for technical training, rehabilitation and telemanipulation in the variety fields of medical care, healthcare, and welfare. In this paper, fingertip type non-grounding force feedback display has been developed to represent the feeling of presence and shape of virtual objects continuously by downsizing to be mounted to fingertip and position feedback controlling. This display represents haptic sensation of vibration, torque, and force feedback in any arbitrary direction by controlling rotor acceleration and phase difference of eccentrically weighted rotators

An interactive design system for pop-up cards with a physical simulation

We present an interactive system that allows users to design original pop-up cards. A pop-up card is an interesting form of papercraft consisting of folded paper that forms a three-dimensional structure when opened. However, it is very difficult for the average person to design pop-up cards from scratch because it is necessary to understand the mechanism and determine the positions of objects so that pop-up parts do not collide with each other or protrude from the card. In the proposed system, the user interactively sets and edits primitives that are predefined in the system. The system simulates folding and opening of the pop-up card using a mass–spring model that can simply simulate the physical movement of the card. This simulation detects collisions and protrusions and illustrates the movement of the pop-up card. The results of the present study reveal that the user can design a wide range of pop-up cards using the proposed system.

Shape identification performance and pin-matrix density in a 3 dimensional tactile display

Tactile display devices use an array of pins mounted in the form of a matrix to present three-dimensional shapes to the user by raising and lowering the pins. With a denser matrix of mounted pins, it can be expected that shape identification will become easier and the time required for identification will also become shorter, but that problems of difficulty in fabrication will arise. It is necessary to consider such trade-offs in the development of such devices. The authors conducted experiments to study the effect of pin pitch on shape identification as part of the fundamental investigation of this subject. The experiment used three tactile display devices with pin pitches of 2 mm, 3 mm and 5 mm for geometrical shape identification, with response time and rate of misidentification taken as the performance data. Surfaces, edges and vertices of three-dimensional shapes were used as the shape primitives for displayed shapes and several of each type were selected for presentation. The results obtained revealed that performance has different relationships to pin pitch with different shape primitives.

Generating autonomous time-varying virtual cities

We propose an approach to generating virtual cities that vary dynamically over time, focusing on the layout of artificial elements such as building, roads, and traffic lights. We first define an environment vector as the amount of features reflecting economic and functional activities of citys residents in each block surrounded by roads. Our method generates virtual cities by deleting and locating buildings from two points of view: building layouts using environment vectors, which can represent features, themselves to generate cityscapes, and time-varying using changes of vectors to vary cityscapes. We introduce three modules of our city model briefly, and describe how our system relocates buildings in each block. In addition, we demonstrate that our method can represent features and generate various cityscapes that vary over time.