Hiroo Iwata

This paper describes about spherical immersive display using convex mirror. Our display provides seamless image that totally surrounds a viewer. In order to construct the system, we designed optical configuration of display through the virtual projector that simulates behavior of projected light. The prototype display based on the optical design provides 360 degree horizontal and 115 degree vertical image. This optical configuration has an advantage in displaying video image. Then we also developed a camera head with convex mirror, which corrects distortion of displayed image.

Micro surgery needs adequate navigation by using virtual reality technology. This paper proposes method of haptic representation of non-invasive area fo r support system of micro surgery. An operator of our system holds 6 DOF force display and sees volume graphics. In case the virtual treatment tool approaches non-invasive area, force is applied to the operator's hand in order not to invade the area. Generated force is determined by volume data of CT image. Through the evaluation of the basic performance of this method, we applied our algorithm to experiment of navigation in human gullet.

Haptic feedback plays an important role to recognize and manipulate objects in virtual environments. Recently, high quality haptic feedback devices have been commercially available. However, the basic software for haptic devices is not prepared sufficiently. In this paper, we propose Haptic Interface Platform(HIP) that is a common software library independent of the types of haptic devices to construct virtual environments with haptic feedback. HIP supports three types of haptic device types:Point Type, Surface Type and Texture Type. To generalize Haptic Interface Platform, we classified it into three functions: (1)device driver, (2)haptic Tenderer, (3)haptic simulation engines. HIP enables users to make complex virtual environments easily. Since HIP is compatible with many haptic displays, we will also be able to accumulate haptic software assets and reproduct software in making applications. In the last of this paper, we developed simple haptic models using HIP and experimented how humans would feel them for each haptic display. We verified that HIP made the similar sensation for each display.

This paper describes about design and evaluation of wearable force display. We developed a 3 DOF joystick that is mounted on a user's arm. The device is mobile and easy to put on. Force is applied between arm and fingertip. Fingertip is much sensitive than arm so that the user can feel virtual wall at the finger. Performance of the device is tested by manipulation of virtual buttons and tracing task of virtual walls.

This paper describes about design and evaluation of wearable force display. We developed a 3DOF joystick that is mounted on a user's arm. The device is mobile and easy to put on. Force is applied between arm and fingertip. Fingertip is much sensitive than arm so that the user can feel virtual wall at virtual walls.

This paper describes about visual and haptic representation of multidimensional data. Recently visualization is a powerful tool for investigation of scientific data. These data often contain high dimensional parameter which makes difficulty in visual representation. We therefor had proposed haptization that gives haptic sensation to the multidimensional data and had examined it with model data. In this paper, we introduced haptization into representation of CT data of human head for evaluation of haptic feedback. We extended the method of haptization to four-dimensional space. Our 4-D cube is generated by scanning a 3-D cube. Users of our system can easily recognize distribution of volume data in 4-D space. The usability of our 4-D browser is examined through recognition performance tests.

This paper presents design method of rear-projection based dome screen. Spherical screen is ideal for spacial immersive display, because distance between the viewer and the screen is constant. Spacial immersive display must use rear-projection screen. If the screen is front-projection, the viewer obstruct the projected image. This paper discusses issues in design of rear-projection dome screen such as choice of projectors, determination of radius of the screen, and distortion correction.

This paper presents design method of rear-projection based dome screen. Spherical screen is ideal for spacial immersive display, because distance between the viewer and the screen is constant. Spacial immersive display must use rear-projection screen. If the screen is front-projection, the viewer obstruct the projected image. This paper discusses issues in design of rear-projection dome screen such as choice of projectors, determination of radius of the screen, and distortion correction.

Force feedback plays an important roll in recognition and manipulation of virtual objects. Recently haptic devices such as PHANToM and HapticMaster are manufactured. In accordance with rapidly growing network technologies, we can easily get electric media resources rpicture and movie and VRML and various digital sound data and so on. However, those electric media resources can only be seen and heard. We can't touch them because there is no software to integrate haptic devices and those electric media resources. In this research , we developed a system that enables users to easy construction of virtual environment with force feedback.We propose that the software for haptic device should have following characteristics. (1) haptic models and haptic rendering function. (2) managing engine of virtual object's behavior. (3) user interaction methods. We implemented the software called Virtual Environment Construction System(VECS).By using this system, we developed 3D shape modeling environment.Through userability study by a large numbers of subjects, effectiveness of the haptic environment is examined.

Force feedback plays an important roll in manipulation in virtual environment. We have developed a software tool for programmers of haptic virtual environment called VECS (Virtual Environment Construction System). Required update rate of force feedback is much higher than that of visual feedback. VECS enables high update rate of force display in complex virtual environment. VECS has network interface by which multiple force displays are connected each other. In SIGGRAPH '95 we connected two force displays by Internet : One is located in Los Angels and the other is in Tsukuba. We also developed a WWW client called "Haptic Web." VECS supports VRML format. Users can feel rigidity or weight of virtual objects stored in a WWW server.

A basic simulation system for laparoscopic surgery was constructed. The system consists of force display in a virtual environment construction system. Recently, laparoscopic surgery has become popular around the world. However, this operation strategy requires very high dexterity, so that only some medical doctors can use it. Doctors can see the human organs in a three-dimensional environment in the case of ordinary operations. On the other hand, in the case of laparoscopic surgery, doctors can only see a narrow space in a two-dimensional environment on a CRT monitor and tactile information is decreased during operation procedures. We therefore developed a basic technology of surgical simulator for laparoscopic surgery. The focus of our research is the presentation of resistance from virtual organs. © 1997 The authors.

Higher dimensional space enhances intellectual activity of human beings. 3D graphics contains much more information than 2D graphics. We proposed visual and haptic representation of five-dimensional space. Our 5D space is generated by scanning 3D cube. The user's hand can essentially move in 3D space. We therefor use rotational motion of the hand for scanning 3D cube in 5D cube. The 3D cube is cutting volume of the 5D cube. The cutting volume moves by rotational motion around roll and pitch axis of the user's hand. Force display presents potential field which indicates axis of rotation. The user can easily separate rotational motion from translational motion by force feedback. Usability of the 5D cube is examined through recognition performance tests and we applied the 5D cube to CT data of human brain.

Higher dimensional space enhances intellectual activity of human beings 3D graphics contains much more information than 2D graphics. We proposed visual and haptic representation of five-dimensional space. Our 5D space is generated by scanning 3D cube. The user's hand can essentially move in 3D space. We therefor use rotational motion of the hand for scanning 3D cube in 5D cube. The 3D cube is cutting volume of the 5D cube. The cutting volume moves by rotational motion around roll and pitch axis of the user's hand. Force display presents potential field which indicates axis of rotation. The user can easily separate rotational motion from translational motion by force feedback. Usability of the 5D cube is examined through recognition performance tests.

Higher dimensional space enhances intellectual activity of human beings. 3D graphics contains much more information than 2D graphics. We proposed visual and haptic representation of five-dimensional space. Our 5D space is generated by scanning 3D cube. The user's hand can essentially move in 3D space. We therefor use rotational motion of the hand for scanning 3D cube in 5D cube. The 3D cube is cutting volume of the 5D cube. The cutting volume moves by rotational motion around roll and pitch axis of the user's hand. Force display presents potential field which indicates axis of rotation. The user can easily separate rotational motion from translational motion by force feedback. Usability of the 5D cube is examined through recognition performance tests.

ネットワークを用いて遠隔地と仮想環境を共有する際, 情報伝達に時間遅れが生じる. 相手の手を取って操作方法等を教えようとする教示作業では, 時間遅れの影響が深刻となる. 本研究では, 時間遅れのある環境で教示作業を行う場合の反力呈示手法を提案し, 評価実験を通してこの手法が有効に作用していることを示す.

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This paper describes a new method of representation of volume data with haptic sensation. Recently the volume visualization is often used for analyzing a large number of data. However volume visualized image uses color or intensity of pixel, thus it is hard to display high dimensional volume data. We proposed to give force feed-back to volume model in several way. And then we constructed presenting tool for volume data from computational fluid dynamics research.

When two users work in virtual space, they will be able to do more creative work if they can manipulate same object simultaneously. Most of virtual reality system however, have no force feedback mechanism. Unless force is fed back, special efforts are required to manipulate same object simultaneously. In this research, we developed a system that enable two users to work simultaneously in virtual environment with force feedback. The system provides force to bind two user's hand. This function assists teaching task in common virtual environment. Through experiment to defom virtual object with force feedback, effectiveness of force feedback in cooperative work is tested.

When two users work in virtual space, they will be able to do more creative work if they can manipulate same object simultaneously. Most of virtual reality system however, have no force feedback mechanism. Unless force is fed back, special efforts are required to manipulate same object simultaneously. In this research, we developed a system that enable two users to work simultaneously in virtual environment with force feedback. The system provides force to bind two user's hand. This function assists teaching task in common virtual environment. Through experiment to deform virtual object with force feedback, effectiveness of force feedback in cooperative work is tested.

Force feedback in virtual environment is the major research objective of Iwata Lab. in the University of Tsukuba. Virtual reality is based on active human behavior, which is distinct from other information media. Operation by human hand in virtual environment requires force feedback from virtual objects. Force feedback is only realized by physical interaction with the outer world. Construction of force feedback device contains hard problems and research of this area is at an early stage. Our laboratory has been dealing with development of mechanical configuration of force feedback devices and its applications. This paper introduces following three current results: (1) Pen -based force display, (2) volume haptization, and (3) artificial life in haptic virtual environment.

Force feedback in virtual environment is the major research objective of Iwata Lab. in the University of Tsukuba. Virtual reality is based on active human behavior, which is distinct from other information media. Operation by human hand in virtual environment requires force feedback from virtual objects. Force feedback is only realized by physical interaction with the outer world. Construction of force feedback device contains hard problems and research of this area is at an early stage. Our laboratory has been dealing with development of mechanical configuration of force feedback devices and its applications. This paper introduces following three current results: (1)Pen-based force display, (2)volume haptization, and (3)artificial life in haptic virtual environment.

When we work in virtual space, we need input device for measuring spatial motion of a human hand. In this research, we use force display for input device which generates reaction force from virtual object. We developed an operation system of virtual space. The system supports easy construct of virtual environment. Using this system, we developed a program that enables two users to work simultaneously in the same virtual environment. Through experiments of deformation of virtual objects, effectiveness of cooperative work in virtual space is tested.

In proportion to the generalization of robots, tutorial on robotics plays an important role in university. This paper presents a basic system of instruction for robotics and manipulator. The system is intended to be applied to a students lab. The authors have selected a compact three-joint manipulator for a tutorial program. The manipulator is designed to be an entry machine for robotics research, which enables easy handling and real-time calculation of kinematics.<BR>The tutorial program has three levels. Level 1 is a tutorial on basic servo system. In this course, the student is instructed in the step and frequency response characteristics. Study on nonlinearity is included in the course. Level 2 introduces the student to dynamic control. The emphasis of this course is on the effect of compensation for gravitational and inertial forces. Level 3 introduces the student to an application of the manipulator to a workspace. In this course, the student is instructed in PTP operation and trajectory planning.<BR>Performance of the system is evaluated by junior year students in University of Tsukuba. Through the experiments, the thought process of the students is investigated by protocol analysis.