This paper describes a new virtual manipulation environment with 6 DOF Cartesian manipulator for force feedback display. The manipulator is controlled by the force the operator puts on the lever, and it can present virtual surfaces of wide range of mechanical hardness, from very hard to very soft. With this system the operator can trace the smooth surface smoothly even under the control of several hundred cycle-time. We performed several experiments including virtual peg-in-hole experiments to verify the system's performance and effectiveness in constructing virtual environment applications.

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The importance of force and tactile display in virtual reality technology has been recognized recently and numerous researches have been done including development of various force and/or tactile display devices. However, many of them are always in touch with fingers or hands of operators and it is impossible for an operator to feel difference between contact and non-contact state with a virtual object directly from sensory channel of touch in his/her finger or hand. This paper presents a new haptic display device we have developed which provides both touch and force feeling to the operator's fingers.

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If shoes or slipper-like interfaces were developed, we could walk in virtual environments by walking in the real world and physical, and psychological discomforts caused by wearing special devices would be minimized. In order to transmit information from the system, tactile sensations by multiple vibrators on the soles were studied. Fundamental characteristics, especially phantom sensation, of human sole tactile sensations by multiple vibro-tactile stimulators were psychophysically measured, and stimulation conditions eliciting phantom sensation were elucidated. It was found that the location, movement and rotation of objects are perceived through the sole, and this concept can be implemented in shoesoles.

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As a basis for tactile display, it is important to understand the mechanism of tactile sensation. So, we analyze elastic waves inside a finger in tactile exploration with a two-layered, half-infinite elastic finger model, and derive a mapping from objects shapes to mechanoreceptors displacements. It is shown that this mapping is a one-to-one mapping. Therefore, it is necessary to create the same finger surface displacement as in actual exploration for tactile virtual reality(VR). However, the mapping from objects shapes to finger surface displacements is shown to be a many-to-one mapping because of the mechanical property of skin. So, we use the envelope of the amplitude-modulated Lamb wave on an elastic plate as an alternative shape to the real object, because its shape is easily controlled. The generation of the wave is confirmed with an experimental device of silicon rubber vibrated by voice coils.

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Haptic display is a very powerful tool for CAD/CAM system. It enables the users to define and modify the shape of models intuitively and directly. In a CAD/CAM system, shape is expressed by a surface model or a solid model. Nowadays, NURBS surface has been commonly adopted as expression of shape in a CAD/CAM system, because it can express typical model such as Bezeir, B-spline, or conic. It has unstableness for calculation and heavy calculating load, because of NURBS has rational expressions. The purpose of this research is to find how to display NURBS surfaces stably by haptic sensation. For that purpose, this paper treats the interference between a NURBS surface and a point. The stable algorithm for NURBS is described and implemented in the experimental system. Finally, the accuracy of the displayed surface with the experimental system is described.

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In virtual reality systems, which can be operated with a hand, it is necessary to provide not only visual infomation but also haptic infomation. In most conventional virtual reality systems, however, visual infomation and haptic infomation are displayed separately, which makes it difficult for humans to feel they are the same object. It is desirable if we can touch where we can see. In order to accomplish such systems, it is important to realize how humans perceive real objects. In this paper, human perceptional characteristic when visual infomation and haptic infomation are displayed simultaneously, is studied, particularly on the perception of a rotational angle of a line on a certain plane. It is found that the angle differnce between a displayed visual line and a displayed haptic line exists in order to fuse the visual and haptic sensation, and it is dependent on a rotaional angle of the displayed line. It is also revealed that the proprioception is surperior to the cutaneous sensation, and that the characteristics by a right hand and that by a left hand are similar.

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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.

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We propose an operational assistance system of a rough terrain crane. The system can change strength of assistance adapting to the operator's skill level. We propose a proper control rule to suppress the payload's swing. Stability of the proposed rule is confirmed by Lyapunov stability criterion. Based on this rule, we propose an operational assistance method using a haptic device. We perform some experiments on a VR crane simulator and show the effectiveness of the proposed system.

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To carry out contact work naturally in virtual space, it is important to present somatosensory information by haptic display. Some haptic display systems have been already proposed and existed, but these systems are designed not considering the characteristics of human sense perception. So, in this study, we quantified the JND( just noticeable difference) of human spatial perception attended with touch sense and gave the necessary and sufficient accuracy for designing haptic display systems. First of all, we focused on a simple haptic task and carried out psychophysical experiments to quantify the JND.

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Force display systems are very important devices in many fields such as virtual reality, rehabilitation, amusement or etc. A force display system is a kind of robot system which presents a force sense to human being. Since the operator must grip the tip of the robot system directly, the maneuverability and kinetic safety of the system become very important. Many force display systems or haptic interfaces have been developed which used servo motors for their actuators. But, the conventional servo motor does not always suit for the force display system. We developed a new actuator using ER fluid. The ER actuator has the characteristics which suit for the force display system. Then, we developed a 2 D.O.F. force display system using ER actuators. This system can provide good force senses in various situations.

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This paper describes a method of synthesizing haptic sensation to the whole human body using vibrators in large working volume virtual environment. In such environment, haptic devices must have following characteristics, (1) large working volume (2) light weight (3) easy to move. Vibrating device is satisfied such characteristics. By setting some vibrators to user's body and controlling the pattern of the vibration, we can feel the virtual object. We developed a vibrator suit in CABIN(Computer Augmented Booth for Image Navigation). Using this system, we can feel virtual objects and walls through the whole body and walk virtual world to avoid interfering these walls. The effectiveness of this system is tested through experiment.

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We discuss the way how to locate and manipulate the multi-viewpoint data set (MVDS) in virtual environment. Since MVDS has no geometric information within it, additional information, which links a virtual object represented by MVDS and a virtual space based on its geometry, should be attached to it. Without having that kind of information, no manipulation in virtual space is possible. In this paper, several types of link information are studied from the point of interactivity. In addition, experimental examples confirm the usefulness of MVDS with the link information.

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In order to establish immersive virtual environments, efficient rendering of photorealistic scenes is crucial. To this end, texture mapping is commonly used to play a complementary role with 3D geometric modeling and rendering. In previous reports, we have proposed an adaptive texture mapping strategy based on a human-behavior model (HBM) for effective interior space simulation. This paper extends the approach to another attractive VR application, that is, virtual museums. A new specific HBM estimates in which mode the user acts at present, searching or admiring particular pictures, based on the dynamics of his/her position and gaze for static exhibition scenes mixed with moving objects such as audience. Also, an improved adaptive strategy fully takes into account the nature of a texture mapping hardware to select for each mode the best level of detail (LOD) of object textures in the current field of view. An empirical test is performed to evaluate to what degree the present HBM and adaptive LOD control strategy resolve the trade-off between efficiency and image quality, and provide the user with the immersiveness for museum navigation.

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This paper describes a generalized data structure for virtual tools used in virtual world with a hand. The proposed model contains the knowledge, such as the shape of the tool, how to use the tool with a hand, and how to manipulate objects by the tool. Introducing this kind of data structure, we can separate the models for virtual tools from virtual manipulation system itself, so that any type of tools is introduced in a very simple manner.

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It is said that the visual information is very important for human. A lot of efforts have been paid for visual system of virtual reality technology. But the other sensory information is also important for the quality of reality. In this paper, the importance of visual information, in particular, the peripheral visual information is discussed. And a combined effect of visual and auditory information on the sense of equilibrium is discussed. The combined effect is that a static auditory stimulation decreases the effect of peripheral optical flow on human posture. The usefulness of the combination of visual and auditory information on virtual reality technology is confirmed. Finally, the wide-view vision display systems and 3D auditory display systems arc recommended to realize the true and comfortable virtual reality systems.

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Augmented Reality (AR) has been received with much attention for a new interface between humans and computers. In this paper, we describe a new supporting environment for inspection work of electronic parts by involving AR technology. As AR aims to augment the real world, this paper treats a concrete inspection work with real electronic boards by superimposing visual markers, visual commands and virtual instruments. An inspection management system with visual target tracking subsystem with two sided cameras, AR manual and the virtual instruments can reduce work time and the number of mistakes. Results showed that ten subjects who used this environment did a typical inspection faster with less number of mistakes than other ten subjects who used a paper manual did.

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