3D registration between real and virtual human body is a significant issue in AR surgical navigation. However, the matching of markers on surface of the body has a problem of estimating positions inside the body, because human body is not rigid. This paper proposed inside-body registration, which matched pair-line adjacent to a target tissue. Pair-line matching method, which has a high freedom of measured positions and high robustness of measurement errors, is useful, because the method never requires the correspondence of measured points between real and virtual world. In the experiment using a phantom, great vein was used for pair-line and the position of a vessel bifurcation was estimated. The result of experiments showed high robustness of measurement errors in estimating positions. The result using patient data showed sufficient estimation accuracy with even small distance between two measured points for pair-line.

抄録全体を表示

[Objective] A distance-learning system for manual skills training in Endoscopic Paranasal Sinus Surgery has been developed and a remote teaching experiment using the system successfully conducted between Kanazawa Medical University (Ishikawa) and AIST (Ibaraki), 200 miles away. [Equipment] The system consists of trainee and trainer sites connected using commercial internet services. Both sites have the same equipment: surgical instruments, a precise nasal model, and four monitors. Monitors 1 and 2 show the trainee and trainer endoscope view, and 3 and 4 are front and side view virtual mirrors, called the HyperMirror (HM) interface, which show trainee and trainer images side-by-side and horizontally flipped. HM monitors enable the postures of the two surgeons conducting the same procedure to be compared. [Procedure] One expert surgeon at AIST remotely taught 11 medical students (5th grade) two surgical tasks. A 10-minute lesson on each task was repeated 3 times over two days. Trainees performed each task themselves before the remote teaching, just after each lesson, after all lessons, and two months later. [Results] Trainer's subjective scores of the trainees significantly improved after remote teaching and the acquired skills were retained two months later. Task completion time fell significantly for the easier task as remote training proceeded, but not for the more difficult task. Average and maximum force applied to the patient model increased as remote training proceeded. In the easier task, it had fallen significantly after two months. [Conclusion] Surgical skills can be remotely taught using this system. Force is a good skill measure, because it directly represents tissue damage and completion time seemed to decrease even when force increased.

抄録全体を表示

This paper describes the development of a gait rehabilitation system using a locomotion interface. The locomotion interface can move a user's feet while it keeps their bodies in the real world. In this study, a locomotion interface was designed for using a hospital. Some conditions were considered in prototype development. The prototype system was placed in a hospital. A half year experiment with 12 hemiplegic patients was conducted in the hospital. And the effectiveness of the system was confirmed.

抄録全体を表示

In this paper, we present a technique of high quality haptic display working with low update rate rigid body simulator. The proposal method uses two dynamics simulators. One is low update dynamics simulator to simulate dynamics of whole virtual world and the other is high update rate dynamics simulator to simulate dynamics of objects nearby a haptic pointer which user controls (neighbor objects). Additionally, we calculate a mobility matrix of neighbor objects to consider contact force adding to neighbor objects. We did a simulation and experiment to check the effectiveness of the proposal method.

抄録全体を表示

This paper describes the characteristics of haptic sensation that is evoked at the finger skin by a shear force presented using rotational contactors. The psychophysical experiment was performed to provide a design basis for a shear force distribution display with six rotating shafts. The tactile sensation scaling for a shaft contactor was performed regarding five contactor conditions and two directions of rotation. Approximately six to eight levels were discriminated in the given 100-to-1500rpm range at the very tip of an index finger. The sensitivity difference among stimulation sites on a fingertip was investigated; the result showed that the highest sensitivity was observed at the fingertip. The interference between two shear stimulations added by a pair of shafts with a 3-mm interval was measured to show the masking effect. The results demonstrated that the sensitivity decreased with the increase of the intensity level provided by an adjacent contactor. These results provide valuable information to optimize the design of the shear force distribution display.

抄録全体を表示

Vection is an illusory self-motion perception induced by a coherent motion in a wide visual field. Scientific study of vection began in 1973 (Brandt et al., 1973). From this study, every parameters of every stimulus attribute was considered to be effective or inefficient to induce vection. These effective stimulus parameters can be applied to VR contents. In this 10 years many brain imaging studies also have done in vection. Those studies were reviewed and evaluated in this article. Those physiological results should be converted into stimulus parameters for developers of VR contents. This conversion should be made by psychological studies. The further psychological studies are necessary to connect the physiological knowledge and VR contents.

抄録全体を表示

We propose a novel interface to display high-quality tactile information by achieving a very wide frequency bandwidth. The system is composed of one or two speakers. Users hold the speakers between their hands while the speakers vibrate air between the speakers and their palms. The user feels suction and pushing sensations on their palms from the air pressure. In this paper we introduce basic concept, show the result of hardware evaluation, and further show some results of sealing techniques and pressure feedback control to improve tactile feeling.

抄録全体を表示

In order to construct haptic display for grasping a soft object using FEM, it is effective for deformation and reaction force calculation to calculate the center of gravity and posture of a reference object. In this paper, we propose the novel calculation method for the center of gravity and posture of the object. The proposed method calculates the center of gravity and posture of the object using force displacement and an inverse matrix of a stiffness matrix calculated by using SVD. In simulations of grasping the soft object, we confirmed validity of the proposed method.

抄録全体を表示

This paper reports the detection threshold of human hairy skin with the use of a direct vibrotactile stimulus to the hair on human hairy skin. We designed an experimental method to quantify the psychological effect and developed a stimulation instrument to directly stimulate the hair. This vibrotactile stimulation was provided from the tip of tweezers which traveled horizontally or vertically against the human skin. The stimulation point was the approximate middle region of the hair on the middle finger and forearm. A psychological experiment was conducted based on the hypothesis that a frequency characteristic exists on hairy skin with direct stimulus to the hair. As a result, a significant difference depends on frequency was obtained with ANOVA. It was described that the vibrotactile stimulus was conducted to Pacinian by the body hair on the middle finger which has so small section area. This is conflicting finding concerning the size of the contactor which can conduct the stimulus into the lower layer of skin. However, this threshold curve and also the introspection reports of participants support this novel finding.

抄録全体を表示