オクトツリーに基づいた空間的情報の入力法と利用法

"A Feasible Approach to Automatic Planning of Collision-free Robot Motions" R. Bolles and B. Roth (Eds.), Robotics Research: The Fourth International Symposium, © 1988 MIT, Cambridge, MA: The MIT Press, (pp. 479-488)

Convergence Stability of Depth-Depth-Matching-Based Steepest Descent Method in Simulated Liver Surgery

We recently established that our digital potential function was globally stable at the point where a virtual liver coincided with its real counterpart. In particular, because three rotational degrees of freedom are frequently used in a surgical operation on a real liver, stability of the potential function concerning three rotational degrees of freedom was carefully verified in the laboratory, using fluorescent lamps and sunlight. We achieved the same stability for several simulated liver operations using a 3D printed viscoelastic liver in a surgical operating room equipped with two light-emitting diode shadowless lamps. As a result, with increasing number of lamps, stability of our depth-depth matching in the steepest descendent algorithm improved because the lamps did not emit an infrared spectrum such as the one emitted by our depth camera. Furthermore, the slower the angular velocity in a surgical sequence, the more overall stability improved

The usefulness of a haptic virtual reality simulator with repetitive training to teach caries removal and periodontal pocket probing skills

Our aim was to evaluate haptic virtual reality (VR) simulation with repetitive training as a tool in teaching caries removal (CR) and periodontal pocket probing (PPP) skills. For the CR simulation, multilayered virtual models composed of tooth substance, caries, and pulp were developed. Seven students completed three training sessions each, which were scored based on the volume of the cut region, the number of instances of handpiece overload, and total cutting time. For the PPP task, we developed a virtual periodontal disease model and 26 students received training in measuring pocket depth. Pocket probing force was measured and proficiency was evaluated. In the CR task, scores for the second and third training sessions were significantly higher than for the first training session. We likewise obtained effective repetitive training results for the PPP task. Our simulator was effective at teaching hand skills for both tasks within short-term evaluation.Yamaguchi S., Yoshida Y., Noborio H., et al. The usefulness of a haptic virtual reality simulator with repetitive training to teach caries removal and periodontal pocket probing skills. Dental Materials Journal 32, 847 (2013); https://doi.org/10.4012/dmj.2013-174

Development of three-dimensional patient face model that enables real-time collision detection and cutting operation for a dental simulator

The virtual reality (VR) simulator is a useful tool to develop dental hand skill. However, VR simulations with reactions of patients have limited computational time to reproduce a face model. Our aim was to develop a patient face model that enables real-time collision detection and cutting operation by using stereolithography (STL) and deterministic finite automaton (DFA) data files. We evaluated dependence of computational cost and constructed the patient face model using the optimum condition for combining STL and DFA data files, and assessed the computational costs for operation in do-nothing, collision, cutting, and combination of collision and cutting. The face model was successfully constructed with low computational costs of 11.3, 18.3, 30.3, and 33.5 ms for do-nothing, collision, cutting, and collision and cutting, respectively. The patient face model could be useful for developing dental hand skill with VR.Yamaguchi S., Yamada Y., Yoshida Y., et al. Development of three-dimensional patient face model that enables real-time collision detection and cutting operation for a dental simulator. Dental Materials Journal 31, 1047 (2012); https://doi.org/10.4012/dmj.2012-164

Development of a multi-layered virtual tooth model for the haptic dental training system

A virtual reality (VR) haptic dental training system could be a promising tool for future dental education. One major challenge is to develop a virtual tooth model which similarly reflected a real tooth having multiple layers with different mechanical hardness in each layer. The multi-layered virtual tooth model was successfully constructed in our virtual system. The constructed model allows us to feel tooth cutting which is similar to that with a real tooth. Through a cutting experiment by using the real tooth, a spring coefficient and a damping coefficient of a dental hard tissue were determined 0.8 N/mm and 1.79 Nsec/mm respectively. The feedback force smoothly altered when crossing the border of regions having different mechanical hardnesses. The constructed model introduced in this study could be a promising tool for acquiring dental hand skills in a virtual learning system.Yoshida Y., Yamaguchi S., Kawamoto Y., et al. Development of a multi-layered virtual tooth model for the haptic dental training system. Dental Materials Journal 30, 1 (2011); https://doi.org/10.4012/dmj.2010-082