OOMOTO Katutoshi Real Vision Research and Development of Graphics Application, 研究部, 主任研究員
KINOSHITA Yoshimasa University of Occupational and Environmental Health Medical Record Information Center, 病院医療情報部, 講師 (00258617)
TANAKA Kazuaki Kyushu Institute Of Technology, Faculty of Computer Science and System Engineering, Lecturer, 情報工学部, 講師 (70253565)
|Budget Amount *help
¥11,600,000 (Direct Cost: ¥11,600,000)
Fiscal Year 2003: ¥3,900,000 (Direct Cost: ¥3,900,000)
Fiscal Year 2002: ¥1,100,000 (Direct Cost: ¥1,100,000)
Fiscal Year 2001: ¥6,600,000 (Direct Cost: ¥6,600,000)
In late years, to reduce medical care mistakes by inexperienced doctors, surgical operation training simulation systems exploiting virtual reality technologies are developed. The most of them support only visual information and do not permit a user to cut dense object models. In this study, by introducing both a voxel model to make a user cut dense object models and a PHANToM as a haptic feedback device to return the sense of touch to the user. When a virtual environment scalps up, it is impossible to make a single PC contend with complicated processes including a haptic rendering, image rendering of Voxel and interference judgment. This problem can be solved by connecting a PC executing a haptic calculation and interference judgment calculation with another PC for voxel rendering using SCRAMNet, which is an optical network permitting shared memory systems.
After detecting interference between voxels constituting a scalpel and a virtual human body voxel model, erase human body voxels wh
en they are cuttable. As the haptic expression in the case when a scalpel interferes with an object, only elastic force and viscosity force are taken into consideration. It is checked if the part of an object interfering with a unit voxel can be cut. If it cannot be cut, the elastic force corresponding to the amount of penetration is returned to a user. When it is cuttable, the following processes are done returning the elastic force corresponding to the amount of penetration to a user. The shearing force based on the amount of movement of the scalpel and the number of voxels interfered with the scalpel is compared with the threshold value of the shearing force of the target model set beforehand. When it is greater than the threshold, making the elastic force invalid and the viscosity resistance is returned based on the velocity of the scalpel. Furthermore, a ' scalpel can go toward the direction of a blade but cannot move toward the perpendicular direction of the blade. To realize such, a constraint, when penetration occurred toward the normal vector from the cuttable plane, the elastic, force feedback corresponding to the amount of the penetration is given to 'the scalpel toward the reverse direction of the normal vector.
In order to evaluate our virtual cutting operation, a model consisting of a skin (soft) model, a meat (elastic) model, a bone (hard) model is cut. Operator tests show the good evaluation of the system developed. However, the haptic feedback device PHANToM used dose not control the rotation of a scalpel because it cannot return any torque. Therefore when a scalpel is suddenly spun coming in an object, unexpected force is rarely returned. It is expected that a model is distorted during cutting operation, but this is not realized yet. We will continue our efforts to solve these problems in near future. Less