This research is how to implement haptic rendering for a needle insertion problem with volume graphic model. The target is a spine biopsy simulator for tumor inspection by needle insertion. Simulated force is calculated from the relationship of voxel data and the orientation and position of the needle.
The realistic force reflection has been generated by $PHANToM^TM$. The directional force of the needle has been generated by tissue model. The other rotational force is generated using pivot to keep the needle in the initial inserted direction after puncturing skin. Since applied haptic rendering method has used only segmentation data, it is required using voxel density value for more realistic haptic feedback. Moreover, the commercial haptic devices, like PHANToM, have limitations for generating high stiffness and large damping. That also requires developing the device which has a large range of achievable impedance.
MRI T1 value and CT density is used to give physical properties to voxel. Soft tissue can be modeled as a damper using MRI value in the needle insertion problem, and the stiffness of hard tissue is derived from CT density. With this scheme mechanical property of each voxel is determined and the skin deformation is modeled with Kelvin’s viscoelastic model. In order to display high stiffness and large damping for more realistic simulation a hybrid actuator system has been tested which has active actuators and passive devices together. MR brake is used as a passive device, and the effectiveness of the hybrid actuator has been demonstrated. The result shows that the proposed scheme follows the clinical experimental profile with stability.
