As the anatomic structures, for example bone thickness, are different and the destruction of the membrane lining the inner ear can lead to a damage of organ functions, for example deafness or vertigo, the protection of soft tissue structures behind the ablated bone in skull base surgery is mandatory. Consequently, a safer and more accurate Cochlear Implantation technology need to be developed urgently. For the detection of the boundary between soft tissue and bone the laser bone ablation system which was based on the combination of laser, robotics, coaxial monitoring and vision navigation was developed for a micro surgery at the skull base. Through this the laser is guided across the ablation area by vision navigation technologies. In this paper our laser bone ablation system and the first results of the boundary detection are described.

On account of its sensitivity to external interferences of the magnetic field, the electric compass itself is not accurate enough to be used for localization compared with the rate gyroscope. To overcome this shortcoming, in this research, a robust electric compass was designed by using two electric compasses to efficiently cancel out the low-frequency interferences. That is, in this paper, a double electric compass predictive calibration algorithm which corrects irregular and long-lasting magnetic-field interferences is newly proposed and implemented. When the external interferences are eliminated from the double electric compass, it becomes much more accurate than the gyroscope-based system that suffers from accumulative drift error. The reliability and performance of the designed system were verified through real navigation experiments