The electromagnetic tracking system is widely used in clinical applications, e.g. image-guided interventions. However, the slow measurement speed, low tracker accuracy due to nearby metallic objects prevent electromagnetic tracking system from being more widely used in clinics. This project aims to improve the clinical electromagnetic tracking system with the following features: Fast tracking speed and robustness to ambient metals and electronic devices. The research result will provide the solutions in software. In clinical setup, no additional hardware are needed. Therefore, the established clinical workflows do not need to be changed.