Abstract:In endoscopic examination, the subjective judgment error is involved by doctors’ limited experience. The EMT (Electro-magnetic Tracing) technology could be effective in scientifically tracking the micro probe by implanting mini magnetic sensors. However, the precision could be badly declined when magnetic interference occurs. In this article, an improved attitude algorithm is proposed by introducing multi-sensor convergence technology. To lower the magnetic disturbance, the system combines inertial sensor unit to make use of gyroscope and quaternion differential equation as fundamental attitude estimation, with two-vector FQA (Factored Quaternion Algorithm) method converging the random drift error caused by MEMS gyroscope. We also fuse a threshold criterion in case of the hard-over magnetic distortion. The preliminary experiment shows that multisensory system possesses good accuracy with angular drift less than 1°and could maintain high anti-interference stability.