Real-Time Attitude Tracking of Capsule Endoscope Based on MEMS IMU and Error Analysis

Wireless capsule endoscope (WCE) has been increasingly exploited for noninvasive screening and diagnosis of the entire esophagus, stomach, colon, and small intestine. WCE allows direct visualization of gastrointestinal tracts and causes less pain to the patients. Automated navigation of WCE during the medical procedure will significantly reduce the testing time and improve the usage and efficiency of medical infrastructure. Attitude tracking of WCE is of great importance for real-time tracking of the position and orientation of capsule endoscope. In this paper, a method for calculating the attitude of WCE based on MEMS IMU (Inertial Measurement Units) is implemented. The accuracy of attitude tracking is measured by a series of experiments. By reorientating the capsule endoscope with a high precision 3D rotary stage, the error from the proposed algorism is determined. The experimental results show that the attitude of WCE based on MEMS IMU can meet the diagnostic requirements in about six minutes, but the performance cannot be maintained due to error accumulation. Additionally, we propose a method to improve the attitude accuracy by reciprocating the rotational motion during the inspection process.