Study on Real-Time Tracking of Wireless Capsule Endoscope Based on LM-EM Algorithm

Wireless Capsule Endoscope (WCE) has been widely used in the diagnosis of gastrointestinal diseases due to its non-invasive and convenient characteristics. However, existing localization methods are limited by insufficient accuracy and poor environmental adaptability, making it challenging to meet the requirements in complex digestive tract environments. Therefore, an improved differential localization method based on ring magnets is proposed. This method improves the WCE’s localization performance in geomagnetic environments by combining a differential signal model and a hybrid Levenberg Marquardt - Expectation Maximization (LM-EM) optimization algorithm. Experimental results indicate that, compared to the traditional Levenberg - Marquardt (LM) localization algorithm, the method presented in this paper reduces the position error by 31.9% and the orientation error by 25.7% in static scenarios. In dynamic scenarios, the position and orientation errors are decreased by 67% and 82%, respectively. The established localization platform and the proposed algorithm can provide a reliable solution for the real-time localization of wireless capsule endoscopes in real clinical environments.