Affiliations: [a] Department of Biomedical Engineering, College of Engineering, Peking University, Beijing 100871, China | [b] China Astronaut Research and Training Center, Beijing 100094, China
Correspondence:
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Corresponding author: Tianyu Xie. Department of Biomedical Engineering, College of Engineering, Peking University, Beijing 100871, China. E-mail: tianyu_xie@pku.edu.cn
Abstract: Determining the shape and position of endoscopes has considerable benefits in endoscopic diagnosis and treatment. However, electromagnetic field distortion caused by metal materials, limited field strength and multiple sensors complicate the endoscope localization problem. In this paper, a locally weighted method for the electromagnetic localization of endoscopes that combines the models of the location problem and the errors is proposed. A hardware system, test platform and fixtures are constructed to collect data and evaluate the method. To obtain the global minimum of the objective function, an approach that combines a genetic algorithm with the Levenberg-Marquardt algorithm is developed. Compared to the localization method without weighting, the results show a 5.3:1 improvement in the localization of a naked coil and a 2.4:1 improvement in the localization of a coil inside a piece of endoscope insertion tube. In a transmitter-tracking configuration that limits the field strength and at a much farther distance (closer than 400 mm vs 400--700 mm), this method performs better than previously reported commercial systems in a similar environment. Furthermore, this method can greatly reduce the influence of metal materials used in endoscopes near the transmitter coil. This method can satisfy the demand for endoscope localization.
