Real-Time Positioning of a Magnetically Driven Endoscopic Laser End-Effector Under EMI

This article introduces a novel technique for accurately positioning a toroidal permanent magnet (PM) in a magnetically driven surgical laser ablation end-effector, taking into account the effects of electromagnetic interference (EMI). A novel hybrid optimization algorithm is proposed that designs the initial search direction and step size of the algorithm by analyzing the error function in the iteration. Moreover, the algorithm establishes the boundary value when the hybrid algorithm is initiated, thus facilitating a more effective integration of the global search capabilities of the tree seed algorithm (TSA) and the local search capabilities of the Levenberg-Marquardt (LM) algorithm. Furthermore, precise tracking of the PM in the context of coil-controlled PM motion is accomplished through the use of an accurate coil model and a real-time EMI subtraction algorithm. In the real-time tracking task with an update rate of 25 Hz, the mean absolute error (MAE) and root mean square error (RMSE) of the position error of the hybrid optimization algorithm incorporating the proposed model are 0.0809 and 0.1085 mm, respectively. The MAE and RMSE percentages are 1.84% and 2.17%, respectively. In the laser target tracking experiments, the MAE and RMSE of the tracking error are 0.1339 and 0.1668 mm, respectively, with MAE and RMSE percentages of 2.23% and 2.78%, respectively.