Avoidance Method of Magnetic Target Positioning-Inaccuracy-Area.

Magnetic positioning technology is safe, practical, and cost-effective, and is getting increasingly emphasized in many fields such as biomedicine and geophysics. However, magnetic positioning methods have a positioning-inaccuracy-area (positioning error is significantly greater than that in the adjacent area). This paper establishes an Omni-posture error model to explore the variation law of the positioning error and finds that the included angle φ between the magnetic moment vector and the position vector determines the distribution of the positioning error. Using wireless communication to send commands and adjusting the current vector to change φ, we propose an avoidance method of positioning-inaccuracy-area (AMP). Simulation results show that when using the AMP to track a wireless capsule endoscope (WCE) with an arbitrary posture, the positioning error is 5.5 mm and the orientation error is 1.64°. The experimental results in a magnetically shielded room show that the positioning error of the AMP is 12 mm, which reduces the positioning error before avoidance by 95.5%. The simulation and experimental results both prove that the AMP can effectively avoid the positioning-inaccuracy-area of the magnetic positioning method, thereby improving the positioning accuracy.