Event-triggered particle swarm optimization-based localization method for underwater fluxgate sensor

The continuous advancement of magnetic shielding technology has posed greater challenges for underwater magnetic target detection. Given that installation position errors are inevitable during the installation of underwater fluxgate sensor, and that significant errors can cause the detection system to fail, a localization method based on event-triggered particle swarm optimization (ET-PSO) is proposed for underwater fluxgate sensors. An energized solenoid coil is used as the magnetic source, and ET-PSO estimates the sensor positions from the recorded magnetic-field measurements. The known range of sensor installation errors is used to guide the initialization of the particle swarm, enabling the algorithm to attain its final global-best solution in fewer iterations. To accommodate inaccurate prior installation information, an event-triggered mechanism dynamically adjusts the search center and radius. Extensive comparative simulations and experiments have demonstrated the effectiveness and superiority of the proposed method. The proposed method achieves satisfactory localization accuracy with a relatively short iteration-stage runtime. In the water-tank experiment, it maintained a mean localization error of 0.0464 m even when the sensor position lay outside the initial search region, demonstrating centimeter-scale localization performance under inaccurate prior information.