3-D Positioning Method of Pipeline Robots Based on a Rotating Permanent Magnet Mechanical Antenna

At present, the 3-D positioning of pipeline robots is limited by complex structures, large device sizes, and difficulties in the miniaturization of the sensor array. In this article, a multipoint magnetic field measurement method (MFM) is proposed for the spatial positioning of pipeline robots. The method can effectively obtain the 3-D coordinate positioning of pipeline robots in a short range, without complex sensor arrays, and without knowing the direction of the pipeline in advance. Furthermore, to address the problem in which weak magnetic field value is very susceptible to background noise and ferromagnetic interference in the environment, a dislocation superposition method (DSM) is developed to process the measured signals. In the MFM, a rotating permanent magnet mechanical antenna is used as the transmitter of low-frequency magnetic signals due to its advantages of small size, low energy consumption, and high radiation efficiency. Moreover, a single three-axis fluxgate sensor is used to measure the magnetic signal at multiple points. Finally, to verify the superiority of the proposed MFM and DSM, experiments are carried out in a seabed engineering laboratory. The test results show that the average absolute error of ${x}$ -axis positioning is 0.04 m, the average absolute error of ${y}$ -axis positioning is 0.01 m, and the average absolute error of ${z}$ -axis positioning is 0.07 m.