In a study published in IEEE/ASME TRANSACTIONS ON MECHATRONICS, the research group led by Prof. DAI Houde from Fujian Institute of Research on the Structure of Matter (FJIRSM) of the Chinese Academy of Sciences reported a simplified MPA to calculate an AGV’s 2-D position based on the analytical method of a single tri-axis magnetometer and data fusion strategy based on confidence criterion between positioning results of multiple tri-axis magnetometers. 

The researchers first buried an axially magnetized cylindrical NdFeB magnet in the ground as a magnetic nail (MN) with the direction from the south pole to the north pole of the MN being perpendicular to the ground. The analytical expression for calculating the 2-D position of an MN was derived from the magnetic dipole model and the sensed magnetic field intensities from a single tri-axis magnetometer.  

The researchers then fused the positioning results of multiple magnetometers based on the confidence criterion. The experimental results showed that a single magnetometer can succeed in determining the 2-D position of an MN, and that the multisensor fusion result could improve the positioning accuracy and robustness, where the average position error was reduced from 1.67±0.70 mm to 0.72±0.54 mm. 

Besides, the researchers revealed that the new MPA doesn’t need an initial guess value and can run on the MCU in real-time with an average positioning time of 29.00±4.88 ms on the STM32 MCU. The average positioning time of the previous used MPA is 241.25±79.50 ms. 

This study provides a new concept of high-precision MPA for AGV applications without complicated visual perception.