A spin tracing algorithm applied to mini-type magnetic bearing meter and its SoC implementation

Due to its large mechanical structure, the standard magnetic-flux-gate bearing-based meter cannot be housed in the very small space available on some small mobile machines. Although the semiconductor magnetic-effect-based bearing meter has miniaturizing potential, its longterm temperature stability and its azimuth measurement accuracy are not as good as those of the magnetic-flux-gate bearing meter. To solve the problem of miniaturizing the dimension of the magnetic-flux-gate-based bearing meter, this paper presents a spin-tracing algorithm (STA) developed to study a mini-type magnetic bearing meter. First, an orthogonal projection vector is structured by analyzing the magnetic bearing sensor´s working principle. A theoretic expression is derived which can be used to control the tracing computation process of getting azimuth data by exploiting the triangle transform. The structure and the stability of the STA algorithm are also discussed in the paper. Furthermore, a relation between the tracing step length Δβ and the maximum computation step number N_max at any sample is set up. The STA algorithm has been implemented as a system-on-chip based on an FPGA. Finally, the experimental data from the mini-type magnetic bearing meter based on the STA algorithm as well as its specifications are given. The experimental results show that the STA algorithm is not only efficient in miniaturizing the size of the meter, but also is excellent in improving upon the system accuracy which is two times higher than that of the old meter.