A Method for Position Detection of Shaft Motors Using Space Harmonics of Magnetic Flux

Abstract

A new method for detecting position of shaft motors is proposed. A Hall sensor array measures the magnetic flux from the shaft surface. Each Hall sensor output is mixed with given coefficients. The mixed signal provides the fundamental component of the flux distribution of the shaft surface; the space harmonics of the distribution are filtered out. This filtered signal is used to obtain position information with good linearity and precision. A harmonic component can also be extracted by modifying the coefficients. This harmonic signal can be used for position detection with good linearity and precision. In our experiments carried out using the proposed shaft drive system with a span of 360mm, the position error is found to be within ±0.03mm.