Development of Open-structure Rotary Magnetic Encoder for Underwater Applications

This paper presents development of an open-structure rotary magnetic encoder and validation of signal integrity without additional waterproof protection, demonstrating excellent performance for potential underwater applications. The encoder utilizes two sets of Hall sensors to generate orthogonal signals and incorporates nonlinear curve fitting to adjust the measured data under various flying height, which can be used to adapt to interferences from surrounding media. Through experimental validation, it is found that the proposed system offers positioning accuracy and repeatability in water comparable to and even better than those achieved in air, while enhancing the signal-to-noise ratio and enabling accurate detection of small angular fluctuations. Furthermore, the compact size of this rotary magnetic encoder makes it suitable for installation in mechanical arm joints to compensate for minor angular deviations that may result in misalignment of the end-point's target position.