Design and Evaluation of an Open-Structure Rotary Magnetic Encoder for Subaqueous Environments

A novel detachable rotary magnetic encoder is proposed, developed, and validated in this study, demonstrating excellent precision and potential for subaqueous applications, regardless of underwater or airborne environments. Utilizing Hall sensors as sensing elements, the encoder generates orthogonal signals relative to incremental disk rotation and incorporates a filter to enhance the signal-to-noise ratio (SNR). Experimental validation confirms the high positioning accuracy and repeatability of the system, with an accurate response to underwater fluctuations of 0.1°. Considering the characteristics of this measurement system, its prospects at underwater robotic arm joints are foreseen, thereby driving the advancement of underwater precision control technology.

I. Introduction

In recent years, the proliferation of underwater exploration and offshore maintenance using robotic arms has underscored the critical need for efficient and accurate position detection devices to correct angular deviations induced by water flow fluctuations. As pivotal position sensors, encoders play an indispensable role in underwater environments. Rotary encoders are commonly employed in the positioning systems of mechanical arms, with optical, capacitive, and magnetic encoders being the most prevalent types [1], [2], [3], [4], [5], [6]. However, due to differences in sensing principles and hardware limitations, optical and capacitive encoders may encounter challenges when dealing with open environments characterized by humidity and high levels of contamination [7].