A Positioning System Design Based on Tunnel Magnetoresistance Sensors for Rapid Zoom Optical Lens
Year: 2025
Type: article
Abstract: In response to the accurate positioning issue for high-speed moving lens groups in rapid zoom optical lenses with voice coil motors (VCMs), we demonstrate a positioning system design based on tunnel magnetoresistance sensors. The equivalent magnetic charge method and finite element method (FEM) simulations were utilized to compute the magnetic field distribution of the magnetic grating encoder. Based on analytical computation, the optimal air gap δS between the sensor and magnetic grating is determined to be δS = 0.15 mm, which balances magnetic flux density amplitude and total harmonic distortion. In addition, a simplified fitting model is proposed to reduce computational complexity. We quantify the magnetic interference of VCM through three-dimensional flux leakage mapping by FEM analysis, deriving an optimal sensor position OS, with a 24 mm y-offset and 20 mm z-offset relative to the VCM’s origin OV. The position error caused by interference remains below 5 μm with maximum deviations at trajectory endpoints of the moving group. The original signal output is processed and corrected, and eventually, the measured displacement exhibits a linear relationship with actual displacement. Our study provides a comprehensive framework for the design and optimization of magnetic positioning systems in optical applications with electromagnetic motors.
Source: Sensors
DOI: 10.3390/s25061820
Authors: Junqiang Gong, Dameng Liu, Jianbin Luo
Institutions: State Key Laboratory of Tribology, Tsinghua University
Language: English
Subfield: Electrical and Electronic Engineering
Field: Engineering
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $3,137
OpenAlex ID: W4408444530