Revolutionizing Precision Weighing: Integrating Magnetic Levitation with OAV Air Bearings


Precision mass measurement stands as a cornerstone across a spectrum of industries, driving standardized products and meticulous defect inspection. Traditionally, two pieces of technology have dominated this arena: strain gauge load cells and electromagnetic force compensation (EMFC) weighing cells. Yet, both have faltered in the face of evolving demands, hampered by issues of accuracy, speed, and ruggedness.

Strain gauge load cells, while strong and cost-effective, have grappled with limited accuracy and sluggish weighing speeds due to inherent damping deficiencies and resonant behaviors. Conversely, EMFC weighing cells, celebrated for their high repeatability and resolution, have been obstructed by tardy settling times and vulnerability to impact or overweight, courtesy of their flexure-based mechanisms.

In an effort to overcome these challenges, a recent scholarly endeavor unveiled a groundbreaking innovation: an EMFC weighing cell with magnetic levitation and OAV Air Bearing technologies. This paradigm-shifting solution was engineered to deliver swift settling times and unmatched ruggedness. Unlike its conventional counterparts reliant on flexure mechanisms, the proposed weighing cell leverages magnetic levitation harnessed through carefully crafted magnetic springs providing near-zero and negative stiffness. Complementing this innovation, OAV Air Bushings were at the center stage, bolstering load capacity, enhancing ruggedness, and mitigating measurement errors stemming from external forces.

                                Figure 1: EMFC weighing cell with depicted mechanisms and configurations

Key Features of the Proposed Solution:

  1. Magnetic Springs: These masterfully engineered components effortlessly offset deadweight while providing the system with near-zero stiffness, thus ushering in rapid settling times and heightened sensitivity.

  2. OAV Air Bushings: The OAV Air Bushings replaced traditional flexure mechanisms, increasing load capacity and fortifying ruggedness while minimizing measurement errors.

  3. High-precision Sensors and Actuators: The system integrated cutting-edge optical encoders for precise position sensing and voice coil motors (VCMs) for exacting force generation.

                                              Figure 2: Experimental setup for weight measurment

The design and optimization journey of the magnetic springs were marked by intricate considerations spanning static force requisites, size parameters, and stiffness minimization. Through combination of advanced optimization techniques and analytical modeling, the final design was highly successful, embodying the desired attributes of near-zero stiffness and gravity compensation, all within the stipulated constraints.

The optimized EMFC weighing cell, heralding a new era in precision weighing, showcased remarkable strides in settling time, ruggedness, and accuracy, outclassing its conventional counterparts. By harnessing the synergistic prowess of magnetic levitation and OAV Air Bushings, this pioneering solution opened up ways for unparalleled precision in diverse industries, especially those operating within dynamic weighing environments.

The convergence of magnetic levitation and OAV technologies signaled a seismic shift in high-precision weighing technology, effectively preventing former limitations and paving the way for enhanced productivity and quality across various industries. The fusion of magnetic levitation and OAV Air Bushings not only represents a huge leap in weighing technology, but also underscores a transformative approach to precision mass measurement. With precision redefined and limitations transcended, the future shows unprecedented levels of accuracy and efficiency in high-speed, high-accuracy weighing applications, underlining the pivotal role of OAV in this transformative journey.

Kyung-Taek Yoon et al 2021 Meas. Sci. Technol. 32 015905

This material is based on work supported by the Department of Mechanical Engineering of Ajou University.


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