A Novel Wrench–Current Decoupling Strategy to Extend the Use of Small Lookup Data for a Long-Range Maglev Planar Motor

Trakarnchaiyo, Chanuphon; Khamesee, Mir Behrad

doi:10.3390/act12090358

Cited by 1 publication

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References 32 publications

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“…Magnetic levitation finds applications in various fields, such as transportation, aerospace, civil, biomedical, chemical, architectural, and automotive engineering, as detailed in [1]. Within this extensive range of applications, magnetic levitation platforms (MLPs), which are characterized by the absence of mechanical contact between the levitated platform (mover) and the steady base (stator), serve as vibration isolation systems for high-precision manufacturing [2,3], dynamic supporting structures for mirrors in optical pointing and scanning applications [4], zero-power gravity compensation systems [5], e.g., nanometerscale positioning [6], ground-based testing of large optical equipment for space use [7], and cleanroom conveyor systems [8]. Magnetic levitation and precise position measurement are also important when using highly sensitive temperature-compensated quartz sensors that measure position based on capacitive change, as shown in [9,10].…”

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confidence: 99%

Comparative Analysis of Force and Eddy Current Position Sensing Approaches for a Magnetic Levitation Platform with an Exceptional Hovering Distance

Bonetti,

Mirić,

Kolar

2024

Actuators

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This paper provides a comparative analysis between a force sensor and an eddy current sensor, focusing on their usability to determine the position of a circular levitating permanent magnet (PM) mover within an axially symmetric magnetic levitation platform (MLP) with an exceptionally large air gap. The sensors enable closed-loop control, which is essential for accurately and stably maintaining the mover’s radial position. For the considered MLP, a change in radial position in principle results in a tilting of the mover, i.e., a deviation from the parallel alignment relative to the stator. As both the radial position and the tilting angle affect the sensors’ (force and eddy current) output voltage, an observer must deduce the radial position from the output sensor’s voltage, requiring a comprehensive MLP dynamic model and calibration of the models for both sensing approaches. The paper discusses the advantages and weaknesses of each sensor concept, exploring operational principles and performance in levitation tests. The force sensor exhibits versatility, proving functional across various application scenarios, such as when the mover is sealed in a conductive, non-magnetic chamber. In contrast, due to its high-frequency operation, the eddy current sensor is more straightforward to characterize, simplifying its behavior relative to the mover’s slower dynamics. Measurements are conducted to validate the models, showing the eddy current sensor’s robustness against disturbances and imperfections in the MLPs and its immunity to cross-axis interference. Conclusively, in levitation experiments where the mover is vertically distanced at 104 mm from the stator, the eddy current sensor achieves a position tracking precision about ten times better and a signal-to-noise ratio (SNR) ten times higher compared to the off-the-shelf force sensor, confirming its better performance and reliability; however, it cannot be used in applications where conductive objects are present in the air gap. Furthermore, additional experiments are conducted on the MLP using the eddy current sensor to show the controller’s robustness and dynamic reference tracking capability, with and without a payload.

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