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A Flexible, Planar-Coil-Based Sensor for Through-Shaft Angle Sensing
Date Issued
15-12-2018
Author(s)
Abstract
In this paper, a simple angle sensor is presented, which is easy to fabricate and is low cost. The sensor is constructed using square shaped flexible planar coils, bent, and arranged in a cylindrical pattern. The sensor design was verified using appropriate analytical design, and an algorithm to identify the quadrants of the measured angle was developed. The output of the sensor is tolerant toward errors due to the axial displacement of the sensing coil. This makes it suitable for applications where the shaft may be subjected to axial motion (even up to 30% of sensing coil length) in addition to angular motion. The radial space required for the existing through-shaft angle sensors is large. Although capacitive sensors can be employed, their output is sensitive to moisture, dust, and oil. The proposed sensor requires very small radial space (about 1.5mm) and its output is not sensitive to such environmental parameters. A prototype sensor was constructed to verify the sensor operation and to evaluate its performance. The prototype sensor had an rms error of 0.58% and the maximum error was within ±1%. The resolution of the measurement system was estimated to be 0.15°. A detailed error analysis has been conducted and the outcome shows that the output of the sensor has very low sensitivity to the source of errors.
Volume
18