Paper Info
Title
Performance Analysis of a Lower Limb Multi Joint Angle Sensor Using CYTOP Fiber: Influence of Light Source Wavelength and Angular Velocity Compensation.
Abstract
This paper presents the analysis of an intensity variation polymer optical fiber (POF)-based angle sensor performance, i.e., sensitivity, hysteresis and determination coefficient (R2), using cyclic transparent optical polymer (CYTOP) fiber. The analysis consisted of two approaches: influence of different light source central wavelengths (430 nm, 530 nm, 660 nm, 870 nm and 950 nm) and influence of different angular velocities (0.70 rad/s,0.87 rad/s,1.16 rad/s,1.75 rad/s and3.49 rad/s). The first approach aimed to select the source which resulted in the most suitable performance regarding highest sensitivity and linearity while maintaining lowest hysteresis, through the figure of merit. Thereafter, the analysis of different angular velocities was performed to evaluate the influence of velocity in the curvature sensor performance. Then, a discrete angular velocity compensation was proposed in order to reduce the root-mean-square error (RMSE) of responses for different angular velocities. Ten tests for each analysis were performed with angular range of0 degrees to50 degrees, based on knee and ankle angle range during the gait. The curvature sensor was applied in patterns simulating the knee and ankle during the gait. Results show repeatability and the best sensor performance for lambda=950 nm in the first analysis and show high errors for high angular velocities (w=3.49 rad/s) in the second analysis, which presented up to50% angular error. The uncompensated RMSE was high for all velocities (6.45 degrees to12.41 degrees), whereas the compensated RMSE decreased up to74% (1.67 degrees to3.62 degrees). The compensated responses of application tests showed maximum error of5.52 degrees and minimum of1.06 degrees, presenting a decrease of mean angular error up to30 degrees when compared with uncompensated responses.
Year
DOI
Venue
2020
10.3390/s20020326
SENSORS
Keywords
Field
DocType
movement analysis,optical fiber sensors,joint angle,cytop
Optical fiber,Analytical chemistry,Angular velocity,Curvature,Linearity,Optics,Hysteresis,Figure of merit,Engineering,Wavelength,Repeatability
Journal
Volume
Issue
ISSN
20
2.0
1424-8220
Citations 
PageRank 
References 
0
0.34
0
Authors
4
Name
Order
Citations
PageRank
Letícia Avellar100.34
Arnaldo Leal-Junior200.34
Carlos A. F. Marques32312.72
Anselmo Frizera42510.89