A temperature-independent force transducer using one optical fiber with multiple Bragg gratings

Abstract

Typical electrical or piezoelectric force sensors may fail in the industrial applications with strong electromagnetic interference (EMI). To address this issue, this paper develops a new temperature-independent force transducer based on theories of elastic cantilever beam and Bragg wavelength shift in fiber Bragg gratings. The detailed design of the structure and theoretical analysis are given to introduce the measurement principle of the transducer and temperature compensation of fiber Bragg gratings (FBG). Extensive experiments have been conducted to evaluate the performance of the developed force transducer. Experimental results demonstrate that the developed FBG force transducer has a force sensitivity 84.43 pm/kN within a measured range from 0 to 50 kN, which is consistent with the theoretical sensitivity 87.77 pm/kN. Moreover, experimentally the transducer also achieves good linearity, repeatability and temperature independency. The developed force transducer can assist in monitoring the states of heavy-duty machines in the harsh industrial environment.

Theoretical error model of FBG-based surface temperature measurement and its accuracy enhancement

“…1. The traditional temperature sensitivity model of FBG is given by ΔλB=λB(αf+ζ)ΔT, which does not consider the thermal expansion of the fiber coating and the photo-elastic effect of the fiber core (λB is the Bragg wavelength, αf is the thermal expansion coefficient of the fiber core, ζ is the thermal-optic coefficient of the fiber core, and ΔT is the temperature change) [29,30]. To obtain a more accurate sensitivity model, the wavelength variation can be expressed as: (1) where pe=0.224 is the effective photo-elastic coefficient of the fiber core.…”

Actualities and Development of Heavy-Duty CNC Machine Tool Thermal Error Monitoring Technology

“…Refs. [109,110], studied the deformation measurement of heavy-duty CNC machine tool base using fiber Bragg grating array and designed a FBG-based force transducer for the anchor supporting force measurement of the heavy-duty machine tool base. These research can be extended to the analysis of the Figure 27 3-point bending of the RDMS prototype and deformed shape as reconstructed by the measurement system [105] thermal deformation mechanism and thermal deformation measurement of heavy-duty CNC machine tool.…”

Load estimation and vibration monitoring of scale model wind turbine blades through optical fiber sensors

“…Commonly, bare optical strain sensors are directly bound on the surfaces of monitored structures using adhesives to detect strain shifts ( [21,22]), or to measure forces ( [23,24]), or are embedded in some composite material to form smart structures ( [25,26]).…”